Diol Struts Stabilize the Structure of a 3D Hydrogen-Bonded Framework with Large Cavities: Inclusion of Solvated Nile Red in the Solid State

Abstract

Three-dimensional hydrogen-bonded frameworks (3D HBFs) based on organotin macrocycles were obtained by self-assembly of 2,5-pyridinedicarboxylic acid and di-n-dibutyltin(IV) oxide in alcohol-chloroform mixtures and subsequently stabilized by substituting monoalcohol molecules within the network by diols (1,4-butanediol and 1,5-pentanediol). The C–C bond linkages in the diols converted the solvate molecules into struts, stabilizing the noncovalent network and providing air-stable HBFs with large spherical hydrophobic cavities. Inclusion of Nile Red proved molecular recognition properties and gave fluorescent crystalline materials. The inclusion compound studied herein experiences a visual change of the fluorescence emission properties in the presence of solvent vapors having different polarity, indicating its potential for the development of sensors for the detection of volatile and gaseous substances.