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1.
《Vibrational Spectroscopy》2010,52(2):162-167
The complexes of benzotriazole (BTAH) with Ag, Cu, Fe, Zn and Ni were prepared respectively in the non-aqueous solution by the direct electrochemical synthesis and characterized by microanalysis and normal Raman spectroscopy. The influence of the neutral ligand of triphenylphosphine (pph3) on the coordination process was deduced by the normal Raman spectroscopy and electrochemistry. The metals were classified into two categories. For the first type, such as Cu and Ag, CuBTA and AgBTA were obtained in the solution without pph3. The introduction of pph3 led to its participation in the coordination processes of BTAH with Cu or Ag and appeared in the final complex. Fe, Zn and Ni belonged to the second type, there was no influence on the coordination of BTAH with Zn, Ni and Fe, i.e., the final complexes were Fe(BTA)2, Zn(BTA)2 and Ni(BTA)2, respectively, in the solution with/without pph3. The electrochemical results revealed that the BTAH can inhibit the corrosion of all the above metals, and the introduction of pph3 resulted in the decrease of inhibition efficiency to Cu surface, while no influence was observed on the Ni surface. The different role of pph3 was explained in terms of hard/soft acids and bases rule and coordination mechanism was proposed. 相似文献
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A comparative Raman spectroscopy study of triphenylphosphine (TPP), monosulfonated triphenylphosphine (TPPMS) and trisulfonated triphenylphosphine (TPPTS) is reported. The characteristic modes for each molecule were evidenced and we suggest assignments for the majority of the modes. A detailed study of the phenyl breathing mode (around 1000 cm−1) shows that in the case of TPP, the three rings are nonequivalent, whereas for TPPTS, the sulfonate substituant seems to contribute to stabilise the molecule structure so as the rings are equivalent. The TPPMS spectrum is a medium case between the extreme cases of TPP and TPPTS and presents the characteristics of the two previous spectra. 相似文献
4.
Single crystals of diglycine perchlorate (DGPCl) and deuterated diglycine perchlorate (DDGPCl) are synthesized and studied using differential scanning calorimetry (DSC) and Raman spectroscopy. DSC data indicated that both DGPCl and DDGPCl undergo a reversible first-order phase transition (solid-solid) at −11.5 °C and −9.3 °C, respectively. The Raman spectra of DGPCl and DDGPCl obtained at ambient temperature are analyzed to infer on the strength of hydrogen bonding in this compound relative to the parent compounds. The occurrence of NH stretching frequency at higher value in DGPCl in comparison with glycine suggests presence of a weak N–H?O hydrogen bond in DGPCl than in glycine. The lower isotropic melting temperature of DGPCl as compared to that of glycine is understood on the basis of the relative strength of hydrogen bonding in these compounds. 相似文献
5.
De Gelder J Scheldeman P Leus K Heyndrickx M Vandenabeele P Moens L De Vos P 《Analytical and bioanalytical chemistry》2007,389(7-8):2143-2151
Endospores and endospore-forming bacteria were studied by Raman spectroscopy. Raman spectra were recorded from Bacillus licheniformis LMG 7634 at different steps during growth and spore formation, and from spore suspensions obtained from diverse Bacillus and Paenibacillus strains cultured in different conditions (growth media, temperature, peroxide treatment). Raman bands of calcium dipicolinate
and amino acids such as phenylalanine and tyrosine are more intense in the spectra of sporulating bacteria compared with those
of bacteria from earlier phases of growth. Raman spectroscopy can thus be used to detect sporulation of cells by a characteristic
band at 1,018 cm–1 from calcium dipicolinate. The increase in amino acids could possibly be explained by the formation of small acid-soluble
proteins that saturate the endospore DNA. Large variations in Raman spectra of endospore suspensions of different strains
or different culturing conditions were observed. Next to calcium dipicolinate, tyrosine and phenylalanine, band differences
at 527 and 638 cm–1 were observed in the spectra of some of the B. sporothermodurans spore suspensions. These bands were assigned to the incorporation of cysteine residues in spore coat proteins. In conclusion,
Raman spectroscopy is a fast technique to provide useful information about several spore components.
Figure A difference spectrum between Raman spectra of B. licheniformis LMG 7634 cultured for 6 days and 1 day, together with the
reference Raman spectrum of calcium dipicolinate 相似文献
6.
Laura C. Mecker Katherine M. Tyner John F. Kauffman Sergey Arzhantsev Daniel J. Mans Connie M. Gryniewicz-Ruzicka 《Analytica chimica acta》2012
Melamine adulteration of food and pharmaceutical products is a major concern and there is a growing need to protect the public from exposure to contaminated or adulterated products. One approach to reduce this threat is to develop a portable method for on-site rapid testing. We describe a universal and selective method for the detection of melamine in a variety of solid matrices at the 100–200 μg L−1 level by surface enhanced Raman spectroscopy (SERS) with gold nanoparticles. With minimal sample preparation and the use of a portable Raman spectrometer, this work will lead to field-based screening for melamine adulteration. Citrate coated gold nanoparticles (Au NPs) were investigated for both colorimetric and Raman-based responses. Several non-hazardous solvents were evaluated in order to develop a melamine extraction procedure safe for field applications. Au NP agglomerates formed by the addition of isopropanol (IPA) prior to sample introduction enhanced the Raman signal for melamine and eliminated matrix interference for substrate formation. The melamine Raman signal resulted in a 105 enhancement through the use of Au NP agglomerates. To our knowledge, we have developed the first portable SERS method using Au NPs to selectively screen for the presence of melamine adulteration in a variety of food and pharmaceutical matrices, including milk powder, infant formula, lactose, povidone, whey protein, wheat bran and wheat gluten. 相似文献
8.
《Journal of Coordination Chemistry》2012,65(20):3296-3305
1-(2-Pyridyl)benzotriazole (L1) and 1-(4-pyridyl)benzotriazole (L2) with transition metal cations Co(II), Ni(II) and Cu(II) give four coordination complexes, [{Cu(L1)2(H2O)2} · 2NO3] (1), [{Co(L1)2(H2O)2} · 2NO3] (2), [Ni(L2)2(NO3)2(H2O)2] (3), and [Cu2(L2)2(CH3COO)4] (4). In 1–4, different supramolecular frameworks are formed through hydrogen bonding and/or π–π interactions. 相似文献
9.
Kalbác M Kavan L Zukalová M Dunsch L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(20):6231-6236
Raman spectroscopy and in situ Raman spectroelectrochemistry have been applied to the study of the lithium vapor doping of C60@SWCNTs (peapods; SWCNT=single-walled carbon nanotube). A strong degree of doping was proven by the disappearance of the radial breathing mode (RBM) of the SWCNTs and by the attenuation of the tangential (TG) band intensity by two orders of magnitude. The lithium doping causes a downshift of the Ag(2) mode of the intratubular C60 by 27 cm(-1) and changes the resonance condition of the encapsulated fullerene. In contrast to potassium vapor doping, the strong downshift of the TG band was not observed for lithium doping. The peapods treated with lithium vapor remained partially doped even when they were exposed to humid air. This was reflected by a reduction in the intensity of the nanotube and the fullerene modes and by the change in the shape of the RBM band compared with that of the undoped sample. The Ag(2) mode of the intratubular fullerene was not resolved after contact of the lithium-doped sample with water. Lithium insertion into the interior of a peapod and its strong interaction with the intratubular fullerene is suggested to be responsible for the air-insensitive residual doping. This residual doping was confirmed by in situ spectroelectrochemical measurements. The TG band of the lithium-doped peapods did not undergo an upshift during the anodic doping, which points to the formation of a stable exohedral metallofullerene peapod. 相似文献
10.
The dye nuclear fast red has been detected and determined semi-quantitatively by means of surface enhanced resonance Raman scattering (SERRS) and surface enhanced Raman scattering (SERS), using laser exciting wavelengths of 514.5 and 632.8 nm, respectively, by employing a citrate-reduced silver colloid. A good linear correlation is observed for the dependence of the intensities of the SERRS bands at 989 cm−1 (R=0.9897) and 1278 cm−1 (R=0.9872) on dye concentration over the range 10−9 to 10−7 M, when using an exciting wavelength of 514.5 nm. At dye concentrations above 10−7 M, the concentration dependence of the SERRS signals is non-linear. This is almost certainly due to the coverage of the colloidal silver particles being in excess of a full monolayer of the dye. A linear correlation is also observed for the dependence of the intensities of the SERS bands at 989 cm−1 (R=0.9739) and 1278 cm−1 (R=0.9838) on the dye concentration over the range 10−8 to 10−6 M when using an exciting wavelength of 632.8 nm. Strong fluorescence prevented collection of resonance Raman scattering (RRS) spectra from powdered samples or aqueous solutions of the dye using an exciting wavelength of 514.5 nm, but weak bands were observed in the spectra obtained from both powdered and aqueous samples of the dye using an exciting wavelength of 632.8 nm. A study of the pH dependence of SERRS/SERS and UV–VIS absorption spectra revealed the presence of different ionisation states of the dye. The limits of detection for nuclear fast red by SERRS (514.5 nm), SERS (632.8 nm) and visible spectroscopy (535 nm) are 9, 89 and 1000 ng ml−1, respectively. 相似文献
11.
Studies of the surface wettability and hydrothermal stability of methyl-modified silica films by FT-IR and Raman spectra 总被引:1,自引:0,他引:1
Fourier transform infrared (FT-IR) and Raman spectroscopy were employed to study the hydrothermal stability and the influence of surface functional groups on the surface wettability of methyl-modified silica films. The surface free energy parameters of the silica films were determined using the Lifshitz-van der Waals/acid–base approach. The thermal decomposition mechanisms of the CH3 groups in the methyl-modified silica material are proposed. The results show that with the increase of methyltriethoxysilane (MTES)/tetraethylorthosilicate (TEOS) ratio, the surface free energy and surface wettability of the silica films decrease greatly. This is mainly because of the contribution of the acid–base term; the intensity of Si–CH3 groups increases at the expense of the intensity of O–H groups in the samples. The surfaces of the methyl-modified silica films exhibited predominantly monopolar electron-donicity. The contact angle on the silica film surface reaches its maximum value when calcination is performed at 350 °C. Thermogravimetric analysis implies that some low molecular weight species, such as H2, CH4, and C, are eliminated upon thermal decomposition of the –CH3 groups. The Si–CH3 and –CH3 vibrational bands diminish in intensity as the calcination temperature is increased, disappearing completely when the calcination temperature is increased to 600 °C. When the calcination temperature is increased to 750 °C, the free carbon and CSi4 species will be formed. 相似文献
12.
By using 31P NMR and IR techniques it is established that the basicities of triphenylphosphine m-trisulfonate (TPPTS) and triphenylphosphine (PPh3) are in the same order of magnitude. This highly hydrosoluble phosphine is a convenient ligand for the synthesis of hydrosoluble coordination compounds of molybdenum(0), palladium(II), platinum(II) and rhodium(I). The exchange of TPPTS with ligands other than PPh3 (nitriles, carbon monoxide, olefins, chloride) can be used to obtain the desired complexes. However, because redox reactions between metal salts, water and TPPTS are possible, the synthesis of lowvalent precursors must be carried out and the experimental conditions have to be carefully controlled to avoid side-reactions and the participation of the sulfonate anions in competitive reactions. 相似文献
13.
Jiming Hu Tianyu Wang Damien Moigno Minawaer Wumaier Wolfgang Kiefer Jungang Mao Qiaofeng Wu Fei Niu Yinghong Gu Qingqi Chen Jinshi Ma Haitao Feng 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(14):2737-2743
The Fourier-transform Raman (FT-Raman), infrared (FT-IR), and UV-visible absorption spectra of four dipyrrinones and two mesobilirubins have been investigated in the solid state and in CH2Cl2 solutions. A detailed spectral analysis, assignment and discussion of these spectra are presented. The bands at 1735-1738, 1691-1707 and 1359-1377 cm(-1) which were assigned to the stretching vibrations of the C-O-C and C-O-H and symmetric deformation of C-H bonds, respectively, can act as a marker to distinguish the compounds of this class. The striking differences between the spectra of the compounds suggest that mesobilirubin XIIIalpha is tending to adopt as ridge-tile conformation, rather than linear conformation. 相似文献
14.
Su Y He Q Yan X Fei J Cui Y Li J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(12):3370-3375
The design and fabrication of various nanostructures with predefined geometry and composition is a big challenge of nanotechnology. Here we demonstrate an Au nanoflake film replicated from a self-assembled, well-ordered, dipeptide flower-like hierarchical architecture. Such morphology can give rise to useful and remarkable surface-enhanced Raman spectroscopy (SERS) properties. We obtained these nanostructures by using a scaffold of flake-built spherical dipeptide aggregations. Gold nanoparticles were sputtered on the surface of as-assembled dipeptide by an etching system. After removing the dipeptide templates by ethanol, a metal crust was left with a morphology similar to that of the dipeptide hierarchical structure. The different steps within the process were monitored by using electron microscopy, energy-dispersive spectrum (EDS) analysis and atomic force microscopy (AFM). Cyclic voltammetry and Raman spectra were employed to prove the SERS effect of the obtained Au substrates. The enhancement factor is estimated to be about 10(4) for 4-mercaptobenzoic acid (4-MBA) molecules on the Au nanoflake surfaces. 相似文献
15.
Tao S Hong B Kerong Z 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):1364-1368
Polyanilines doped with (HCl+KCl) and (HCl+CoCl2) were prepared by co-doping method, respectively. For comparison, polyaniline emeraldine salt (ES) by doping with HCl and its emeraldine base (EB) form were also synthesized. The co-doped polyanilines, ES and EB samples were all characterized by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy aiming to understand the transformations in the different doping status. The results show that the doping degree of K+ ions is considerably higher than that of Co2+ ions under the same co-doping conditions possibly due to different pseudoprotonation constants of EB with K+ ions and Co2+ ions. Moreover, morphology difference of polyaniline co-doped with alkaline metal ions or transition meal ions may arise from different coordination geometry of metal ions. Nevertheless, there are similar chemical transformations of quinoid units to benzenoid ones on polyaniline backbones for the ES and both co-doped samples. And the polyaniline backbones co-doped with H+ and metal cations are found to attain weaker charge delocalization than the ES which is doped solely with H+. 相似文献
16.
The determination of film thickness is of prime importance in the quality assurance of coated pharmaceutical preparations. The rapid measurement of this parameter is problematic for multi-particulate pellet systems. The aim of this study was to apply the Raman spectroscopic method for the determination of the thickness of polymer coating on pellets. The change of Raman intensity was compared with measured film thickness, which was calculated from the change of the geometric parameters of the pellets, measured with an image-analyzing system. The results revealed that despite some difficulties Raman spectroscopy is a suitable method for the fast and accurate determination of film thickness on multi-particulate systems. 相似文献
17.
H.G.M Edwards M.J.P Falk 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》1997,53(14):2685-2694
The application of Fourier-transform (FT)-Raman spectroscopy to the non-destructive analysis of plant biomaterials, comprising ten different waxes, is illustrated in this work. All the wax specimens studied are multicomponent systems and comparison of the individual spectra was effected. This leads to a means of distinguishing the individual wax specimen using FT-Raman spectroscopy. The samples were not pre-treated before analysis and were used directly from their respective storage collections. 相似文献
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Using a method of collecting nanoparticles at a water/hexane interface in a close-packed monolayer film and transferring such films onto a solid substrate, three-dimensional multilayer films of nanoparticles were formed. The packed nanoparticles were gold nanospheres (NS) with a 26 nm diameter or gold nanorods (NR) with a 31 nm diameter and 74 nm length. We investigated variations in the surface enhanced Raman scattering (SERS) intensities from such nanoparticle films as the layer compositions were changed. The films stacked with NR layers generated much higher SERS intensity than those of NS layers. The SERS intensities from both kinds of films increased as the number of layers were increased. However, when the NR layer and NS layer were stacked alternately, SERS intensity varied in a zigzag fashion. It was found that the structure of top layer plays a distinguishable role in generating strong SERS enhancement while the lower layers contribute to SERS with less dependency on structures. Interlayer coupling as well as intralayer coupling was considered in order to explain the observations. 相似文献
20.
A laueite mineral sample from Lavra Da Ilha, Minas Gerais, Brazil has been studied by vibrational spectroscopy and scanning electron microscopy with EDX. Chemical formula calculated on the basis of semi-quantitative chemical analysis can be expressed as (Mn2+0.85,Fe2+0.10Mg0.05)∑1.00(Fe3+1.90,Al0.10)∑2.00(PO4)2(OH)2·8H2O.The laueite structure is based on an infinite chains of vertex-linked oxygen octahedra, with Fe3+ occupying the octahedral centers, the chain oriented parallel to the c-axis and linked by PO4 groups. Consequentially not all phosphate units are identical. Two intense Raman bands observed at 980 and 1045 cm−1 are assigned to the ν1 PO43− symmetric stretching mode. Intense Raman bands are observed at 525 and 551 cm−1 with a shoulder at 542 cm−1 are assigned to the ν4 out of plane bending modes of the PO43−. The observation of multiple bands supports the concept of non-equivalent phosphate units in the structure. Intense Raman bands are observed at 3379 and 3478 cm−1 and are attributed to the OH stretching vibrations of the hydroxyl units. Intense broad infrared bands are observed. Vibrational spectroscopy enables subtle details of the molecular structure of laueite to be determined. 相似文献