Aggregation-Induced Emission and Pressure-dependent Fluorescence of Aryl Cyclooctatetrathiophenes

Abstract As a nonaromatic cyclooctatetraene (COT) derivative, the rotor-free structural COTh may show interesting aggregation induced emission (AIE) phenomenon via conformation inversion of aromaticity. In this work, we have made a series of Ar-COThs by arylation of COTh via Suzuki reactions with Ar–B(OH)2, studied on their photoluminescence (PL) spectra in rigid solution and found a long wavelength emission peaked at 498 nm, which was proposed as a luminescence from the intramolecular through-space conjugation (ITSC) of COTh. Ar-COThs exhibit typical AIE phenomena in THF-H2O mixture based on luminophore COTh without effect of aryl substitution. The pressure-dependent fluorescent spectra of Ar-COThs in solid show remarkable effect of aryl substitution, resulting in bathochromic-shift and dimmer of emissions due to both ITSC of COTh and strong intermolecular interactions of Ar-COThs compressed under external pressure, which were supported by crystal structures and theoretical calculations.