1,2‐Disubstituted 3,3,4,4,5,5‐Hexafluorocyclopentenes as Bent Light‐Emitting π‐Conjugated Luminophores

Herein, a series of 1,2-disubstituted 3,3,4,4,5,5-hexafluorocyclopentene derivatives is synthesized from the commercially available octafluorocyclopentene via addition-elimination reactions, and their photophysical properties are investigated in detail. 1,2-Bis[2-(4-alkoxyaryl)ethyn-1-yl]-3,3,4,4,5,5-hexafluorocyclopentene exhibits UV-absorption at 345 nm in CH2Cl2 and deep blue photoluminescence (PL). The PL properties of these derivatives, including color and maximum wavelength (lambda(PL)), are strongly affected by the electron-density distribution induced by the electronic characteristics of the alkoxy-substituents at the 4-position of the benzene ring, with more electron-donating substituents resulting in a larger shift of lambda(PL) to longer wavelengths. Note that the present light-emitting pi-conjugated luminophores also exhibit relatively strong PL in the crystalline state, where lambda(PL) shifts can be introduced by modulation of the terminal alkoxy-chain length, resulting in different PL colors from light-blue to orange.