Abstract
A new series of push-pull chromophores (1–6) with ferrocene and methoxyphenyl donors and π-acceptor groups were synthesized and characterized. The chromophores (1–3) [Fc-C = C(CN)-(C6H4)-(C6H3)-R {R = H (1), OCH3 (2), CF3 (3)}] and D-D’-π-A (4–6), [Fc-(OCH3-C6H4)-C = CH=CN-(C6H4)-(C6H3)-R {R = H (4), OCH3 (5), CF3 (6)}] were studied for their photophysical and nonlinear optical (NLO) properties. Single-crystal X-ray diffraction studies confirmed the crystal structures of selected chromophores 1, 3, 4, and 6, showing various non-covalent interactions such as H-bonding and C-H⋅⋅⋅⋅⋅π interactions. The second-order nonlinear optical (NLO) response of chromophore 6 shows significantly enhanced second-harmonic generation (SHG) efficiency, approximately 2.9 times higher than that of standard potassium dihydrogen phosphate (KDP), due to the extended π-conjugation results in deviation of chromophores from planarity, which prevents antiparallel alignment in the bulk. To gain deeper insight into structure-property relationships, bond length alternation (BLA) values were evaluated based on BLA, correlating with NLO performance. Furthermore, density functional theory (DFT) calculations at the B3LYP/6–31 + G** level included both static and dynamic energy-dependent hyperpolarizabilities, showing good agreement with experimental optical and NLO results.
Data availability
The datasets used and/or analysed during the current study are available from corresponding author on reasonable request.
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Acknowledgements
The authors gratefully acknowledge the support from the Science and Engineering Research Board, Department of Science and Technology, Government of India, under the Core Research Grant (CRG/2021/004067). Additionally, they express sincere appreciation for the instrumental facilities provided by VIT-SIF. Our heartfelt thanks go to Prof. P. K. Das from the Department of Inorganic and Physical Chemistry at the Indian Institute of Science, Bangalore, for performing the SHG measurements.
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Open access funding provided by Vellore Institute of Technology. Open access funding provided by Vellore Institute of Technology, Vellore.
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(A) Vadakkalur Sampath Chithra: Data curation, Investigation, Synthesis, Methodology, Software, DFT calculations, and Writing—original draft. (B) Selvam Prabu: Methodology, Software, DFT calculations. (C) P P Sanak Archana: Synthesis. (D) Nallasamy Palanisami: Conceptualization, Formal analysis, Funding acquisition, Supervision, writing—review & editing.
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Chithra, V.S., Prabu, S., Archana, P.P.S. et al. Exploring the impact of substituents and π-conjugation on structural, optical and nonlinear optical studies in ferrocene-appended D-π-A and D-D’-π-A chromophores. Sci Rep (2026). https://doi.org/10.1038/s41598-026-37577-w
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DOI: https://doi.org/10.1038/s41598-026-37577-w
