# Optical and Computational Studies on a Triazine Derivative of Dual Fluorescence Enhancement/Superquenching Upon Nanoparticle Interactions

## TL;DR

This paper explores a triazine dye that changes its fluorescence when interacting with metal nanoparticles, which could be useful for biosensing and diagnostics.

## Contribution

The study introduces a new triazine derivative with dual fluorescence enhancement and quenching properties upon interaction with metal nanoparticles.

## Key findings

- Triazine I shows superquenching with silver nanoparticles and fluorescence amplification with gold nanoparticles.
- DFT calculations support the experimental results and provide insights into the dye's electronic properties.
- The dye's optical behavior is solvent-dependent and tunable for biosensing applications.

## Abstract

Derivatives of 1,2,4-triazine have emerged as versatile scaffolds with broad pharmacological and biological potential, prompting deeper exploration of their optical behavior. In this study, we investigate the photophysical properties of a novel 1,2,4-triazine dye, 4-amino-6-(4-methoxyphenyl)-1,4,6,7 tetrahydrothieno [2,3-e] [1,2,4] triazine-3(2 H)-thione (Triazine I) with a focus on its interaction with noble metal nanoparticles. The synthesized dye was structurally characterized using FTIR, 1H-NMR, 13C-NMR, and mass spectrometry to confirm its purity and molecular structure. Silver (Ag-NPs) and gold (Au-NPs) nanoparticles were synthesized via a chemical reduction method and thoroughly characterized using UV–vis spectroscopy, TEM, DLS, Zeta Potential, and XRD, confirming their successful formation, stability, and crystalline nature. Spectroscopic investigations revealed solvent-dependent absorption and emission behavior of Triazine I, along with a dual fluorescence response in the presence of nanoparticles: superquenching by Ag-NPs via non-radiative decay enhancement, and fluorescence amplification by Au-NPs through radiative enhancement (MEF). These findings open promising avenues for using such systems in advanced fluorescence-based biosensing and immunoassays. Furthermore, DFT-based computational studies provided insights into molecular geometry, electronic transitions, and electrostatic potential, reinforcing experimental observations and guiding future molecular de sign. This integrated experimental–theoretical approach highlights Triazine I as a promising candidate for tunable optical applications, particularly in bioimaging and diagnostic platforms.

The online version contains supplementary material available at 10.1007/s10895-025-04474-w.