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Abstract The issue of this work focuses on development of quantitative model equations connecting experimental mass spectrometric (MS) parameters, for instance, MS intensity, of analyte peaks with thermodynamic, kinetic and diffusion parameters of the corresponding ions with their 3D molecular and electronic structures. Our more recent contribution to this field has convincingly argued that equation D = 1.3194.10 − 17. A. I 2 ¯ − (I ¯) 2 (I − I ¯ ) 2 , obtained on the base on stochastic dynamics, is applicable to electrospray ionization (ESI), collision induced dissociation (CID) and matrix–assisted laser desorption/ionization (MALDI) mass spectrometric (MS) methods, respectively. It connects MS diffusion parameters of ions with the intensities of their peaks in the MS spectrum. There has been evidenced, that experimental diffusion parameters correspond quantitatively to theoretical quantum chemical diffusion coefficients, obtained on the base on Arrhenius' formalism. If next research effort continues to confirm the validity of the shown above quantitative relation to the behavior of the MS intensity of the analyte, with respect to time, this might imply that the mass spectrometry represents not only an irreplaceable method for quantification in the analytical practice, but it provides exact experimental information about the 3D structure of the analytes. According to the latter line of research, the first aspect of this study is an experimental and theoretical MS quantification of diffusion parameters and 3D structural determination of ions of L-tryptophyl– l –tryptophan (H–Trp–Trp–OH) under ESI(+)–MS conditions. Another issue details experimentally and theoretically the process of molecular cyclization of H–Trp–Trp–OH. This aspect of the chemical reactivity of the dipeptide has provided very important insights into major reaction paths, yielding to permuted oxazolone. Taking a step into a broad application of our model relationship stated above to different areas of science, we should underline that, no doubt, the paper contributes significantly to methodological development of mass spectrometric based methods for 3D structural analysis, exploiting herein a nontrivial case of MS fragment behavior of the peptide H–Trp–Trp–OH under ESI–MS conditions. Graphical abstract Image 1 Highlights • Electrospray ionization mass spectrometry. • Diffusion parameters. • Quantum chemistry. • 3D structural analysis. • Dipeptide. [ABSTRACT FROM AUTHOR]

The crystal structures of the 1:1 proton-transfer compounds of the dipolar donor-π-acceptor compound N, N-dimethyl-4-[( E)-2-(4-pyridinyl)vinyl]aniline ( 1), also named dimethylamino-stilbazole, with 3-nitrophthalic and perchloric acids, viz. ( E)-4-[4-(dimethylamino)styryl]pyridinium 2-carboxy-3-nitrobenzoate monohydrate ( 2) and ( E)-4-[4-(dimethylamino)styryl]pyridinium perchlorate ( 3) are described. A redetermination of the structure of the parent free base 1 at 100 K is also reported. The ( E)-4-[4-(dimethylamino)styryl]pyridinium ion exhibits slight whole molecule disorder in 2 and 3. Compound 2 is the first organic salt that contains the unusual monoanion of 3-nitrophthalic acid that is deprotonated at the 1-carboxyl group. Graphical Abstract: The crystal structures of the 1:1 proton-transfer compounds of the dipolar donor-π-acceptor compound N, N-dimethyl-4-[( E)-2-(4-pyridinyl)vinyl]aniline with 3-nitrophthalic and perchloric acids, viz. ( E)-4-[4-(dimethylamino)styryl]pyridinium 2-carboxy-3-nitrobenzoate monohydrate and ( E)-4-[4-(dimethylamino)styryl]pyridinium perchlorate are described.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Electronic absorption (EAs), circular dichroic (CD), vibrational IR- and Raman-spectroscopy, nuclear magnetic resonance (NMR), electrospray ionization (ESI) and matrix assisted laser desorption/ionization (MALDI) mass spectrometry (MS) were utilized to investigate the coordination ability of bradykinin (1) with the metal ions ZnII and AgI. The experimental data were supported by the theoretical quantum chemical calculations of the electronic structures and physical properties of the isolated complexes. Since the main aim of the study is related to the design of new artificial catalysts and angiotensin converting enzyme (ACE) inhibitors, the model interactions with the active center of ACE are also designed, taking into account the coordination mode of the ZnII-ion, crystallographically determinate in the enzyme. The role of the macromolecular conformation, the enzyme cavity around the metal ion, the coordination ability of the His383.A, His353.A and Glu411.A amino acid residues, and the competitive salt-bridged processes typical for the Arg-containing ligands are discussed with a view to explain the preferred untypical C-terminus coordination mode. The data were discussed and compared with those of the angiotensin I and II (Ang-I, Ang-II). Comprehensively were described the gas-phase stabilized complex species and fragmentation modes of the complexes by the MS methods, including the imaging mass spectrometric (IMS) techniques, representing a background for the further molecular design on the base of small synthetic, semi-synthetic and naturally occurred peptides, as well as discovery of new ACE-inhibitors, since the in vivo mapping using IMS methods, provided unique opportunity for the single experiment study of the localization of molecules, including metal complexes, achievement of the important semi-quantitative, quantitative and structural information within the frame of cells, tissues, organs and whole systems. [Copyright &y& Elsevier]

Crystal structures, theoretical, and experimental physical properties of six coordination compounds of violuric and 5-sulfosalicylic acid (5SSA) with silver and potassium ions (1–6) are reported. The correlation between crystallographic data of the potassium violurate methanol solvate (2), potassium 5-sulfosalicylicilate salts (3 and 4), the redeterminated structure for the potassium violurate dihydrate (1), and the already reported complexes of silver(I) with 5SSA (5 and 6) as well as the optical properties in the condensed phase was performed using the electronic-absorption, diffuse reflectance and fluorescence spectroscopies. The vibration characteristics of the crystals were studied by solid-state Raman spectroscopy. Special attention is focused on elucidation of the specific excitation phenomena within the THz-region, allowing unambiguously defining of the metal–organic polymorphs. The physical behavior and related processes under soft electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometric conditions are elucidated by corresponding methods, including imaging mass spectrometry (MS). A discussion on the stabilization of complex species and adducts in the gas phase depending on the type of metal ion was performed, with a view to their further application as matrices in the MALDI-Orbitrap MS method. The thermal properties were elucidated using the thermogravimetric and differential scanning calorimetric methods. Quantum chemical DFT calculations of the optical properties and selected thermodynamic quantities in solid-state were performed, supporting and elucidating some of the observed phenomena. [ABSTRACT FROM PUBLISHER]

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]

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]

The novel 3-phenylpyridinium hydrogensquarate (1) has been synthesized and its structure and properties are elucidated spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR-spectroscopy, UV-spectroscopy, TGA, DSC, DTA and ESI MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data and electronic spectrum. 3-Phenylpyridinium hydrogensquarate, crystallizes in the space group P−1 and the ions in the unit cell are joined into layers by intermolecular NH⋯O＝C(Sq) bonds with bond lengths of 2.625 and 2.626 Å, respectively. Hydrogentartarates form dimers by strong O＝COH⋯OCO interactions (2.499 Å). [Copyright &y& Elsevier]

Abstract: Two novel l-lysinium hydrogensquarate monohydrate (1) and the corresponding salt of the l-lysinium dication (2) are synthesized and their structure and properties elucidated in detail spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR-spectroscopy oriented colloid suspensions in nematic host, TGA, DSC, DTA methods, positive and negative HPLC tandem mass spectrometry (ESI-MS·MS). Quantum chemical methods are used to calculate the electronic structure, vibrational data and electronic spectra. Two novel structural motifs have been obtained, isolated [(HSq−)] and tetramolecular [(H2Sq)(HSq)2(Sq)]4− anion, respectively. Preliminary second harmonic generation measurements are also performed. [Copyright &y& Elsevier]

Abstract: A distortion of the aromatic character and stabilization of the imino-form as a result of the protonation of 4-dimethylaminopyridine was established by IR-, UV- and 1H NMR-spectral analysis of 4-diaminopyridinium hydrogensquarate. Quantum chemical calculations were carried out at MP2 and B3LYP levels of theory and a 6-311++G** basis set with a view to determining the changes in geometrical parameters and IR-spectroscopic characteristics resulting from Npy protonation. Linear-dichroic IR-spectroscopy coupled with the orientation techniques of solid samples as liquid crystal suspensions and melted solid polycrystalline films was applied for the identification of the IR-bands, characteristic for the structural fragments of the neutral and imino-form of the pyridine derivative. The spectral results were compared with the structure, obtained by a single crystal X-ray analysis. The salt contains dimmers of hydrogensquarate anions and Npy protonated cations of which the former are stabilized by strong intermolecular OH…O interactions (2.552Å and 143.1(2)°). The 4-diaminopyridinium cation interacts with the anion through moderate NH…O bonds (2.729Å and 165.0(0)°). Individual cations are π–π stacked with their neighbors at a distance of 3.406Å. [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]