Photo-Physical Characteristics of Janus Green B in Different Solvents and its Interaction Mechanism with Silver Nanoparticles

Abstract

This work explores the effects of solvent polarity on Janus Green B (JGB) photophysical properties. The Lippert-Mataga, Billot, and Ravi equations were utilized to calculate the singlet-state excited dipole moments (µ_e) and ground state dipole moments (µ_g) using absorption and fluorescence spectra analyses. The results showed an increase in the former, which is suggestive of electronic structural alterations upon excitation. Analysis of fluorescence quantum yield values revealed that JGB's environment had an impact on its emission characteristics; it was particularly sensitive to silver nanoparticles, suggesting possible interactions. While simulations of electron density, electrostatic potential, and energy gap (E_g) helped to understand the electronic structure of JGB, theoretical absorption spectra produced by Time Dependent Density Function Theory (TD-DFT) calculations offered insights into electronic transitions during absorption. To sum up, the present study contributes to our comprehension of the molecular behavior of JGB in various solvents by elucidating the intricate relationship among solvent polarity, molecular environment, and interactions with silver nanoparticles. Additionally, theoretical computations support the interpretation of experimental results.

Keywords: Fluorescence; Janus Green B; Photophysical Properties; Quantum Yield; TD-DFT.

Fig. 1

(a) Gas phase electron density of JGB, (b) the JGB gas phase’s electrostatic potential using TD-DFT/Dmol³ applications

Fig. 2

Absolute values of HOMO and LUMO states energy for JGB

Fig. 3

The simulated absorption spectra of JGB in different solvents using DFT-Dmol³ simulation

Fig. 4

absorption spectra of 1 × 10^− 5 mol dm^− 3 of Janus Green B in different solvents

Fig. 5

(a) Relationships between spectral properties in steady-state of Janus Green B, (b) Dependence of v_abs and v_em on the empirical solvent polarity parameter E_T (30) of Janus Green B

Fig. 6

Emission spectra of 1 × 10^-5 mol dm^-3 of JGB in different solvents λ_ex = 295 nm

Fig. 7

Fluorescence increasing of 2 × 10^− 5 mol. dm^− 3 of JGB by silver nanoparticle in water

Fig. 8

JGB’s normalized emission spectrum measures 2 × 10^− 5 mol dm^− 3, while Ag NPs in water have an absorption spectrum measuring 6.15 × 10^− 5 mol dm^− 3