Studies on the Genesis and Proton Conductivity of Imidazole-Based Linear and Open-Framework Zinc Phosphites

Three new zinc phosphites, [HIm]₂[Zn₃(HPO₃)₄] (1), [Zn₂(HPO₃)₂Im₂] (2), and [Zn(HPO₃)Im] (3) (Im = imidazole), have been synthesized from the hydro/solvothermal reaction of zinc acetate, dimethyl phosphite, and imidazole by varying the temperature and solvent of the reaction medium. The structure of 1 is built from vertex-sharing of four HPO₃-capped Zn₃P₃ units and adopts an open framework with 12-ring channels stabilized by HIm cations via N-H···O hydrogen bonds. For 2, the inorganic skeleton is comprised of alternating ZnO₄ and HPO₃ tetrahedra, while the coordinatively associated ZnN₂O₂ fragments occupy the 12-ring hexagonal channels. Compound 3 adopts a ladder-type one-dimensional structure and exhibits N-H···O hydrogen-bonding interactions to afford a supramolecular assembly. A plausible rationale on the genesis of 1-3 has been put forth by reacting the preformed inorganic zinc phosphites Zn{OP(O)(OMe)H}₂ or [Zn₂(HPO₃)₂(H₂O)₄]·H₂O with imidazole as the structure-directing ligand. Alternating-current impedance measurements reveal that 1 and 3 exhibit proton conductivities on the order of 10^-3-10^-4 S cm^-1 between 25 and 100 °C under 35 and 77% relative humidity in repeated impedance cycles (E_a = 0.22-0.35 eV). On the contrary, the conduction property is completely impaired in 2 under similar conditions.

Solvent-free synthesis and room temperature proton conductivity of new cobalt phosphite–oxalates

Two new cobalt phosphite–oxalates (1 and 2) have been synthesized under solvent-free conditions. Compound 2 possesses room temperature proton conductivity.

Concise template syntheses of gallium phosphates driven by in situ direct alkylation of aliphatic and aromatic precursors by methanol

In situ template design and generation strategy is applied to synthesize microporous materials. We report five new organically templated gallium phosphates with different structures varying from 1D chain to 2D layer and 3D framework.

Synthesis, characterization and selective de-esterification of diorganotinbis(O-methylphosphite)s

A one-pot reaction between di-n-butyl/diethyl/dimethyltin dichloride and dimethylphosphite (MeO)2P(O)H in a solvent free medium (120 °C, 18 h) proceeds smoothly to yield the corresponding diorganotinbis(O-methylphosphite)s, [R2Sn(OP(O)(OMe)H)2]n [R = n-Bu (1), Et (2), Me (3)]. The identity of 1-3 has been established by IR, multinuclear ((1)H, (13)C, (31)P, (119)Sn) NMR, powder X-ray diffraction (PXRD) and X-ray crystallography. The coordination framework in each case adopts a one-dimensional structural motif comprising an infinite array of eight-membered [Sn-O-P-O]2 cyclic rings, with the phosphite ligands acting in a bridging bidentate mode. The structures are extended to two- (for 1) and three-dimensional (for 2, 3) assemblies by virtue of C-H···O hydrogen bonding interactions. The stability and bulk properties of 1-3 have been investigated upon exposure to humid laboratory conditions using (1)H NMR, PXRD and SEM studies. The results conform to a unique chemical modification of 1-3 involving selective de-esterification of P-OMe bonds and the formation of corresponding diorganotinbis(phosphite)s, [R2Sn(OP(O)(OH)H)2]n (1a-3a), as insoluble solids. The results obtained from impedance studies (σ = 10(-4)-10(-6) S cm(-1); E(a) = 0.33-0.42 eV) reveal potential application of 1a-3a as proton conducting materials.