Urmila H. Patel

Synthesis, spectroscopic characterization, antimicrobial activity and crystal structure of silver and copper complexes of sulfamethazine

Silver(I) and copper(II) complexes of 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzenesulfonamide (smz) have been synthesized and characterized by elemental analysis and infrared (IR), 1H NMR, and UV–vis spectroscopy. [Ag(smz)(pyridine)] (1) crystallizes in monoclinic system with space group P21/c and Z = 4, while [Cu(smz)2(pyridine)2]·H2O (2) crystallizes in triclinic system with space group P-1 and Z = 2. X-ray analysis revealed that silver in 1 is four-coordinate exhibiting distorted tetrahedral geometry, while copper in 2 is coordinated to six nitrogens leading to a highly distorted octahedral geometry. The molecular structures of both 1 and 2 are stabilized by N–H⋯O and C–H⋯π intermolecular and C–H⋯O intramolecular interactions. Water plays a significant role in crystal packing by forming strong N–H⋯Owater intramolecular as well as Owater–H⋯N intermolecular interactions in 2. The results of IR, UV–vis, 1H NMR spectral data and thermal analysis for 1 and 2 suggest that the binding of silver and copper to the sulfonamidic nitrogen is in agreement with the crystal structure determination. Antimicrobial activities of silver (1) and copper (2) complexes of sulfamethazine are studied by the dilution method against Staphylococcus aureus and Escherichia coli strains. Two new transition metal (Ag and Cu) complexes of sulfamethazine with different stoichiometries and coordination environments are synthesized, characterized, and tested as antimicrobial agents.

Pd doped SiO2 nanoparticles: an efficient recyclable catalyst for Suzuki, Heck and Sonogashira reactions

Palladium doped silica (Pd/SiO2) mesoporous material was synthesized via the sol–gel route using the P123 triblock copolymer as a structure directing agent. Pd/SiO2 was efficiently used as a catalyst for Suzuki, Heck and Sonogashira reactions under microwave irradiation. The catalyst exhibited high activity for all the coupling reactions and can be recycled nine times without a significant loss in its catalytic activity.

Crystal and molecular structure of sulfadimethoxine, polymorph III

Crystal structure of sulfadimethoxine, C 12 H 14 N 4 O 4 S, has been determined and refined to an R-value of 0.043 using direct methods. It crystallizes in the triclinic space group P1 with a = 7.946(1), b = 9.330(1), c = 10.407(1)A, α = 93.46(1), β = 95.43(1), y = 114.62(1)° and Z = 2. The dihedral angle between the two six - membered rings of the molecule is 77.6(8)°. Molecule adopts a gauche conformation about S8-N1 I bond with torsional angle of 60.0(2)°. The structure is mainly stable due to strong hydrogen bonds, amino nitrogen plays the role of donor in two different intermolecular hydrogen bonds where sulfonyl oxygen and pyrimidine nitrogen act as acceptor.

3-(2-Chloro-3-hy­droxy-4-meth­oxy­phen­yl)-1-(4,5-dimeth­oxy-2-methyl­phen­yl)prop-2-en-1-one

The title compound, C19H19ClO5, is a chloro derivative of a biologically significant chalcone family. The mean plane of the two substituted benzene rings are twisted by 55.33 (8)° with respect to each other. An intramolecular C—H⋯Cl hydrogen bond generates an S(5) graph-set motif. In the crystal, a bifurcated O—H⋯(O,O) hydrogen bond leads to an R 1 2(5) graph-set motif and to the formation of zigzag chains propagating along the c-axis direction. A weak π–π interaction involving the methylphenyl rings [centroid–centroid distance = 3.8185 (10) Å] and C—H⋯π interactions also occur.

A comparative study of novel chalcone derivative by X-ray and quantum chemical calculations (Ab-initio and DFT): Experimental and theoretical approach

ABSTRACT A novel bio-organic molecule, 3-(3-chloro-4-methoxy-phenyl)-1-(4,5-dimethoxy-2-methyl phenyl) prop-2-en-1-one (I), has been synthesized and characterized by FTIR, 1H, and 13C NMR. To understand the role of solvents, UV-vis absorption, and fluorescence study has been carried out using different solvents. The single-crystal X-ray diffraction technique has been studied to confirm the three dimensional structure of the compound and the hydrogen bond interactions involved in the stability of the structure. The ab-initio and density functional theory (DFT) are used to optimize the molecular structure. The calculated results show that the predicted geometry can well reproduce structural parameters. In addition, frontier molecular orbitals and Mullikan charge distributions are carried out by using RHF and B3LYP methods. The synthesized compound has been screened for its antimicrobial and antifungal activities against different panel of organisms.

Novel stereoselective 2,3-disubstituted quinazoline-4(3H)-one derivatives derived from glycine as a potent antimalarial lead

An optimization and modification of Grimmels method leading to cyclization and incorporation of glycine linked sulphonamide at position-2 in 4-quinazolin-(3H)-ones was accomplished. Generation of a lipophilic site at position-3 of 4-quinazolinones was explored by synthesis of imines, unfortunately leading to an isomeric mixture of stereoisomers. These stereoisomeric mixtures were further converted to a single isomer utilizing the novel methodology developed by the use of an aprotic solvent system. Moreover, a mixture of (Z)/(E)-isomers and single configuration was identified and ascertained using NMR, HMQC, HMBC and NOESY spectroscopic techniques. The synthesized entities were further screened for their antimalarial efficacy pertaining two active scaffolds 8m and 8s. The active molecules were sent forth for enzyme inhibitory study against presumed receptors h-DHFR and Pf-DHFR computationally as well as in vitro, proving their potency as dihydrofolate reductase inhibitors. The oral bioavailability of these active molecules was also predicted by the study of ADME properties, indicating good bioavailability of the active entities.

Hirshfeld surface analysis of sulfameter (polymorph III), sulfameter dioxane monosolvate and sulfameter tetrahydrofuran monosolvate, all at 296 K.

The ability of the antibacterial agent sulfameter (SMT) to form solvates is investigated. The X-ray crystal structures of sulfameter solvates have been determined to be conformational polymorphs. Both 1,4-dioxane and tetrahydrofuran form solvates with sulfameter in a 1:1 molar ratio. 4-Amino-N-(5-methoxypyrimidin-2-yl)benzenesulfonamide (polymorph III), C11H12N4O3S, (1), has two molecules of sulfameter in the asymmetric unit cell. 4-Amino-N-(5-methoxypyrimidin-2-yl)benzenesulfonamide 1,4-dioxane monosolvate, C11H12N4O3S·C4H8O2, (2), and 4-amino-N-(5-methoxypyrimidin-2-yl)benzenesulfonamide tetrahydrofuran monosolvate, C11H12N4O3S·C4H8O, (3), crystallize in the imide form. Hirshfeld surface analyses and fingerprint analyses were performed to study the nature of the interactions and their quantitative contributions towards the crystal packing. Finally, Hirshfeld surfaces, fingerprint plots and structural overlays were employed for a comparison of the two independent molecules in the asymmetric unit of (1), and also for a comparison of (2) and (3) in the monoclinic crystal system. A three-dimensional hydrogen-bonding network exists in all three structures, involving one of the sulfone O atoms and the aniline N atom. All three structures are stabilized by strong intermolecular N-H···N interactions. The tetrahydrofuran solvent molecule also takes part in forming significant intermolecular C-H···O interactions in the crystal structure of (3), contributing to the stability of the crystal packing.

1,3-Dimethyl-2-oxo-4,6-diphenyl-1,2,3,4-tetrahydropyridine-3-carbonitrile.

The crystal structure of the title compound, C(20)H(18)N(2)O, reveals a distorted half-chair conformation of the central tetrahydropyridine (THP) ring, with the cyano- and adjacent phenyl-substituted C atoms displaced by 0.329 (1) and -0.315 (1) A, respectively, from the THP best plane. Steric interactions force the phenyl rings out of the THP plane by 49.21 (9) and 65.76 (5). The cyano moiety is coplanar with the THP plane.

C—H...O hydrogen-bonding and C—H...π interactions in 3-(4-fluorophenyl)-1,5,7-trimethyl-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidine-2,4-dione

In the title compound, C(16)H(14)FN(3)O(2), a diverse set of weak intermolecular C--H...pi, pi-pi and C--H...O interactions link the molecules into sheets. The C--H...O interactions generate centrosymmetric rings with a graph-set motif of R(2)(2)(14) and chains with a C(8) motif.

C—H⋯N and C—H⋯π interactions in 2-ethoxy-4,6-diphenylpyridine-3-carbonitrile

The title compound, C(20)H(16)N(2)O, has two molecules in the asymmetric unit and the crystal structure shows that the central pyridine ring of each molecule has a flat boat conformation. The terminal C atom in one of the molecules is disordered over two positions, with relative occupancies of 0.594 (14) and 0.398 (14). Intermolecular C-H.N and C-H.pi interactions and pi-pi stacking, along with intramolecular C-H.N and C-H.pi interactions, help to stabilize the structure.