Mahmoud Al-Refai

Interconversion of copper(II) to copper(I): synthesis, characterization of copper(II) and copper(I) 2,2′-biquinoline complexes and their microbiological activity

The complexes [Cu(biq)2]Cl2 and [Cu(biq)2]BF4·biq (biq = 2,2′-biquinoline) have been prepared and characterized. The interconversion to copper(I) complex [Cu(biq)2]BF4·biq, from [Cu(biq)2]Cl2 has been established. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV-vis and 1H- and 13C-NMR spectroscopy. The X-ray analysis of the complex [Cu(biq)2]BF4·biq supports the assumption of the interconversion of copper(II) to copper(I) in this case. The crystal structure shows that geometry around the metal is severely distorted from Td, and displays many supramolecular motifs incorporating both hydrophobic (aryl···aryl) and hydrophilic (C–H···F) intermolecular interactions. The microbiological activity of the complexes against bacteria and fungi was found to be high against Candida albicans, and slight to moderate against bacteria. The antimicrobial activity of [Cu(biq)2]BF4·biq was slightly better than that observed for [Cu(biq)2]Cl2 against both bacteria and fungi.

Synthesis and characterization of metal 2-pyridine carboxaldehyde-N-methyl-N-2-pyridyl hydrazone complexes and their microbiological activity

Complexes of Cu(II), Mn(II), Co(II), Ni(II), Hg(II), Cd(II) and Rh(III) with 2-pyridine carboxaldehyde-N-methyl-N-2-pyridylhydrazone ( pamph) have been prepared and characterized. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV–vis and 1H NMR spectroscopic methods. The microbiological activity of the complexes was investigated against bacteria and fungi. Most of the complexes studied appear to be active against bacteria while all are active against fungi. The Cu, Cd and Hg complexes exhibit the highest activity against both bacteria and fungi.

Synthesis of 2,2′-bipyrimidine platinum(II) complexes

Multinuclear Pt(II) complexes of 2,2′-bipyrimidine (bipm) were prepared and characterized by elemental analyses and standard spectroscopic techniques. The complexes were formulated as [Pt(bipm)2][PtCl4]PhCN (1), [Pt3(μ-bipm)2(bipm)2]Cl6 (2), [Pt2(μ-bipm)(bpy)Cl2]Cl2 (3), [Pt3(μ-bipm)2(biq)2]Cl6·Me2CO·MeCN (4), [Pt3(μ-bipm)2(dmg)2]Cl2·MeCN (5) and [Pt5(μ-bipm)2(dmg)2]Cl8·2PhCN (6), [Pt3(μ-bipm)2(bpy)2]Cl6·2Me2CO·6PhCN (7), [Pt4(μ-bipm)3(phen)2]Cl8·8PhCN (8), [Pt4(μ-bipm)3(ox)2]Cl4·H2O·2PhCN (9); (bpy = 2,2′-bipyridine; dmg = dimethylglyoxime; ox = oxalate; phen = 1,10-phenanthroline; biq = 2,2′-biquinoline).

Synthesis, Spectral Characterization and Fluorescent Assessment of 1,3,5-Triaryl-2-pyrazoline Derivatives: Experimental and Theoretical Studies

Two new pyrazoline derivatives, namely 5-(4-bromophenyl)-3-(5-chlorothiophen-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (3) and 5-(4-bromophenyl)-3-(2,5-dichlorothiophen-3-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (4) have been synthesized and characterized based on their spectral (IR, 1H and 13C NMR and MS) data and microanalysis. The fluorescence properties of 3 and 4 were studied by UV–Vis and emission spectroscopy. For compound 3, a fluorescence emission was observed in the blue region of the visible spectrum. The effect of different solvents on fluorescence was also investigated. Density Functional Theory calculations have also been performed to gain insight into geometric, electronic and spectroscopic properties of the pyrazoline derivatives. Both structures are analysed and compared in order to rationalize the different behaviour in 3 and 4.

Synthesis of Fluorescent 1-(3-Amino-4-(4-(tert-butyl)phenyl)−6-(p-tolyl)furo[2,3-b]pyridin-2-yl)ethan-1-one: Crystal Structure, Fluorescence Behavior, Antimicrobial and Antioxidant Studies

Furopyridine III, namely 1-(3-amino-4-(4-(tert-butyl)phenyl)-6-(p-tolyl)furo[2,3-b]pyridin-2-yl)ethan-1-one, synthesized from 4-(4-(tert-butyl)phenyl)-2-oxo-6-(p-tolyl)-1,2-dihydropyridine-3-carbonitrile I in two steps. The title compound is characterized by NMR, MS and its X-ray structure. The molecular structure consists of planar furopyridine ring with both phenyl rings being inclined from the furopyridine scaffold to a significant different extent. There are three intramolecular hydrogen bonds within the structure. The lattice is stabilized by N—H…O, H2C—H …π and π…π intermolecular interactions leading to three-dimensional network. Compound III exhibits fluorescent properties, which are investigated. Antimicrobial potential and antioxidant activity screening studies for the title compound III and the heterocyclic derivatives, I and II, show no activity towards neither bacterial nor fungal strains, while they exhibited weak to moderate antioxidant activity compared to reference.

Synthesis, characterization and antimicrobial activity of new chalcones and their 6-aryl-4-(2,5-dichlorothiophen-3-yl)-6H-1,3-thiazin-2-amine derivatives

GRAPHICAL ABSTRACT ABSTRACT Chalcones (5a-h) were prepared in high yields via the condensation of 3-acetyl-2,5-dichlorothiophene (3) with aryl aldehydes (4a-h). The reaction of the resulting chalcones with thiourea in the presence of a catalytic amount of hydrochloric acid provided the 1,3-thiazin-2-amine derivatives (6a-g) in moderate yields. All new compounds were characterized by extensive NMR analysis data, including 1D NMR experiments (1H and 13C) and 2D NMR experiments (COSY, HMBC, HSQC), as well as ESIMS and HRESIMS data. The newly synthesized compounds were evaluated for their biological activities, which demonstrate a very good to low bioactivities as antibacterial and antifungal, respectively.

The Reaction of Cyanamidium Salts with Ylidenecyanamide Derivatives

Cyanamidium salts 1undergo ene reactions with ylidenecyanamide derivatives 5to afford conjugated iminium salts 12. The N,N,Nʹ-trialkylcyanamidium salts 1react as the ene, and the ylidenecyanamide derivatives 5react as the enophile components to form the 2-azoniaallene salts 11 followed by the formation of conjugated iminium salts 12 as cationic polynitrogen compounds with guanidine and amidine subgroups. The constitution of the new conjugated iminium salts 12 was secured by elemental analyses and spectroscopic data (IR and NMR). Graphical Abstract The Reaction of Cyanamidium Salts with Ylidenecyanamide Derivatives

Synthesis, Spectroscopic Characterization and X-ray Structure Analysis of 6-(2,5-Dichlorothiophen-3-yl)-3,4-dihydro-4-(4-methoxyphenyl)pyrimidine-2(1H)-thione

The title compound was prepared by the condensation of (E)-1-(2,5-dichlorothiophen-3-yl)-3-(4-methoxy)prop-2-en-1-one and thiourea in the presence of KOH. In the title compound, C34H28Cl16N4O2S4, the asymmetric unit consists of two independent molecules and four independent chloroform molecules. The heterocyclic pyrimidine-2(1H)-thione rings adopt a flattened boat conformation. The methoxyphenyl rings are perpendicular to the pyrimidine-2(1H)-thione rings with dihedral angles of 81.20 and 79.85° in both independent molecules. The dichlorothiophene rings are twisted compared to the pyrimidine-2(1H)-thione rings with dihedral angles of 40.59 and 39.36° in the independent molecules. The methoxyphenyl group has an axial orientation. Intermolecular C–H···S, C–H···O, C–H··· π vertex-to-face intermolecular interactions between chloroform C–H groups and the center of the phenyl rings and extensive Cl···Cl intermolecular interactions are found in the crystal structure. All interactions consolidate a three dimensional network. The molecular structure was further analyzed using spectroscopic methods. Mass ESI-HMRS measurements were performed. The HRESIMS analysis revealed the molecular formula, C15H12Cl2N2OS2, with [M+H]+ and [M+H+2]+ and [M+H+4]+ isotopic clusters characteristic for a dichlorinated compound. The compound was also thoroughly characterized by 1H, 13C, NMR spectra and 2D NMR spectra (COSY, HSQC and HMBC).Graphical AbstractSynthesis, characterization, molecular, crystal structure and crystal supramolecularity of the three dimensional network structure of 6-(2,5-dichlorothiophen-3-yl)-3,4-dihydro-4-(4-methoxyphenyl)pyrimidine-2(1H)-thione are reported.

One-Pot Synthesis of 2-Alkyl/arylamino-6-chlorothieno(3,2-e)-1,3- thiazin-4-one

Alkyl/arylamino-6-chlorothieno(3,2-e)-1,3-thiazin-3-one derivatives were prepared in one-pot synthesis by refluxing alky/arylisothiocyanates and 2,5-dichloro-3-thiophene- carboxamide. Alternatively, these derivatives were prepared by the intramolecular cyclization of the deprotonated 2,5-dichloro-N-(alkyl/arylaminocarbonothioyl)thiophene-3-carboxamides, which were obtained by the reaction of the deprotonated 2,5-dichloro-3-thiophene-carboxamide with alky/arylisothiocyanates. The structures of the newly synthesized bicyclic derivatives, and their acyclic precursors, were confirmed based on microanalytical and spectral (IR, MS, and NMR)

3-Bromo-N-(3,5-di-tert-butyl­phen­yl)propanamide

The title compound, C17H26BrNO, exhibits a small twist between the amide residue and the benzene ring [C—N—C—C torsion angle = 29.4 (5)°]. In the crystal, the amido NH group is involved in N—H⋯O hydrogen bonding, which connects molecules into chains parallel to the c axis.