Mahmoud A. A. El-Remaily

Divinyl Sulfone Cross-Linked Cyclodextrin-Based Polymeric Materials: Synthesis and Applications as Sorbents and Encapsulating Agents

The aim of this study was to evaluate the crosslinking abilities of divinyl sulfone (DVS) for the preparation of novel water-insoluble cyclodextrin-based polymers (CDPs) capable of forming inclusion complexes with different guest molecules. Reaction of DVS with native α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and/or starch generates a variety of homo- and hetero-CDPs with different degrees of crosslinking as a function of the reactants’ stoichiometric ratio. The novel materials were characterized by powder X-ray diffraction, electron microscopy and for their sorption of phenol and 4-nitrophenol. They were further evaluated as sorbents with phenolic pollutants (bisphenol A and β-naphthol) and bioactive compounds (the hormone progesterone and curcumin). Data obtained from the inclusion experiments show that the degree of cross-linking has a minor influence on the yield of inclusion complex formation and highlight the important role of the CDs, supporting a sorption process based on the formation of inclusion complexes. In general, the inclusion processes are better described by a Freundlich isotherm although an important number of them can also be fitted to the Langmuir isotherm with R2 ≥ 0.9, suggesting a sorption onto a monolayer of homogeneous sites.

Bismuth triflate: A highly efficient catalyst for the synthesis of bio-active coumarin compounds via one-pot multi-component reaction

Abstract A series of coumarin-chalcone hybrid compounds and coumarins linked to pyrazoline was synthesized in good yield and short time using a simple and efficient method. This method involved the one-pot reaction of salicylaldehyde, an α-ketoester and an aromatic aldehyde (in the case of the coumarin-chalcone derivatives) in addition to hydrazine hydrate (in the case of the pyrazolyl coumarins) in the presence of a catalytic amount of bismuth triflate [Bi(OTf)3, 5 mol%]. The synthesized compounds showed scavenging activity towards the free radical 2,2-diphenyl-1-picrylhydrazyl. All compounds were characterized using IR, 1H NMR and 13C NMR spectroscopy.

Synthesis of Dihydroimidazole Derivatives under Solvent Free Condition andTheir Antibacterial Evaluation

Reaction of 2-guanidinobenzoxazole with several halogenated active methylene compounds has revealed formation of the corresponding dihydroimidazole derivatives under solvent free conditions in excellent yield. The anti-bacterial evaluation of the newly synthesized products against different types of Gram-positive and Gramnegative bacteria was performed. Most of products showed high inhibitory effect. The structure of all compounds has been characterized by on IR, 1H-NMR, 13C-NMR, Mass spectrum and some X-ray diffractions.

N-(4,6-Dimethyl-pyrimidin-2-yl)-1H-benzimidazol-2-amine.

There are two independent molecules in the asymmetric unit of the title compound, C13H13N5. In each molecule, an amino N atom is connected to a benzimidazole fused-ring system and a pyrimidine ring [these are aligned at 1.3 (1)° in one independent molecule and at 5.4 (1)° in the other]. The amino N atom of the fused ring forms an intramolecular N—H⋯O hydrogen bond to a pyrimidine N atom in each molecule. The amino N atom connecting the two ring systems interacts with the other N atom of the pyrimidine ring of an adjacent molecule, generating centrosymmetric hydrogen-bonded dimers.

2-(1,3-Benzothia-zol-2-yl)guanidinium chloride.

The non-H atoms of the cation of the title salt, C8H9N4S+·Cl−, are approximately co-planar (r.m.s. deviation = 0.037 Å), with one amino group forming an intramolecular hydrogen bond to the tertiary N atom of the benzothiazole fused-ring system. The cations and anions are linked by cyclic R 2 1(6) N—H⋯Cl hydrogen-bonding associations, generating helical chains running along the b-axis direction.

2-(1,3-Benzothia-zol-2-yl)guanidine.

In the title comound, C8H8N4S, one of the two independent molecules is essentially planar (r.m.s. deviation = 0.025 Å), while the other is slightly buckled (r.m.s. deviation = 0.131 Å) with the guanidine unit bent out of the plane of the fused-ring system by 16.8 (1)°. In the crystal, intermolecular N—H⋯N hydrogen bonds between the two independent molecules give rise to a hydrogen-bonded dimer. Addtional weak intermolecular N—H⋯N hydrogen bonds connect these dimers into chains along [010]. An intramolecular N—H⋯N hydrogen bond is also observed in each independent molecule.

Ethyl 4-anilino-2-methyl-5-oxo-1-phenyl-2,5-di­hydro-1H-pyrrole-2-carboxyl­ate

In the title compound, C20H20N2O3, the central 2,5-dihydro-1H-pyrrole ring [r.m.s. deviation = 0.014 (1) Å] is oriented at dihedral angles of 77.81 (6) and 25.33 (6)°, respectively, to the attached phenyl ring and the aniline phenyl ring. An intramolecular N—H⋯O hydrogen bond occurs. In the crystal, molecules are linked through pairs of N—H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(10) ring motif. Two weak C—H⋯π interactions are also observed.

Ethyl 4-(4-chloro­anilino)-1-(4-chloro­phen­yl)-2-methyl-5-oxo-2,5-di­hydro-1H-pyrrole-2-carboxyl­ate

In the title compound, C20H18Cl2N2O3, the dihedral angles between the central 2,5-dihydro-1H-pyrrole ring and the phenyl rings are 74.87 (9) and 29.09 (9)°. Intramolecular N—H⋯O and C—H⋯O hydrogen bonds occur. In the crystal, pairs of N—H⋯O hydrogen bonds link adjacent molecules into inversion dimers and form an R 1 2(6)R 2 2(10)R 1 2(6) ring motif through C—H⋯O hydrogen bonds.

2-Amino-4-phenyl-4H,10H-1,3,5-triazino[1,2-a]benzimidazol-3-ium chloride.

2-Guanidinobenzimidazole condenses with benzaldehyde in the presence of hydrochloric acid to form 2-amino-3,4-dihydro-4-phenyl-1,3,5-triazino[1,2-a]benzimidazole, which was isolated as its hydrochloride, C15H14N5 +·Cl−. The positive charge of the cation is formally placed on the double-bonded N atom of the dihydrotriazine ring. The six-membered dihydrotriazine that is fused with the benzimidazole ring system is relatively flat (r.m.s. deviation = 0.106 Å), with the methine C atom deviating most [0.164 (1) Å] from the mean-square plane. The phenyl ring connected to the methine C atom is disordered over two positions in a 0.558 (1):0.442 (1) ratio; the two orientations are aligned at 85.1 (1) and 89.6 (1)° with respect to the dihydrotriazine ring. In the crystal, adjacent cations and anions are linked by N—H⋯N and N—H⋯Cl hydrogen bonds, generating a double chain running along the b axis.

Epichlorohydrin cross-linked β-cyclodextrin: an environmental method for the synthesis of 2-arylbenzothiazoles derivatives in water

ABSTRACT In the present study, we report an environmentally benign synthesis of 2-arylbenzothiazoles derivatives from o-aminothiophenol and aldehydes in aqueous medium using β-cyclodextrin polymer as a catalyst and air as an oxidant. The polymer showed excellent catalytic activity, recovered, reused six times, and the catalyst efficiency remained unchanged. This suggests that the catalyst is an efficient and green catalyst for the synthesis of 2-arylbenzothiazoles derivatives and the obtained results could be promising for industrial synthesis of 2-arylbenzothiazoles derivatives. GRAPHICAL ABSTRACT