title: Investigation of role of silver nanoparticles on spectroscopic properties of biologically active coumarin dyes 4PTMBC and 1IPMBC.
abstract: The role of silver nanoparticles on spectroscopic properties of biologically active coumarin dyes 4-p-tolyloxymethyl-benzo[h]coumarin (4PTMBC) and 1-(4-iodophenoxymethyl)-benzo[f]coumarin (1IPMBC) has been investigated using absorption and fluorescence spectroscopy. Silver nanoparticles are synthesized by chemical reduction method and the estimated size by Mie theory is 12 nm. The absorption spectral changes of dyes in the presence of silver nanoparticles suggest their possible interaction with silver nanoparticles. The apparent association constants of the interaction are estimated using Benesi-Hildebrand model. Fluorescence quenching has been observed in both the dyes with the addition of silver nanoparticles. The Stern-Volmer plots of fluorescence quenching are found to be nonlinear showing positive deviation. The magnitudes of quenching rate parameter and fluorescence lifetime measurements indicate the presence of both collisional and static quenching mechanisms. The binding constants and the number of binding sites for the static type of quenching have been estimated from the fluorescence data. The role of diffusion, energy transfer and electron transfer processes in fluorescence quenching mechanism has been discussed.
authors.affiliation: Department of Physics, Bangalore Institute of Technology, Bangalore 560 004, India.
authors.forename: U P
authors.initials: UP
authors.lastname: Raghavendra
authors.affiliation: P.G. Department of Studies in Chemistry, K.L.E. Society's P.C. Jabin Science College, Hubli 580 031, India.
authors.forename: Mahantesha
authors.initials: M
authors.lastname: Basanagouda
authors.affiliation: Department of Physics, B.N.M. Institute of Technology, Bangalore 560 070, India. Electronic address: jtrphy2007@gmail.com.
authors.forename: J
authors.initials: J
authors.lastname: Thipperudrappa
mesh_terms: D065966:Absorption, Physicochemical; D004396:Coloring Agents / Q000737:chemistry* / Q000493:pharmacokinetics; D003374:Coumarins / Q000737:chemistry* / Q000493:pharmacokinetics; D004735:Energy Transfer; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer; D053768:Metal Nanoparticles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology; D013050:Spectrometry, Fluorescence
chemical_list: C000610347:1-(4-iodophenoxymethyl)-benzo(f)coumarin; C000610346:4-p-tolyloxymethyl-benzo(h)coumarin; D004396:Coloring Agents; D003374:Coumarins; D012834:Silver
keywords: 1IPMBC; 4PTMBC; Coumarin; Energy transfer; Fluorescence quenching; Silver nanoparticles