Yasemin Ünver

An experimental and DFT computational study on 4-(3-(1H-imidazol-1-yl)propyl)-5-methyl-2H-1,2,4-triazol-3(4H)-one monohydrate

The triazole compound 4-(3-(1H-imidazol-1-yl)propyl)-5-methyl-2H-1,2,4-triazol-3(4H)-one monohydrate has been synthesised and characterised by 1H-NMR, 13C-NMR, IR, and X-ray single-crystal determination. The compound crystallizes in the triclinic space group with a = 9.0366(7) Å, b = 11.5690(8) Å, c = 12.0571(9) Å, α = 110.733(6)°, β = 94.172(6)°, γ = 98.085(6)° and Z = 4. In addition to the molecular geometry from X-ray determination, the molecular geometry, vibrational frequencies and gauge, including atomic orbital (GIAO) 1H- and 13C-NMR chemical shift values of the title compound in the ground state, were calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The calculated results show that the optimised geometries can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. The energetic behaviour of the title compound in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager model. The total energy of the title compound decreases with increasing polarity of the solvent. The predicted nonlinear optical properties of the title compound are greater than those of urea. In addition, DFT calculations of the molecular electrostatic potentials, frontier molecular orbitals and thermodynamic properties of the title compound were carried out at the B3LYP/6-31G(d) level of theory.

New thiophene-1,2,4-triazole-5(3)-ones: highly bioactive thiosemicarbazides, structures of Schiff bases and triazole-thiols.

Key compound 2-(4-amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-tiazole-1-yl) acetohydrazide (3) was synthesized by reacting hydrazine hydrate with ethyl-2-(4-amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-tiazole-1yl)acetate (2), obtained in basic media from 4-amino-5-(thiophene-2-ylmethyl)-2H-1,2,4-triazole-3(4H)-one (1). Compound 3 was converted to thiosemicarbazide derivatives (4a-d) and Schiff base derivatives 6a-e and 7a-e. The treatment of compound 4 with NaOH gave 4-amino-2-((4-(4-aryl)-5-mercapto-4H-1,2,4-triazole-3-yl)methyl)-5-(thiophene-2-ylmethyl)-2H-1,2,4-triazole-3(4H)-ones (5a-d). All newly compounds, well characterized by elemental analyses, IR, (1)H NMR, (13)C NMR and mass spectral studies were tested for their antioxidant and antimicrobial activities. Thiosemicarbazide derivatives (4a-d) were highly active in two antioxidant tests with 69.0-88.2% DPPH· scavenging and 503-1257 μM TEAC values, while the others showed lower or no activity. The results of the two antioxidant tests correlated well. Moreover, Thiosemicarbazide derivatives (4a-d) also showed antibacterial activity against Staphylococcus aureus, Bacillus cereus, and Mycobacterium smegmatis. Thiosemicarbazide group deserves attention in the synthesis of bioactive compounds.

Synthesis of new 1,2,4-triazole compounds containing Schiff and Mannich bases (morpholine) with antioxidant and antimicrobial activities

Abstract Compound 2 was synthesized by reacting CS2/KOH with compound 1. The treatment of compound 2 with hydrazine hydrate produced compound 3. Then, compound 3 was converted to Schiff bases (4a–d) by the handling with several aromatic aldehydes. The treatment of triazole compounds 4a–d containing Schiff base with morpholine gave compounds 5a–d. All compounds were tested for their antioxidant and antimicrobial activities. The antioxidant test results of DPPH• radical scavenging and ferric reducing/antioxidant power methods showed good antioxidant activity. The triazole-thiol (3) was the most active, and the effect of the substituent type of the thiophene ring on the activity was same for both Schiff bases (4a–d) and Mannich bases (5a–d). Among the newly synthesized triazole derivatives, the Schiff base 4d and the Mannich base 5d carrying nitro substituent on the thiophene ring showed promising antibacterial and antifungal activity, with lower MIC values than the standard antibacterial ampicillin.

Ethyl 4-(3-ethyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-4-yl)benzoate

In the title compound, C13H15N3O3, the dihedral angle between the two aromatic ring is 51.06 (1)°. In the crystal, molecules are connected by pairs of N—H⋯O hydrogen bonds into centrosymmetric dimers.

2-Benzoylmethyl-4-[(2-benzylidene­ethylidene)amino]-5-(2-thienylmethyl)-2H-1,2,4-triazol-3(4H)-one

In the molecule of the title compound, C24H20N4O2S, the dihedral angle between the triazole and thiophene rings is 66.80 (4)° and the dihedral angle between the two benzene rings is 63.37 (4)°. An intramolecular C—H⋯O interaction results in the formation of a six-membered ring. A π⋯π contact between the benzene rings, [centroid–centroid distance = 3.918 (2) Å] may stabilize the structure. Weak C—H⋯π interactions are also present. The S, C and H atoms of the thiophene ring are disordered over two positions and were refined with occupancies of 0.654 (3) and 0.346 (3).

1-(Benzoyl­methyl)-4-(3,5-di­methyl-4H-1,2,4-triazol-4-yl)-3-(2-thienyl­methyl)-1H-1,2,4-triazol-5(4H)-one

In the title compound, C19H18N6O2S, none of the five- and six-membered rings are coplanar with the triazolone ring. Intramolecular C—H⋯N and intermolecular C—H⋯N and C—H⋯O hydrogen bonds, together with some C—H⋯π interactions, help to stabilize the structure.

2‐[2‐(Cyano­methoxy)­phenoxy]­aceto­nitrile

The title compound, C10H8N2O2, consisting of a benzene ring with two O—CH2—CN ortho substituents, has approximately C2 symmetry. The supramolecular structure of the compound is determined by two hydrogen bonds and two π–π stacking interactions.

Theoretical and antimicrobial activity study for Ethyl{4-[3-(1H-imidazole-1-yl)propyl]-3-methyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}acetate

ABSTRACT Ethyl{4-[3-(1H-imidazole-1-yl)propyl]-3-methyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}-acetate (I) was synthesized as described in the literature and studied by proton and carbon-13 nuclear magnetic resonance, Fourier transform infrared spectroscopic techniques. Theoretical calculations were performed by the density functional method with 6-311G(d,p) and 6-311++G(d,p) basis sets. Structural parameters of compound I, vibrational frequencies, and chemical shift values were determined. The antimicrobial activity of compound I was tested for seven standard bacteria; Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Yersinia enterocolitica, Listeria monocytogenes, Shigella flexneri, Pseudomonas aeruginosa, and one standard fungi isolate by microdilution broth assay with Alamar Blue Dye. The in vitro results show that compound I has antimicrobial activity against to two standard bacteria, Shigella flexneri and Listeria monocytogenes. And also, the antifungal activity was not detected against selected fungi isolate, Candida tropicalis.

4,4'-Butane-1,4-diylbis[3-ethyl-1H-1,2,4-triazol-5(4H)-one] and 4-hydroxy-3-n-propyl-1H-1,2,4-triazol-5(4H)-one

The title compounds, C12H20N6O2, (I), and C5H9N3O2, (II), display the characteristic features of 1,2,4-triazole derivatives. Compound (I) lies about an inversion centre which is at the mid-point of the central C-C bond. Compound (II) also contains a planar 1,2,4-triazole ring but differs from (I) in that it has a hydroxy group attached to the ring. Molecules of (I) are held together in the crystal structure by intermolecular N-H...O contacts and by weak pi-pi stacking interactions between the 1,2,4-triazole moieties. Compound (II) contains intermolecular O-H...O and N-H...O hydrogen bonds.

Crystal Structure of 4-Amino-3-(thiophen-2-ylmethyl)-1H-1,2,4-triazole-5(4H)one Monohydrate

The molecular structure of the 4-amino-3-(thiophen-2-ylmethyl)-1H-1,2,4-triazole-5(4H)one monohydrate was determined by X-ray diffraction. The compound crystallizes in the monoclinic sp. gr. C2/c with Z = 4 in the unit cell. The title compound is not planar. The dihedral angle between the thiophene and 1,2,4-triazole rings is 73.4(5)°. In the crystal structure, the molecules are connected by intermolecular N–H···O, N–H···N, O–H···O, and C–H···N type hydrogen bonds. The N–H···N and C–H···N hydrogen bonds link the molecules into infinite chains along the c axis.