Facile synthesis of anthracene-based derivatives via a magnetically retrievable Fe3O4@SiO2 immobilized selenoether functionalised NHC-Pd(II) heterogenous catalyst: Photophysical, electrochemical and DFT studies of novel 9,10-anthracene based derivatives

Abstract

A series of anthracene-based derivatives, which are promising candidates for Organic light-emitting diode (OLEDs) applications, have been synthesized through the Suzuki Miyuara cross-coupling reaction of dibromo anthracene and phenylboronic acids derivatives. A magnetically separable heterogeneous catalyst Fe3O4@SiO2@NHC^SePh-Pd(II) was used, and the coupling reaction was investigated under aerobic conditions using water as a green solvent. A very mild approach for the arylation of the 9,10-dibromo anthracene molecules was adopted to harvest a series of highly conjugated anthracene derivatives. The catalyst was reused for up to seven catalytic cycles without much loss in catalytic efficiency. The 55% transformation in the seventh catalytic cycle indicates the catalyst's robustness and high catalytic potential. Necessary photophysical studies were conducted for selected synthesized anthracene-based derivatives, which includes the absorption, emission and cyclic voltammetric studies. Moreover, the thermogravimetric analysis (TGA) was also conducted to check the thermal stability of the compounds. Finally, a Density Functional Theory (DFT) study was conducted, and it revealed that comparing two anthracene derivatives, the Highest occupied molecular orbital (HOMO) and Least unoccupied molecular orbital (LUMO) energy levels, as well as the HOMO-LUMO gap (HLG), differ, with 9-([1,1′-biphenyl]-4-yl)-10-(4-fluorophenyl) anthracene exhibiting a relatively large HLG. The HOMO is localised along the molecule's main axis, while the LUMO is more delocalised on atoms.