Anion recognition and sensing of ruthenium(II) and cobalt(II) sulfonamido complexes.

A series of artificial receptors, based on a sulfonamido system, have been designed and synthesized. The interaction of these receptors with biologically important anions was determined by UV-vis, (1)H NMR titration and electrochemical experiments. Results indicate that these receptors show high recognition abilities for fluoride (F(-)) or acetate (AcO(-)), moderate affinities for dihydrogen phosphate (H(2)PO(4)(-)) or hydroxyl (OH(-)) and almost no affinities for chloride (Cl(-)), bromide (Br(-)) or iodide (I(-)). (1)H NMR titration shows that the interaction between the receptors and anions depends on the hydrogen-bond formation. The Co(III)/Co(II) redox signals of receptor and disappear gradually when the fluoride or acetate anions are added. Moreover, visual color changes accompany guest binding, enabling this system to act as colorimetric anion sensors. The colorimetric properties of these sensors are ascribed to the hydrogen-bond formation and the colorimetric group quinoxaline.

A highly selective naked-eye colorimetric sensor for acetate ion based on 1,10-phenanthroline-2,9-dicarboxyaldehyde-di-(p-substitutedphenyl-hydrazone).

A new and simple colorimetric sensor with high selectivity for acetate ion based on 1,10-phenanthroline-2,9-dicarboxyaldehyde-di-(p-substitutedphenylhydrazone) receptor 2 has been synthesized. The selectively binding ability of receptor 2 to acetate ion over other anions tested was demonstrated by UV-vis absorption spectroscopy in DMSO. Comparing with other anions studied, the UV-vis absorption spectrum in dimethyl sulfoxide shows significant response toward acetate ion with high selectivity, and meanwhile dramatic color change is observed from yellow to green in the presence of acetate ion (5 x 10(-6)mol/L). Little UV-vis absorption spectrum change has occurred when receptor 2 was titrated with other different guest (F(-), Cl(-), Br(-), I(-), H(2)PO(4)(-) and OH(-)). In addition, the (1)H NMR spectrum titration shows deprotonation of the receptor in the presence of acetate ion.

A simple and efficient colorimetric anion sensor based on a thiourea group in DMSO and DMSO-water and its real-life application.

An efficient colorimetric sensor with a thiourea moiety as binding sites and p-nitrophenylhydrazine as a signaling unit has been synthesized by only one single-step procedure. Selectivity for anions with the distinct geometry (tetrahedral, trigonal planar and spherical) has been investigated in dry DMSO and even in DMSO/H(2)O (95:5, v/v) solutions through the naked-eye experiment, UV-vis titration and (1)H NMR titration techniques. In particular, the fluoride of toothpaste can be detected qualitatively by the sensor 1.

A phenylhydrazone-based indole receptor for sensing acetate.

A novel phenylhydrazone-based indole anion receptor is synthesized by a simple method, and the receptor binds acetate anions with good selectivity in DMSO solution, which is related to the structure of the receptor matching with the anion. The binding properties of the host are examined by UV-vis changes. The color changes of the host upon the addition of a variety of structurally different anions were also utilized as nake-eyed recognization (from orange to purple, first figure), The hydrogen bonds between recognization sites (phenylhydrazone and indole N-H) and anions were determined on the basis of (1)H NMR experiments.

A simple and efficient colorimetric anion receptor for H(2)PO(4)(-).

A novel and neutral anion sensor bearing a urea group as binding sites and 2,4-di nitrophenylhydrazine unit as a molecular architecture and a chromophore was synthesized and the visible color changes, the UV-vis and (1)H NMR spectral responses toward anions were assessed.

Studies on synthesis and anion recognition properties of (3'-nitrobenzo)[2,3-d]-(3''-nitrobenzo)[9,10-d]-1,4,8,11-tetraazacyclotetradecane-5,7,12,14-tetraone.

A novel artificial receptor, (3'-nitrobenzo)[2,3-d]-(3''-nitrobenzo)[9,10-d]-1,4,8,11-tetraazacyclotetradecane-5,7,12,14-tetraone, was designed and synthesized. The interactions of this receptor with different anions were determined by UV-vis and (1)H NMR titration experiments, and their affinity constants to different anions were compared with those of other similar/different systems. The results indicated that this receptor showed a high selective and recognitive ability for F(-) among F(-), Cl(-), Br(-), I(-), AcO(-), OH(-), and H(2)PO(4)(-). Moreover, the low energy configuration of this receptor was further determined by means of theoretical investigations.

Effects of the receptors bearing phenol group and copper(II) on the anion recognition and their analytical application.

Two novel artificial receptors based on diamide and bearing phenol group and copper(II) have been synthesized. Their anion-binding properties are evaluated for F(-), Cl(-), Br(-), I(-), AcO(-), H(2)PO(4)(-) and OH(-) by UV-vis and (1)H NMR titration experiments to further elucidate the impact of phenol group and copper(II) on the chemistry of anion-recognition. Results indicate that the interacted model of fluoride anion with receptor 1 is different from other anions and the (1)H NMR signals of receptor 2 occur changes after the addition of fluoride anion. This may be related with the small radius and strong electronegative property of fluoride. The receptors should have many chemical and analytical applications and the sensing principle should be widely applicable to the sensing of other receptors.

Synthesis, characterization and biological activity of lanthanum(III) complexes containing 2-methylene-1,10-phenanthroline units bridged by aliphatic diamines.

Two novel lanthanum(III) complexes containing 2-methylene-1,10-phenanthroline units bridged by aliphatic diamines were synthesized and characterized by elemental analysis, IR, NMR, thermal analysis and conductance measurements. They have been assayed for anticancer activity in vitro against HL-60 (human leukocytoma) cells, PC-3MIE8 (human prostate carcinoma) cells, BGC-823 (human stomach carcinoma) cells, MDA-MB-435 (human galactophore carcinoma) cells, Bel-7402 (human liver carcinoma) cells, and Hela (human cervix carcinoma) cells. The results show that the two complexes exhibit good cytotoxic activities against different cell lines in general, especially more effective than cisplatin against Bel-7402, BGC-823 and MDA-MB-435 cell lines. DNA-binding studies indicate that, besides the intercalation, the complexes bind to DNA by the other interaction(s), which might be responsible for the production of more compact DNA, coinciding with more A-like feature of DNA as suggested by CD spectra.

Spectroscopic properties, catalytic activities and mechanism studies of [(TpPh)Co(X)(CH3OH)m] . nCH3OH: bicarbonate dehydration in the presence of inhibitors.

Two inhibitor-containing 'half-sandwich' cobalt(II) complexes [(TpPh)Co(X)(CH3OH)m] x nCH3OH ((TpPh) = hydrotris (3-phenylpyrazolyl)borate; 1: X- = N3-, m = 1, n = 2; 2: X- = NCS-, m = 0, n = 0) have been synthesized and used as the catalysts in the bicarbonate dehydration reaction. The structures of 1 and 2 were determined by X-ray diffraction analysis, which shows that N3- and NCS- coordinate to the Co(II) ions of 1 and 2, respectively, with the Co-N bond lengths of 1.992(6) A and 1.901(3) A. The coordination geometries of the Co(II) complexes in solution are five-coordinated trigonal bipyramid as revealed by the spectroscopic measurements. The dehydration kinetic measurements of HCO3- are performed by the stopped-flow techniques at pH < 7.9. The apparent dehydration rate constant k(obs) varies linearly with Co(II) complex and H+ concentrations, respectively, and the catalytic activity of 2 is lower than that of 1. The aqua Co(II) complex must be the reactive catalytic species in the catalyzed dehydration reaction and the rate-determining step is the substitution of the labile water molecule by HCO3-. The k(obs) values increase with increasing reaction temperature, and the large negative entropy of activation also indicates the associative activation mode. The inhibition ability of NCS- is stronger than that of N3-, which can be rationalized by the decreases in the Co-N(N3-/NCS-) bond lengths and effective atomic charges of the Co(II) ions based on the X-ray crystallographic data and theoretical calculations in this work.

The different roles of metal ions and water molecules in the recognition and catalyzed hydrolysis of ATP by phenanthroline-containing polyamines.

The phenanthroline bridging polyaza ligands L1, L2 and L3 can selectively and strongly bind nucleotides at physiological pH, and hence accelerate the hydrolysis rate of the bound ATP. It is interesting that a phosphoramidate intermediate at 2.88 ppm (should be added 5.63 ppm when compared with other models) was found in the hydrolysis process of L/ATP. By introduction of metal ions (critical Zn(2+) or hard Mg(2+), Ca(2+)) to the L/ATP system, recognition of the anionic substrates by the protonated ligands was greatly promoted. However, due to the different affinities of metal ions to the receptor and the substrate, ATP hydrolysis in Zn(2+)/L/ATP system and Mg(2+)(Ca(2+))/L/ATP system occurs through different mechanisms. By comparison with the M/ATP (M=Zn(2+), Mg(2+), Ca(2+)) system, the rates of ATP-hydrolysis in the Mg(2+)Ca(2+)/L/ATP system and the Zn(2+)/L/ATP system were enhanced and retarded, respectively. Moreover, the reasons contributing to large rate range of the L/ATP systems and M(2+)/L/ATP systems were given. The results show that metal ions vertically regulate the recognition and hydrolysis of ATP. On the other hand, water molecule participates in the hydrolysis reactions at different steps with different functions in the L/ATP systems and M(Zn(2+), Mg(2+), Ca(2+))L/ATP systems.

Kinetic study of the effects of inhibitors on the catalyzed dehydration of HCO3- by copper(II) complexes [TpPh]CuX (X- = OH-, N3-, NCS-).

A series of half-sandwich copper(II) complexes [TpPh]CuX ([TpPh] = hydrotris(3-phenyl-pyrazolyl)borate; X- = OH- (1), N3- (2), NCS- (3)) have been synthesized as models for carbonic anhydrase. The structure of 3 was determined by X-ray diffraction analysis. Crystals of 3 (C37H30BCuN9S) are triclinic, space group P1 with a = 11.997(3) A, b = 12.116(3) A, c = 13.384(4) A, alpha = 81.088(5) degrees, beta = 79.289(6) degrees, gamma = 68.668(5) degrees, V = 1772.4(8) A3, and Z = 2. The dehydration kinetic measurements of HCO3- are performed by the stopped-flow techniques at pH < 7.9. The apparent dehydration rate constant kdobs varies linearly with total Cu(II) concentration, and the catalytic activity of the model complexes decreases in the order 1 > 2 > 3. The catalytic activity decreases with increasing pH indicating that the aqua model complex must be the reactive catalytic species in the catalyzed dehydration reaction and the rate-determining step is the substitution of the labile water molecule by HCO3-. The kdobs values increase with increasing reaction temperature, and the apparent activation energies of the model complexes with inhibitors are remarkably higher than that of the complex with no inhibitors, this being the origin of inhibition. The large negative entropy of activation also indicates an associative mode of activation in the rate-determining step. The inhibition ability of the inhibitor NCS- is stronger than that of the inhibitor N3-, which can be rationalized by the decrease in effective atomic charges of the Cu(II) ions as revealed by the theoretical calculations.

Spectroscopy, cytotoxicity and DNA-binding of the lanthanum(III) complex of an L-valine derivative of 1,10-phenanthroline.

The interaction of the lanthanum(III) La(III)-L (L=N,N'-bis-(1-carboxy-2-methylpropyl)-1,10-phenanthroline-2,9-dimethanamine) complex with calf thymus DNA was studied by electronic spectra, fluorescence spectra and circular dichroic spectra. The La(III)-L complex was assayed for antitumor activity in vitro against the HL-60 (the human leucocytoma) cells, HCT-8 (the human coloadenocarcinoma) cells, BGC-823 (the human carcinoma of stomach) cells, Bel-7402 (the human liver carcinoma) cells and KB (the human nasopharyngeal carcinoma) cells. The results show that the La(III)-L complex has activity against HL-60 cells, Bel-7402 cells and KB cells. Moreover, it is slightly more effective against Bel-7402 cell line than cisplatin. Using ethidium bromide as a fluorescence probe, the binding mode of the La(III)-L complex to calf-thymus DNA was studied spectroscopically. For comparison, the same measurements were carried out with La(III)-Phen [La(III)-1,10-phenanthroline complex] and La(III)-Val [La(III)-L-valine complex]. The results indicate that the La(III)-L and La(III)-Phen complexes possibly interact with calf-thymus DNA by both intercalative and coordination binding, whereas the La(III)-Val complex interacts with calf-thymus DNA by coordination binding. Kinetics of binding of the three complexes to DNA is for the first time studied using ethidium bromide as a fluorescence probe with stopped-flow spectrophotometer under pseudo-first-order condition. The strong two-step mechanisms in the process of the La(III)-L and La(III)-Phen complexes and one step in the process of the complex La(III)-Val interacting with DNA are observed, and the k(obs) (observed pseudo-first-order rate constant) and E(a) (observed energy of activation) values of binding to DNA are obtained.