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Abstract: The novel, 1-methyl-4-[2-(4-hydroxyphenyl)ethenyl]pyridinium dihydrogenphosphate salt was synthesized and its structure and properties elucidated spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR spectroscopy (IR-LD), UV–vis spectroscopy, TGA, DSC, DTA and MS. The compound crystallizes in the monoclinic P21/c space group and exhibits a pseudo layer structure with molecules linked by strong OH⋯O–P intermolecular hydrogen bonds of length 2.593Å. The dihydrogenphosphate anions themselves form infinite chains through strong OH⋯O–P intermolecular hydrogen bonds of lengths 2.636 and 2.658Å. The crystallographic disorder of these systems and its effect on IR-LD spectra in the solid state are discussed. Solutions of different polarity show a significant CT band shift of up to 70nm, corresponding to a molecular first hyperpolarizability value. [Copyright &y& Elsevier]

Abstract: Benzamidinium d-glucuronate (1) crystallizes in the orthorhombic space group P212121 and exhibits a 3D network with molecules linked by moderate intermolecular hydrogen bonds (HNH…O(solvent) 2.993Å, HNH…OCO 2.894Å, HNH…O(cycle) 2.844Å, OH…NH2 2.931Å, OH…O(solvent) 2.894, 2.924 and 2.715Å (stronger)) with participation of cations, anions and solvent molecules. The IR-band assignment of carbohydrate moieties is elucidated by a comparison between the types and bond lengths of intermolecular interactions with participation of OH groups in d-glucuronate and linear polarized IR-(IR-LD) spectroscopic data. Experimental results are supported by theoretical ab initio calculations of benzamidinium cation and d-glucuronate anion. [Copyright &y& Elsevier]

Abstract: The hydrogensquarates of alanyl-containing dipeptides glycylalanine (H-Gly-Ala-OH) and alanylalanine (H-Ala-Ala-OH) are characterized structurally by means of quantum chemical ab initio calculations, solid-state linear-dichroic infrared (IR-LD) spectroscopy, 1H and 13C NMR data, ESI-MS, HPLC-MS/MS, TGV and DSC methods. The structures consist in positive charged peptide moiety and negative hydrogensquarate anion (HSq−), stabilizing by strong intermolecular hydrogen bonds. The theoretical and IR-LD spectroscopic data are compared with corresponding ones of zwitterion dipeptides with a view to understanding the structural and conformational changes as well as the IR-spectroscopic ones as a result of hydrogensquarates formation. The strong overlapped and complicated IR-spectroscopic bands typical for hydrogensquarates in solid-state are assigned supporting with the presented vibrational analysis of the dipeptides and of the hydrogensqauarate anion. [Copyright &y& Elsevier]

A new crystalline complex of dl -serine and squaric acid (H 2 Sq) in stoichiometric ratio 1:1 ( dl -Ser·HSq) was synthesized, isolated and structurally characterized by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2 1 /n and its structure consists of a 3D supramolecular network of hydrogensquarate anions and serinium cations directed by intermolecular hydrogen bonding interactions. The 3D network is formed by hydrogen bonds with participation of C O–OH, hydrogensquarate ion and NH 3 + group, (Sq) C O…O C (OH) (2.525 Å), – NH 3 + …O C (Sq) (2.915, 2.985 and 3.016 Å), hydroxyl group CH 2 –OH…O C (Sq) (2.739 Å), O…H–N + (3.016 Å) and (C–OH A …O C (Sq) (3.242), respectively. The structural information shows a new structural motif, a non-classic α-chain of the hydrogensquarate anions with dihedral angle between neighbouring HSq − anions 43.66°. The Raman and infrared spectra of the new crystal were measured in the 4000–50 cm −1 and 4000–400 cm −1 region frequency range respectively. The assignment of bands in infrared and Raman spectra of the crystal was performed on the basis of DFT (B3LYP) calculations, X-ray structural results and by the comparison with literature data. [ABSTRACT FROM AUTHOR]

We report the synthesis, spectroscopic and structural elucidation of two prolinamide derivatives of squaric acid, i.e. prolinamide ester amide of squaric acid ethyl ester (1) and prolinamide diamide of squaric acid dihydrate (2). Both compounds crystallize in non-centrosymmetric space groups, monoclinic P21 (1) and orthorhombic P212121 (2), respectively. For first time in the literature the crystal structure of homodiamide of amino acid amide of squaric acid is reported. The data for heterodiamides is also absent. Supramolecular zig-zag chains by hydrogen bonds of H2N–C=O⋯HNH (3.020 Å) and HNH⋯O=C(Sq) (2.972 Å) types with the participation of amide and squaric acid (Sq) fragments, –C=O–NH2 and O=C(Sq) are refined in (1). A helix supramolecular structure is formed in (2) by moderate intermolecular HNH⋯O=C(NH2) hydrogen bond with length of 2.947 Å. The two crystallographical non-equivalent water molecules stabilized the helix by interactions of types HOH⋯O=C(Sq) (2.917 Å), HOH⋯O=C(NH2) (2.899 Å), H2O⋯NH2(C=O) (2.972 Å), respectively. Optical and magnetic properties are investigated with a view to explain the correlation structure-properties of the newly synthesized molecules. [Copyright &y& Elsevier]

Abstract: The title compound was synthesized and characterized by single crystal X-ray diffraction and solid-state polarized IR-spectroscopy of oriented colloids in a nematic host. The compound crystallizes in the monoclinic space group P21/c and its structure consists of a 3D supramolecular network of tyrammonium cations, water and sulfate anions directed by intermolecular hydrogen bonding interactions. Two non-equivalent tyrammonium cations are observed with pseudo T and T trans configurations, respectively. The vibrational characteristics of the non-equivalent molecules are assigned using solid-state polarized IR-spectroscopy. The structural and spectroscopic data are compared with theoretical calculations at the MP2/6-31++G∗ level of theory and basis set using the tyrammonium cation heptahydrate as a model system. [Copyright &y& Elsevier]