Aseries of five novel dyes based on indolo[2,3-b]quinoxaline skeleton, derived from anthraquinone, have been synthesized through cyclo-condensation reaction in good yield. The photophysical, electrochemical and thermal properties along with computed HOMO-LUMO energy levels were studied for the synthesizedcompounds. Their absorption and photoluminescence properties were investigated in various solvents and in neat solid film and found to possess characteristic electronic absorption and emission spectra which stronglydepend on the nature of solvents used. Compounds show intramolecular charge transfer transitions (ICT) in the range of 501–561 nm with high molar absorption coefficient (ε). These indoloquinoxaline derivatives emit in the range of 580–648 nm in solutions and 672–700 nm (red region) in neat solid films. Electrochemical data indicate that the dyes possess relatively low–lying LUMO levels in the range −3.29 to −3.43 eV. The thermal stability observed for these compounds suggests their use under ambient conditions. The in–built donor– acceptor architecture and HOMO–LUMO energies were further rationalized using DFT calculations. This study suggests that these compounds have potential to be used as n–type materials for optoelectronic devices.

A series of five new donor–acceptor molecules based on imidazo-anthraquinone-amines have been synthesized and characterized. The structure-property relationship in these molecules is systematically examined by absorption-emission spectroscopy, cyclic voltammetry and theoretical studies. Optical properties of these molecules have been studied in solvents of varying polarity as well as in neat solid film and found to be affected by the nature of triarylamine substituent with broad absorption windows, strong charge transfer transitions(425–502 nm), high molar extinction coefficients and emission in green light (500–568 nm). Electrochemical data indicated that the dyes possess relatively low-lying LUMO values (−3.18 to −3.42 eV) while TGA studies revealed good thermal stability. The donor-acceptor architecture and HOMO–LUMO energies were further rationalized using DFT calculations. Experimental studies along with theoretical calculations suggest that these compounds have potential to be used as n-type materials in optoelectronic devices.

Here, pyridopyrazino[2,3-b]indole based D–A assembly was designed and synthesized with modulation of various electron-donating/withdrawing substituent and characterized by various spectroscopic methods. Pyridopyrazino[2,3-b]indole derivatives show inbuilt intramolecular charge transfer (ICT) transitionwhich established D–A building in molecules and induces blue-green emission in the solution state. However, solid-state emission characteristics explore the emission property of some molecules towards aggregationinducedemission (AIE) effect which leads to the formation of emissive nano aggregates in THF/H₂O mixture. Alteration of substituent on pyridopyrazino[2,3-b]indole segment effectively tune electrochemical property and resulting LUMO energy level was found to be comparable with reported electron transporting/ntypematerials. These properties and good thermal stability indicate that molecules have the potential to be used as solid-state emitter and n-type materials in optoelectronic devices.