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The structure of a mononuclear Au(III) complex of the dipeptide glycyl-S-serine (Gly-Ser) has been predicted using solid-state linear dichroic IR (IR-LD) spectroscopy, based on an orientation technique in a nematic liquid crystal suspension. Results are compared with data from 1H- and 13C-NMR, MS, elemental analysis, thermogravimetry and differential scanning calorimetry. The metal ion is coordinated as a tridentate through NH2, N (from deprotonated amide) and O (COO-) groups to form [Au(C5H9N2O4)Cl], with the fourth position of the square-planar coordination sphere being completed by a Cl- ion. [ABSTRACT FROM AUTHOR]

A solid state, linear dichroic IR analysis of a mononuclear Au(III) complex of the tripeptide glycylmethioninylglycine (GlyMetGly) oriented in a nematic liquid crystal has been carried out. Structural results are compared with 1 H and 13 C NMR data. The ligand coordinates to Au(III) as a tridentate in [Au(C 9 H 17 N 3 O 4 S)Cl]Cl 2 , binding through S, and the N- and O-atoms of neighbouring CONH– and COO - groups. The fourth position is occupied by a terminal Cl - ligand. [ABSTRACT FROM AUTHOR]

Abstract: 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 (ν i ) and integral absorbance (A i ) obtained by this data processing approach have been examined using Student''s t-test. [Copyright &y& Elsevier]

A new mononuclear Cu(II) complex of 4-aminopyridine (4AP), [Cu(4AP)4]Cl2·2CH3OH ( 1 ), was obtained and structurally characterized by single-crystal X-ray diffraction methods. The complex is square-planar involving four monodentate 4AP molecules coordinated through the Npy atoms. A solid-state linear-dichroic spectroscopic analysis (IR-LD) as a suspension in a nematic liquid crystal was carried out over the 4000–400?cm -1 range and determined stereochemical parameters compared crystallographic data. Detailed IR characteristics are reported. [ABSTRACT FROM AUTHOR]

Interaction between the S-Phe–S-Phe dipeptide (PP) and Au(III) leads to the formation of a yellow complex, [Au(PP)Cl3]Cl (1), with monodentate coordination of the dipeptide with Au(III) through one O atom of the COO - group. Three Cl - anions bond to the metal center as terminal ligands. The structure of 1 was obtained by comparative solid-state linear-dichroic infrared (LD-IR) spectroscopic analysis of a solid sample and the pure dipeptide S-Phe–S-Phe, both oriented in a nematic liquid crystal suspension. [ABSTRACT FROM AUTHOR]

Mononuclear Au(III) complexes of the peptides H-His-Met-OH (D) and H-Gly-Gly-Met-OH (T) and their N -protected forms Ac-His-Met-OH (Ac-D) and Ac-Gly-Gly-Met-OH (Ac-T) were structurally characterized by means of IR, MS and NMR. In the complexes with dipeptides [AuLCl 2 ]Cl (L = D or Ac-D), Au(III) is coordinated through S and imidazole N atoms from methionine and histidine fragments of the ligands forming macrochelate rings at mol ratio Au : L = 1 : 1. Additionally, Au(III) is coordinated by two terminal chloride ions in a square-planar arrangement. In complexes with the tripeptides [AuL′Cl] (L′ = T or Ac-T), however, the metal ion is coordinated in a tridentate fashion, through S and two N atoms, also at mol ratio M : L = 1 : 1. The fourth position of Au(III) is occupied by a Cl - ligand. [ABSTRACT FROM AUTHOR]

Abstract: A linear dichroic infrared (IR-LD) spectral analysis of solid 4-aminopyridine (4-AP) samples was carried out using two orientation techniques, i.e., as polycrystalline layers and in a nematic mesophase. The so-called reducing-difference procedure was used for the polarized IR-spectra interpretation. By achieving a more precise assignment of a part of the 4-AP characteristic frequencies, the obtained data proved a Fermi-resonance splitting of the symmetrical NH2-stretch and confirmed the predominant aromatic character of the pyridine ring. The possibilities of the difference IR-LD technique used for the study of the supramolecular solid-state structure are also illustrated. [Copyright &y& Elsevier]

The article presents information on the structure of the organic compound S-Phenyl 4-cyanothiobenzoate or C14H9NOS. The molecules of this compound exhibit a chiral non-planar structure in which the 4-cyanophenyl and S-phenyl rings are tilted at dihedral angles of 1.81 (2) and 72.49 (1)° with respect to the central thiocarbonate unit. The compound crystallizes in the non-centrosymmetric monoclinic space group P21 and participates in very weak intermolecular hydrogen bonds and its observed structure is in good agreement with those determined for other S-phenyl thiobenzoates.

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