Bilge Eren

FT-IR, dispersive Raman, NMR, DFT and antimicrobial activity studies on 2-(Thiophen-2-yl)-1H-benzo(d)imidazole

2-(Thiophen-2-yl)-1H-benzo[d]imidazole (TBI) was synthesized under microwave conditions and was characterized by FT-IR, dispersive Raman, (1)H-, (13)C-, DEPT-, HETCOR-NMR spectroscopies and density functional theory (DFT) computations. The FT-IR and dispersive Raman spectra of TBI were recorded in the regions 4000-400 cm(-1) and 4000-100 cm(-1). The experimental vibrational spectra were interpreted with the help of normal coordinate analysis based on DFT/B3LYP/6-311++G(d,p) theory level for the more stable tautomeric form (Tautomer 1). The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. A satisfactory consistency between the experimental and theoretical findings was obtained. The frontier molecular orbitals (FMOs), atomic charges and NMR shifts of the two stable tautomeric forms were also obtained at the same theory level without any symmetry restrictions. In addition, the title compound was screened for its antimicrobial activity and was found to be exhibit antifungal and antibacterial effects.

Molecular structure and spectroscopic analysis of 1,4-Bis(1-methyl-2-benzimidazolyl)benzene; XRD, FT-IR, dispersive-Raman, NMR and DFT studies.

This study reports the structural characterization of a bis-benzimidazole derivative, 1,4-Bis(1-methyl-2-benzimidazolyl)benzene (BMBB), by using spectroscopic and quantum chemical methods. The BMBB molecule was synthesized under microwave conditions and was characterized by using single-crystal X-ray diffraction, FT-IR, dispersive Raman and NMR spectroscopies. The potential energy surface scan study was carried out for the conformation of the theoretical structure. Quantum chemical calculations of relative energies, molecular geometry, vibrational wavenumbers, frontier molecular orbitals, atomic charges and gauge including atomic orbital (GIAO) (1)H and (13)C-NMR chemical shifts of the compound were carried out by using density functional method (DFT) at B3LYP/6-311++G(d,p) theory level. The complete assignments of the vibrational modes were performed with DFT calculations combined with scaled quantum mechanics force field (SQMFF) methodology. A satisfactory consistency between the experimental and theoretical findings was obtained. On account of the relative energies, population analysis and XRD results, the most stable conformational form of the molecule was also determined.

Surface Acidity of H-Birnessite: Infrared Spectroscopic Study of Formic Acid Decomposition

ABSTRACT This paper presents the adsorption and thermal decomposition mechanism of formic acid on an H-birnessite sample. Changes in the surface and structure were characterized using infrared spectroscopy, N2 gas adsorption–desorption, and thermal analysis techniques. The acid sites of H-birnessite were investigated by infrared and thermal analysis using pyridine as a molecular probe. Decomposition of formic acid started on H-birnessite at 120°C and was complete at 400°C. Infrared spectra revealed that the molecularly adsorbed formic acid species were transformed to a formate species, and the formate species were transformed to CO. The most stable adsorption structure for formic acid was found as a molecular monodentate configuration.

Copper doped K-birnessite as an efficient catalyst for the synthesis of 2-aryl benzimidazoles

In this study, an efficient and highly selective synthesis of 2-aryl benzimidazoles from the reaction of o-phenylenediamine and aromatic aldehydes in the presence of birnessite type copper doped manganese oxide (BCM) is reported. BCM was synthesized by the one-step hydrothermal method. Recycling of BCM up to five runs was investigated with appreciable yield and selectivity of the products. The best overall yields and selectivities were obtained in methanol. The crystal structure and thermal stability of BCM are characterized by using XRD, IR and thermal analysis techniques. The acid sites of BCM were investigated by IR using pyridine as a molecular probe. The improved catalytic activity observed in the BCM catalyst was associated to a high lattice oxygen mobility and availability due to the formation of Cu–O–Mn bridges.

SIMPLE, MILD, AND HIGHLY EFFICIENT SYNTHESIS OF 2-SUBSTITUTED BENZIMIDAZOLES AND BIS- BENZIMIDAZOLES

A new convenient method for preparation of 2-substituted benzimidazoles and bis-benzimidazoles is presented. In this method, o-phenylenediamines were condensed with bisulfite adducts of various aldehydes and di-aldehydes under neat conditions by microwave heating. The results were also compared with results of synthesis by conventional heating under reflux. Structures of the products were confirmed by infrared, 1H- and 13C-NMR spectroscopy. Short reaction times, good yields, easy purification of products, and mild reaction conditions are the main advantages of this method.

Catalysis and reaction mechanisms of N-formylation of amines using Fe(III)-exchanged sepiolite

This study presents a rapid, economical and “green” N-formylation of anilines with formic acid (FA) using Fe(III)-exchanged sepiolite (IES) as a catalyst. The IES exhibited excellent catalytic properties and the reactions were complete within 20.90 min to afford products with high yields. The adsorption mechanism of FA on the IES sample was studied by infrared (IR) spectroscopy at a temperature range of 120–400°C. The thermal desorption of pyridine was detected by the IR technique to estimate the acidity of IES. Lewis acid-bound pyridine bands at 1618–1631 cm-1 and 1443–1445 cm-1 were observed even after the IES sample was heated above 400°C.

4-Methyl-N-(4-methyl­phenyl­sulfon­yl)-N-phenyl­benzene­sulfonamide

The whole molecule of the title compound, C20H19NO4S2, is generated by twofold rotational symmetry. The N atom is located on the twofold rotation axis and has a trigonal-planar geometry. It is bonded by two S atoms of two symmetry-related 4-methylphenylsulfonyl groups and by the C atom of the phenyl ring, which is bisected by the twofold rotation axis. The benzene and phenyl rings are oriented at a dihedral angle of 51.48 (5)° while the pendant benzene rings are inclined to one another by 87.76 (9)°. In the crystal, weak C—H⋯O hydrogen bonds link the molecules, forming a three-dimensional network.

The Synthesis and Acid-Catalyzed Hydrolysis of N-(4-Substitutedphenyl)-O-Benzenedisulfonimides

Abstract The acid catalyzed hydrolyses of some cyclic disulfonimides, N-(4-substitutedphenyl)-o-benzenedisulfonimides (1a–d) have been studied in concentrated aqueous acidic solutions. Analysis of the data by the Excess Acidity Method, activation parameters, substituent, and solvent deuterium isotope effect are all indicate hydrolysis by an A-1 mechanism in the studied range. GRAPHICAL ABSTRACT