N-[4-Acetyl-5-isobutyl-5-(2-p-tolyl­prop­yl)-4,5-dihydro-1,3,4-thia­diazol-2-yl]acetamide ethyl acetate hemisolvate

The racemic title compound, a new terpenoid, C20H29N3O2S·0.5C4H8O2, was synthesized from Cedrus Atlantica essential oil. The compound crystallizes with a disordered ethyl acetate solvent mol­ecule. The thia­diazole ring is almost planar, with a maximum deviation from the mean plane of 0.015 (2) Å for the C atom connected to the isobutyl group and has a puckering amplitude of 0.026 (2) Å. The dihedral angle between the benzene and thia­diazole rings is 18.32 (8)°. The crystal packing involves inter­molecular N—H⋯O hydrogen bonds

N-[4-Acetyl-5-methyl-5-(2-p-tolyl­prop­yl)-4,5-dihydro-1,3,4-thia­diazol-2-yl]acetamide

The title heterocyclic compound, C17H23N3O2S, was synthesized from 4-(4-methyl­cyclo­hex-3-en­yl)pent-3-en-2-one, which was isolated from Cedrus atlantica essential oil. The thia­diazole ring adopts a flattened envelope conformation, with the flap sp 3-hybridized C atom lying 0.259 (1) Å out of the plane of the other four atoms. The screw-related mol­ecules are linked into chains along the b axis by inter­molecular N—H⋯O hydrogen bonds

N-[4-Acetyl-5-(2-methylprop-1-enyl)-5-(2-p-tolyl­prop­yl)-4,5-dihydro-1,3,4-thia­diazol-2-yl]acetamide

The title heterocyclic compound, C20H27N3O2S, was synthesized from 2-(4-methyl­cyclo­hex-3-en­yl)-6-methyl­hepta-2,5-dien-4-one, which was isolated from the essential oil Cedrus atlantica. The thia­diazole ring is essentially planar [maximum deviation 0.006 (2) Å] and it forms a dihedral angle of 18.08 (9)° with the benzene ring. The dihedral angle between the thia­diazole ring and the acetamide plane is 7.62 (10)°. In the crystal, mol­ecules are linked into chains running along the c axis by inter­molecular N—H⋯O hydrogen bonds

(3S,4S,5S,10S,13R,14R,17R)-4 alpha,14 alpha-Dimethyl-3 beta-tosyl-5 alpha-ergost-8-ene-7,11,24-trione at 100 K

The title compound, C36H50O6S, forms an extended sheet of four fused rings which exhibit different conformations, as already observed in previously reported triterpene structures. There are weak intra- and intermolecular C-(HO)-O-... inter-actions. A weak C-Hc pi interaction also occurs, involving the tosyl group

Charge density and electrostatic potential analyses in paracetamol

International audienceThe electron density of monoclinic paracetamol was derived from high-resolution X-ray diffraction at 100 K. The Hansen– Coppens multipole model was used to refine the experimental electron density. The topologies of the electron density and the electrostatic potential were carefully analyzed. Numerical and analytical procedures were used to derive the charges integrated over the atomic basins. The highest charge magnitude (À1.2 e) was found for the N atom of the paracetamol molecule, which is in agreement with the observed nucleophilic attack occurring in the biological media. The electric field generated by the paracetamol molecule was used to calculate the atomic charges using the divergence theorem. This was simultaneously applied to estimate the total electrostatic force exerted on each atom of the molecule by using the Maxwell stress tensor. The interaction electrostatic energy of dimers of paracetamol in the crystal lattice was also estimated

Low-temperature (100 K) crystal structures of pentaaqua(5-nitro salicylato) complexes of magnesium(II), zinc(II), cobalt(II) and nickel(II): A pi-pi stacked and hydrogen bonded 3D supramolecular architecture

Reactions of metal chloride or sulfate and the sodium salt of 5-nitrosalicylic acid (5-nsa) in aqueous solution result in isomorphous complexes of type [M(H2O)(5)(5-nsa)](+) (5-nsa)(-) center dot H2O [M = Mg (1), Zn (2), Co (3), Ni (4)] in the solid state. Structural analyses of these compounds reveal that the cationic moiety is a monomeric complex in which the metal is coordinated by five aqua ligands and one carboxylato O-atom from the 5-nitrosalicylato ligand, forming a slightly distorted octahedron. The crystal packing exhibits ionic parts assembled through extensive hydrogen bonding. The metal-bonded cationic moiety and the non-ligating anionic one are also engaged in pi-stacking interactions which contribute to the crystal cohesion. The anchoring of the individual ionic subunits through pi-pi stacking and hydrogen bonding results in a 3D supramolecular architecture

Experimental electron density and electrostatic potential analysis of zinc(aspirinate) 2 (H 2 O) 2 complex A 3d 10 metal bonding to a drug ligand

International audienceFor the protection against the side effects and the improvement of the pharmacological activity of nonsteroidal antiinflammatory drugs (NSAID's), one alternative way is to design a metal complex of these agents. In this context, we have investigated the electrostatic properties of the zinc-aspirinate dihydrate (Zn[C 9 H 7 O 4 ] 2 (H 2 O) 2 ) complex to characterize and to mimic the activity of this potent pharmaceutical compound. A high-resolution X-ray diffraction experiment at 100 K has been performed on the Zn[C 9 H 7 O 4 ] 2 (H 2 O) 2 complex which crystallizes in the C2/c space group displaying a tetrahedrally coordinated zinc atom. The Hansen-Coppens multipole model was used to derive the experimental electron density to study the chemical bonding and the metal-ligand charge transfer. The investigation of the electron density has revealed that only the Zn 4s orbital participates in the metal-ligand interaction whereas the metal 3d full valence shell remains unperturbated. The κ-model refinement yielded a zinc net charge of +1.3 e with a highly contracted 4s electronic shell. The most positive charge of the aspirinate ligand was found on the acetyl carbon (+0.8 e), in agreement with the previously observed nucleophilic attack on the aspirin drug in the inhibited cyclooxygenase (COX) enzyme channel. The electrostatic potential was calculated from the multipole populations and the net atomic charges derived from the X-ray diffraction data. This fundamental property was carefully analyzed through the 3D isopotential and molecular surface representations to highlight the active sites of the zinc-aspirinate complex

Experimental electron density of Zn-aspirinate complex: the subtlety of a 3d10 metal bonding to a drug-ligand

International audienceThe design of metal-drug complexes is of a particular interest in the pharmacological researches. Metal combinations with pharmaceutical agents are known to improve the drug activity and to decrease the toxicity. The metal itself can be pharmacologically active (Cu) or can even regulate enzyme metabolism (Zn, Mg). Non-steroidal anti-inflammatory drugs (NSAID's), like aspirine derivatives, have a large spectrum in the therapy of common infections. NSAID's are also known to produce in vivo serious gastro-intestinal complications when the drug molecules are used alone. Therefore, the bonding interaction between the metal and the drug-ligand is an essential step in the understanding of further predictive biochemical enzyme inhibitions. In this study, the electron density distribution of Zn-aspirinate complex (Zn[C9O5H9)H2O]2) is derived from multipole refinements (Hansen-Coppens model) of accurate 100 K diffraction data (up to sinq/l = 1.15 Å-1). 81909 equivalent reflections were collected on a Siemens CCD diffractometer (MoKa radiation). The data processing yields an internal factor Rint = 4,07% and 5082 unique data (I>3s(I)) which are used in the refinements. The title compound crystallizes in monoclinic C2/c centrosymmetric space group. The crystal structure exhibits a monodentate aspirinate ligand (Zn-O(acid group) = 1.996(1) Å, Zn-O(H2O) = 2.019(1) Å). Zn atom is tetrahedrally coordinated to two water molecules and to two oxygen atoms of two drug-ligands. The experimentally electron density obtained in the Zn-O bonds is discussed with respect to a hypothetical metal orbital hybridization (3d, 4s). The electrostatic potential is also calculated from the atomic multipole populations