Synthesis, characterization and biological studies of sulfonamide Schiff's bases and some of their metal derivatives.

A new series of Schiff base ligands derived from sulfonamide and their metal(II) complexes [cobalt(II), copper(II), nickel(II) and zinc(II)] have been synthesized and characterized. The nature of bonding and structure of all the synthesized compounds has been explored by physical, analytical and spectral data of the ligands and their metal(II) complexes. The authors suggest that all the prepared complexes possess an octahedral geometry. The ligands and metal(II) complexes have been screened for their in vitro antibacterial activity against bacterial strains, Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi and for antifungal activity against fungal strains, Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. These assays enabled the identification of the metal complexes as an effective antimicrobial agent with low cytotoxicity.

Metal-based new sulfonamides: Design, synthesis, antibacterial, antifungal, and cytotoxic properties.

Cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes with 5-chlorosalicyladehyde derived Schiff base sulfonamides have been synthesized and characterized. Structure and bonding nature of all the synthesized compounds have been deduced from physical, analytical, and spectral (IR, (1)H NMR, (13)C NMR, Mass, electronic) data. An octahedral geometry has been proposed for all the metal complexes. The ligands and their metal complexes have been screened for their in vitro antibacterial, antifungal, and cytotoxic properties and results are reported.

Some new biologically active metal-based sulfonamide.

A new series of sulfonamide derived Schiff bases has been synthesized by a condensation reaction of various sulfonamides with aromatic aldehydes. The so obtained sulfonamide were further investigated for their chelation and biological properties with first row d-transition metal ions [cobalt(II), copper(II), nickel(II) and zinc(II)]. The nature of bonding and structure of all the synthesized compounds have been inferred from magnetic susceptibility and conductivity measurements, IR, (1)H and (13)C NMR, electronic spectral, mass spectrometry and CHN analysis data. The structure of ligand, 4-{[(E)-(5-bromo-2-hydroxy phenyl)methylidene]amino}-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide has also been determined by X-ray diffraction method. An octahedral geometry has been suggested for all the complexes. The ligands and their metal complexes have been screened for in vitro antibacterial, antifungal and cytotoxic properties. The result of these studies have revealed that all compounds showed moderate to significant antibacterial activity against one or more bacterial strains and good antifungal activity against various fungal strains.

Tris[bis-(2-methyl-prop-yl)dithio-phosphinato]bis-muth(III).

The title compound, [Bi(C(8)H(18)PS(2))(3)], contains a Bi(III) cation surrounded by three bis-(2-methyl-prop-yl)dithio-phosphinate anions, leading to a distorted octa-hedral coordination for the heavy metal. The Bi-S and S-P bond lengths are in the ranges 2.7694 (18)-2.8391 (17) and 2.019 (2)-2.035 (2) Å, respectively. The crystal structure is consolidated by C-H⋯S hydrogen bonds. Intra-molecular C-H⋯π inter-actions also play a role in stabilizing the mol-ecules.

4-[(E)-(5-Bromo-2-hydroxy-phen-yl)methyl-ideneamino]benzene-sulfonamide.

In the title compound, C(13)H(11)ClN(2)O(3)S, the dihedral angle between the benzene rings is 12.26 (33)° and an intra-molecular O-H⋯N hydrogen bond helps to establish the conformation. In the crystal, N-H⋯O and C-H⋯O inter-actions link the mol-ecules.

4-{2-[(5-Bromo-2-hydroxy-benzyl-idene)amino]eth-yl}benzene-sulfonamide.

In the title compound, C(15)H(15)BrN(2)O(3)S, the dihedral angle between the benzene rings is 6.1 (2)° and an intra-molecular O-H⋯N hydrogen bond helps to establish the conformation. In the crystal structure, the mol-ecules are linked by way of N-H⋯O and C-H⋯O hydrogen bonds.

Structural elucidation and biological significance of 2-hydroxy-1-naphthaldehyde derived sulfonamides and their first row d-transition metal chelates.

2-Hydroxy-1-naphthaldehyde derived sulfonamides and their first row d-transition metal chelates [cobalt (II), copper (II), nickel (II) and zinc (II)] have been synthesized and characterized. The nature of bonding and structure of all the compounds have been deduced from elemental analyses, infrared, 1H NMR, 13C NMR, mass spectrometry, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry has been suggested for all the complexes. The metal complexes were screened for their antibacterial and antifungal activities on different species of pathogenic bacteria and fungi and their biopotency has been discussed. The results of these studies revealed that all compounds showed moderate to significant antibacterial activity against all bacterial strains and good antifungal activity against various fungal strains. In-vitro cytotoxic properties of all the compounds against Artemia salina was also studies by brine shrimp bioassay.

4-Chloro-2-[(E)-({4-[N-(3,4-dimethyl-isoxazol-5-yl)sulfamo-yl]phen-yl}iminio)meth-yl]phenolate.

The title compound, C(18)H(16)ClN(3)O(4)S, is a Schiff base ligand in which the H atom of the hydr-oxy group has moved to the N atom of the imine group, resulting in a zwitterion. The structure is stabilized by an intra-molecular (N-H⋯O) and five inter-molecular (C-H⋯O, C-H⋯N and N-H⋯O) hydrogen bonds. The mol-ecules are linked to each other by hydrogen bonds and form a three-dimensional polymeric network. In addition, the aromatic rings are also involved in π-π inter-actions [centroid-centroid distance between aromatic rings = 3.7525 (11) Å].

4-(5-Chloro-2-hydroxy-benzyl-idene-amino)-N-(4,6-dimethyl-pyrimidin-2-yl)benzene-sulfonamide.

The title compound, C(19)H(17)ClN(4)O(3)S, is a Schiff base compound of 5-chloro-salicylaldehyde and sulfamethazine [4-amino-N-(4,6-dimethyl-2-pyrimidin-yl)benzene-sulfonamide]. The geometry around the S atom is distorted tetra-hedral, comprising two O atoms of the sulfonyl group, a C atom of a benzene ring and the amino N atom. The title compound has an intra-molecular O-H⋯N hydrogen bond and two inter-molecular C-H⋯O and N-H⋯O hydrogen bonds, which link neighbouring mol-ecules into 10-membered rings. As a result of an unavoidable conformational arrangement, a slightly short intra-molecular contact of distance 2.59 Šexists between an O atom of the sulfonyl group and an H atom of the sulfamethazine benzene ring.

4-Bromo-2-((E)-{4-[(3,4-dimethyl-isoxazol-5-yl)sulfamo-yl]phen-yl}iminio-meth-yl)phenolate.

The title compound, C(18)H(16)BrN(3)O(4)S, is a Schiff base ligand of 5-bromo-salicylaldehyde and sulfisoxazole [or N-(3,4-dimethyl-5-isoxazol)sulfanilamide]. The present structure is a zwitterion and is a more precise reinterpretation of the structure which was originally reported by Hämäläinen, Lehtinen & Turpeinen [Arch. Pharm. (1986), 319, 415-420]. The two aromatic rings which make π-π inter-actions [centroid-centroid distance 3.7538 (18) Å] through intermolecular interactions. There is also a C-Br⋯π inter-action [3.6333 (15) Å] with the heterocyclic ring. An intra-molecular N-H⋯O hydrogen bond also exists. Dimers are formed due to inter-molecular N-H⋯O hydrogen bonding. Inter-molecular C-H⋯O hydrogen bonding links a methyl C atom and the phenolate O atom. The dimers are linked by C-H⋯N hydrogen bonds, where the C atom is from the Schiff base group and the N atom is of five-membered heterocyclic ring.

4-{2-[(5-Chloro-2-hydroxy-benzyl-idene)amino]eth-yl}benzene-sulfonamide.

In the mol-ecule of the title compound, C(15)H(15)ClN(2)O(3)S, the S atom adopts a distorted tetra-hedral coordination geometry with two O atoms, one N atom of the amide group and one C atom of the aromatic ring. An intra-molecular O-H⋯N hydrogen bond results in the formation of a planar six-membered ring, which is oriented with respect to the adjacent aromatic ring at a dihedral angle of 3.38 (11)°. Thus, the two rings are nearly coplanar. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers.

4-[(E)-(5-Chloro-2-hydroxy-benzyl-idene)amino]benzene-sulfonamide.

In the mol-ecule of title compound, C(13)H(11)ClN(2)O(3)S, the aromatic rings are oriented at a dihedral angle of 12.27 (3)°. An intra-molecular O-H⋯N hydrogen bond results in the formation of a planar (mean deviation 0.0083 Å) six-membered ring, which is nearly coplanar with the adjacent ring at a dihedral angle of 2.36 (13)°. In the sulfonamide group, the S atom is 0.457 (3) Šfrom the plane through the O and N atoms. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules.

4-[(5-Bromo-2-hydroxy-benzyl-idene)amino]-N-(4,6-dimethyl-pyrimidin-2-yl)benzene-sulfonamide-4-bromo-2-[(E)-({4-[(4,6-dimethyl-pyrimidin-2-yl)sulfamo-yl]phen-yl}iminio)meth-yl]phenolate [0.61†(7)/0.39†(7)].

The title compound, 0.61C(19)H(17)BrN(4)O(3)S·0.39C(19)H(17)BrN(4)O(3)S, is a Schiff base derived from 5-bromo-salicylaldehyde and 4-amino-N-(4,6-dimethyl-2-pyrimidin-yl)benzene-sulfonamide(sulfamethazine) and is isostructural with its chloro analogue. The geometry of the title mol-ecule points to the enol (OH-C=C-C=N) form as the major tautomer, however two electron-density maxima corresponding to the H atoms of the OH and NH groups, found in the region of a strong intra-molecular N⋯H⋯O hydrogen bond, do not allow the elimination of the presence of the zwitterionic (O(-)-C=C-C=NH(+)) form in the crystal. Refinement of the occupancies of these H atoms gave a 0.61 (7):0.39 (7) ratio of the enolic and zwitterionic forms. The two benzene rings within the mol-ecule are nearly coplanar and the central benzene ring forms a dihedral angle of 84.1 (1)° with the pyrimidine fragment. An inter-molecular N-H⋯O hydrogen bond links mol-ecules into chains extended along the a axis and a C-H⋯O link is also present. The H atoms of one of the methyl groups are disordered over two sites with an occupancy ratio of 0.72 (7):0.28 (7).