Surface-enhanced Resonance Raman Study Research Articles

Distorted Phthalocyanines by Click Chemistry: Photoacoustic, Photothermal, and Surface-Enhanced Resonance Raman Studies.

Distortion of nominally planar phthalocyanine macrocycles affects the excited state dynamics in that most of the excited-state energy decays through internal conversion. A click-type annulation reaction on a perfluorophthalocyanine platform appending a seven-membered ring to the β-positions on one or more of the isoindoles distorts the macrocycle and modulates solubility. The distorted derivative enables photoacoustic imaging, photothermal effects, and strong surface-enhanced resonance Raman signals.

The Effect of Ag Nanoparticles on Surface-Enhanced Luminescence from Au Nanovoid Arrays

Studies comparing the effect of adding two different nanoparticle compositions on the plasmonic properties of Au nanovoid arrays were undertaken. Surface-enhanced resonance luminescence and surface-enhanced resonance Raman studies comparing dispersed Ag nanoparticles and Ag nanoparticle aggregates on gold nanovoid arrays were undertaken. These studies showed that using Ag nanoparticle aggregates increased both luminescence and Raman efficiency relative to when dispersed nanoparticles were used; in addition, these studies also showed that adding dispersed Ag nanoparticles supported a more reproducible enhancement in luminescence and Raman across the substrate compared to using Ag nanoparticle aggregates. Finite element analysis simulations indicated that surface plasmon polariton distribution in the sample was affected by the presence of the Ag nanoparticles on the Au nanovoid array.

The impact of urea-induced unfolding on the redox process of immobilised cytochrome c

We have studied the effect of urea-induced unfolding on the electron transfer process of yeast iso-1-cytochrome c and its mutant K72AK73AK79A adsorbed on electrodes coated by mixed 11-mercapto-1-undecanoic acid/11-mercapto-1-undecanol self-assembled monolayers. Electrochemical measurements, complemented by surface enhanced resonance Raman studies, indicate two distinct states of the adsorbed proteins that mainly differ with respect to the ligation pattern of the haem. The native state, in which the haem is axially coordinated by Met80 and His18, displays a reduction potential that slightly shifts to negative values with increasing urea concentration. At urea concentrations higher than 6 M, a second state prevails in which the Met80 ligand is replaced by an additional histidine residue. This structural change in the haem pocket is associated with an approximately 0.4 V shift of the reduction potential to negative values. These two states were found for both the wild-type protein and the mutant in which lysine residues 72, 73 and 79 had been substituted by alanines. The analysis of the reduction potentials, the reaction enthalpies and entropies as well as the rate constants indicates that these three lysine residues have an important effect on stabilising the protein structure in the adsorbed state and facilitating the electron transfer dynamics.

Surface-enhanced resonance Raman study of cytochrome c″ from Methylophilus Methylotrophus

Surface-enhanced resonance Raman (SERR) spectroscopy was employed to study cytochrome c″ (Cyt-c″) adsorbed on a silver electrode. Depending on the electrode potential, the adsorbed Cyt-c″ exists in various conformational states including the native six-coordinated low spin (6cLS) and the five-coordinated high spin (5cHS) configurations of the oxidised and reduced forms, respectively. In contrast to Cyt-c″ in solution, two additional species are found for the adsorbed protein: a 5cHS ferric and a 6cLS ferrous form. The latter species which is only detected at potentials close to the redox potential is ascribed to an intermediate state of the redox process that most likely involves a coupling of electron transfer and ligand (de)protonation.

Resonance Raman and surface-enhanced resonance Raman studies of polymer-modified electrodes which mimic heme enzymes

Iron-5,10,15,20-tetraphenylporphyrin (FeTPP) has been incorporated into films of a coordinating hydrogel polymer support medium, poly(γ-ethyl-L-glutamate) (PEG) functionalised with imidazole pendant arms (PEG-Im), and studied insitu on silver electrodes using a combination of both resonance Raman (RR) and surface-enhanced resonance Raman (SERR) spectroscopy. The SERR spectra give information on the portion of the film close to the electrode surface while RR spectra probe the '‘bulk’' of the film. At open-circuit potentials the RR spectra are characteristic of the expected low-spin FeIII(TPP)(PEG-Im)2 complex formed by axial ligation but the SERR spectra show that, at the electrode surface, the complex is composed primarily of FeIII(TPP)(PEG-Im). The reasons for the difference have been investigated by systematic RR and SERR studies of both PEG-Im and a more inert polymer support based on simple PEG, which does not carry any potentially ligating imidazole pendant arms. On application of a reducing potential (-400 mV vs. SSCE) only partial reduction is observed at the surface of the PEG-Im films. However, RR spectra of the reduced films show complete and reversible conversion to the expected FeII(TPP)(PEG-Im)2 complexes so that the low electrochemical activity near the surface does not prevent efficient electron transport from the electrode surface right through the thickness of the doped polymer layer. There are striking similarities between the properties of this model system, which contains multiple randomly oriented iron porphyrins which are bis-axially coordinated by imidazoles in a solvent accessible poly(amino acid) matrix, and those of cytochrome c3, which is a tetraheme protein of low molecular weight. In cyt c3 the FeIII hemes, which are bis-coordinated by histidine residues, lie close to each other and again show efficient inter-heme electron transfer. The structure of the synthetic PEG-Im film model appears to be sufficiently close in structure to the enzyme that it also reproduces the main features of its behaviour.

Surface-Enhanced Resonance Raman Studies of Spiropyrans (Bips and Derivatives)

Abstract The merocyanine form of BIPS and three of its nitro derivatives were studied by surface—enhanced Raman spectroscopy. It was found that in case of the nitro derivates, the SERS spectra originated from the unprotonated open merocyanine forms, even if the solution was acidified. In case of 6-nitro BIPS, there exist two enantiomers of the closed spiro form with different properties. The photoinduced merocyanine form of the photoactive enantiomer is different from the thermal ring opening product of the photoinactive enantiomer.

Stability of isolated bacterial and photosystem II reaction center complexes on silver electrode surfaces. A surface-enhanced resonance Raman study

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStability of isolated bacterial and photosystem II reaction center complexes on silver electrode surfaces. A surface-enhanced resonance Raman studyRafael Picorel, Randall E. Holt, Randall Heald, Therese M. Cotton, and Michael SeibertCite this: J. Am. Chem. Soc. 1991, 113, 8, 2839–2843Publication Date (Print):April 1, 1991Publication History Published online1 May 2002Published inissue 1 April 1991https://doi.org/10.1021/ja00008a006RIGHTS & PERMISSIONSArticle Views108Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (651 KB) Get e-Alerts Get e-Alerts

Surface-enhanced resonance raman study on adsorption of cyanine dye onto silver chloride colloids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface-enhanced resonance raman study on adsorption of cyanine dye onto silver chloride colloidsJian Wang, Ping Zhang, Tianjing He, Houwen Xin, and Fanchen LiuCite this: J. Phys. Chem. 1988, 92, 7, 1942–1945Publication Date (Print):April 1, 1988Publication History Published online1 May 2002Published inissue 1 April 1988https://doi.org/10.1021/j100318a046RIGHTS & PERMISSIONSArticle Views241Altmetric-Citations35LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (492 KB) Get e-Alerts

Surface enhanced resonance Raman study of phenobarbital-induced rabbit liver cytochrome P-450 LM2

Surface enhanced resonance Raman (SERR) spectroscopy has been used to study the vibrational spectra of the heme of purified rabbit liver cytochrome P-450 LM2 which was adsorbed on colloidal silver suspensions or on a silver electrode. Based on a comparison with the resonance Raman (RR) spectra of the ‘solute’ species the high sensitivity of the SERR technique is demonstrated. Two different features were chosen in order to determine the structural and functional integrity of the adsorbed P-450. Both, substrate-induced spin state changes on the oxidized P-450 and the effect of the thiolate ligand on the oxidation state marker band ν 4 in the reduced P-450 could be observed in the SERR spectra of the adsorbed as well as in the RR spectra of the dissolved enzyme. These findings indicate that the protein structure near the substrate binding site and the coordination by thiolate are not affected by the interaction with the metal surface. Both structural elements are crucial for the function of P-450. Thus the elementary processes of the enzymatic action of P-450 can be investigated by this highly sensitive version of RR spectroscopy.

A surface enhanced resonance Raman study of cobalt phthalocyanine on rough Ag films: Theory and experiment

We present a combined experimental/theoretical study of the coverage and frequency dependence of surface (enhanced) resonance Raman scattering [S(E)RRS] of cobalt phthalocyanine (CoPc) on CaF2 roughened silver films. The experimental spectra indicate a rather strong coverage dependence at very low coverage for excitation at or close to the molecular resonance frequency, with a peak at 0.07 monolayer (ML) followed by a rapid decrease above that. This coverage dependence differs strongly with observations on smooth films, where a much weaker dependence is observed. At very low coverage on the rough Ag films S(E)RRS enhancements comparable to SERS are observed. To model this coverage dependence, we consider the electromagnetic interactions between the adsorbate and substrate, with the substrate modeled as a metal spheroid and the adsorbate as a layer with variable coverage. Two models for this layer are considered, an effective medium model in which the layer is taken to have a coverage dependent dielectric constant, and a coupled dipole model in which both the molecules and metal are taken to be polarizable dipoles. The dependence of field enhancement and S(E)RRS intensity is studied for these two models as a function of frequency, coverage, and Stokes shift. It is found that although there are differences between the two models, the coverage dependence is similar in both, with peak intensities at about 0.1 ML for reasonably prolate spheroids. These models also demonstrate that the drop in intensity above 0.1 ML arises from damping of the plasmon resonance by the adsorbed layer. Interadsorbate interactions are found to play a role in determining the coverage dependence of the S(E)RRS intensity that is secondary to this damping. The large enhancements seen below 0.1 ML suggest that excited state quenching by the surface is not important for this nonfluorescent molecule.

A surface-enhanced resonance Raman study of the photoreduction of methylviologen on a p-indium phosphide semiconductor electrode

ADVERTISEMENT RETURN TO ISSUEArticleNEXTA surface-enhanced resonance Raman study of the photoreduction of methylviologen on a p-indium phosphide semiconductor electrodeQiao Feng and Therese M. CottonCite this: J. Phys. Chem. 1986, 90, 6, 983–987Publication Date (Print):March 1, 1986Publication History Published online1 May 2002Published inissue 1 March 1986https://doi.org/10.1021/j100278a001RIGHTS & PERMISSIONSArticle Views167Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (609 KB) Get e-Alerts

Surface enhanced resonance Raman study on fluorescein dyes

AbstractFluorescein and its derivatives fluoresceinamine and diiodofluoresceiniodoacetamide have been studied by surface enhanced resonance Raman spectroscopy (SERRS). Adsorption of the dyes at the silver/electrolyte interface requires attractive interactions between polar side groups (such as NH2, OH and COOH) with the metal as a prerequisite for Raman enhancement and fluorescence quenching. It was possible to characterize two prototropic forms of fluorescein and fluoresceinamine by their SERR spectra. Only vibrations of the chromophoric part (xanthene) of the molecule contribute to the measured spectra. Substituents in the phenyl ring influence only the ability of adsorption and the structure of the adsorbed molecules.

Resonance Raman and surface-enhanced resonance Raman studies of cytochrome cd1

Resonance Raman and surface-enhanced resonance Raman studies of cytochrome cd1