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Antimicrobial photodynamic therapy offers significant benefits over standard antibiotic therapy in terms of rapid sterilization and resistance reduction. In this paper, a series of ruthenium complexes were designed and synthesized for antibacterial studies. [Ru(tpy)(dppz-R)Cl][PF6] (tpy = 2,2′:6′,2′′-terpyridine; dppz = dipyrido [3,2-a:2′,3′-c] phenazine; R = H, CH3, C(CH3)3, F, CF3, NO2, NH2 or CN), Ru1–Ru8 all showed superior in vitro antimicrobial effects under blue light irradiation. Ru2 has the best antimicrobial activity, with its inherent dark toxicity and photodynamic inactivation rapidly killing S. aureus without developing drug tolerance. Binding and damaging DNA as well as generating ROS may be its potential antimicrobial targets. Ru2 lacks a hemolytic effect on rabbit erythrocytes and has low phototoxicity against G. mellonella Larvae. In addition, Ru2 has been successfully used to treat skin wounds in mice infected with S. aureus. Therefore, Ru2 has shown great potential as a photodynamic antimicrobial agent against the threat of S. aureus infection. [ABSTRACT FROM AUTHOR]

The diversity of catalytic activities and antioxidant properties of cerium oxide nanoparticles (CeO2 NPs) makes them promising materials for the theranostics of various diseases, especially those caused by disturbances in free radical homeostasis in living systems. Despite the fact that the functionalisation of nanoparticles' surface plays a critical role in nanomedicine applications, the effect of different coatings on their enzyme-like behaviour and antioxidant properties is still poorly understood, which limits the biomedical application of CeO2 NPs. This paper reports on the effect of low and high molecular weight biocompatible ligands on the SOD-like activity and radical scavenging properties of CeO2 NPs, which was analysed using a phosphate-rich medium resembling a natural environment. The results obtained show that these ligands modulate the SOD-like properties of CeO2 NPs as follows. Citrate and polysaccharide (maltodextrin and dextran) surface coatings increase the SOD-like activity of CeO2 NPs by an average of 2.2 times, and the protein corona (γ-globulin, γ-IgG) increases this activity by an average of 1.8 times. Citrate-coated CeO2 NPs and CeO2 nanoparticles modified with polysaccharide molecules are more effective SOD mimetics than CeO2@γ-IgG NPs. The SOD-like activity of phosphatidylcholine-coated CeO2 and CeO2@γ-IgG NPs is due to the combined action of nanoscale CeO2 and ligands. The antioxidant activity of CeO2 NPs after their modification with different ligands with respect to alkyl peroxyl radicals is multidirectional. Unexpectedly, citrate-, maltodextrin- and dextran-coated CeO2 NPs are more effective antioxidants than bare CeO2 NPs. CeO2 NPs modified with phosphatidylcholine or γ-IgG exhibited less radical-scavenging ability than bare CeO2 nanoparticles. Thus, common biocompatible ligands are able to regulate the biochemical activity of CeO2 NPs. [ABSTRACT FROM AUTHOR]

The π⋯π interactions in spin crossover (SCO) complexes can be used as an important means to fine-tune the spin transition behaviors. In this paper, three novel isostructural 2D Hofmann-type frameworks, [Fe(ppo)2M(CN)4] (1, M = Pt2+; 2, M = Pd2+; 3, M = Ni2+) have been successfully synthesized by judiciously choosing a large conjugated molecule, 2-(2-pyridyl)-5-(4-pyridyl)-1,3,4-oxadiazole (ppo) as the axial ligand. Single crystal X-ray crystallography analysis showed that there are different π⋯π interactions between the axial ppo ligands in 1–3. Variable temperature magnetic susceptibility studies revealed that 1 and 3 displayed incomplete and gradual SCO behaviors with T1/2 = 94 and 78 K, respectively, while 2 stayed in a high-spin state in the measured temperature range. The stronger π⋯π interactions between the conjugated ppo ligands observed in 1 and 3 than those in 2 may result in their different magnetic behaviors. [ABSTRACT FROM AUTHOR]

In this study, we synthesized two unsymmetrical and dipodal Schiff–Mannich combo ligands, namely benzoic acid (3-benzoimidazol-1-ylmethyl-2-hydroxy-5-methyl-benzylidene)-hydrazide (H2BBH) and the hydroxyl analogue 2-hydroxy-benzoic acid (3-benzoimidazol-1-ylmethyl-2-hydroxy-5-methyl-benzylidene)-hydrazide (H3BSH), for the selective detection of Zn2+ in semi-aqueous media. Both the probes selectively depict a turn-on response to Zn2+ as a result of the combined effect of chelation-induced enhanced fluorescence (CHEF) and photo-induced electron transfer (PET). Detailed experimental studies reveal that H2BBH and H3BSH can detect Zn2+ in solutions with limit of detections of 27 nM and 46 nM, respectively. The structures of probe-Zn2+ ensembles were proposed as [(HBBH)2Zn] and [(H2BSH)2Zn] by ESI-MS, FT-IR spectroscopy, 1H NMR titration and DFT/TD-DFT methods. Moreover, both the probes were successfully employed in the detection of Zn2+ in HuH-7 cells, seedlings of chickpea and mung beans, and paper strips. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed oxidative homocoupling reactions of aryl boronic acids using a solvent-free and ligand-free ball-milling method have been reported. These reactions allow simple, fast, and efficient synthesis of a series of biphenyl-derived organic fluorescent materials in modest and good yields without the use of ligands in air. The new organic fluorescent material N-[4-(4-{phenyl[4-(triphenylvinyl)phenyl]amino}phenyl)-phenyl]-N-[4-(triphenylvinyl)phenyl]aniline (B6) shows typical aggregation-induced emission features and reversible mechanical force responsive fluorescent properties. [ABSTRACT FROM AUTHOR]

Three silyl [PSiP] pincer cobalt(II) chlorides 1–3 [(2-Ph2PC6H4)2MeSiCo(Cl)(PMe3)] (1), [(2-iPr2PC6H4)2MeSiCo(Cl)(PMe3)] (2) and [(2-Ph2PC6H4)2MeSiCo(Cl)(LSi:)] (LSi: = {PhC(NtBu)2}SiCl) (3) were synthesized and used as catalysts and their catalytic activity for dinitrogen silylation was studied. Among the three complexes complex 3 was new and was synthesized via the reaction of [PSiP] pincer preligand L1 with CoCl2 in the presence of chlorosilylene via Si–H bond cleavage. The molecular structure of 3 was determined by single crystal X-ray diffraction analysis. Compared to complex 1, complex 2 is the more effective catalyst for dinitrogen silylation and 363 equiv. of N(SiMe3)3 could be reached per Co atom. Further study indicates that using the silylene ligand in complex 3 instead of the PMe3 ligand in complex 1, the catalytic activity of 3 is lower than that of 1. The catalytic mechanism for this catalytic system is proposed with the support of experimental evidence. The [PSiP] pincer cobalt(I) dinitrogen complex was proposed as the active catalyst for dinitrogen silylation. [ABSTRACT FROM AUTHOR]

As phenanthroline (phen) possesses great coordination ability with various ions, the development of new chiral phen ligands is in great demand in asymmetric catalysis. Herein, we rationally designed and developed an entirely new class of C2-symmetric rigid-featured chiral phen ligands that provide the N,N,O,O-tetradentate coordination of the phen moiety and two additional N,N-dioxides. The chiral ligands, termed Phen-2NO ligands, incorporate the advantages of both the phen skeleton and the pyrroloimidazolone-based N-oxide moiety, and their electronic and steric properties can be readily tuned through the incorporation of substituents in the aromatic rings of the amide group. These ligands presented a superior performance in the Ni(II)-catalyzed asymmetric Michael-type Friedel–Crafts alkylation reaction of indoles with β,γ-unsaturated α-ketoesters. Excellent yields (up to 93%) and high enantioselectivities (up to 99% ee) are obtained for a wide range of substrates under mild conditions. These results demonstrated the promising potential of the Phen-2NO ligand as an efficient chiral phen ligand. [ABSTRACT FROM AUTHOR]

Ruthenium arene-based complexes have attracted growing interest in overcoming the lack of efficiency of platinum-based chemotherapeutic drugs. Herein, we prepared two pyrazolyl-pyridine type bidentate ligands using 2-acetyl pyridine with biphenyl-4-carbaldehyde and 1-pyrene carbaldehyde. The isolated ligands were utilized to prepare two new Ru(p-cymene) complexes, [Ru(η6-p-cymene)(bpy)Cl]PF6 (Ru-bpy(1)) and [Ru(η6 -p-cymene)(pyn)Cl]PF6 (Ru-pyn(2)) and characterized well. Single-crystal X-ray diffraction analysis of Ru-bpy(1) revealed that the complex adopts pseudo-octahedral geometry. The MTT assay was performed on human breast carcinoma (MCF-7), cervical carcinoma (HeLa-S3) and lung adenocarcinoma (A549) cells to determine the in vitro cytotoxicity of the complexes. Although the complexes were found to be insensitive to cervical and lung cancer cells at concentrations of up to 100 μM, both the complexes showed efficient cytotoxicity in breast cancer cells. Moreover, these complexes exhibited apoptosis-inducing activity and cell-free antioxidant activity. [ABSTRACT FROM AUTHOR]

We report a novel triangular trinuclear copper(II) complex with a central μ3-OH bridge, [(CuL)3(μ3-OH)(ClO4)2]·CH3OH·H2O (1), stabilised by the oxime-based Schiff base ligand, 3-(((5-bromothiophen-2-yl)methylene)hydrazineylidene)butan-2-one oxime (HL). Comprehensive characterization of 1 has been realised through different analytical and physical methods coupled with spectroscopic techniques. 1 has been structurally characterised by single crystal X-ray diffraction. The antiproliferative capacity of HL and 1 has been evaluated against human lung cancer cell line A549. Compound 1 shows promising efficacy in contrast to HL, which shows a limited cytotoxicity. Contrary to HL, 1 has distinctly impeded the proliferation of lung adenocarcinoma A549 cell lines in a dose-dependent way. Compound 1 has been employed as a potential therapeutic agent for promising cellular transformation of malevolent A549 cell lines. The programmed cell death mechanism of 1 reveals characteristic apoptotic changes in cellular morphology like chromatin condensation, fragmented nuclei, nuclear shrinkage along with blebbing, elevated number of nuclear body fragments and distorted nucleus, while round, clear edged, intact nucleus and uniformly stained round nuclei have been observed in the negative control. Variable-temperature magnetic studies show an antiferromagnetic Cu⋯Cu coupling of −44.6(2) cm−1. The g value as determined by EPR measurement of 1 in frozen N,N-dimethylformamide solution corroborates the experimental magnetic susceptibility values. [ABSTRACT FROM AUTHOR]

Tridentate bis(carboxamide) pincers are key ligands used in catalysis, investigational medicinal inorganic compounds, and materials science. This study examined the atropisomerism of a group of bis(carboxamide) pincers with C2 symmetry to elucidate their physical, chemical, and structural behaviour, paving the way for the application of their metal complexes in different fields. One of the five compounds structurally elucidated by X-ray crystallography, 1c, has a pair of intramolecularly constrained isoquinoline ring substituents and crystallized enantiomerically pure in a chiral Sohncke space group. PM6 calculations of the 3-D potential energy surface for the main atropisomerisation reaction coordinate of 1c indicated that the lowest-energy conformer (atropisomer) has the isoquinoline rings canted out-of-plane by almost +30° and −30° relative to the central pyridine ring. The X-ray structure of 1c is located close to this energy minimum. Circular dichroism (CD) spectroscopy on bulk solid samples confirmed the presence of an excess population of one enantiomer (C2-symmetric atropisomer), most notably for compounds 1c, 1e, and 1f. CD spectra could be recorded for all compounds in solution, similarly reflecting an excess population of one atropisomer. The experimental spectra were confirmed by TD-DFT simulations at the CAM-B3LYP/def2-tzvp level of theory. We conclude that the present group of ligands are worthy of further investigation as chelating agents for metal ions with applications in chiral catalysis or biology. [ABSTRACT FROM AUTHOR]

Despite the concurrence of histidine and cysteine in the active sites of proteins associated with Zn2+, Cd2+ and Hg2+, coordination studies of these metal ions with chelating ligands containing a combination of aromatic amine and alkylthiolate (N Ax Sy−) donors have been rare. The potentially tetradentate ligand 2-[bis(2-pyridinylmethyl)amino]ethanethiol (LH) and chloride salts were used to prepare new complexes of Cd2+ and Hg2+ for comparison with the known Zn2+ complex. Solution NMR studies revealed concentration-dependent equilibria between aggregate forms of the new complexes in CD3CN. Trends in homonuclear and heteronuclear coupling provided additional insight regarding solution equilibria. ESI-MS from acetonitrile solutions supported differences in preferred aggregation states consistent with the solution NMR studies. [ABSTRACT FROM AUTHOR]

Motivated by the urgent need to find new agents for the treatment of leishmaniasis and fungal infections, six copper(II) coordination complexes containing well-known azole drugs with antifungal and antiparasitic properties, i.e., ketoconazole (KTZ), clotrimazole (CTZ), and fluconazole (FLZ), were synthesized. By reacting copper(II) complexes containing a bidentate planar ligand, either 1,10-phenanthroline (phen) or 1,10-phenanthroline-5,6-dione (dione), with azole drugs under mild conditions, we synthesized the set of compounds investigated in this work, i.e., [Cu(phen)(CTZ)2(NO3)](NO3)·4H2O (1), [Cu(phen)(KTZ)2(NO3)](NO3)·3H2O·C2H10O (2), [Cu(phen)(FLZ)(NO3)]2(NO3)2·5H2O (3), [Cu(dione)(CTZ)2(NO3)](NO3)·5H2O (4), [Cu(dione)(KTZ)2(NO3)](NO3)·5H2O (5), and [Cu(phen)(FLZ)(NO3)]2·(NO3)2·5H2O (6). Chemical composition and structural features of the copper(II) complexes were characterized in depth using multiple analytical and spectroscopic techniques, i.e., conductivity measurements, elemental analysis, infrared (FT-IR), UV-Visible (UV-Vis), and electron paramagnetic resonance (EPR) spectroscopies. Furthermore, the stability of these complexes was validated through spectrophotometric measurements of aqueous solutions. Antileishmanial and antifungal properties were analyzed in vitro. Our results pointed out a remarkable anti-leishmanial activity for some of the investigated systems and a promising anti-Sporothrix activity for the complex [Cu(phen)(KTZ)2(NO3)]NO3. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3D) framework with the general formula {[Cu(μ3-dmg)(im)2]·3H2O}n (1) was synthesized using an aliphatic dicarboxylic acid linker 2,2-dimethylglutarate (dmg2−) and nitrogen-containing imidazole ligand (im) under conventional methods. 1 was characterized by FT-IR spectroscopy, elemental analysis, single crystal and powder X-ray diffractions, and thermal analysis techniques. Additionally, the optical and topological properties of compound 1 were also investigated. The single crystal X-ray data exhibit that 1 is an interesting 3D framework and it has a I41/a space group, which originates from two imidazole ligands, one dmg and three lattice water molecules. Topologically, 1 displays a lvt-a topology with the point symbol of {4.8.10}. In addition, the catalytic activity of compound 1 was investigated in the CO2 conversion into cyclic carbonates. It was found that compound 1 was an active catalyst even at low catalyst loading under 0.1 MPa CO2 at 80 °C. The yields of 23–99% were obtained. Compound 1 can be recycled at least four times without significant compromise in the activity in the first three catalytic reactions. [ABSTRACT FROM AUTHOR]

In manganese(III) complexes with BPh4− as the counter anion, the ligand field strength and non-covalent interactions between cations and anions of the flexible Schiff-base ligands (R-sal-N-1,5,8,12)2− are tuned by modifying the different substituents at the 5-position or 3,5-positions on the phenyl rings of the salicylaldehyde, and the magneto-structural properties of complexes 5-I-BPh4 (1), 5-tBu-BPh4 (2), 5-OCH3-BPh4 (3), naphth-BPh4 (4) and 5-Br-3-OCH3-BPh4 (5) are investigated. Complex 1 undergoes an incomplete SCO with two different Mn(III) sites, while complexes 2 and 3 remain in the HS state throughout the entire temperature range, suggesting the absence of magnetic state conversion. Under the effect of solvent, complex 4 shows different magnetic properties. Upon solvent loss, 4 displays a more complete SCO with a T1/2 of 140 K. In contrast to the complexes described above, complex 5 possesses two substituents, namely 5-Br and 3-OCH3. As a result, it exhibits an abrupt SCO effect due to the significantly stronger intermolecular cooperativity. [ABSTRACT FROM AUTHOR]

The synthesis of 1 : 1 and 1 : 2 complexes of Zn(II) hexafluoroacetylacetonate with sterically crowded triphenodioxazines (TPDO) is described, and the compounds are characterized using single-crystal X-ray crystallography, NMR, and IR spectroscopy. The electronic absorption (λmax = 530–630 nm) and fluorescence emission (λ flmax = 585–660 nm) spectra of the complexes substantially (up to 100 nm) bathochromically shifted relative to the spectra of the TPDO ligands. In highly dilute solutions, the Zn(hfac)2-TPDO complexes partially dissociate and exist in equilibrium with the ligand to reveal unusual excitation-dependent behavior of their fluorescent spectra. [ABSTRACT FROM AUTHOR]

A series of new manganese complexes of general formula 32-Mn4Xn , displaying a highly-reproducible [Mn II2 Mn III2 ] cluster core formation, was observed when tetra-p-adamantylcalix[4]arene 3 was used in combination with N,N′-chelating auxiliary ligands, such as bipy (32-Mn4(bipy)2, bipy = 2,2′-bipyridyl) and phen (32-Mn4(phen)2, phen = 1,10-phenanthroline), as well as with DMF/H2O solvent molecules (32-Mn4(dmf)4, 32-Mn4(dmf)2(H2O)2), acting as O-donor coligands, in the crystalline phase. Single-crystal X-ray diffraction revealed that the involvement of auxiliary ligands in coordination with Mn-ions results in the distortion of their coordination sphere and leads to the controlled compression of the {Mn4}-cluster core of complexes. Moreover, the appearance of adamantyl groups at the upper rim of the macrocyclic backbone of 3 influences the crystalline self-assembly of obtained clusters, providing a preferable "side-to-head" orientation of the cluster molecules within the crystal, leading to the observation of relatively higher {Mn4}⋯{Mn4} distances than those revealed for the earlier reported calix[4]arene supported {Mn4} clusters. All 32-Mn4Xn clusters demonstrated ferromagnetic interactions between the metal atoms within the cluster core independent of the nature of the O-donor or N-donor auxiliary ligands. [ABSTRACT FROM AUTHOR]

Controlling the spatial selectivity of the coupling sites in two-molecule reactions is critical for stereoselective product synthesis. Herein, we report a novel strategy that uses basic ETS-10 zeolite-supported copper (Cu/ETS-10) as a catalyst for the highly selective synthesis of Z-3-methyleneisoindolin-1-ones in the absence of ligands. It was found that the rigidity of the zeolite skeleton was conducive to the high configurational selectivity of the product. The Cu/ETS-10 catalyst was easily recovered by simple filtration and could be reused five times without loss of its initial activity. [ABSTRACT FROM AUTHOR]

Two new copper(II) complexes have been obtained by the reaction of sterically crowded triphenodioxazine ligands with Cu(II) hexafluoroacetylacetonate. Compound 1 is a co-crystal of Cu(hfac)2 moieties and triphenodioxazine molecules within a quasi-one-dimensional crystal structure with only weak Cu⋯N short intermolecular interactions (Cu⋯N distances are equal to 2.69(1) and 2.75(1) Å). In contrast, complex 2 has a binuclear structure with two Cu(hfac)2 units bridged through triphenodioxazine ligand with the covalent Cu–N bond length of 2.335(2) Å. The magnetic AC susceptibility data show that in spite of the absence of zero-field splitting in the Cu(II) ion having the ground state with spin S = 1/2, both compounds demonstrate slow magnetic relaxation at the applied magnetic field. For a quasi-one-dimensional complex 1, the optimal field for observing slow magnetic relaxation is 400 Oe, while for the binuclear complex it is 2500 Oe. The observed temperature dependence of the relaxation time in 1 is well described by the combination of Raman and direct mechanisms of relaxation, while for complex 2 the inclusion of Raman mechanism and quantum tunneling of magnetization is required to describe the relaxation behavior. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations have been carried out to investigate two synthesized iridium(III) complexes with substituted Phbd (1-phenyl-2-(pyridin-2-yl)-1H-benzo[d]imidazole) and Crbd (9-(4-(2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl)phenyl)-9H-carbazole) as ancillary ligands. The aim of this paper is to study the effect of the substituent on the geometrical structures, electronic and second-order nonlinear optical (NLO) properties, and UV-vis absorption spectra. It is found that the first hyperpolarizabilities can be easily modulated by the introduction of Phbd and Crbd units. The complex with Phbd possesses larger first hyperpolarizability values compared to the complex with Crbd as an ancillary ligand. Significantly, the changes in the first hyperpolarizabilities can be qualitatively explained by means of the charge transfer pattern. It is anticipated that the theoretical investigation of these iridium(III) complexes will be helpful for designing high performance and versatile NLO materials. [ABSTRACT FROM AUTHOR]

Three new Co(II)-based coordination polymers, namely [Co(L)]n (1), [Co(H2L)1.5(1,10-phen)(H2O)2]n (2), and {[Co2(L)(dpa)(H2O)2]·(H4L)0.5}n (3) (H4L = 5,5′-(ethene-1,2-diyl)diisophthalic acid, 1,10-phen = 1,10-phenanthroline, dpa = (E)-1,2-di(pyridin-4-yl)diazene), were solvothermally synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, and magnetic studies. 1 and 3 display a 3D framework with (4,6)-connected CrB-type topology, and 2 displays a 1D chain built by the unprotonated H2L linker. The magnetic studies indicated that CPs 1–3 show the presence of weak antiferromagnetic interactions within the Co(II) units. [ABSTRACT FROM AUTHOR]

Traditional methods in synthesizing large-scale propargylamines have various limitations such as low reaction temperature, formation of byproducts and requirement of anhydrous reaction conditions. In recent times, a potent alternative for the synthesis of these crucial scaffolds has been identified as A3-coupling processes (aldehydes, amines, and alkynes), which are generally mediated by a suitable transition metal catalyst. For the further development of catalysts for A3-coupling reactions, we have designed and synthesized two new isomeric inverse triazolyl-pyridine ligands (2 and 3) and their Ag(I) complexes (4 and 5). Complexes 4 and 5 are fully characterized using different spectroscopic techniques including molecular structure determination using single crystal X-ray diffraction studies. The activity of both the complexes was tested on an A3-coupling reaction and it was found that both complexes are highly active. The superior reactivity of the newly synthesized complexes in comparison to the known catalysts can be attributed to the particular electronic properties and coordination of the inverse triazolyl-pyridine ligand. [ABSTRACT FROM AUTHOR]

This work aims to synthesize multifunctional materials with tunable emission properties. To pursue this, three isomeric ligands; 2-(1H-1,2,4-triazol-1-yl)pyridine (L1), 3-(1H-1,2,4-triazol-1-yl)pyridine (L2) and 4-(1H-1,2,4-triazol-1-yl)pyridine (L3) were reacted with CuI to afford three different coordination polymers, [Cu2(μ3-I)2(L1)2]nCP1, [Cu2(μ2-I)2(L2)2]nCP2 and [Cu(μ2-I)(L3)]nCP3, respectively. CP1 consists of a 1D chain comprising double-stranded Cu2I2 secondary building units (SBUs), where each copper is coordinated with the triazolyl nitrogen of the ligand on each side of the chain while the pyridine nitrogen remains pendant. Contrary to this, both pyridine and triazolyl nitrogens of L2 and L3 coordinate to Cu to give 1D and 2D CP2 and CP3, respectively. CP2 has a discrete Cu2I2 rhomboid SBU bridged by two L2 ligands, whereas CP3 has Cu–I single chains bridged by two L3 ligands to give a 2D sheet structure. All three coordination polymers are emissive at room temperature with the emission colour varying from green and yellow to orange with a λmax of 538, 575 and 600 nm, respectively for CP1 to CP3. CP1 and CP3 show luminescence thermochromism on lowering the temperature from 298 K to 77 K, changing hues from green to blue and orange to yellow, respectively. In addition to unique emission properties, these CPs exhibit semiconductor behaviour, with electrical conductivity in the range of 10−7 S cm−1. It is proposed that the presence of the Cu2I2 double-stranded chain provides a better and continuous overlap of copper and iodine orbitals, giving better conductivity to CP1 compared to CP2 and CP3. [ABSTRACT FROM AUTHOR]

Orthoplatinated complexes [Pt(C^C*)(acac)] (1R), in which C^C* is orthoplatinated 3-R-1-phenyl-1H-benzo[d]imidazol-2-ylidene and R = Me and Ph, reacted with 1′-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) under protonation of the acetylacetonate ligand (acac) to produce the corresponding phosphinocarboxylate bischelate complexes [Pt(C^C*)(dpf-κ2O,P)] (2R) as single isomers with trans-P,C(carbene) geometry. The compounds were fully characterized by elemental analysis, spectroscopic methods, single-crystal X-ray diffraction analysis, and cyclic voltammetry. In addition, DFT calculations were used to determine differences in energy and the bonding situation between 2R and the hypothetical geometric isomers 3R with a trans-P,C(phenyl) arrangement. The experimental and theoretical results are consistent with the antisymbiosis effect observed in complexes of soft metal ions, namely with weakening of Pt–C bonds by strongly trans-influencing ligands. [ABSTRACT FROM AUTHOR]

An equimolar reaction of 5-chlorosalicylaldehyde and 2-bromo-4-chloroaniline yielded the Schiff base (Z)-2-((2-bromo-4-chlorophenyl)imino)methyl)-4-chlorophenol) (HL), which was used for complexation to Co2+, Ni2+, Cu2+, and Zn2+ metal salts. Elemental and thermogravimetric analyses, conductivity measurements, powder X-ray diffraction, nuclear magnetic resonance (¹H and 13C), infrared, ultravioletvisible, energy dispersive X-ray-scanning electron and mass spectroscopies confirm the Schiff base structure and show mono-nuclear homoleptic complexes of the type ML2 for all metal salts used. The crystal structures of Ni2+ and Cu2+ complexes revealed a perfect square planar geometry around the metal ions, with the ligand acting as bidentate through oxygen and nitrogen atoms of the phenolic and azomethine groups, respectively. The antimicrobial potential of the compounds was evaluated on some selected pathogenic bacteria consisting of Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Klebsiella pneumonioe and Pseudomonas aeruginosa) strains using an in vitro assay. Antioxidant activity was evaluated using the DPPH assay. The complexes showed enhanced activity over the free Schiff base ligand in all the assays. Toxicity studies on WISH-ATCC-CCL-25, human epithelial amnion (normal liver cell lines), and MRC-5-ATCC-CCL-171 (normal human lung fibroblast cell lines) revealed that at lower concentrations, the complexes did not affect the cell lines. A computational study was deployed to investigate the electronic properties of the ligands and the complexes relating to their stability, reactivity, and biological potential. The computational data corroborated sufficiently with the experimental findings. Molecular docking studies demonstrated the compounds' mechanism of action and identified potential binding sites consistent with the in vitro assays. Hirshfeld surface analysis was also performed on selected compounds to reveal qualitative and quantitative intermolecular interactions within the topology crystal network of crystal structures. [ABSTRACT FROM AUTHOR]

Two new polyoxometalate (POM)-based metal–organic supramolecular architectures, [Cu(Hpypa)2(PMo12O40)(μ2-Cl)] 3H2O (1) and [Co(H2bpap)(γ-Mo8O28)0.5(H2O)2] H2O (2), were successfully synthesized by using two self-designed pyrimidine-amide organic ligands [N-(pyridin-3-ylmethyl)pyrimidine-4-carboxamide (pypa) and N,N′-bis(4-pyrimidinecarboxamido)-1,5-pentane (bpap)], as well as Keggin-type POM anions and octamolybdate anions under hydrothermal conditions. Complex 1 is a 1D supramolecular structure containing dinuclear [Cu2(Hpypa)4(PMo12O40)2(μ2-Cl)2] units. Complex 2 exhibits a 3D supramolecular framework consisting of 1D [Co(H2bpap)(H2O)2]n4n+ metal–organic chains and free [Mo8O28]8− anions. The supercapacitor performances of complexes 1 and 2 in a three-electrode system were investigated. When the current density is 1 A g−1, 1 and 2 exhibit specific capacitances of 555 and 675 F g−1, respectively. The symmetrical supercapacitor assembled with complex 2 as the electrode modifier exhibits an energy density of 13.4 W h kg−1 with a power density of 450 W kg−1. Capacitance retention remains at 96% after 6500 cycles. At the same time, the electrochemical sensors prepared with complexes 1 and 2 can be used for the determination of Cr(VI)/Fe(III) ions in aqueous solution with high sensitivity and low detection limit. [ABSTRACT FROM AUTHOR]

Reactions of the bicompartmental bis(phenolato) compound 6,6′-methylenebis(2-((bis(pyridin-2-ylmethyl)amino)methyl)-4-chlorophenol)hemihydrate (H2L ½H2O) with 3d metal(II) ions afforded novel fully structurally characterized bridged acetato dinuclear complexes [Mn2(HL)(μ1,2-OAc)2]PF6 (1) [Zn2(HL)(μ1,2-OAc)(H2O)0.75(MeOH)0.25](PF6)2·0.45(H2O) (5) and [Cd2(HL)(μ1,1,2-OAc)(OAc)(H2O)]PF6·H2O (6) as well as the polymeric bridged-azido tetranuclear catena-[Cu4(HL)2(μ1,1-N3)2(μ1,3-N3)2](NO3)2·5H2O (4). The complex [Cu4(HL)2(ClO4)3(H2O)5](ClO4)3·5H2O (2) was partially characterized. In addition, three more dinuclear complexes [Cu2(H2L)(NO3)2(H2O)2](NO3)2 (3), [Cu2(HL)(OAc)(CH3OH)](PF6)2 (7) and [Cu2(HL)(NCS)2]NO3·2H2O (8) were also isolated. All complexes were characterized by CHN elemental analysis, IR and UV-Vis spectroscopy, ESI-MS, conductivity measurements and X-ray single crystal crystallography for compounds 1, 4, 5 and 6, where the bis(phenolato) ligand displayed different deprotonation (H2L, HL− and L2−). The magnetic susceptibility measurements over the temperature range 2–300 K revealed very weak antiferromagnetic coupling in dimanganese(II) 1 (J = −1.64(1) cm−1) and almost negligible magnetic interaction in dicopper(II) 2 (J = 0(3) cm−1). In the azido catena-[Cu4(HL)2(μ1,1-N3)2(μ1,3-N3)2](NO3)2·5H2O (4) complex, the J value of −133(3) cm−1 was obtained upon moderate-to-strong antiferromagnetic coupling through the di-μ1,3-N3-bridged dicopper(II) unit with no magnetic interaction between the two copper(II) ions in the di-μ1,1-N3-bridged unit. [ABSTRACT FROM AUTHOR]

This paper reports three structurally characterised Ln(III) ternary complexes, [Ln(hfaa)3(Hind)n] {Ln = La (n = 3), Er and Yb (n = 2); hfaa = hexafluoroacetylacetone anion and Hind = indazole}, and their photophysical properties in the pure near infra-red (NIR) region. The hfaa and H-indazole were used as a sensitizer and antenna ligands, respectively, in the complexes. The single crystal XRD and solution NMR studies show that the La complex is nine-coordinate, while the Er and Yb complexes are octa-coordinated. The paramagnetic Er and Yb complexes show very fast longitudinal relaxation rates (ρ = 1/T1), which make them very useful for para-shift relaxation probes used in MRI. Upon UV excitation, erbium and ytterbium exhibit their characteristic luminescence in the pure NIR region (800–1600 nm). These could be very useful in various advanced applications ranging from optical communication to defence. The complexes showed the highest oscillator strength in dichloromethane followed by acetonitrile, and the oscillator strength was lowest in methanol since methanol molecules replaced the Hind ligands and provided a symmetrical ligand field around the Ln ions. The complexes in solid state showed stronger NIR photophysical properties compared to those in solution. [ABSTRACT FROM AUTHOR]

Three mixed-valence trinuclear cobalt(III)–cobalt(II)–cobalt(III) complexes, [CoII{(μ-L1)(μ-OAc)CoIII(OAc)}2]·2.67H2O (1), [CoII{(μ-L1)(μ-OOCPh)CoIII(DMSO)0.8(OOCPh)0.2}2](ClO4)1.6 (2) and [CoII{(μ-L2)(μ-OOCPh)CoIII(DMSO)0.75(OOCPh)0.25}2](ClO4)1.5 (3), have been synthesized using two tetradentate N2O2 donor 'reduced Schiff base' ligands, H2L1 {1,3-bis(2-hydroxybenzylamino)2,2-dimethylpropane} and H2L2 {2,2′-[1,1′-(propane-2,2-diyldiimino)diethylidene]diphenol}, and acetate or benzoate as anionic co-ligands. These complexes have been characterized by spectroscopic measurements and their solid state structures have been determined by single crystal X-ray diffraction analysis. The cobalt(III)–cobalt(II)–cobalt(III) skeletons of complexes 1 and 2 are linear, centrosymmetric; but in complex 3, it is non-centrosymmetric. Both the central cobalt(II) and terminal cobalt(III) atoms are hexa-coordinated in all three complexes. The structure directing role of several noncovalent interactions in the solid state of the complexes has been investigated focusing on the H-bonding interactions mediated by the co-crystallized water molecules in 1 and the perchlorate counterions in 2 and 3. Thermo-gravimetric analysis (TGA) provided a thermal driven pathway to observe the loss of lattice water molecules from complex 1. All the complexes show good electrical conductivity, which has been rationalized by band gap measurements. The band gap in the solid state was determined experimentally and also by DFT calculations and it confirms that each of the complexes behaves as a semiconductor. These complexes have been used to fabricate Schottky barrier diodes. [ABSTRACT FROM AUTHOR]

Single crystal X-ray structurally characterised Fe3+ complex, [Fe(III)–TNESAL], derived from a multi-dentate tripodal imine (N,N′,N′′-tris-(2-aminoethyl)amine-tris-(3-ethoxysalicylideneimine, H3TNESAL) selectively recognizes Mg2+ through the generation of green fluorescence (λem = 488 nm) in HEPES buffered aqueous DMF (DMF/H2O, 3/1, v/v, 10 M HEPES buffer, and pH 8.1). The findings of the spectroscopic investigations suggest a metal ion displacement-based sensing mechanism in which Mg2+ relocates Fe3+ from the [Fe(III)–TNESAL] complex. The values for the detection limit and binding constant for Mg2+ are 7.66 × 10−9 M and 1.56 × 105 M−1, respectively. The fluorescence lifetime of the [Mg(II)–TNESAL] complex is 4.99 ns. The TD-DFT studies endorse the experimental spectroscopic data. [ABSTRACT FROM AUTHOR]

The spinel LiMn2O4 cathode has received substantial attention from researchers owing to its high voltage plateau, eco-friendliness, and cost-effectiveness. Nevertheless, its practical application has been impeded by severe capacity attenuation due to the Jahn–Teller effect and spontaneous disproportionation reaction. To overcome these issues, this study synthesized a series of manganese-based metal–organic frameworks with varying structures using aromatic carboxylic acids that contain different numbers of carboxyl groups as organic frameworks. These frameworks were then used as precursors for synthesizing spinel LiMn2O4 cathode materials. This approach aims to enhance capacity, cycle stability, and rate performance by reducing the diffusion resistance of lithium ions, exposing the (111) plane, and increasing the Mn3+ content. The LMO-PMA sample exhibited remarkable cycling stability (91.4% after 1000 cycles at 10C) and superior capacity (140.2 mA h g−1 at 0.2C, 113.1 mA h g−1 at 10C). This approach can be extended to the synthesis of other cathode materials. [ABSTRACT FROM AUTHOR]

Two novel Mn(II) complexes with non-steroidal anti-inflammatory drugs, fenamic (Hfen = 2-(phenylamino)benzoic acid) and flufenamic acid (Hflu = N-(3-trifluoromethylphenyl)-2-aminobenzoic acid) and neocuproine (neo) as a supporting ligand were designed, synthesized and characterized. Their molecular structure was determined by the single-crystal X-ray diffraction method, which revealed that the complexes are isostructural and form analogous molecules [Mn(neo)(fen)2] and [Mn(neo)(flu)2]. Both complexes create an interesting structural motif resembling molecular tweezers, with an open cavity between the fenamato and flufenamato ligands, and exhibit moderate radical scavenging activity, with the fenamato complex being more active. The cytotoxic effects of the complexes were studied on three selected cell lines, including epithelial hTERT HME1 used as a healthy control, endometriotic 12Z and endometrial cancer SK-UT-1. The complexes were most active against the 12Z among the studied cell lines, while the flufenamato complex, which showed an IC50 value around 2 μM, was able to effectively trigger apoptosis through the caspase pathway. The impact of the complexes on the expression of selected genes in the tested cell lines was further investigated by qRT-PCR methods and their DNA binding properties towards the isolated genomic DNA samples were evaluated by competitive binding studies with ethidium bromide. Although some differences in the biological activity of the complexes were found, it can be concluded that both complexes target the inflammatory processes on a cellular level. [ABSTRACT FROM AUTHOR]

The biomolecular interactions of two previously reported cycloplatinated complexes, [Pt(C^N)(SMe2)(OCOCF3)] (C^N = deprotonated benzo[h]quinoline (bhq), 1, or deprotonated 2-phenylpyridine (ppy), 2), with bovine serum albumin (BSA) were investigated using various spectroscopic techniques. Structural characterization of 1 and 2 by NMR, UV-vis spectroscopies and conductivity measurements in aqueous media revealed that the TFAc functions as a leaving group ligand and is rapidly replaced by water molecules to form cationic cycloplatinated complexes having an aqua ligand, [Pt(C^N)(SMe2)(H2O)]+[CF3COO]−. Fluorescence titration of BSA indicated a strong binding interaction between Pt(II) compounds and protein with a static quenching mechanism. The thermodynamic parameters (ΔH°, ΔG° and ΔS°) showed that the binding was exothermic, involving main noncovalent hydrophobic forces and ionic interactions. As revealed by the displacement experiment, while 1 could bind to subdomain IIIA (site II) of albumin, the binding sites of 2 were mostly located at subdomain IIA (site I). The synchronous fluorescence spectra indicate that the cycloplatinated compounds induce structural changes in the protein structure. Moreover, far-UV CD spectroscopy is in agreement with a reduction of the α-helix content of albumin through binding. Further evidence for noncovalent association was obtained from inductively coupled plasma-optical emission spectroscopy (ICP-OES). In addition, the cytotoxicity investigation of 1 as a model complex against two human leukemic cancer cell lines (K562 and HL-60), MCF-7 (human breast adenocarcinoma), U-87MG (human glioblastoma cell line) and HT-29 (human colorectal adenocarcinoma cell line) suggested that 1 is more cytotoxic than cisplatin against HL-60 and generally toxic toward K562, MCF-7 and U-87MG. Finally, the quantitative structure–activity relationship (QSAR) was applied to correlate the structure of some cycloplatinated complexes including 1 and 2 with the SA albumin binding constant. [ABSTRACT FROM AUTHOR]

The reaction of [Ru(PPh3)3Cl2] with a group of four 1,4-diazabutadiene ligands (p-RC6H4N＝C(H)–C(H)＝NC6H4R-p; R = OCH3, CH3, H and Cl; abbreviated as L-R) in an equimolar ratio afforded chloro-bridged di-ruthenium complexes (1–4) of the general type [Ru2(PPh3)2(L-R)2Cl3]Cl. The crystal structures of complexes 1 (R = OCH3), 2 (R = CH3) and 4 (R = Cl) were determined and the molecular structure of complex 3 (R = H) was optimized using the DFT method. Each complex showed four intense absorptions in the visible and ultraviolet regions, the origin of which was probed employing TDDFT calculations. The complexes were found to serve as efficient catalyst precursors for the oxidative and deaminative C–N coupling of a series of primary amines, producing corresponding imines in good yields. Homo-coupling of benzylamines and cross-coupling of two differently substituted benzylamines or benzylamine with anilines and other aryl/alkyl amines could be realized using this catalytic protocol with aerial oxygen as the oxidant. [ABSTRACT FROM AUTHOR]

A new rigid bipyridinyl-derived ligand has been utilized for the fabrication of two metal–organic frameworks, denoted as [M(L)(mipa)]n [M = Zn (1) and Cd (2), L = 2,6-bis((E)-4-(pyridine-3-yl)benzylidene)cyclohexanone, H2mipa = 5-methylisophthelic acid], through solvothermal synthesis by using a mixed-ligand strategy. Structural analysis reveals that these isomorphic compounds display a 3,5-connected two-dimensional network with an unprecedented (42·67·8)(42·6) topology. Both of them exhibit certain chemical stability and thermal stability. Notably, the photocatalytic properties of the two compounds for the degradation of several organic dyes have been explored. [ABSTRACT FROM AUTHOR]

The design and construction of bifunctional molecular materials combined with spin crossover (SCO) and fluorescence have become a hot topic in magnetic materials research. However, achieving the synergistic effect between SCO and fluorescence in one system is complicated. Here, we designed two modified 2,6-bis(1-pyrazolyl)pyridine (bpp) ligands 4-(naphthalen-1-yl)-2,6-bis(1-pyrazolyl)pyridine (L1) and (E)-2,6-bis(1-pyrazolyl)-4-(2-(pyren-1-yl)vinyl)pyridine (L2), and synthesized two mononuclear FeII complexes [Fe(L1)2](ClO4)2 (1) and [Fe(L2)2](ClO4)2·2.63CH2Cl2 (2). The magnetic results showed that both 1 and 2 exhibit a complete SCO behavior, with 2 displaying a thermal hysteresis of about 7 K around 220 K. In addition, the transition temperature is 366 K for 1 and 215/222 K (T1/2↓/T1/2↑) for 2. Fluorescence measurements confirmed the synergistic effect between fluorescence and SCO in 1, featuring increased photoluminescence (PL) intensity during the spin-state crossing from low spin to high spin. However, 2 showed the coexistence of SCO and fluorescence without a synergistic effect. Complex 1 indicates that introducing fluorescent groups into SCO molecules provides a reasonable strategy for constructing magnetic and fluorescent bi-functional materials. [ABSTRACT FROM AUTHOR]

The reactions of Eu(III) and Tb(III) hexafluoroacetylacetonates (hfac−) with 2,4-bis(diphenylphosphino)pyrimidine dioxide (L1), 4,6-bis(diphenylphosphino)pyrimidine dioxide (L2), or 3,6-bis(diphenylphosphino)pyridazine dioxide (L3) afforded a new series of one-dimensional coordination polymers [LnL(hfac)3]n (L = L1, L2, and L3). Compounds [TbL2(hfac)3]n and [LnL3(hfac)3]n (Ln = Eu, Tb) consist of the eight-coordinated Ln(III) atoms linked by L2 and L3 ligands in the O,O′-bridging manner (an O8 polyhedron). In [LnL1(hfac)3]n (Ln = Eu, Tb) and [EuL2(hfac)3]n, one of the N atoms of bridging diphosphine dioxide is involved in the coordination to the Ln3+ ion resulting in a N1O8 polyhedron. All coordination polymers exhibit high thermal stability above 300 °C. The Eu(III) coordination polymers display strong photoluminescence with the solid-state quantum yield up to 61% observed for [EuL1(hfac)3]n. The chelating coordination of L1 and L2 increases considerably the energy transfer efficiency from the ligands to Eu(III) compared to that of L3. The centrosymmetric coordination polymers [LnL1(hfac)3]n exhibit strong triboluminescence that is clearly observed even in daylight at ambient temperature, while their non-centrosymmetric analogue [EuL2(hfac)3]n displays lower triboluminescent activity, which is visible only in the dark. [ABSTRACT FROM AUTHOR]

The detection of antibiotics is still the focus of global attention, because their abuse can lead to biological hazards. Herein, three new coordination polymers as fluorescent sensors, namely [Cd3(L1)(MTC)2(H2O)6] (CP 1), [Zn(L1)(HMTC)·2H2O] (CP 2) and [Cd3(L2)(MTC)2(H2O)6] (CP 3) [H3MTC = trimellitic acid, L1 = (E)-4,4′-(ethene-l,2-diyl)bis(N-pyridin-3-yl)benzamide) and L2 = (E)-4,4′-(diazene-1,2-diyl)bis(N-(pyridin-3-yl)benzamide)], were synthesized by using two bis(pyridyl)-bis(amide) ligands with different spacers and trimellitic acid mixed ligands under hydrothermal conditions, which were structurally characterized by single crystal X-ray diffraction, PXRD and IR. CP 1 and CP 3 have similar 2D coordination networks and 3D supramolecular structures, while CP 2 is a 2D coordination structure formed by alternatively linking 1D chains of Zn-L1 and Zn-HMTC, which is further extended to a 3D supramolecular framework. In addition, CPs 1–3 can highly efficiently detect two classes of antibiotics, chlortetracycline and furaltadone, with low LODs, excellent anti-interference ability, pH stability and recyclability. In CPs 1–3, CP 1 has the lowest LOD (5.12 × 10−8 M for CTC and 9.41 × 10−8 M for FTD). The sensing mechanisms, and the influences of composition and structure differences on the performances are discussed. The results provide a reasonable experimental reference for designing CPs and understanding the influencing factors of fluorescence performances. [ABSTRACT FROM AUTHOR]

A series of polynuclear Cu(II) complexes, namely, (Him)2[Cu2(pzdc)2(H2O)2] (1), [Cu3(pzdc)2(im)2(H2O)4] (2), {[Na4Cu4(pzdc)4(im)4(H2O)2]·16H2O}n (3), (Hamp)2[Cu2(pzdc)2(H2O)2] (4), (H2tmdp)2[Cu4(pzdc)4(H2O)2]·2H2O (5), {[Cu2(pzdc)2][Cu(H2O)6]}n (6), and [Cu3(pzdc)2(en)2(H2O)2]n (7), were successfully synthesized under the reaction of Cu(NO3)2·3H2O, pyrazole-3,5-dicarboxylic acid, and various ancillary ligands (im = imidazole, amp = 4-aminopyridine, tmdp = 4,4′-trimethylenedipyridine, and en= ethylenediamine). The magnetic study based on the secondary building Cu(II) unit with pyrazole-3,5-dicarboxylate bridges can be divided into three groups: (Group I) dinuclear Cu(II) units of 1, 4, and 6, (Group II) trinuclear Cu(II) units of 2 and 7, and (Group III) tetranuclear Cu(II) units of 3 and 5. The magnetic properties of 1 and 4 (group I) exhibit spin-canted antiferromagnetism while 6 exhibits typical antiferromagnetic coupling within the Cu(II) dimer with the paramagnetism from the [Cu(H2O)6]2+ unit. Group II exhibits antiferromagnetic interactions within the Cu(II) trimer for 2 and 7. Group III displays antiferromagnetic and weak ferromagnetic interactions within the tetranuclear Cu(II) unit. [ABSTRACT FROM AUTHOR]

Complexes of La (1), Sm (2), Gd (3), Er (4) and Yb (5) with benzophenanthroline-derivative ligands were synthesized under mild conditions through reactions of 8,10-di-tert-butylbenzo[b][1,10]phenanthrolin-11-ol (H(bphen)) with tris(trimethylsilyl)amide compounds of rare earth metals. The coordination arrangement of the ligand and complexes 2, 4 and 5 were established via single-crystal X-ray structural analyses. The La, Sm and Gd complexes in the solid state exhibited ligand emission of moderate intensity in the region from 600 to 850 nm. In the spectra of the Er and Yb complexes, there was no ligand emission, but f–f transition bands typical for the corresponding metal ions were observed. The complexes showed one reduction (E Red11/2 −2.04 V) and three oxidation events (E Ox11/2 at −0.05 to 0.01 V, E Ox21/2 at 0.22–0.26 V and E Ox31/2 at 0.41–0.44 V vs. Fc+/Fc) via cyclic voltammetry, corresponding to successive one-electron oxidation events of the phenolate moieties to phenoxyl radicals. [ABSTRACT FROM AUTHOR]

In this manuscript we report the preparation of four new zinc complexes, [{(μ-CH3COO)ZnL1}2Zn]·2DMSO (1), [{(DMF)ZnL1(μ-CH3COO)ZnL1Zn(N3)}]·0.64DMSO·0.36EtOH (2), [(μ-CH3COO)2Zn2L1]n(3) and [Zn2L2Cl2] (4), and their characterization by elemental and spectral analyses, where H2L1 is 1,3-propanediylbis(iminomethylene)bis(4-chlorophenol) and H2L2 is 1,3-propanediylbis(iminomethylene)bis(6-methoxyphenol). The structures have been confirmed by single crystal X-ray diffraction analysis. The synthetic strategy for complexes 1 and 2 involves the use of drops of DMSO, which is essential to stabilize the crystals of 1 and 2, respectively, indicating the importance of DMSO in the stabilization of the complexes. A thorough DFT calculation using the quantum theory of atoms-in-molecules and the non-covalent interaction plot (NCI plot) indicates the formation of strong H-bonds, CH⋯π and ancillary SpBs in complexes 1 and 2. DMSO has not been added during the synthesis of complexes 3 and 4, where no spodium bonds have been observed. Strong self-assembled (π–π stacked or H-bonded) dimers have been found in the solid state structures of 3 and 4. [ABSTRACT FROM AUTHOR]

The syntheses, characterizations, and catalytic activities of three zinc complexes and one lithium compound based on β-diketiminate ligands are described. The reactions of ZnEt2 with one equivalent of and two equivalents of ligand HL1, which bears a large 2,4,6-tricyclopentylphenyl substituent, afforded compounds [(L1)ZnEt] (1) and [(L1)2Zn] (2), respectively. The deprotonation of bis(β-diketiminato) ligand H2L2 by nBuLi generated complex [(L2)Li2(THF)2] (3). Compound 3 reacted with anhydrous zinc chloride in a stoichiometric ratio of 1 : 2 to produce [(HL2)Zn2Cl3]·Tol (4 Tol). In compound 4 Tol, only one β-diketimine unit was deprotonated, and the two zinc atoms were bridged by a chloride atom. The catalytic activities of 1–4 toward the borylation of aryl iodides with 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bis(1,3,2-dioxa-borolane) (B2Pin2) were studied. Compounds 1 and 4 were both active for this coupling reaction, and complex 4 displayed much higher activity than that of 1. The borylation reactions feature a wide substrate scope, high functional group versatility and mild conditions. Compound 3 was not catalytically active toward the borylation reaction, but it showed excellent catalytic performance in the hydroboration of aldehydes and ketones by pinacol borane (HBpin), leading to a series of boric esters with high yield. [ABSTRACT FROM AUTHOR]

In this work, cobalt complexes 1 and 2 were synthesized from ligands L1 (1,2-bis(2-phenyl-2-(pyridin-2-yl)hydrazineylidene)ethane) and L2 (1,2-bis(2-(pyridin-2-yl)hydrazineylidene)ethane) in moderate yields. These complexes were characterized by UV-visible, IR and ESI-MS spectroscopic studies. The molecular structure of complex 1 was determined by X-ray crystallography. Complexes 1 and 2 were employed as catalysts for the oxidation of sp3 C–H bonds. A total of 12 substrates were investigated for the oxidation of benzylic and aliphatic sp3 C–H bonds. A reaction pathway was proposed and possible reactive intermediate species was successfully characterized by ESI-MS spectroscopic studies. [ABSTRACT FROM AUTHOR]

New triazine ligands C3H5N5O (L1) and C5H5N5O3 (H2L2) were synthesised by reacting diaminoguanidine hydrochloride and glyoxylic acid in 1 : 1 and 1 : 2 molar ratios, respectively, at 150 °C in a green solvent (water). The corresponding cobalt complex, [Co3(L1)2(L2)4]·4H2O (1), was synthesised via a one-pot green synthesis process and was subsequently characterised by spectroscopic and elemental analysis methods. The structure of the cobalt complex was determined via single crystal X-ray diffraction analysis. Two types of ligands were observed in the cobalt complex: neutral (L1) and anionic (H2L2) ligands. The asymmetric unit was composed of one and a half crystallographically independent Co atoms, one L1 and two L22− ligands, and two lattice water molecules. Interestingly, the core structure of the complex had a neutral mixed-valence Co(III)–Co(II)–Co(III) trimer, and the overall neutrality of the complex was achieved because of the di-ionic nature of the H2L2 ligand. The spectral, thermal, and biological properties of the complex were explored, and biological aspects, such as antioxidant activity, protein binding and cytotoxicity, were examined. An assessment of the antioxidant activity of the compounds indicated better scavenging activity against ABTS˙+, DPPH˙, O2−, and NO˙ radicals than the known scavengers butylated hydroxyl anisole and ascorbic acid. The cobalt complex showed potential cytotoxicity toward MCF-7 cancer cells and was capable of inducing apoptosis. [ABSTRACT FROM AUTHOR]

Herein, a new Ru(II)-arene complex [(p-cymene)RuCl(bpyNO)]Cl, 1, bearing 5-methyl-[2,2′-bipyrimidine]-1-N-oxide (bpyNO, B) as a nitrogen donor ligand, has been prepared by reaction of [(p-cymene)RuCl(μ-Cl)]2, A, and bpyNO. The complex 1 was characterized by means of NMR spectroscopy, HR ESI-Mass, and X-ray crystallography techniques. The optical characteristics of these compounds in the ground state were investigated, and the findings were corroborated by calculations using density functional theory (DFT) and time-dependent DFT (TD-DFT). It was determined by a number of different approaches that every compound had suitable stability in biological media. On several different human cancer cell lines, including lung (A549), breast (MCF7), and cervical (HeLa) cells, and a normal cell line, lung fibroblasts (MRC5), the cytotoxic activities of A, B, 1, and another Ru(II) complex [(p-cymene)RuCl(bpy)]Cl, 2, bpy = 2,2′-bipyridine, were tested. Complex 1 demonstrated good to moderate anti-cancer activity. The effect of 1 on the proliferation of the non-tumorigenic cell line, MRC5, was more selective than that of cisplatin in distinguishing cancerous and non-cancerous cell lines. Furthermore, the most cytotoxic complex, 1, induces apoptosis, which causes cell death in the MCF-7 cancer cell line. Electrophoresis mobility shift assay and molecular docking were also performed in order to determine how and in which orientation these Ru(II) complexes are able to bind to DNA. [ABSTRACT FROM AUTHOR]

This study highlights the design, synthesis, spectroscopic characterization and catalytic phosphoesterase cleavage activity of two isostructural and isomorphous complexes, [Cu(L)]4 (1) and [Ni(L)]2·CH3OH (2) containing a new synthetic N,N-type donor ligand, namely 1,3-bis(((E)-(1H-pyrrol-2-yl)methylene)amino)propan-2-ol (H2L). The ligand, H2L has been synthesized by coupling of pyrrole-2-carboxaldehyde and 1,3-diamino-propane-2-ol under reflux. X-Ray crystallography study reveals that both the Cu(II) and Ni(II) centres in 1 and 2 adopt nearly a perfect square planar geometry and they display a high degree of similarity in their structural features. The biocatalytic fate of the complexes has been evaluated towards the hydrolytic cleavage of the phosphoester linkage in an aqueous DMF medium at room temperature. The spectrophotometric studies favour a higher turnover frequency for the hydrolysis of phosphoester bonds for the copper(II) complex (kcat, 1.56 × 104 h−1) over the nickel(II) complex (kcat, 5.61 × 103 h−1). Electrochemical, spectrophotometry, electron spray ionization mass spectrometry and detailed density functional theory studies illuminate the mechanistic interpretation attributing the crucial role of coordinated water, facilitating the nucleophilic attack on the phosphorous centre of pNPP, and shed light on mechanistic aspects for the efficient hydrolysis of phosphoester substrates for the copper complex over the nickel complex. [ABSTRACT FROM AUTHOR]

Photochromic molecules can transform from colorless closed to colored open forms by coordination with metal ions. Interaction of photochromic 1,3,3-trimethylindolino-β-naphthopyrylospiran (TMI-NPS) with manganese(II) hexafluoroacetylacetonate in o-dichlorobenzene results in the formation of deep red-violet solution indicating a coordination-induced transition from closed to colored open form. Precipitation of crystals yields {MnII(hfac)2·(μ2-TMI-NPS)}2 dimers (1) in which two Mn(II) atoms of hexafluoroacetylacetonate are bridged by oxygen atoms of two TMI-NPS ligands in the open form. Magnetic studies show a weak ferromagnetic exchange between MnII spins through oxygen atoms of TMI-NPS with estimated exchange interaction (J) of +1.07 cm−1. A positive Weiss temperature of +8 K also supports ferromagnetic coupling. As a result, MnII spins arrange parallel to each other at 2 K, and correspondingly, these dimers transfer to a high spin (S = 5) state. DFT calculations support noticeable mixing of the metal and ligand orbitals and essential positive charge on the TMI-NPS ligands, which can provide ferromagnetic exchange between MnII spins. [ABSTRACT FROM AUTHOR]

Novel Ir-based NHC complexes (1–4) were synthesised using N-alkenyl functionalised imidazolium salts with Ir(III) precursors. Complex 1 represents an unprecedented cyclometallated complex, which is the first and only example in literature, to our knowledge, of a non-aromatic C(sp2)–H activation leading to a C(sp3)–Ir cyclometallated product. A concomitant intramolecular/isomerisation process was followed by η3-allyl bond formation to a second Ir centre, thus forming a homonuclear bimetallic complex. Subsequent reactions with a range of imidazolium salts featuring different N-pendant arms were performed, including alkenyl and benzyl tethers. Selectivity with regards to cyclometallation behaviour of the iridium centre was observed in preference for a benzyl cyclometallated product over alkenyl cyclometallation. Benzyl-containing products proved most promising as active catalysts in both the hydrosilylation of internal alkynes with a conversion of up to 59% after 1 hour, as well as the transfer hydrogenation of ketone and aldehyde substrates with conversions of up to 100% after 18 hours using catalyst loadings of 4 and 1 mol% respectively. [ABSTRACT FROM AUTHOR]

New Pd(II) and Pt(II) complexes, [Pd(L)Cl] (1) and [Pt(L)Cl] (2), with an O,N,S donor azo-thioether pincer ligand (HL) are synthesized and thoroughly characterized by spectroscopic techniques. X-Ray structures of the complexes revealed the distorted square planar geometry around the central metal ions. Electronic structures and spectral properties are interpreted by DFT and TDDFT calculations. Interaction of the complexes with CT-DNA and BSA proteins is studied by absorption and fluorescence methods. Fluorescence titration revealed that the complexes strongly quench DNA bound ethidium bromide (EB) as well as the intrinsic fluorescence of BSA protein through static quenching. The high binding constants (Kb) obtained from the DNA binding studies promoted in vitro cytotoxicity assays of the complexes in various human cancer cell lines (colon cancer cell line HCT116, lung cancer cell line A549 and liver cancer cell line HepG2). The half maximal inhibitory concentrations (IC50) of complexes 1 and 2 are found to be less compared to cisplatin. [ABSTRACT FROM AUTHOR]

A series of new heteroleptic copper(I) complexes [Cu(N^N)(P^P)][BF4] (1–6), where N^N is a pyrazole-substituted 2,2′-bipyridine (5-(1H-pyrazol-4-yl)-2,2′-bipyridine (5-pzbpy, L1), 4,4′-di(1H-pyrazol-4-yl)-2,2′-bipyridine (4,4′-pz2bpy, L2), 5,5′-di(1H-pyrazol-4-yl)-2,2′-bipyridine (5,5′-pz2bpy, L3), and 3,8-di(1H-pyrazol-4-yl)-1,10-phenanthroline (3,8-pz2phen, L4)) and P^P is either oxybis(2,1-phenylene)bis(diphenylphosphane) (POP) or 1,3-bis(diphenylphosphanyl)propane (dppp), were successfully prepared and investigated. The crystal structures of 1, 2, 3 and 6 were determined by single X-ray diffraction. The novel copper(I) complexes 1, 2 and 3 show turn-on emission sensing for halogen ions. The fluorescence enhancement of the copper(I) complexes increases in the order of F− < I− < Br− < Cl−, and the differences in fluorescence intensity could be easily distinguished with the naked eye under UV light illumination. The 1H NMR titration indicated that the interaction involves hydrogen-bond formation between the halide (Cl−, Br− and I−) and the acidic H of the pyrazole group, with N–H deprotonation occurring at increasing F− concentrations. The result was further confirmed by carrying out theoretical calculations. [ABSTRACT FROM AUTHOR]

Two sets of maleonitrile-tethered, N-atom-donor tridentate ligands which are configurationally isomeric, 2-((E)-(aryl-methylene)amino)-3-((pyridin-2-ylmethyl)amino)maleonitrile (HL1-Ar) and 2-((aryl-methyl)amino)-3-((E)-(pyridin-2-ylmethylene)amino)maleonitrile (HL2-Ar) have been synthesized and fully characterized (where the aryl groups are 4-methoxyphenyl (HL1-OMe/HL2-OMe), 4-(trifluoromethyl)phenyl (HL1-CF3/HL2-CF3) and 2,4,6-trimethylphenyl (HL1-Mes/HL2-Mes)). The competitive role of the ligand's electronic effect and the type of metal ion were explored on the reactivity of Co(II) and Ni(II) metal ions with differently electronically tuned ligands. An Ni(II) metal ion was found to be effective towards the irreversible transformation of HL1-Ar to HL2-Ar (for all substitutions on the aryl group) where the simultaneous oxidation of amine and reduction of imine take place within a single conjugated maleonitrile-tethered ligand. Whereas, Co(II) interacted differently with each member of HL1-Ar. With the presence of an electron-donating group (EDG), a methyl group (at ortho and para positions) in the phenyl ring of HL1-Mes, Co(II) could selectively perform the ligand transformation. On the other hand, HL1-CF3 and HL1-OMe (with the presence of less EDG in the phenyl ring in comparison to HL1-Mes) did not respond to the amine–imine interconversion process. The isolated Co(II) and Ni(II) complexes were fully characterized using crystallography, cyclic voltammetry, NMR and UV-Vis spectroscopy and the correlation of spectral data changes with the different electronic environments of the ligands was well explained. The redox instability of Co(II) complexes with HL2-Ar towards aerobic oxidation was studied using spectro-electrochemical analysis. Finally, a mechanism for the amine–imine interconversion process was proposed based on experimentally identified intermediates as well as DFT calculations. [ABSTRACT FROM AUTHOR]