Theoretical Study of Three Ratiometric 1,8-naphthalimide Fluorescent Probes for Hydrogen Sulfide Detection

Area of Science:

• Computational Chemistry
• Chemical Sensing
• Materials Science

Background:

• Ratiometric fluorescent probes are crucial for sensitive and selective detection of analytes.
• Hydrogen sulfide (H2S) plays vital roles in biological processes, necessitating accurate detection methods.
• 1,8-naphthalimide derivatives are widely used as fluorescent platforms due to their favorable photophysical properties.

Purpose of the Study:

• To theoretically investigate three ratiometric 1,8-naphthalimide fluorescent probes designed for hydrogen sulfide (H2S) detection.
• To elucidate the structure-property relationships influenced by substituent modifications on the 1,8-naphthalimide core.
• To provide a theoretical basis for the design of novel and improved H2S fluorescent probes.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to optimize probe geometries.
• Time-Dependent Density Functional Theory (TD-DFT) was used to compute electronic spectra.
• Frontier molecular orbital (FMO) analysis and energy gap calculations were performed.

Main Results:

• Substituent changes minimally impacted the core 1,8-naphthalimide structure, primarily affecting attached regions.
• Electron-donating or withdrawing substituents significantly influenced the electronic spectra of the probes.
• Intramolecular charge transfer (ICT) processes were identified in the probes and their reaction products.
• The energy gap (HOMO-LUMO) analysis provided insights into the electronic transitions.

Conclusions:

• The theoretical study offers a fundamental understanding of how substituents affect the performance of 1,8-naphthalimide-based H2S probes.
• The findings rationalize experimental observations and guide the rational design of next-generation fluorescent sensors.
• This work contributes to the advancement of chemical sensing technologies through theoretical chemistry insights.