Search

The dinuclear oxidovanadium(IV/V) complex, [V2(HS2O8)O3(C18H24N2)2]·CH3CN or [V2O2(μ-O)(μ-H(SO4)2)(4,4′-tBubpy)2]·CH3CN (4,4′-tBubpy = 4,4′-di-tert-butyl-2,2′-bipyridine), has crystallographic C2 symmetry and exhibits a distorted octahedral geometry around the vanadium center, where the two 4,4′-tBubpy ligands are nearly orthogonal to each other. The two vanadium ions are linked by an oxo anion and a unique protonated sulfate anion [H(SO4)23−]. In the crystal, intermolecular C—H...π and π–π interactions between the 4,4′-tBubpy ligands are present, leading to a three-dimensional network.

The reaction of [RuNO(Py)2Cl2OH] with bipyridine in water–ethanol media results in trans-(NO, OH)-[RuNO(Py)(Bpy)ClOH]+ with an acceptable yield (60–70%) as hexafluorophosphate salt. Further treatment of the hydroxy-complex with concentrated HF quantitatively leads to trans-(NO, F)-[RuNO(Py)(Bpy)ClF]+. Despite the chirality of both coordination spheres, the hexafluorophosphate salts crystallized as racemates. A NO-linkage isomerism study of the obtained complexes was performed at 80 K with different excitation wavelengths (405, 450, 488 nm). The most favorable wavelengths for the MS1 isomer (Ru-ON) formation were 405 and 450 nm, where the linkage isomer populations were 17% and 1% for [RuNO(Py)(Bpy)ClOH]PF6 and [RuNO(Py)(Bpy)ClF]PF6. The shift of the excitation wavelength to the green (488 nm) sharply decreased the MS1 population. The IR-spectral signatures of MS1 were registered. Reverse-transformation Ru-ON (MS1)-Ru-NO (GS) was investigated for [RuNO(Py)(Bpy)ClOH]PF6 using IR and DSC techniques that made it possible to determine the kinetic parameters (Ea and k0) and decay temperature.

Treatment of the ligand 3,4,5,6-tetraphenyl-2,2´-bipyridine (LH) VIII with HAuCl4 in acetonitrile afforded the cyclometallated square-planar Au(III) complex [LAuCl]ClO4 (7) containing the anionic tridentate (N∧N∧C) ligand, via orthometallation. Treatment of (7) with 4-dimetylaminopyridine (DMAP) and AgClO4 in acetonitrile produced [LAu(DMAP)][ClO4]2 (8), showing the same coordination mode. Analogous complex [LAu(PPh3)][ClO4]2 (9) was prepared by using PPh3 instead of DMAP. Reaction of VIII with HAuCl4 at room temperature in aqueous acetonitrile resulted the non-cyclometallated Au(III) complex [(LH)AuCl2]Cl (10), in which VIII is a bidentate (N∧N) ligand. Treatment of VIII with the filtrate obtained by mixing [AuCl(PPh3)] and AgO2CCF3 in acetone resulted the non-cyclometallated Au(I) complex [(LH)Au(PPh3)]O2CCF3 (11) having bidentate (N∧N) ligand. Above complexes were adequately characterized by a combination of elemental analysis, IR, Mass and NMR spectroscopy. The X-ray crystal structures of (7) and (8) were determined.

The synthesis of the complex containing manganese(II), bipyridine (bipy) as a ligand, and an anionic trifluoromethane sulfonate (triflate) is reported. The corresponding metal content, conductance, and DTG-TGA of the complex lead to the formula of [Mn(bipy)3](triflate)2·5.5H2O. The fully high-spin magnetic moment is observed, corresponding to five unpaired electrons in the metal ion. The electronic spectral bands suggest the three possible spin-forbidden transitions of the sextet to quartet states. The mode of vibrations of the IR spectrum supports the typical ring of bipy, and the triflate. The images of SEM-EDX indicate the presence of the corresponding elemental content and reflect the relatively high crystallinity, as it is evidenced in the profile of the corresponding powdered diffractogram. The refinement of powdered XRD following the Le Bail program suggests being structurally triclinic symmetry of P21/c. This complex shows inhibition of bacterial activity against S. aureus and E. coli.

In the present study, a zinc(II) complex with 4-ethynyl-2,2’-bipyridine (ebpy), [Zn(ebpy)Cl2], was synthesized and characterized by spectroscopic (1H-NMR, IR and UV–Vis) methods and molar conductivity measurement. The crystal structure of the [Zn(ebpy)Cl2] complex was determined by single-crystal X-ray diffraction analysis, confirming the bidentate coordination of the ebpy ligand through its two nitrogen atoms, while the remaining two coordination sites are occupied by two chloride ions. With the aim to investigate the reactivity of the synthesized zinc(II) complex toward biologically important molecules, its binding affinity to calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) was studied by fluorescence emission spectroscopy. From the obtained results, it can be concluded that [Zn(ebpy)Cl2] complex binds to bovine serum albumin reversibly, while the combination of ethidium bromide (EthBr) and Hoechst 33258 (2’-(4-hydroxyphenyl)-5-[5-(4-methylpiperazine- 1-yl)benzimidazo-2-yl]-benzimidazole) competitive binding study suggests that this complex interacts with ct-DNA through the minor groove binding, which is in agreement with molecular docking study.

The thermal decomposition of (XMebpyH)3(H3O)[W(CN)8]·3H2O (where XMebpy denotes 4Mebpy 4,4′-dimethyl-2,2′-bipyridine or 5Mebpy 5,5′-dimethyl-2,2′-bipyridine) in glycerol results in the coordination of XMebpy. Salts of the anion formula [W(CN)6(XMebpy)]2− were isolated for PPh4+ and/or AsPh4+ cations as well as for K+, Rb+, and Cs+ ones. X-ray single-crystal analyses for tetraphenyl-phosphonium and tetraphenyl-arsonium cations are described. IR, UV-Vis, and cyclic voltammetry data are presented. The results were compared with those for [W(CN)6(bpy)]2− (bpy = 2,2′-bipyridine) ion salts.

Reaction of 1,10-phenanthroline-5,6-dione V with 1,3-diphenyl propan-2-one afforded the keto-alcohol VI. Treatment of VI with alkynes, di(3-thienyl) acetylene and di(4-tert-butylphenyl) acetylene yielded 5,8-diphenyl-6,7-di(3-thienyl)-1,12-diaza-triphenylene L1 and 6,7-di(4-tert-butylphenyl)-5,8-diphenyl-1,12-diazatriphenylene L2, respectively. [ReCl(CO)5] reacted with N^N-donor ligands L1-L6 to produce fac-tricarbonylrhenium(I) complexes (20)-(25) in good yields as coloured solids. Treatment of [ReCl(CO)5] with the bulky P^N ligand L7 formed the neutral complex fac-[ReCl(CO)3(L7)] (26) whilst with the azine diphosphine Z,Z-L8 afforded the cationic complex fac-[Re(CO)3(E,Z-L8)]Cl (27a), where L8 is a tridentate ligand. The chloride anion of the complex (27a) was replaced by treating it with NH4PF6 into fac-[Re(CO)3(E,Z-L8)]PF6 (27b). Above complexes were characterized by a combination of elemental analysis, IR, Mass and NMR spectroscopy.

A supramolecular self-assembly of semiconducting polymers and small molecules plays an important role in charge transportation, performance, and lifetime of an optoelectronic device. Tremendous efforts have been put into the strategies to self-organize these materials. In this regard, here, we present the self-organization of terthiophene and its methyl alcohol derivative with 4,4′-bipyridine (44BiPy). An unexpected 2D layered organization of 5,5″-dimethyl-2,2′:5′,2″-terthiophene (DM3T) and 44BiPy was obtained and analyzed. Single-crystal X-ray diffraction analysis revealed that DM3T and 44BiPy consist of stacked, almost independent, infinite 2D layers while held together by weak hydrogen bonds. In addition to this peculiar supramolecular arrangement of these compounds, the investigation of their photophysical properties showed strong fluorescence quenching of DM3T by 44BiPy in the solid state, suggesting an efficient charge transfer. On the other hand, the methyl alcohol derivative of terthiophene, DM3TMeOH, organized in a closed cyclic motif with 44BiPy via hydrogen bonds.

The quest for potential antiviral drug for the ongoing SARS-CoV-2 pandemic has posed a serious challenge to the scientific community. While several potential drugs have been proposed from organic molecular perspective, the uses of 3D metal complexes of bipyridine ligand have been recently proven to be potential coordinate covalent inhibitors for the SARS-CoV-2 main 3-Chymotrypsin-like protease (3CLpro). Herein, we present detailed DFT studies, in silico molecular docking, and multilinear regression analysis (MLRA) investigations of eight (8) selected biologically active Rhenium Tricarbonyl complexes designed and modeled based on the results of Karges and co-workers. The atomistic DFT modeling was conducted to investigate the reactivity, structural stability, and electronic properties based on frontier molecular orbitals (FMO), natural bond orbitals (NBO), interaction energies, density of states (DOS), charge distributions, and molecular thermochemical parameters. Molecular docking simulations were performed to study the binding interactions between the selected biologically active complexes and the target SARS-CoV-2 viral protein, 3CLPRO. The best quantitative structure-activity relationship (QSAR) was established to demonstrate the correlations between the DFT calculated descriptors and the in vitro biological activities (IC50) of structures.

Single-crystal X-ray structure determinations are reported for four lanthanide complexes, [Dy(bipy)2Cl2(OH2)2]Cl.H2O (bipy = 2,2′-bipyridine), 1; [La2(phen)2(O2CCH3)4(NO3)2] (phen = 1,10-phenanthroline), 2; [Lu(terpy)(O2CCH3)3].NaNO3 (terpy = 2,2′;6′,2″-terpyridine) 3; and [Lu(phen)(O2CH)3(OH2)].H2O, 4. Dispersion interactions within the stacked arrays of coordinated aza-aromatic units found in all four complexes appear to be a significant structural influence in the solid state. For complex 1, there are additional interactions beyond dispersion, which suggests that it may be the means whereby the Δ and Λ forms contribute to the overall chiral nature of the crystal. These weak intermolecular interactions were investigated in detail using the Hirshfeld surface analysis.

β-diketiminate coordinated magnesium(I) compounds, [{(ArNacnac)Mg}2] (ArNacnac = [(ArNCMe)2CH]– (Ar = 2,6-diisopropylphenyl (Dip) or mesityl (Mes)), have been utilized as reducing agents in reactions with the redox active 1,4-diazabutadiene, (ButNCH)2 (ButDAB), and 2,2’-bipyrine (bipy). These reactions led to one-electron reductions of the unsaturated substrate, and formation of the highly colored radical complexes, [(ArNacnac) Mg(ButDAB•)] and [(MesNacnac)Mg(bipy•)(bipy)]. The X-ray crystal structures of the compounds reveal each to possess one singly reduced ButDAB or bipy ligand.

This short note describes the synthesis of compound 6,6′-di-(2″-thiophenol)-2,2′-bipyridine from its methyl phenyl sulfane precursor via deprotection of the methyl groups. The product as well as the intermediate in the synthetic route have been characterized by UV-Vis spectroscopy, 1H- and 13C-NMR spectroscopy, FT-IR spectroscopy, and HR-MS analysis. This work presents a rare example of tetradentate chelators that bears pyridyl backbones and thiophenol donors for the coordination with 3d-transition metal cations.

The cyclic voltammograms of a series of substituted terpyridine ligands are presented, showing that reduction occur generally below −2 V versus the redox potential of ferrocene. Density functional theory (DFT) calculated energies and the theoretically calculated reduction potentials of a large series of substituted oligo(aza)pyridine ligands (terpyridine, bipyridine and phenanthroline) are determined and related to experimentally measured reduction potentials. A linear relationship is observed for the reduction potential of tpy ligands and the sum of the Hammett constant of the substituents on the ligands. It was found that the reduction potential of terpyridines relate linearly with various DFT calculated energies. It was further demonstrated that different oligo(aza)pyridines, namely phenanthrolines, bipyridines and the terpyridine ligands of this study, follow the same “reduction potentials – DFT energies” relationships.

Treatment of 3,4,5,6-tetraphenyl-2,2′-bipyridine (LH) (7) with [PtCl2(dmso)2] (dmso = dimethyl sulfoxide) in chloroform afforded the cyclometallated square-planar platinum(II) complex [PtCl(L)] (8) and the octahedral Pt(IV) complex mer-[PtCl3(L)] (9) containing an anionic tridentate (C^N^N) ligand. The chloride of (8) can be easily replaced by trifluoroacetate to yield [(L)PtO2CCF3] (10). Reaction of (8) with the alkyne HC≡CC6H4But-4 resulted in the formation of [(L)PtC≡CC6H4But-4] (11). Treatment of (8) with 4-dimetylaminopyridine (DMAP) and PPh3 in dichloromethane, and the subsequent addition of NH4PF6 in methanol produced the salts [Pt(DMAP)(L)]PF6 (12) and [Pt(PPh3)(L)]PF6 (13), respectively. In a similar manner, reaction of (8) with 0.5 equiv. of bis(diphenyl-phosphino)methane (dppm) formed the dppm-bridged binuclear dicationic salt [(L)Pt(- dppm)Pt(L)][PF6]2 (14).

The response to the high demand for decreasing the amount of CO2 in the atmosphere, a new polyaminal-based polymer network was designed and successfully prepared through one-pot polycondensation reaction of melamine and [2,2′-Bipyridine]-5,5′-dicarbaldehyde. The formation of the polymer structure was confirmed by FT-IR, solid-state 13C NMR, and powder-X-ray diffraction. The porous properties of the polymeric structure were confirmed by field-emission scanning electron microscope and N2 adsorption–desorption methods at 77 K. The prepared polymer can take up 1.02 mmol/g and 0.71 mmol/g CO2 at 273 K and 298 K, respectively, despite its relatively modest Brunauer–Emmett–Teller (BET) surface area (160.7 m2/g), due to the existence of superabundant polar groups on the pore surfaces.

The solvated centrosymmmtric title compound, [Li2(C24H34O4P)2(C10H8N2)2]·2C7H8, was formed in the reaction between {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) and 2,2′-bipyridine (bipy) in toluene. The structure has monoclinic (P21/n) symmetry at 120 K and the asymmetric unit consists of half a complex molecule and one molecule of toluene solvent. The diaryl phosphate ligand demonstrates a μ-κO:κO′-bridging coordination mode and the 2,2′-bipyridine ligand is chelating to the Li+ cation, generating a distorted tetrahedral LiN2O2 coordination polyhedron. The complex exhibits a unique dimeric Li2O4P2 core. One isopropyl group is disordered over two orientations in a 0.621 (4):0.379 (4) ratio. In the crystal, weak C—H...O and C—H...π interactions help to consolidate the packing. Catalytic systems based on the title complex and on the closely related complex {Li[(2,6-iPr2C6H3-O)2POO](MeOH)3}(MeOH) display activity in the ring-opening polymerization of ∊-caprolactone and l-dilactide.

The introduction of basic groups in the polybenzimidazole (PBI) main chain or side chain with low phosphoric acid doping is an effective way to avoid the trade-off between proton conductivity and mechanical strength for high temperature proton exchange membrane (HT-PEM). In this study, the ethyl imidazole is grafted on the side chain of the PBI containing bipyridine in the main chain and blended with poly(2,2′-[p-oxydiphenylene]-5,5′-benzimidazole) (OPBI) to obtain a series of PBI composite membranes for HT-PEMs. The effects of the introduction of bipyridine in the main chain and the ethyl imidazole in the side chain on proton transport are investigated. The result suggests that the introduction of the imidazole and bipyridine group can effectively improve the comprehensive properties as HT-PEM. The highest of proton conductivity of the obtained membranes under saturated phosphoric acid (PA) doping can be up to 0.105 S cm−1 at 160 °C and the maximum output power density is 836 mW cm−2 at 160 °C, which is 2.3 times that of the OPBI membrane. Importantly, even at low acid doping content (~178%), the tensile strength of the membrane is 22.2 MPa, which is nearly 2 times that of the OPBI membrane, the proton conductivity of the membrane achieves 0.054 S cm−1 at 160 °C, which is 2.3 times that of the OPBI membrane, and the maximum output power density of a single cell is 540 mW cm−2 at 160 °C, which is 1.5 times that of the OPBI membrane. The results suggest that the introduction of a large number of nitrogen-containing sites in the main chain and side chain is an efficient way to improve the proton conductivity, even at a low PA doping level.

Diarylethene is a prototypical molecular switch that can be reversibly photoisomerized between its open and closed forms. Ligands bpy-DAE-bpy, consisting of a phenyl-diarylethene-phenyl (DAE) central core and bipyridine (bpy) terminal substituents, are able to self-organize. They are investigated by scanning tunneling microscopy at the solid–liquid interface. Upon light irradiation, cooperative photochromic switching of the ligands is recognized down to the submolecular level. The closed isomers show different electron density of states (DOS) contrasts, attributed to the HOMO or LUMO molecular orbitals observed. More importantly, the LUMO images show remarkable differences between the open and closed isomers, attributed to combined topographic and electronic contrasts mainly on the DAE moieties. The electronic contrasts from multiple HOMO or LUMO distributions, combined with topographic distortion of the open or closed DAE, are interpreted by density functional theory (DFT) calculations.

The title compound, [Ru(C5H6N2)(C10H8N2)(C15H11N3)](PF6)2 solvent, crystallizes in the triclinic space group P\overline{1} with one dicationic Ru complex, two PF6− anions, and undefined solvent in the asymmetric unit. The cation and anions are linked via N—H...F hydrogen bonding. One PF6− anion is disordered over two positions, with occupancies 0.634 (8) and 0.366 (8). The solvent, which is located in channels in the crystal, is highly disordered. Reflection contributions from the solvent were added to the calculated structure factors using the SQUEEZE routine [Spek (2015) Acta Cryst. C71, 9–18] of the program PLATON, which determined there to be 59 electrons in 264 Å3 treated this way per unit cell. Because the exact identity and amount of solvent were unknown, no solvent was included in the atom list or molecular formula.

Bipyridinium salts are currently very popular due to their perspective applications in redox flow batteries. Hence, we designed and prepared a series of bipyridiniums based on 2,2′-, 3,3′-, and 4,4′-bipyridine and 2,2′-bipyrimidine. The straightforward synthesis utilizes commercially or readily available starting compounds and their direct N-alkylation, mostly using 1,3-propanesultone. All eleven target derivatives with systematically evolved structure were investigated by cyclic voltammetry, which allowed elucidating thorough structure-property relationships. The electrochemical behavior depends primarily on the parent scaffold, type of N-alkylation, number of quaternized nitrogen atoms, planarity, counter ion as well as the used media. Two derivatives featuring quasi-reversible redox processes were further tested on rotating disc electrode and in a flow battery half-cell. 4,4′-Bipyridinium derivative bearing two sultone residues showed better performance and stability in the flow half-cell with small capacity decays of 0.09/0.15% per reduction-oxidation cycle, based on the number of the utilized redox processes (one/two).

Copper (II) complexes containing mixed ligands were synthesized in dimethyl formamide (DMF). The intense cyan emission at an ambient temperature is observed for solid copper (II) complexes with salicylic acid and a 12% quantum yield with a fluorescent lifetime of approximately 10 ms. Hence, copper (II) complexes with salicylic acid are excellent candidates for photoactive materials. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) reveal that the divalent copper metal centers coordinate with the nitrogen and oxygen lone pairs of conjugate ligands. XPS binding energy trends for core electrons in lower-lying orbitals are similar for all three copper (II) complexes: nitrogen 1s and oxygen 1s binding energies increase relative to those for undiluted ligands, and copper 2p3/2 binding energies decrease relative to that for CuCl2. The thermal behavior of these copper complexes reveals that the thermal stability is characterized by the following pattern: Cu(1,10-phenanthroline)(salicylic acid) > Cu(1,10-phenanthroline)(2,2’-bipyridine) > Cu(1,10-phenanthroline)(1-benzylimidazole)2.

The title heptanuclear alkoxido(oxido)vanadium(V) oxide cluster complex, [V7(C10H19O)O17(C18H24N2)3]·CH3CN, was obtained by the reaction of [V8O20(C18H24N2)4] with 4-tert-butylcyclohexanol (mixture of cis and trans) in a mixed CHCl3/CH3CN solvent. The complex has a V7O18N6 core with approximately Cs symmetry, which is composed of two VO4 tetrahedra, two VO6 octahedra and three VO4N2 octahedra. In the crystal, these complexes are linked together by weak intermolecular C—H...O hydrogen bonds between the 4,4′-di-tert-butyl-2,2′-bipyridine ligand and the V7O18N6 core, forming a one-dimensional network along the c-axis direction. Besides the complex, the asymmetric unit contains one CH3CN solvent molecule. The contribution of other disordered solvent molecules to the scattering was removed using the SQUEEZE option in PLATON [Spek (2015). Acta Cryst. C71, 9–18]. The unknown solvent molecules are not considered in the chemical formula and other crystal data.

In the title compound, [Pd(C7H3NO4)(C10H8N2)]·H2O, the PdII cation is four-coordinated in a distorted square-planar coordination geometry defined by the two N atoms of the 2,2′-bipyridine ligand, one O atom and one N atom from the pyridine-2,6-dicarboxylate anion. The complex and solvent water molecule are linked by intermolecular hydrogen bonds. In the crystal, the complex molecules are stacked in columns along the a axis.

[Sm(H2O)4(NO3)3](4,4'-Hbipy)2(NO3)2 (1) (bipy = bipyridine) has been synthesized via hydrothermal reaction and characterized by X-ray diffraction. The title complex features an isolated structure, based on discrete 4,4'-Hbipy moieties, isolated nitrates and [Sm(H2O)4(NO3)3] species. The samarium ion is in a distorted bicapped square antiprism environment, coordinated by three bidentate nitrates and four coordination water molecules. The 4,4'-Hbipy moieties, isolated nitrates and [Sm(H2O)4(NO3)3] species are held together via hydrogen bonds and p…p interactions to form a 3-D supramolecular framework. Luminescent investigation reveals a strong emission in blue region. Optical absorption spectrum of 1 reveals the presence of an optical gap of 3.60 eV.

N-[4-(1-Methyl-1H-imidazol-2-yl)-2,4′-bipyridin-2′-yl]benzene-1,4-diamine was synthesized with a good yield by the reaction of 2′-chloro-4-(1-methyl-1H-imidazol-2-yl)-2,4′-bipyridine with 4-phenylenediamine. The functionalization of the pyridine was accomplished by a nucleophilic aromatic substitution (SNAr) reaction that afforded the target compound. The synthesized compound was characterized by chemical analysis, which includes nuclear magnetic resonance (NMR) (1H-NMR and 13C-NMR), Thin Layer Chromatography-Mass Spectrometry (TLC-MS), high- performance liquid chromatography (HPLC), Gas Chromatography-Mass Spectrometry (GC-MS), and elemental analysis.

Carbonyl complexes with manganese(I) as the central metal are very attractive catalysts. The introduction of redox-active ligands, such as quinones and methyl viologen analogs into these catalysts, would be expected to lead to superior catalyst performances, since they can function as excellent electron carriers. In this study, we synthesized four tricarbonylmanganese(I) complexes containing typical bidentate polypyridyl ligands, including 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy) frameworks bound to redox-active ortho-quinone/catechol or methyl viologen-like units. The molecular structures of the resulting complexes were determined by X-ray crystallography to clarify their steric features. As expected from the infrared (IR) data, three CO ligands for each complex were coordinated in the facial configuration around the central manganese(I) atom. Additionally, the structural parameters were found to differ significantly between the quinone/catechol units. Electrochemical analysis revealed some differences between them and their reference complexes, namely [MnBr(CO)3(phen)] and [MnBr(CO)3(bpy)]. Notably, interconversions induced by two-electron/two-proton transfers between the quinone and catechol units were observed in the phenanthroline-based complexes. This work indicated that the structural and redox properties in tricarbonylmanganese(I) complexes were significantly affected by chemically modified polypyridyl ligands. A better understanding of structures and redox behaviors of the present compounds would facilitate the design of new manganese complexes with enhanced properties.

A novel rice-husk-silica supported n-propyl bipyridinium chloride (RHPrBPCl) has been prepared. Due to the basicity of RHPrBPCl, it was decided to evaluate its catalytic activity in the one-pot preparation of tetrahydrobenzo[b]pyran, dihydropyrano[3,2-c]chromene and dihydropyrano[4,3-b]pyran derivatives. The catalyst was characterized by FT-IR, SEM and TGA analyses. This methodology offers several advantages including easy work-up procedure, high yields of the products, short reaction times, recyclable catalyst and green reaction medium.

One pathway for the preparation of enantiomerically pure compounds from prochiral substrates is the use of metal complex catalysis with chiral ligands. Compared to the other frequently used chiral ligands, chiral 2,2’-bipyridines have been underexploited, despite the data indicating that such ligands have considerable potential in synthetic chemistry. One of those is the so-called Bolm’s ligand, a compound possessing chiral alcohol moieties in the side chains attached to the 2,2’-bipyridine scaffold. Various metal salts have been used in combination with Bolm’s ligand as potent catalysts able to bring about enantioselective alkylations, allylations, conjugate additions, desymmetrization of meso-epoxides, aldol reactions, etc. This review aims to summarize Bolm’s ligand applications in the area of enantioselective synthesis over the last three decades since its preparation.

We have synthesized and examined several complexes of lanthanides with diamides of 2,2′-bipyridyl-6,6′-dicarboxylic acid bearing various hetaryl-based side chains for the elucidation of the effect of the heterocycle on the structure and properties of the ligands. The multigram scale methods for the preparation of various N-alkyl-hetaryls and their diamides were developed. The solid state structure of 6-methyl-2-pyridylamide of 2,2′-bipyridyl-6,6′-dicarboxylic acid possesses a flat structure where the conformation is completely different from that previously observed for N-alkylated 2,2′-bipyridyl-6,6′-dicarboxamides and 2,6-pyridinedicarboxamides. The complexes of new ligands were synthesized and NMR and X-Ray studied their structure in solution and solid state. The results demonstrate that complexes possess the same structures both in solid state and in solution. Stability constants of the complexes were less when comparing with dimethyl-substituted diamides, but higher than for unsubstituted dianilide. Contrarily, the extraction ability of 2-pyridyl-diamide is significantly lower than for corresponding anilide. Specific interaction of extractant with solvent molecules, which is not available for electron-sink pyridine amides, can explain this. The luminescence of new Eu complexes was significantly higher than for all previously 2,2′-bipyridyl-6,6′-dicarboxamides and QY reaches 18%. Asymmetry ratios of Eu complexes were 25% higher when compared other complexes with 2,2′-bipyridyl-6,6′-dicarboxamides, which indicates large deviation from the inversion center.

Formic acid is a promising liquid organic hydrogen carrier (LOHC) since it has relatively high hydrogen content (4.4 wt%), low inflammability, low toxicity and can be obtained from biomass or from CO2. The aim of the present research was the creation of efficient 1 wt% Pd catalysts supported on mesoporous graphitic carbon (Sibunit) for the hydrogen production from gas-phase formic acid. For this purpose, the carbon support was modified by pyrolysis of deposited precursors containing pyridinic nitrogen such as melamine (Mel), 2,2′-bipyridine (Bpy) or 1,10-phenanthroline (Phen) at 673 K. The following activity trend of the catalysts Pd/Mel/C > Pd/C ~ Pd/Bpy/C > Pd/Phen/C was obtained. The activity of the Pd/Mel/C catalyst was by a factor of 4 higher than the activity of the Pd/C catalyst at about 373 K and the apparent activation energy was significantly lower than those for the other catalysts (32 vs. 42−46 kJ/mol). The high activity of the melamine-based samples was explained by a high dispersion of Pd nanoparticles (~2 nm, HRTEM) and their strong electron-deficient character (XPS) provided by interaction of Pd with pyridinic nitrogen species of the support. The presented results can be used for the development of supported Pd catalysts for hydrogen production from different liquid organic hydrogen carriers.

Treatment of cyanoacetanilide derivative 1 with tetracyanoethylene (2) in dioxane/triethylamine furnished 2-pyridone derivative 6. Aminopyridine 9 was obtained by cyclization of compound 1 with ketene dithioacetal 7/EtONa. Cyclocondensation of 1 with malononitrile and/or acetylacetone (1:1 M ratio) gave pyridine derivatives 11 and 13. Ternary condensation of compound 1, aliphatic aldehydes and malononitrile (1:1:1 M ratio) yielded the 2-pyridones 20a and b. Bipyridines 22a–c were prepared by refluxing of compound 21 with active methylene reagents. Cyclization of chromene derivatives 24 and 28 with malononitrile produced the novel chromeno[3,4-c]pyridine 26 and pyrano[3′,2′:6,7]chromeno[3,4-c]pyridine 29.

The title bipyridine derivative, C16H16N2O4, crystallized with two half molecules in the asymmetric unit. The whole molecules (A and B) are generated by inversion symmetry with the mid-points of the bridging C—C bonds of the bipyridine units being located on crystallographic inversion centers. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming sheets parallel to (120). The sheets are linked by C—H...N hydrogen bonds, forming a three-dimensional framework.

The ruthenium carbonyl compounds, Ru(bpy)(CO)2X2 (X = Cl, Br or I) act as neutral halogen bond (XB) acceptors when co-crystallized with 1,4-diiodotetrafluoro-benzene (DITFB). The halogen bonding strength of the Ru-X⋅⋅⋅I halogen bonds follow the nucleophilic character of the halido ligand. The strongest halogen bond occurs between the chlorido ligand and the iodide atoms of the DITFB. All three halogen bonded complexes form polymeric assemblies in the solid state. In Ru(bpy)(CO)2Cl2⋅DITFB (1) and in Ru(bpy)(CO)2Br2⋅DITFB (2) both halido ligands are halogen bonded to only one DITFB donor. In Ru(bpy)(CO)2I2⋅DITFB (3) only one of the halido ligands is involved in halogen bonding acting as ditopic center for two DITFB donors. The polymeric structures of 1 and 2 are isomorphic wave-like single chain systems, while the iodine complexes form pairs of linear chains attached together with weak F⋅⋅⋅O≡C interactions between the closest neighbors. The stronger polarization of the iodide ligand compared to the Cl or Br ligands favors nearly linear C-I⋅⋅⋅I angles between the XB donor and the metal complex supporting the linear arrangement of the halogen bonded chain.

Polymer/inorganic thermoelectric composites have witnessed rapid progress in recent years, but most of the studies have focused on the traditional conducting polymers. The limited structures of traditional conducting polymers restrain the development of organic thermoelectric composites. Herein, we report the preparation and thermoelectric properties of a series of composites films based on SWCNTs and bipyridine-containing polyfluorene derivatives. The value of the power factor around 12 μW m−1 K−2 was achieved for the composite F8bpy/SWCNTs with a mass ratio of 50/50, and the maximum value of 62.3 μW m−1 K−2 was obtained when the mass ratio reached 10/90. Moreover, taking advantage of the bipyridine unit could chelate various kinds of metal ions to form polymer complexes. The enhanced power factor of 87.3 μW m−1 K−2 was obtained for composite F8bpy-Ni/SWCNTs with a mass ratio of 50/50. Finally, the thermoelectric properties of the bipyridine-containing polyfluorene derivative/SWCNT composites were conveniently tuned by chelating with different metal ions.

The crystal structure of the title salt, [Rb(C18H36N2O6)](C10H8N2), consists of Rb+ cations sequestered by a [2.2.2]cryptand molecule and 4,4′-bipyridinidyl radical monoanions. Both entities are centred by special positions: the Rb+ cation is located on a twofold rotation axis and the 4,4′-bipyridinidyl anion is located about an inversion centre, so half of each moiety form the asymmetric unit. The planar 4,4′-bipyridinidyl molecules and the complexed cations are arranged in the sense of a distorted rock salt type of structure.

The title compound, [Ni2Cl2(μ-Cl)2(C10H8N2)2(C3H7NO)2], exists as a centrosymmetric dimer of two octahedral nickel centers. In the crystal, two chloride ions bridge the two nickel centers with one terminal chloride ion bound to each nickel atom. Coupled with a chelating bipyridine ligand and an O-bound N,N-dimethylformamide solvent molecule, each nickel center exhibits an slightly distorted octahedral coordination environment. The meridional chloride ions all sit in equatorial positions, with the bipyridine ligand occupying one equatorial and one axial position, and the N,N-dimethylformamide ligand occupying the final axial position. The 2,2′-bipyridine ligand binds to nickel in a near planar fashion, with the non-H atoms possessing a mean devation from planarity of 0.046 Å. No π–π interactions are observed in the crystal.

In our quest to develop good materials as photosensitizers for photovoltaic dye-sensitized solar cells (DSSCs), cis-dithiocyanato-4-(2,3-dimethylacrylic acid)-2,2'-bipyridyl-4-(9-anthracenyl-(2,3-dimethylacrylic)-2,2'-bipyridyl ruthenium(II) complex, a high molar extinction coefficient charge transfer sensitizer, was designed, synthesized and characterized by spectroscopy and electrochemical techniques. Earlier studies on heteroleptic ruthenium(II) complex analogues containing functionalized oligo-anthracenyl phenanthroline ligands have been reported and documented. Based on a general linear correlation between increase in the length of π-conjugation bond and the molar extinction coefficients, herein, we report the photophysical and electrochemical properties of a Ru(II) bipyridyl complex analogue with a single functionalized anthracenyl unit. Interestingly, the complex shows better broad and intense metal-to ligand charge transfer (MLCT) band absorption with higher molar extinction coefficient (λmax = 518 nm, e = 44900 M−1cm−1), and appreciable photoluminescence spanning the visible region than those containing higher anthracenyl units. It was shown that molar absorption coefficient of the complexes may not be solely depended on the extended π-conjugation but are reduced by molecular aggregation in the molecules.

The reaction of intracomplex proton transfer (44BPY-....HO-H) ® 44BPYH. + OH- that follows the photoreduction of 4,4’-bipyridine (44BPY) into its anion radical 44BPY- in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) is investigated in acetonitrile-water mixtures by using picosecond transient absorption. The dependence of the appearance kinetics of the 44BPYH. radical on the water content reveals a highly diffusional proton transfer process that is controlled by the dynamics of solvation of the released hydroxide ion. The results are interpreted on the basis of a two-step mechanism where an intermediate solvation complex (44BPYH.)OH-(H2O)3 is formed first before evolving toward a final four-water hydration structure OH-(H2O)4.

Heterometallic complexes of chromium (III) with some 3d metals have been synthesized based on nitrilotriacetic acid (H3nta), like M(bpy)2Cr2(OH)2(nta)2·nH2O, where M = Mn2+, Co2+, Ni2+ and Zn2+; bpy = α,α′- bipyridine; n = 8 or 9. Their chemical composition has been determined from the results of the elemental analysis and thermogravimetric study. The coordination modes of the nta3 ̄ ligand and the type of chemical bonds have been proposed basing on IR spectra.

The title hydrated molecular organic salt, C10H10N22+·C10H6O6S22−·2H2O, crystallized with half a bipyridinium cation, half a naphthalene-2,6-disulfonate anion and a water molecule in the asymmetric unit. The whole cation and anion are generated by inversion symmetry, the inversion centers being at the center of the bridging C—C bond of the cation, and at the center of the fused C—C bond of the naphthalene group of the anion. In the crystal, the anions and cations stack alternately along the a axis with π–π interactions [inter-centroid distance = 3.491 (1) Å]. The anions are linked via O—H...O(sulfonate) hydrogen bonds involving two inversion-related water molecules, forming chains along [10-1]. These chains are bridged by bifurcated N—H...(O,O) hydrogen bonds, forming a three-dimensional framework structure. There are also C—H...O hydrogen bonds present, reinforcing the framework structure.

In the title two-dimensional coordination polymer, {[Cu2(C9H3O6)(OH)(C10H8N2)2]·3H2O}n, each of the two independent CuII atoms is coordinated by a bridging OH group, two O atoms from two benzene-1,3,5-tricarboxylate (L) ligands and two N atoms from a 2,2- bipyridine (bipy) ligand in a distorted square-pyramidal geometry. Each L ligand coordinates four CuII atoms, thus forming a polymeric layer parallel to the bc plane with bipy molecules protruding up and down. The lattice water molecules involved in O—H...· O hydrogen bonding are situated in the inner part of each layer. The crystal packing is consolidated by π–π interactions between the aromatic rings of bipy ligands from neigbouring layers [intercentroid distance = 3.762 (3) Å].

We describe neurobiological applications of RuBi-Glutamate, a novel caged-glutamate compound based on ruthenium photochemistry. RuBi-Glutamate can be excited with visible wavelengths and releases glutamate after one- or two-photon excitation. It has high quantum efficiency and can be used at low concentrations, partly avoiding the blockade of GABAergic transmission present with other caged compounds. Two-photon uncaging of RuBi-glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics. With laser beam multiplexing, RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution. RuBi-Glutamate therefore enables the photo-activation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single spine, or single cell, precision.