Self-Assembly of Organostannoxanes: Formation of Gels in Aromatic Solvents

Abstract

Organostannoxane drums [n-BuSn(O)O2C-C6H4-4-OR]6 [R = −CH3 (1); −C9H19 (2); −C11H23 (3)] and [n-BuSn(O)O2C-C6H3-3,5-(OR)2]6 [R = −CH3 (4); −C9H19 (5)] were synthesized by the reaction of n-BuSn(O)(OH) with the corresponding carboxylic acid in a 1:1 stoichiometry. Analogous reactions involving [n-Bu2SnO]n in a 1:1 stoichiometry afforded the diorganostannoxane ladders {[n-Bu2SnO2C-C6H4-4-OR]2O}2 [R = −CH3 (6); −C9H19 (7); −C11H23 (8)] and {[n-Bu2SnO2C-C6H3-3,5-(OR)2]2O}2 [R = −CH3 (9) and −C9H19 (10)]. Compounds 1−10 could also be prepared by a solventless methodology, which involved grinding the reactants together in a mortar and pestle at room temperature. Compounds 1−10 exhibit gelation behavior in aromatic solvents. In contrast, in aliphatic solvents gelation behavior was not observed. Among the organostannoxanes reported here, 2, 3, 5, and 8 were found to be extremely efficient gelators based on their critical gelation concentration values. The microstructure of the organometallic gels, investigated by...