Yu Xiaoqi

Metallomicellar Catalysis: Phosphodiester Hydrolysis Catalyzed by Cu(II), Zn(II), Ni(II), and Co(II) Complexes of Chelating Pyridyl Donor Ligands in CTAB Micellar Solution

The syntheses of two alkanol‐pyridyl ligands, 6‐(n‐dodecyloxymethyl) ‐2‐(hydro‐xymethyl)pyridine (1) and 6‐(methyloxymethyl)‐2‐(hydroxymethyl)pyridine(2), are reported. Metallomicellar systems made of complexes of these ligands with Cu(II), Zn(II), Ni(II), and Co(II) in the presence of surfactant CTAB are efficient catalyzers in the hydrolysis of bis(p‐nitrophenyl)phosphate (BNPP). The experimental results indicate that 2∶1 ligand:metal ion complexes in CTAB micellar solution are the active species for the catalytic hydrolysis of BNPP. The ternary complex kinetic model for metallomicellar catalysis was employed to treat the results to obtain the relative kinetic and thermodynamic parameters. The results predicted the reasonability of such kinetic models.

HYDROLYSIS OF P-NITROPHENYL PICOLINATE CATALYZED BY COPPER(II ) COMPLEXES OF LONG ALKYL-PYRIDINES WITH HYDROXYL GROUPS IN MICELLAR SOLUTION

ABSTRACT The ternary complex kinetic model for metallomicellar catalysis was employed to investigate the effect of Zn2+ ion or Ni2+ion complexes of long alkyl-pyridines with hydroxyl groups in micellar solution on the hydrolysis of p-nitrophenyl picolinate in this paper. The kinetic and the thermodynamic parameters (K N, K r, K M) were obtained. More worthily, the effect of pH on the hydrolysis of p-nitrophenyl picolinate in metallomicellar phase was discussed quantitatively. The rate constant (K N) of the hydrolysis of p-nitrophenyl picolinate in metallomicellar phase was obtained and compared with Cu2+ ion complex system. The results indicated that Cu2+ ion micelle, Ni2+ ion micelle and Zn2+ ion micelle all exhibited great catalytic effects on the hydrolysis of p-nitrophenyl picolinate. and the order of activity is:Cu2+ ion micelle ≥ Ni2+ ion micelle ≥ Zn2+ ion micell. Moreover, the reasonability of the ternary complex kinetic model was verified further.

Micellar Catalysis of Composite Reactions II. The Effect of CTAB Micelles on the Alkaline Fading of Malachite Green

Abstract The alkaline fading of malachite green, which is interpreted as parallel first order and second order reactions, has been studied in cetyltrimethylammonium bromide (CTAB) micellar solution at 25°C using spectrophotometry. A micellar catalytic model is proposed in this paper for constant concentration of hydroxideion. For this model, the first order and the second order rate constants in CTAB micellar phase,k1m and k2m have been obtained. The experimental results indicate that the first order reaction of malachite green cation with water is catalysed by CTAB micelles while the second order reaction of malachite green cation with hydroxide ion is inhibited by CTAB micelles. The first order rate constant in CTAB micellar phase, k1m , is 210 times of that in the bulk phase, but the second order rate constant in CTAB micellar phase, k2m , is 0. 166 time of that in the bulk phase. The results are interpreted mostly in relation to the micellar micropolarity and electrostatic interaction. @Keywords: Mice...

The design and study of highly selective fluorescent probes for peroxynitrite

As one of the most important intracellular reactive oxygen species, peroxynitrite plays vital roles in various cellular processes such as the redox balance. On the basis of the work reported by our group, we designed and synthesized a series of fluorescent dyes based on the coumarin-quinolinium conjugates, and investigated their reactivities toward the reactive oxygen species. The results showed that in phosphate buffered saline (PBS), C-QL-1 and C-QL-2 could exhibit selective fluorescence intensity enhancements in the presence of peroxynitrite, with detection limits to be 69 and 140 nM, respectively. The oxidative cleavage and hydrolysis of the carbon-carbon double bond in the probes to form aldehyde was confirmed via 1H NMR and electrospray ionization mass spectrometry (ESI-MS).

The synthesis and application of a lysosome-targeted-fluorescent probe for the detection of biothiols

As an important member of bio-active species, biological thiols have been proved to play pivotal roles in cellular growth in cells. In this paper, we have designed and synthesized a new coumarin-based off-on fluorescent probe (Lyso-thiol ) for the selective detection of biothiols in aqueous solution and in living cells. Lyso-thiol has been prepared by a 2-step procedure using morpholine as the lysosome-targeting group. The probe has successfully realized the linear quantitative detection of biothiols in a relatively large concentration scope. Moreover, under the saturated concentration of the biological thiols, the fluorescence intensity of the probe can be enhanced by as much as 745 times. The intracellular experiments have also confirmed the low cytotoxity and exceptional biocompatibility of the probe. It is validated both in HeLa and HepG 2 cells that Lyso-thiol is capable of specifically targeting lysosome and vividly imaging biothiols in cellular level.

Micellar catalysis of composite reactions. I. Micellar effect on the consecutive first order reaction

ABSTRACT The micellar catalytic model (or the consecutive first order reaction has been proposed in this paper. It was applied to the alkaline hydrolysis of dimethyl phthalate in micellar solutions of surfactants (CTAB, SDS and Triton X-100), and the alkaline hydrolysis of bis (2,4-dinitrophenyl) posphate in CTAB micellar solution. Rate constants obtained in micellar phase indicate that the two steps of alkaline hydrolysis of dimethyl phthalate are both inhibited by all of the surfactants investigated. CTAB micelle exhibits a greater catalytic effect on the alkaline hydrolysis of bis (2, 4-dinitrophenyl) phosphate. this may be arised from the local concentration effect of hydroxide ion in CTAB micellar phase. Nevertheless. the second order rate constant of bis-(2, 4-dinitrophenyl) phosphate in the micellar phase is smaller than that in the bulk phase.