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.

The study presents a rational synthesis of new dimethyltin carboxylates, Me2Sn­(H2btec) (1), Me2Sn­(btec)0.5(2), [Me2Sn­(H2O)2(btec)0.5]·H2O (3), and [{Me2SnOSn­(OH)­Me2}­(Me2SnOH)­(btec)0.5]·H2O (4), derived from tetratopic 1,2,4,5-benzenetetracarboxylic acid (H4btec). The method relies upon hydrothermal reaction (130 °C, 72 h) of dimethyltin dichloride and H4btec under optimized pH (2 < pH < 8) conditions that allow control over dimethyltin speciation in aqueous medium as well as degree of deprotonation of the tetrafuntional carboxylic acid. The formation of a three-dimensional assembly in 1 is assisted by the bridging bidentate (μ2) mode of the carboxylate and O–H···O hydrogen bonds involving −COOH groups. The structure represents a unique example of the diorganotin framework derived from a partially deprotonated polyfuntional carboxylic acid. The structure of 2 adopts a three-dimensional motif wherein each pair of μ2-carboxylate groups (designated by C1 and C4) of the tetraanionic ligand form different spatial arrangements. For 3, the formation of one-dimensional motif with eight-coordinated tin atoms is assisted by the anisobidentate character of the carboxylate groups. The structure of 4 includes linear chains comprised of [Me2Sn­(μ2–OH)]2 and the carboxylate ligand which extend to a layered motif with symmetrically substituted ladder-like distannoxanes acting as linkers. The underlying nets of 1, 2, and 4 exhibit sqc11, scu­(sqc170), and sql topologies, respectively. Notably, these assemblies are extremely robust and show no sign of degradation upon exposure to neutral as well as weakly acidic/basic aqueous medium for 7 days.

Hydrothermal reaction of trimethyltin chloride with 1,2,4,5‐benzenetetracarboxylic acid (H4L1), 2,3‐pyridinedicarboxylic acid (H2L2) or 1,4,5,8‐naphthalenetetracarboxylic acid 4,5‐anhydride (H2L3) under optimized pH (5–6) and temperature (130 °C) results in the isolation of new dicarboxylatotetramethyldistannoxane‐based two‐/three‐dimensional coordination assemblies, [{Me2Sn(L1)0.25}2O] (1, 2 as supramolecular isomers), [{Me2Sn(L2)0.5}2O] (3) and [{Me2Sn(L3)0.5}2O] (4). The reaction in each case proceeds with selective cleavage of Sn–C bond. Analogous reaction of trimethyltin chloride with H4L1 at 100 °C affords [Me3Sn(L1)0.25] (5). The supramolecular coordination isomers 1 and 2 with cds and lvt network topologies, respectively are the first representatives among the distannoxane family; the latter confers large solvent accessible voids of 37 % per unit cell. The formation of ladder distannoxane, [{Me2Sn(O2C)}2O]2 as a common structural motif in 1, 3 and 4 is a manifestation of a predefined geometry of the inorganic secondary building unit (SBU) and follows the benchmark of reticular chemistry approach. The coordination assembly, 5 adopts an eight‐connected uninodal net that belongs to bcu topology. These are thermally stable up to 250–400 °C and retain their crystallinity even after exposure to hydrothermal treatment for 24 h.

The study presents the synthesis and structural aspects of a new family of dimethyltin carboxylates, [(Me2Sn)2(btec)(bipy)(H2O)] ⋅ 4H2O (1), [Me2Sn(btec)0.5(bipy)]2 ⋅ H2O (2), [Me2Sn(btec)0.5(bipy)] ⋅ 3H2O ⋅ 0.5bipy (3) and [Me2Sn(btec)0.5(phen)] (4) derived from 1,2,4,5‐benzenetetracarboxylic acid (H4btec). The structure in each case adopts a one‐dimensional motif featuring ditin macrocycles with 2,2'‐bipyridine (bipy) or 1,10‐phenanthroline (phen) acting as the chelating ligand. For 1, the lattice water molecules in association with the framework form infinite T4(0)A(1) water chains. The organic hydrate, bipy ⋅ 6H2O in 3 adopts a layered structure comprising T4(2)6(2) water tapes and trans‐bipy. Dehydration of 2 to 2 a results in crystal structure transformation from centrosymmetric P21/c (in 2) to chiral P212121 space group and reveals conformational changes in the ditin macrocycles from chair to boat form. The reversibility of this transformation has been supported by TGA, PXRD, and single‐crystal X‐ray studies.

The Front Cover shows the synthesis of one‐dimensional ladder‐like structures of dimethyltin carboxylates in an aqueous medium and highlights the role of chelating 2,2'‐bipyridine to control the dimensionality in the presence of 1,2,4,5‐benzenetetracarboxylate ligand. The structures reveal supramolecular assemblies formed by the inclusion of infinite water tapes [T4(0)A1] or the organic hydrate (bipy⋅6H2O). The study is a manifestation of reversible single crystal to single crystal structural transformation from P21/c to P212121 upon dehydration with conformational changes in the macrocycles. More information can be found in the Research Article by R. Shankar and co‐workers.