Solvent Shifts Research Articles

VBEFP/PCM: a QM/MM/PCM approach for valence-bond method and its application for the vertical excitations of formaldehyde and acetone in aqueous solution

In this paper, a combined QM/MM/PCM approach, named VBEFP/PCM, is presented for ab initio VB study with a solvent effect incorporated. In VBEFP/PCM, both short-range and long-range solvent effects are taken into account by effective fragment potential (EFP) and polarizable continuum model (PCM), respectively, while the solute molecules are described by valence bond (VB) wave function. Furthermore, VBEFP/PCM, along with VBPCM and VBEFP, is employed for the n→π* vertical excitation of formaldehyde and acetone molecules in aqueous solution. The computational results show that VBEFP/PCM can provide the appropriate solvent shifts, whereas VBPCM underestimates the solvent shifts due to its lack of short-range solvent effect. The VBEFP results strongly rely upon the description of the short-range solvent effect. To explore the role of the solute’s electronic structure in the solvent shift, resonance energy analysis during the excitation is performed. It was found that the solute’s electronic polarization plays the most important role in the solvent shift. The resonance controls the variation of the solute’s wave function during the n→* vertical excitation, which leads to the blue solvent shifts.

Laser flash photolysis study of the reactivity of β-naphthoflavone triplet: Hydrogen abstraction and singlet oxygen generation

Abstract The absorption spectra for β-naphthoflavone (1) reveal a solvatochromic red shift in polar solvents which is consistent with the π,π* character of the S0 → S1 electronic transition. The laser flash photolysis technique has been used to characterize and study the reactivity of the triplet excited state of 1. Excitation (355 nm) of degassed solutions of 1, in acetonitrile, resulted in the formation of its corresponding triplet excited state. Addition of hydrogen donors, such as 2-propanol and 1,4-cyclohexadiene, led to triplet quenching and formation of a new transient, which was assigned to the corresponding ketyl radical obtained from a hydrogen abstraction reaction by triplet 1. This ketyl radical was characterized by experiments with methylviologen. The triplet excited state of 1 was efficiently quenched by phenols and N-acetyl l -tryptophan methyl ester. In all cases new transients were formed in the quenching process, which were assigned to the corresponding radical pair resulting from an initial electron transfer from the quencher to the excited naphthoflavone, followed by a fast proton transfer. Singlet oxygen (1O2) is formed from the triplet of 1, and a quantum yield of 0.51 was measured. TDDFT calculations with implicit solvation (IEF-PCM) were used to calculate the ground state UV–vis absorption spectrum, from which the nature of the lowest energy transitions were characterized, and the triplet–triplet absorption spectrum consistent with the triplet transient generated by LFP. Excellent correlation of the calculated and experimental spectra was achieved using the conventional PBE0 hybrid functional.

Carbazole-BODIPY conjugates: design, synthesis, structure and properties.

A set of carbazole substituted BODIPYs 2a-2c were designed and synthesized by the Pd-catalysed Sonogashira cross-coupling reaction. The effects of variation in the donor strength of various carbazoles were investigated by photophysical, electrochemical and computational studies. The electronic absorption spectra of BODIPYs 2a and 2c show charge transfer bands, which show red shift in polar solvents. The BODIPYs 2a-2c are highly fluorescent in nonpolar solvents (emission from the localized state) and poorly fluorescent in polar solvents (emission from the charge transfer state). The photophysical and electrochemical studies reveal strong donor-acceptor interaction between carbazole and BODIPY and follows the order 2a > 2c > 2b. The computational calculations show good agreement with the experimental results. The single crystal structures of BODIPYs 2a-2c are reported, which exhibit interesting supramolecular interactions. The packing diagrams of 2a show a zigzag 3D structural arrangement, whereas 2b and 2c show complex 3D structural motifs.

Solvation and spectral line shifts of chromium atoms in helium droplets based on a density functional theory approach.

The interaction of an electronically excited, single chromium (Cr) atom with superfluid helium nanodroplets of various size (10 to 2000 helium (He) atoms) is studied with helium density functional theory. Solvation energies and pseudo-diatomic potential energy surfaces are determined for Cr in its ground state as well as in the y7P, a5S, and y5P excited states. The necessary Cr–He pair potentials are calculated by standard methods of molecular orbital-based electronic structure theory. In its electronic ground state the Cr atom is found to be fully submerged in the droplet. A solvation shell structure is derived from fluctuations in the radial helium density. Electronic excitations of an embedded Cr atom are simulated by confronting the relaxed helium density (ρHe), obtained for Cr in the ground state, with interaction pair potentials of excited states. The resulting energy shifts for the transitions z7P ← a7S, y7P ← a7S, z5P ← a5S, and y5P ← a5S are compared to recent fluorescence and photoionization experiments.

Simulating electrostatic effects on electronic transitions in proteins

Biopolymer fluorescence in biology and biochemistry is increasingly used for characterising equilibrium, dynamics and imaging. This is typically done by monitoring wavelength and intensity changes without necessarily knowing what causes such changes in detail. Simulations have been at the core of the considerable recent progress in improving the microscopic understanding of wavelength and quenching of fluorescence intensity in biopolymers. This review focuses on one of the most used intrinsic probes for protein behaviour, tryptophan (Trp), which is arguably now one of the best understood probes of internal structure and dynamics for proteins – despite its reputation to the contrary. In this review, we highlight selected classical molecular dynamics in combination with quantum mechanics simulations from our group and others during the past 20 years that support this view. The work includes simulations of time-dependent wavelength shifts in solvents and proteins, fluorescence-quenching rates, dielectric compensation by water, heterogeneity of quenching rates and applications to protein folding.

Theoretical study (CC2, DFT and PCM) of charge transfer complexes between antithyroid thioamides and TCNE: electronic CT transitions.

A set of representative DFT and wavefunction based theoretical approaches have been used to study ionization potentials and, predominantly, electronic charge transfer transitions in the complexes formed between TCNE as an electron acceptor and both mono and bicyclic thioamides as donors. The mentioned thioamides are of pharmacological importance due to their efficient antithyroid activity. Within a few kcal mol(-1) we have found six stable conformers for complexes with each of benzothioamides and four conformers for each of monocyclic thioamides. Present theoretical study satisfactorily shows that there is a good correspondence between the CC2/Def2-TZVPP calculated excitation energies for complexes in vacuum supplemented by the DFT solvent shifts and experiment. Present theoretical study contributes to deeper understanding of the electronic nature of the ground and excited states of the complexes with antithyroid activity.

Identification of PTSFru as the major fructose uptake system of Clostridium acetobutylicum

As a member of the saccharolytic clostridia, a variety of different carbohydrates like glucose, fructose, or mannose can be used as carbon and energy source by Clostridium acetobutylicum ATCC 824. Thirteen phosphoenolpyruvate-dependent phosphotransferase systems (PTS) have been identified in C. acetobutylicum, which are likely to be responsible for the uptake of hexoses, hexitols, or disaccharides. Here, we focus on three PTS which are expected to be involved in the uptake of fructose, PTS(Fru), PTS(ManI), and PTS(ManII). To analyze their individual functions, each PTS was inactivated via homologous recombination or insertional mutagenesis. Standardized comparative batch fermentations in a synthetic medium with glucose, fructose, or mannose as sole carbon source identified PTS(Fru) as primary uptake system for fructose, whereas growth with fructose was not impaired in PTS(ManI) and slightly altered in PTS(ManII)-deficient strains of C. acetobutylicum. The inactivation of PTS(ManI) resulted in slower growth on mannose whereas the loss of PTS(ManII) revealed no phenotype during growth on mannose. This is the first time that it has been shown that PTS(Fru) and PTS(ManI) of C. acetobutylicum are directly involved in fructose and mannose uptake, respectively. Moreover, comprehensive comparison of the fermentation products revealed that the loss of PTS(Fru) prevents the solvent shift as no butanol and only basic levels of acetone and ethanol could be determined.

Modelling solvent effects on the absorption and emission spectra of constrained cyanines with both implicit and explicit QM/EFP models

In this contribution, we have combined Time-Dependent Density Functional Theory with both implicit solvation using variations of the well-known Polarisable Continuum Model (Linear-Response, corrected Linear-Response and State-Specific schemes) and explicit solvation approaches, to investigate the solvatochromic shifts undergone by three recently synthesised dyes. These dyes, an aza-BODIPY, a BODIPY and a so-called NBO fluorophore all present excited-states developing a significant cyanine-like character, that is known to be challenging for density-based theories. Our investigation reveals dramatic influence of the selected environmental model on both the predicted sign and amplitude of the solvent shifts. The impact of solvation on the 0–0 energies and vibronic band shapes is also discussed and comparisons with experimental data are performed.

Linear Absorption and Two-Dimensional Infrared Spectra of N-Methylacetamide in Chloroform Revisited: Polarizability and Multipole Effects

The effect of solvent polarizability and multipole effects on the amide I vibrational spectra of a peptide unit is investigated. Four molecular dynamics force fields of increasing complexity for the solvent are used to model both the linear absorption and two-dimensional infrared spectra. It is observed that, at least in chloroform solution, the predicted solvent shift is considerably improved when accounting for the polarizabiltiy and multipole effects. The latter are typically connected with halogen bonding. Significant deviations are still observed for more sensitive line shape parameters such as the spectral width and line skewness. However, the findings demonstrate that previously observed deviations have an origin in the force field treatment rather than in the electrostatic mapping procedure frequently employed to simulate linear absorption and two-dimensional infrared spectroscopy.

Spectroscopy of Nitrophenolates in Vacuo: Effect of Spacer, Configuration, and Microsolvation on the Charge-Transfer Excitation Energy

In a charge-transfer (CT) transition, electron density moves from one end of the molecule (donor) to the other end (acceptor). This type of transition is of paramount importance in nature, for example, in photosynthesis, and it governs the excitation of several protein biochromophores and luminophores such as the oxyluciferin anion that accounts for light emission from fireflies. Both transition energy and oscillator strength are linked to the coupling between the donor and acceptor groups: The weaker the coupling, the smaller the excitation energy. But a weak coupling necessarily also causes a low oscillator strength possibly preventing direct excitation (basically zero probability in the noncoupling case). The coupling is determined by the actual spacer between the two groups, and whether the spacer acts as an insulator or a conductor. However, it can be difficult or even impossible to distinguish the effect of the spacer from that of local solvent molecules that often cause large solvent shifts due to different ground-state and excited-state stabilization. This calls for gas-phase spectroscopy experiments where absorption by the isolated molecule is identified to unequivocally establish the intrinsic molecular properties with no perturbations from a microenvironment. From such insight, the effect of a protein microenvironment on the CT excited state can be deduced. In this Account, we review our results over the last 5 years from mass spectroscopy experiments using specially designed apparatus on several charged donor-acceptor ions that are based on the nitrophenolate moiety and π-extended derivatives, which are textbook examples of donor-acceptor chromophores. The phenolate oxygen is the donor, and the nitro group is the acceptor. The choice of this system is also based on the fact that phenolate is a common structural motif of biochromophores and luminophores, for example, it is a constituent of the oxyluciferin anion. A presentation of the setups used for gas-phase ion spectroscopy in Aarhus is given, and we address issues of whether double bonds or triple bonds best convey electronic coupling between the phenolate oxygen and the nitro group, the significance of separating the donor and acceptor spatially, the influence of cross-conjugation versus linear conjugation, and along this line ortho versus meta versus para configuration, and not least the effect of a single solvent molecule (water, methanol, or acetonitrile). From systematic studies, a clear picture has emerged that has been supported by high-level calculations of electronically excited states. Our work shows that CC2 coupled-cluster calculations of vertical excitation energies are within 0.2 eV of experimental band maxima, and importantly, that the theoretical method is excellent in predicting the relative order of excitation energies of a series of nitrophenolates. Finally, we discuss future challenges such as following the change in absorption as a function of the number of solvent molecules and when gradually approaching the bulk limit.

Nonlinear response time-dependent density functional theory combined with the effective fragment potential method.

This work presents an extension of the linear response TDDFT/EFP method to the nonlinear-response regime together with the implementation of nonlinear-response TDDFT/EFP in the quantum-chemistry computer package GAMESS. Included in the new method is the ability to calculate the two-photon absorption cross section and to incorporate solvent effects via the EFP method. The nonlinear-response TDDFT/EFP method is able to make correct qualitative predictions for both gas phase values and aqueous solvent shifts of several important nonlinear properties.

A solvatochromic study of N-[4-(9-acridinylamino)-3-methoxyphenyl]methanesulfonamide hydrochloride: An experimental and theoretical approach

The effects of a solvent on the position of the long-wavelength electronic absorption band of N-[4-(9-acridinylamino)-3-methoxyphenyl]methanesulfonamide hydrochloride [m-AMSA.HCl], an antitumor drug, were investigated. To assess the nature of molecular interactions of protonated m-AMSA (1) with various organic solvents the solvatochromic shifts of absorption maxima (ν‾A) with (i) traditionally used bulk solvent polarity functions (Δf and F(ε, n)) and (ii) empirical scales of solvent polarity (Z, χB and ETN) were analyzed. Additionally, in order to investigate the influence of non-specific and specific solute–solvent interactions on absorption band shifts in protic solvents the multicomponent linear regression with two Kamlet–Taft’s solvatochromic parameters (π* and α) was used. The ν‾A in solvents were also obtained using theoretical calculations with the AM1-SM5.4 method and compared with experimental values. Finally, all the results show that in aprotic solvents there are general dipolarity/polarizability effects, while in protic solvents specific interactions connected with the formation of hydrogen bonds are additionally observed.

Electronic excitation spectra of molecules in solution calculated using the symmetry-adapted cluster-configuration interaction method in the polarizable continuum model with perturbative approach

A perturbative approximation of the state specific polarizable continuum model (PCM) symmetry-adapted cluster-configuration interaction (SAC-CI) method is proposed for efficient calculations of the electronic excitations and absorption spectra of molecules in solutions. This first-order PCM SAC-CI method considers the solvent effects on the energies of excited states up to the first-order with using the zeroth-order wavefunctions. This method can avoid the costly iterative procedure of the self-consistent reaction field calculations. The first-order PCM SAC-CI calculations well reproduce the results obtained by the iterative method for various types of excitations of molecules in polar and nonpolar solvents. The first-order contribution is significant for the excitation energies. The results obtained by the zeroth-order PCM SAC-CI, which considers the fixed ground-state reaction field for the excited-state calculations, are deviated from the results by the iterative method about 0.1 eV, and the zeroth-order PCM SAC-CI cannot predict even the direction of solvent shifts in n-hexane for many cases. The first-order PCM SAC-CI is applied to studying the solvatochromisms of (2,2(')-bipyridine)tetracarbonyltungsten [W(CO)4(bpy), bpy = 2,2(')-bipyridine] and bis(pentacarbonyltungsten)pyrazine [(OC)5W(pyz)W(CO)5, pyz = pyrazine]. The SAC-CI calculations reveal the detailed character of the excited states and the mechanisms of solvent shifts. The energies of metal to ligand charge transfer states are significantly sensitive to solvents. The first-order PCM SAC-CI well reproduces the observed absorption spectra of the tungsten carbonyl complexes in several solvents.

Conductor‐like screening model for relaxed excited states: Implementation in the semiempirical method MSINDO

Two approaches to treat solvent polarization and reorientation effects for excited states of molecules and surfaces have been implemented in the recently developed MSINDO-sCIS method (Gadaczek, Krause, Hintze, Bredow, J. Chem. Theory Comput. 2011, 7, 3675). They allow for an efficient calculation of analytical energy gradients and hence open the opportunity to investigate fluorescence effects or photochemical reactions in solution for large molecules that are difficult to treat with high-level methods. Both approaches are based on the conductor-like screening model (COSMO) (Klamt and Schüürmann, J. Chem. Soc., Perkin Trans. 1993, 2, 799) in combination with the configuration interaction singles (CIS) method (Foresman, Head-Gordon, Pople, and Frisch, J. Phys. Chem. 1992, 96, 135). The paper gives a brief outline of the theoretical background. As a first application, solvent shifts of three well-studied, environment-sensitive fluorescent dyes (Kucherak, Didier, Mély, and Klymchenko, J. Phys. Chem. Lett. 2010, 1, 616) have been calculated and compared with experimental results and standard time-dependent density functional theory. A statistical evaluation of MSINDO-COSMO-sCIS is provided for a set of 39 molecules suggested recently by Jacquemin et al. (Jacquemin, Planchat, Adamo, and Mennucci, J. Chem. Theory Comput. 2012, 8, 2359). Calculated vertical and adiabatic excitation energies and fluorescence energies are compared to experimental data.

Comparative study between univariate spectrophotometry and multivariate calibration as analytical tools for quantitation of Benazepril alone and in combination with Amlodipine

Four simple, accurate, reproducible, and selective methods have been developed and subsequently validated for the determination of Benazepril (BENZ) alone and in combination with Amlodipine (AML) in pharmaceutical dosage form. The first method is pH induced difference spectrophotometry, where BENZ can be measured in presence of AML as it showed maximum absorption at 237nm and 241nm in 0.1N HCl and 0.1N NaOH, respectively, while AML has no wavelength shift in both solvents. The second method is the new Extended Ratio Subtraction Method (EXRSM) coupled to Ratio Subtraction Method (RSM) for determination of both drugs in commercial dosage form. The third and fourth methods are multivariate calibration which include Principal Component Regression (PCR) and Partial Least Squares (PLSs). A detailed validation of the methods was performed following the ICH guidelines and the standard curves were found to be linear in the range of 2–30μg/mL for BENZ in difference and extended ratio subtraction spectrophotometric method, and 5–30 for AML in EXRSM method, with well accepted mean correlation coefficient for each analyte. The intra-day and inter-day precision and accuracy results were well within the acceptable limits.

NMR based solvent exchange experiments to understand the conformational preference of intrinsically disordered proteins using FG‐nucleoporin peptide as a model

The conformational preference of a peptide with three phenylalanine-glycine (FG) repeats from the intrinsically disordered domain of nucleoporin 159 (nup159) from the yeast nucleopore complex is studied. Conformational states of this FG-peptide in dimethyl sulfoxide (DMSO), a non-native solvent, are first studied. A solvent exchange scheme is designed and performed to understand how the conformational preferences of the peptide are altered as the solvent shifts from DMSO to water. An ensemble of structures of a 19-residue peptide is determined based on (13)Cα, (1)Hα, and (1)HN chemical shifts and with inter-proton distances. An experimental model is then presented where chemical shifts and amide-proton temperature dependence is probed at changing DMSO to water ratios. These co-solvent experiments provide evidence of a conformational change as the fraction of water increases by the stark change in the behavior of amide protons under varied temperature. This investigation provides a NMR based experimental method in the field of intrinsically disordered proteins to realize conformational transitions from a non-native set of structures (in DMSO) to a native set of disordered conformers (in water).

Photosensitizing properties of triplet furano and pyrano-1,2-naphthoquinones

Abstract The absorption spectra for both families of naphthoquinones reveal a solvatochromic red shift in polar solvents which is consistent with the π,π* character of the S 0 → S 1 electronic transition in all cases. The photochemical reactivity of a series of substituted furano- and pyrano-1,2-naphthoquinones has been examined by laser flash photolysis. Excitation ( λ = 355 nm or 266 nm) of degassed solutions of the quinones 1a – f and 2a – f , in acetonitrile, resulted in the formation of their corresponding triplet excited state. Addition of hydrogen donors, such as 2-propanol, toluene and methylcyclohexane led to the formation of new transients, which were assigned to the corresponding ketyl radicals derived from the hydrogen abstraction reaction by the corresponding triplets. The low values ( k q ∼ 10 5 L mol −1 s −1 ) observed for the hydrogen abstraction rate constants for the naphthoquinones using 2-propanol as the quencher led us to conclude that the triplet excited state has ππ* character. The triplet excited state of these naphthoquinones was efficiently quenched by 4-methoxyphenol and N -acetyl l -tryptophan methyl ester ( k q ∼ 10 9 L mol −1 s −1 ). In all cases a new transient was formed in the quenching process, which was assigned to the corresponding radical pair resulting from an initial electron transfer from the quencher to the excited quinone, followed by a fast proton transfer. The quantum efficiency of singlet oxygen ( 1 O 2 ) formation from the naphthoquinones was determined by employing time-resolved near-IR emission studies upon laser excitation and revealed large values in all cases, which are fully in accord with the ππ* character of these triplets in acetonitrile. Theoretical calculations (TD) DFT were used to calculate UV–vis spectra and to investigate the nature of the transition of λ max as well as to investigate the structure and reactivity of the first triplet state. The calculated triplet energies are compatible with the experimental findings and the calculated hydrogen abstraction from phenol by T 1 quinones indicates a PCET mechanism.

Classification of the Crystallization Behavior of Amorphous Active Pharmaceutical Ingredients in Aqueous Environments

To classify the crystallization behavior of amorphous active pharmaceutical ingredients (API) exposed to aqueous environments. A set of approximately 50 chemically and physically diverse active pharmaceutical ingredients (APIs) was selected for this study. Two experimental setups were employed to characterize the crystallization behavior of the amorphous API in an aqueous environment. For the first approach, precipitation, as evidenced by the development of turbidity, was induced using the solvent shift method, by mixing concentrated API solutions in DMSO with an aqueous buffer in a capillary. Subsequently, crystallization was monitored in situ over time using synchrotron radiation (simultaneous SAXS/WAXS beamline 12-ID-B at the Advanced Photon Source, Argonne National Laboratories, Argonne, IL). In the second approach, amorphous films were prepared by melt quenching; after adding buffer, crystallization was monitored with time using polarized light microscopy. In general, the crystallization behavior of a given compound was similar irrespective of the experimental method employed. However, the crystallization behavior among different compounds varied significantly, ranging from immediate and complete crystallization to no observable crystallization over biorelevant time scales. Comparison of the observed behavior with previous studies of crystallization tendency in non-aqueous environments revealed that the crystallization tendency of individual APIs was somewhat similar regardless of the crystallization environment. API properties, rather than the method by which amorphous materials are generated, tend to dictate crystallization behavior in aqueous media.

Synthesis, structure and theoretical investigation into a homoleptic tris(dithiolene) tungsten

A new homoleptic dithiolene tungsten complex, tris-{1,2-bis(3,5-dimethoxyphenyl)-1,2-ethylenodithiolene-S,S′}tungsten, was successfully synthesized via a reaction of the thiophosphate ester and sodium tungstate. The thiophosphate ester was prepared from 3,5-dimethoxybenzaldehyde via benzoin condensation to produce the intermediate 1,2-bis-(3,5-dimethoxyphenyl)-2-hydroxy-ethanone compound, followed by a reaction of the intermediate with phosphorus pentasulfide. FTIR, UV–Vis spectroscopy, 1H NMR and 13C NMR and elemental analysis confirmed the product as tris{1,2-bis-(3,5-dimethoxyphenyl)-1,2-ethylenodithiolene-S,S′}tungsten with the molecular formula of C54H54O12S6W. Crystals of the product adopted a monoclinic system with space group of P2(1)/n, where a=12.756(2)Å, b=21.560(3)Å, c=24.980(4)Å and β=103.998(3)°. Three thioester ligands were attached to the tungsten as bidentate chelates to form a distorted octahedral geometry. Density functional theory calculations were performed to investigate the molecular properties in a generalized-gradient approximation framework system using Perdew–Burke–Ernzerhof functions and a double numeric plus polarization basis set. The HOMO was concentrated on the phenyl ligands, while the LUMO was found along the W(S2C2)3 rings. The theoretical optical properties showed a slight blue shift in several low dielectric solvents. The solvatochromism effect was insignificant for high polar solvents.

Molecular structure, spectroscopic properties and DFT calculations of 2-(methylthio)nicotinic acid

The analyses of possible conformations, molecular structures, vibrational and electronic properties of 2-(methylthio)nicotinic acid molecule, C7H7NO2S, with the synonym 2-(methylsulfanyl)nicotinic acid have been first presented theoretically. At the same time, FT-IR and micro-Raman spectra of 2-(methylthio)nicotinic acid were recorded in the regions 400–4000 cm−1 and 100–4000 cm−1, respectively. In our calculations, the DFTB3LYP method with 6–311G(d, p) basis set was used to have the structural and spectroscopic data about the mentioned molecule in the ground state and the results obtained were compared with experimental values. Furthermore, gauge invariant atomic orbital (GIAO) 1H and 13C NMR chemical shifts in different solvents, UV-vis TD-DFT calculations, the highest occupied molecular orbitals (HOMO-2, HOMO-1, HOMO), lowest unoccupied molecular orbital (LUMO), molecular electrostatic potantial (MEP) surface, atomic charges and thermodynamic properties of molecule have been theoretically verified and simulated at the mentioned level. The energetic behavior of title molecule in different solvent media was investigated by using DFT/B3LYP method with 6–311G(d, p) basis set in terms of integral equation formalism polarizable continuum model (IEFPCM). In addition, the calculated infrared intensities, Raman activities, reduce masses and force constants of the compound under study have been also reported.