Crystal structure of propane-1,3-diaminium squarate dihydrate.

Propane-1,3-diaminium squarate dihydrate, CHN ·CO ·2HO, results from the proton-transfer reaction of propane-1,3-di-amine with squaric acid and subsequent crystallization from aqueous medium. The title compound crystallizes in the tetra-gonal crystal system (space group 4) with = 2. The squarate dianion belongs to the point group and contains a crystallographic fourfold axis.

Crystal structure of 1,2,3,4-tetra-hydro-isoquinolin-2-ium (2,3)-3-carb-oxy-2,3-di-hydroxy-propano-ate monohydrate.

The crystal structure of 1,2,3,4-tetra-hydro-isoquinolin-2-ium (2,3)-3-carb-oxy-2,3-di-hydroxy-propano-ate monohydrate, CHN·CHO ·HO, at 115 K shows ortho-rhom-bic symmetry (space group 222). The hydrogen tartrate anions and solvent water mol-ecules form an intricate diperiodic O-H⋯O hydrogen-bond network parallel to (001). The tetra-hydro-isoquinolinium cations are tethered to the anionic hydrogen-bonded layers through N-H⋯O hydrogen bonds.

Comparing the crystal structures and spectroscopic properties of a -hydroxy styrylquinolinium dye with those of its -dimethylamino analogue.

Two previously synthesized styrylquinolinium dyes, namely ()-1-butyl-4-(4-(dimethylamino)styryl)quinolinium iodide () and ()-1-butyl-4-(4-hydroxystyryl)quinolinium iodide (), were compared in terms of their properties by single-crystal X-ray diffraction (XRD), Hirshfeld surface analysis, Fourier transform Raman (FT-Raman), Fourier transform infrared (FT-IR), fluorescence, and ultraviolet-visible (UV-Vis) spectroscopy, and H- and C-NMR methods. Both dyes and crystallized in the triclinic and monoclinic systems in the centrosymmetric space groups -1 and 2, respectively. The unit cell of contains two molecules of the dye, participating in weak intermolecular interactions, whereas that of contains four formula units.

Pyridin-4-ylmethanaminium perchlorate mono-hydrate.

Pyridin-4-ylmethanaminium perchlorate monohydrate (synonym: 4-picolyl-ammonium perchlorate monohydrate), CHN ·ClO ·HO, crystallizes in the monoclinic system (space group 2/) with the asymmetric unit comprising two formula units (' = 2). All mol-ecular entities are located on general positions. The two crystallographically distinct 4-picolyl-ammonium cations exhibit different conformations.

Exascale applications: skin in the game.

As noted in Wikipedia, refers to having 'incurred risk by being involved in achieving a goal', where ' is a synecdoche for the person involved, and is the metaphor for actions on the field of play under discussion'. For exascale applications under development in the US Department of Energy Exascale Computing Project, nothing could be more apt, with the being exascale applications and the being delivering comprehensive science-based computational applications that effectively exploit exascale high-performance computing technologies to provide breakthrough modelling and simulation and data science solutions. These solutions will yield high-confidence insights and answers to the most critical problems and challenges for the USA in scientific discovery, national security, energy assurance, economic competitiveness and advanced healthcare.

Preparation and spectral properties of europium hydrogen squarate microcrystals.

A simple scheme for preparation of europium hydrogen squarate octahydrate microcrystals, Eu(HSq)·8HO is demonstrated. The microcrystalline powders obtained have a potential application as non-centrosymmetric and UV radiation - protective hybrid optical material. The site-symmetry of the Eu - ion is C or lower, obtained from diffuse reflectance spectra.

Predictors of laparoscopic simulation performance among practicing obstetrician gynecologists.

Background: While simulation training has been established as an effective method for improving laparoscopic surgical performance in surgical residents, few studies have focused on its use for attending surgeons, particularly in obstetrics and gynecology. Surgical simulation may have a role in improving and maintaining proficiency in the operating room for practicing obstetrician gynecologists.

Objective: We sought to determine if parameters of performance for validated laparoscopic virtual simulation tasks correlate with surgical volume and characteristics of practicing obstetricians and gynecologists.

Synthesis, crystal structure, and spectroscopic properties of new stilbazolium salt with enlarged π-conjugated system.

A new stilbazolium dye 4-{(E)-2-[4-(dimethylamino)naphthalen-1-yl]ethenyl}-1-methylquinolinium iodide monohydrate (DANSQI) having enlarged π-conjugated system was synthesized and characterized by X-ray diffraction, IR, Raman, UV-Vis, Fluorescence, (1)H- and (13)C NMR spectroscopy. Quantum chemical calculations were performed to obtain electronic structure and vibrational data, using DFT. The crystals are monoclinic, space group P21/n, with a=8.

2-(Phenylethyl)ammonium hydrogensquarate hemihydrate: crystal structure, solid-state IR-spectroscopic and theoretical characterization.

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.

Crystal structure and spectroscopic elucidation of 3-phenylpyridinium hydrogensquarate.

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.

Synthesis, spectroscopic and structural elucidation of 1-butyl-4-[2-(3,5-dimethoxy-4-hydroxyphenyl)ethenyl)]pyridinium chloride tetrahydrate.

The novel chloride salt of 1-butyl-4-[2-(4-hydroxyphenyl)ethenyl)]pyridine (1), has been synthesized as the tetrahydrate and its structure and properties elucidated in detail spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR-spectroscopy, UV-spectroscopy and mass spectrometry. Quantum chemical calculations were performed with a view to supporting and explaining the experimental structural and spectroscopic data. The compound (1) crystallizes in triclinic P1 space group and its unit cell contains two independent 1-butyl-4-[2-(3,5-dimethoxy4-hydroxyphenyl)ethenyl)]pyridinium] cations, differing with respect to the butyl chain torsion angle for which values of 80.

N,N-Diethyl-N'-[(E)-4-pyridylmethylene]benzene-1,4-diamine: a combined X-ray and density functional theory study.

The crystal structure of the title compound, C16H19N3, comprises neutral molecules of a dipolar Schiff base chromophore. A density functional theory (DFT) optimized structure at the B3LYP/6-31G(d) level is compared with the molecular structure in the solid state. The compound crystallizes in the noncentrosymmetric space group Pna2(1) with a herring-bone packing motif and is therefore a potential candidate for nonlinear optical effects in the bulk.

New Au (III), Pt (II) and Pd (II) complexes with pentapeptide glycyl-glycyl-(L)-methyonyl-glycyl-glycine and their interaction with calf thymus DNA.

The three new Au (III), Pt (II) and Pd (II) complexes with pentapeptide glycyl-glycyl-(L)-methyonyl-glycyl-glycine have been synthesized, isolated, and spectroscopically and structurally elucidated in solution and in the solid-state. Solid-state linear-dichroic infrared (IR-LD) spectroscopy of oriented colloids in a nematic liquid crystal host, (1)H- and (13)C-NMR, TGA and DSC, UV-VIS spectroscopy, EPR, ESI- and FAB- mass spectrometry and HPLC tandem mass spectrometry (HPLC-MS/MS) have been used. Quantum chemical calculations and molecular modelling were carried out in order to determine the structures and spectroscopic properties of the ligand, the newly synthesised metal complexes and their interactions with calf thymus DNA.

1,10-Phenanthrolinium hydrogensquarate monohydrate--a non-centrosymmetric structure from two non-chiral agents.

The novel hydrogensquarate salt of 1,10-phenanthroline has been synthesized, isolated and structurally elucidated by single crystal X-ray diffraction. 1,10-Phenanthrolinium hydrogensquarate monohydrate (1) crystallizes in the non-centrosymmetric P2(1) space group. Its hydrogensquarate anions form a stable dimer by means of ((Sq))OHc.

Self-assembly of hydrogensquarates: crystal structures and properties.

The self-assembly of the hydrogensquarates is elucidated by means of linear-polarized infrared (IR-LD) spectroscopy of oriented colloids in nematic host and the so-called reducing-difference procedure for polarized IR-LD spectra interpretation. The scopes and limitation are discussed on five novel derivatives of squaric acid and its anions, that is, 2-chloro-3-aminopyridinium hydrogensquarate (1), bis (1,2,3,4-tetrahydroquinolinium) squarate (2), bis hydrogensquarate dihydrate salt of 4-(aminomethyl)pyridine (3), N-(2-ammoniumethyl)-piperazinium monohydrate hydrogensquarate squarate (4), and 3-nitropyridinium hydrogensquarate monohydrate (5), respectively. The structures of these compounds 1-5 were solved by means of single-crystal X-ray diffraction, and the crystallographic data were used for the experimental elucidation of the corresponding IR spectra of crystals with respect to studying Fermi-resonance (FR), Davydov splitting (DS), and Fermi-Davydov (FD) as well as Evans' hole effects.

Hydrogensquarates of 3-nicotinoyl and 3-isonicotinoyl coumarin--crystal structures and spectroscopic elucidation.

Two novel hydrogensquarates of 3-nicotinoyl (1) and 3-isonicotinoyl (2) coumarin have been synthesized and their structures and properties elucidated spectroscopically and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR-spectroscopy, UV-spectroscopy and negative ESI MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data and electronic spectra. The IR-spectroscopic elucidation is carried out by a comparison with the characteristics of corresponding neutral 3-nicotinoyl and 3-isonicotinoyl coumarins.

N-methylcodeinium iodide--crystal structure and spectroscopic elucidation.

The correlation between the structure and the spectroscopic properties of N-methylcodeinium iodide (1) has been studied, using the methods of single crystal X-ray diffraction, IR-LD spectroscopy of oriented samples as a suspension in nematic liquid crystals, UV-vis spectroscopy and 1H and 13C NMR spectroscopy. HPLC tandem mass spectrometry (HPLC ESI MS/MS) and thermal methods were also employed. Quantum chemical calculations have been performed with a view to obtaining the electronic structure and vibrational properties of the title compound.

Polarized spectroscopic elucidation of N-acetyl-L-cysteine, L-cysteine, L-cystine, L-ascorbic acid and a tool for their determination in solid mixtures.

Method of linear polarized vibrational (both IR- and Raman) spectroscopy of oriented colloids in nematic host is applied on N-acetyl-L-cysteine, L-cysteine, L-cystine and L-ascorbic acid with a view to obtain experimental bands assignment and local structural elucidation in solid-state. Structural results are compared with available crystallographic data for all of the systems studied. Scopes and limitations of the polarized method are shown.

Stabilization of neutral NH2-R-COOH form of the antihypertensive peptides L-Valyl-L-Prolyl-L-Proline and L-Isoleucyl-L-Prolyl-L-Proline.

Spectroscopic and structural elucidation of the peptides L-Valyl-L-Prolyl-L-Proline (1) and L-Isoleucyl-L-Prolyl-L-Proline (2) are reported on the basis of experimental linear-polarized IR-spectroscopy in solid-state, 1H-NMR data and DFT. Curiously, the experimental data shown that both peptides stabilized in solution and in solid-state neutral H2N-R-COOH form. Conformational analysis made, shown two strong intramolecular NH2-O=C-N(Amide) and O=C-OH-NH2 hydrogen bonds with lengths of 2.

Crystal structures and spectroscopic properties of ester amide and diamide of squaric acid with prolinamide.

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).

Spectroscopic and structural elucidation of amino acid derivatives and small peptides: experimental and theoretical tools.

This mini review deals with the modern aspects of the spectroscopy and structural elucidation of amino acid derivatives and small biologically active compounds. Free peptide bond rotation in these systems yields various conformers, which possess differing biological activities. Another phenomenon is the intermolecular or intramolecular stacking observed in aromatic small peptides.

Esters of 1-coumarinylbenzylphosphonic acid-IR-spectroscopic and theoretical elucidation.

The IR-spectroscopic properties of three esters of 1-coumarinylbenzylphosphonic acid are elucidated both in solution and in solid-state. Linear-polarized IR-spectroscopy of oriented colloid suspensions in nematic host is used for experimental IR-characteristic band assignment in solid-state. Theoretical quantum chemical DFT calculations at B3LYP level of theory and 6-31++G** basis set are carried.

L-Leucinamide hydrogensquarate: spectroscopic and structural elucidation.

The hydrogensquarate [LeuNH(2)] (HSq) of L-leucinamide has been synthesized and its structure has been determined by single crystal X-ray diffraction. A three dimensional network is formed by hydrogen bonds with participation of the O=C-NH(2) function, the hydrogensquarate ion and the N(+)H(3) group [NH(2)..

Structural and spectroscopic elucidation of tetrapetide glycyl-(L)-prolyl-glycyl-glycine and its hydrogensquarate.

The IR-spectroscopic and structural elucidation of tetrapeptide glycyl-(L)-prolyl-glycyl-glycine and its hydrogensquarate was performed by employing linear-polarized IR-spectroscopy of oriented colloid suspensions in nematic host as well as mass spectrometry. Quantum-chemical ab initio calculations were carried out in order to evaluate both the electronic structure and optical properties of the compound studied.

Structural elucidation, optical, magnetic and nonlinear optical properties of oxystyryl dyes.

Structure, magnetic and optical properties of tetraphenylborate salts of 2,5-[1-methyl-4-[2-(4-hydroxyphenyl)ethenyl]piridinium]-propane and butane are performed in gas and condense phase by means of solution and solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids in nematic liquid crystal suspension, UV-vis and fluorescence methods, HPLC tandem ESI mess spectrometry (MS/MS), (1)H, (13)C and (1)H-(1)H COSY NMR, TGV and DSC methods. Quantum chemical DFT calculations are used for performing of the structures, optical and nonlinear optical properties of the studied compounds.