217 research outputs found
2-[(4-Chlorophenyl)selanyl]-3,4-dihydro-2H-benzo[h]chromene-5,6-dione: crystal structure and Hirshfeld analysis
The title organoselenium compound, C19H13ClO3Se {systematic name: 2-[(4-chlorophenyl)selanyl]-2H,3H,4H,5H,6H-naphtho[1,2-b]pyran-5,6-dione}, has the substituted 2-pyranyl ring in a half-chair conformation with the methylene-C atom bound to the methine-C atom being the flap atom. The dihedral angle between the two aromatic regions of the molecule is 9.96 (9)° and indicates a step-like conformation. An intramolecular Se...O interaction of 2.8122 (13) Å is noted. In the crystal, π–π contacts between naphthyl rings [inter-centroid distance = 3.7213 (12) Å] and between naphthyl and chlorobenzene rings [inter-centroid distance = 3.7715 (13) Å], along with C—Cl...π(chlorobenzene) contacts, lead to supramolecular layers parallel to the ab plane, which are connected into a three-dimensional architecture via methylene-C—H...O(carbonyl) interactions. The contributions of these and other weak contacts to the Hirshfeld surface is described
Homoleptic [ONO]2Ti(IV) type complexes of amino-acid-tethered phenolato, Schiff-base ligands: Synthesis, characterization, time-resolved fluorescence spectroscopy, and cytotoxicity against ovarian and colon cancer cells
Six homoleptic Ti(IV) compounds of dianionic tridentate Schiff base ligands were synthesized from chiral amino acids, 2-hydroxybenzaldehyde and Ti(OiPr)4. The
compounds were spectroscopically characterized and the molecular geometries were established by X-ray crystallography. The ligands coordinated the titanium via
carboxylate-O-, imine-N-, and phenoxide-O atoms. Two isomers were identified; each based on a trans-N2O4 donor set, but one with trans carboxylate-O atoms and another with each carboxylate-O atom trans to a phenoxide-O atom. Photophysical profiles exhibited faster excited-state relaxation in the solid phase than in solution.
Marked cytotoxicities were recorded toward human ovarian A2780 and colon HT-29 cancer cells with IC50 values ranging between 23±2 and 103±3 µM. Comparative hydrolytic stability studies by NMR in 10% D2O solutions provided t1/2 values of up to 15±2 h, with little correlation to cytotoxicity implying a role of hydrolysis products in the reactivity and identifying steric bulk as a contributor to stability and solubility
5-Methyl-2,4-bis(methylsulfanyl)tricyclo[6.2.1.02,7]undeca-4,9-diene-3,6-dione1
The structure analysis of the title compound, C14H16O2S2, shows the SMe and H atoms of the bond linking the six-membered rings to be syn and also to be syn to the bridgehead –CH2– group. Each of the five-membered rings adopts an envelope conformation at the bridgehead –CH2– group. The dione-substituted ring adopts a folded conformation about the 1,4-C⋯C vector, with the ketone groups lying to one side. The cyclohexene ring adopts a boat conformation
1,3-Bis(4-bromophenyl)imidazolium chloride dihydrate
In the title hydrated salt, C15H11Br2N2
+·Cl−·2H2O, the complete imidazolium cation is generated by a crystallographic twofold axis, with one C atom lying on the axis. The chloride ion and both water molecules of crystallization also lie on a crystallographic twofold axis of symmetry. The cation is non-planar, the dihedral angle formed between the central imidazolium and benzene rings being 12.9 (3)°; the dihedral angle between the symmetry-related benzene rings is 25.60 (13)°. In the crystal, O—H⋯Cl hydrogen bonds result in supramolecular chains along c mediated by eight-membered {⋯HOH⋯Cl}2 synthons. These are consolidated by C—H⋯O and π–π [centroid–centroid distance = 3.687 (3) Å] interactions
Crystal structure of tert-butyl 2-(hydroxymethyl)-5-{4-[(methoxycarbonyl)amino]phenyl}-2,5-dihydro-1H-pyrrole-1-carboxylate, C18H24N2O5
Synthesis, structural characterisation and theoretical studies of a novel pyridazine derivative: Investigations of anti-inflammatory activity and inhibition of α-glucosidase
X-ray crystallography on pyridazine 1 (ethyl 2-(3-methyl-4-(4-methylbenzyl)-6-oxopyridazin1(6H)-yl)acetate) shows the planar pyridazinyl ring to exhibit significant delocalisation of πelectron density over the constituent atoms and to be substituted with oxo, methyl, (4-
methylphenyl)methyl and N-bound ethylacetate groups. While three of the ring-bound atoms are close to co-planar with the ring, the ethylacetate group is not; the latter exhibits a definitive kink in its conformation. In the molecular packing of 1, helical supramolecular
chains along the b-axis are formed through O- and N-methylene-C–H…O(carbonyl) and Omethylene-C–H…π(pyridazinyl) interactions. The chains are connected into a supramolecular layer by π(pyridazinyl)…π(phenyl) interactions. The flat layers stacks along the c-axis
2 without directional interactions between them. The geometry-optimisation of 1 resulted in the straightening of terminal ethylacetate group but no other substantial changes. Computational chemistry shows the most stabilising interactions in the crystal are due to the
π(pyridazinyl)…π(phenyl) (-10.7 kcal/mol) followed by O- and N-methylene-C–H…O(carbonyl) (-9.5 and -9.0 kcal/mol, respectively). The most prominent identified interlayer interaction is a weak methylene-C–H···N(pyridazinyl) contact. Throughout, comparisons are made with the phenyl analogue of 1, namely 2. Most notably, the lattice
energy of 1 is approximately 4.1 kcal/mol more stable than that of 2, an observation related to the influence upon the molecular packing exerted by the methyl substituent of 1. Compound 1 exhibits moderate inhibition against α-glucosidase, compared to Acarbose, and weak heatinduced haemolysis inhibition
Kryptoracemates
Racemic crystals normally crystallise in centrosymmetric spacegroups containing equal numbers of enantiomers. More rarely, racemates may crystallise in non-centrosymmetric space-groups having glide symmetry or, even more rarely, in space-groups devoid of a centre of inversion, having no rotary-inversion axes nor glide plane. The latter class of crystals form the subject of the present bibliographic review – a survey of kryptoracemic behaviour. The term kryptoracemic alludes to the presence of a hidden or non-crystallographic centre of inversion between two molecules that might otherwise be expected to crystallise in an achiral space-group, often about a centre of inversion. Herein, examples of molecules with stereogenic centres crystallising in one of the 65 Sohncke space-groups are described. Genuine kryptoracemates, i.e. crystals comprising only enantiomorphous pairs are described followed by an overview of non-genuine kryptoracemates whereby the crystal also contains other species such as solvent and/or counterions. A full range, i.e. one to six, stereogenic centres are noted in genuine kryptoracemates. Examples will also be described whereby there are more that one enantiomeric pair of molecules in the crystallographic asymmetric unit. A more diverse range of examples are available for non-genuine kryptoracemates. There are unbalanced species where in addition to the enantiomeric pair of molecules, there is another enantiomeric molecule present. There are examples of genuine co-crystals, solvated species and of salts. Finally, special examples will be highlighted where the counterions are
chiral and where they are disparate, both circumstances promoting kryptoracemic behaviour
CRYSTAL STRUCTURE OF ZIG-ZAG POLYMERIC TRI-n-BUTYLTIN(IV) 3,4-METHYLENEDIOXYPHENYLACETATE
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