NMR spectra of icosahedral (Ih and I) fullerenes

By analyzing the topological structures of the three types of icosahedral fullerenes: (1) , (2) and (3) k,\;h,k = 1,2,...} \right)$$ " align="middle" border="0"> , we have obtained theoretically the ¹³C NMR spectra with natural abundance for ¹³C of all the icosahedral (I_h and I) fullerenes.     

Vibration and NMR spectra of dihedral fullerenes

With the help of the topological structures of the dihedral (D_p, D_ph, D_pd; p=5, 6) fullerenes, we have derived the formulas for the decomposition of their nuclear motions into irreducible representations. So their infrared and Raman active modes have been obtained. Furthermore, by use of the concept of the representative patch we have also derived their nuclear magnetic resonance spectra. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 68: 211–217, 1998     

DFT study on electronic properties of single- and double-shell icosahedral fullerenes

Multi-shell fullerenes are widely studied for their interesting properties although comparative studies on single- and multi-shell structures remain scarce. In this work, important electronic features of single- and double-shell icosahedral fullerenes as a function of their sizes were calculated in the framework of the density functional theory. Fully optimized structures were used to get the gap between the highest occupied molecular and the lowest unoccupied molecular orbital (H-L gap), electronegativity, softness and density of the electronic states. This work shows that the H-L gap of the single-shell fullerenes decreases nonlinearly as the nanoparticles size increases, whereas for the double-shell fullerenes an opposite trend is obtained. A decrease of the H-L gap is found going from single- to double-shell fullerenes with similar external sizes, up to a diameter of 3.13 nm. The electron density of states revealed that isolated peaks give way to more dense electronic states for nanoparticles with diameters above 2 nm.     

Electronic spectra and electron structure of fullerene complex (η2-C60)Fe(CO)4

The electronic spectrum of the C₆₀Fe(CO)₄ complex was studied in a toluene solution. The more intense absorption of C₆₀Fe(CO)₄ in the visible region, relative to the free C₆₀, can be attributed to the effect of lower symmetry of the C₆₀ fullerene cage in C₆₀Fe(CO)₄ and, thus, relaxation of selection rules for forbidden internal electronic transitions of C₆₀. No bands of the charge transfer from 3d(Fe) to C₆₀ orbitals were observed in the visible region of the complex spectrum. Assignment of the bands was confirmed by semiempirical calculations of the electronic spectrum.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1453–1458, June, 1996     

Vibrational spectra of Zn(II) complexes of the amino acids with hydrophobic residues

The infrared and Raman spectra of the bis-chelated Zn(II) complexes of the amino acids glycine, alanine, valine, leucine, isoleucine and phenylalanine were recorded and analyzed in relation to its structural peculiarities. Some comparisons between the recorded spectra are also presented and the characteristics of the carboxylate motions as well as those of the metal-to-ligand vibrations are discussed in detail.     

Vibrational spectra of mixed (phthalocyaninato)(porphyrinato) yttrium(III) double-decker complexes: Density functional theory calculations

The vibrational (IR and Raman) spectra of neutral and reduced mixed (phthalocyaninato)(porphyrinato) yttrium(III) double-decker complexes Y(Pc)(Por) and [Y(Pc)(Por)]⁻ [the simplified models of mixed (phthalocyaninato)(porphyrinato) rare earth(III) complexes] are studied using density functional theory (DFT) calculations. The simulated IR and Raman spectra of Y(Pc)(Por) are compared with the experimental IR spectrum of Tb(Pc)(TClPP) and Raman spectrum of Y(Pc)(TClPP), respectively, and many bands can acceptably fit in spite of the different species. On the basis of comparison with the simulated spectra of PbPc and PbPor together with the assistance of normal coordinate analysis, the calculated frequencies in their IR and Raman spectra are identified in terms of the vibrational mode of different ligand for the first time. The calculated frequency at 1048 cm⁻¹ in the IR spectrum of [Y(Pc)(Por)]⁻ with contribution from both Pc and Por vibrational modes is the characteristic IR vibrational mode of the reduced double-decker, while the characteristic IR vibrational mode of Y(Pc)(Por) attributed from the vibration of phthalocyanine monoanion radical Pc⁻ appears at 1257 cm⁻¹. In line with our previous experimental findings that the Raman spectra of M(Pc)(TPP) and M(Pc)(TClPP) are dominated by the Pc vibrational modes, theoretical calculations indicate that most of the Raman vibrational modes contributed from Por ring are covered up by those of Pc ring and thus are hard to be recognized in the Raman spectra of [Y(Pc)(Por)]⁻ and Y(Pc)(Por) due to their much weaker intensity in comparison with that of Pc ligand. Comparison in the IR and Raman spectra between [Y(Pc)(Por)]⁻ and Y(Pc)(Por) also suggests the localization of hole on the Pc ring in the neutral double-decker Y(Pc)(Por). The present work, representing the first detailed DFT study on the vibrational spectra of mixed (phthalocyaninato)(porphyrinato) rare earth(III) double-decker complexes, is useful in helping to understand the vibrational spectroscopic properties of this series of mixed tetrapyrrole ring complexes.     

Vibrational Study of Manganese Ammonium Dihydrogendiphosphate Hydrated Mn0.5NH4H2P2O7·H2O

ABSTRACT

Raman and infrared spectra of manganese ammonium dihydrogendiphosphate hydrated Mn_0.5NH₄H₂P₂O₇·H₂O have been collected and interpreted using factor group analysis. Non-coincidence of the Raman and infrared spectra bands confirms a centrosymmetric structure for Mn_0.5NH₄H₂P₂O₇·H₂O, as previously investigated by X-ray structural study, as well as the joint appearance of ν_as POP and ν_s POP point to a bent POP configuration.     

Vibrational spectra and density functional study of propylgermane

Raman and infrared spectra of propylgermane, CH₃CH₂CH₂GeH₃, and its Ge-deuterated analog, CH₃CH₂CH₂GeD₃, were investigated in their gaseous, liquid and solid states. The normal coordinate treatment was carried out by density functional theory (DFT) calculation, using B3LYP/6-31G^* and 6-311++G^** basis sets, and the corresponding fundamental vibrations were assigned. The trans (T) and gauche (G) forms around the central C–C bond coexisted in the gaseous and liquid states and only the T form existed in the solid state. From the temperature dependent measurements of the Raman spectra in the liquid state, the enthalpy difference was found to be ΔH(T−G)=−0.36±0.02 kcalmol⁻¹ with the T form being more stable. The energy differences between the isomers obtained by DFT calculations were ΔE(T−G)=−0.46 kcalmol⁻¹ and ΔE(T−G)=−0.87 kcalmol⁻¹ by the 6-31G^* basis set and 6-311++G^** basis set, respectively.     

Vibrational Spectroscopy of Ion Irradiated Carbon Containing Macromolecules

A large variety of carbon rich macromolecules has been studied in our laboratory, before, during, and after ion irradiation (3-60 keV ions), by in situ IR and Raman spectroscopies. In this paper we present results obtained on: (a) Films of frozen H₂O:CH₄:N₂ mixtures that have been deposited at low temperature (12 K) on a silicon substrate, and irradiated with fast ions. Irradiation causes the formation of organic refractory residues whose spectra have been recorded and studied also after further irradiation at room temperature. (b) Pentacene (a Polyciclic Aromatic Hydrocarbon, PAH) whose Raman spectra have been studied also during ion irradiation at room temperature. (c) Thin samples of fullerene (C₆₀) films also irradiated at room temperature. Here we discuss some of the most relevant results and compare the spectra of the very different samples that after prolonged irradiation, evolve towards amorphous carbons that have common spectral characteristic. The results are discussed in terms of their astrophysical relevance. It is demonstrated that frozen hydrocarbons, PAHs and fullerenes are rapidly converted to amorphous carbon in space. Amorphous carbon has to be a widespread material in many astrophysical environments.     

Finite group theory for large systems. 3. Symmetry-generation of reduced matrix elements for icosahedral C(20) and C(60) molecules

This paper uses symmetry-generation to simplify the determination of Hamiltonian reduced matrix elements. It is part of a series on using computers to apply finite group theory to quantum mechanical calculations on large systems. Symmetry-generation is an expression of the whole molecule as a sum of symmetry transformations on a smaller reference structure. Then on a suitably-conditioned symmetry-adapted basis, the reduced matrix elements of the Hamiltonian are averages of certain elements of the simpler reference structure matrix. The smaller the reference structure, the greater is the computational savings. Single atom reference structures are used here for the Hückel treatment of icosahedral C(20) and C(60) fullerenes. The analytical power of this approach is illustrated by determining the two bond lengths of C(60) from spectral data.     

Raman spectra of Sr3(PO4)2 and Ba3(PO4)2 orthophosphates at various temperatures

The Raman spectra for Sr₃(PO₄)₂ and Ba₃(PO₄)₂ were investigated in the temperature range from 80 to 1623 K at atmospheric pressure. An unexpected melting of each sample was observed around 1573–1583 K in this study. In the temperature range from 80 to 1323 K, the Raman wavenumbers of all observed bands for Sr₃(PO₄)₂ and Ba₃(PO₄)₂ continuously decrease with increasing temperature. A quantitative analysis on the wavenumbers of Raman bands for both samples reveals that the ν₃ antisymmetric stretching vibrations show the strongest temperature dependence and the ν₂ symmetric bending vibration displays the weakest temperature dependence. The effects of cations on Raman bands are discussed. The reason for the unexpected melting of both samples is mainly attributed to the significant contribution from excess surface energy and the grain-boundary energy that has apparently lowered the melting points of the small samples, i.e., Gibbs–Thomson effect.     

Vibrational spectra of liquid di-iso-propylether

The spectrum of the complex refractive index in the 15,000-100 cm⁻¹ region was determined for liquid di-iso-propylether from transmission studies. In the MIR region very thin layers with thicknesses of a few micrometers had to be used to obtain reliable data. FT-Raman spectra of the liquid are also reported. Identifications for numerous bands observed in the liquid phase were proposed based on results of a conformational analysis and modeling of vibrational spectra using DFT calculations.     

Vibrational spectra of dipropylsulfoxide

FTIR and Raman spectra analysis of pure dipropylsulfoxide (DPSO), binary mixtures of DPSO/CCl(4), and DPSO/water has been first performed. The complex pattern of spectra has been explained on the basis of molecular interactions between DPSO and other molecules and, in the aqueous solutions, the role of both hydrophilic and hydrophobic interactions have been discussed depending on the concentrations. The changes in the intensities and in the frequencies of DPSO bands on concentration have been considered. The curve fitting procedure has been performed for both SO and C-H stretching region, and, on the basis of deconvolution results different type of molecular interactions have been considered. Density function theory DFT/(B3LYP) method has been used to determine the optimized geometry for free DPSO and for 1 DPSO:1 water complex. On the basis of the 6-31+G(d) quality sets parameters, the DFT calculated bond parameters and harmonic vibrations are in a very good agreement with experimental data.     

氯柱硼镁石在盐酸溶液中溶解及相转化平衡溶液的振动光谱分析

The FT-IR difference spectroscopy and the Raman spectroscopy were used to identify the polyborate ions in saturated aqueous solutions during dissolution and transformation of 2MgO·2B₂O₃·MgCl₂·14H₂O in different HCl solutions at 30℃. The assignments of the recorded IR-Spectroscopic frequencies and Raman shift of the borate aqueous solution are given. The existing forms of polyborate anions in saturated aqueous solution and their inter-action have been discussed. The relationships between the existing forms of polyborate anions and the crystallizing solid phases have been gained.     

Vibrational spectral studies of L-citrullinium perchlorate

Infrared and Raman spectra of L-citrullinium perchlorate crystals have been recorded at room temperature. The vibrational assignments of the observed wavenumbers are proposed on the basis of group theoretical analysis. The presence of carbonyl group indicates that the molecule exists in the ionic form. The shifting of stretching and bending wavenumbers indicates the presence of extensive hydrogen bonding in the crystal. The anion fundamentals however continue to be degenerated. This suggests that its symmetry is not affected in the crystal.     

Vibrational spectroscopic studies of (3-mercaptopropyl)trimethoxylsilane sol-gel and its coating

Organosilane sol-gels have been prepared under different conditions from mercaptopropyltrimethoxysilane (MPTMS) and mercaptopropyltriethoxysilane (MPTES). These sol-gels were applied for the thin film coating on aluminum. Vibrational spectroscopy has been employed to trace and to study the proceeding of the sol-gel formation and the curing of the coated films on Al. Based on the group frequencies as well as their spectral behavior under different conditions, vibrational assignments have been made for most of the observed bands. Surface enhanced Raman scattering has revealed the chemical adsorption of MPTMS sol-gel on silver particles. Recorded reflection and absorption infrared (RAIR) spectra of coated tiles cured at different temperatures have indicated that surface reaction may occur at high temperature. The anticorrosion characters of the coated metals have been evaluated with the measured electrochemical data. Results from cyclic voltammographs have indicated that each layer of sol-gel coating would reduce the redox current across the electrode/electrolyte solution interface. Tafel plots have shown that the anodic current of the coated electrode decreases significantly and the corrosion potentials shift to the positive side.     

Vibrational spectra of volatile inorganic hydrides in the liquid state

The results of studies of IR and Raman spectra of volatile inorganic hydrides of Group IV–VI and Periods 3 and 4 elements in the liquid state are surveyed and analyzed. The mechanisms of intermolecular interactions in these liquids are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 629–644, April, 1999.     

Vibrational frequencies and structural determinations of tetraisocyanatogermane

The normal mode frequencies and corresponding vibrational assignments of Ge(NCO)₄ are examined theoretically using the 98 set of quantum chemistry codes. Each of the vibrational modes was assigned to one of six types of motion predicted by a group theoretical analysis (Ge–N stretch, N–C–O symmetric stretch, N–C–O asymmetric stretch, N–C–O bend, Ge–N–C bend, and N–Ge–N bend) utilizing the T_d symmetry of the molecule. Uniform scaling factors were derived for each type of motion. Predicted infrared and Raman intensities are reported.     

Vibrational spectral analysis of L-lysine L-lysinium dichloride nitrate

The infrared and Raman spectra of l-lysine l-lysinium dichloride nitrate were recorded at room temperature and the vibrational assignments of the observed bands were made. The presence of both the carbonyl and ionized carboxylic groups has been identified in the title complex. The lysine and lysinium residues form a dimer through a strong OHO bond between them in the crystal. This together with the different environments has seen by the four –CH₂– groups in each skeleton cause several of the functional group wavenumbers to occur as doublets or as broad bands. Some of the forbidden modes of the nitrate group have been observed. The extensive intermolecular hydrogen bonding in the crystal was identified by the shifting of bands due to the stretching and bending modes of the various functional groups.