ORIGINAL RESEARCH article
Front. Chem.
Sec. Solid State Chemistry
Thermally Tunable Naphthalene Diimide Solvates Enabling Selective Sensing, Reversible Photochromism, and Anti-counterfeiting Application
Loveleen Kaur 1
Kawal Preet 1
Anasuya Mishra 2
BIGYAN RANJAN JALI 3
Deepak B Salunke 4
Subash Sahoo 1
1. Panjab University, Chandigarh, India
2. Government Autonomous College, Angul, India
3. Veer Surendra Sai Institute of Medical Sciences and Research, Burla, India
4. National Institute of Pharmaceutical Education and Research, Sahibzada Ajit Singh Nagar, India
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Abstract
Recent studies have highlighted the potential of naphthalene diimide (NDI)-based molecules due to their stimuli-responsive and optical characteristics. In this work, we report two naphthalene diimide (NDI)-based solvates, designated as NDI-1 and NDI-2, were successfully synthesized from 4-aminopyridine and 1,4,5,8-naphthalene tetracarboxylic dianhydride (NDA) and comprehensively characterized using FT-IR, TGA, UV–Vis, fluorescence spectroscopy, PXRD, ¹H NMR, single-crystal X-ray diffraction, and Hirshfeld surface analysis. Despite being solvates of each other, NDI-1 and NDI-2 exhibit distinct solvatochromic propertes in DMF solution, as demonstrated by their unique UV–Vis absorption and fluorescence responses. Notably, the compounds display exceptional selectivity toward Hg²⁺ ions in DMF, outperforming a range of competing metal ions and producing characteristic optical changes. Furthermore, both solvates undergo reversible photochromic transformations upon exposure to UV light (365 nm), sunlight, and tungsten light, with the fastest switching under UV irradiation. These light-induced color changes gradually revert after removal of the stimulus, and similar reversible behavior is retained in polymer-embedded films (PVDF@NDI-1). Overall, this study provides a valuable strategy for designing multifunctional NDI-based materials, addressing the limited availability of conjugated systems that simultaneously exhibit multiple responsive properties and offering promising prospects for secure data storage and anti-counterfeiting technologies.
Summary
Keywords
Anti-counterfeiting, Chemo-sensor, Naphthalene diimides, Photochromism, Solvatochromism
Received
04 December 2025
Accepted
06 January 2026
Copyright
© 2026 Kaur, Preet, Mishra, JALI, Salunke and Sahoo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Subash Sahoo
Disclaimer
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