Synthesis of New 2D-π-2A Chromophores Based on Tetraphenyl Fulvene and Investigation of Their Optical Properties

Abstract

Emitting organic molecules can find application in Light-Emitting Diodes and as Biosensors. The new generation of organic emitters are full conjugated molecules exhibiting conformational freedom that can gain emission intensity when accumulate. We synthesized new tetraphenyl fulvene (TPF) derivatives by connecting the phenyl rings 3 and 4 with electron donor groups and the fulvene carbon 6 with two electron-withdrawing groups. We analyzed the optical properties, UV–vis absorption, and emission in different solvents with different polarities. The compound with π-donor thiophene and π-acceptor methyl malonate, named 5mT, displays the highest emission intensity compared to unsubstituted TPF, the compounds with a weak electron π-donor group on phenyl rings 3 and 4, and the weak π-withdrawing group on carbon 6 of the fulvene core. The same compound exhibits emission frequencies in solutions that vary from 435 to 495 nm in the different solvents, while the emission frequency is 435 nm independently of the solvent for the other TPF derivatives. We demonstrated that D-π-A TPF derivatives with high dipolar moments display a fluorescence that is strongly influenced by conformational status and intermolecular interactions.

Keywords

• tetraphenylfulvenes derivatives
• 2D-π-2A molecules
• solvent-dependent emission frequency