Crystal structure of Bi(III) complex of a pyridine containing self-assembling system

Bi-MOF Modulating MnO2 Deposition Enables Ultra-Stable Cathode-Free Aqueous Zinc-Ion Batteries

The Mn-based materials are considered as the most promising cathodes for zinc-ion batteries (ZIBs) due to their inherent advantages of safety, sustainability and high energy density, however suffer from poor cyclability caused by gradual Mn²⁺ dissolution and irreversible structural transformation. The mainstream solution is pre-adding Mn²⁺ into the electrolyte, nevertheless faces the challenge of irreversible Mn²⁺ consumption results from the MnO₂ electrodeposition reaction (Mn²⁺  → MnO₂ ). This work proposes a "MOFs as the electrodeposition surface" strategy, rather than blocking it. The bismuth (III) pyridine-3,5-dicarboxylate (Bi-PYDC) is selected as the typical electrodeposition surface to regulate the deposition reaction from Mn²⁺ to MnO₂ . Because of the unique less hydrophilic and manganophilic nature of Bi-PYDC for Mn²⁺ , a moderate MnO₂ deposition rate is achieved, preventing the electrolyte from rapidly exhausting Mn²⁺ . Simultaneously, the intrinsic stability of deposited R-MnO₂ is enhanced by the slowly released Bi³⁺ from Bi-PYDC reservoir. Furthermore, Bi-PYDC shows the ability to accommodate H⁺ insertion/extraction. Benefiting from these merits, the cathode-free ZIB using Bi-PYDC as the electrodeposition surface for MnO₂ shows an outstanding cycle lifespan of more than 10 000 cycles at 1 mA cm^-2 . This electrode design may stimulate a new pathway for developing cathode free long-life rechargeable ZIBs.

Synthetic and structural comparisons of bismuth(iii) carboxylates synthesised under solvent-free and reflux conditions

Two synthetic approaches to the formation of bismuth(III) carboxylates have been explored and compared. Ph(3)Bi was reacted with a series of carboxylic acids (RCO(2)H) of varying pK(a) and functionality (R = PhCH[double bond, length as m-dash]CH, o-MeOC(6)H(4), m-MeOC(6)H(4), o-H(2)NC(6)H, o-O(2)NC(6)H(4), p-O(2)NC(6)H(4), 2-(C(5)H(4)N)) under reflux conditions in toluene and solvent-free. The thermochemical profiles of the solvent-free reactions were also studied by DSC-TGA. All reactions produced the tri-substituted bismuth carboxylates in comparable yields and purity with the exceptions of picolinic acid and p-nitrobenzoic acid. 2-Picolinic acid exclusively formed the di-substituted complex, [PhBi(2-(C(5)H(4)N)CO(2))(2)](4), by both methods, while p-nitrobenzoic acid gave the tri-substituted complex through reflux and the di-substituted complex under solvent-free conditions. Two of the complexes were structurally authenticated by single crystal X-ray diffraction: [PhBi(2-(C(5)H(4)N)CO(2))(2)](4) is tetrameric formed through five membered chelate rings involving the pyridyl N and O(-C) rather than the less stable carboxylate (-CO(2)) chelates, while [Bi(o-MeOC(6)H(4)CO(2))(3)](infinity), is a polymer in which dimeric units, constructed around two chelating and one unsymmetrical bridging carboxylate on each Bi centre, are then joined together through longer intermolecular Bi-O bridging bonds.

Crystal structure of a binuclear polymeric self-assembled lead(II) complex

A polymeric self-assembled complex [[Pb(pydc)(pydc-H2)(H2O)2]2]n is prepared from the complexation of a novel pyridine containing self-assembling system, LH2, [pyda-H2]2+[pydc]2- (pyda = 2,6-pyridindiamine and pydc-H2 = 2,6-pyridinedicarboxilic acid) and lead(II) nitrate in 84% yield. The characterization was performed using X-ray crystallography. The crystal system is triclinic with space group P1 and two molecules per unit cell. The unit cell dimensions are a = 6.913(2) A, b = 10.687(4) A and c = 11.182(4) A with alpha = 92.805(6) degrees, beta = 101.821(6) degrees and gamma = 95.688(6) degrees. The final R value is 0.0373 for 4633 reflections measured. This compound is a nine-coordinate binuclear complex with two metal fragments linked via the central four-membered Pb2O2 ring. The crystal also contains a neutral [pydc-H2] molecule, that form hydrogen and coordination bonds that dominate the crystal packing, by forming layers of molecules.

First anionic 1,10-phenanthroline-2,9-dicarboxylate containing metal complex obtained from a novel 1:1 proton-transfer compound: synthesis, characterization, crystal structure, and solution studies

The new 1,10-phenanthroline containing 1:1 proton-transfer compound LH(2), [pyda.H(2)](2+)[phendc](2-), was synthesized from the reaction of 2,6-pyridinediamine, pyda, and 1,10-phenanthroline-2,9-dicarboxylic acid, phendc.H(2), and characterized by elemental analysis, ES-Ms, IR, (1)H, (13)C NMR, and UV/vis spectroscopies. Subsequently, the first example of [phendc](2)(-) containing anionic complex [pyda.H](2)[Co(phendc)(2)].10H(2)O, was prepared, using the above novel proton-transfer compound, and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in the space group P2(1)/n of the monoclinic system with four molecules in a unit cell of dimensions a = 11.877(3) A, b = 31.473(9) A, c = 12.915(4) A, and beta = 116.223(5) degrees. The structure has been refined to a final value for the crystallographic R factor of 0.0524 based on 9021 observed independent reflections. The complexation reactions of pyda, phendc.H(2), and LH(2) with H(+) as well as LH(2) with Co(II) in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described. The results are presented in the form of distribution diagrams revealing the concentrations of individual complex species as a function of pH. The results revealed that, at a pH range of 5.2-6.2, the major complex species is [(pyda.H)](2)[Co(phendc)(2)], similar to the isolated crystalline complex.

Synthesis, characterization, and X-ray crystal structures of Co(II) and La(III) complexes of a pyridine containing self-assembling system and solution studies of the Co(II) complex

The complexes [pyda.H]2[Co(pydc)2]·H2O (I) and [pyda·H]2[La2(pydc)4(H2O)4].2H2O (II) were prepared from the complexation of a novel pyridine containing self-assembling system LH2, ([pyda·H2]2+[pydc]2–) (pyda = 2,6-pyridinediamine and pydc·H2 = 2,6-pyridinedicarboxylic acid), with cobalt(II) and lanthanum(III) salts in 82% and 74% yields, respectively. The characterizations were performed using elemental analysis, ESI mass spectroscopy as well as 1H and 13C solution NMR spectroscopy, and X-ray crystallography. The crystal systems I and II are monoclinic and triclinic with space groups P21/n and P[Formula: see text] respectively. Coordination number around each Co atom is six with distorted octahedral geometry, while coordination number around each La atom is nine with highly distorted tricapped trigonal prism geometry. The paramagnetic Co(II) and diamagnetic La(III) complexes show 1H NMR resonances of both anionic [pydc]2- and cationic counter ion [pyda·H]+ in DMSO-d6. The complexation reactions of the complex I in aqueous solution were investigated by potentiometric pH titrations and the equilibrium constants for all major complexes formed are described. The results are presented in the form of distribution diagrams revealing the concentrations of individual complex species as a function of pH. The results revealed that at a pH range 4.0–4.5 the major complex species is [(pyda·H)]2[Co(pydc)2].Key words: self-assembly, X-ray crystal structure, Co(II) complex, La(III) complex, 2,6- pyridinedicarboxylic acid, 2,6-pyridinediamine, hydrogen bonding.