Synthesis, crystal structure and supramolecular self-assembly of tetraphenylethylene subunit appended isoindigo derivatives

Abstract

In this work, we design and synthesis donor-acceptor-donor based two new chromophores containing isoindigo (IN) as an acceptor core functionalised with two donor tetraphenylethylene (TPE) on the periphery one without thiophene spacer (Coded as: TPE-IN1) another derivative with thiophene as a spacer (Coded as: TPE-IN12. For the synthesis of both the derivatives Suzuki cross-coupling reaction was employed. Fluorescence emission spectral proeprties of TPE-IN1 and TPE-IN2 was investigated in mixture of chloroform (CHCl sub(3)):methylcyclohexane (MCH) and tetrahydrofuran (THF):water (H sub(2) O). The results shows an aggregation-caused quenching (ACQ) effect, which may be due to energy/electron transfer from TPE to IN core, as TPE is typically aggregation induced emission (AIE)-active chromophore. The self-assembled/aggregated structures in solution was characterized by means of fluorescence lifetime and dynamic light scattering (DLS) measurement. The crystalline morphology on the silicon wafer was investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Furthermore, our study of supramolecular self-assembly of TPE-IN1 and TPE-IN2 in THF:H sub(2) O (10:90 perent) and CHCl sub(3) :MCH (10:90 percent) solvent mixes shows various superstructures. Typically, TPE-IN1 displayed interesting hexagonal rod like morphology in THF:H sub(2) O mixture, where as TPE-IN2 showed self-assembled crystalline fibrous morphological micro and nanostructures via the solvophobic effect.