Metallomicellar catalysis: Hydrolysis of phosphate monoester and phosphodiester by Cu(II), Zn(II) complexes of pyridyl ligands in CTAB micellar solution

Cleavage of phosphate diesters mediated by Zn(II) complex in Gemini surfactant micelles

“…Thus, the true cause of the higher reactivity of HPNP catalytic cleavage in cationic micelles is attributed to the formation of plentiful substrate-catalyst complexes via a supposed "sandwich absorptive mode" (micelle-HPNP-catalyst mode), in which the negative HPNP molecule is sandwiched in the interlayer between the positive micelle and the catalyst. Despite that this proposed sandwich absorptive mode is not like those traditional metallomicelle models [13][14][15][16][17], it is still consistent with a pseudo-intramolecular reaction mechanism described in Section 3.2. Ultimately, the rate of HPNP cleavage mediated by ZnL shows 29.5 times and 12 times the magnitude rate acceleration in Gemini 16-2-16 micelles and CTAB micelles over that in the pure buffer solution, respectively.…”

Enhancing Phosphate Diester Cleavage by a Zinc Complex through Controlling Nucleophile Coordination

“…This rate constant is about 100‐fold lower than reported by Lloyd and Cooperman18 for the cleavage of N ‐methyl phosphorylimidazole (0.42 M −1 s −1 at 29.2 °C), but represents a 100‐fold greater rate acceleration, because the uncatalysed rate of hydrolysis of p NPP dianion is about 10 000‐fold slower than for phosphorylimidazole. The observation that 3 , a mononuclear zinc complex, catalyses the cleavage of p NPP, is unusual, because previous reports highlight the need of more complicated structures, such as in micellar or supramolecular catalysts 30. 31…”

Metallomicelles as potent catalysts for the ester hydrolysis reactions in water

“…This could be due to the involvement of 'supernucleophilic' DMAP moiety, although the reason for ligand 78 not showing esterolytic activity was not apparent. The involvement of Cu(II) ion enhanced the catalytic activity of all the ligands, but the tetradentate ligands (78)(79) were superior to those of the analogous tridentate ligands. All the ligands evidenced formation of complexes in 1:1 ligand to metal ion ratio (Scheme 12).…”

“…Jiang et al developed various ligands based on long alkanol imidazole [74], or pyridine moiety [75,76]. Imidazole containing ligands 82 and 83 showed good hydrolyzing ability in presence of Cu(II), Zn(II) and Ni(II) toward bis (p-nitrophenyl) phosphate (BNPP) [75].…”

“…Recently the catalytic effect of metallomicellar complex made up of ligands, 86-88 possessing hydrophobic methylene bridges embedded in CTAB medium was studied by Jiang et al These catalysts induced the hydrolysis of both the monoester NPP and diester BNPP in micellar media [78].…”