Excited State Interaction of Laser Dyes and Silver Nanoparticles in Different Media

Abstract

Quenching the fluorescence of the dyes 3-(4 '-dimethylaminophenyl)-1-(1H-pyrrol-2-yl)prop-2-en-1-one (DMAPrP), 3-(4 '-dimethylaminophenyl)-1-(2-furanyl)prop-2-en-1-one (DMAFP) and 3-(4 '-dimethylaminophenyl)-1-(2-thienyl)prop-2-en-1-one (DMATP) has been investigated in the presence of silver cation and silver nanoparticles in different media. The results of the quenching experiments were analyzed using Stern-Volmer equation. Quenching the fluorescence of the dyes decreased with increasing medium viscosity. The Stern-Volmer constant (K SV) values in the absence and presence of ethylene glycol show that the quenching efficiencies decrease as the medium viscosity increases indicating that the quenching process is a diffusion-controlled process, and this is consistent with a dynamic-type quenching.

Mechanism of 3,3′-Disulfopropyl-5,5′-Dichlorothiacyanine Anion Interaction With Citrate-Capped Silver Nanoparticles: Adsorption and J-Aggregation

“…The strong fluorescence band with the maximum at 490 nm is ascribed to TC fluorescence since AgNPs do not exert any fluorescence in this spectral range and under these experimental conditions. AgNPs induced the concentration dependent decrease of the overall fluorescence intensity, as also observed in previous studies of TC interaction with Au and AgNPs. , In general, the fluorescence quenching can be ascribed to the formation of a nonfluorescent complex between the fluorophore and a quencher. − As can be concluded from DFT calculations, the interaction between oxygen atom from SO 3 – group of TC dye and AgNPs surface resulted probably in complex formation. The close distance between the fluorophore and the metallic nanoparticle enabled the efficient energy transfer, which resulted in fluorescence quenching.…”

“…The linear plots obtained for various experimental conditions fit very well the static quenching model (Figure 5), suggesting that the quenching in this system can be attributed to the formation of quenched complexes between the fluorophore and AgNPs. 56 The value of static quenching constant (K SV = 2.46 × 10 8 M −1 ) is very close to the same value for borate capped AgNPs, 36 as well as for some AuNPs of various size. 59 3.5.…”

“…14,36,38 It was observed previously that the surface plasmon acted as an efficient energy acceptor for the NPs larger than 5 nm, even at the distance of 1 nm between the dye molecule and NPs surface. 56 Assuming that the measured fluorescence can be ascribed to the unbound TC molecules in solution, the free and bound concentrations in the suspension containing 5 × 10 −6 M TC were calculated and presented as the dependence of AgNPs concentration in Figure 6a.…”

Combined Experimental and Computational Study of the In Situ Adsorption of Piroxicam Anions on the Laser-Generated Gold Nanoparticles

“…For the in situ conjugation of Au NPs with Pir, K SV was calculated to be 2.4 × 10 8 M –1 , which indicates that the Au NPs generated in the aqueous solution have an extraordinary strong quenching ability (Supporting Information, Figure S4). , A high value of K SV also indicates a strong association between the nanoparticles and the fluorophore and further substantiates the involvement of a static quenching mechanism for the Au NP–Pir system. ,,, For this static quenching process, the fluorescence spectra of the Au NP–Pir colloidal solution can be also analyzed using the modified Stern–Volmer equation (eq ) ,, where f a is the fraction of accessible fluorescence and K a is the effective quenching constant, which is analogous to the associative binding constant for the quencher–acceptor system . A plot of F 0 /( F 0 – F ) versus [Q] −1 , shown in Figure S6 of the Supporting Information, gives a straight line, where the value of K a can be calculated from the ratio of the intercept and slope.…”

“…60,61 A high value of K SV also indicates a strong association between the nanoparticles and the fluorophore and further substantiates the involvement of a static quenching mechanism for the Au NP−Pir system. 60,61,71,72 For this static quenching process, the fluorescence spectra of the Au NP−Pir colloidal solution can be also analyzed using the modified Stern−Volmer equation (eq 3) 56,64,65…”