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Propane-1,3-diaminium squarate dihydrate, C3H12N22+·C4O42−·2H2O, 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 tetragonal crystal system (space group P4bm) with Z = 2. The squarate dianion belongs to the point group D4h and contains a crystallographic fourfold axis. The propane-1,3-diaminium dication exhibits a C2v-symmetric all-anti conformation and resides on a special position with mm2 site symmetry. The orientation of the propane-1,3-diaminium ions makes the crystal structure polar in the c-axis direction. The solid-state supramolecular structure features a triperiodic network of strong hydrogen bonds of the N—H⋯O and O—H⋯O types. [ABSTRACT FROM AUTHOR]

Type II topoisomerases (TOP2s) play a key role in altering the DNA topology by transiently cleaving both strands of a DNA duplex. Therefore, increased TOP2 activity is associated with many cancers. Herein, we present the synthesis, structural characterization, virtual screening, and structural exploration, as well as evaluation of the antiproliferative effects of two new 4-substituted 2-(5,5-dimethyl-3-styrylcyclohex-2-enylidene)malononitrile derivatives with potential application in the drug design of isoform-specific TOP2 inhibitors. Both compounds 1 and 2 were verified by ESI-TOF-MS, NMR, and single-crystal X-ray diffraction (SCXRD) analysis. Furthermore, we applied our recently proposed SCXRD/HYdrogen DEsolvation (HYDE) technology platform in order to perform molecular modeling, virtual screening, and structural exploration with 1 and 2. For this purpose, we used the crystal structure of human TOP2β complexed to DNA and the anticancer drug etoposide. Moreover, we further evaluated the antiproliferative activity of 1 and 2 on human hepatocarcinoma HepG2 cells and compared the observed effects with those of the reference hTOP2β inhibitor etoposide. Based on the obtained results, compounds 1 and 2 showed a virtually higher binding affinity (Ki HYDE values) over etoposide towards hTOP2β but lower antiproliferative activity compared to those of etoposide. [ABSTRACT FROM AUTHOR]

C10H11N3O6, monoclinic, P21/c (no. 14), a = 7.4928(12) Å, b = 14.860(3) Å, c = 11.0593(18) Å, β = 109.465(5)°, V = 1161.0(4) Å3, Z = 4, Rgt(F) = 0.0439, wRref(F2) = 0.1060, T = 300.0(2) K. [ABSTRACT FROM AUTHOR]

C10H11N3O6, monoclinic, P21/c (no. 14), a = 7.4928(12) Å, b = 14.860(3) Å, c = 11.0593(18) Å, β = 109.465(5)°, V = 1161.0(4) Å3, Z = 4, Rgt(F) = 0.0439, wRref(F2) = 0.1060, T = 300.0(2) K. [ABSTRACT FROM AUTHOR]

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 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]

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]

Abstract: The novel 3,4-diaminopyridinium hydrogentartarate dihydrate has been synthesized 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, TGA, DSC, DTA and positive and negative ESI-MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data and electronic spectra. The studied compound crystallizes in the noncentrosymmetric space group P2 1 2 1 2 1 and exhibits a 3D network with molecules linked with participation of cations, anions and solvent molecules. Hydrogentartarates form infinite chains through strong O6;OCO interaction. The effects of N1 protonation on the optical and magnetic properties of 3,4-diaminopyridine are elucidated by comparison with the data of the neutral form. [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: 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, 1H- and 13C 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 =8.0751(14), b =25.839(4), c =10.9031(15) Å, V =2141.4(6) Å3, and Z =4 (at 300(2) K). The unit cell contains four molecules of the dye, participating in weak intermolecular interactions. The cation is nearly flat with a deviation of the planarity of 5.08 (1)°. The dye investigated is the first stilbazolium iodide containing water molecule in the solid state therefore the N-dimethylamino group declines significantly from planarity, as indicated by C13ph name="sbnd" />C2n angle of 16.08°. The dye studied shows solvatochromism of 84nm in visible region and very large Stokes shift up to 253nm. The intensity of fluorescence bands strongly depends on solvent polarity. [Copyright &y& Elsevier]

• The solid-state structures of lepidine (4-methylquinoline) and three mineral acid salts are reported. • The molecules of lepidine and the lepidinium cations in the salts are π⋅⋅⋅π-stacked in the crystal structures. • N−H⋅⋅⋅Cl or N−H⋅⋅⋅O hydrogen bonding is observed in the crystal structures of the salts. The crystal and molecular structures of free-base lepidine (4-methylquinoline, 1) and the mineral acid salts lepidinium chloride (2), nitrate (3) and dihydrogen phosphate (4) are reported. Compound 1 was studied by differential scanning calorimetry and in situ capillary cryocrystallography. In the crystal structures, the molecules of free-base lepidine in 1 and the lepidinium cations in 2 – 4 are face-to-face π⋅⋅⋅π-stacked. The quinoline nitrogen atom is not involved in directional intermolecular interactions such as weak hydrogen bonds in 1. In the salts 2 – 4 , proton transfer to the quinoline nitrogen atom and N−H⋅⋅⋅Cl (in 2) and N−H⋅⋅⋅O (in 3 and 4) hydrogen bonding is observed. Hirshfeld surface analysis reveals that lepidinium salts 2 and 3 form hydrogen-bonded dimers in the crystal and confirms that the packing of 4 is dominated by hydrogen-bonded dihydrogen phosphate anion chains. [Display omitted] [ABSTRACT FROM AUTHOR]

A comparative study of the structures and spectroscopic properties of two styrylquinolinium dyes: 4-{( E )-2-[4-(dimethylamino)naphthalen-1-yl]ethenyl}-1-methylquinolinium iodide in an anhydrous (Structure I ), and monohydrate (Strucuture II ) forms and the newly synthesized dye 4-{( E )-2-[4-(dimethylamino)naphthalen-1-yl]ethenyl}-1-pentylquinolinium bromide dihydrate ( III ) has been conducted by single crystal X-ray diffraction, IR- and Raman spectroscopy, UV–Vis, steady-state and time-resolved fluorescence spectroscopy, 1 H and 13 C NMR spectroscopy, and TG/DTA analyses. The structures I , II and III belong to a monoclinic system, space groups P 2 1 / c , P 2 1 /n , and C 2 /c , respectively. In all of the crystal structures the molecules in the asymmetric unit are in an E configuration and the naphthyl and quinolinium aromatic rings are nearly planar. The angle between the mean planes of the aromatic rings is in the range 1.43–3.65°. Calculated BLA (Bond Lengths Alternation) parameters are close to the optimal. Solvatochromism in 12 organic solvents has been investigated by using absorption and emission spectroscopy. Reversal in solvatochromic behavior of the absorption spectra has been observed. The data in solutions indicate a significant charge transfer (CT) band shifting up to 84 nm, corresponding to a great molecular first hyperpolarizability values, and very large Stokes shift up to 245 nm. The average lifetime of the fluorescence of the dye III , determined from the measured data by multi-order exponential decay curve fitting as 34.71 ns in benzene and 2.98 ns in DMSO. [ABSTRACT FROM AUTHOR]