Photophysical behaviour, solvatochromism, and silver nanoparticle-induced superquenching of (E, E)-2,5-Bis(3,4,5-trimethoxystyryl) pyrazine with DFT calculations

The fluorescence quantum yield (ϕ_f), electronic transition dipole moment (µ₁₂), molar absorptivity (ε), and fluorescence lifetime (τ_f) of (E, E)-2,5-Bis(3,4,5-trimethoxystyryl) Pyrazine (BTMSP) were studied in various mediums. The medium's polarity significantly affects fluorescence spectra, showing that the BTMSP is more polar in an excited state. Exciton emission was found in solid crystals of BTMSP at 550 nm upon excitation at 400 nm. The dipole moments of the ground and excited states were evaluated based on the Stokes shift and solvent polarity, showing a higher polarity of 6.22 Debye for the excited state than 2.02 Debye for the ground state. pKa and pKa* values for BTMSP have been determined as 1.95 and 10.88, respectively, indicating the higher basicity of the excited state. The green fluorescence (462-525 nm) was caused by the laser activity of BTMSP dye (0.5 mM) in DMSO, DMF, CH₃CN, and dioxane when excited at 337.1 nm by a pulsed nitrogen laser. Fluorescence superquenching of BTMSP was detected using silver nanoparticles (AgNPs) in dynamic and static pathways. The Geometric and electrical structures of BTMSP dye were investigated using DFT methodologies. The outcomes of the experiments and the hypothesis were both consistent. The emission spectra of BTMSP are also studied in cationic and anionic surfactants to determine the critical micelle concentration.