Synthesis, temperature-controlled structures and polyphenol oxidase activities of dinuclear manganese(II) complexes with N,N,N鈥?N鈥?tetrakis(2鈥?benzimidazolylmethyl)-1,4-diethylene amino glycol ether
摘要
Three dinuclear Mn(II) complexes, [Mn2(EGTB)(NO3)2(H2O)4](NO3)2 (1), [Mn2(EGTB)(NO3)4] (2) and [Mn2(EGTB)(NO3)(H2O)](NO3)3 (3) (EGTB = N,N,N鈥?N鈥?tetrakis(2鈥?benzimidazolylmethyl)-1,4-diethylene amino glycol ether) were prepared and characterized. Their crystal structures revealed a relationship between synthesis temperature and structure. With increasing the reaction temperature from 60 to 120 掳C or 160 掳C, the Mn-Mn distances are shortened from 14.019 脜 in 1, 7.662 脜 in 2 to 5.662 脜 in 3. Additionally, polyphenol oxidase (PPO) activity of those three complexes was studied by measuring the rate of increase in absorbance at 320 nm of pyrogallol substrate. At pH 7.8 and 30 掳C, the turnover numbers are 5.58 h鈭? for 1, 11.38 h鈭? for 2 and 13.97 h鈭? for 3, respectively. Furthermore, in pH 7.8-8.2, their catalytic activity increased with rising pH.