Thiomethyl Derivatives of Two Oligo(p-phenylene vinylenes) as New Aggregation-Induced Piezofluorochromic Emitters

Abstract

Two piezochromic fluorescent compounds are prepared by introducing thiomethyl substituents to the peripheralpositions of two related cyano oligo(p-phenylene vinylenes) (CN-OPV). The new derivatives, namely, 1,4-bis[2-cyano-2(4-thiomethylphenyl)ethenyl]benzene (TOPV1) and 1,4-bis(1-cyano-2-(4-thiomethylphenyl)ethenyl) benzene (TOPV2), are characterized by NMR, powder X-ray diffraction data (XRD) and differential scanning calorimetric (DSC) data. UV-Vis and fluorescence spectra are also measured. TOPV1 with the cyano groups farther away from the central aromatic ring is photoluminescent, and on application of pressure exhibits a more obvious color change and higher Stokes shift than those measured for TOPV2. We also observe piezochromic aggregation-induced emission (PAIE) for TOPV2, but TOPV1 does not exhibit any PAIE.