Novel Phenothiazine‐5‐oxide Based Push‐Pull Molecules: Synthesis and Fine‐Tuning of Electronic, Optical and Thermal Properties

Abstract

AbstractA series of eight acceptor‐donor‐acceptor (A‐D‐A) type small push‐pull compounds based on non‐planar phenothiazine‐5‐oxide as central donor building block end‐capped with different accepting groups were synthesized and characterized. These A‐D‐A systems were evaluated for their electronic, optical and thermal properties by density functional theory (DFT), UV‐Vis, fluorescence, thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) methods. Single crystal X‐ray diffraction (XRD) and DFT studies revealed near‐planar geometry for N‐aryl substituted over N‐alkyl substituted phenothiazine moiety in these A‐D‐A molecules leading to better orbital overlap and stabilization through intramolecular charge transfer (ICT) transition. The HOMO‐LUMO energy gap was observed in the range of 3.70‐4.28 eV. Photoluminescence (PL) studies showed triple as well as dual fluorescence with red‐shifted spectra. Also, TGA and DTA studies indicated moderate to good thermal stability with decomposition temperature (Td) in the range of 159–302 °C.