P. Thomas Muthiah

Supramolecular organisation via hydrogen bonding in trimethoprim sulfonate salts

The present study deals with the crystal structures of four organic salts, namely, trimethoprim benzene sulfonate monohydrate 1, trimethoprim sulfanilate monohydrate 2, trimethoprim p-toluene sulfonate 3 and trimethoprim 3-carboxy-4-hydroxybenzene sulfonate dihydrate 4. Trimethoprim (TMP) is protonated at one of the ring nitrogens of the pyrimidine ring. Generally, in the TMP carboxylate complexes, the protonated pyrimidine ring is hydrogen-bonded to the carboxylate group forming a cyclic fork-like hydrogen-bonded bimolecular motif. In structures 1–3, the sulfonate group plays the role of the carboxylate anion. In compounds 1 and 2, there is no pairing of the pyrimidine rings because the pairing sites are blocked by water molecules donating hydrogen to the unprotonated ring nitrogen. Two of the cyclic motifs are bridged by the water molecule donating two hydrogen atoms, leading to a hydrogen-bonded supramolecular chain. This chain pairs with another chain running in the opposite direction. These two chains are cross-linked by O–H⋯O hydrogen bonds. In compound 2, two of the hydrogen atoms of the amino group of the sulfanilate bridge two methoxy oxygen of the two TMP cations via N–H⋯O hydrogen bonds resulting in a supramolecular zig-zag chain. In compound 3, two inversion related cyclic motifs are paired through a pair of N–H⋯N hydrogen bonds involving the 4-amino group and the N3 atom of the pyrimidine ring. In addition to the pairing, one of the sulfonate oxygen atoms bridges the 2-amino and 4-amino groups on either side of the paired bases, resulting in a self-complementary DADA (D represents the hydrogen bond donor and A represents hydrogen bond acceptor) array of quadruple hydrogen bonding patterns. In compound 4, one of the water molecules forms a hydrogen-bonded dimer with the inversion-related water molecule. The 3-carboxy-4-hydroxybenzene sulfonate moiety self-assembles into a supramolecular chain along the c axis through O–H⋯O hydrogen bonds. Two such oppositely running supramolecular chains are connected by dimeric and monomeric water molecules. The variation of supramolecular organization via hydrogen bonding in the four different trimethoprim sulfonate salts has been discussed.

Metal-drug interactions: synthesis and crystal structure of dichlorodithiabendazolecobalt(II) monohydrate

Abstract The crystal structure of dichlorodithiabendazolecobalt(II) monohydrate [CoCl2(C10H7N3S)2·H2O] has been determined from X-ray diffraction data using Mo Kα radiation. The crystals are monoclinic, P2 1 /c with a = 15.328(5), b = 11.2131(8), c = 13.967(5) A , β = 114.27(1)° and Z = 4 . The structure was solved and refined to a final R value of 0.0332 with 3717 observed reflections. Two chlorine atoms and two thiabendazole ligands form an octahedral geometry around cobalt. Each thiabendazole, [2-(4-thiazolyl)-1H-benzimidazole], is bidendate chelating and is bonded to cobalt through the nitrogen atoms of the thiazolyl and benzimidazole rings in cis configuration. The protonated nitrogen atom of the imidazole ring is trans to the thiazole nitrogen atom.

Interplay of coordination and hydrogen bonding modes in the self-assembly of the supramolecular network in copper(II) phthalate–trimethoprim complex (0.5:1:1)

Abstract Trimethoprim cations forming self complementary hydrogen-bonded DADA arrays interact with the copper–phthalate supramolecular frameworks through extensive hydrogen bonding.

Metal-pyrimidine interaction: synthesis and crystal structure of a cadmium complex of trimethoprim ([CdBr2(TMP)2(H2O)2]·H2O, TMP = trimethoprim)

The crystal structure of a cadmium complex of trimethoprim ([CdBr2(TMP)2(H2O)2] · H2O, TMP = trimethoprim) has been determined from X-ray diffraction data using MoKα radiation. The crystals are monoclinic, C2/c, with a = 7.7811(11), b = 15.439(3) c = 29.645(6)Å, β = 97.23(2)° and Z = 4. Trimethoprim (2,3-diamino(3′,4′,5′trimethoxybenzyl)pyrimidine) acts as a monodentate ligand. Cadmium is coordinated to N(1) atoms of two trimethoprim moieties. The octahetral coordination geometry around cadmium is completed by two Br-ions and two water molecules. The complex has a two-fold axis coinciding with a crystallographic two-fold axis. There is an interligand hydrogen bond between the bromide ion and the 2-amino group of the pyrimidine.

1, 5-Bis (2-hydroxyacetophenone)thiocarbohydrazone: A novel colorimetric and fluorescent dual-mode chemosensor for the recognition of fluoride

1,5-Bis (2-hydroxyacetophenone)thiocarbohydrazone (H4L) has been synthesized and characterized by means of spectroscopic and single crystal X-ray diffraction methods. Interactions of the H4L with a variety of anions were investigated using a combination of UV-visible and fluorescence spectroscopic methods in a biological competing solvent DMSO. The H4L has a high degree of selectivity for fluoride over other anions. (1)H NMR titration experiments indicate that a deprotonation process is involved in the chemo sensing process.

Synthesis, crystal structure and theoretical studies of a Schiff base 2-[4-hydroxy benzylidene]-amino naphthalene.

The molecular structure of a new Schiff base, 2-[4-hydroxy benzylidene]-amino naphthalene (HBAN) has been examined by HF and B3LYP/6-311++G(d,p) calculations. The X-ray structure was determined in order to establish the conformation of the molecule. The compound, C17H13NO, crystallizes in the orthorhombic, P212121 space group with the cell dimension, a=6.2867(2), b=10.2108(3), c=19.2950(6) Å, α=β=γ=90° and z=4. The asymmetric unit contains a molecule of a Schiff base. A strong intermolecular O-H⋯N and a weak C-H⋯O hydrogen bonds stabilized the crystal structure. The vibrational spectra of HBAN have been calculated using density functional theoretical computation and compared with the experimental. The study is extended to the HOMO-LUMO analysis to calculate the energy gap (Δ), Ionization potential (I), Electron Affinity (A), Global Hardness (η), Chemical Potential (μ) and Global Electrophilicity (w). The calculated HOMO and LUMO energy reveals that the charge transfer occurs within the molecule.

Synthesis and crystal structure of lithium 8-hydroxyquinoline-5-sulfonate tetrahydrate

A lithium salt of 8-hydroxyquinoline-5-sulfonic acid, Li2(C9H5NO4S)·4H2O, has been synthesized and characterized by X-ray diffraction techniques. The salt is monoclinic, space group P21/c, with a = 10.323(3), b = 10.088(9), c = 11.792(6) Å and β = 92.21(3)°. Li ions adopt two different distorted tetrahedral geometries. Li(1) is surrounded by a water molecule, N,O atoms of the oxine ring and one of the oxygen atoms of the sulphonate group. Li(2) is surrounded by three water molecules and an oxygen atom of the sulphonate group. The two lithium ions are bridged by a water molecule, leading to a polymeric network.

8-Hydroxyquinolinium-salicylate-salicylic acid (1/1/1) complex, C9H8NO+.C7H5O3-C7H6O3

An intramolecular N1-H...O hydrogen bond is present in the 8-hydroxyquinolinium cation. An intramolecular hydrogen bond is present in each of the salicyl moieties (between the phenolic OH and the carboxy group). The crystal structure is stabilized by a network of intermolecular N-H...O, O-H...O and C-H...O hydrogen bonds.

Molecular structure of N,N-bis(benzimidazol-2-ylethyl)sulfide dihydrochloride dihydrate, a heavy metal chelating ligand

The title compound contains two benzimidazole nitrogens and one thioether sulfur atom, which are potential sites for metal ion binding. Both the benzimidazole nitrogens of the molecule are protonated. The benzimidazole rings are almost parallel to each other, the dihedral angle being 6.9(1)°. The C−S−C bond angle is 100.6(2)° and the C−S−C−C torsion angles are −75.9(3)° and −80.6(3)°, leading to gauche conformation which is one of the favored conformations in the crystalline state of simple monothioethers.

Supra­molecular hydrogen-bonding patterns in the N(9)—H protonated and N(7)—H tautomeric form of an N6-benzoyl­adenine salt: N6-benzoyl­adeninium nitrate

The N9—H protonated and N7—H tautomeric form of N 6-benzoyladenine cations are bridged by one of the oxygen atoms of the nitrate anion via N—H⋯O hydrogen bonds, generating a ribbon motif. The cations also form base pairs via N—H⋯O and C—H⋯N hydrogen bonds.