A novel salicylaldehyde Schiff-base-functionalized 1,8-naphthalimide luminophore with controllable aggregation/solid/film fluorescence and reversible acid/base stimuli-responsive film fluorescence

IF 4 2区化学 Q2 CHEMISTRY, PHYSICAL Journal of Molecular Structure Pub Date : 2025-02-27 DOI:10.1016/j.molstruc.2025.141888

Mingguang Zhu , Jinghui Zeng , Xinyu Ye , Jiali Hu , Yuanbin Wu , Meihui Chen , Donghong Xie , Huihua Gong , Zhenye Wang , Liu Yang , Yaohui You

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Abstract

In the quest to engineer multifunctional fluorescent materials, 1,8-naphthalimide (NPI) and salicylaldehyde Schiff base molecules were considered as the promising fluorophores because of their fascinating vistas. Herein, from 1,8-naphthalic anhydride precursor, a novel salicylaldehyde Schiff-base-functionalized 1,8-naphthalimide (NPI) luminophore, where NPI core and salicylaldehyde Schiff base were judiciously integrated through a flexible methylene spacer, was elaborately designed and successfully synthesized in a high yield of 90 %. The structure-property relationship was meticulously lucubrated by comparing the photophysical properties of it and its analogues. Mainly, it enjoyed excited-state intramolecular proton transfer (ESIPT) process upon photoexcitation in solution state. Interestingly, it showed the vividly fluorochromic behaviours at the unimolecular level in the aggregation/solid/film states. Specifically, it exhibited multiple self-assembly stages in the proportionally mixed solutions of THF/H₂O with different water fractions (f_w), accompanying fluorescence transitions from aggregation-induced emission (AIE)+ESIPT-based emission to J-type aggregation-induced emission to H-type aggregation caused quenching. Moreover, its film fabricated by casting EtOH solution (10⁻⁵ M) onto the glass slide displayed thickness-dependent fluorescence colour changes and reversible acid/base stimuli-responsive fluorescence. Furthermore, its solid obtained by crystallization in the EtOH/water (1/1, v/v) mixtures (approximately 10⁻² M) exhibited the reversible mechanochromic luminescence. This work not only realized efficient and controllable aggregation/solid/film fluorescence from a salicylaldehyde Schiff-base-functionalized 1,8-naphthalimide luminophore but also provided a strategy for constructing NPI-based smart fluorescent materials.

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来源期刊

Journal of Molecular Structure 化学-物理化学

CiteScore

7.10

自引率

15.80%

发文量

2384

审稿时长

45 days

期刊介绍： The Journal of Molecular Structure is dedicated to the publication of full-length articles and review papers, providing important new structural information on all types of chemical species including: • Stable and unstable molecules in all types of environments (vapour, molecular beam, liquid, solution, liquid crystal, solid state, matrix-isolated, surface-absorbed etc.) • Chemical intermediates • Molecules in excited states • Biological molecules • Polymers. The methods used may include any combination of spectroscopic and non-spectroscopic techniques, for example: • Infrared spectroscopy (mid, far, near) • Raman spectroscopy and non-linear Raman methods (CARS, etc.) • Electronic absorption spectroscopy • Optical rotatory dispersion and circular dichroism • Fluorescence and phosphorescence techniques • Electron spectroscopies (PES, XPS), EXAFS, etc. • Microwave spectroscopy • Electron diffraction • NMR and ESR spectroscopies • Mössbauer spectroscopy • X-ray crystallography • Charge Density Analyses • Computational Studies (supplementing experimental methods) We encourage publications combining theoretical and experimental approaches. The structural insights gained by the studies should be correlated with the properties, activity and/ or reactivity of the molecule under investigation and the relevance of this molecule and its implications should be discussed.