The Synthesis and Anion Recognition Property of Symmetrical Chemosensors Involving Thiourea Groups: Theory and Experiments.

Abstract

Four symmetrical compounds incorporating urea or thiourea moieties combined with anthracene or nitrobenzene units were synthesized and evaluated for anion recognition. Among these, N,N'-di((anthracen-9-yl)-methylene)thio-carbonohydrazide demonstrated selective and sensitive binding toward acetate ions, with negligible interference from competing anions such as F⁻, H₂PO₄⁻, Cl⁻, Br⁻, and I⁻. The host-guest interaction was attributed to multiple hydrogen bonds arising from conformational complementarity and elevated basicity. Computational analysis confirmed the presence of intramolecular hydrogen bonds that enhance anion binding capacity. Frontier molecular orbital analysis was employed to account for the observed red-shift during host-guest interactions. These thiourea-anthracene derivatives show potential as chemosensors for acetate ion detection in environmental and pharmaceutical contexts.

Mechanism

Acetate ion binding occurs via multiple hydrogen bonds driven by conformational complementarity and high basicity; intramolecular hydrogen bonds further strengthen binding affinity, while frontier molecular orbital interactions account for the observed spectral red-shift.