Three salts from the reactions of cysteamine and cystamine with L-(+)-tartaric acid.

Reaction between cysteamine (systematic name: 2-aminoethanethiol, C2H7NS) and L-(+)-tartaric acid [systematic name: (2R,3R)-2,3-dihydroxybutanedioic acid, C4H6O6] results in a mixture of cysteamine tartrate(1-) monohydrate, C2H8NS(+)·C4H5O6(-)·H2O, (I), and cystamine bis[tartrate(1-)] dihydrate, C4H14N2S2(2+)·2C4H5O6(-)·2H2O, (III). Cystamine [systematic name: 2,2'-dithiobis(ethylamine), C4H12N2S2], reacts with L-(+)-tartaric acid to produce a mixture of cystamine tartrate(2-), C4H14N2S2(2+)·C4H4O6(2-), (II), and (III). In each crystal structure, the anions are linked by O-H···O hydrogen bonds that run parallel to the a axis. In addition, hydrogen bonding involving protonated amino groups in all three salts, and water molecules in (I) and (III), leads to extensive three-dimensional hydrogen-bonding networks. All three salts crystallize in the orthorhombic space group P2(1)2(1)2(1).

Copper(I) complexes of 1,10-phenanthroline and heterocyclic thioamides: an experimental and theoretical (DFT) investigation of the photophysical characteristics.

A series of luminescent mixed ligand complexes of copper(I) halides with 1,10-phenanthroline and the heterocyclic thioamides pyridine-2(1H)-thione (py2SH), pyrimidine-2(1H)-thione (pymtH), 4,6-dimethylpyrimidine-2(1H)-thione (dmpymtH), 1,4,5,6-tetrahydropyrimidine-2-thione (tHpymtH), 1,3-imidazolidine-2-thione (imtH(2)) and 4,5-diphenyl-2-oxazolethiol (dpoxtH) have been synthesized and characterized. The molecular structures of two representative compounds have been established by single-crystal X-ray diffraction. The mononuclear complexes feature the metal in a distorted tetrahedral environment surrounded by the two N atoms of the chelating 1,10-phenanthroline, the thione-S atom of the thioamide, and the halogen atom. The molecular structure, the electronic and photophysical properties and the energetics of the metal-ligand interactions for [CuI(phen)(py2SH)] have been studied by means of density functional calculations.

Characterization and DNA-interaction studies of 1,1-dicyano-2,2-ethylene dithiolate Ni(II) mixed-ligand complexes with 2-amino-5-methyl thiazole, 2-amino-2-thiazoline and imidazole. Crystal structure of [Ni(i-MNT)(2a-5mt)(2)].

A series of mixed-ligand neutral nickel(II) complexes of the general formula [Ni(i-MNT)(2a-5mt)(2)] (1), [Ni(i-MNT)(2a-2tzn)(2)] (2) and [Ni(i-MNT)(Im)(2)] (3), [where i-MNT(2-)=the dianion of 1,1-dicyano-2,2-ethylenedithiolate, 2a-5mt=2-amino-5-methyl thiazole, 2a-2tzn=2-amino-2-thiazoline and Im=imidazole] were prepared and characterized with elemental analyses, spectroscopic (IR, UV-vis) methods, magnetic susceptibility, molar conductivity and cyclic voltammetry measurements. The magnetic data, the electronic spectra and the electrical conductivity measurements indicated mononuclear neutral complexes with square-planar geometry. The X-ray analysis of [Ni(i-MNT)(2a-5mt)(2)] shows the nickel atom being fourfold coordinated with the two sulfur atoms of the dithiolate (i-MNT) ligand and the endocyclic nitrogen atoms from the two 2a-5mt ring giving rise to a slightly distorted square-planar arrangement. The cyclic voltammograms of the complexes have been recorded and the corresponding redox potentials have been estimated. The DNA-binding studies of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. Both studies have shown that the complexes can bind to CT-DNA by the intercalative and the electrostatic binding mode. Competitive binding studies with ethidium bromide (EB) with fluorescence spectroscopy have also shown that the complexes exhibit the ability to displace the DNA-bound EB indicating that they can bind to DNA in strong competition with EB.

GABAergic/glutamatergic-glial/neuronal interaction contributes to rapid adaptation in pacinian corpuscles.

Pacinian corpuscles (PCs) are tactile receptors composed of a nerve ending (neurite) that is encapsulated by layers of lamellar cells. PCs are classified as primary mechanoreceptors because there is no synapse between the transductive membrane and the site of action-potential generation. These touch receptors respond in a rapidly adapting manner to sustained pressure (indentation or displacement), which until now was believed to be attributable solely to the mechanical properties of the capsule. However, evidence of positive immunoreactivity for GABA receptors on the neurite, as well as evidence for gene expression of synaptobrevin in the lamellar cells led to the hypothesis that GABAergic inhibition originating from the lamellar cells is involved in the rapid adaptation process of PCs. Electrophysiological data from isolated PCs demonstrates that, in the presence of either gabazine or picrotoxin (GABA receptor antagonists), many action potentials appear during the static portion of a sustained indentation stimulus (similar to slowly adapting receptors) and that these "static" spikes completely disappear in the presence of GABA. It was consequently hypothesized that glutamate, released by either the neurite itself or the lamellar cells, caused these action potentials. Indeed, the glutamate receptor blocker kynurenate either decreased or totally eliminated the static spikes. Together, these results suggest that GABA, emanating from the modified Schwann cells of the capsule, inhibits glutamatergic excitation during the static portion of sustained pressure, thus forming a "mechanochemical," rather than purely mechanical, rapid adaptation response. This glial-neuronal interaction is a completely novel finding for the PC.

Conformations of substituted benzophenones.

The inclination of the two aryl rings (ring twists) in a series of benzophenone molecules has been examined. For each structure the dihedral angle (between the planes of the two sets of six aromatic C atoms) relates to both the steric considerations of the single molecule and the packing forces related to the crystal structure. Six new benzophenone structures are incorporated into the study including 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (I), C(15)H(14)O(5), that appears to have the smallest reported twist angle, 37.85 (5) degrees , of any substituted benzophenone reported to date. Three further benzophenones, 4,4'-bis(diethylamino)benzophenone (II), C(21)H(28)N(2)O, 3,4-dihydroxybenzophenone (III), C(13)H(10)O(3), and 3-hydroxybenzophenone (IV), C(13)H(10)O(2), have similar ring twists [49.83 (5), 49.84 (5) and 51.61 (5) degrees , respectively] that are comparable with the value of 54 degrees found for the orthorhombic form of unsubstituted benzophenone. 4-Chloro-4'-hydroxybenzophenone (V), C(13)H(9)ClO(2), has a ring twist of 64.66 (8) degrees that is close to the value of 65 degrees found in the metastable monoclinic form of unsubstituted benzophenone and 2-amino-2',5-dichlorobenzophenone (VI), C(13)H(9)Cl(2)NO(2), has a large ring twist of 83.72 (6) degrees . Comparisons with a further 98 substituted benzophenone molecules from the Cambridge Structural Database (CSD) have been made.

Screening seeds of some Scottish plants for free radical scavenging activity.

From a consideration of ethnobotanical and taxonomic information, seeds of 45 Scottish plant species encompassing 23 different families were obtained from authentic seed suppliers. The n-hexane, dichloromethane (DCM) and methanol (MeOH) extracts were assessed, both qualitatively and quantitatively, for free radical scavenging activity in the DPPH assay. The MeOH extracts of 37 species exhibited low to high levels of free radical scavenging activity (RC50 values ranging from 2.00 to 4.7 x 10(-4) mg/mL), and Alliaria petiolata, Prunus padus and Prunus spinosa were the most potent antioxidant extracts. The DCM extracts of 17 species showed similar levels of activity, and among those, Prunus padus and Prunus spinosa extracts were the most active with RC50 values of 2.5 x 10(-4) and 5.0 x 10(-4) mg/mL, respectively. The n-hexane extracts were much less active than the MeOH and DCM extracts, and 17 species, with the exception of Glechoma hederacea (RC50 = 1.94 x 10(-4)) displayed low to moderate levels of free radical scavenging property (RC50 values ranging from 2.00 to 8.7 x 10(-3) mg/mL).

The supramolecular structure of 6-hydroxy-1,3-benzoxathiol-2-one (tioxolone).

The planar molecules of 6-hydroxy-1,3-benzoxathiol-2-one, C(7)H(4)O(3)S, are linked by extensive O-H.O and C-H.O hydrogen bonding and are further stablilized by face-to-face pi-pi interactions.

Two oxazane macrocycles.

The 20-membered ring in 1,7,11,17-tetraoxa-2,6,12,16-tetraazacycloeicosane tetrahydrochloride, C(12)H(32)N(4)O(4)(4+).4Cl(-), adopts an endo conformation, while the 18-membered ring in 1,6,10,15-tetraoxa-2,5,11,14-tetraazacyclooctadecane tetrahydrochloride, C(10)H(28)N(4)O(4)(4+).4Cl(-), lies about an inversion centre and adopts a symmetrical conformation. In the crystal structures of both compounds, the cations and chloride anions are linked by N-H...Cl hydrogen bonds into planar sheets of molecules; the sheets are linked into three-dimensional networks via C-H...Cl hydrogen bonds.

Solid state study of hydrogen bonding in dichlorophen crystals.

An X-ray crystallographic study of dichlorophen has been performed. Intramolecular hydrogen bonding is found within the molecule and intermolecular hydrogen bonding is present between molecules. The formation of dimers within the crystal lattice has been established.

4,4'-Sulfonylbis[N-(4-nitrophenylmethylene)benzenamine]: whole-molecule disorder.

The crystal structure of the title compound, C(26)H(18)N(4)O(6)S, determined from synchrotron data with a small crystal, is characterized by the presence of whole-molecule disorder. In each molecule, the two planar portions are approximately perpendicular to one another and there are short intermolecular contacts between the nitro groups.

5-chloro-2-hydroxybenzophenone, featuring O-H...O, C-H...O, C-H...pi and pi-pi interactions.

Molecules of the title compound, C(13)H(9)ClO(2), contain an intramolecular O-H...O hydrogen bond, and the two aromatic rings are inclined at 57.02 (3) degrees with respect to one another. The crystal structure is supported by C-H...O, C-H...pi and pi-pi interactions.

4-bromo-2-(hydroxymethyl)phenol: helical hydrogen bonding, R(2)(2)(12) rings and C--H...pi interactions.

Apart from the O and H atoms of the hydroxymethyl group, molecules of the title compound, C(7)H(7)BrO(2), are essentially planar. Both O atoms act as hydrogen-bond donors and acceptors, resulting in helical hydrogen bonding in the direction of the b axis and the formation of R(2)(2)(12) rings. Weaker C--H...pi interactions are also present.

A mixed crystal of imperatorin and phellopterin, with C--H...O, C--H...pi and pi-pi interactions.

The crystal structure of 9-(3-methylbut-2-enyloxy)-7H-furo[3,2-g]chromen-7-one-4-methoxy-9-(3-methylbut-2-enyloxy)-7H-furo[3,2-g]chromen-7-one (0.926/0.074), 0.926C(16)H(14)O(4)*- x 0.074C(17)H(16)O(5), is characterized by two independent imperatorin molecules in the asymmetric unit, which exhibit different side-chain conformations. A small amount of phellopterin overlaps with one of the two imperatorin molecules. The supramolecular structure is supported by C--H...O, C--H...pi and pi-pi interactions.

Supramolecular structures of 2-chloro-5-methylphenol and 4-chloro-3-methylphenol (chlorocresol).

The crystal structures of the title compounds (both C(7)H(7)ClO) are characterized by two independent molecules in each of the asymmetric units and feature O--H...O, C--H...pi and pi-pi interactions. In addition, intermolecular C--H...Cl and intramolecular O--H...Cl interactions are present in 2-chloro-5-methylphenol. For each crystal, the non-covalent interactions emphasize the different spatial environments for the two independent molecules.

Copper(I) halide complexes with 1,3-propanebis(diphenylphosphine) and heterocyclic thione ligands: crystal and electronic structures (DFT) of [CuCl(pymtH)(dppp)], [CuBr(pymtH)(dppp)], and [Cu(mu-I)(dppp)](2).

Reaction of copper(I) chloride or bromide with equimolar amounts of the diphos ligand 1,3-propanebis(diphenylphosphine) and a heterocyclic thione (L) in acetonitrile/methanol solvent afforded mononuclear complexes of the type [CuX(dppp)(L)] with the diphosphine ligand acting as a chelating ligand. In contrast, copper(I) iodide under the same conditions gave the dimeric complex [Cu(mu-I)(dppp)](2), which contains doubly bridging iodo ligands. The structures of three complexes, namely, [CuCl(pymtH)(dppp)], [CuCl(pymtH)(dppp)], and [Cu(mu-I)(dppp)](2), have been established by single-crystal X-ray diffraction. Density functional calculations at the B3LYP level of theory provided a satisfactory description of the structural, bonding, electronic, and related properties of the [CuX(PH(3))(2)] and [CuX(1,3-pdp)] (1,3-pdp = 1,3-propane-di-phosphine) complexes and their dimers along with their associations with the pyrimidine-2-thione (pymtH) ligand. The interaction of the pymtH ligand with the Cu(I) metal center in these complexes corresponds to loose associations, the computed interaction energies predicted to be about 20 kcal/mol for all complexes in the series. The bonding mechanism of the thione ligand with the Cu(I) metal centers involves both a sigma-dative and pi-back-bonding components. The coordination of the pymtH ligand is further stabilized by X...H-N bond formation being more pronounced in the chloro than in the iodo derivatives. The Cu-X bond was also found to be a composite bond involving sigma- and pi-dative bonding components. Most important is the presence of pi-type MOs delocalized over the entire four-membered Cu(mu-X)(2)Cu ring, which supports a ring current and could probably account for the nearly equivalent Cu-X bonds in the rhombus. Moreover, all [Cu(mu-X)(PH(3))(2)](2) dimers exhibit a sigma-type MO corresponding to weak Cu.Cu interactions supporting through-ring intermetallic interactions, which seems to be responsible for the stabilization of the otherwise unstable antiaromatic Cu(mu-X)(2)Cu ring.

Coordinative N-->B bond formation and hydrogen-bonded molecular ladders in 2,5-bis[(N-->B)-(2-aminoethoxy)phenylboryl]thiophene.

The molecular structure of the title compound, C(20)H(24)B(2)N(2)O(2)S, is characterized by a twofold rotation axis passing through the S atom and the midpoint of the C-C single bond in the thiophene ring. A coordinative N-->B bond is present in the boroxazolidine ring and a single N-H...O hydrogen bond [H...O 1.93 (3) A, N...O 2.829 (3) A and N-H...O 172 (2) degrees] links the molecules into a molecular ladder.