C 3-Symmetric star shaped donor-acceptor truxenes: Synthesis and photophysical, electrochemical and computational studies

Abstract

This manuscript reports the design and synthesis of C3-symmetric star shaped donor and acceptor substituted truxenes 6, 7, 10 and 11 using Pd-catalyzed Sonogashira cross-coupling and [2+2] cycloaddition-retroelectrocyclization reactions. Their photophysical, electrochemical and computational studies were explored, which indicate strong donor-acceptor interactions and effective tuning of the HOMO-LUMO gap. The computational studies reveal that the TCNE and TCNQ substituted truxenes 10 and 11 exhibit lower HOMO-LUMO gaps compared to truxenes 6 and 7. The reaction pathway of [2+2] cycloaddition-retroelectrocyclization was studied using computational calculations, which reveal that the donor substituted truxene 7 is favourable for cycloaddition-retroelectrocyclization reactions, whereas acceptor substituted truxene 6 is not favourable. © 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.