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Different solid state forms of the research chemical fasoracetam, which counters the effects of Alzheimer's disease, have been subjected to a thermal and structural analysis. Single crystals were obtained from solution evaporation and from the melt. Single-crystal X-ray analyses of the crystals show the existence of 2 hydrated and 1 non-hydrated crystalline form of fasoracetam. Under ambient conditions, the hydrate form I is found to be the most stable form, showing a melting point of 57C. This low melting point, combined with possible water losses could cause problems when formulating the hydrated form and impact the storage conditions of the compound., (Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

The structure of four hydroxamic acids (HA) that show antifungal activities in complexes with several metals is revealed by single crystal diffraction. The structures of HA with C2, C6, C10, and C12 hydrocarbon chains are reported. The smallest member of the series, N-hydroxyacetamide (HA2), crystallizes in the centrosymmetric space group P21/c while those with longer chain lengths N-hydroxyhexanamide (HA6), N-hydroxydecanamide (HA10), and N-hydroxydodecanamide (HA12) crystallize in the space group P21, and display remarkable packing. [ABSTRACT FROM AUTHOR]

Abstract: Direct access to the protonated merocyanine forms of two substituted spiropyrans by mechanosynthesis or sonochemistry was explored. The compounds were formed by the condensation reaction of the methyleneindolium iodide salt with salicylaldehyde derivatives. X‐ray crystallography, 1H NMR spectroscopy, ab initio geometry optimization, and absorption spectroscopy were combined to provide a better understanding of the four‐state molecular switch system in which the newly synthesized protonated merocyanines were found to play a central role. The results of this study suggest that the stability of the protonated merocyanines requires acidic conditions, as treatment with base led to the corresponding unprotonated merocyanines, which in turn spontaneously converted into photochromic closed spiropyrans. [ABSTRACT FROM AUTHOR]

A novel series of HgII coordination polymers with a general formula [HgL(N)3]n·n(solv) (HL = 2-pyridinecarbaldehyde isonicotinoylhydrazone; n(solv) = 0.5H2O (1), 2MeOH (2), EtOH (3), PrOH (4) and 0.5BuOH (5)) was prepared and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. The crystal structure of HL, elucidated by X-ray diffraction, comprises two independent molecules in the asymmetric unit cell, each of which is stabilized by an intramolecular hydrogen bond formed between the carbohydrazide hydrogen atom and the 2-pyridyl nitrogen atom. Crystal structures of 1–5 each reveal a similar 1D zigzag metal–organic chain [HgL(N)3]n, where the organic ligands bridge metal centers. These chains are extended into distinct 2D supramolecular nets by strong hydrogen bonds with the solvent molecules and/or short Hg…N supramolecular contacts. These networks were topologically classified as the hcb in 1 and fes in 2–5 underlying nets. On comparing the H-bonding patterns, it can be concluded that the lattice water molecules in 1 and methanol molecules in 2 form H-bonding interactions with the O and amide N atoms of L in the former structure and the O atom of L in the latter structure. In the remaining coordination compounds, the lattice solvent prefers the azide N atom for H-bonding. Furthermore, the existence of Hg…N interactions in 2–5 and their absence in 1 clearly highlights the importance of the size and polarity of the solvents on the self-assembly generation of HgII coordination polymers. A broad network of intermolecular π…π stacking interactions, formed between the pyridyl fragments, provide further reinforcement of crystal packing patterns in the structures of HL and 2–5. DFT based charge and energy decomposition scheme (ETS-NOCV) was applied to characterize the obtained polymers. [ABSTRACT FROM AUTHOR]

In this work, crystal structures of commercially available photochromic compounds, i.e., spiropyrans and spirooxazines, were investigated by single-crystal X-ray diffraction. A total of five new structures were obtained via isothermal evaporation experiments under different conditions, namely 1,3,3-Trimethylindolino-benzopyrylospiran (I), 1,3,3-Trimethylindolinonaphtospirooxaxine (II), 1-(2-Hydroxyethyl)-3,3-dimethylindolino-60-nitrobenzopyrylospiran (III), and 1,3,3-Trimethylindolino-80-methoxybenzopyrylospiran (IVa and IVb). Since the basic structure of a spiropyran/-oxazine does not present typical hydrogen bond accepting and donating groups, this study illustrates the importance of additional functional groups connected to this kind of molecules to induce specific intermolecular interactions. Our results show that possible hydrogen bonding interactions are rather weak due to the high steric demand of these compounds. These results are supported by a search of the Cambridge structural database focused on related structures. [ABSTRACT FROM AUTHOR]

The reaction of neat 3-chloroaniline with neat S=C=N–P(O)(OPh)2 leads to a new N-phosphorylated thiourea, 3-ClC6H4NHC(S)NHP(O)(OPh)2 (1). The same reaction in non-dried CH2Cl2 or C6H6 leads to the salt-like compounds [3-ClC6H4NH3]+[NCS]− (2) and [3-ClC6H4NH3]+[P(O)2(OPh)2]−·0.5C6H6 (3·0.5C6H6), respectively, while using non-dried acetone yields 1-(3-chlorophenyl)-4,4,6-trimethyl-3,4-dihydropyrimidine-2(1H)-thione (4). Dissolution of 1 in non-dried CH2Cl2, C6H6 or Me2C=O leads to the direct formation of 2, 3·0.5C6H6 and 4, respectively. It was established that thione 4 is most likely formed through the thiourea 1-assisted aldol condensation of acetone leading to mesityl oxide. In turn the latter ketone interacts with 1 followed by its hydrolysis leading to 4. Compounds 1–4 have been characterized by NMR spectroscopy and elemental analysis and their molecular structures were elucidated by X-ray diffraction. Hirshfeld surface analysis showed that the structures of both 1 and 4 are mainly characterized by H…H, H…C, H…Cl and H…S contacts as well as by H…O in the structure of 1. The enrichment ratio, derived as the decomposition of the crystal contact surface between pairs of interacting chemical species, for 1 was found, as expected for the polar contacts, which are generally hydrogen bonds, to be significantly larger than unity for the contacts of the type H…O and H…S. A much larger than unity value was found for the enrichment ratio of the C…C contacts in the structure of 1, which is due to extensive π…π stacking in the crystal packing. The enrichment ratio for 4 was found to be larger than unity for the contacts of the type H…C and, but with a lesser degree, H…Cl and H…S. [ABSTRACT FROM AUTHOR]

Reaction of 5-phenyl-2,2′-bipyridine (L) with a mixture of CuI or [Cu(CH3CN)4]BF4 and PPh3 leads to mononuclear heteroleptic complexes [CuL(PPh3)I] (1) and [CuL(PPh3)2]BF4 (2). According to X-ray diffraction, L crystallizes in the monoclinic space group P21/n, exhibiting a disorder over four orientations. Complexes 1 and 2 crystallize in the monoclinic space groups P21/c and P21, respectively. 1 comprises a discrete neutral molecule, while 2 has an ionic structure containing [CuL(PPh3)2]+ and BF4–. Both structures reveal that each tetracoordinated copper(i) atom is linked to two nitrogen atoms of L, one iodide and one PPh3 in the structure of 1, or two PPh3 in the structure of 2 with the formation of a distorted tetrahedral coordination core. The structure of 2 is additionally stabilized by a weak intramolecular π…π stacking interaction formed between two adjacent phenyl rings of two PPh3 ligands. Hirshfeld surface analysis showed that the structures of both complexes are mainly characterized by H…H and C…H contacts as well as by I…H in the structure of 1 and F…H in the structure of 2. The 2D fingerprint plots of two different molecules in the structure of L showed that both molecules exhibit contacts for π…π stacking interactions. The factors important for the stability of 1 and 2 were further quantitatively and qualitatively characterized by the charge and energy decomposition method ETS-NOCV. According to diffuse reflectance spectroscopy in the solid state, free L exhibits bands exclusively in the UV region, while the spectra of 1 and 2 also contain bands in the visible range up to about 500 and 600 nm. All three compounds were found to be emissive in the solid state. DFT calculations have shown that, while emission of L is due to the ligand-centered π→π* transition, luminescence of 1 and 2 was assigned to a (M + X)LCT and MLCT excited states, respectively. [ABSTRACT FROM AUTHOR]

The N-phosphorylated thiourea iPrNHC(S)NHP(O)(OPh)2 (HL) has been synthesized by the reaction of iPrNH2 and (PhO)2P(O)NCS. Recrystallization of HL from aqueous acetone leads to [iPrNH3]+[P(O)2(OPh)2]− in a quantitative yield. Reaction of the deprotonated HL with NiCl2 leads to violet [NiL2] crystals with a 1,3-N,S-coordination mode of the ligands. Static DFT and ab initio molecular dynamics studies indicated that [NiL2] is stabilized predominantly by intramolecular N–H…O=P hydrogen bonding and dynamically by secondary CPh–H…S interactions. All compounds have been characterized by IR, diffuse reflectance, UV-vis and NMR spectroscopy, single crystal X-ray diffraction analysis and elemental analysis. Thermal properties investigated in an air atmosphere by means of TGA revealed a residue corresponding to NiPS3. [ABSTRACT FROM AUTHOR]

Abstract: A new cyclosilicate hydrate with composition (C6H14N)4·[Si8O16(OH)4]·12H2O was crystallized and the structure determined by single-crystal X-ray diffraction. The structure, described by the tetragonal space group I41/a, with unit cell dimensions of a =39.2150(2)Å and c =14.1553(2)Å, contains columns of hydrogen-bonded cubic octamer silicate anions. The space between silicate columns holds hydrogen-bonded water and protonated hexamethyleneimine molecules compensating the negative charge of the silicate. The crystal water can be removed resulting in a rearrangement of the columns into orthorhombic symmetry. Removal of the organic moiety causes amorphisation. Flash evacuation results in a new microporous material with pore volumes typical of a zeolite. [Copyright &y& Elsevier]

New gallium(III) and iron(III) endohedral complexes were obtained from a hemicryptophane ligand bearing suitable binding sites for octahedral metal coordination. The solid-state structures of the free host and of the complexes were determined by single-crystal X-ray diffraction analysis. The metal ion is linked to the hydrazone nitrogen and the phenolate oxygen atoms, yielding a distorted octahedral geometry around the encapsulated metal. The two isomorphous structures of the metal complexes reveal the exclusive formation of PΔ/MΛ enantiomeric pairs. [ABSTRACT FROM AUTHOR]

The N-phosphorylated thiourea iPrNHC(S)NHP(O)(OPh)2 (HL) has been synthesized by the reaction of iPrNH2 and (PhO)2P(O)NCS. Recrystallization of HL from aqueous acetone leads to [iPrNH3]+[P(O)2(OPh)2]− in a quantitative yield. Reaction of the deprotonated HL with NiCl2 leads to violet [NiL2] crystals with a 1,3-N,S-coordination mode of the ligands. Static DFT and ab initio molecular dynamics studies indicated that [NiL2] is stabilized predominantly by intramolecular N–H…O=P hydrogen bonding and dynamically by secondary CPh–H…S interactions. All compounds have been characterized by IR, diffuse reflectance, UV-vis and NMR spectroscopy, single crystal X-ray diffraction analysis and elemental analysis. Thermal properties investigated in an air atmosphere by means of TGA revealed a residue corresponding to NiPS3. [ABSTRACT FROM AUTHOR]

Abstract: In this Letter we report on the reaction of 4H-cyclopenta[2,1-b:3,4-b′]dithiophen-4-one with various trivalent organophosphorus derivatives, with an emphasis on the final products depending on the applied reagents. No reaction occurred upon treatment with either triphenyl- or tricyclohexylphosphine, whereas addition of triethyl phosphite or tri(n-butyl)phosphine resulted in pinacol rearrangement. Structure elucidation of the isolated 5H-spiro(benzo[1,2-b:6,5-b′]dithiophene-4,4′-cyclopenta[2,1-b:3,4-b′]dithiophen)-5-one was achieved by combined NMR experiments, theoretical chemical shift and geometry calculations, and single crystal X-ray analysis. [Copyright &y& Elsevier]