In vitro study of the interaction of cysteine with a thiazide diuretic (hydrochlorothiazide) at different ph by voltammetric and spectroscopic techniques

The interaction of cysteine (RSH) with a thiazide diuretic, hydrochlorothiazide (HCTZ) was characterized by UV-Vis absorption spectroscopy and square-wave voltammetry in Britton-Robinson (B-R) buffer solution (with pH 5, 7 and 9). On the square-wave voltamogram of cysteine, the reduction peak current of mercurous cysteine thiolate (Hg₂(RS)₂) decreased and its peak potential shifted to more positive values with the addition of HCTZ. This results showed that the RSH interacted with HCTZ. The stoichiometry of HCTZ-RSH molecular complex was determined by voltammetric data with the result of 1: 1. By using linear regression analysis of the voltammetric data at pH 5, 7 and 9, the apparent formation constants of HCTZ-RSH complex were calculated to be 9.54 × 10³, 2.80 × 10⁴ and 2.55 × 10⁴ M^?1, respectively. At the same time, this interaction was also supported by UV-Vis spectroscopic measurements. According to the voltammetric and spectroscopic results, it was suggested that the interaction mode between RSH and HCTZ molecules might be a combination of hydrophobic interactions and hydrogen bonds.     

Synthesis,characterization and crystal structures of new Zinc(II) and Nickel(II) complexes containing morpholine moiety and their antibacterial studies

The ligand 1,2-dimorpholinoethane (DME) was used to prepare Zn(II) and Ni(II) complexes of the general formulation MLX₂ (L = DME, X = Cl or NO₃). Zinc(II) complex exhibits spectral properties indicative of a distorted tetrahedral geometry, with DME coordinating through two nitrogen atoms and two chlorides completing the tetrahedron. This is in contrast to the six-coordinated, distorted octahedral geometry exhibited by nickel(II) complex of DME when NO₃ was used as counter ions. The X-ray diffraction confirms the structures of two complexes and shows that the ligand coordinates through two nitrogen atoms while the two ether linkages are not involved in complexation, which would have been the case if the morpholine rings were in the boat form. The ligand and related complexes have antibacterial activity against the five Gram-positive bacteria: Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Streptococcus pyogenes and also against the three Gram-negative bacteria: Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442 and Klebsiella pneumonia ATCC 70063. The results showed that in some cases the antibacterial activity of the complexes exceeded the one of sulfisoxazole used as a standard.     

Analysis of fluorescence quenching of pyronin B and pyronin Y by molecular oxygen in aqueous solution

The fluorescence quenching of pyronin B and pyronin Y molecules by molecular oxygen in aqueous solution was studied by using steady-state and time-resolved fluorescence and UV-Vis absorption spectroscopy techniques. In order to understand the quenching mechanism, fluorescence decays, absorption and fluorescence spectra of the probes were recorded as a function of the oxygen concentration and temperature. The quenching was found to be appreciable and shows positive deviation in the Stern-Volmer representation obtained from the fluorescence intensity ratio. Fluorescence quenching constants (k_q) were calculated from the τ_o/τ vs. [Q] plots having linear correlation and compared with calculated diffusion-controlled rate constants (k_diff) values. Experimental results were in good agreement with the simultaneous dynamic and static quenching model.     

Potentiometric Studies on Complexation of Cu(II) Ion with Methyl/Nitro-Substituted 1,10-Phenanthrolines and Selected Amino Acids

Protonation constants of methyl/nitro substituted 1,10-phenanthrolines {(m/n-sphen): 4-methyl-phenanthroline (4-mphen), 5-methyl-1,10-phenanthroline (5-mphen), 4,7-dimethyl-1,10-phenanthroline (dmphen), 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) and 5-nitro-1,10-phenanthroline (5-nphen)] and the amino acids (aa) l-tyrosine (tyr) and glycine (gly), and their corresponding binary and ternary stability constants with Cu(II), were determined in aqueous 0.1 mol·L^?1 KCl ionic media at 298.15 K. The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the “BEST” software package. The species distribution diagrams were obtained using the “SPE” software package under the experimental conditions described. The order of stability of the ternary complexes in terms of the primary ligands is [Cu(tmphen)(aa)]⁺ > [Cu(dmphen)(aa)]⁺ > [Cu(4-mphen)(aa)]⁺ > [Cu(5-mphen)(aa)]⁺ > [Cu(5-nphen)(aa)]⁺. The stability constants of the ternary complexes decrease in the following order: [Cu(m/n-sphen)(gly)]⁺ > [Cu(m/n-sphen)(tyr)]⁺, which is identical to the sequence found for the binary complexes of Cu(II) with gly and tyr.     

含黄酮的三价铁配合物合成及其药理性质(英文)

3,3,4,7-四羟基黄酮与1,3-二环己基碳二亚胺在4-二甲胺吡啶存在下反应,得到2,2-双(3,3,4,7-四羟基黄酮)1,3-二环己基碳二亚胺。三价金属离子与上述合成得到的配体螯合,对此四面体结构的双核Fe(Ⅲ)配合物的血液学及病理学数据进行了讨论,同时研究了合成的配体作为螯合剂清除鼠肝胰组织中超载的铁的能力。结果表明作为口服药其作为双齿配体的螯合能力与市售用于治疗地中海贫血的药物"去铁敏"相近。     

Hydrogen‐bond motifs in N‐monosubstituted derivatives of barbituric acid: 5‐allyl‐5‐isopropyl‐1‐methylbarbituric acid (enallylpropymal) and 1,5‐di(but‐2‐enyl)‐5‐ethylbarbituric acid

Both title structures exhibit essentially planar barbiturate rings. The crystal structure of enallylpropymal (5‐allyl‐5‐isopropyl‐1‐methylbarbituric acid), C₁₁H₁₆N₂O₃, is composed of centrosymmetric N—H...O hydrogen‐bonded dimers, while 1,5‐di(but‐2‐enyl)‐5‐ethylbarbituric acid, C₁₄H₂₀N₂O₃, forms N—H...O hydrogen‐bonded helical chains. Each of the ten known crystal structures of closely related N‐monosubstituted derivatives of barbituric acid displays one of the fundamental N—H...O hydrogen‐bonded motifs of the two title structures, i.e. either a dimer or a chain.     

Spectroscopic Studies and Crystal Structure of 4-(2-Hydroxy-3-Methoxybenzylideneamino)-<Emphasis Type="Italic">N</Emphasis>-(5-Methylisoxazol-3-yl) Benzenesulfonamide

Abstract  

Schiff base 4-[(2-hydroxy-3-methoxybenzylideneamino)-N-(5-methylisoxazol-3-yl)benzene-sulfonamide has been synthesized from the reaction of 4-amino-N-(5-methylisoxazol-3-yl)benzenesulfonamide(sulfamethoxazole) with 2-hydroxy-3-methoxybenzaldehyde. It has been characterized by elemental analysis, MS, IR, ¹H NMR, ¹³C NMR, HETCOR and UV–Visible techniques. The structure of it also has been examined crystallographically. For the compound exist as dominant form of enol-imines in both the solid state and the solutions. It crystallizes in the monoclinic space group P2₁/c with a = 8.2694(7), b = 8.3453(5), c = 26.260(2) ?, β = 97.142(7) °, V = 1798.1(2) ?³, D _x  = 1.431 g cm⁻³, R ₁ = 0.0529 and wR ₂ = 0.1370 [I > 2σ(I)], respectively.     

Synthesis,Spectroscopic Studies and Structure of 2-[(Benzo[<Emphasis Type="Italic">d</Emphasis>]thiazol-2-ylamino)methyl]phenol

Abstract  

Schiff base (E)-2-[(benzo[d]thiazol-2-ylimino)methyl]phenol (1) has been synthesized from the reaction of 2-hydroxy-benzaldehyde with 2-aminobenzothiazole. The 2-[(benzo[d]thiazol-2-ylamino)methyl]phenol (2) was prepared reduction of the Schiff base 1 with sodium borohydride. The compounds 1 and 2 have been characterized by elemental analysis, FT-IR, ¹H-NMR, ¹³C-NMR and UV–visible spectroscopic techniques. The structure of the compound 2 has also been examined crystallographically. The compound 2 crystallizes in the monoclinic space group P2/c. The unit cell parameters were found as a = 10.017(1), b = 11.725(1), c = 10.341(1) ?, V = 1208.1(1) ?³, D _x = 1.409 g cm⁻³ and Z = 4. The crystal structure was solved by direct methods and refined by the full-matrix least squares method and found as R ₁ = 0.0308 and wR ₂ = 0.0818 for 2032 for the observed reflections [I > 2σ(I)].     

Anchor Effect on Pedal Motion Observed in Crystal Phase of an Azobenzene Derivative

Abstract  

Some molecules having a molecular skeleton similar to that of stilbenes and azobenzenes show orientational disorder in the crystals due to pedal motion. Heretofore, the orientational disorder through pedal motion has been observed for the compounds containing only two aromatic rings in the absence of bulky substituent groups. Here we report that the pedal motion can be detected even in the presence of a bulky substituent group to which orientational disorder becomes invisible as a result of anchor effect arising from phenoxyphtalonitrile group. X-ray crystallographic analysis of the compound, C₂₃H₁₈N₄O, reveals the existence of partially overlapped two pedal conformers. The compound crystallizes in the monoclinic space group P2₁/c with a = 12.9429(11) Å, b = 8.5075(5) Å, c = 21.063(2) Å and β = 123.155(6)°. Major pedal conformer is stabilized by weak C–H···O type hydrogen bond and C–H···π type edge-to-face interactions in solid state. Quantum chemical calculations at B3LYP/6-311G+(d,p) level suggest that the stabilization of the compound decreases with increasing deviation from the planar geometry of trans-azobenzene fragment.     

1,3-二吗啉基丙烷与Hg(Ⅱ)和Zn(Ⅱ)的配合物:合成、结构与抗菌研究

以1,3-二吗啉基丙烷(DMP)为配体合成了2个配合物:Hg(DMP)Cl₂(1)和Zn(DMP)Cl₂(2),并对其结构进行了表征。单晶X-射线结构分析表明,2个配合物中的金属离子都与2个N原子和2个Cl原子配位,形成扭曲四面体配位结构。配体和配合物对3种革兰氏阳性菌(S. aureus ATCC25923,E. faecalis ATCC23212和S. epidermidis ATCC34384)和3种革兰氏阴性菌(E. coli ATCC25922,P. aeruginosa ATCC27853和K. pneumonia ATCC70063)都具有抗菌活性,且在一定条件下,Hg(Ⅱ)配合物的抗菌活性超过了作为标准的磺胺异恶唑药物。