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Three low-dimensional Cu(ii)-based organophosphonates were synthesized: two molecular cationic complexes, [Cu2(μ2-L)2(2,2′BPy)2(H2O)2](NO3)2·S (1) and [Cu(L)(2,2′BPy)2]·NO3·(H2O)2 (3), and one neutral complex, [Cu2(μ2-L)2(2,2′BPy)2(NO3)2]·MeOH (2), assembled by the phosphonomonoester i.e., ethylhydrogen(anthracen-9-ylmethyl)phosphonate and an auxillary bidendate ligand (2,2′-bipyridine). Single-crystal X-ray diffraction analysis showed that complex 1 consisted of a dimer unit arranged supramolecularly with a nitrate anion and that these layers were further assembled viaπ…π interactions, which resulted in the formation of a porous supramolecular architecture. The cationic complexes 1 and 3 showed supramolecular templated assembly by simply altering the solvent, which resulted in a change in architecture. The remarkable change from a cationic complex to a neutral complex via the formation of an amorphous solid (1a) (a crystal–amorphous–crystal transformation) was observed when crystals of 1 were heated at 90 °C under vacuum. It is hypothesized that the uncoordinated nitrate ion moved from the lattice to the metal, resulting in the transformation of the cationic metal complex into a neutral metal complex. These complexes also showed luminescent behaviour. [ABSTRACT FROM AUTHOR]

A series of new RuII complexes has been synthesised, with different azo ligands as additional chromophore. The dyes are all intensely colored due to MLCT and ILCT transitions in the visible region. The photophysical study of the dyes, carried out by UV/Vis absorption and emission spectroscopy, showed unusual features such as intense solvatochromism and solvent-dependent extinction coefficients. The energies of these excited states have been tuned by changing the electron density across the series of azo ligands, and this results in different contributions from each charge transfer process for the different complexes and consequently, different emission behavior. The detailed behaviour of these dyes was further studied and interpreted through electrochemical, structural and computational techniques. The dyes do not work well as sensitisers for DSSCs and this is investigated by emission spectroscopy on TiO2 and ZrO2 films, suggesting poor charge injection to TiO2. [ABSTRACT FROM AUTHOR]

The interaction of MnCl2with the non-steroidal anti-inflammatory drug sodium diclofenac in the presence of 2,2′-bipyridine and pyridine resulted in the formation of cationic and neutral mononuclear complexes [Mn(diclofenac)(2,2′-bipyridine)(H2O)2] (diclofenac) (1) and [Mn(diclofenac)2(pyridine)2(H2O)2] (2), respectively. The structure of1was characterized by X-ray crystallography. In a preliminary attempt to evaluate the biological properties and possible application, the interaction of the complexes with calf-thymus DNA and human or bovine serum albumins was monitored. Additionally, the ability of the compounds to scavenge radicals such as 1,1-diphenyl-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and hydroxyl radicals was evaluated; the complexes were more potent scavengers than free sodium diclofenac. [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]

[Ni(5,5′-dmbipy)Cl]·3HO ( 1) complex was obtained from the reaction of NiCl·6HO with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) in a mixture of CHOH/CHCN. This complex was characterized by elemental analysis, IR, UV-Vis and luminescence spectroscopy, and its structure was determined by the single-crystal diffraction method. The Ni atom has a distorted octahedral coordination by four N atoms from two 5,5′-dmbipy ligands and two Cl anions. [ABSTRACT FROM AUTHOR]

Two 4-substituted 2,2'-bipyridines, namely 4-(ferrocenylethynyl)-2,2'-bipyridine ( I) and 4-ferrocenyl-2,2'-bipyridine ( II) have been synthesized and fully characterized via single-crystal X-ray diffraction and H and C NMR analyses. The π-conjugated system designed from 2,2'-bipyridine modified with the ferrocenylethynyl and ferrocenyl groups shows the desired planarity. In the crystal packing of I and II, the molecules arrange themselves in head-to-tail and head-to-head motifs, respectively, resulting in consecutive layers of ferrocene and pyridine moieties. [ABSTRACT FROM AUTHOR]

Chiral 2D and 3D metal-organic coordination polymers [Cu(bpy)(Hdml)(HCOO)]-(HCOO)·2HO ( 1) and [Cu(bpy)(Hphl)(HCOO)]·HO ( 2) were synthesized by heating a solution of copper( ii) salts, 4,4´-bipyridine (bpy), and α-hydroxycarboxylic acids, viz., S-3,3-dimethyllactic (Hdml) or S-3-phenyllactic (Hphl) acid, in a water- N, N´-dimethylformamide mixture. The structures of compounds 1 and 2 were determined by single-crystal X-ray diffraction. Compound 2 was characterized by X-ray powder diffraction, IR spectroscopy, thermogravimetric analysis, and elemental analysis. [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.

A new tetrapyridine ligand, 5,5′-(3-pyridyl)-2,2′-bipyridine (2) was prepared from 5,5′-dibromo-2,2′-bipyridine (1) via Pd(0)-mediated Suzuki coupling. The reaction was performed either directly upon the free ligand, or upon its Ru(II) complex. The structures of [Ru(1)3](PF6)2and [Ru(2)3](PF6)2were studied in solution by NMR, and in the solid state by single crystal X-ray diffraction. Solution NMR data suggests distorted structures, consistent with the observed slow reactivity of the ligands towards Ru(II) ions, and their reluctance to coordinate to Fe(II) ions. However, solid-state X-ray data indicated little distortion from ideal geometries, suggesting the effect may be more electronic than steric in nature. [ABSTRACT FROM AUTHOR]

Four new compounds prepared from the ligand 2,3-dipyridyl ketone oxime (L23) with varying Cu(II) salts were synthesised and structurally characterised, {[Cu(L23)(L23-H)](ClO4)}∞(1), {[Cu(L23)(L23-H)](BF4)¼(H2O)}∞(2), [Cu3(L23-H)2(L23′)(NO3)2OH]2(NO3)2(C3H8O)6(3) and [Cu(L23)Cl2]∞(4). The effects of differing counterions, as well as the rotational conformational versatility ofL23, were demonstrated by the differing polymeric structures that were observed. Complex1and2both existed as 1-D polymeric chains withL23acting as a pseudo-tetradentate ligand through an oxime–oximato bridge. Complex1formed a helical arrangement while2formed a chiral chain with both1and2exhibiting similar chiral packing. Complex3formed an unusual inverse–9–metallacrown–3 complex, with one of theL23ligands in a zwitterionic form. Complex4was present as a simple 1-D meso-helical chain. [ABSTRACT FROM AUTHOR]

Electrochemical properties of the [NiBr(bpy)] complex, where bpy = 2,2′-bipyridyl, have been studied in the presence of derivatives of ortho-phosphine phenol: 2-diphenyl phosphanyl-4-methyl phenol CHCH(PPh)OH ( 1), 2-diphenyl phosphanyl-4-methylphenyldiphenyl phosphinate CHCH(PPh)OP(O)Ph ( 2), and 2-diphenylphosphoryl-4-methyl phenol CHCH(P(O)Ph)OH ( 3). It is found that interaction of products of electrochemical reduction of complex [NiBr(bpy)] with 1 and 2 results in formation of active catalysts of the process of homogeneous oligomerization/polymerization of ethylene. [ABSTRACT FROM AUTHOR]

A series of platinum(ii) biphenyl 2,2′-bipyridine complexes containing electron-donating and electron-withdrawing moieties on the 4 and 4′ positions of the bipyridine ligand exhibit emission from excited states in the 600 nm region of the spectrum upon excitation in the metal-to-ligand charge transfer transition located near 450 nm. These complexes are distorted from planarity based on both single crystal structure determinations and density functional theory (DFT) calculations of isolated molecules in acetonitrile. The DFT also reveals the geometry of the lowest-lying triplet state (LLTS) of each complex that is important for emission behavior. The LLTS are assigned based on the electron spin density distributions and correlated with the singlet excited states to understand the mechanism of electronic excitation and relaxation. Time-dependent DFT calculations are performed to compute the singlet excited state energies of these complexes so as to help interpret their UV-Vis absorption spectra. Computational and experimental results, including absorption and emission energy maxima, electrochemical reduction potentials, LLTS, singlet excited states, and LUMO and HOMO energies, exhibit linear correlations with the Hammett constants for para-substituents σp. These correlations are employed to screen complexes that have not yet been synthesized. The correlation analysis indicates that the electronic structure and the HOMO–LUMO energy gap in Pt(ii) complexes can be effectively controlled using electron-donating and electron-withdrawing moieties covalently bonded to the ligands. The information presented in this paper provides a better understanding of the fundamental electronic and thermodynamic behavior of these complexes and could be used to design systems with specific applications. [ABSTRACT FROM AUTHOR]

The synthesis of 4,4′-dibenzodifuran-2,2′-bipyridine derivatives as ligands of organic ruthenium dyes for DSSC applications is described. Two new heteroleptic ruthenium complexes have been prepared and compared with commercially available N719 and Z907 dyes, using dip dyeing and flow dyeing methods in large area testing cells prepared for industrial purposes. The newly synthesized dyes revealed higher solar-to-electric energy conversion efficiency ( η ), measured at the AM1.5G conditions, up to 21% compared to N719 and up to 46% compared to Z907 , and external quantum efficiency of 53%. These results can be explained by enhanced light-harvesting of the benzodifuran moiety of the dyes that is related to photocurrent. [ABSTRACT FROM AUTHOR]

The 4-toluenesulfonyl-L-serine ligand (1), (tsserH2), was prepared from the reaction of L-serine and 4-toluenesulfonyl chloride in sodium hydroxide solution 1 M. The complexes [Pd(4,4′-dmbipy)(tsser)] (2) and [Pd(5,5′-dmbipy)(tsser)].0.5CH3CN (3) (4,4′-dmbipy is 4,4′-dimethyl-2,2′-bipyridine and 5,5′-dmbipy is 5,5′-dimethyl-2,2′-bipyridine) were also prepared from the reaction of PdCl2and 2,2′-bipyridine derivatives with 4-toluenesulfonyl-L-serine ligand in mixture of CH3CN/CH3OH (3:1) and in presence of sodium hydroxide solution 0.5 M. These compounds were characterized by elemental analysis, IR,1H NMR, and UV–Vis spectroscopy and their structures were studied by single-crystal X-ray diffraction method. The X-ray structure determinations show that in the both complexes, the PdIIatoms are four-coordinated in a distorted square-planar configuration by two N atoms from a bidentate bipyridine ligand and one N atom and one O atom from a bidentate tsser2-ligand. [ABSTRACT FROM AUTHOR]

Six novel coordination polymers {Co(HCOO)(4,4′-bipy)} ( 1), {[Ni(4,4′-bipy)(OH)(HO)]·suc·2HO} ( 2), {Ni(HCOO)(4,4′-bipy)} ( 3), {Zn(HCOO)(4,4′-bipy)} ( 4), {Cu(HCOO)(4,4′-bipy)} ( 5) and {[Cu(ox)(2,2′-bipy)]·2HO} ( 6) (suc succinic acid, ox oxalic cid) based on pyridine derivatives and carboxylates as ligands were designed and synthesized. The coordination polymers were characterized by elemental analysis, IR and UV-Vis spectra, powder X-ray diffraction, the thermo gravimetric analyses and single-crystal diffraction analysis. The structure analysis showed that the central metal atoms in coordination polymers 1, 2, 3, 4 and 6 all were six-coordination modes, forming distorted octahedron geometries. Cu atom in the coordination polymer 5 was four-coordination mode, forming square planar coordination geometry. While in the coordination polymers 1, 3 and 4, two metal centers were connected by bridging coordination fashions of formic acid ligand, forming a three-dimensional network structure, and in the coordination polymer 6, the two metal centers were connected by bridging coordination fashions of oxalic acid ligand, forming one-dimensional chain. In addition, the photocatalytic activity of a series of covalent heterojunction coordination polymers was studied. [ABSTRACT FROM AUTHOR]

Three coordination polymers of zinc(II) and cadmium(II) of formula {[Zn(bipy)(NIPH)]·5HO} ( 1), {[Cd(bipy)(NIPH)]·2HO } ( 2) and {[Cd(bipy)(BDAC)(NO)](NO)·6HO} ( 3) (NIPH = 5-nitro-isophthalic acid, HBDAC = 1,4-benzenediacrylic acid and bipy = 2,2′-bipyridine) have been synthesized and structurally characterized by X-ray single crystal diffraction analysis. All the complexes display 1D coordination polymers where M(bipy) units are connected by dicarboxylate anions(and also by nitrate in 3)acting as bridging ligands. While in 1 and 3 a zig-zag chain is generated, in case of 2 a double linear chain is formed by the two crystallographic distinct Cd atoms. In solid state all the complexes expand the dimensionality to 3D by means of π-π interactions among π rings and H-bonds generated by lattice water molecules. The fluorescence study indicates intraligand π-π* charge transfer is the reason for emission in all the complexes. [ABSTRACT FROM AUTHOR]

A new family of eight ruthenium(II)-cyclopentadienyl bipyridine derivatives, bearing nitrogen, sulfur, phosphorous and carbonyl sigma bonded coligands, has been synthesized. Compounds bearing nitrogen bonded coligands were found to be unstable in aqueous solution, while the others presented appropriate stabilities for the biologic assays and pursued for determination of IC 50 values in ovarian (A2780) and breast (MCF7 and MDAMB231) human cancer cell lines. These studies were also carried out for the [ 5 : HSA] and [ 6 : HSA] adducts (HSA = human serum albumin) and a better performance was found for the first case. Spectroscopic, electrochemical studies by cyclic voltammetry and density functional theory calculations allowed us to get some understanding on the electronic flow directions within the molecules and to find a possible clue concerning the structural features of coligands that can activate bipyridyl ligands toward an increased cytotoxic effect. X-ray structure analysis of compound [Ru(η 5 -C 5 H 5 )(bipy)(PPh 3 )][PF 6 ] ( 7 ; bipy = bipyridine) showed crystallization on C2/c space group with two enantiomers of the [Ru(η 5 -C 5 H 5 )(bipy)(PPh 3 )] + cation complex in the racemic crystal packing. [ABSTRACT FROM AUTHOR]

[Ba(5,5´-dcbipy)(μ-H2O)2(H2O)2]n(1) complex was obtained from the reaction of one equivalent of 2,2'-bipyridine-5,5'-dicarboxylic acid (5,5´-dcbipy.H2) and one equivalent of ethylene diamine (en) with one equivalent of BaCl2.2H2O in water. This complex was characterized by elemental analysis, IR, UV-Vis, and luminescence spectroscopy and its structure was studied by the single-crystal X-ray diffraction method. The thermal stability of1was studied by thermogravimetric and differential thermal analyses. [ABSTRACT FROM AUTHOR]

Determining the mechanism of metal–organic framework (MOF) crystal growth is important for the development of more efficient and reliable synthetic methods. Resonance Raman spectroscopy has been used for the first time to detect interactions in solution between metal ions and bridging ligands as MOFs form. UV excitation (229 nm) produced strong resonance enhancement of 4,4′-bipyridine (bpy) vibrational bands and showed that soluble Co2+-bpy species formed in solution prior to the growth of MOF crystals from bpy and Co(NO3)2. The results of the Raman experiments informed the development of faster methods for synthesizing [Co2(bpy)3(NO3)4]n 2D bilayer and [Co(bpy)(NO3)2(H2O)2]n 1D chain MOFs. [ABSTRACT FROM AUTHOR]

The efficient preparation of four C3-symmetric (star-shaped) pyridine and bipyridine derivatives is reported. The key steps are Suzuki couplings of 4-pyridyl nonaflates with 4-acetyl-phenylboronic acid followed by an acid-promoted cyclocondensation reaction converting the methyl ketone moiety into the central benzene ring of the target compounds. Based on STM studies at a graphite–solution interface the twodimensional arrangements of the compounds are discussed, showing the influence of the pyridine substitution pattern. [ABSTRACT FROM AUTHOR]

A 2,2′-bipyridine-appended ferrocene rotor, 1,1′-di(5-yl-ethynyl-2,2′-bipyridine)ferrocene, can be switched from a folded/stacked (syn) conformation to an extended/unstacked (anti) conformation by the addition of [Cu(CH3CN)4](PF6) and 6,6′-dimesityl-2,2′-bipyridine. This extension and contraction process was completely reversible and could be triggered either chemically or electrochemically. [ABSTRACT FROM AUTHOR]

Complexation of two types of dicationic bipyridium guests, paraquat derivatives and bis(N-mono-substituted bipyridine) cations, by a negatively charged carboxylato-biphen[3]arene (CBP3) in water is reported. CBP3 could strongly interact with these guests, where charge-transfer and electrostatic interactions play important roles. [ABSTRACT FROM AUTHOR]

A new series of photoactive metallocyclodextrins with increased fluorescence intensity upon binding with ssDNAs/aptamers has been demonstrated to sensitively and selectively detect lysozyme. The detection mechanism relies on the formation of an aptamer–lysozyme complex, which leads to reduction of fluorescence intensity. [ABSTRACT FROM AUTHOR]

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]

New unsymmetric 5,6´-diaryl-2,2´-bipyridines were synthesized in high yields using a 1,2,4-triazine methodology. Their photophysical properties were studied. [ABSTRACT FROM AUTHOR]

Novel acrylate copolymer with carbazole pendant groups and derivatives of bipyridine as side chains were synthesized, in which derivatives of bipyridine as electro-optic chromophores and carbazolyl as photoconductive moiety were covalently linked to the acrylate backbone. 2-(9-Carbazolyl)ethyl methacrylate (CEM) and 2-methylacrylic acid 2-{4,4'-dimethyl-5'-[2-(5-methyl-thiophen-2-yl)-vinyl]- [2,2']bipyridinyl-5-yl}-ethyl ester (BiPy) were synthesized and then copolymerized to give (99:1), (98:2), and (92:8 mol/mol) CEM/BiPy copolymers. Solutions of the copolymers in dioxane were examined for their photoluminescence properties. [ABSTRACT FROM AUTHOR]

We report a structure-property study on phosphoryl-bridged viologen analogues with a remarkably low reduction threshold. Utilizing different benzyl groups for N-quaternization, we were able to confirm the p-benzyl substituent effect on the electronic tunability of the system while maintaining the characteristic chromic response of viologens with two fully reversible one-electron reductions. Due to the considerably increased electron-acceptor properties of the phosphoryl-bridged bipyndine precursor, N-benzylation was found to be very challenging and required the development of new synthetic strategies toward the target viologen species. This study also introduces a new and convenient way for the anion exchange of viologen systems by utilizing methyl triflate. Finally, the practical utility of the new species was verified in simplified proof-of-concept electrochromic devices. [ABSTRACT FROM AUTHOR]

The incorporation of a rhenium atom within an extended helical π-conjugated bi-pyridine system impacts the chiroptical and photophysical properties of the resulting neutral or cationic complexes, leading to the first examples of rhenium-based phosphors that exhibit circularly polarized luminescence. [ABSTRACT FROM AUTHOR]

We present the study of nano- and microparticles of the Fe(Me2-bpy)2(NCSe)2 spin-crossover complex prepared from the diamagnetic precursor [Fe(Me2-bpy)3](NCSe)2·S. Two solvates of the latter were characterized by single-crystal X-ray structures at 100 K (S = 2MeOH or 3H2O). The extraction of one Me2-bpy per metal ion in [Fe(Me2-bpy)3](NCSe)2·S was achieved either by thermolysis at temperature higher than 150 °C or by precipitation in an anti-solvent, leading to a polycrystalline or particulate powder of Fe(Me2-bpy)2(NCSe)2. This chemical conversion was investigated by TGA, powder X-ray diffraction, IR, Raman and magnetic measurements. The S = 0 ↑S = 2 spin-crossover of Fe(Me2-bpy)2(NCSe)2 centered at ca. 340 K is almost complete at low temperature (HS residue ≤ 5% below 250 K) while at 370 K, the HS fraction can be estimated at ∼0.7. These features are essentially preserved whatever be the size of particles (56, 460 and 1200 nm) as a consequence of the weak cooperativity of the process occurring at high temperature, the crystallinity and the molecular nature of particles. This approach leading to dispersion of small particles in a polymer is suitable for the preparation of materials of optical quality, via the stabilization and processing of nanoparticles in convenient matrices to form thin films. [ABSTRACT FROM AUTHOR]

The synthesis, stability, and photophysical properties of [2 + 1] Re(I)/Tc(I) complexes derived from bipyridine and a series of imidazole derivatives were investigated as a means of identifying complexes suitable for creating targeted isostructural optical/nuclear molecular imaging probes. To prepare the desired complexes, [Re(CO)3(H2O)3]Br was combined with 2,2'-bipyridine (bipy) to give [Re(CO)3(bipy)Br], which in turn was converted to the desired complexes by treatment with functionalized imidazoles, yielding crystal structures of two new Re complexes. The corresponding 99mTc complexes [99mTc(CO)3(bipy)(L)]+ (L = imidazole derivatives) were prepared by combining [99mTc(CO)3(bipy)(H2O)]Cl with the same series of ligands and heating at 40 or 60 °C for 30 min. Quantitative transformation to the final products was confirmed in all cases by HPLC, and the nature of the complexes was verified by comparison to the authentic Re standards. Incubation in saline and plasma, and amino acid challenge experiments showed that N-substituted imidazole derivatives, bearing electron donating groups, exhibited superior stability to analogous metal complexes derived from less basic ligands. Imaging studies in mice revealed that with the appropriate choice of monodentate ligand, it is possible to prepare robust [2 + 1] Tc complexes that can be used as the basis for preparing targeted isostructural optical and nuclear probes. [ABSTRACT FROM AUTHOR]

Theoretical calculations (density functional theory with the scalar relativistic ZORA Hamiltonian) have been performed to obtain the energy and Gibbs free energy of formation of cationic 1 : 3 complexes of americium(iii) and europium(iii) with a tri-O-dentate diglycolamide ligand TEDGA (a model of TODGA extractant), as well as the free energy of their partition between water and an organic diluent. The distribution of electron density over the atoms, bonds, and molecular orbitals was analyzed by means of Mulliken population analysis, the localization procedure of natural bond orbitals, and the Quantum Theory of Atoms-in-Molecules. The stabilities of both [M(TEDGA)3]3+ complexes are similar to each other. On the other hand, our recent data for a similar pair of cationic Am/Eu complexes with a softer (HSAB) tetra-N-dentate ligand C2-BTBP show that the [Am(C2-BTBP)2]3+ complex is significantly more stable in aqueous solution than its Eu counterpart. The decisive factor stabilizing the Am3+ complexes over their Eu3+ analogues is the charge transfer from the ligands, somewhat greater on the 6d(AmIII) than on 5d(EuIII) orbitals. The covalency of M–N bonds in the [M(C2-BTBP)2]3+ complexes is greater than that of M–O bonds in [M(TEDGA)3]3+, but the latter is not negligible, in particular in the bonds with the oxygen atoms of the amide groups in TEDGA. The analysis of charge distribution over the whole molecules of the complexes shows that the TEDGA molecule is not hard as expected, but a relatively soft Lewis base, only slightly harder than BTBP. This conclusion has been confirmed by the calculation of the chemical hardness of the ligands. Moreover, the comparison of the results of bonding analysis with the calculated energies of complex formation in water and in the gas phase allows us to conclude that the population analysis, QTAIM topological parameters, and SOPT stabilization energy, as well as Wiberg and overlap-weighted NAO indices are the tools for analyzing the covalency rather than the total bond strength. [ABSTRACT FROM AUTHOR]

The binuclear complex {[UO(5,5′-dmbpy)(NO)](μ-O)}, where 5,5′-dmbpy is 5,5′-dimethyl-2,2′-bipyridine, was prepared by reaction of UO(NO).6HO with 5,5′-dimethylbipyridine in 1:1 methanol-acetonitrile. The complex was characterized by FT-IR and UV-visible spectroscopy, cyclic voltammetry (CV), and single-crystal X-ray diffraction analysis. The crystal data for {[UO(5,5′-dmbpy)(NO)](μ-O)} at 25 °C are: monoclinic, space group P2 /n with a = 9.8(7) Å, b = 16.0 (12) Å, c = 10.3 (8) Å, β = 111.023(9)° and Z = 2. [ABSTRACT FROM AUTHOR]

The corrosion inhibition characteristics of 2,2′-bipyridine (BIPY) and 2,2′-bipyridine-3,3′-dicarboxylic acid (BIDA), on carbon steel in sulphuric acid solutions was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques at 20°C, 30°C and 40°C. The results indicate that the organic compounds inhibit the corrosion of mild steel in H2SO4 solutions and the extent of inhibition increases with inhibitor concentration and decreases with temperature. A mixed-inhibition mechanism is proposed for the inhibitive effects of the compounds. The order of inhibition efficiency obtained was BIDA>BIPY. There is a good correlation between the quantum chemical parameters and experimentally determined inhibition efficiency of the inhibitors. The adsorption characteristics of the inhibitor were approximated by Temkin isotherm. Morphological study of the carbon steel electrode surface was undertaken by scanning electron microscope (SEM) and the interfacial species formed on the surface in the presence of inhibitors analyzed by Infrared spectroscopy. [ABSTRACT FROM AUTHOR]

The synthesis of Mn-based catalysts to mimic the structural and catalytic properties of the oxygen-evolving complex in photosystem II is a long-standing goal for researchers. An interesting result in this field came with the synthesis of a Mn complex that enables water oxidation driven by the mild single-electron oxidant [Ru(bpy)3]3+. On the basis of hybrid density functional calculations, we herein propose a water oxidation mechanism for this bioinspired Mn catalyst, where the crucial O-O bond formation proceeds from the formal Mn4IV,IV,IV,V state by direct coupling of a MnIV-bound terminal oxyl radical and a di-Mn bridging oxo group, a mechanism quite similar to the presently leading suggestion for the natural system. Of importance here is that the designed ligand is shown to be redox-active and can therefore store redox equivalents during the catalytic transitions, thereby alleviating the redox processes at the Mn centers. [ABSTRACT FROM AUTHOR]

A new triad system featuring one zinc porphyrin and one fullerene moieties attached to a central redox-active Re(I) connector was obtained in remarkable yield by cleverly exploiting a facile two-step synthesis. Detailed description and discussion on the characterization of this multicomponent system and of its parent free-base analogue are presented, along with a kinetic study of the stepwise electron-transfer processes occurring upon visible excitation. [ABSTRACT FROM AUTHOR]

A series of chiral cyclometalated platinum(II) complexes, [Pt((-)-L1)(Dmpi)]Cl ((-)-1), [Pt((+)-L1)(Dmpi)]Cl ((+)-1), [Pt((-)-L2)(Dmpi)]Cl ((-)-2), [Pt((+)-L2)(Dmpi)]Cl ((+)-2), [Pt3((-)-L2)2(Dmpi)4](ClO4)4 ((-)-3), and [Pt3((+)-L2)2(Dmpi)4](ClO4)4 ((+)-3) [(-)-L1 = (-)-4,5-pinene-6'-phenyl-2,2'-bipyridine, (+)-L1 = (+)-4,5-pinene-6'-phenyl-2,2'-bipyridine), (-)-L2 = (-)-1,3-bis(2-(4,5-pinene)pyridyl)benzene, (+)-L2 = (+)-1,3-bis(2-(4,5-pinene)pyridyl)benzene, Dmpi = 2,6-dimethylphenyl isocyanide], have been designed and synthesized. In aqueous solutions, (-)-1 and (+)-1 aggregate into one-dimensional helical chain structures through Pt···Pt, π-π, and hydrophobic-hydrophobic interactions. (-)-3 and (+)-3 represent a novel helical structure with Pt-Pt bonds. The formation of helical structures results in enhanced and distinct chiroptical properties as evidenced by circular dichroism spectra. Circularly polarized luminescence (CPL) was observed from the aggregates of (-)-1 and (+)-1 in water, as well as (-)-3 and (+)-3 in dichloromethane. The CPL activity can be switched reversibly (for (-)-1 and (+)-1) or irreversibly (for (-)-3 and (+)-3) by varying the temperature. [ABSTRACT FROM AUTHOR]

Using a fluorinated 1,1,1-trifluoro-2,4-pentanedione (Htfac) ligand and either 2,2'-bipyridine (bipy), bathophenanthroline (bath) or 5-nitro-1,10-phenanthroline (5NO2phen) as an ancillary ligand, three new ternary erbium(III) octacoordinated complexes have been synthesized. The single crystal structures of the new complexes (namely [Er(tfac)3(bipy)], [Er(tfac)3(bath)] and [Er(tfac)3(5NO2phen)]) have been determined and their properties have been investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and thermodynamic analysis. After ligand-mediated excitation of these complexes in the UV, they all show the characteristic near-infrared (NIR) luminescence of the corresponding Er3+ ion at 1532 nm. The same emission in the C-band transmission window can also be obtained from the solutionprocessed organic light-emitting diodes (OLEDs) with structure: glass/ITO/PEDOT:PSS/[Er(tfac)3(N,Ndonor)]/ Ca/Al. In spite of the fact that the photoluminescence intensity of [Er(tfac)3(5NO2phen)] is stronger than those of [Er(tfac)3(bipy)] and [Er(tfac)3(bath)], the best electroluminescence results correspond to the OLED based on the [Er(tfac)3(bath)] complex, as a consequence of the superior electron transport capabilities of bathophenanthroline. [ABSTRACT FROM AUTHOR]

Three co-crystals of celecoxib (CEL) and bipyridine derivatives were synthesized based on the synthon design approach and structurally characterized. The resulting two-component complexes have different unit cell parameters and noticeably different packing patterns. Surprisingly, when different organic solvents are introduced into the binary-host crystal systems, six isostructural three-component crystals are obtained. These isomorphic complexes are formed by CEL with two different sets of bipyridine co-formers containing various solvent molecules. A robust H-bonding framework between CEL dimer molecules is found to tolerate subtle changes in the structures of the co-formers and guest solvent molecules. The physicochemical properties of these isomorphic co-crystals are fully examined and compared with their corresponding non-solvate forms. The desolvation mechanism and relative thermodynamic stabilities are also discussed. [ABSTRACT FROM AUTHOR]

The sulfonated bipyridine derivative disodium 6,6′-bis(sulfonatomethyl)-2,2′-bipyridine [Na2(smbipy)] was synthesized, and its complexation behaviour towards divalent 3d metals in aqueous solution was explored. The complexes of late 3d metals [M(smbipy)(H2O)2] ·H2O (M = Co, Ni, Zn) and [Cu(smbipy)(H2O)] are sparingly soluble in water, and their crystal structures show fourfold equatorial coordination (κ4 N, N′, O, O′) of the smbipy ligand. Ammonia-rich solutions of the NiII and CuII aqua complexes yield the decomplexation products [Ni(NH3)6](smbipy), [Ni(NH3)5(H2O)](smbipy) and [Cu(NH3)4](smbipy) ·2H2O. Buffered solutions with a reduced ammonia content lead to [Ni(smbipy)(NH3)2] and [Cu(smbipy)(NH3)3] ·2H2O, and the latter shows twofold coordination of the smbipy ligand through the nitrogen atoms only (κ2 N, N′). When nearly quantitative amounts of ammonia are applied, two closely related complexes with the core motif [(smbipy)Cu(μ-OH)2Cu] form. Crystal structures of all complexes were obtained, and their features are discussed. [ABSTRACT FROM AUTHOR]

In this work, the interactions between a viologen phosphorus dendrimer of generation 0 (VPD) and ATP or 2′-/3′-O-(N′-methylanthraniloyl)-ATP (Mant-ATP) were investigated by NMR and fluorescence spectroscopy methods. ATP and Mant-ATP were used as model molecules of purine and pyrimidine nucleoside analogues (NAs), which are antimetabolites commonly used in anticancer therapy. Complexes of VPD with NAs may help to overcome severe limitations of NAs associated with their low solubility, stability or resistance to cancer cells. The aim of the presented study was to evaluate the stoichiometry and the mechanism of formation of complexes between dendrimers and nucleotides: ATP and Mant-ATP. Moreover, we examined the efficiency of complex formation in relation to temperature, the type of solvent, NaCl concentration, pH and environment polarity. It was observed that viologen phosphorus dendrimers form complexes with ATP and Mant-ATP with high efficiency. Obtained complexes are stabilized by electrostatic and aromatic–aromatic interactions as driving forces. [ABSTRACT FROM AUTHOR]

An electrochromic device containing heptyl viologen, poly(3,4-ethylenedioxythiophene) (PEDOT), TiO2 and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was fabricated. Both heptyl viologen and PEDOT are electrochromic materials with different spectra at its colored states. The transmission spectrum was measured in different voltages in a wide wavelength range from near infrared to near ultraviolet. By combining PEDOT and heptyl viologen, a high on/off contrast was obtained with almost zero transmittance in a dark state. Also, the TiO2 layer increased optical transmittance change, as it provides a large surface area where the heptyl viologen was reduced to be colored. On the other hand, the TiO2 layer did not decrease the on/off switching time. [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]

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]

Self-assembly of 4,4′-bipyridine (bpy) with arene-ruthenium building blocks and 2,2′-bisbenzimidazole (H2BiBzIm) in the presence of AgOTf (OTf = OSO2CF3) afforded tetranuclear cations of the type [Ru4(η6-arene)4(bpy)2(BiBzIm)2]4+(arene = p-iPrC6H4Me1, C6Me62), while similar reactions by use of [(η6-C6Me6)Ru(μ-Cl)Cl]2and excess AgOTf led to isolation of a cationic coordination network {[Ru4(η6-C6Me6)4(bpy)2(BiBzIm)2·Ag2(OTf)4]2+}n(3), which could also be obtained by treatment of [2][OTf]4with AgOTf in methanol. Complex3is constructed byπcoordination of BiBzIm(η2-carcon) with Ag(I). The coordination geometry around the silver(I) ion is pseudo-tetrahedral (taking the C=C group as one ligand). Self-assembly of only two components: [(η6-C6Me6)Ru(μ-Cl)Cl]2reacted with the 3-pyridyl-bian (mPy-bian) linker in the presence of limited AgOTf to give a chloro-bridged metalla-rectangle [Ru4(η6-C6Me6)4(μ-Cl)4(mPy-bian)2Ag]5+(4), which enclosed a silver in the center. The coordination geometry around silver(I) in4is unusual square planar. The molecular structures of1–4were confirmed by X-ray crystallography along with other spectroscopic properties. A 1-D coordination network {[Ru4(η6-C6Me6)4(bpy)2(BiBzIm)2·Ag2(OTf)4]2+}ncontaining silver triflate interaction was synthesizedviaself-assembly of [(C6Me6)RuCl2]2, 4,4′-bipyridine, and 2,2′-bisbenzimidazole in the presence of excess AgOTf or through direct reaction of metalla-rectangle [Ru4(C6Me6)4(bpy)2(BiBzIm)2]4+and AgOTf. [ABSTRACT FROM AUTHOR]

A mild heterogeneous oxidizing agent, cupric bromide has been utilized for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridine derivatives in excellent yields with the isolation of products by simple work-up procedure. [ABSTRACT FROM AUTHOR]

A novel organic--inorganic hybrid monocapped/bicapped Keggin structure [CoII(bpy)3]6(H2bpy)[(CoIIbpy)2(PMo8VIMo4O40)]3 [(CoIIbpy)-(PMo8VIMo4V O40)]·16H2O (bpy = 2,2'-bipyridine) was synthesized and shown to be an efficient visible light-driven catalyst for water oxidation. [ABSTRACT FROM AUTHOR]