5-(4-Fluoro­phen­yl)-2,2,6-trimethyl-4H-1,3-dioxin-4-one

The 1,3-dioxine ring in the title compound, C13H13FO3, is in a half-boat conformation with the methyl-bonded C atom 0.612 (2) Å out of the plane defined by the remaining five atoms

2,2,6-Trimethyl-5-[2-(4-methyl­phen­yl)ethyn­yl]-4H-1,3-dioxin-4-one

The 1,3-dioxin-4-one ring in the title compound, C16H16O3, is in a half-boat conformation with the quaternary O—C(CH3)2—O atom lying 0.546 (1) Å out of the plane defined by the remaining five atoms. The crystal structure is consolidated by C—H⋯O contacts that lead to supra­molecular layers

Crystal Structure Of 7-[(2e)-2-benzyl-idene-3-oxobut-oxy]-4-methyl-2h-chromen-2-one.

Two independent mol-ecules (A and B) comprise the asymmetric unit of the title compound, C21H18O4. There are significant conformational differences between the mol-ecules relating in particular to the relative orientation of the 3-oxo-2-(phenyl-methyl-idene)but-oxy substituent with respect to the superimposable chromen-2-one residues. To a first approximation, the substituents are mirror images; both are approximately perpendicular to the chromen-2-one fused ring system with dihedral angles of 88.50 (7) (A) and 81.96 (7)° (B). Another difference between the independent mol-ecules is noted in the dihedral angles between the adjacent phenyl and but-3-en-2-one groups of 8.72 (12) (A) and 27.70 (10)° (B). The conformation about the ethene bond in both mol-ecules is E. The crystal packing features C-H⋯O, C-H⋯π(ar-yl) and π-π [Cg⋯Cg = 3.6657 (8) and 3.7778 (8) Å] stacking inter-actions, which generate a three-dimensional network.71o222-22

Sulphur(lone pair)…π interactions with FAD in flavoenzymes

The interactions of π-systems with lone-pairs of electrons are known and have been described in biological systems, involving lone-pairs derived from metals, metalloids, sulphur, oxygen and nitrogen. This study describes a bibliographic survey of the disulphide-bound sulphur(lonepair) interactions with -systems residing in the flavin adenine dinucleotide (FAD) cofactor oxidoreductase enzymes (flavoenzymes). Thus, of the 172 oxidoreductase enzymes evaluated for gamma-S(lone pair)…π(FAD) interactions, 96 proteins (56%) exhibited these interactions corresponding; 61% of 350 the constituent monomers featured at least one gamma-S(lone pair)…π(FAD) interaction. Two main points of association between the S(lone pair) and the isoalloxazine moiety of FAD were identified, namely at the centroid of the bond linking the uracil and pyrazine rings (60% ), and the centroid of the uracil ring (37%). Reflecting the nature of the secondary structure in three prominent classes of oxidoreductase enzymes: glutathione disulphide reductases (GR; 21 proteins), trypanothione disulphide reductases (TR, 14) and sulfhydryl oxidases (SOX, 22), the approach of the gamma-S(lone-pair) to the FAD residue was to the si-face of the isoalloxazine ring system, i.e. to the opposite side as the carbonyl residue, for all GR and TR examples, and to the re-face for all SOX examples. Finally, the attractive nature of the gamma-S(lone pair)…π(FAD) interactions was confirmed qualitatively by an examination of the non-covalent interaction plots

3-Ethenyl-1-(4-methyl­phenyl­sulfon­yl)-1H-indole

Two independent but very similar mol­ecules comprise the asymmetric unit of the title compound, C17H15NO2S. The mol­ecules have L-shapes with the dihedral angles between the fused-ring system (r.m.s. deviations = 0.036 and 0.019 Å, respectively) and the benzene ring being almost the same, i.e. 82.98 (12) and 84.46 (13)°, respectively. The terminal ethenyl group is almost coplanar with the ring to which it is connected [C—C—C—C torsion angles = −173.7 (4) and −171.7 (4)°, respectively]. Supra­molecular arrays parallel to (-124) stabilized by C—H⋯O and C—H⋯π inter­actions feature in the crystal packing

Network Structure of Insurgent Groups and the Success of DDR Processes in Colombia

We argue that organizational structure of insurgent organizations influences the prospects for success in a disarmament, demobilization, and reintegration process (DDR). In concrete, we argue that more cohesive, tighter, networks have higher levels of supervision and control on its military units and increase the probability of successful DDR processes. In order to evaluate our hypotheses, we use the theory of networks to map and characterize the network structure of the United Self-Defense Forces of Colombia (AUC) and the Revolutionary Armed Forces of Colombia (FARC). Our results suggest that armed military units grouped in smaller and more isolated components on the network remilitarize with higher probability with respect to other units on the network. Also, we find that military units with high degree of centrality on the network play an important role for the risk of conflict recurrence and success in a DDR process

Spectroscopic and Theoretical Studies of Some 3-(4 '-Substituted phenylsulfanyl)-1-methyl-2-piperidones

The analysis of the IR carbonyl bands of some 3-(4 '-substituted phenylsulfanyl)1- methyl-2-piperidones 1-6 bearing substituents: NO2 (compound 1), Br (compound 2), Cl (compound 3), H (compound 4) Me (compound 5) and OMe (compound 6) supported by B3LYP/ 6-31+ G(d, p) and PCM calculations along with NBO analysis (for compound 4) and X-ray diffraction (for 2) indicated the existence of two stable conformations, i.e., axial (ax) and equatorial (eq), the former corresponding to the most stable and the least polar one in the gas phase calculations. the sum of the energy contributions of the orbital interactions (NBO analysis) and the electrostatic interactions correlate well with the populations and the vCO frequencies of the ax and eq conformers found in the gas phase. Unusually, in solution of the non-polar solvents n-C6H14 and CCl4, the more intense higher IR carbonyl frequency can be ascribed to the ax conformer, while the less intense lower IR doublet component to the eq one. the same.CO frequency trend also holds in polar solvents, that is nu(CO(eq)) < nu(CO(ax)). However, a reversal of the ax/eq intensity ratio occurs going from non-polar to polar solvents, with the ax conformer component that progressively decreases with respect to the eq one in CHCl3 and CH2Cl2, and is no longer detectable in the most polar solvent CH3CN. the PCM method applied to compound 4 supports these findings. in fact, it predicts the progressive increase of the eq/ax population ratio as the relative permittivity of the solvent increases. Moreover, it indicates that the computed.CO frequencies of the ax and eq conformers do not change in the non-polar solvents n-C6H14 and CCl4, while the.CO frequencies of the eq conformer become progressively lower than that of the ax one going from CHCl3 to CH2Cl2 and to CH3CN, in agreement with the experimental IR values. the analysis of the geometries of the ax and eq conformers shows that the carbonyl oxygen atom of the eq conformer is free for solvation, while the O-[CO]center dot center dot center dot H[o-Ph] hydrogen bond that takes place in the ax conformer partially hinders the approach of the solvent molecules to the carbonyl oxygen atom. Therefore, the larger solvation that occurs in the carbonyl oxygen atom of the eq conformer is responsible for the observed and calculated decrease of the corresponding frequency. the X-ray single crystal analysis of 2 indicates that this compound adopts the most polar eq geometry in the solid. in fact, in order to obtain the largest energy gain, the molecules are arranged in the crystal in a helical fashion due to dipole moment coupling along with C-H center dot center dot center dot O and C-H center dot center dot center dot pi(Ph) hydrogen bonds.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)MIUR (PRIN)Univ São Paulo, Inst Chem, Conformat Anal & Elect Interact Lab, BR-05513970 São Paulo, BrazilUniversidade Federal de São Paulo, UNIFESP, Inst Environm Chem & Pharmaceut Sci, BR-09972270 Diadema, SP, BrazilUniv Fed Sao Carlos, Dept Chem, BR-13565905 Sao Carlos, SP, BrazilUniv Ferrara, Dept Chem, I-44100 Ferrara, ItalyUniversidade Federal de São Paulo, UNIFESP, Inst Environm Chem & Pharmaceut Sci, BR-09972270 Diadema, SP, BrazilCAPES: 808/2009Web of Scienc

Ethyl (E)-2-methoxy­imino-2-(4-nitro­benzo­yl)acetate

The title mol­ecule, C12H12N2O6, features an E conformation about the oxime group. The methoxy­imino and ester residues are effectively coplanar with each other (r.m.s. deviation for the nine non-H atoms = 0.127 Å) and almost orthogonal [with dihedral angles of 99.44 (13) and −77.85 (13)°, respectively] to the carbonyl and nitro­phenyl groups which lie to either side of this central plane. The crystal structure is consolidated by C—H⋯O contacts