Unveiling the multifaceted nature of terpyridine-based metal complexes: a synergistic study of their photophysical and electrochemical behavior with computational insights

This manuscript provides a comprehensive overview of the synthesis, characterization, and photophysical and electrochemical properties of terpyridine-based metal complexes (C₁-C₂₀). The synthesis of these terpyridine (TPY) complexes involves the coordination of TPY ligands (L₁-L₁₁) with transition metal ions, leading to a variety of novel structural and electronic configurations. The characterization of TPY ligands and their complexes is carried out using various techniques, including UV-Vis spectroscopy, NMR, FTIR and mass spectrometry. To the best of our knowledge, for the first time, we comprehensively investigate the photophysical, solvatochromic, electrochemical, and computational properties of an extensive series of TPY-based metal complexes (C₁-C₂₀) within a single framework. The solvatochromic behavior of the synthesized complexes (C₁-C₂₀) is explored, revealing their sensitivity to solvent polarity, which is a key factor influencing their photophysical properties. The TPY-based complexes (C₁-C₂₀) exhibited solvent-dependent fluorescence behavior, with distinct ILCT and MLCT mechanisms, and enhanced fluorescence in specific solvents, particularly for Zn(ii) and Cu(ii) complexes. The absorption and emission characteristics of the complexes are studied in dilute solutions to explore their structure-property relationships. Additionally, the electrochemical properties of the TPY-based metal complexes (C₁-C₂₀) are investigated, highlighting their redox activity and potential for use in energy storage and conversion applications. Density functional theory (DFT) calculations are employed to provide detailed insights into the electronic structure and reactivity of these complexes, supporting the experimental observations. The correlation of electronic band gaps with photophysical and electrochemical behaviors showed compounds as promising candidates with efficient charge transfer and strong fluorescence. The integrated analyses reveal the exceptional potential of this scaffold for advanced materials applications, highlighting its versatility and significance in cutting-edge research.