Push–pull heterocycles and beyond: recent developments in absorption, emission, and ICT properties
Manel Essid, Ehsan Ullah Mughal
Abstract
Heterocyclic scaffolds represent a cornerstone in the development of advanced organic materials owing to their tunable electronic structures and diverse photophysical properties. Recent studies have demonstrated significant progress in the design and synthesis of heterocyclic chromophores, particularly focusing on their absorption and emission behaviors, donor-acceptor interactions, intramolecular charge transfer (ICT), and solvent-dependent spectral shifts. In this review, we present for the first time a comprehensive summary of the literature reported during 2024-2025, covering a wide range of systems including indole-coumarins, 3-cyano-2-pyridones, tetracyanobuta-1,3-diene (TCBD) derivatives, highly annulated boron-dipyrromethenes (BODIPYs) and pyrimidine-based boron complexes. Key discussions emphasize how structural modifications, solvent polarity, and push-pull effects influence band gaps, bathochromic and hypsochromic shifts, fluorescence quantum yields, and near-infrared (NIR) emission properties. By correlating structure-property relationships, this review provides important insights into molecular design strategies and highlights the potential of heterocyclic chromophores as promising candidates for next-generation optoelectronic, sensing, and photonic applications.