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The paper presented with qualitative and quantitative analysis of alkaloids in solid-state, using the excitations within the THz-spectroscopic region of 300-30 cm(-1) (9.00-0.9 THz). Series of nine plant flavonoids (FLs) and their mixtures were analyzed both qualitatively and quantitatively. For first time in the literature was reported the quantitative analysis of alkaloids and their mixtures within the THz-region using the solid-state Raman spectroscopy, and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The calibration and validation, concentration limit of detection (LOD), limit of quantification (LOQ), and linearity limit (LL) were obtained. The chemometric nonlinear and linear approaches for analysis and interpretation of the quantities were applied. The results obtained were compared with a parallel QA, using the calibrated and validated HPLC electrospray ionization (ESI) mass spectrometric method, electronic absorption (EAs) and CD spectroscopy. The metrology, including accuracy, measurement repeatability (intra-serial precision condition of measurement), measurement precision, trueness of the measurement, and reproducibility of the measurement, measurement bias and errors of the measurements were discussed., (Copyright © 2011 Elsevier B.V. All rights reserved.)

This article has been withdrawn at the request of the editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The identification and quantitative determination of sulfonamidesin solid-state as n-component mixtures is performed. The limits of detection (LODs), accuracy, precision and repeatability are obtained and discussed, using the Raman spectra within 200-30 cm(-1) region (6.00-0.9 THz). The excitations, corresponding to H-bonding deformations, lattice vibrations, as well as coupling modes are used for determination. The validation of the statistical and mathematical tools for procedure of the spectroscopic patterns is performed. The possibilities of baseline correction methods, smoothing procedures, and non-linear curve fitting method for quantitative analysis within THz-region for complex spectroscopic patterns of n-component mixtures (n=1-5) are discussed. The hybrid HPLC tandem mass spectrometry (MS/MS) and powder XRD are applied as independent physical methods for analysis of the studied systems., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Synthesis, spectroscopic and structural study of trans- and cis-(±)-3-phenyl-4-(pyrrolidine-1-carbonyl)-isochroman-1-ones is performed in order to obtain the correlation between the crystal structure and spectroscopic properties of both isomers in solid-state. The methods such as single crystal X-ray diffraction, conventional and linear-polarized IR-spectroscopy, UV-spectroscopy, mass spectrometry, ¹H and ¹³C NMR are employed. Quantum chemical ab initio and DFT calculations are performed, to support the experimental data for the electronic structure and optical properties., (Copyright © 2010 Elsevier B.V. All rights reserved.)

A series of five substituted 2-amino-5-oxonitriles, obtained by the Michael reaction have been designed, synthesised, isolated and spectroscopically and structurally elucidated by means of single crystal X-ray diffraction, linear-polarized infrared (IR-LD) and UV-spectroscopy, (1)H NMR, mass spectrometry and thermal methods. Theoretical quantum chemical calculations were carried out, thus supporting the experimental optical properties and electronic structure of compounds studied.

The conformational preference and electronic properties of three L-tryptophyl-containing dipeptides, i.e., glycyl-L-tryptophane (H-Gly-Trp-OH), L-alanyl-L-tryptophane (H-Ala-Trp-OH), and L-methionyl-L-tryptophane (L-Met-Trp-OH) in solution depending on the pH of the media are studied both theoretically and experimentally. The effect of the protonation of the COO(-) and deprotonation of the NH3+ as well as the alkaline hydrolysis of the amide fragment in a strong basic media on the electronic spectra are discussed. Ab initio and density functional theory (DFT) methods as well as the time-dependent DFT (TD-DFT) method as a function of the basis set are performed with a view to obtain the geometry and electronic properties of all of the species as well as the intermediate, obtained in the alkaline hydrolysis mechanism.

The title compound, 2-(phenylethyl)ammonium hydrogensquarate hemihydrate, was synthesized and structurally and spectroscopically characterized by a single crystal X-ray diffraction and solid-state polarized IR spectroscopy of oriented colloids in a nematic host. The crystal structure consists of two crystallographically independent 2-(phenylethyl)ammonium cations, joined in a 2D hydrogen-bonded network with hydrogensquarate anions and solvent water molecules. Surprisingly, the crystallographically non-equivalent cations exhibit differing pseudo T and G trans configurations.

The crystal structures and optical properties of the novel (1R,2R)-(-)-1,2-diammoniumocyclohexane squarate trihydrate (1) and bis(hydrogen squarate) (2) were elucidated and reported. Physical methods, single crystal X-ray diffraction, UV-vis-NIR, polarized IR spectroscopy of oriented colloids, mass spectrometry, and thermal methods were used. Quantum chemical DFT calculations were performed with a view to predict the optical and NLO properties of the systems (1) and (2). Both compounds are characterized with the noncentrosymmetric orthorhombic space groups C222(1) (1) and P2(1)2(1)2(1) (2), indicating nonlinear optical properties in the bulk. These organic salts are thermal stable up to 400 degrees C and transparent over the range from 270 to 1100 nm.

Stereo-structural analysis and IR-bands assignment of the aromatic dipeptides L-tryrosyl-L-phenylalanine (Tyr-Phe), L-phenylalanyl-L-tyrosine (Phe-Tyr) and their hydrochloride salts have been carried out by means of IR-LD spectroscopy of oriented as nematic liquid crystal suspension solid samples. The experimental data are compared with known crystallographic ones and theoretical predicted geometries at RHF/ and UHF/6-31G**.

A validation of the developed new orientation method of solid samples as suspension in nematic liquid crystal (NLC), applied in linear-dichroic infrared (IR-LD) spectroscopy has been carried out using a model system DL-isoleucine (DL-isoleu). Accuracy, precision and the influence of the liquid crystal medium on peak positions and integral absorbances of guest molecules have been presented. Optimization of experimental conditions has been performed as well. An experimental design for quantitative evaluation of the impact of four input factors: the number of scans, the rubbing-out of KBr-pellets, the amount of studied compounds included in the liquid crystal medium and the ratios of Lorentzian to Gaussian peak functions in the curve fitting procedure on the spectroscopic signal at five different frequencies, indicating important specifities of the system has been studied.

Possibilities of linear-dichroic infrared (IR-LD) spectroscopy based on oriented solid samples as suspension in nematic liquid crystal have been applied for detailed experimental IR-band assignment and structural information of 2-[5,5-dimethyl-3-(2-phenyl-vinil)-cyclohex-2-enylidene]-malononitrile, 2-[5,5-dimethyl-3-[2-(2-methoxyphenyl)vinyl]cyclo-hex-2-enylidene]malononitrile and 2-[3-[2-(2,4-dimethoxyphenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene]malononitrile. The data of last two compounds have been compared with known crystallographic ones, thus determining the validity of conclusions made.

Stereo structural characterization of methionine-containing tripeptides glycine-glycine-methionine (Gly-Gly-Met) and methionine-glycine-glycine (Met-Gly-Gly) is carried out by means of linear-dichroic infrared spectral analysis of oriented as nematic liquid crystal suspension solid samples. Thus obtained data are compared with theoretical ones received by ab initio calculations (Hartree-Fock level of theory and 6-31G** basis set). An IR-spectral characterization of both tripeptides is included as well.

As part of an investigation on the coordination ability of peptides, structural analyses of the solid di-, tri, and tetrapeptides glycyl-glycine (GG), glycyl-glycyl-glycine (GGG), glycyl-glycyl-glycyl-glycine (GGGG), and their protonated hydrochlorides glycyl-glycine.HCl (GGH), glycyl-glycyl-glycine.HCl (GGGH), and glycyl-glycyl-glycyl-glycine.HCl (GGGGH) have been carried out. The quantum chemical calculations (Hartree-Fock/6-31++G**) and linear-dichroic infrared (IR-LD) spectroscopy predict a near to linear structure of the pure ligands, but the experimental IR-LD data are in accordance with a cross-linked disposition of amide fragments in the protonated forms., (Copyright 2006 Wiley Periodicals, Inc.)

IR-spectroscopic and stereo-structural analysis of aromatic l-Tryptophan containing dipeptides l-Tryptophan-l-Tryptophan (Trp-Trp), l-Tyrosine-l-Tryptophan (Tyr-Trp) and cyclo(Trp-Trp) have been carried out by means of solid-state linear-dichroic infrared (IR-LD) spectroscopy of oriented as suspension in nematic liquid crystal solids. The experimental data have been compared with analogous ones of the simple amino acids l-Tyrosnine (l-Tyr) and l-Tryptophan (l-Trp). In cyclo(Trp-Trp), the IR-spectral changes towards the IR-ones of acyclic Trp-Trp have been determined. A theoretical analysis of Tyr-Trp at Hartree-Fock level of theory and 6-31G** basis set is also applied.

Validation of reducing-difference procedure based on subtracting of non-polarized infrared (IR) spectra of n-component solid mixtures is presented. The accuracy and precision are established. The limits of detection are 3.0, 2.5, 1.5 and 1.0wt.% for 5-, 4-, 3-and 2-component mixtures, respectively. Smoothing procedures for IR spectral analysis, based on Savitzky-Golay or Fourier methods are applied as well. The mean values and relative standard deviations for peak position (nu(i)) and integral absorbance (A(i)) obtained by this data processing approach have been examined using Student's t-test.

The conventional (non-polarized) and linear-polarized IR-spectra of 2-pyrrolidone and laurolactam as typical representatives of lactams with cis- and trans-amide configuration, respectively, were studied by means of difference IR-spectroscopy. The application of this method to treatment of the non-polarized IR-spectra permits additional conclusions about the likely self-associates of these compounds dissolved in aprotic solvents. By means of the difference linear-dichroic IR-spectroscopy, a more precise assignment of the characteristic bands of the lactam cis- and trans-peptide forms as well as their stereo structures were accomplished. A comparative analysis with the linear-dichroic IR-spectra of epsilon-caprolactam and caprylolactam, as similar compounds, with cis- and trans-conformation, respectively, was also carried out.

Stereo-structures of protonated (L)-phenylalanine ((L)-Phe), (L)-tyrosine ((L)-Tyr) and (L)-tryptophan ((L)-Trp) containing homodipeptides ((L)-Tyr-(L)-Tyr, (L)-Phe-(L)-Phe, (L)-Trp-(L)-Trp) are carried out by ab initio calculations. The obtained data in gas phase are compared with experimental ones, received by linear-dichroic infrared (IR-LD) spectroscopy of solids, oriented as suspension in nematic mesophase. An observation of a good correlation between theoretical and spectroscopic geometry parameters established and illustrated the possibilities of this complex study approach for the prediction of the stereo-structures in compounds in solid state. The protonation leads to little variance in the bond lengths and angles, expecting the COO(-) fragment, where a distortion of equalized COO(-) bond lengths, stabilizing a C=O double bond and C-O(H) one is established. Significant deviations of the dihedral angles as a result of the protonation are obtained in the skeletal aliphatic and amide- fragments. In (L)-Tyr-(L)-Tyr and (L)-Phe-(L)-Phe, a deviation of O=C-N-H torsion angle about 10-14(0) is predicted. The calculations show a trans-amide configuration in (L)-Trp-(L)-Trp and a cis-one after its protonation.

A stereo structural characterization of 2,5,6-thrimethylbenzimidazole (MBIZ) and 2-amino-benzimidaziole (2-NH(2)-BI) and their N(1) protonation salts was carried out using a polarized solid state linear dichroic infrared spectral (IR-LD) analysis in nematic liquid crystal suspension. All experimental predicted structures were compared with the theoretical ones, obtained by ab initio calculations. The C(s) to C(2v)(*) symmetry transformation as a result of protonation processes, with a view of its reflection on the infrared spectral characteristics was described.

The interaction between homocysteine (HCysSH) and Cu(II) leads to the formation of a yellow complex [Cu(I)(HCysS-SCysH)2]Cl (1) after redox processes in the Cu(II)-homocysteine system resulting in dimerization of the ligand and formation of a mononuclear Cu(I) complex with two dimers. The structure of (1) was obtained by IR-LD spectral analysis of a solid amorphous sample oriented in nematic liquid crystal medium. The original technique for orientation developed here and the polarized IR spectra thus obtained, permit the determination of the complexation sites and coordination mode of diamagnetic complexes. In the complex (1), Cu(I) is coordinated through the two O atoms of one COO- group of each of the ligands and the metal ion coordination sphere represents a distorted tetrahedron.

During the last 2 decades it was proposed that atherogenesis was closely related to the homeostasis of homocysteine (hCys) and/or copper. We hypothesized that the physiological action of hCys may be connected with its ability to form complexes with Cu. Our results showed the presence of two different Cu-hCys complexes. At a molar ratio Cu:hCys 1:1, a blue complex most probably consistent with a tentative dimeric Cu(II)(2)(hCys)(2)(H(2)O)(2) formula was formed, with tetrahedral Cu coordination and anti-ferromagnetic properties. The redox processes between Cu(II) and hCys, in a molar ratio > or =1:3 led to formation of a second yellow Cu(I)hCys complex. Both Cu-hCys complexes affected the metabolism of extracellular thiols more than hCys alone and inhibited glutathione peroxidase-1 activity and mRNA abundance. The biological action of hCys and Cu-hCys complexes involved remodeling and phosphorylation of focal adhesion complexes and paxillin. The adhesive interactions of monocytes with an endothelial monolayer led to the redistribution of both paxillin and F-actin after all treatments, but the diapedesis of monocytes through endothelial cell monolayer was both greater and faster in the presence of the tentative Cu(II)(2)(hCys)(2)(H(2)O)(2) complex. Together, these observations suggest that Cu-hCys complexes actively participate in the biochemical responses of endothelial cells that are involved in the aethiopathogenesis of atherosclerosis.