Structural modifications leading to changes in supramolecular aggregation of thiazolo3, 2-apyrimidines: Insights into their conformational features

The compounds, 7-methyl-3,5-diphenyl-5H-thiazolo3,2-apyrimidine-6-carboxylic acid ethyl ester (1), 3-amino-2-cyano-7-methyl-5-phenyl-5H-thiazolo3,2-apyrimidine-6-carboxylic acid methyl ester (2), 2-dimethylaminomethylene-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-thiazolo3,2-apyrimidine-6-carboxylic acid ethyl ester (3), 2-(3-cyano-benzylidene)-5-(4-hydroxy-phenyl)-7-methyl-3-oxo-2,3-dihydro-5H-thiazolo3,2-apyrimidine-6-carboxylic acid methyl ester; with N,N-dimethyl-formamide (4) and 3-ethoxycarbonylmethyl-5-(4-hydroxy-3-methoxy-phenyl)-7-methyl-5H-thiazolo3,2-apyrimidine-6-carboxylic acid methyl ester (5) have been synthesized and their structures evaluated crystallographically. Compound 1 crystallizes in the space group PI with Z=8, with four molecules in the asymmetric unit. Compound 2 also crystallizes in the space group PI with Z=4 wherein asymmetric unit accommodates two molecules. Compound 3 belongs to P21/c with Z=4, compound 4 crystallizes in Pbc2 1 with Z=4 and compound 5 belongs to PI with Z=2. In all the above compounds, the aryl ring positioned at C5 of thiazolopyrimidine ring is almost perpendicular. In the case of compounds with substituted phenyl ring, aryl group-up conformation predominates. However, for compounds with unsubstituted phenyl ring, aryl group-down conformation is adopted. By varying the substituents at positions C2, C3, C6 and on the aryl at C5 in the main molecular scaffold of (1-5), we have observed significant differences in the intermolecular interaction patterns. The packing features of the compounds are controlled by C-H...O, C-H...N, N-H...N O-H...N, C-H...� and �...� weak interactions. © 2014 Indian Academy of Sciences

Crystal structure of ethyl 6-(2-fluorophenyl)-4-hydroxy-2-sulfanylidene-4- trifluoromethy1-1,3-diazinane-5-carboxy late

In the title compound, C14H14F4N2O3S, the central di­hydro­pyrimidine ring adopts a sofa conformation with the C atom bearing the 2-fluoro­benzene ring displaced by 0.596 (3) Å from the other five atoms. The 2-fluoro­benzene ring is positioned axially and bis­ects the pyrimidine ring with a dihedral angle of 70.92 (8)°. The mol­ecular conformation is stabilized by an intra­molecular O-H...O hydrogen bond, generating an S(6) ring. The crystal structure features C-H...F, N-H...S and N-H...O hydrogen bonds, which link the mol­ecules into a three-dimensional network

2-4-(Trifluoromethyl) phenyl-1Hbenzimidazole

In the title compound, C14H9F3N 2, the mean planes of the benzimidazole ring system and the trifluoromethyl-substituted benzene ring form a dihedral angle of 30.1 (1)-. In the crystal, molecules are linked by N-Hâ¯N hydrogen bonds into chains along 010. Weak C-Hâ¯F hydrogen bonds and a weak C-Hâ¯-interaction connect the chains into a twodimensional network parallel to (001)

Synthesis of nanocrystalline TiO2 thin films by liquid phase deposition technique and its application for photocatalytic degradation studies

A transparent, high purity titanium dioxide thin film composed of densely packed nanometer sized grains has been successfully deposited on a glass substrate at 30°C from an aqueous solution of TiO2-HF with the addition of boric acid as a scavenger by liquid phase deposition technique. From X-ray diffraction measurement, the deposited film was found to be amorphous and turns crystalline at 500°C. The deposited film showed excellent adherence to the substrate and was characterized by homogeneous flat surface. TiO2 thin films can be used as a photocatalyst to clean up organohalides, a class of compound in pesticides that pollute the ground water. Photocatalytic degradation experiments show that indanthrene golden orange dye undergoes degradation efficiently in presence of TiO2 thin films by exposing its aqueous solution to ultraviolet light. The suitable surface structure and porosity increases the photocatalytic activity. It was also observed that hemin doped TiO2 thin films break up organohalides at a surprisingly high rate under visible light

Methyl 4-(4-hydroxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4- tetrahydropyrimidine-5-carboxylate

In the title mol­ecule, C13H14N2O3S, the di­hydro­pyrimidine ring is in a flattened sofa conformation, with the methine C atom forming the flap. The dihedral angle between the mean plane of the five essentially planar atoms of the di­hydro­pyrimidine ring [maximum deviation = 0.056 (4) Å] and the benzene ring is 89.4 (2)°. The O atom of the carbonyl group is in a trans conformation with respect to the C=C bond of the di­hydro­pyrimidine ring. In the crystal, N-H...O and O-H...S hydrogen bonds connect mol­ecules, forming a two-dimensional network parallel to (001)

Crystal structure of ethyl 5-(3-fluoro-phen-yl)-2-[(4-fluoro-phen-yl)methyl-idene]-7-methyl-3-oxo-2H,3H,5H-[1,3]thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate.

In the title mol-ecule, C23H18F2N2O3S, the pyrimidine ring is in a half-chair conformation and the 3-fluoro-phenyl group is in the axial position. The thia-zole ring (r.m.s. deviation = 0.0252 Å) forms dihedral angles of 84.8 (7) and 9.6 (7)° with the 3-fluoro-substituted and 4-fluoro-substituted benzene rings, respectively. In the crystal, weak C-H⋯F and C-H⋯O hydrogen bonds connect mol-ecules, forming zigzag chains along the b axis. In addition π-π stacking inter-actions with a centroid-centroid distance of 3.7633 (9) Å connect these chains into ladders via inversion-related 4-fluoro-phenyl groups

Effects of Ni doping on photocatalytic activity of TiO(2) thin films prepared by liquid phase deposition technique

The TiO(2) thin films doped by Ni uniformly and non-uniformly were prepared on glass substrate from an aqueous solution of ammonium hexa-fluoro titanate and NiF(2) by liquid phase deposition technique. The addition of boric acid as an F(-) scavenger will shift the equilibrium to one side and thereby deposition of the film is progressed. The rate of the reaction and the nature of deposition depend on growing time and temperature. The resultant films were characterized by XRD, EDAX, UV and SEM. The result shows that the deposited films have amorphous background, which becomes crystalline at 500 degrees C. The EDAX data confirms the existence of Ni atoms in TiO(2) matrix. XRD analysis reveals the peaks corresponding to Ni but no peak of crystalline NiO was found. The transmittance spectra of Ni uniformly and non-uniformly doped TiO(2) thin films show 'blue shift and red shift', respectively. Ni-doped TiO(2) thin films can be used as photocatalyst for the photodegradation of methyl orange dye. It was found that, organic dye undergoes degradation efficiently in presence of non-uniformly Ni-doped TiO(2) thin films when compared to uniformly doped films and pure TiO(2) films under visible light. The photocatalytic activity increases with increase in the concentration of Ni in case of nonuniformly doped thin films but decreases with the concentration when uniformly doped thin films were used

Self-assembly of cis- and trans-cyclic-1,2-diols. Supramolecular synthon equivalence between cis-1,2-diols and primary amides

Inspite of the fact that the self-assembly of compounds containing hydroxyl group has been enormously documented in the literature, our studies with aliphatic cyclic diols have offered the unique opportunity to examine the self-assembly of gauche and anti forms of ethylene glycol. Whereas the cis-diols are found to form dimers that infinitely assemble further to yield tapes, the anti-diols are found to form linear chains that link up further to yield molecular tapes. Notably, both the isomers lead to molecular tapes, which have attracted immense attention since the inception of self-assembly for controlling molecular organization. Quite remarkably, the self-assembly observed with cis-diols establish a formal equivalence between supramolecular synthons associated with cis-1,2-diols and primary amides. Although the assembly of diols is akin to the tape structure adopted by primary amides, we prefer to view the association of diols as a ladder. The structures of 5-cis and 8-cis are both step-ladder assemblies. That formed by 5-trans is a new variant termed as rope-ladder assembly. The ring motifs observed in the crystal packing suggest for further scope in exploiting the polyhydroxyl compounds for self-assembly in a predictive manner

Synthesis and crystal structure analysis of 2-(4-fluorobenzyl)-6-phenylimidazo2,1-b1,3,4thiadiazole and its chlorophenyl derivative

Preparations of 2-(4-fluorobenzyl)-6-phenylimidazo2,1-b1,3,4thiadiazole (3a) and its chlorophenyl derivative (3b) are described. Preliminary analysis was done spectroscopically by means of 1H NMR, 13C NMR spectra, mass spectra and elemental analyses. Further the structures were confirmed by X-ray crystal structure analyses. The compound (3a) has crystallized in a triclinic P-1 space group with three independent molecules in the asymmetric unit, while the compound (3b) belongs to P21/c space group with one molecule in the asymmetric unit. The molecule (3b) differs from molecule (3a) by the presence of chlorine substituent. Additionally, the imidazo-thiadiazole entity is as usual planar. Intramolecular C-Hâ¯N hydrogen bonding between the imidazole and the phenyl ring of the molecule can be observed in (3a) & (3b). The molecules of (3a) are linked into two dimensional supramolecular hexagonal hydrogen bonded network sustained by C-Hâ¯F interaction, while those of (3b) are linked by bifurcated C-Hâ¯N interactions. Further, the molecular packing of both the compounds is stabilized by Ï-Ï stacking interactions between the benzene and imidazo-thiadiazole ring systems. © 2011 Elsevier B.V

Synthesis and Crystal Structure Analysis of 2-(Fluorobenzyl)-6-(4-Nitrophenyl) Imidazo[2,1-b][1,3,4]Thiadiazole

Preparation of 2-(4-fluorobexzyl)-6-(4-nitrophenyl)imidazo[2,1-b][1,3,4]thiadiazole is described and its crystal structure is discussed. The compound crystallizes in the monoclinic space group C2/c with a = 39.941(6) Å, b = 5.698(2) Å, c = 13.272(5) Å β = 90.880°, V = 3020(2) Å3, z = 8. The crystal structure is stabilized by weak intermolecular C-H…N,C-H…O,C-H…S, and C-H…F interactions