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Background. The literature data on the synthesis and properties of mixed-metal complexes of 3d metals with ammonium vanadate and 5-amino-2-mercaptobenzimidazole is limited. Thus, the synthesis and study heterometallic compounds allowed elaborating new aspects of coordination chemistry. Purpose. Elaboration of the synthesis method for mixed-metal complexes of Mn (II), Co (II), Ni (II), Cu (II) and Zn nitrates with ammonium vanadate and 5-amino-2-mercaptobenzimidazole (L) and study of their composition and structure with modern physical and chemical methods. Methodology. A technique for synthesis of mixed-metal complex compounds has been elaborated. For their synthesis, an alcoholic solution of the ligand (molar ratio M: M: L=1: 2: 2) was added to solution of ammonium vanadate and metal chlorides, pH 8. The reaction had been carried out at heating for 40 min. The coordinating competitive donor centers, the electronic and geometric structure of the ligand molecule were investigated by quantum-chemical calculations using the DFT / V3LIP / LanL2DZ method in the Gaussian09 software package. The composition and structure of the synthesized mixed-metal complex compounds were investigated by the methods of elemental, thermal analysis and FTIR- spectroscopy. Originality. A procedure has been developed for synthesis of mixed-metal complex compounds: Mn (II), Co (II), Ni (II), Cu (II), Zn nitrates with ammonium vanadate and 5-amino-2-mercaptobenzimidazole. It was found that in complexation reactions the ligand molecule is coordinated through the nitrogen atom with the negative value of the effective partially localized charge. Findings. The data on coordinating competitive donor centers, the electronic and geometric structure of the ligand molecule. [ABSTRACT FROM AUTHOR]

The [Co(Pyridine)(CO2)]- anionic complex was studied through the combination of photoelectron spectroscopy and density functional theory calculations. This complex was envisioned as a primitive model system for studying CO2 binding to negatively charged sites in metal organic frameworks. The vertical detachment energy (VDE) measured via the photoelectron spectrum is 2.7 eV. Our calculations imply a structure for [Co(Pyridine)(CO2)]- in which a central cobalt atom is bound to pyridine and CO2 moieties on either sides. This structure was validated by acceptable agreement between the calculated and measured VDE values. Based on our calculations, we found CO2 to be bound within the anionic complex by 1.4 eV. [ABSTRACT FROM AUTHOR]

Based on extensive ab initio calculations and the time-propagation of the nuclear Schrödinger equation, we study the vibrational relaxation dynamics and resulting spectral signatures of the OH stretch vibration of a hydrogen-bonded complex, HCO2- · H2O. Despite their smallness, it has been shown experimentally by Johnson and coworkers that the gas-phase infrared spectra of these types of complexes exhibit much of the complexity commonly observed for hydrogen-bonded systems. That is, the OH stretch band exhibits a significant red shift together with an extreme broadening and a pronounced substructure, which reflects its very strong anharmonicity. Employing an adiabatic separation of time scales between the three intramolecular high-frequency modes of the water molecule and the three most important intermolecular low-frequency modes of the complex, we calculate potential energy surfaces (PESs) of the ground and the first excited states of the high-frequency modes and identify a vibrational conical intersection between the PESs of the OH stretch fundamental and the HOH bend overtone. By performing a time-dependent propagation of the resulting system, we show that the conical intersection affects a coherent population transfer between the two states, the first step of which being ultrafast (60 fs) and irreversible. The subsequent relaxation of vibrational energy into the HOH bend and ground state occurs incoherently but also quite fast (1 ps), although the corresponding PESs are well separated in energy. Owing to the smaller effective mass difference between light and heavy degrees of freedom, the adiabatic ansatz is consequently less significant for vibrations than in the electronic case. Based on the model, we consider several approximations to calculate the measured Ar-tag action spectrum of HCO2- · H2O and achieve semiquantitative agreement with the experiment. [ABSTRACT FROM AUTHOR]

Transition metal-fullerenes complexes with metal atoms bound on the external surface of C60 are promising building blocks for next-generation fuel cells and catalysts. Yet, at variance with endohedralM@C60, they have received a limited attention. By resorting to first principles simulations, we elucidate structural and electronic properties for the Pd-C60, Pt-C60, PtPd-C60, Pd2-C60, and Pt2-C60 complexes. The most stable structures feature the metal atom located above a high electron density site, namely, the π bond between two adjacent hexagons (π-66 bond). When two metal atoms are added, the most stable configuration is those in which metal atoms still stand on π-66 bonds but tends to clusterize. The electronic structure, rationalized in terms of localized Wannier functions, provides a clear picture of the underlying interactions responsible for the stability or instability of the complexes, showing a strict relationship between structure and electronic gap. [ABSTRACT FROM AUTHOR]

Electron attachment to uracil was investigated by applying time-resolved photoelectron imaging to iodide-uracil (I-U) complexes. In these studies, an ultraviolet pump pulse initiated charge transfer from the iodide to the uracil, and the resulting dynamics of the uracil temporary negative ion were probed. Five different excitation energies were used, 4.00 eV, 4.07 eV, 4.14 eV, 4.21 eV, and 4.66 eV. At the four lowest excitation energies, which lie near the vertical detachment energy of the I-U complex (4.11 eV), signatures of both the dipole bound (DB) as well as the valence bound (VB) anion of uracil were observed. In contrast, only the VB anion was observed at 4.66 eV, in agreement with previous experiments in this higher energy range. The early-time dynamics of both states were highly excitation energy dependent. The rise time of the DB anion signal was ~250 fs at 4.00 eV and 4.07 eV, ~120 fs at 4.14 eV and cross-correlation limited at 4.21 eV. The VB anion rise time also changed with excitation energy, ranging from 200 to 300 fs for excitation energies 4.00-4.21 eV, to a cross-correlation limited time at 4.66 eV. The results suggest that the DB state acts as a "doorway" state to the VB anion at 4.00-4.21 eV, while direct attachment to the VB anion occurs at 4.66 eV. [ABSTRACT FROM AUTHOR]

A new, four-dimensional potential energy surface for the interaction of NH3 and ND3 with Ar is computed using the coupled-cluster method with single, double, and perturbative triple excitations and large basis sets. The umbrella motion of the ammonia molecule is explicitly taken into account. The bound states of both NH3-Ar and ND3-Ar are calculated on this potential for total angular momentum values from J = 0 to 10, with the inclusion of Coriolis interactions. The energies and splittings of the rovibrational levels are in excellent agreement with the extensive high-resolution spectroscopic data accumulated over the years in the infrared and microwave regions for both complexes, which demonstrates the quality of the potential energy surface. [ABSTRACT FROM AUTHOR]

Hydrated Fe+ ions are produced in a laser-vaporization cluster source of a triple quadrupole mass spectrometer. The Fe+(H2O)n (n = 3-8) complexes are mass-selected and probed with infrared (IR) photodissociation spectroscopy in the OH-stretch region. Density functional theory (DFT) calculations are also carried out for analyzing the experimental IR spectra and for evaluating thermodynamic quantities of low-lying isomers. Solvation through H-bonding instead of direct coordination to Fe+ is observed already at n = 3, indicating the completion of the first hydration shell with two H2O molecules. Size dependent variations in the spectra for n = 5-7 provide evidence for the second-shell completion at n = 6, where a linearly coordinated Fe+(H2O)2 subunit is solvated with four H2O molecules. Overall spectral features for n = 3-8 agree well with those predicted for 2-coordinated structures. DFT calculations predict that such 2-coordinated structures are lowest in energy for smaller n. However, 4-coordinated isomers are predicted to be more stable for n = 7 and 8; the energy ordering is in conflict with the IR spectroscopic observation. Examination of free energy as a function of temperature suggests that the ordering of the isomers at warmer temperatures can be different from the ordering near 0 K. For n = 7 and 8, the 4-coordinated isomers should be observed at low temperatures because they are lowest in enthalpy. Meanwhile, outer-shell waters in the 2-coordinated structures are bound less rigidly; their contribution to entropy is rather large. The 2-coordinated structures become abundant at warmer temperatures, owing to the entropy effect. [ABSTRACT FROM AUTHOR]

C2H4...Ag-Cl has been synthesised in the gas phase in a pulsed-jet, Fourier-transform microwave spectrometer by the reaction of laser-ablated metallic silver with carbon tetrachloride to give AgCl, which subsequently reacts with ethene to give the complex. The ground-state rotational spectra of six isotopologues (C2H4...107Ag35Cl, C2H4...109Ag35Cl, C2H4...107Ag37Cl, C2H4...109Ag37Cl, 13C2H4...107Ag35Cl, and 13C2H4...109Ag35Cl) were recorded and analysed to give rotational constants A0, B0, and C0, centrifugal distortion constants ΔJ and ΔJK, and Cl nuclear quadrupole coupling constants χaa(Cl) and χbb(Cl) - χcc(Cl). These spectroscopic constants were interpreted in terms of a geometry for C2H4...Ag-Cl of C2V symmetry in which the AgCl molecule lies along the C2 axis of ethene that is perpendicular to the C2H4 plane. The Ag atom forms a bond to the midpoint (*) of the ethene π bond. A partial rs-geometry and a r0-geometry were determined, with the values r(*...Ag) = 2.1719(9) Å, r(C-C) = 1.3518(4) Å, and r(Ag-Cl) = 2.2724(8) Å obtained in the latter case. The C-C bond lengthens on formation of the complex. Detailed ab initio calculations carried out at the CCSD(T)/cc-pVQZ level of theory give results in good agreement with experiment and also reveal that the ethene molecule undergoes a small angular distortion. The distortion is such that the four H atoms move in a direction away from Ag but remain coplanar. The two C atoms are no longer contained in this plane, however. The electric charge redistribution when C2H4...Ag-Cl is formed and the strength of the π...Ag bond are discussed. [ABSTRACT FROM AUTHOR]

We investigate the quantum dynamics of energy and charge transfer in a wheel-shaped artificial photosynthetic antenna-reaction center complex. This complex consists of six light-harvesting chromophores and an electron-acceptor fullerene. To describe quantum effects on a femtosecond time scale, we derive the set of exact non-Markovian equations for the Heisenberg operators of this photosynthetic complex in contact with a Gaussian heat bath. With these equations we can analyze the regime of strong system-bath interactions, where reorganization energies are of the order of the intersite exciton couplings. We show that the energy of the initially excited antenna chromophores is efficiently funneled to the porphyrin-fullerene reaction center, where a charge-separated state is set up in a few picoseconds, with a quantum yield of the order of 95%. In the single-exciton regime, with one antenna chromophore being initially excited, we observe quantum beatings of energy between two resonant antenna chromophores with a decoherence time of ∼100 fs. We also analyze the double-exciton regime, when two porphyrin molecules involved in the reaction center are initially excited. In this regime we obtain pronounced quantum oscillations of the charge on the fullerene molecule with a decoherence time of about 20 fs (at liquid nitrogen temperatures). These results show a way to directly detect quantum effects in artificial photosynthetic systems. [ABSTRACT FROM AUTHOR]

Electron attachment to clusters of N2O in the energy range of 0-4 eV yields the ionic complexes [(N2O)nO]-, [(N2O)nNO]-, and (N2O)n- . The shape of the ion yields of the three homologous series differs substantially reflecting the different formation mechanisms. While the generation of [(N2O)nO]- can be assigned to dissociative electron attachment (DEA) of an individual N2O molecule in the target cluster, the formation of [(N2O)nNO]- is interpreted via a sequence of ion molecule reactions involving the formation of O- via DEA in the first step. The nondecomposed complexes (N2O)n- are preferentially formed at very low energies (below 0.5 eV) as a result of intramolecular stabilization of a diffuse molecular anion at low energy. The ion yields of [(N2O)nO]- and (N2O)n- versus electron energy show sharp peaks at the threshold region, which can be assigned to vibrational Feshbach resonances mediated by the diffuse anion state as already observed in an ultrahigh resolution electron attachment study of N2O clusters [E. Leber, S. Barsotti, J. Bömmels, J. M. Weber, I. I. Fabrikant, M.-W. Ruf, and H. Hotop, Chem. Phys. Lett. 325, 345 (2000)]. [ABSTRACT FROM AUTHOR]

Benzothiazole derivatives are highly selective and an antitumor therapeutic in vitro and in vivo, highlighting the compound 2‐ (4′‐aminophenyl) benzothiazole (ABT), which exhibits nanomolar concentration activity in vitro against some human breast cancer cells in humans. In this work, we designed new contrast agents based on the structural modification of ABT by complexing them with manganese in order to obtain paramagnetic complexes for efficient diagnosis of breast cancer. The new agents were evaluated by docking studies that allowed investigating interactions and the mode of connection between the active site of the enzyme and the compounds studied. The theoretical and experimental results both indicate that Compound 57 is a promising contrast agent. The novel 2‐ (4′‐aminophenyl) benzothiazole derivatives (ABT) were evaluated by docking studies, the compound 57 was selected as the most active compound and thus synthesized and characterized by 1 HNMR, 13 CNMR and MS. Tests were performed to evaluate cell viability, demonstrating that said compound have antiproliferative activity on the MCF‐7 lineage. Thus, compound may be useful both in the diagnosis and in the antitumor agent. [ABSTRACT FROM AUTHOR]

Abstract A Pd(II) complex of tetradentate Schiff base ligand, bis(5-methoxysalicylidene)-4-methyl benzene-1,2-diamine (H 2 L) was prepared from Pd(OAc) 2 in refluxing acetonitrile. The complex was characterized using FT-IR, lH NMR, 13C{1H} NMR spectroscopic techniques, elemental analyses (CHN). Also, its molecular structure was determined by single-crystal X-ray diffraction. The crystal structure data showed a tetradentate mode of coordination for Schiff base, through N 2 O 2 donor sets. In addition, DFT calculations at M06-2X/Def2-TZVP level of theory were conducted to obtain electronic and structural properties of the studied species. NBO-CMO analysis combined with TD-DFT method was done to interpret electronic transitions by determining their included occupied and virtual orbitals. NBO-CMO data show that there are MMCT and LMCT in the studied complex. All theoretical data are in line with the experimental results. Highlights • Synthesis, characterization and spectral properties of new Pd(II) Schiff base complex. • Geometry distorted square-planar around Pd(II). • Structural and DFT studies of the new Pd(II) complex. [ABSTRACT FROM AUTHOR]

Abstract A series of vital complexes of [Se (Ln) (Cl) x ]· y Cl (where n = L1, L2, L3 and L4; x = 1, 2, or 3 and y = 1, 2, or 3) and [Ru (Ln) (Cl) x (H 2 O) y ] z Cl (where x = 2 or 3; y = 0,1 or 2 and z = 0 or 1) have been synthesized from the chemical reactions between ruthenium (III) or selenium (IV) salts and tri-substituted s-triazine derivatives (L 1 = N2-(4-chlorophenyl)-N4,N6-di (pyrimidin-2-yl)-1,3,5-triazine-2,4,6-triamine; L 2 = N2-(4-chlorophenyl)-N4- (pyrimidin-2-yl)- N6- (thiazol-2-yl)-1,3,5-triazine-2,4,6-triamine; L 3 = 6-chloro-N2-(pyrimidin-2-yl)-N4-(1H-1,2,4-triazol-3-yl)-1,3,5-triazine-2,4-diamine and L 4 = 6-chloro-N2-(4-chlorophenyl)-N4-(pyrimidin-2-yl)-1,3,5-triazine-2,4-diamine). The structural was investigated using of elemental analyses, molar conductance, IR, UV–Vis, magnetic susceptibility, 1H, 13C NMR spectra and thermal analyses. The surface morphology behaviors of selenium (IV) and ruthenium (III) complexes were studied based on scanning and transmittance electron microscopes. The crystalline nature of s-triazine complexes have been investigated using X-ray powder diffraction spectra. Spectral results were concluded that the ligand acts as a neutral bidentate for (L 1 and L 4 ) and tridentate for (L 2 and L 3 ), and coordinates through the nitrogen atom of triazine ring and nitrogen atoms of (pyrimidine, thiazole, and triazole) rings towards metal ion. The cytotoxic IC 50 results of the free L n ligands and its selenium (IV) complexes in vitro against the human colon and lung cancer cell lines introduced a promising efficiency. Graphical abstract Structures of new Ru(III) and Se(IV) triazine complexes. Image 1 Highlights • Triazine complexes of Se(IV) and Ru(III) ions have been synthesized. • Structural, spectroscopic and thermal analyses were discussed. • The crystalline nature of s-triazine complexes have investigated. • Se(IV) and Ru(III) complexes display square and octahedral geometries. • Cytotoxic test were scanned in vitro against colon and lung cancer cell lines. [ABSTRACT FROM AUTHOR]

Abstract A new Schiff base, HL , derived from condensation reaction of 2,4-dihydroxybenzaldehyde and 4-amino-3-methyl-1 H -1,2,4-triazole-5(4 H)-thione together with its Ni(II) complex have been synthesized and characterized by several spectroscopies methods. The optimized geometries, assignment of the IR bands and NMR chemical shifts as well as exploring of the frontier orbitals of two synthesized compounds have been calculated using the density functional theory (DFT) procedures. The most stable tautomer of the HL Schiff base and kinetics of its tautomerization have been explored theoretically. In the square planar structure of the [Ni(L)Cl] complex, the anionic L - acts as a NOS tridentate ligand. The chloro ligand is positioned trans to the azomethine nitrogen. The DFT-computed IR frequencies and NMR chemical shifts are good in agreement with their corresponding experimental values, approving validity of the optimized geometries for two investigated compounds. The [Ni(L)Cl] complex exhibits high catalytic activities in a three-component cyclocondensation for synthesis of the tetrahydrobenzo [ b ]pyrans. Graphical abstract Image 1 Highlights • A new 1,2,4-triazole Schiff base and its Ni(II) complex have been newly synthesized. • Optimized geometries and assignments of the IR and NMR spectra have been computed using the DFT methods. • The synthesized Schiff base (HL) acts as a NOS tridentate ligand. • The chloro ligand occupies the 4th coordination position of the square [Ni(L)Cl] complex. • Catalytic behavior of the [Ni(L)Cl] complex has been investigated. [ABSTRACT FROM AUTHOR]

Abstract A new dibenzimidazole compound (1) and three dibenzimidazolium salts (2a-2c) were prepared. Reactions of these salts with silver(I) oxide in methanol led to dinuclear N-heterocyclic carbene silver complexes (3a-3c). All of the compounds were characterized by 1H NMR, 13C NMR and elemental analyses. Molecular weights of the silver complexes were confirmed by MALDI-TOF mass spectrometry. Preliminary catalytic studies using all the silver complexes were performed on three-component coupling reaction of p -formaldehyde, piperidine and phenylacetylene. Complexes 3a and 3c exhibited good catalytic activities under neat conditions. The silver complexes showed luminescence properties in CH 3 CN at room temperature. Graphical abstract Image 1 Highlights • New N-heterocyclic carbene precursors and their dinuclear silver complexes were synthesized and characterized. • Silver complexes were tested as catalysts in the coupling reaction of piperidine, p-formaldehyde and phenylacetylene. • Silver complexes were observed to be luminescent. [ABSTRACT FROM AUTHOR]

Abstract A Schiff base ligand HL has been synthesized by the condensation of an equimolar amount of 2-hydroxy-4-methoxybenzaldehyde and 3-amino-1,2,4-triazole and characterized by elemental analysis, IR, 1H NMR, 13C NMR and ESI-mass spectrometry. The metal complexes 1–4 have been synthesized by the reaction of ligand with Co(II), Ni(II), Cu(II) and Zn(II) chlorides in ethanol in the molar ratio 1:1. All the metal complexes 1–4 were characterized by elemental analysis, molar conductance, electronic spectra, IR, and EPR spectra. TGA has been done to check the stability of the synthesized Schiff base ligand HL and its metal complexes 1–4. Spectral data reveals that the ligand HL acts as uninegative tridentate for metal complexes. The geometries of synthesized ligand and its metal complexes were optimized by using Gaussian 09 W program. On the basis of spectral characterization, octahedral geometry has been allocated for Co(II), tetrahedral for Ni(II), tetragonal for Cu(II) and tetrahedral for Zn(II) complexes. The DNA binding studies of metal complex have been investigated by UV absorbance, fluorescence and CD spectrometry. UV absorbance binding studies show that metal complex 1–3 could bind to ctDNA significantly and the results obtained were consistent with the fluorescence and CD spectra. Graphical abstract HOMO and LUMO of Schiff base ligand HL. Image 1 Highlights • Synthesis of 1,2,4-triazole derived Schiff base ligand and its metal complexes. • Characterization by IR, 1H NMR, 13C NMR, ESI-mass, EPR, electronic spectra and TGA. • Ligand HL acts as uninegative tridentate fashion. • Complexes possessed octahedral, tetrahedral, tetragonal, and tetrahedral geometry. • DNA binding of the metal complexes by UV absorbance, fluorescence and CD spectrometry. [ABSTRACT FROM AUTHOR]

Abstract Two new three-dimensional coordination polymers (CPs), [Co(H 2 L2−) (bibp)]·2H 2 O (1) and [Co 2 (L4−) (bib) 2 ]·8H 2 O (2) (bib = 1,4-diimidazolyl butane, bibp = 4,4′-diimidazolylbiphenyl) have been solvo-/hydrothermal prepared based on tetradentate ligand 5,5-(pentane-1,4-diylbis (oxy))diisophthalic acid (H 4 L). In CP 1 , two chains was formed by Co(II) ion with ligands H 2 L2− and bibp, respectively, then two chains form into a 2D layer through Co(II) ion. The same two 2D layers constitute a AB layer by inverted manner, then a 3D framework was obtained through the combination of AB layer by π-π stacking. In CP 2 , Co (II) atoms are connected by neighboring carboxylic acid ligands L4− to generate 2D layer, then being further connected with nitrogen-containing ligand bib, the 2D layer form a 3D supramolecular network through Co(II) ions. In addition, the electrochemical behaviors of complexes 1 and 2 have been reported. Graphical abstract Image 1 Highlights • The 5,5-(pentane-1,4-diylbis(oxy)) diisophthalic acid is a good building block. • The electrochemical behavior of Co(II) complexes was studied by cyclic voltammetry. • Coordination polymer 1 showed a 2D layer, and coordination polymer 2 displayed a 3D supramolecular network. [ABSTRACT FROM AUTHOR]

Abstract Organotin(IV) complexes involving two different dithiocarbamate groups: N -methyl- N -phenyldithiocarbamate (L1) and N -ethyl- N -phenyldithiocarbamate (L2) are reported. The complexes have been characterized using spectroscopic techniques and elemental analysis, and were represented as [(CH 3) 2 Sn 2 L1L2] (1) , [(C 4 H 9) 2 Sn 2 L1L2] (2) and [(C 6 H 5) 2 SnL1L2] (3). The crystal structures of [(CH 3) 2 Sn 2 L1L2] (1) and [(C 4 H 9) 2 Sn 2 L1L2] (2) are also reported. The structure indicated that both ligands bonded to the Sn atom by displacing the chloride ions from the organotin moiety. Complex (1) gave trigonal bypyramidal geometry; while a distorted skew trapezoidal-bipyramidal geometry occurred in complex (2). Thermal studies of the complexes by TG/DTG analysis showed that the stability of the complexes was influenced by the bond length/strengths of the tin-sulfur bonds. Although, no similarity in their decomposition pathways, all the complexes yielded tin sulfides as final residues. The complexes were screened for cytotoxic activity against HeLa cells and compared to the standard drug, 5-Fluorouracil (5FU). The result obtained showed that the complexes displayed better cyto-selectivity against the HeLa cell compared to the standard drug. Complex 1 gave the best IC 50 values compared to the rest of the complexes. The cytotoxic action displayed by the complexes showed their potential as anticancer agents. Graphical abstract Image 1 Highlights • Mixed ligand complexes of organotin(IV) were synthesized and characterized. • The crystal structures of two of the complexes were reported. • Both five and six coordinate geometries were observed in the complexes. • Cytotoxic studies of the complexes showed they have better activity than 5-Fluorouracil. [ABSTRACT FROM AUTHOR]

Abstract In this work we have reported two novel tetranuclear Cd(II) complexes viz. [Cd 4 (LOMe) 2 (μ 1,1 -N 3) 3 (μ 1,3 -N 3)] n (1) and [Cd 4 (LOEt) 2 (μ 1,1 -N 3) 3 (OAc)] 2 (2) where (H 2 LOMe) and (H 2 LOEt) are two important less explored salen-type Schiff base ligands. Both of the complexes have been characterized by using routine spectroscopic techniques, elemental analyses (C, H and N), X-ray powder diffraction pattern (PXRD) and thermal analysis by TGA along with single x-ray crystallography. The complete structural study discloses that in both cases the fully deprotonated ligand [LOMe]2- or [LOEt]2- utilized all potential coordination sites to accommodate four Cd(II) ions. Complex 1 is a one-dimensional polymer with azide (N 3) linkage having both (μ 1,1 end on) and (μ 1,3 end-to-end) azido bridging but complex 2 is a discrete octanuclear ensamble where two [Cd 4 (O) 4 (N) 2 ]2+ units bridged to each other showing μ 1,1 end on end on azide bridging. Exploration of photo physical properties in DMSO solvent reveals that Cd(II) complexes enhance appreciably the fluorescence behavior over free Schiff base ligands (H 2 LOMe) and (H 2 LOEt). DFT calculations performed at B3LYP/def2-TZVP level of theory reveal both the energetics and composition of FMOs in these complexes and also show electrophilic and nucleophilic areas via molecular electrostatic maps [ESP] concept. The antibacterial, membrane damage assay and anti -biofilm properties of complexes 1 and 2 were investigated very carefully against some important Gram-positive and Gram-negative bacterial strains. Graphical abstract Image 1 Highlights • Two Cd(II) complexes were synthesized and characterized. • Single X-ray crystallography. • DFT and TD-DFT calculations. • Photo physical properties of the complexes were investigated. • Antimicrobial and anti bio-film properties were evaluated. [ABSTRACT FROM AUTHOR]

Abstract Metal N-heterocyclic carbene (NHC) complexes have attracted considerable attention in biological fields for their potential applications in cancer and antimicrobial therapies. In this study, four new benzimidazole-based N-heterocyclic carbene salts (1a-d) and their silver (I) complexes (2a-d) were synthesized. All new compounds were characterized by elemental analysis, FT-IR, 1H NMR and, 13C NMR spectroscopy. Additionally, single crystal structural studies for complex 2d show that the benzene rings (C9 C14) and the central benzimidazole ring system make dihedral angles of 83.58(13)°. The Ag C l and Ag C single bond lengths are 2.3267(8) and 2.087(3) Å, respectively. The C Ag C l bond angle is 175.20(7)°. The prop-1-ene moiety attached at the second N-atom of benzimidazole is disordered at two set of sites with an occupancy ratio of 0.592(6): 0.408(6). There is one intramolecular hydrogen bond interaction between C22A-H22A ... N2. The salts and Ag-complexes were further evaluated for their in vitro anticancer activities against DU-145 human prostate cancer cells, MCF-7, MDA-MB-231 human breast cancer cells and L-929 non-cancer cell for 24 h, 48 h and 72 h using the MTT assay. The Ag(I) NHC complexes (2a-d) showed a dose and time-dependent cytotoxic activity against all cell lines. The IC 50 s for all Ag(I) NHC complexes lower than 1 μM for 72 h time points on cancer cells. The results showed that complex 2d exhibited the highest activity against all cancer cell lines studied. Further, the complexes had relatively higher cytotoxicity to cancer cells than to non-cancer cell lines. Graphical abstract Image 1 Highlights • N-heterocyclic carbene ligands (NHC) and their Ag(I) complexes have been synthesized. • All the ligands and complexes were characterized by spectroscopic methods. • All compounds have been applied for the anticancer activity on MCF-7, MDA-MB-231 and DU-145 cancer cells. • The Ag(I) NHC complexes showed a dose and time-dependent cytotoxic activity against all cell lines. [ABSTRACT FROM AUTHOR]

Abstract Five new metal complexes ML 2 [Where, M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) and L is (E)-(2-(2-hydroxybenzylidene)hydrazinyl)(pyridin-4-yl)methaniminium)] have been synthesized and characterized by elemental analysis, molar conductivity, magnetic moment and spectroscopy (UV–Vis, FT-IR and ESR) studies. The spectral data showed that ligand is tridentating coordination through azomethine nitrogen, methaniminium nitrogen and phenolic oxygen. DNA binding studies of transition metal complexes 1–5 were examined by electronic absorption spectroscopic techniques. All the metal complexes 1–5 have shown hypochromism. Photoluminescence activity of ligand L and its metal complexes 1–5 were carried out. The ligand L showed weak emission in π→π* and n→π* excitation. The complexes 1 , 2 and 4 didn't exhibited noticeable emission in three different excitation, complex 3 showed enhanced emission in π→π* and n→π* excitation and complex 5 showed enhanced emission in LMCT. Graphical abstract Image 1 Highlights • Synthesize of five novel transition metal complexes from methaniminium hydrazone Schiff base. • Prepared metal complexes were characterized by using various physico-chemical methods. • DNA binding studies of synthesized compounds have been ascertained. • Photoluminescent properties of ligand and its complexes were examined. [ABSTRACT FROM AUTHOR]

This article deals with the synthesis, structural characterization, and magnetic studies of heterometallic NiII/LnIII complexes. The article begins with an introduction on the phenomenon of single‐molecule magnetism and various types of molecular complexes that can function as molecular magnets. Among such complexes, 3d/4f combinations have been studied considerably, although examples involving NiII are considerably fewer than those involving ions like MnIII. In this article, we discuss how NiII can be profitably used to construct molecular magnets by describing features that allow this ion to exhibit magnetic anisotropy. Several examples of NiII/4f complexes drawn from the literature and our own work are described. In most of these complexes, NiII is six‐coordinate in a distorted octahedral geometry, while in one example NiII is four‐coordinate in a square‐planar geometry. The various ligands involved in assembling such diverse complexes are also discussed. In each case the magnetic properties of the complexes, including some SMM properties in particular, are discussed. In view of the isotropic nature of the GdIII ion with seven unpaired f electrons, some NiII/GdIII complexes possessing interesting magnetocaloric properties are also included. The synthesis and study of the single‐molecule magnet (SMM) properties of heterometallic Ni‐4f complexes with varying nuclearity are reviewed. [ABSTRACT FROM AUTHOR]

Abstract New nanometer Cu(II)-benzohydrazide complexes were synthesized and characterized. Mono negative tetra-dentate mode is the general feature proposed for all coordinating ligands. Variable structural forms were established, square-planer, tetrahedral and octahedral arrangements around copper centers. XRD and TEM studies displayed a nanometer size for crystalline compounds. TGA analysis of new complexes showed low thermal stability due to the presence of crystal water molecules. Kinetic parameters were calculated using two comparative methods for assertion. ESR study was performed on three chosen complexes to estimate essential spectral parameters and assert on proposed geometries. Gaussian09 software program and applying DFT/B3LYP method was used for optimizing all structures to give the best arrangement for atoms. Essential indexes were extracted from log files as well as other indexes were computed based on frontier energy gaps. Potential theoretical anti-inflammatory, antitumor and anti-allergic studies were executed using Autodock 4.2 tools. Essential energies were calculated over docking complexes corresponding to 5HN1, 5AV1 and 4H1L protein receptors for three pathogens (inflammation, liver cancer and allergy, respectively). H 2 L5 ligand displays significant activity towards inflammation and allergy diseases. Such potential feature will give a well insight about their biological attitude in future experimentation. Graphical abstract Unlabelled Image Highlights • New benzohydrazide -Cu(II) complexes • Tri-dentate mode of bonding was proposed • Spectral and analytical tools proposed the formulae • Gaussian09 program was implemented to optimize structural formula • Molecular docking using Auto Dock tools were utilized to explain the experimental behavior of the organic compounds [ABSTRACT FROM AUTHOR]

Graphical abstract A series of titanium(IV) complexes derived from (pyridin-2-ylalkyl)aniline have been synthesized and used as catalysts for the polymerization of 1,3-butadiene and isoprene in the presence of methylaluminoxane (MAO). Abstract A series of titanium(IV) complexes of general formula TiCl 3 [ N,N -(pyridin-2-ylalkyl)anilido, TiCl 3 L, 8 – 13 , were prepared by reactions of TiCl 4 with substituted (pyridin-2-ylalkyl)anilines, L H , and characterized by analytical and spectroscopic methods. Compound 10 was obtained by using TiI 4 as titanium precursor. In the case of L H = 2,6-diisopropyl(pyridin-2-ylmethyl)aniline, 1 , and 2,6-diisopropyl(pyridin-2-ylethyl)aniline, 2 , the intermediate formation of TiCl 4 L H , 6 – 7 , was detected, undergoing HCl elimination on heating to finally give 8 and 9. The products are not stable in coordinating solvents (thf, CH 3 CN). Ligand dissociation was observed from TiCl 3 (N,N -2,6-diisopropyl(pyridin-2-ylmethyl)anilido, 8 , resulting in the formation of Ti 2 OCl 6 (CH 3 CN) 4 and 2-(2,6-diisopropyl-phenylaminomethyl)pyridinium hexachlorotitanate. By reaction of TiCl 3 (thf) 3 or TiI 3 with 1 and 2 at ca 100 °C, the air sensitive derivatives TiCl 2 L, 14 , and TiI 2 L, 15 , were afforded. All titanium complexes were evaluated as catalysts for the polymerization of 1,3-butadiene and isoprene, in association with methylaluminoxane (MAO). The results indicate that the catalytic activity is strictly dependent on the nature of the ligands and the oxidation state of the metal, while the nature of the titanium complex has negligible influence on the selectivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A centrosymmetric copper(II) Schiff base complex has been Synthesized. • The Schiff base is trapped in its zwitterionic form. • Supramolecular interactions lead to the formation supra-molecular architecture. • Anion⋯anion interaction between the perchlorate anions have been analyzed. Abstract A centrosymmetric square planar bis-ligand copper(II) complex, [Cu(HL) 2 ](ClO 4) 2 , with a potential tetradentate Schiff base, HL = 2-(2-(ethylamino)ethyliminomethyl)-6-ethoxyphenol, containing pendant side arm, has been prepared and characterized by elemental and spectral analysis and single crystal X-ray diffraction studies. The potential tetradentate Schiff base is trapped in its zwitterionic form and shows a bidentate bonding mode. Several weak forces like hydrogen bonding and C H∙∙∙π interactions lead to the formation of supra-molecular architecture. The existence of an anion⋯anion interaction between the perchlorate anions have been analyzed using DFT calculations, the Bader's theory of atoms-in-molecules (AIM) and the non-covalent interaction index (NCI plot). The O⋯O distance is 2.848(2) Å. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A cooper complex with a tridentate ONO hydrazone was synthesized. • The hydrazone coordinates to the copper ion in the amido tautomeric form. • XRD reveals that the Cu(II) ion is in a distorted square pyramidal environment. • Calculated spectroscopic features show a good agreement with experimental data. • The anticancer activity of the complex is higher than the reported for cisplatin. Abstract The new copper complex, [Cu(HL)(OH 2) 2 ](NO 3), including the tridentate N-acyhydrazone derived from 4-hydroxy-benzohydrazide and 2-hydroxy-3-methoxybenzaldehyde, (H 2 L), has been synthesized and characterized in the solid state and in solution by spectroscopic (FTIR, Ra, UV–vis, EPR) methods. The results were compared with those obtained for the hydrazone ligand and complemented with computational methods based on DFT. The crystal structure of the complex has been determined by X-ray diffraction. It crystallizes in the triclinic P 1 ¯ space group with Z = 2. The Cu(II) ion is in a distorted square pyramidal environment, coordinated to a planar HL- anion acting as a tridentate ligand. The 5-fold coordination is completed with two water molecules. It is arranged in the lattice as H-bonded ribbon-like polymers that extends along the [1 2 1] crystal direction. The cytotoxicity of the complex together with that of the H 2 L ligand and the copper ion were evaluated in vitro against five different human cancer cell lines namely A549 (lung), MG-63 (bone), MCF-7 and MDA-MB-231 (breast) and Jurkat (leukemia). The copper complex inhibits the cell viability in a dose dependent manner with a greater potency than the H 2 L ligand and the free copper ion displaying even higher antitumor activity than the well-known anticancer metallodrug cisplatin. [ABSTRACT FROM AUTHOR]

Graphical abstract Straightforward synthetic methodologies for the preparation of bis(N,N′ -substituted oxamate) Zincate(II) complexes are discussed. The molecular solid state structures of two compounds are reported, confirming Bromine...bromine interactions. The emission spectra analyses for Zn(II) complexes show enhanced intensity and blue shifted emission compared to the free ligands. Electrochemical investigations indicate reversible electrochemical processes. DFT calculations reveal molecular electronic structure of the investigated compounds. Highlights • synthesis and characterization of bis(N,N′ -substituted oxamate) Zincate(II) complexes. • Computational calculations validate the electronic properties of the complexes. • Remarkable impact of the variation of the substituent on the luminescence properties. Abstract Treatment of two equivalents of N,N′ -bis(X-phenyl)oxamides (1) with one equivalent of [Zn(OAc) 2 (H 2 O) 2 ] (2) in the presence of four equivalents of [ n Bu 4 N]OH produce the corresponding bis(N,N′ -substituted oxamate) zincate(II) complexes with the general formula (n Bu 4 N) 2 [Zn(X-phenyloxamide) 2 ] (3) (a , X = 3-NO 2 ; b , X = 4-NO 2 ; c , X = 2,6 CH 3 ; d , X = 3,4-CH 3 ; e , X = 2-Br; f , X = 4-Br; g , X = 2-F; h , X = 4-F; i , X = 2-Cl; j , X = H). Complexes 3a – j have been characterized by elemental analysis, NMR (1H, 13C{1H}) and IR spectroscopy. In addition, 3a and 3f have been characterized by single crystal X-ray crystallography. The zinc (II) ion in the later complexes is four-coordinate with two ethanediamide-nitrogen atoms from two bidentate N,N′ -disubstituted oxamate ligands at each metal center. In addition, the calculated electrostatic potentials of 3f rationalize the formation of chain structures via the Br...Br interaction. Complexes 3a – j showed a characteristic LLCT (π → π*) band in the UV-Vis spectra, which was confirmed by TD-DFT calculations. DFT calculations show that the Zn(II) orbitals are neither contributing to the HOMO nor to the LUMO, i.e. the HOMO and LUMO are mainly located on the ligands. The emission spectra analyses for Zn(II) complexes 3a – j show enhanced intensity and blue shifted emission compared to ligands 1a − j. The cyclic voltammetry measurements of complexes 3a – j showed reversible electrochemical processes for the (N,N′ -substituted oxamate−2/−3) between −1.52 and −1.77 V using [N n Bu 4 ][B(C 6 F 5) 4 ] as the supporting electrolyte. It was found that the 3-nitro- (3a) and 4-nitro-functionalized (3b) derivatives resulted in a significantly higher Fc/Fc+ redox potential (E0′) compared to the more electron-rich 3, 4-dimethyl (3c) and 2,6-dimethyl (3d) derivatives. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Dinuclear copper(II) molecule. • X-ray diffraction study. • Catecholase activity. • Phenoxazinone synthase activity. Abstract [CuII 2 (L) 2 Cl 4 ] (1) [L = 2-(benzylthio)ethanamine] has been synthesized and characterized using spectroscopic and X-ray crystallographic results. Structural analyses reveal bidentate chelation behaviour of the neutral L having a distorted square pyramidal coordination environment around each copper(II) with one L, one chloride and two bridging chloro. 1 behaves as an effective catalyst towards oxidation of 3,5-di- tert -butylcatechol to its corresponding quinone with molecular oxygen and also the coupling of o -aminophenol to its phenoxazinone chromophore in methanolic solutions with turnover numbers 2.18 × 102 h−1 (catecholase activity, MeOH), and 3.60 × 102 h−1 (phenoxazinone synthase activity, MeOH) and 2.36 × 102 h−1 (Phenoxazinone synthase activity, MeCN). [ABSTRACT FROM AUTHOR]

Graphical abstract In quest of copper complexes having [CuN 3 O] cores, [Cu(phen)(L –Val)(H 2 O)]NO 3 (1) and [Cu(bpy)(L –Val)]ClO 4 (2) complexes have been synthesized and structurally characterized (phen = 1,10–phenanthroline; bpy = 2,2′–bipyridine). 1 possesses a distorted square-pyramidal, whereas 2 has a distorted square-planar coordination geometry. Structural features of both 1 and 2 reveal the formation of supramolecular networks via inter- and intra-molecular hydrogen bonding interactions. The mechanism of ligand substitution of 1 and 2 by thiourea (TU) is a biphasic process in which an initial fast and dissociative reaction is followed by a slower and associative one. It is concluded from the activation parameters that the difference in structure does not affect the mechanism. Complexes 1 and 2 have also been evaluated as functional models for the catechol oxidase enzyme and phenoxazinone synthese and they are promising candidates as functional mimics for catechol oxidase and phenoxazinone synthase. Highlights • Biomemicking of copper enzymes using mixed NO-ligands. • Effect of the structure on the biomimetic activity. • Stabilization of supramolecular networks via inter- and intra-molecular hydrogen bonding interactions in both complexes. Abstract In quest of copper complexes having [CuN 3 O] cores, [Cu(phen)(l –Val)(H 2 O)]NO 3 (1) and [Cu(bpy)(l –Val)]ClO 4 (2) complexes have been synthesized and structurally characterized (phen = 1,10–phenanthroline; bpy = 2,2′–bipyridine). Complex 1 possesses a distorted square-pyramidal, whereas 2 has a distorted square-planar coordination geometry. Structures of 1 and 2 have supramolecular networks formed via inter- and intra-molecular hydrogen bonding interactions. The kinetics and mechanism of ligand substitution of 1 and 2 by thiourea (TU) were studied in detail and showed a biphasic process in which an initial fast reaction is followed by a slower one. The activation parameters for the fast reaction: Δ H # = 68 ± 4 and 73 ± 5 kJ mol−1, Δ S # = 43 ± 10 and 54 ± 9 J K−1 mol−1 for 1 and 2 , respectively, supports a dissociative substitution mechanism. Whereas for the slow reaction: Δ H # = 33 ± 6 and 43 ± 3 kJ mol−1, Δ S # = −77 ± 10 and −56 ± 9 J K−1 mol−1 for 1 and 2 , respectively, support an associative substitution mechanism. It is concluded from the activation parameters that the difference in structure does not affect the mechanism. Complexes 1 and 2 have also been evaluated as functional models for the catechol oxidase enzyme and phenoxazinone synthase. The model complexes 1 and 2 show catecholase activity of K cat = 10.9 × 103 and 11.4 × 103 h−1 and phenoxazinone synthase activity of K cat = 2.1 × 103 and 4.3 × 103 h−1, respectively. Compared to the enzyme itself (K cat = 8.3 h−1), the model complexes 1 and 2 are promising candidates as functional mimics for catechol oxidase and phenoxazinone synthase. [ABSTRACT FROM AUTHOR]

Abstract A series of copper complexes with tripodal amine ligands was synthesized and structurally characterized. The copper(I) complexes of this series were investigated in regard to their reactivity towards dioxygen using stopped-flow techniques. For most complexes no "dioxygen adduct" complexes as intermediates could be detected. During the course of our investigations it was observed that the copper(II) complex with the ligand 3,3′-dimethylaminopropyl-(2-methylenpyridyl)-amine (Me 4 -p33) crystallized as a dinuclear complex, [Cu(Me 4 -p3H3)OH] 2 (ClO 4) 4 , that could be structurally characterized. Interestingly, it turned out that in crystalline form the two bridging hydroxide ions were intact while two of the amine arms of the two ligands were protonated. DFT calculations were performed to get a better understanding of the behavior of this complex system in solution. Further protonation of two more amine ligand arms in solution was possible, still keeping the bridging hydroxide ions in place in the solid state. A related copper(II) complex system could be crystallized that contained a coordinated carbonate anion together with a protonated amine arm. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Three novel water-soluble Cu(II)-based porphyrin complexes. • Various spectroscopic means showed CuP-1 has strongest binding affinity with CT-DNA. • MTT tests showed CuP-1 with good cytotoxicity to TCA8113, but weak for normal L929. Abstract Three Cu-complexes, one is containing 5-(4-Nitrophenyl)-10,15,20-tris (4- N -methylpyridinium) porphyrin ligand (labeled as CuP-1) and the others with meso-10,15,20-tris (4- N -methylpyridinium)-5-(4′- X- schiff base) porphyrin ligands (X referred to salicylaldehyde (CuP-2), o-Vanillin (CuP-3) respectively) have been successfully synthesized and well characterized. Various spectroscopic approaches indicate that three Cu-complexes could effectively bind with CT-DNA through intercalation mode, especially CuP-1 , which has better binding affinity than its analogs. Moreover, the antiproliferative activity of the delegate complex CuP-1 have been studied by MTT assay, and CuP-1 exhibits gratifying cytotoxicity towards TCA8113 (tongue squanmous carcinoma) cell lines. [ABSTRACT FROM AUTHOR]

Graphical abstract Three new tetranuclear square Cu(II) and Ni(II), [2 × 2] grid complexes comprising Symmetrical ditopic open chain ligands with terminal carboxylate/oxime functions and central pyrimidine ring are reported. These [2 × 2] square grids are dominated by intramolecular antiferromagnetic exchange coupling. Highlights • Synthesis of symmetrical ditopic open chain ligands with terminal carboxylate/oxime functions and central pyrimidine ring are reported. • Three new tetranuclear square Cu(II) and Ni(II), [2 × 2] grid complexes have been isolated and structurally characterized. • Reported complexes show dominantly intramolecular antiferromagnetic exchange coupling. • The reported ligands demonstrate the propensity for expanded cluster growth, if the right combination of donor components and reaction conditions are chosen. Abstract The successful synthesis of new pyrimidine based organic ligands with terminal carboxylate and oxime functional groups, followed by their employment in metallogrid self-assembly has yielded three tetranuclear [Ni 4 (L1) 4 ]∙2CH 3 CN∙4CH 3 OH·4H 2 O (1), [Cu 4 (HL1′) 4 ]∙8CH 3 OH·28H 2 O (2) and [Ni 4 (H 2 L2) 4 ](CF 3 SO 3) 8 ∙4CH 3 NO 2 ·8H 2 O (3), [2 × 2] metallogrid complexes. The complexes have been well characterized by elemental analyses, IR spectra, UV-vis spectra and X-ray structural analyses. Variable temperature magnetic measurements/studies done on these three complexes followed by magnetic data fitting suggest that all the three complexes are dominated by intramolecular antiferromagnetic exchange coupling. [ABSTRACT FROM AUTHOR]

Graphical abstract Two copper(II) complexes based on a rare nitronyl nitroxide with mixed N-containing heterocyclic rings were obtained, which displayed different magnetic properties. Highlights • A novel mixed N-containing heterocyclic rings nitronyl nitroxide is reported. • Two copper-radical complexes are synthesized. • The complexes display different magnetic properties. Abstract A new nitronyl nitroxide NIT-5Im-3Py (1) and its copper complexes [Cu(hfac) 2 ] 4 (NIT-5Im-3Py) 2 (2), [Cu(hfac) 2 NIT-5Im-3Py] n (3) (NIT-5Im-3Py = 2-(5-(1-imidazole)-3-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate) have been successfully synthesized and the molecular structures were elucidated by single-crystal X-ray structural analysis. In complex 2 , NIT-3Py-5Im acts as bridge ligand to link four Cu(II) ions leading to {Cu 4 } complex while complex 3 displays a 1D-chain structure. Magnetic studies show that antiferromagnetic interactions dominate in complex 2 , while there exist strong ferromagnetic interactions between Cu(II) and coordinated NO group in complex 3. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Various coordination modes were obtained by a PNP ligand with Cu, Ag, Pt, and Pd. • Complexes were characterized by X-ray Crystallography, 1H NMR, 31P{1H} NMR, HRMS, EA. • Absorption and luminescence behaviors were reported; NMR and MS data were discussed. Abstract Complexes of copper, silver, platinum, and palladium with N,N -bis[2-(diphenylphosphino)ethyl]-phenylamine (a PNP ligand) have been synthesized and characterized by 1H NMR, 31P{1H} NMR, HRMS, Elemental Analysis, and X-ray Crystallography. NMR data that were obtained at various temperatures resulted in different patterns in terms of peak multiplicity and coupling constants. Absorption and luminescence behaviors were reported, NMR and MS data were discussed and the coordination modes were investigated. The platinum complex that was synthesized in the present study was found to be a trans complex (by X-ray diffraction and 31P{1H} NMR data) contrary to the 31P{1H} NMR data for the cis isomer published last year in the literature by Kostas I. D. et al. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Three new dioxomolybdenum(VI) complexes are synthesized. • These complexes are tested as catalysts for cyclohexane oxidation. • Sebacic acid and FeCl 3 as acid auxiliaries are effective to promote the reaction. Abstract Three new dioxomolybdenum (VI) complexes, [MoO 2 L1(MeOH)] (1), [MoO 2 L2(MeOH)] (2) and [MoO 2 L3(H 2 O)]·EtOH (3), where L1, L2 and L3 are the dianionic form of N′-(2-hydroxybenzylidene)-3-methylbenzohydrazide, 4-bromo-N′-(2-hydroxybenzylidene)benzohydrazide and 2-bromo-N′-(2-hydroxy benzylidene)benzohydrazide, respectively, have been prepared and characterized by IR, UV–Vis and NMR spectra, as well as single crystal X-ray diffraction. The Mo atoms in the complexes are in octahedral coordination, with the ONO donor set of the hydrazone ligands, O atoms of the solvents, and two oxo groups. Crystals of the complexes are stabilized by hydrogen bonds of types O H⋯N and O H⋯O. Moreover, the catalytic properties of complexes 1 – 3 are compared in cyclohexane oxidation. It was found that sebacic acid and FeCl 3 could promote the catalytic activities of the complexes. [ABSTRACT FROM AUTHOR]

Graphical abstract Mixed ligand oxidovanadium(IV) complexes VO(ox)(im) 3 ·H 2 O (1), VO(ox)(4-mim) 3 (2), K 2 [VO(ox) 2 (2-mim)]·2H 2 O (3) and [V 2 O 2 (edta)(phen) 2 ]·11H 2 O (4) are isolated and the catalytic performances of 1 , 2 and 4 are tested for the degradations of methyl orange, showing the influence of dissociation ability of ligands and labile coordinated sites. Highlights • Mixed ligand oxidovanadium(IV) complexes are isolated. • EPR and theoretical calculations are consistent with the vanadium(IV) oxidation state. • Catalytic degradations for MO show the influence of dissociation ability of ligands. Abstract Mixed ligand oxidovanadium(IV) complexes VO(ox)(im) 3 ·H 2 O (1), VO(ox)(4-mim) 3 (2), K 2 [VO(ox) 2 (2-mim)]·2H 2 O (3) and [V 2 O 2 (edta)(phen) 2 ]·11H 2 O (4) (H 2 ox = oxalic acid, H 4 edta = ethylenediaminetetraacetic acid, im = imidazole, 2-mim = 2-methylimidazole, 4-mim = 4-methylimidazole, and phen = 1,10-phenanthroline) have been obtained at room temperature and under hydrothermal condition respectively. 1 – 3 feature bidentate oxalate with two carboxy oxygen atoms, and the dimeric complex 4 contains hexadentate edta as bridging ligand. 1 – 4 have been fully characterized by elemental, thermogravimetric and single crystal X-ray structural analyses, as well as IR, UV–vis and EPR spectroscopies. Moreover, 1 , 2 and 4 were tested for the catalytic degradations of methyl orange (MO) with H 2 O 2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Novel N-heterocyclic carbene silver(I) complexes. • Elemental analysis, FT-IR, 1H NMR and 13C NMR and X-ray crystallography techniques. • Anticancer activities on prostate and breast cancer cells and L-929 normal cells. • Selectivity for human cancer cells and non-cancer cells. Abstract In this study, we synthesized four novel unsymmetrically substituted NHC ligands (1a-d) and their Ag(I) complexes (2a-d). All new compounds were characterized using elemental analysis, FT-IR, 1H NMR, and 13C NMR spectroscopy and X-ray crystallography. The molecular structure of complex 2d was elucidated through single crystal X-ray diffraction analyses. Single crystal structural studies for complex 2d show that the benzene rings (C9–C14) and the central benzimidazole ring system make dihedral angles of 85.65(11)°. The Ag–C l and Ag–C single bond lengths are 2.3553(7) and 2.096(2) Å, respectively. The C–Ag–C l bond angle is 168.27(7)°. Both salts and complexes were tested for their anti-cancer potential against three human cancer cell lines (DU-145, MCF-7, and MDA-MB-231) and non-cancer cells adipose from mouse (L-929) for 24 h, 48 h and 72 h using the MTT assays. However, the Ag(I)–NHC complexes (2a-d) showed a dose and time-dependent cytotoxic activity against all cell lines. MDA-MB-231 human breast carcinoma cells were the most sensitive to the Ag(I)–NHC complex displaying IC 50 lower than 1 μM all time points. Further, the IC 50 s for Ag(I)–NHC were higher in non-cancer cells, suggesting that complexes possessed noteworthy selectivity for human cancer cells. [ABSTRACT FROM AUTHOR]

Graphical abstract Synthesis and characterization of sterically hindered cobalt(II) β-ketoiminate complexes. Steric bulk introduces significant distortion in Co(Ldipp) 2 and leads to high spin pseudo-tetrahedral and low spin pseudo-square planar geometries. Abstract The reactions of cobalt(II) chloride with α,β-unsaturated-β-ketoamines, CH 3 C(O)CH C(NHR)CH 3 , where R = -phenyl, HLPh; R = -mesityl, HLmes; R = -2,6-diisopropylphenyl, HLdipp, and sodium hydride in THF solvent under anaerobic conditions affords brown or orange crystals of Co(Lph) 2 , Co(Lmes) 2 and Co(Ldipp) 2 , respectively. In THF/acetonitrile solvent mixture, the complexation reactions are not successful as unreactive salts containing networks of acetonitrile-coordinated sodium cations and the respective anions are formed. One of them, the sodium salt of HLdipp, is isolated and characterized as [Na(Ldipp)(CH 3 CN)] 4. Single-crystal X-ray diffraction data for the cobalt(II) complexes reveal that the metal centers assume distorted tetrahedral geometries. The degree of distortion increases with the size of the substituents present in the phenyl groups: Co(Lph) 2 < Co(Lmes) 2 < Co(Ldipp) 2. Crystallographic data measured at 296, 200, 150 and 100 K for Co(Ldipp) 2 reveal that it exists as two geometrical forms, namely, distorted tetrahedral and distorted square-planar. The data also indicate that the pseudo-tetrahedral to distorted square-planar transition is favored at lower temperatures. Electrochemical data measured in THF and DCM solvents reveal the likely presence of Co(II)-solvent interaction in Co(Lph) 2 and Co(Lmes) 2 and no such interaction in Co(Ldipp) 2. Magnetic susceptibility data for Co(Ldipp) 2 in the 4–300 K temperature region reveal spin-crossover at ca. 130 K. Qualitatively, the magnetic and crystallographic data complement each other with respect to the presence of the high spin pseudo-tetrahedral and low spin pseudo-square planar geometries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Complexes of Sn(IV)-tetra(4-sulfophenyl)porphyrin with antioxidants (methoxydol and ionol) and their precursors (para-cresol and 3-hydroxypyridine) were synthesized and characterized. • Fluorescent properties of the diphenol complexes of Sn(IV) porphyrins and their photochemical stability in the presence of hydrogen peroxide in buffer media were investigated. Abstract Complexes of Sn(IV)-tetra(4-sulfophenyl)porphyrin with antioxidants (methoxydol and ionol) and their precursors (para-cresol and 3-hydroxypyridine) were synthesized. All four complexes were obtained by boiling in aqueous solutions of the p-sulfo substituted Sn(IV) dihydroxytetraphenylporphyrin with the corresponding phenols. The structure of the obtained compounds was confirmed by NMR spectroscopy and mass spectrometry methods and quantum chemical calculations. Fluorescent properties of the diphenol complexes of Sn(IV) porphyrins and their photochemical stability in the presence of hydrogen peroxide in buffer media were investigated. It was shown that complexes with antioxidant ligands (ionol and methoxydol) have higher quantum yields and are more resistant to macrocycle destruction than complexes with other phenols and Sn(IV) dihydroxytetraphenylporphyrinate complexes. The main reasons for higher stability and weak quenching of fluorescence intensity are the presence of alkyl groups in the ortho -positions of the phenolic rings in the ionol and methoxydol molecules. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Bis-heteroleptic Ru(II) complex with 2-picolinamide (H 2 pia) was prepared. • [Ru(bpy) 2 (H 2 pia)]X 2 (X− = Cl− or OTf−) were analyzed by crystal structure and 1H NMR. • Two amide H atoms of H 2 pia can bind Cl− or F− in separate steps with color change. • Visible color change upon forming the F-adducts and F− removal by adding Li(OTf). Abstract Cis -[Ru(bpy) 2 (OH 2) 2 ](OTf) 2 (1 ·(OTf) 2 ; OTf− = CF 3 SO 3 −) was reacted with 2-picolinamide (H 2 pia) in EtOH to form bis-heteroleptic complex [Ru(bpy) 2 (H 2 pia)]X 2 (2 ·X 2 ; X− = OTf− or Cl−). Crystal structures of 2 ·X 2 revealed that H 2 pia was coordinated to Ru(II) through N of pyridyl group and O of amide group to form the N,O -coordination, and acted as a neutral ligand. Bond distances around the amide group and 1H NMR study for 22+ suggested that π -electron on the carbonyl group was delocalized to the whole amide group. Adding F− to the acetonitrile solution of 2 ·(OTf) 2 changed the red solution to dark-red due to the transportation of π -electron on the amide group by the bound F− to the amide H. Absorption and 1H NMR spectroscopies revealed that the NH 2 of 22+ undergoes selective two-step adduct reaction with F−: the H close to pyridyl group of H 2 pia first formed a 1:1 adduct (mono-F-adduct- 22+), followed by the other H forming the 1:2 adduct (di-F-adduct- 22+). Adding excess Li(OTf) to these F-adduct- 22+ solutions changed the dark-red solution back to red, suggesting that the adducted F− was removed by Li+ to form 22+ and LiF. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hexanuclear heterometallic (FeIII 2 LnIII 4) (LnIII = GdIII; TbIII; DyIII and HoIII) complexes are described. • Magnetic studies reveal predominantly antiferromagnetic interactions among the paramagnetic metal centers. • Magnetic anisotropy is present in all the complexes except the GdIII analogue. • Mössbauer measurements confirm the non-magnetic ground state of the central FeIII 2 fragments) in these complexes. • ac Susceptibility measurements upto to 2 K do not reveal the presence of an out-of-phase signal. Abstract Hexanuclear heterometallic (FeIII 2 LnIII 4) (LnIII = GdIII; TbIII; DyIII and HoIII) complexes in a butterfly-shaped core are described. Two of the FeIII ions form part of the body and a pair of lanthanides are present in the wings. Detailed magnetic studies of all the complexes have been carried out which reveal predominantly antiferromagnetic interactions among the paramagnetic metal centers. The M vs H/T plots show the presence of magnetic anisotropy (except for the GdIII analogue) in these complexes. On the other hand, ac susceptibility measurements down to 2 K do not reveal the presence of an out-of-phase signal. Mössbauer measurements confirm the non-magnetic ground state of the central FeIII 2 fragments and absence of the transfer field from the DyIII to FeIII. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • New olefin-tethered organoruthenium carbene complexes have been synthesized and epitomized. • X-ray studies confirmed an octahedral geometry of the new complexes. • The newly synthesized complexes catalyze the hydrogenation of esters efficiently. Abstract A series of Ru(II) complexes encompassing imidazolylidene olefin arm have been designed. The newly synthesized ligands and complexes were fully characterized by 1H, 13C NMR, and elemental analyses. Structural geometry for one of the envoy Ru(II) carbene complexes 3a was confirmed by single-crystal X-ray diffraction studies. The complexes acquired a distorted octahedral geometry. The highly active [Ru(II)-NHC] complex 3b , showed excellent catalytic performance for the hydrogenation of esters in 1,4-dioxane medium. The effects of solvent, base, wingtip substituents, time and catalyst loading were also investigated. The reported catalyst performed exceptionally well for a range of esters and furnishes very good yield of hydrogenated products. [ABSTRACT FROM AUTHOR]

Graphical abstract Two coordination polymers constructed from 3,5-bis(-carboxy-phenoxy) benzoic acid 1,5-bis(imidazol-l-yl)-benzene(bib) with Cd(II) in different solvents and investigated the influence of reaction temperature on the structure of the resultant complexes. Fluorescence test results show that these two complexes can be used as fluorescent probes to selectively detect and identify Fe3+ ions in water. Highlights • Synthesized two structurally different Coordination polymers in the same reactants. • An excellent luminescent property of coordination polymers was prepared. • Two complexes can be used to selectively detect and identify Fe3+ ions in water. Abstract Tricarboxylic acid 3,5-bis(-carboxy-phenoxy) benzoic acid (H 3 BCPBA) 1,5-bis(imidazol-l-yl)-benzene(bib) ligands and cadmium nitrate were used to synthesize two new metal–organic frameworks with different structure under the hydrothermal and solvent thermal conditions, namely [Cd(HBCPBA)(bip)] n (1) and [Cd 2 (HBCPBA) 2 (bip) 0.5 ] n (2). We determined the structure of two metal-organic frameworks by XRD, and characterized their structures by TG and powder X-ray diffraction (PXRD). Also we tested the fluorescence properties of the two coordination polymers at room temperature. The results showed the Complex 1 crystallizes in the Hexagonal space group P 6 5 , with tentacle structure. Complex 2 crystallizes in the Monoclinic space group P 2 1 / c , with a layer of three interdigitated structure. Fluorescence test results show that these two complexes can be used as fluorescent probes to selectively detect and identify Fe3+ ions in water. [ABSTRACT FROM AUTHOR]

Graphical abstract Synthesis, characterization and reactivity studies of two dual-site aqua Ni(II) complexes 1 and 2 supported by non-heme N , N′ -dimethyl- N,N′ -di(quinolin-8-yl)cyclohexane-1,2-diamine and N , N′ -di(quinolin-8-yl)cyclohexane-1,2-diamine have been investigated. The crystal structures of 6 and 8 are discussed. Compound 2 on addition of hydrogen peroxide and a base a new intermediate 2a is detected which undergo nucleophilic deformylation of 2-phenylpropionaldehyde. Catalytic oxidation of cumene and ethylbenzene by 1 and 2 afforded hydroxylated products in high yeilds. Highlights • Two dual site aqua Ni(II) complexes 1 and 2 supported by non-heme ligands have been studied. • The phen and en incorporated 3 – 8 were obtained by substituting two waters coordinated to Ni(II) ion. • Crystal structures of 6 and 8 are described. • Compound 2 with H 2 O 2 /base forms an intermediate 2a which undergo nucleophilic deformylation of 2-phenylpropionaldehye. • Compounds 1 and 2 showed catalytic hydroxylation of cumene and ethylbenzene. Abstract Mononuclear compounds [Ni(BQCNMe 2)(H 2 O) 2 ](ClO 4) 2 1 and [Ni(BQCNH 2)(H 2 O) 2 ](ClO 4) 2 2 of N , N′ -dimethyl- N , N′ -di(quinolin-8-yl)cyclohexane-1,2-diamine (BQCNMe 2) and N , N′ -di(quinolin-8-yl)cyclohexane-1,2-diamine (BQCNH 2) were synthesised and characterized by elemental analysis, IR/UV-Vis spectroscopy, cyclic voltammetry (CV)/differential pulse voltammetry (DPV) and X-ray powder pattern. [Ni(BQCNMe 2)(en)](ClO 4) 2 3 and [Ni(BQCNMe 2)(phen)](ClO 4) 2 4 were prepared by reacting 1 with ethylenediamine (en) and 1,10-phenanthroline (phen) respectively while [Ni(BQCNH 2)(en)](ClO 4) 2 5 and [Ni(BQCNH 2)(phen)](ClO 4) 2 6 were obtained from the reaction of 2. Compounds [Ni(BQENMe 2)(en)](ClO 4) 2 7 and [Ni(BQENH 2)(en)](ClO 4) 2.CH 3 CN 8 (BQENMe 2 is N,N′ -dimethyl- N,N′- bis(8-quinolyl)ethane-1,2-diamine) and BQENH 2 is N,N ′-bis(8-quinolyl)ethane-1,2-diamine) were synthesised similarly. Compounds 6 and 8 were characterized by single crystal X-ray diffractometry and their structural features are presented. The reactivity of 2 with H 2 O 2 /base was investigated. A new peak at 570 nm in the UV-Vis spectrum corresponding to 2a was obtained which on addition of 2-phenylpropionaldehyde (2-PPA) decays giving pseudo-first order rate constant of 9.2 × 10−3 s−1 and acetophenone as a major product. The catalytic hydroxylation of cumene and ethylbenzene by 1 and 2 in the presence of meta -chloroperbenzoic acid (m -CPBA) was investigated. [ABSTRACT FROM AUTHOR]

Derivatisation of Grignard synthons "PhAeI(thf)n" (Ae = Mg‐Ba) prepared in situ from reactions of metal filings and iodobenzene provides a one‐pot synthesis of heteroleptic N donor alkaline earth iodide complexes. Protolysis of "PhAeI(thf)n" with 3,5‐diphenylpyrazole (Ph2pzH) yields pyrazolate complexes [Mg2(µ‐Ph2pz)2(I)2(thf)3] (1), [Ae(Ph2pz)(I)(thf)4] (Ae = Ca (2), Sr (3)), and [Ba2(Ph2pz)2(µ‐I)2(thf)8] (4). Addition of the Ae‐Ph moiety to carbodiimide MesN=C=NMes (Mes = 2,4,6‐(CH3)3C6H2) gave a series of benzamidinate iodide complexes [Ca2{(MesN)2CPh}2(µ‐I)2(thf)4] (6), [Sr{(MesN)2CPh}(I)(thf)4] (7), and [{Ba{(MesN)2CPh}(µ‐I)(thf)3}∞] (8). By contrast a symmetrical magnesium complex [Mg{(MesN)2CPh}2(thf)] (5) was obtained by Schlenk redistribution. These syntheses proceed without pre‐activation of the metal for strontium and barium, and after activation with 2 mol‐% iodine for calcium. The heavy alkaline earth metal complexes are the first examples of heteroleptic halide pyrazolate or amidinate complexes for strontium and barium. Complexes 1, 3, 4 and 6–8 were characterised crystallographically, revealing diverse structural chemistry of heteroleptic amidinate and pyrazolate iodide complexes across the alkaline earth series. A highlight is [Ba{(MesN)2CPh}(µ‐I)(thf)3]∞ (8) – an iodide bridged infinite 1‐D polymer. Heavy Grignard reagents "PhAeI(thf)n" can be protolysed by pyrazoles to yield pyrazolate iodide complexes or add to carbodiimides to give benzamidinate iodide complexes. PhAeI(thf)n' is straightforward to prepare and its derivatisation enables direct access to bifunctional alkaline earth complexes from the metal. X‐ray characterisation has enabled structural comparisons across the Ae series (Mg‐Ba) for new heteroleptic iodide complexes. [ABSTRACT FROM AUTHOR]

With the 30 years old first example of a stable group 4 metallocene bis(trimethylsilyl)acetylene (btmsa) complex Cp2Ti(η2‐btmsa) a series of similar complexes like Cp′2M(η2‐btmsa) (M = Ti, Zr; Cp′ = Cp, Cp* as η5‐pentamethylcyclopentadienyl and Cp′2 = rac‐(ebthi) as rac‐1,2‐ethylene‐1,1′‐bis(η5‐tetrahydroindenyl)) represent excellent sources for the generation of the very reactive coordinatively and electronically unsaturated complex fragments [Cp'2M], which were used in many synthetic and catalytic reactions. Examples for this were oresented in several papers and summarized in some reviews. In this update new reactions of group 4 metallocene bis(trimethylsilyl)acetylene complexes towards symmetrically and unsymmetrically α‐dihetero‐substituted alkynes, reactions with other alkynes, di‐ and polyynes to metallacyclopentadienes as well as the conversions of the formed products are summarized. Additionally, novel synthetic applications of the formed metallacyclopentadienes on the basis of the zirconocene bis(trimethylsilyl)acetylene complex Cp2Zr(py)(η2‐btmsa) are highlighted. Reactions with imines, neutral N‐donor ligands, E‐H compounds (E = N, O, P), molecular hydrogen, water, phosphino‐ and aminoboranes, E‐Cl compounds (E = C, P), disilylated germylenes and aryloxy ketones were described. Different self‐assembly reactions to multinuclear complexes by using group 4 metallocene bis(trimethylsilyl)acetylene complexes in C‐C coupling reactions with or without C‐H bond activation to tri‐ or tetranuclear complexes are considered, too. These examples are discussed following the general L‐M‐S principle for stoichiometric and catalytic reactions, whereby different ligands L (L = Cp′ = Cp, Cp*, rac‐ebthi), metals M (M = Ti, Zr, Hf) and substrate substituents S influence the reactivity and the obtained products. An old dog learns new tricks: Group 4 metallocene bis(trimethylsilyl)acetylene complexes Cp′2M(X)(η2‐btmsa) are excellent sources to generate the very reactive complex fragments [Cp'2M]. α‐Heterosubstituted alkynes, di‐ and polyynes, imines, N‐donors, E‐H‐ and E‐Cl‐compounds, hydrogen, water, phosphino‐ and aminoboranes, germylenes, aryloxy ketones, and N‐heterocycles gave many novel products. [ABSTRACT FROM AUTHOR]

Ligands such as N‐2‐pyrimidylimidoyl‐2‐pyrimidylamidine (Pm2ImAm) possess both a bidentate and tridentate coordination site within a single ligand framework. Taking advantage of this, two tetranuclear complexes with manganese ([MnIIIMnII3(Pm2ImAm)3Cl6]) and iron ([FeIII4(Pm2ImAm)3Cl9]) have been isolated, characterized by single‐crystal X‐ray analysis, and their magnetic properties have been investigated through SQUID magnetometry and Mössbauer spectroscopy. As well, a mononuclear ([FeIII(Pm2ImAm)Cl3]) and binuclear ([MnII2(µ‐Cl)2(Pm2ImAm)2Cl2]) complex employing this ligand framework were also isolated, characterized by single‐crystal X‐ray analysis and their magnetic properties were investigated. For comparison purposes, the previously reported mononuclear complexes [MnIII(Py2ImAm)3] and [FeIII(Py2ImAm)3] were also probed here via SQUID magnetometry due to the similarities between these mononuclear systems and fragments of the tetranuclear complexes. Through this approach, clear interpretation of the magnetic properties in [MnIIIMnII3(Pm2ImAm)3Cl6] and [FeIII4(Pm2ImAm)3Cl9] was achieved. These results reveal that employing our N‐imidoylamidine ligands facilitates the rational design of polynuclear complexes with differing metal ion spin states. Rational design of tetranuclear complexes with manganese and iron was achieved by employing N‐imidoylamidine ligands. Evaluation via SQUID magnetometry and Mössbauer spectroscopy reveal a unique combination of low and high spin states for the metal centers within these cluster aggregates. [ABSTRACT FROM AUTHOR]

Highlights • Core-shell structured inorganic nanocomposite as photocatalyst. • Photocatalytic reduction of CO 2 to methanol under visible light. • Ni/NiO core-shell structured semiconductor as photoactive support. • Selective reduction of CO 2 to methanol. • Consistent efficiency and facile recovery for recycling. Abstract The present paper describes the first successful synthesis of an inorganic nanocomposite by grafting of cobalt (II) phthalocyanine (CoPc) on the core-shell Ni/NiO (NNO) semiconductor for the photocatalytic reduction of CO 2 to methanol under visible illumination using triethylamine as a sacrificial donor. The synthesised photocatalyst exhibited a remarkable enhancement in the yield of methanol as compared to the semiconductor Ni/NiO and CoPc for CO 2 reduction under identical conditions. The maximum yield of methanol was found to be 3641.2 μmol/g with the conversion rate of 151.7 μmol g−1 h−1 which was much higher than that observed with CoPc and semiconductor alone under identical experimental conditions. Furthermore, the synthesised nanocomposite showed superior activity as compared to the previously reported organic semiconductor bound cobalt complex photocatalyst. The composite photocatalyst was found to be highly stable which showed consistent recyclability for four runs without any significant loss in activity. [ABSTRACT FROM AUTHOR]