Silver-π Interaction: A Diverse Approach to Hybrid Material and Its Efficacy in Electrocatalytic Reduction of Nitrate to Ammonia.

Inspired by the intriguing nature of the metal-π interaction in organometallic chemistry, a novel 1D hybrid material has been designed. Herein, a functionalized tellurium allyl macrocycle (TAM) acts as a molecular building block and is knit together via silver-π interaction to obtain Ag-TAM. Ag is coordinated to two allyl groups and a phenyl ring in η2 mode. Instead of the conventional polymerization strategy, a metal-π interaction is employed to interlink macrocycles. TAM and Ag-TAM showed electrocatalytic capability for the conversion of nitrate to ammonia. Ag-TAM showed an NH3 yield rate 2-fold greater than TAM with a high faradaic efficiency of 94.6% with good durability, proving that interlinking of macrocycles via metal-π interaction improves the catalytic activity. Detailed periodic density functional theory (DFT) calculations unveil novel mechanistic insights, suggesting cooperative catalysis between neighboring Ag sites and contributing to the enhanced efficiency.

Electrocatalytic hydrogen evolution mediated by an organotelluroxane macrocycle stabilized through secondary interactions.

A discrete liphophilic organotelluroxane macrocycle has been found to catalyse the hydrogen evolution reaction (HER) by proton reduction efficiently. The macrocycle is synthesized via chloride abstraction from bis(p-methoxyphenyl) tellurium dichloride (p-MeOC6H5)2TeCl2 (1) by silver salts AgMX4 (MX4 = BF4-, and ClO4-) resulting in in situ generated di-cationic tetraorganoditelluroxane units; two such units are held together by two weak anions µ2-MX4, bridging to form 12-membered di-cationic macrocycles [((p-MeO-C6H4)2Te)2(µ-O)(µ2-F2BF2)2]2+ (2) and [((p-MeO-C6H4)2Te)2(µ-O)(µ2-O2ClO2)2]2+ (3) stabilized via Te-(µ2-BF4/ClO4), with secondary interactions. The charge is balanced by the presence of two more anions, one above and another below the plane of the macrocycle. Similar reaction at higher temperatures leads to the formation of telluronium salts R3TeX [X = BF4- (4), ClO4- (5)] as a major product. The BF4- anion containing macrocycle and telluronium salt were monitored using 19F NMR. HRMS confirmed the structural stability of all the compounds in the solution state. The organotelluroxane macrocycle 2 has been found to act as an efficient electrocatalyst for proton reduction in an organic medium in the presence of p-toluene sulfonic acid as a protic source.

Tunable bandgaps in self-assembled transition metal-incorporated heterometallic M2Sb4 (M = V, Mn, Co, Ni, and Cu) oxo clusters.

This paper investigates the reactivity and optical properties of transition metal-incorporated organoantimony(V) clusters prepared by a solvothermal route. The detailed structural characterization of novel heterometallic M2Sb4 oxo clusters is reported herein. Single crystal X-ray diffraction revealed the formation of hexanuclear organoantimony(V) based oxo clusters [(p-ClC6H4Sb)4V2(O)2(µ3-O)2(µ2-O)2(t-BuPO3)4(µ2-OCH3)4] (1), [M2(p-iPr-C6H4Sb)4(µ3-O)2(µ2-O)2(µ2-OCH3)4(t-BuPO3)4(py)2]·xCH3OH, where M = Mn, x = 2 (2), Co, x = 1 (3), Ni, x = 2 (4) and Cu, x = 2 (5). The magnetic behaviour of the clusters was probed by magnetic susceptibility measurements. Optical absorption studies showed that bandgap reduction can be achieved by incorporating an appropriate transition metal into the homometallic Sb6 oxo cluster.

Stibonic acids and related stibonate-phosphonate clusters: Synthesis, characterization and bioactivity evaluation.

The reaction of 4-(azobenzene)phenylstibonic acid with t-butylphosphonic acid led to the isolation of the tetranuclear oxo-hydroxo antimony cluster of formulae [(4-azobenzene-C6H4Sb)4(OH)4(tBuPO3)6] (C1). The reaction of (p-t-butyl phenyl stibonic acid with phenyl phosphonic acid resulted in the isolation of complex with formulae [(p-t-BuC6H4Sb)4(O)2(PhPO3)4(PhPO3H)4] (C2). Based upon the initial results from docking studies, parent stibonic acids, t-butyl-phenylstibonic acid, p-isopropylphenylstibonic acid, 4-azobenzenephenylstibonic acid, and the derived tetranuclear organoantimonate-phosphonate clusters were screened against different cancer cell lines, various Gram-positive and Gram-Negative bacteria and mycobacteria for possible bioactivity profile.