Spectral Investigations on the Fluorescence Quenching of 1,4-dihydroxy-2,3-dimethylanthracene-9,10-dione by Plasmonic Silver Nanoparticles

International audienceSilver nanoparticles (Ag NPs) of different sizes have been prepared by Lee and Meisel's method using trisodium citrate as reducing agent under ultra sonication. Optical absorption and fluorescence emission techniques were employed to investigate the interaction of 1,4-dihydroxy-2,3-dimethyl anthracene-9,10-dione (DHDMAD) with silver nanoparticles. In fluorescence spectroscopic study, we used the DHDMAD and Ag NPs as component molecules for construction of Forster Resonance Energy Transfer (FRET), whereas DHDMAD serve as donor and Ag NPs as acceptor. The surface plasmon resonance (SPR) peak of the prepared silver colloidal solution was observed from 419 nm to 437 nm. The synthesized silver nanoparticles at different heating time intervals were spherical in shape about the size of 25 nm and 55 nm. The fluorescence interaction between silver nanoparticles and DHDMAD confirms the FRET mechanism. According to Forster theory, the distance between silver nanoparticles and DHDMAD and the critical energy transfer distance were calculated and it is increase with heating time

Ground and excited state behavior of 1,4-dimethoxy-3-methylanthracene-9,10-dione in silver nanoparticles: Spectral and computational investigations

International audienceSilver nanoparticles (Ag NPs) of various sizes have been successfully synthesized by the simple and convenient Creighton method using sodium borohydride as the reducing agent under microwave irradiation. Optical absorption and fluorescence emission spectroscopic techniques were employed to investigate the effect of silver nanoparticles on the ground and excited state of 1,4-dimethoxy-3-methylanthracene-9,10-dione (DMMAD). The surface plasmon resonance (SPR) peak of the prepared silver colloidal solution was observed at 400 nm. Fluorescence quenching of DMMAD by silver nanoparticles has been found to increase with increase in the size of Ag. The fluorescence quenching has been explained by Forster Resonance Energy Transfer (FRET) theory between DMMAD and silver nanoparticles. The Stern-Volmer quenching constant and Benesi-Hildebrand association constant for the above system were calculated. DFT calculations were also performed to study the charge distribution of DMMAD in Ag both in ground and excited states. (c) 2013 Elsevier B.V. All rights reserved

Orientation of 1,4-dimethoxy-3-bromomethylanthracence-9,10-dione on silver nanoparticles: SERS studies

International audienceSilver nanoparticles (Ag NPs) are prepared by solution combustion method with glycine as fuel. Silver nanoparticles are characterized by UV-visible spectroscopy, X-ray Diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM). The optical adsorption spectrum shows that the surface plasmon resonance peak of silver is observed at 380 nm. The prepared silver nanoparticles exhibit cubic crystalline structure with grain size of 59 nm. HRTEM image shows that the silver nanoparticles have strain and fivefold symmetry is formed by twinning in the crystal structure. Surface-enhanced Raman scattering (SERS) of 1,4-dimethoxy-3-bromomethyl-9,10anthraquinone dione (DMBMAD) adsorbed on silver nanoparticles has been investigated. The orientation of DMBMAD on silver nanoparticles has been inferred from nRs and SERS spectral features. The observed spectral feature corroborated that DMBMAD would absorb on silver surface with 'stand-on' orientation through the high intensity of C-H out-of-plane bending mode, C-Br stretching, ring stretching and C=O. In present case we used the DMBMAD and Ag NPs as component molecules for energy gap analysis, whereas DMBMAD serve as donor and Ag NPs as acceptor. The calculated HOMO and LUMO energy gap shows that charge transfer occur within molecule and Ag NPs. (C) 2013 Elsevier B.V. All rights reserved

Surface Enhanced Raman Spectroscopic investigations of 2-bromo-3-methylamino-1,4-naphthoquinone on silver nanoparticles

International audienceSurface Enhanced Raman Spectroscopic technique has been employed to investigate the orientation of 2-bromo-3-methylamino-1,4-naphthoquinone (BMANQ) on silver nanoparticles. Silver nanoparticles have been prepared by solution combustion method with citric acid as fuel. Silver nanoparticles were characterized by X-ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy (SEM). XRD and morphological results confirmed the nanocrystalline nature of the prepared silver nanoparticles. The observed intense C=O stretching, C-Br stretching and NH2 vibration suggests that the BMANQ molecule may be adsorbed in a 'stand-on' orientation to the silver surface. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy show that charge transfer occurs within the molecule. (C) 2014 Elsevier B.V. All rights reserved

Spectroscopic studies of 1,4-dimethoxy-2,3-dimethylanthracene-9,10-dione on plasmonic silver nanoparticles

International audienceSilver nanoparticles (Ag NPs) of different sizes from 7 nm to 22 nm have been prepared by simple Dirk and Charles chemical method and characterized using UV-vis spectroscopy and high resolution transmission electron microscopy (HRTEM). Fluorescence quenching of 1,4-dimethoxy-2,3-dimethylanthracene-9,10-dione (DMDMAD) by silver nanoparticles has been investigated by fluorescence spectroscopy to understand the role of quenching mechanism. Furthermore, the intensity of DMDMAD fluorescence emission peak decreases with decrease in the size of the Ag NPs. The fluorescence quenching rate constant and association constant for above system were determined using Stern-Volmer and Benesi-Hildebrand plots. The mechanism of DMDMAD fluorescence quenched by Ag NPs was discussed according to the Stern-Volmer equation. It has been observed that the quenching due to Ag NPs proceeds via dynamic quenching process. The distance between DMDMAD (donor) to Ag NPs (acceptor) and the critical energy transfer distance were estimated based on the Forster Resonance Energy Transfer (FRET) theory. (C) 2014 Elsevier B.V. All rights reserved

Surface enhanced Raman spectral studies of 2-bromo-1,4-naphthoquinone

International audienceSilver nanoparticles have been synthesized by a simple and inexpensive solution combustion method with urea as fuel. The structural and morphology of the silver nanoparticles were investigated through X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersion Spectra (EDS) techniques. Structural and morphological results confirmed the nanocrystalline nature of the silver nanoparticles. Density Functional Theory (DFT) calculations were also performed to study the ground and excited state behavior of 2-bromo-1,4-naphthoquinone (2-BrNQ) and 2-BrNQ on silver nanoparticles. Surface-Enhanced Raman Scattering (SERS) spectra of 2-BrNQ adsorbed on silver nanoparticles were investigated. The C=O, C-H in-plane bending and C-Br stretching modes were enhanced in SERS spectrum with respect to normal Raman spectrum. The spectral analysis reveals that the 2-BrNQ adsorbed 'stand-on' orientation on the silver surface. Density Functional Theory (DFT) calculations are also performed to study the vibrational features of 2-BrNQ molecule and 2-BrNQ molecule on silver surface. (C) 2014 Elsevier B.V. All rights reserved

Synthesis and Conformational Analysis of [3-(6-Chloropyridazin-3-yl)-3,4-Dihydropyridazino[4,5-b]Quinoxalin-2(1De )-yl](Phenyl)Methanone

International audience[3-(6-Chloropyridazin-3-yl)-3,4-dihydropyridazino[4,5-b]quinoxalin-2(1H) -yl](phenyl)methanone has been synthesized and its two stable forms were isolated. For the establishment of their structures, B3LYP geometry and energy and GIAO/B3LYP NMR calculations of possible conformers using the polarizable continuum model were performed. The differences in calculated spectra allow attributing calculated structures and obtained substances by their H-1 and C-13 NMR. The conformer ratio correlates with their calculated Gibbs energies

Influence of Silver Nanoparticles on 2,3-Bis(Chloromethyl)Anthracene-1,4,9,10-Tetraone

International audienceSize effect of silver nano particles on the photophysical properties of 2,3-bis(chloromethyl)anthracene-1,4,9,10-tetraone (BCMAT) have been investigated using optical absorption and fluorescence emission techniques. Silver NPs of different sizes have been prepared by two different methods. Quenching of fluorescence of BCMAT has been found to increase with decrease in the size of the silver NPs. Stern-Volmer quenching constants have also been calculated

DFT and SERS Study of Adsorption of 1,4-Dimethoxy-2-nitro-3-methylanthracene-9,10-dione onto Silver Nanoparticles

International audienceSurface-enhanced Raman scattering (or spectroscopy), commonly known as SERS, has been employed to investigate the adsorption mechanism and orientation of 1,4-dimethoxy-2-nitro-3-methylanthracene-9,10-dione (DMNMAD) molecule onto silver. Silver nanoparticles (Ag NPs) were synthesized based on a solution combustion method using citric acid as a fuel. Scanning electron microscopy and transition electron microscopy studies confirm the crystalline nature and morphology of the synthesized silver nanoparticles. Theoretical normal Raman spectra (nRs) and SERS spectra of the DMNMADmolecule, simulated based on DFT/B3PW91 level of theory were validated experimentally. Experimental and theoretical vibrational modes correlate well, confirming the reliable assignments of the vibrational bands. Enhancement of C=O stretching and C-H in-plane vibrational modes in the SERS spectrum indicates the 'stand-on' orientation of the molecule on the silver nanoparticles after adsorption. The frontier molecular orbitals confirm the charge transfers between the molecule and silver nanoparticles following the process of adsorption. As anthraquinone derivatives have been recently used as potent anti-tumour drugs, the adsorption studies reported in the current investigation can pave way to the potential application of DMNMAD in drug delivery

Adsorption of N-(1-(2-bromopheny1)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide on silver nanoparticles: SERS investigation

International audienceSERS provides essential data regarding the interaction of molecules in drugs with DNA. In the present study silver nanoparticles were synthesized using a solution combustion method with urea as fuel. The prepared silver nanoparticles are rod like structure. Surface-enhanced Raman scattering (SERS) of N-(1-2-bromopheny1)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide (BrS) adsorbed on the silver nanoparticle was studied. The nRs and Raman spectral analysis reveal that the BrS adsorbed tilted orientation on the silver surface. Vibrational modes of nRs along with HF calculations are also performed to study the HOMO and LUMO behavior and vibrational features of BrS. (C) 2014 Elsevier B.V. All rights reserved