ABSTRACT

Chiral fungicides R/S-metalaxyls(R/S-MTLs) and R/S-benalaxyls(R/S-BNLs) have different biotoxicity. It is very important to unravel molecular recognition and enantiomeric separation of R/S-MTLs or R/S-BNLs. In this paper, we designed a novel asymmetric ligand: 5-methoxy-2-(4-methoxy-6”-(quinazolin-2-yl)-[2,2”−bipyridin]-6-yl)quinazoline(MMQBQ), further constructed a new asymmetric receptor Uranyl-MMQBQ by coordination of MMQBQ with uranyl. The complexation and separation of receptor Uranyl-MMQBQ with guests R/S-MTLs or R/S-BNLs were systematically studied using density functional theory (DFT) method. The respects of ESP, MBO, RFC, LOL, EDDM, EST-NOCV, QTAIM, FMOs, IGMH, and Gibbs free energy changes were calculated and analyzed. The results indicated that the MMQBQ could form a stable receptor Uranyl-MMQBQ with uranyl, which could selectively recognize and separate chiral R/S-MTLs or R/S-BNLs by receptor’s U coordinating to carbonyl oxygens of guests. For R/S-MTLs, separation factors(SF_S/R) of Uranyl-MMQBQ were more than 16 in water, chlorobenzene, toluene, carbon tetrachloride and cyclohexane, enantioselectivity coefficients(ESCs) ranged of 99.92%-94.24% in the above four solvents. While for R/S-BNLs, ESCs of Uranyl-MMQBQ were over 99% and SF_S/R values were a range of 533.97–2839.36 in the above organic solvents. The findings provide valuable information for design of novel uranyl ligand and its complexes, meanwhile supply useful guidance for experiments on separation of other chiral fungicides in environmental protection.

摘要

手性杀菌剂R/S-甲霜灵(R/S-MTLs)和R/S-苯霜灵(R/S-BNLs)具有不同的生物毒性。阐明 R/S-MTL 或 R/S-BNL 的分子识别和对映体分离非常重要。在本文中，我们设计了一种新型不对称配体：5-甲氧基-2-(4-甲氧基-6”-(喹唑啉-2-基)-[2,2”−联吡啶]-6-基)喹唑啉(MMQBQ)等人通过MMQBQ与铀酰的配位进一步构建了新的不对称受体Uranyl-MMQBQ。采用密度泛函理论（DFT）方法系统研究了受体Uranyl-MMQBQ与客体R/S-MTLs或R/S-BNLs的络合和分离。对ESP、MBO、RFC、LOL、EDDM、EST-NOCV、QTAIM、FMOs、IGMH、Gibbs自由能变化方面进行了计算和分析。结果表明MMQBQ可以与铀酰形成稳定的受体Uranyl-MMQBQ，它可以通过受体的U与客体的羰基氧配位来选择性地识别和分离手性R/S-MTL或R/S-BNL。对于 R/S-MTL，分离因子（Uranyl-MMQBQ在水、氯苯、甲苯、四氯化碳和环己烷中的SF _S/R )均大于16，对映选择性系数( ESC s)在上述四种溶剂中的范围为99.92%-94.24%。而对于 R/S-BNL， Uranyl-MMQBQ 在上述有机溶剂中的ESC超过 99%，SF _S/R值在 533.97-2839.36 范围内。该研究结果为新型铀酰配体及其配合物的设计提供了有价值的信息，同时也为其他环保手性杀菌剂的分离实验提供了有益的指导。