Color properties and non-covalent interactions in hydrated (Z)-4-(1-cyano-2-(2,4,5-trimethoxyphenyl)-vinyl)pyridin-1-ium chloride salt: Insights from experimental and theoretical studies.

The optical charge-transfer (CT) property and the crystal structure of (Z)-4-(1-cyano-2-(2,4,5-trimethoxyphenyl)vinyl)pyridin-1-ium chloride monohydrate salt (I), which belongs to an acrylonitrile family, was studied. The title salt, I, was characterized using different spectroscopy techniques and a single-crystal X-ray diffraction study combined with quantum chemical computations. The results showed that the color properties of I are determined by the CT, changes in bandgap, optical absorption, and various non-covalent interactions. The HOMO-LUMO energy gaps are 5.41 eV and 5.23 eV for the precursor and salt, respectively. It was demonstrated that π-π stacking interactions lead to the formation of intercalated dimers and donor-acceptor interactions assisted by hydrogen bonds; the dimers and interactions are different between the precursor and the salt. The cation moiety is mainly stabilized by N(1)+-H···Cl, and the anion is predominantly stabilized by strong O(1W)- H⋯ Cl- bonds as well as the hydrogen bonds with the MeO group O(2W)-H⋯O(1) and O(2W)-H⋯O(1W). The charge transfer between cation and anion moieties in the structure is established through NBO analysis.

Crystal structure of catena-poly[[cadmium(II)-di-µ2-bromido-µ2-l-proline-κ(2) O:O'] monohydrate].

In the title coordination polymer, {[CdBr2(C5H9NO2)]·H2O} n , the Cd(II) ion is coordinated by four bromido ligands and two carboxyl-ate oxygen atoms of two symmetry-related proline ligands, which exist in a zwitterionic form, in a distorted octa-hedral geometry. There is an intra-molecular N-H⋯O hydrogen bond between the amino group and the carboxyl-ate fragment. Each coordinating ligand bridges two Cd(II) atoms, thus forming polymeric chains running along the c-axis direction. The water mol-ecules of crystallization serve as donors for the weak inter-molecular O-H⋯O and O-H⋯Br hydrogen bonds that link adjacent polymeric chains, thus forming a three-dimensional structure. N-H⋯O and N-H⋯Br hydrogen bonds also occur.

Synthesis, structure, crystal growth and characterization of a novel semiorganic nonlinear optical l-proline lithium bromide monohydrate single crystal.

l-Proline lithium bromide monohydrate (LPLBM), a promising semiorganic nonlinear optical material, was synthesized and single crystals of LPLBM were grown from solution by slow evaporation technique. Single crystal X-ray structure solution reveals that the grown crystal belongs to monoclinic system with space group P21. Presence of various functional groups was identified by FT-IR and FT-Raman spectral analyses. UV-Vis-NIR spectroscopic study shows that the LPLBM crystal possesses 90% of transmittance in the range of 250-1100nm. Vickers microhardness values, the dielectric constant and dielectric loss of the LPLBM crystal were reported. Elemental analysis by energy dispersive X-ray analysis shows the presence of carbon, nitrogen, oxygen and bromine. The surface morphology of the crystal was investigated using scanning electron microscopic study. The thermal stability of the LPLBM crystal was studied from TGA and DSC analysis. Second harmonic generation efficiency of the LPLBM crystal measured by Kurtz and Perry powder technique using Nd:YAG laser is about 0.3 times that of urea.

Crystal structure of 3-amino-1-propyl-pyridinium bromide.

The title mol-ecular salt, C8H13N2 (+)·Br(-), crystallizes with two independent 3-amino-pyridinium cations and two bromide anions in the asymmetric unit (Z' = 2). In the pyridine ring, the N atom is alkyl-ated by a propyl group. The dihedral angle between the mean planes of the pyridinium ring and the propyl group is 84.84 (2)° in cation A, whereas the corresponding angle is 89.23 (2)° in cation B. In the crystal, the anions and cations are linked via N-H⋯Br and C-H⋯Br hydrogen bonds, forming chains propagating along [100].

4-Hy-droxy-1,2,6-tri-methyl-pyridinium chloride monohydrate.

In the crystal of the title hydrated mol-ecular salt, C8H12NO(+)·Cl(-)·H2O, the water mol-ecule makes two O-H⋯Cl hydrogen bonds, generating [010] zigzag chains of alternating water mol-ecules and chloride ions. The cation is bonded to the chain by an O-H⋯O hydrogen bond and two weak C-H⋯Cl inter-actions. Weak aromatic π-π stacking [centroid-centroid separation = 3.5175 (15) Å] occurs between the chains.

1-Allyl-2-amino-pyridin-1-ium bromide.

In the cation of the title salt, C8H11N2 (+)·Br(-), the dihedral angle between the planes of the pyridinium ring and the allyl group is 79.4 (3)°. In the crystal, N-H⋯Br and weak C-H⋯Br hydrogen bonds link the cations and anions, forming chains of alternating R 2 (1)(7) and R 4 (2)(8) rings, which run parallel to the c-axis direction. The crystal studied was an inversion twin with components in a 0.753 (12):0.247 (12) ratio.

4-Hy-droxy-1,2,6-tri-methyl-pyridinium bromide monohydrate.

The title salt, C8H12NO(+)·Br(-)·H2O, is isomorphous with the chloride analogue [Seethalakshmi et al. (2013). Acta Cryst. E69, o835-o836]. In the solid state, the cations, anions and water mol-ecules are inter-linked by a network of O-H⋯O, O-H⋯Br and C-H⋯Br inter-actions. The water mol-ecule makes two O-H⋯Br hydrogen bonds, generating [010] zigzag chains of alternating water mol-ecules and bromide anions. The cation is involved in two inter-molecular C-H⋯Cl inter-actions in the chloride salt, whereas three inter-molecular C-H⋯Br inter-actions are observed in the title bromide salt. This additional inter-molecular C-H⋯Br inter-action links the adjacent water and bromide zigzag chains via cationic mol-ecules. In addition, weak π-π stacking inter-actions are observed between pyridinium rings [centroid-centroid distance = 3.5664 (13) Å].

catena-Poly[[[aqua-(glycine-κO)lithium]-µ-glycine-κ(2) O:O'] bromide].

In the title coordination polymer, {[Li(C2H5NO2)2(H2O)]Br} n , the Li(+) cation is coordinated by three carboxyl-ate O atoms of zwitterionic glycine mol-ecules and by a water mol-ecule, forming a distorted tetra-hedral geometry. One of the two glycine mol-ecules bridges neighbouring complexes, forming an infinite chain parallel to the c axis. Polymeric chains are further linked by extensive hydrogen bonds involving the Br(-) anions and glycine and water mol-ecules, producing a three-dimensional network.

Glycine-phthalic acid (1/1).

In the title compound, C2H5NO2·C8H6O4, the glycine mol-ecule exists as a zwitterion (2-aza-niumyl-ethano-ate) with a positively charged amino group and a negatively charged carboxyl-ate group. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the components into layers parallel to the ab plane. The central part of each layer is composed of hydrogen-bonded glycine zwitterions, while phthalic acid mol-ecules inter-act with the zwitterions in such a way that benzene rings protrude up and down from the layer.

Neuronal glucose transporter isoform 3 deficient mice demonstrate features of autism spectrum disorders.

Neuronal glucose transporter (GLUT) isoform 3 deficiency in null heterozygous mice led to abnormal spatial learning and working memory but normal acquisition and retrieval during contextual conditioning, abnormal cognitive flexibility with intact gross motor ability, electroencephalographic seizures, perturbed social behavior with reduced vocalization and stereotypies at low frequency. This phenotypic expression is unique as it combines the neurobehavioral with the epileptiform characteristics of autism spectrum disorders. This clinical presentation occurred despite metabolic adaptations consisting of an increase in microvascular/glial GLUT1, neuronal GLUT8 and monocarboxylate transporter isoform 2 concentrations, with minimal to no change in brain glucose uptake but an increase in lactate uptake. Neuron-specific glucose deficiency has a negative impact on neurodevelopment interfering with functional competence. This is the first description of GLUT3 deficiency that forms a possible novel genetic mechanism for pervasive developmental disorders, such as the neuropsychiatric autism spectrum disorders, requiring further investigation in humans.

Crystallographic and modelling studies on Mycobacterium tuberculosis RuvA Additional role of RuvB-binding domain and inter species variability.

RuvA, along with RuvB, is involved in branch migration of heteroduplex DNA in homologous recombination. The structures of three new crystal forms of RuvA from Mycobacterium tuberculosis (MtRuvA) have been determined. The RuvB-binding domain is cleaved off in one of them. Detailed models of the complexes of octameric RuvA from different species with the Holliday junction have also been constructed. A thorough examination of the structures presented here and those reported earlier brings to light the hitherto unappreciated role of the RuvB-binding domain in determining inter-domain orientation and oligomerization. These structures also permit an exploration of the interspecies variability of structural features such as oligomerization and the conformation of the loop that carries the acidic pin, in terms of amino acid substitutions. These models emphasize the additional role of the RuvB-binding domain in Holliday junction binding. This role along with its role in oligomerization could have important biological implications.

X-ray studies of crystalline complexes involving amino acids and peptides. XLIV. Invariant features of supramolecular association and chiral effects in the complexes of arginine and lysine with tartaric acid.

The tartaric acid complexes with arginine and lysine exhibit two stoichiometries depending upon the ionization state of the anion. The structures reported here are DL-argininium DL-hydrogen tartrate, bis(L-argininium) L-tartrate, bis(DL-lysinium) DL-tartrate monohydrate, L-lysinium D-hydrogen tartrate and L-lysinium L-hydrogen tartrate. During crystallization, L-lysine preferentially interacts with D-tartaric acid to form a complex when DL-tartaric acid is used in the experiment. The anions and the cations aggregate into separate alternating layers in four of the five complexes. In bis(L-argininium) L-tartrate, the amino acid layers are interconnected by individual tartrate ions which do not interact among themselves. The aggregation of argininium ions in the DL- and the L-arginine complexes is remarkably similar, which is in turn similar to those observed in other dicarboxylic acid complexes of arginine. Thus, argininium ions have a tendency to assume similar patterns of aggregation, which are largely unaffected by a change in the chemistry of partner molecules such as the introduction of hydroxyl groups or a change in chirality or stoichiometry. On the contrary, the lysinium ions exhibit fundamentally different aggregation patterns in the DL-DL complexes on the one hand and L-D and L-L complexes on the other. Interestingly, the pattern in the L-D complex is similar to that in the L-L complex. The lysinium ions in the DL-DL complex exhibit an aggregation pattern similar to those observed in the DL-lysine complexes involving other dicarboxylic acids. Thus, the effect of change in the chirality of a subset of the component complexes could be profound or marginal, in an unpredictable manner. The relevant crystal structures appear to indicate that the preference of L-lysine for D-tartaric acid is perhaps caused by chiral discrimination resulting from the amplification of a small energy difference.

Structure of Mycobacterium tuberculosis RuvA, a protein involved in recombination.

The process of recombinational repair is crucial for maintaining genomic integrity and generating biological diversity. In association with RuvB and RuvC, RuvA plays a central role in processing and resolving Holliday junctions, which are a critical intermediate in homologous recombination. Here, the cloning, purification and structure determination of the RuvA protein from Mycobacterium tuberculosis (MtRuvA) are reported. Analysis of the structure and comparison with other known RuvA proteins reveal an octameric state with conserved subunit-subunit interaction surfaces, indicating the requirement of octamer formation for biological activity. A detailed analysis of plasticity in the RuvA molecules has led to insights into the invariant and variable regions, thus providing a framework for understanding regional flexibility in various aspects of RuvA function.

X-ray studies of crystalline complexes involving amino acids and peptides. XLIII. Adipic acid complexes of L- and DL-lysine.

The asymmetric unit of the DL-lysine complex of adipic acid [bis(DL-lysinium) adipate], 2C6H15N2O2+.C6H8O(4)2-, contains a zwitterionic singly charged lysinium cation and half a doubly charged adipate anion (the complete anion has inversion symmetry). That of the L-lysine complex (lysinium hydrogen adipate), C6H15N2O2+.C6H9O4-, consists of a lysinium cation and a singly charged hydrogen adipate anion. In both structures, the lysinium cations organize into layers interconnected by adipate or hydrogen adipate anions. However, the arrangement of the molecular ions in the layer is profoundly different in the DL- and L-lysine complexes. The hydrogen adipate anions in the L-lysine complex form linear arrays in which adjacent ions are interconnected by a symmetric O...H...O hydrogen bond.

2'-(4-Fluorophenyl)-[1,2,3]triazolo[4',5':16,17]androst-5-en-3beta-ol methanol hemisolvate.

The asymmetric unit of the title compound, C(25)H(30)FN(3)O.0.5CH(3)OH, contains four symmetry-independent steroid and two methanol molecules. The conformations of the independent steroid molecules are very similar. Intermolecular O-H.O hydrogen bonds create two independent chains, each of which links two of the independent steroid molecules plus one methanol molecule via a co-operative O-H.O-H.O-H pattern. Intermolecular C-H.O and C-H.F interactions are also observed.

16-(4-Isopropylbenzylidene)androst-4-ene-3,17-dione.

In the title compound, C(29)H(36)O(2), the outer cyclohexene ring of the steroid nucleus has a conformation that lies about half-way between a half-chair and an envelope, while the central and outer cyclohexane rings of the steroid nucleus have slightly distorted chair conformations. The steroidal cyclopentane ring adopts a 13beta,14alpha-half-chair conformation. The benzylidene moiety has an E configuration with respect to the carbonyl group on the cyclopentane ring. The dihedral angle between the mean planes of the steroid nucleus and the benzylidene moiety is 35.54 (9) degrees. The packing of the molecules is assumed to be dictated mainly by weak intermolecular C-H.O interactions.

An aza-steroidal [17,16-c]pyrazole derivative: 2'-(p-fluorophenyl)-17a-aza-2'H-pyrazolo[4',3':16,17]-D-homoandrost-4-en-3-one.

The asymmetric unit of the title compound, C(26)H(30)FN(3)O, contains two crystallographically independent molecules, the core skeletons of which have the same absolute configuration and almost identical conformations, except for differences in the orientation of the p-fluorophenyl ring. The tetrahydropyridine ring adopts a half-chair conformation, while the cyclohexenone ring has a slightly distorted envelope conformation. The cyclohexane rings have chair conformations, sometimes slightly distorted. Intermolecular N-H.O, N-H.N and C-H.F interactions and an intramolecular C-H.N interaction are observed.

16-Cyano-13alpha-(5-methyl-1,3,4-oxadiazol-2-yl)-13,16-seco-17-norandrost-5-en-3beta-yl acetate.

In the title compound, C(23)H(31)N(3)O(3), the outer cyclohexane rings have chair conformations, while the central cyclohexene ring adopts a half-chair conformation. In the solid state, intra- and intermolecular C-H.N interactions are observed.

Two androst-5-ene derivatives: 16-[4-(3-chloropropoxy)-3-methoxybenzylidene]-17-oxoandrost-5-en-3 beta-ol and 16-[3-methoxy-4-(2-pyrrolidin-1-ylethoxy)benzylidene]-3 beta-pyrrolidinoandrost-5-en-17 beta-ol monohydrate.

In the steroidal nucleus of 16-[4-(3-chloropropoxy)-3-methoxybenzylidene]-17-oxoandrost-5-en-3 beta-ol, C(30)H(29)ClO(4), (I), the outer two six-membered rings are in chair conformations, while the five-membered ring and the central six-membered ring of the steroidal nucleus adopt half-chair and envelope conformations, respectively. In 16-[3-methoxy-4-(2-pyrrolidin-1-ylethoxy)benzylidene]-3 beta-pyrrolidinoandrost-5-en-17 beta-ol monohydrate, C(37)H(54)N(2)O(3).H(2)O, (II), one C atom of one of the outer six-membered rings of the steroid nucleus and the four C atoms of the ethoxypyrrolidine ring are disordered over two sites. The five-membered ring, and the central and one of the outer six-membered rings of the steroidal nucleus exhibit distorted half-chair, chair and envelope conformations, respectively. In (I), intermolecular O-H...O hydrogen bonds link the molecules into chains via a co-operative O-H...O-H...O-H pattern. In (II), intermolecular O-H...O and O-H...N hydrogen bonds link the steroid and water molecules alternately into extended chains.

Two azasteroidal [3,2-c]pyrazole derivatives: 2'-(p-fluorophenyl)-4-azapyrazolo[4',3':2,3]-5alpha-androstan-17beta-yl acetate and 2'-(p-fluorophenyl)-4-azapyrazolo[4',3':2,3]-5alpha-androstan-17beta-ol.

In both the title aza-steroids, 2'-(p-fluorophenyl)-4-azapyrazolo[4',3':2,3]-5alpha-androstan-17beta-yl acetate, C(27)H(34)FN(3)O(2), (I), and 2'-(p-fluorophenyl)-4-azapyrazolo[4',3':2,3]-5alpha-androstan-17beta-ol, C(25)H(32)FN(3)O, (II), the tetrahydropyridine ring adopts a half-chair conformation and is considerably strained as a consequence of the presence of the fused planar pyrazole ring. In both compounds, both cyclohexane rings have chair conformations, while the cyclopentane ring has an envelope conformation. All the rings of the steroid nucleus are trans fused. In (I), intermolecular N-H.O, C-H.F, C-H.O and C-H.N interactions are observed in the solid state, while intermolecular N-H.O and O-H.N hydrogen bonds are observed in (II).