Search

[Display omitted] The covalent bonding of a ruthenium bipyridine complex derivative with the aromatic network of single walled carbon nanotubes (SWNT) through a stepwise protocol is presented, thus yielding the sample SWNT-Ru. To do that, an-amino decorated phenanthroline is bonded to the nanotube by means of the diazonium chemistry protocol, providing anchoring points for discrete organometallic units as depicted by the solid characterization techniques employed. The hybrid material, able to emit upon excitation, is active in the visible light-driven photocatalytic oxidation of organic sulfides to sulfoxides. SWNT-Ru presents a wide scope being able to convert more than 10 substrates with different characteristics, including added-value chemicals, with a stable performance over more than 6 cycles without metal leaching and enhanced activity compared to related homogeneous complexes. A versatile character is also demonstrated since this hybrid catalyst follows both possible photooxidation mechanisms. [ABSTRACT FROM AUTHOR]

Two molecular structures of a complex C26H16Cl2N2Pd (1) with a benzene hemisolvate (1•0.5C6H6) and a complex C34H20Cl2N2Pd (2) revealed similar conformations: one side of the arylethynyl group is flat to the bipyridine plane while the other side of the arylethynyl group is highly twisted to the plane because rhomb-like dimer fragments are formed between respective two complexes through CH⋯π interactions. The Hirshfeld surface analysis indicates that the most important contributions for the crystal packing of 1 are from H⋯H (33.6%), C⋯H/H⋯C (28.3%), Cl⋯H/H⋯Cl (17.8%), and C⋯C (10.6%) interactions and those of 2 are from H⋯H (36.5%), C⋯H/H⋯C (26.0%), Cl⋯H/H⋯Cl (15.7%), and C⋯C (12.3%) interactions, indicating the remarkable CH⋯π and electron distribution of molecules by Cl ions. The benzene solvate molecule of 1•0.5C6H6 performs to fill the internal space instead of the naphthyl group. Detailed crystallographic and DFT studies were performed to understand the molecular structures and the corresponding supramolecular associations. [ABSTRACT FROM AUTHOR]

Bipyridine and related compounds are starting materials or precursors for a variety of valuable substances such as biologically active molecules, ligands for catalysts, photosensitizers, viologens, and supramolecular architectures. Thus, it is important to classify their synthesis methods and understand their characteristics. Representative examples include methods using homo and heterocoupling of pyridine derivatives in the presence of a catalyst. Because bipyridine compounds strongly coordinate with metal centers, a decrease in catalytic activity and yield is often observed in the reaction system. To address this issue, this review provides insights into advances over the last ~30 years in bipyridine synthesis using metal complexes under both homogeneous and heterogeneous conditions. Moreover, strategies for bipyridine synthesis involving sulfur and phosphorous compounds are examined. These alternative pathways offer promising avenues for overcoming the challenges associated with traditional catalysis methods, providing a more comprehensive understanding of the synthesis landscape. [ABSTRACT FROM AUTHOR]

The supramolecular complex formation between donor (E)-bis(18-crown-6)azobenzene ((E)-1) and bis(ammoniopropyl) derivatives of bipyridine and dipyridylethylene acceptors (2, (E)-3) was studied in MeCN using steady-state absorption and fluorescence spectroscopy, fluorescence kinetics, and quantum-chemical (DFT, TDDFT, QDPT) calculations. The complexes are quite stable, but they undergo decomposition via substitution by alkali and alkaline-earth metal cations. The formation of 1:1 and 1:2 complexes between (E)-1 and alkali and alkaline-earth metal cations (Mn+) was confirmed. Spectral-kinetic parameters and stability constants were calculated. The determined stability constants are generally lower than those for bis(crown)stilbene complexes due to moderate electron-donor ability of azobenzene. The plot of fluorescence quantum yields of 1·(Mn+)2vs charge density of the metal cation shows two separate linear relations for unipositive and dipositive ions. The results of quantum-chemical calculations supported the conclusions derived from steady-state experiments. The most stable conformations of pseudocyclic complex (E)-1·2 and two metal complexes were found. The latter involve 4 or 6 molecules of acetonitrile per each complex: (E)-1·(Ca2+)2·(MeCN)4, (E)-1·(K+)2·(MeCN)6. Based upon quantum-chemical calculations of model species, the character of absorption bands of crowns and their complexes with actual energy conversion pathway are discussed. [ABSTRACT FROM AUTHOR]

The structural transformations of metal nanoclusters are typically quite complex processes involving the formation and breakage of several bonds, and thus are challenging to study. Herein, we report a case where two lacunary Keggin polyoxometallate templated silver single-pods [PW9O34@Ag51] (SD/Ag51b) fuse to a double-pod [(PW9O34)2@Ag72] by reacting with 4,4'-bipyridine (bipy) or 1,4-bis(4-pyridinylmethyl)piperazine (pi-bipy). Their crystal structures reveal the formation of a 2D 44-sql layer (SD/Ag72a) with bipy and a 3D pcu framework (SD/Ag72c) with pi-bipy. The PW9O349− retains its structure during the cluster fusion and cluster-based network formation. Although the two processes, stripping of an Ag-ligands interface followed by fusion, and polymerization, are difficult to envisage, electrospray ionization mass spectrometry provides enough evidences for such a proposal to be made. Through this example, we expect the structural transformation to become a powerful method for synthesizing silver nanoclusters and their infinite networks, and to evolve from trial-and-error to rational. Controlling the structural transformations of metal clusters is challenging. Here, the authors synthesize a silver nanocluster and study the structural changes that take place upon reaction with bipyridine derivatives. [ABSTRACT FROM AUTHOR]

In this work we show, using the example of a series of [Cu(Xantphos)(N^N)]+ complexes (N^N being substituted 5-phenyl-bipyridine) with different peripheral N^N ligands, that substituents distant from the main action zone can have a significant effect on the physicochemical properties of the system. By using the C≡C bond on the periphery of the coordination environment, three hybrid molecular systems with −Si(CH3)3, −Au(PR3), and −C2HN3(CH2)C10H7 fragments were produced. The Cu(I) complexes thus obtained demonstrate complicated emission behaviour, which was investigated by spectroscopic, electrochemical, and computational methods in order to understand the mechanism of energy transfer. It was found that the −Si(CH3)3 fragment connected to the peripheral C≡C bond changes luminescence to long-lived intra-ligand phosphorescence, in contrast to MLCT phosphorescence or TADF. The obtained results can be used for the design of new materials based on Cu(I) complexes with controlled optoelectronic properties on the molecular level, as well as for the production of hybrid systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Investigating new types of β-diketonate based europium complexes. • Incorporation of Eu complexes into PMMA films to comprehensively investigate their long-term photoluminescence stability. • Eu-films were subjected to light, indoor, and dark storage conditions for a duration of 720 h. • the FAC-based europium complexes demonstrated good stability under light, indoor, and dark conditions. • β-diketonate ligands structure impact directly on the photostability of the Eu-films. In this work, two β-diketonate ligands: dibenzoylmethane (DBM) and Hexafluoroacetone (hfac) have been selected to synthesize a series of β-diketonate europium complexes based on bipyridine and terpyridine derivatives. These complexes were then incorporated into PMMA films to comprehensively investigate their thermal and long-term photoluminescence stability. Comparatively, Eu(hfac) 3 L 1-5 demonstrated higher heat resistance than Eu(DBM) 3 L 1-5 , as indicated by their respective initial decomposition temperatures. Various aspects including absorbance, excitation, and emission were examined in solution, powder, and within the PMMA-doped films. Notably, the complexes exhibited a remarkable red emission peak at 613nm and a high photoluminescence quantum yield. To assess their stability, the films were subjected to light, indoor, and dark storage conditions for 720h, with photoluminescence measurements recorded at both 0h and 720h. The results revealed that the hfac-based europium complexes (Eu(hfac) 3 L 1-5) demonstrated good stability under light, indoor, and dark conditions compared to the DBM-based europium complexes (Eu(DBM) 3 L 1-5). This study highlights the direct impact of the β-diketonate ligand structure on the stability of such complexes in films, thus showcasing their potential for future applications in stable optoelectronic devices. [ABSTRACT FROM AUTHOR]

The Cu(II) ion locates in a distorted octahedral geometry, defined by one O atom (O2) form one 6-phenylpyridine-2-carboxylate ligand and one N atom (N1) from 2,2'-bipyridine ligand at the axial positions (O2-Cu1-N1, 173.37(6)°), one O atom (O2') and two N atoms (N2, N2') form 6-phenylpyridine-2-carboxylate ligand, and one N atom (N1') from the 2,2'-bipyridine ligand in the equatorial plane. 8 Liu, S.-Y., Tian, J.-J., Zhu, L.-J., Tian, H.-T., Yang, M., Huang, K.-L., Xu, W.-T. 13 Wang, L.-H., Wang, Z.-J., Ouyang, J., Tai, X.-S. [Extracted from the article]

Amino acid chirality plays an important role in conveying directionality and specificity to their supramolecular organization. However, the impact of enantiopure and racemic amino acids on the favorable packing and macroscopic properties of organic cocrystals with nonchiral coformers is poorly understood. Herein, we performed a systematic study of the effect of chirality on the macroscopic properties of acetylated alanine (AcA) single crystals and cocrystals with a nonchiral photo-sensitive bipyridine derivative (BPE). Cocrystallization with BPE produced a marked morphology transition that improved the supramolecular chirality, thermal stability and mechanical strength of AcA crystals. The distinct supramolecular packing modes were analyzed by X-ray crystallography. The highest rigidity was observed for BPE/ dl -AcA, while BPE/ d -AcA and BPE/ l -AcA crystals exhibited higher efficiency of photo-induced emission for fluorescent imprinting, as well as significantly higher piezoelectricity. This work provides a striking illustration that subtle differences in amino acid stereochemistry translate into tunable macroscopic properties of organic cocrystals for future applications in rigid solids, fluorescent imprinting, and energy harvesting. [ABSTRACT FROM AUTHOR]

Herein, the syntheses, solid-state molecular structures, and characterization of two types of one-dimensional FeIII coordination polymers showing thermally induced spin crossover are reported. The reaction of [Fe(acen)Cl] (acen2 = N,N0-ethylenebis(acetylacetonylideneaminate) with 3,30-bpy or 4,40-bpy (bpy = bipyridine) produced zigzag and linear one-dimensional chain complexes, [Fe(acen)(3,30-bpy)][BPh4] (1) or [NEt3H][Fe(acen)(4,40-bpy)][BPh4]2-0.5(4,40-bpy) (2), respectively, as confirmed by single crystal X-ray diffraction analysis. Variable-temperature single crystal X-ray diffraction measurements, continuous-wave X-band electron paramagnetic resonance (EPR) spectra, 57Fe Mössßauer spectra, and DC magnetic susceptibility data revealed that complex 1 exhibited a gradual and complete spin crossover at a transition temperature of 212 K, while complex 2 undergoes an incomplete spin crossover even at 400 K. [ABSTRACT FROM AUTHOR]

A new series of pyrazole, bipyridine, N-amide derivatives and Schiff bases was synthesized using compound 2-(3-cyano-6- (thiophen-2-yl)-4,4′- bipyridin-2-yloxy) acetohydrazide (3) as a starting material. The compounds structures were confirmed depending on the spectroscopic methods and elemental analysis. Also, the compounds were evaluated as anticancer agents by the compounds screened towards adenocarcinoma breast cancer cell line (MCF-7). The compounds showed a promising cytotoxic effect against human breast cancer cells. Compound 7c showed the most effective activity compared to other compounds with (IC50 = 0.6 ± 0.01 μg mL−1) in comparison with the reference drug doxorubicin (IC50 = 1.6 ± 0.02 μg mL−1). While compound 3 is closely active with doxorubicin. Also compounds 2, 4, 6, 7a, 7b and 7d showed noticeable cytotoxic effect. Early and late apoptotic cells were detected using Acridine orange/Ethidium bromide staining technique. The results of biologically screening of the tested compounds give an idea about the importance in the compounds acting against breast cancer and may lead to the discovery of a potent anticancer agent. [ABSTRACT FROM AUTHOR]

We report the study of a series of Ru-bipyridine (Ru-Bpy) complexes to correlate their photophysical and electrochemical properties to their performance in [4 + 2] cycloadditions, as a model reaction for electron transfer catalysis. Redox potentials, absorption and emission spectra, quantum yields and DFT calculations are presented to understand the catalytic transformation. The study shows that complex [Ru(Bpy) 3 ](PF 6 ) 2 is the more active photocatalyst, giving complete conversion to the product after 2 h reaction under white light. Any substitution in the para position of the Bpy ring decreases the reaction conversion. The [4 + 2] cycloaddition can be performed with different substrates and dienes, using either acetonitrile or nitromethane as solvents. Mechanistic studies suggest that the active catalyst for the transformation is [Ru(Bpy) 3 ] 3+ and that the rate determining step is the oxidation of [Ru(Bpy) 3 ] 2+ to generate the corresponding Ru 3+ species. [ABSTRACT FROM AUTHOR]

In the title compound, [(tBuSiMe2O)2MoO2(2,2'-bipyridine)] or [Mo(C6H15OSi)2O2(C10H8N2)], the MoVI atom has a distorted octahedral environment with the siloxy substituents occupying the trans positions. The complex contains a rare (R3SiO)2MO2 (M = Mo, W) structural motif and was formed in a reaction between sodium molybdate and tert-butyldimethylsilyl chloride in the presence of 2,2-bipyridine. In the crystal, neighbouring molecules are linked by C-H...==Mo hydrogen bonds, forming chains propagating along the a-axis direction. [ABSTRACT FROM AUTHOR]

Facile synthetic routes for three 4-substituted 2,2'-bipyridine derivatives, 4-[2-(4-methylphenyl)ethynyl]-2,2,-bipyridine, C19H14N2, (I), 4-[2-(pyridin-3-yl)ethynyl]-2,2'-bipyridine, C17H11N3, (II), and 4-(indol-4-yl)-2,2'-bipyridine, C18H13N3, (III), via Sonogashira and Suzuki-Miyaura cross-coupling reactions, respectively, are described. As indicated by X-ray analysis, the 2,2'-bipyridine core, the ethylene linkage and the substituents of (I) and (II) are almost planar [dihedral angles between the two ring systems: 8.98 (5) and 9.90 (6)° for the two molecules of (I) in the asymmetric unit and 2.66 (14)° for (II)], allowing π-conjugation. On the contrary, in (III), the indole substituent ring is rotated significantly out of the bipyridine plane [dihedral angle = 55.82 (3)°], due to steric hindrance. The crystal packings of (I) and (II) are dominated by π-π interactions, resulting in layers of molecules parallel to (302) in (I) and columns of molecules along the a axis in (II). The packing of (III) exhibits zigzag chains of molecules along the c axis interacting through N--H...N hydrogen bonds and π-π interactions. The contributions of unknown disordered solvent molecules to the diffraction intensities in (II) were removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9-18] algorithm of PLATON. The given chemical formula and other crystal data do not take into account these solvent molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ru(II)-picolinate photosensitizer bearing four phosphonate groups was synthesized. • Replacement of bipyridine with picolinate red-shifted the MLCT transition. • Rupic @Pt-TiO 2 showed higher activity than Rubpy @Pt-TiO 2 under red light irradiation. To utilize a wider region of the solar spectrum for solar-fuel production, we newly synthesized a heteroleptic Ru(II)-picolinate complex, [Ru(H 4 dpbpy) 2 (pic)]+ (Rupic ; H 4 dpbpy = H 4 dpbpy = 2,2′-bipyridine-4,4′-diphosphonic acid, Hpic = picolinic acid) as a red light-absorbing molecular photosensitizer. Rupic exhibited metal-to-ligand charge-transfer (MLCT) absorption and emission (λ abs and λ em = 491 and 711 nm, respectively) over a longer wavelength region than that observed with the bipyridine derivative [Ru(H 4 dpbpy) 2 (bpy)]2+ (Rubpy , bpy = 2,2′-bipyridine). The Ru(III)/Ru(II) redox potential of Rupic (E ox = +1.07 vs NHE) was approximately 0.27 V more negative than that of Rubpy , owing to the weaker ligand field strength of pic than that of bpy. Moreover, as expected, owing to the red-light absorption ability of Rupic, the photocatalytic H 2 evolution reaction activity of the Rupic -sensitized Pt-TiO 2 nanoparticles (apparent quantum yield, AQY ∼ 3 %) under red light illumination (λ = 625 ± 35 nm) was significantly higher than that of its Rubpy -sensitized analog (AQY ∼ 0.5 %). These results indicate the superior photosensitizing performance of the Ru(II)-picolinate complex for H 2 production under sunlight illumination. [ABSTRACT FROM AUTHOR]

[Display omitted] • Luminescence quenching of the excited 3MLCT by molecular oxygen. • Photosensitized generation of singlet oxygen by heteroleptic ruthenium (II) complexes. • Energy transfer versus charge transfer in the quenching process. • Effect of the partial charge transfer on the efficiency of singlet oxygen production. The photophysical properties of some synthesized heteroleptic polypyridyl ruthenium(II) complexes of the form [Ru(bpy) 2 L](PF 6) 2 where L = 2,2′-bipyridine, 4,4′-dimethoxy-2,2′-bipyridine, 1,10-phenanthroline, 4,4′-dimethyl-2,2′-bipyridine, 4,7-diphenyl-1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline, are investigated in acetonitrile. The excited state lifetime of the metal to ligand charge transfer (3MLCT) states of these complex ions are found to be ligand dependent and were found to be in the range 0.56 μs to 1.5 μs. Oxygen quenching of the excited states rate constants, k q , were found to be in the range 1.50–2.24 × 109 M−1s−1. Singlet oxygen quantum yield values, Φ Δ , are found to vary from 0.40 to 0.60 and the efficiency, f Δ T , with which excited singlet oxygen, O 2 (1Δ g), is thereby produced was found to be in the range 0.55–0.85. Treatment of the data with charge transfer and non-charge transfer pathways using Schmidt's model shows that partial charge transfer parameter was in the range of 0.18 to 0.58. It has also been found that f Δ T decreases and oxygen quenching rate constants, k q , increases as p CT increases. [ABSTRACT FROM AUTHOR]

Although a theoretically extensive number of hydrophobic eutectic mixtures suitable for solvent extraction are obtainable, to date reported mixtures rely on a limited number of chelating groups, namely phosphine oxide, carboxylic acid, and ketones. Herein, a new family of Type V Deep Eutectic Solvents (DES) based on the polypyridyl ligand 1,10-phenanthroline (phen) is presented with the aim of facilitating the extrapolation of the disclosed findings to other potential systems based on phen or bipyridine derivatives. The hydrophobic eutectic solvent composed of the natural phenolic extract thymol with phen exhibits a solid-liquid phase diagram with a useable liquidus compositional range on the thymol-rich side. The physical properties of the mixture are dependent on the presence of solutes liable to change the nature of the existing hydrogen-bonded network, most notably through the protonation of phen. The metal chelating ability of phen are retained when included as a DES component. Quantitative extraction of various transition metals cations (Cd(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) as well as the platinum group metal Pd(II) was obtained across a range of solvent compositions. The extraction of Li(I), Mn(II), Co(II) and Ni(II) was further studied as a function of the aqueous phase pH, with the extent of metal partition decreasing with the protonation of phen at pH values below 1.0. Building upon the luminescent properties of phen, the eutectic solvent was further applied as a simultaneous pre-concentration and quantification medium for Fe(II/III), allowing for the facile UV–vis detection of Fe up to 12 μg L−1. [Display omitted] • Characterisation of hydrophobic eutectic solvents based on 1,10-phenanthroline (phen) and natural phenolic compounds. • Excellent metal extraction capabilities for transition metals. • Protonation of phen under acidic conditions reduces metal partition and alters the properties of the eutectic solvent. • Pre-concentration and detection of Fe(II/III) to μg L−1 levels was achieved in the thymol+phen system. [ABSTRACT FROM AUTHOR]

Nowadays, the design and development of novel phosphorescent iridium(III) complexes for various optoelectronic applications is a well-recognized area of research. The fascinating photophysical properties of iridium(III) compounds are strongly influenced by the spin-orbit coupling exerted by the iridium(III) core, usually resulting in intense emissions with short excited-state lifetimes, which can be precisely controlled with the aid of molecular engineering of the chelating ligand. This review focuses on the recent developments and state of the art knowledge on phosphorescent iridium(III) compounds, especially on heteroleptic complexes derived from 2,3′-bipyridine class of cyclometalating and ancillary ligands, highlighting the excited state phenomenon behind their emission behavior. [ABSTRACT FROM AUTHOR]

We report the synthesis and properties of new ruthenium- p -cymene complexes [(η 6 - -cymene)Ru(L)Cl][Cl] prepared from tetracarboxylic acid ligands L = 3,3′,4,4′-tetracarboxylicacid-2,2′-bipyridine (3,3′,4,4′-H 4 tcbpy), their methyl and ethyl ester derivatives (R 4 tcbpy), 4,4′,5,5′-tetracarboxylicacid-2,2′-bipyridine (4,4′,5,5′-H 4 tcbpy), and 4,4′-di- n -nonyl bipyridine (4,4′-dnbpy). The complexes were fully characterized by NMR, IR, MS, elemental analysis, UV–vis spectroscopy, and cyclic voltammetry. The single-crystal structure of [(η 6 - p -cymene)Ru(4,4′,5,5′-H 4 tcbpy)Cl]Cl 2 shows a ‘piano stool’ geometry with Ru-C (2.177(2)-2.231(2) Å), Ru-N (2.0791–2.0801 Å) distances and an N-Ru-N bond angle (77.4°) similar to equivalents in the 4,4′-dicarboxylic acid sister complex. Compared to the latter and also the 4,4′-dnbpy derivative 3 , the UV–vis spectra show MLTC absorptions of the tetracarboxylates shifted to lower energy. The CVs show Ru(II/III) oxidation processes at 0.56–0.98 V ( vs Fc/Fc + ), depending on the ligand substitution. Changes in the electronic situation at the Ru centre reflected in the UV–vis and voltammetric data are correlated to HOMO levels calculated from photoelectron spectroscopy in air spectra recorded for all complexes. According to NMR experiments rapid ligand dissociation occurred when dissolving [(η 6 - p -cymene)Ru(3,3′,4,4′-Me 4 tcbpy)Cl]Cl 1b in DMF. In hot DMF decarboxylation led to the isolation of the 4′-dicarboxylic acid complex derivative. [ABSTRACT FROM AUTHOR]

Reaction of 6-methoxy-2,2′-bipyridine (bpy 6OMe ) with the electron-rich platinum(II) complex [Pt(Me) 2 (DMSO) 2 ] gave the rollover cyclometalated complex [Pt(κ 2 -N,C-bpy 6OMe -H) (Me) (DMSO)] under mild conditions. The occurrence of rollover cyclometalation was demonstrated by single crystal X-ray diffraction structure determination. In contrast, reaction of bpy 6OMe with [Pt(Ph) 2 (DMSO) 2 ] and [Pt(Cl) 2 (DMSO) 2 ] under mild conditions gave only adduct species of the type [Pt(X) 2 (bpy 6OMe )] (X = Ph, Cl). Under harsher conditions, activation of a C H bond in the methoxy substituent yielded the terdentate cyclometalated complex [Pt (κ 3 -N,N,C-bpy 6OMe -H)Cl]. Finally, reaction of Pd(II) and Au(III) derivatives invariably gave adduct species, with the exception of the dimeric complex [Pd(κ 2 -N,C-bpy 6OMe -H) (OAc)] 2 , which, however, was not isolated in pure form. The reactivity of bpy 6OMe , as emerged from this study, was compared with that of the corresponding disubstituted ligand 6,6′-dimethoxy-2,2′-bipyridine, previously studied by us. [ABSTRACT FROM AUTHOR]

The structure of the title salt, [CrCl(C10H8N2)2(H2O)][ZnCl4], has been determined from synchrotron data. The CrIII ion is coordinated by four N atoms from two 2,2'-bipyridine (bipy) ligands, one O atom from a water molecule and a chloride anion in a cis arrangement, displaying a distorted octahedral geometry. The tetrahedral [ZnCl4]2- anion is slightly distorted owing to its involvement in O-H···Cl hydrogen bonding with the coordinating water molecule. The Cr-N(bipy) bond lengths are in the range 2.0485 (13)-2.0632 (12) Å , while the Cr-Cl and Cr-OH2) bond lengths are 2.2732 (6) and 1.9876 (12) Å, respectively. In the crystal, molecules are stacked along the a axis. [ABSTRACT FROM AUTHOR]

With regard to crystal engineering, building block or modular assembly methodologies have shown great success in the design and construction of metal-organic coordination polymers. The critical factor for the construction of coordination polymers is the rational choice of the organic building blocks and the metal centre. The reaction of Zn(OAc)2·2H2O (OAc is acetate) with 3-nitrobenzoic acid (HNBA) and 4,4′-bipyridine (4,4′-bipy) under hydrothermal conditions produced a two-dimensional zinc(II) supramolecular architecture, catena-poly[[bis(3-nitrobenzoato-κ2 O, O′)zinc(II)]-μ-4,4′-bipyridine-κ2 N: N′], [Zn(C7H4NO4)2(C10H8N2)] n or [Zn(NBA)2(4,4′-bipy)] n, which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction analysis. The ZnII ions are connected by the 4,4′-bipy ligands to form a one-dimensional zigzag chain and the chains are decorated with anionic NBA ligands which interact further through aromatic π-π stacking interactions, expanding the structure into a threefold interpenetrated two-dimensional supramolecular architecture. The solid-state fluorescence analysis indicates a slight blue shift compared with pure 4,4′-bipyridine and HNBA. [ABSTRACT FROM AUTHOR]

The common feature of the title compounds, [Zn(C5H10NO2S2)2(C10H8N2)]-- 2H2O, (I), and [Zn(C6H12NOS2)2(C10H8N2)], (II), is the location of the Znn atoms on a twofold rotation axis. Further, each ZnII atom is chelated by two symmetry-equivalent and symmetrically coordinating dithiocarbamate ligands and a 2,20-bipyridine ligand. The resulting N2S4 coordination geometry is based on a highly distorted octahedron in each case. In the molecular packing of (I), supramolecular ladders mediated by O--H···O hydrogen bonding are found whereby the uprights are defined by {···HO(water)···HO(hydroxy)···}n chains parallel to the a axis and with the rungs defined by 'Zn[S2CN(CH2CH2)2]2'. The water molecules connect the ladders into a supramolecular layer parallel to the ab plane via water-O--H···S and pyridyl-C--H···O(water) interactions, with the connections between layers being of the type pyridyl-C--H···S. In (II), supramolecular layers parallel to the ab plane are sustained by hydroxy-O -- H···S hydrogen bonds with connections between layers being of the type pyridyl-C--H···S. [ABSTRACT FROM AUTHOR]

A new series of monosubstituted styryl- and bistyryl-2,2'-bipyridine luminophores (compounds 16-23) have been synthesized via Horner-Wadsworth-Emmons reaction involving a monophosphonate and donor aromatic aldehydes. In the title chromophores, the amino donors are varied between acyclic and cyclic while the alkoxy donors are varied in terms of their number and position. The absorption maxima of these chromophores shift predominantly due to intramolecular charge transfer (ICT) between different donor and acceptor moieties. The title donor-acceptor molecules exhibit intense fluorescence in solution at room temperature, and their emissive behavior has been found to be highly sensitive to solvent polarity. The fluorescence spectra and quantum yields of all the chromophores were recorded in four different solvent media, and the chromophores 16, 17, 19, and 21 exhibit fluorescence in the solid state too. The influence of the nature and position of the donor functionalities in the conjugated backbone of the bipyridine moiety on the electronic absorption properties of the title chromophores (16-23) has been demonstrated, which has further been corroborated by DFT and TD-DFT computation both in gas phase and in solution phase. The crystal structure of compound 18 has been described as a representative member of the family (16-23). [ABSTRACT FROM AUTHOR]

The synthesis of a series of N,N'-disubstituted acyclic (AL) and cyclic (CL) aza-bridged ligands incorporating 2,2-pipryidine subunits is described. 1H-NMR and IR spectral data support the proposed ligand structures. Dynamic 1H-NMR studies on diurea and diamide derivatives point to the presence of slowly interconverting conformers on the 1H-NMR time-scale, owing to N−H···N hydrogen bonding and/or a restricted rotation around the amide bonds. The ligands synthesized form 1:1 complexes with divalent transition metal ions. Upon complexation, bis-ester derivatives AL5 and CL5 undergo a metal-induced hydrolysis of the ester groups to carboxyl functions, which act as additional binding sites for the metal ion, as well as hydrogen-bonding donor-acceptor binding site to produce dimeric complexes.

Five new organometallic Ru(II) compounds (VI−X) with the general formula [Ru(η 6 -arene)( N , N )Cl]PF 6 , where arene- N , N correspond to methylisoeugenol-bipyridine (VI); anethole-bipyridine (VII); methylisoeugenol-ethylenediamine (VIII); anethole-ethylenediamine (IX) and methylisoeugenol-1,2-diaminobenzene (X), have been synthesized, fully characterized and biologically evaluated in vitro . The reaction conditions based on the reduction of [Ru(1,5-COD)Cl 2 ] n in situ with methyleugenol and estragole, which are natural ligands, induced an alkene isomerization on the allylic substituent of coordinated arenes. The Ru(II)-arene bond formation and isomerization of the C C bond on the allyl substituent was confirmed using 1 H NMR spectroscopy; this result was validated for compound VIII by X-ray diffraction. An XRD analysis revealed the presence of both enantiomers of the complex in the single-crystal. Compounds IX and X exhibited a better cytotoxic activity in vitro than carboplatin, which is a commercial drug, against three human tumor cell lines (MCF-7, PC-3 and HT-29). [ABSTRACT FROM AUTHOR]

A new bipyridyl derivative 1 bearing rhodamine B as visible fluorophore was designed, synthesized and characterized as a fluorescent and colorimetric sensor for metal ions. Interaction with Cu2+, Zn2+, Cd2+, Hg+, and Hg2+ ions was followed by UV/Vis and emission spectroscopy. Upon addition of these metal ions, different colorimetric and fluorescent responses were observed. 'Off-on-off' (Cu2+, Zn2+, and Hg2+) and 'off-on' (Hg+ and Cd2+) systems were obtained. Probe 1 was explored to mimic XOR and OR logic operations for the simultaneous detection of Hg+-Cu2+ and Hg+-Zn2+ pairs, respectively. DFT calculations were also performed to gain insight into the lowest-energy gas-phase conformation of free receptor 1 as well as the atomistic details of the coordination modes of the various metal ions. [ABSTRACT FROM AUTHOR]

C42H40Cl2MnN6O10S2, monoclinic, C2/c (no. 15), a=16.822(14) Å, b=11.552(9) Å, c=22.021(17) Å, β=91.920(13)°, V =4277(6) Å3, Z =4, Rgt(F)=0.0641, wRref(F2)=0.1654, T =296 K. [ABSTRACT FROM AUTHOR]

C21H21MnN2O7, triclinic, P..., a=8.6230(17) Å, b=9.967(2) Å, c=13.257(3) Å, α=80.92(3)°, β=78.53(3)°, γ=84.75(3)°, V=1100.5(4) ų, Z=2, Rgt(F)=0.0555, wRref(F²)=0.1474, T=293(2) K. [ABSTRACT FROM AUTHOR]

C27H18N6NiO7, monoclinic, P21/n (no. 14), a=8.0981(15) Å, b=21.660(3) Å, c=14.170(2) Å, β=95.215(4)°, V=2475.1(7) ų, Z=4, Rgt(F)=0.0418, wRref(F²)=0.0965, T=293 K. [ABSTRACT FROM AUTHOR]

C21H21MnN2O7, triclinic, P..., a=8.6230(17) Å, b=9.967(2) Å, c=13.257(3) Å, α=80.92(3)°, β=78.53(3)°, γ=84.75(3)°, V=1100.5(4) ų, Z=2, Rgt(F)=0.0555, wRref(F²)=0.1474, T=293(2) K. [ABSTRACT FROM AUTHOR]

C27H18N6NiO7, monoclinic, P21/n (no. 14), a=8.0981(15) Å, b=21.660(3) Å, c=14.170(2) Å, β=95.215(4)°, V=2475.1(7) ų, Z=4, Rgt(F)=0.0418, wRref(F²)=0.0965, T=293 K. [ABSTRACT FROM AUTHOR]

The compounds MoO2Cl2L (L = 2,2′-bipyridine (bipy) (1); 4,4′-di-tert-butyl-2,2′-bipyridine (di- t Bu-bipy) (2)), [MoO2Cl2(H2O)2]·(diglyme)2 (3), MoO2Cl2 (4), MoO2(CH3)2L (L = bipy (5); di- t Bu-bipy (6)), [MoO3(bipy)] n (7), {[MoO3(bipy)][MoO3(H2O)]} n (8), [Mo8O22(OH)4(di- t Bu-bipy)4] (9) and MoO3 (10) were tested as phosphoester bond hydrolysis promoters in aqueous media. Sodium para-nitrophenylphosphate (pNPP) was used as a model substrate for the phosphoester bond hydrolysis reaction, which was performed at 55 °C, using D2O as solvent and 100 or 10 mol% of the chosen promoter. The progression of all the reactions was monitored by 1H NMR spectroscopy. All studied systems promote phosphoester bond hydrolysis. The best performance was obtained with MoO2Cl2L compounds (1–4) and with the inorganic–organic hybrid {[MoO3(bipy)][MoO3(H2O)]} n (8). The studied compounds originate either homogeneous or solid/liquid biphasic systems. For the biphasic systems (1, 2, 5–9), the solid phase was recovered at the end of the reaction and characterized by FT-IR spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Thorocene [Th(Cot)2] (Cot=η8-C8H8) readily reacts with 2,2′-bipyridine to give [Th(Cot)2(κ2-bipy)], which has an unusual bent geometry. This compound is rapidly reduced by KC8 into the anionic derivative [(Th(Cot)2(κ2-bipy)]−. X-ray diffraction studies suggest the latter to be a Th(IV) compound with the bipyridyl radical anion. These complexes are rare examples of bent actinocene [An(Cot)2(L)] q− (q =0, 1; An=actinide) and bipyridine-containing thorium species. [Copyright &y& Elsevier]

Abstract: Coordination chemistry of 2,2′-bipyridine bearing an ortho-substituted phenyl group at the 6-position, i.e., 6-(o-X-phenyl)-2,2′-bipyridine (MeO-L: X = OMe; Me2N-L: X = NMe2) with [Ru(ttpy)Cl3] (ttpy = 4′-(4-tolyl)-2,2′;6′,2″-terpyridine) was investigated. The reaction of MeO-L and [Ru(ttpy)Cl3] in the presence of N-methylmorpholine afforded demethylated, O-coordinated complex [Ru(O-L)(ttpy)]+ (O-L: X = O) as well as the cyclometalated, C-coordinated complex [Ru(MeO-L)(ttpy)]+. On the other hand, reaction of Me2N-L and [Ru(ttpy)Cl3] in the presence of N-methylmorpholine afforded only N-coordinated complex [Ru(Me2N-L)(ttpy)]2+. The crystal structures, spectroscopic and redox properties were examined supplemented by DFT calculations. The spectroscopic and redox properties of RuN are more or less similar to those of [Ru(ttpy)Cl3]. On the other hand, the properties of RuC and RuO are mutually similar but significantly different from those of RuN. The anionic ligand in RuC and RuO raises the HOMO energy as compared to the neutral ligand in RuN, which is manifested in negatively shifted redox potentials, particularly the oxidation potentials, and thus, the red shift in the visible absorption band. Relevance of these complexes to sensitizers for dye-sensitized solar cells is briefly discussed. [Copyright &y& Elsevier]

[Display omitted] • Bipyridine was derivatized with polycyclic aromatic hydrocarbons. • Theoretical data indicated mixed local and intramolecular charge-transfer states. • Emission spectra of bipyridine derivatives showed dependence on solvent polarity. • Hybridized local and charge transfer states dominate in polar solvents. Photophysical studies of 4′-methyl-2,2′-bipyridine derivatized with the polycyclic aromatic hydrocarbons (PAHs) anthracene (mbpy-anth), naphthalene (mbpy-naph), and pyrene (mbpy-pyr) were acquired in different solvents. While the absorption spectra were not affected by the solvent nature, the emission ones showed red shifts with increase polarity consistent with an intramolecular charge-transfer (ICT) character. Theoretical calculations found a dominant "Hole" → "Particle" contribution for the first five transitions involving local excited-state (LE) and ICT transitions, with the latter being dominant at higher wavelengths (S 0 → 1CT). The fluorescence solvatochromic data suggested a hybridized local and charge transfer (HLCT) state for the mbpy-R compounds with the CT contribution prevailing in high polar solvents; a result that was corroborated by the monoexponential decay lifetimes. The Stokes shifts difference between heptane and dimethylsulphoxide, the most and least polar solvents used in this work, was calculated as 1315, 2969, and 808 cm−1 for mbpy-naph, mbpy-anth, and mbpy-pyr, respectively. The increase of the solvent polarity results in a red shift and a broadening of the emission and excitation bands for mbpy-anth and mbpy-naph with the spectra of the latter being the most affected. For mbpy-pyr, on the contrary, the emission spectra were narrower than the excitation ones indicating the L a transitions lie at lower energy than the L b. For this species, the results indicated an effective mixing of LE and CT states in the moderately polar solvents being in accordance with the observed single exponential decay which is likely related to one hybridized state. [ABSTRACT FROM AUTHOR]

The detection of bisphenol A (BPA) is very important for public health and environmental monitoring. In this work, BPA was found to be able to significantly quench the electrochemiluminescence (ECL) of the Ru(bpy)32+/2-(dibutylamino)ethanol (DBAE) system. Molecularly imprinted polymer was synthesized as solid-phase extraction sorbents, which were used for the selective extraction and purification of BPA. Under optimal conditions, the inhibited ECL intensity versus the logarithm of the concentration of BPA was in good linear relationship over a concentration range from 2.2 × 10−10 to 1.1 × 10−7 mol/L. The limit of detection was 4.5 × 10−11 mol/L ( S/ N = 3). The developed method was successfully applied for determination of BPA in river water with high sensitivity and reliability. Further, a possible mechanism for the quenching effects of the Ru(bpy)32+/DBAE system by BPA was also proposed. [ABSTRACT FROM AUTHOR]

Abstract: This work describes a highly controlled post-grafting of mono and dicationic 4,4′-bipyridine alkoxysilane derivatives (Bipy+ and Bipy2+) onto the surface of an ordered mesoporous silica, SBA-15. The materials obtained are designated as SBA-15/Bipy+Cl− and , both possessing chloride as counter ion. The regular arrangement of uniform pores of this inorganic matrix is likely to ensure good accessibility to the active centers (electron acceptors) attached to the surface. The materials are excellent adsorbents due to the ability of the functional groups to retain copper chlorides on their surfaces as anionic complexes ) in ethanol. From the adsorption, results it was possible to probe the functional surface monolayer of the materials, which present a highly homogenous distribution of functional groups inside the ordered SBA-15 channels, with an exchange efficiency of 93% for SBA-15/Bipy+Cl− and 94% for . Both adsorbent materials are potentially useful in the pre-concentration and further analysis of Cu(II) present in trace amounts in ethanol, extensively used as an automotive fuel in Brazil. [Copyright &y& Elsevier]

The ability to confine photoactive catalysts within metal–organicframework (MOF) materials affords the opportunity to expand the functionaldiversity of these materials into solar based applications. Here,the confinement of Ru(II)tris(2,2′-bipyridine) (RuBpy) by aMOF material derived from Zn(II) ions and trimesic acid (hereafter,USF2) is examined. Although the encapsulated RuBpy could not be crystallographicallyresolved within the MOF framework, the photophysical properties ofthe complex are characteristic of confinement including extended tripletmetal-to-ligand (3MLCT) lifetime (τethanol= 614 ns and τUSF2= 1.2 μs at 25 °C)and a slight hypsochromic shift in the steady-state emission spectrumrelative to RuBpy in ethanol. The extended lifetime is attributedto a deactivation of a nonradiative 3dd that is antibondingwith respect to the Ru(II)-bipyridine due to a confined molecularenvironment. These results represent one of the first examples ofRuBpy encapsulation and photophysical characterization within a polyhedralMOF material. [ABSTRACT FROM AUTHOR]

The complex: C19H18CdN2O5, Triclinic, P-1, a = 9.6654(11) Å, b = 10.5458(12) Å, c = 10.7081(12) Å, α = 108.5220(10)°, β = 92.0640(10)°, γ = 111.4760(10)°, V = 948.62(19) Å3, Rgt (F) = 0.0200, wRref (F2 ) = 0.0535, Z = 2, T = 293(2) K. [ABSTRACT FROM AUTHOR]

C28H30F4N2O8Ni, Monoclinic, P21/ n, a = 10.164(7) Å, b = 13.927(9) Å, c = 11.409(8) Å, β = 111.863(10) V = 1498.9(18) Å3, Z = 2, Rgt (F) = 0.0389, wRref (F2 ) = 0.0957, T = 296(2) K. [ABSTRACT FROM AUTHOR]

C25H23N5O4, triclinic, P1̅ (no. 2), a = 8.157(2) Å, b = 9.262(2) Å, c = 15.465(4) Å, α = 87.887(4)°, β = 89.803(4)°, γ = 72.727(4)°, V = 1114.9(5) Å3, Z = 2, Rgt (F) = 0.0755, wRret (F2 ) = 0.184, T = 298 K. [ABSTRACT FROM AUTHOR]

C40H40N4O12Ni, triclinic, P1̅, a = 7.6612(6) Å, b = 8.0725(7) Å, c = 16.3021(10) Å, α = 89.394(6)°, β = 77.966(6)°, γ = 69.868(8)°, V = 923.75(12) Å3, Z = 1, Rgt (F) = 0.0492, wRref (F2 ) = 0.1309, T = 293(2) K. [ABSTRACT FROM AUTHOR]

C16H10N2O4S1Cd, orthorhombic, P2(1)2(1)2(1), a = 8.977(2) Å, b = 11.751(3) Å, c = 14.224(4) Å, α = 90°, β = 90°, γ = 90°, V = 1500.6(6) Å3, Z = 4, Rgt (F) = 0.0188, wRref (F2 ) = 0.0431, T = 296(2) K. [ABSTRACT FROM AUTHOR]

C24H15N4O9Sm, monoclinic, P21/n, a = 6.780(2) Å, b = 27.939(8) Å, c = 11.546(4) Å, β = 101.630(4)°, V = 2142.1(12) Å3, Z = 4, Rgt (F) = 0.0221, wRref (F2 ) = 0.0587, T = 296(2) K. [ABSTRACT FROM AUTHOR]

C25H23N5O4, triclinic, P1̅ (no. 2), a = 8.157(2) Å, b = 9.262(2) Å, c = 15.465(4) Å, α = 87.887(4)°, β = 89.803(4)°, γ = 72.727(4)°, V = 1114.9(5) Å3, Z = 2, Rgt (F) = 0.0755, wRret (F2 ) = 0.184, T = 298 K. [ABSTRACT FROM AUTHOR]

A europium(III) hybrid material Eu(tta)3bpdc-SiO2@mTiO2 (Htta = 2-thenoyltrifluoroacetone, H2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid) was successfully designed and synthesized by the covalent grafting complex Eu(tta)3bpdc to SiO2@mTiO2 core–shell nanosphere. The FT-IR, PXRD, XPS, TEM, HRTEM, SAED, TGA and PL were performed to characterize these materials. The results indicate that core–shell nanosphere structure and anatase crystallites of SiO2@mTiO2 are retained well after grafting the europium complex. Hybrid material Eu(tta)3bpdc-SiO2@mTiO2 displays uniform nanosphere structure, bright red color and long lifetime, which can serve as a multicolor emission material modulated by using Al3+ ions via the cation exchange approach under a single-wavelength excitation. To the best of our knowledge, this work is the first multicolor emissive sensor for Al3+ ions based on the lanthanide hybrid material. [ABSTRACT FROM AUTHOR]

Primary tumor targeting is the dominant approach in drug development, while metastasis is the leading cause of cancer death. Therefore, in addition to the cytotoxic activity of a series of Ru(II) polypyridyl complexes of the type [Ru(dip)2L]2+ (dip: 4,7-diphenyl-1,10-phenanthroline while L = dip; bpy: 2,2′-bipyridine; bpy-SC: bipyridine derivative bearing a semicarbazone 2-formylopyridine moiety; dpq, dpq(CH3)2, dpb: quinoxaline derivatives) their ability to inhibit cell detachment was investigated. In vitro studies performed on lung cancer A549 cells showed that they accumulate in cells very well and exhibit moderate cytotoxicity with IC50 ranging from 4 to 13 µM. Three of the studied compounds that have dip, bpy-SC, or dpb ligands after treatment of the cells with a non-toxic dose (<1/2IC50) enhanced their adhesion properties demonstrated by lower detachment in the trypsin resistance assay. The same complexes inhibited both MMP-2 and MMP-9 enzyme activities with IC50 ranging from 2 to 12 µM; however, the MMP-9 inhibition was stronger. More detailed studies for [Ru(dip)2(bpy-SC)]2+, which induced the greatest increase in cell adhesion, revealed that it is predominately accumulated in the cytoskeletal fraction of A549 cells. Moreover, cells treated with this compound showed the localization of MMP-9 to a greater extent also in the cytoskeleton. Taken together, our results indicate the possibility of a reduction of metastatic cells escaping from the primary lesion to the surrounding tissue by prevention of their detachment and by influencing the activity of MMP-2 and MMP-9. [ABSTRACT FROM AUTHOR]