Synthesis of Donor-Acceptor(D-A)Typed Phenylcyclooctatetrathio-phenes and Their Performances on Aggregation Induced Emission and High Pressure Luminescence
The saddle-shaped cyclooctatetrathiophene(COTh)is an interesting aggregation induced emission(AIE)mole-cule.In this work,the strong electron withdrawing group(CN)and the strong electron donating group(OMe)are introduced into the ortho,meta and para positions of benzene ring,reacting with COTh unit through Suzuki reaction to construct six donor-acceptor(D-A)typed substituted phenyl Ar-COTh compounds.The single crystal structure ofp-OMe-Ph-COTh shows multiple intermolecular interactions,such as S…C,C…O and O…H interactions among molecules.These D-A typed Ar-COThs exhibit significant AIE luminescence properties,which are mainly attributed to the intramolecular through space conjugation(ITSC)of COTh in excited state.The weak correlation between the emission peak and the substituent effect is observed.The fluorescence quantum yields of Ar-COThs in solid-state luminescence are higher than that of AIE state.Under high pressure,the emission peak of p-CN-Ph-COTh containing strong electron withdrawing group(CN)showed strong bath-ochromic shift from 531 nm to 634 nm with a big difference of 103 nm under the external pressure change from 0.00 to 8.86 GPa;However,the emission peak of p-OMe-Ph-COTh containing electron donating group(OMe)gave the only change of 29 nm under the pressure change from 0.00 to 12.0 GPa,demonstrating significant substituent and piezochromic effects.