物理化学学报 >> 2017, Vol. 33 >> Issue (12): 24802480-2490.doi: 10.3866/PKU.WHXB201706122

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席夫碱Cu(Ⅱ)络合物的超分子螺旋手性及其手性光谱

曹石,曾丽丽,谢菁,万仕刚,李丹,章慧*()   

  • 收稿日期:2017-05-05 发布日期:2017-09-05
  • 通讯作者: 章慧 E-mail:huizhang@xmu.edu.cn
  • 基金资助:
    国家自然科学基金(21273175)

Supramolecular Helical Chirality of Schiff Base Copper(Ⅱ) Complexes and Their Chiroptical Spectroscopy

Shi CAO,Li-Li ZENG,Jing XIE,Shi-Gang WAN,Dan Li,Hui ZHANG*()   

  • Received:2017-05-05 Published:2017-09-05
  • Contact: Hui ZHANG E-mail:huizhang@xmu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21273175)

摘要:

本文通过不同的手性二胺(pn=1,2-丙二胺、chxn=1,2-环己二胺、dpen=1,2-二苯基乙二胺)与脱氢乙酸(dha)缩合,获得了N2O2型手性席夫碱配体(dha-en),进而合成了相应的三对手性席夫碱Cu(Ⅱ)络合物([Cu(dha-R/S-pn)](1a和1b)、[Cu(dha-R,R/S,S-chxn)](2a2b)、[Cu(dha-R,R/S,S-dpen)](3a3b),对其进行的固体和溶液电子圆二色(ECD)及溶液振动圆二色(VCD)光谱测试表明,这些化合物在固体和溶液状态下的金属中心的主要配位模式和绝对构型基本一致。此外,通过单晶结构分析发现:对于络合物2a/2b以及3a/3b,中心金属Cu(Ⅱ)除了与手性dha-en四齿配位外,还与相邻分子内酯环上的羰基发生弱的轴向配位形成一维超分子螺旋链,即实现了配位键构筑的席夫碱络合物的手性超分子自组装。本文对两对手性络合物2a/2b以及3a/3b的手性结构基元及其与超分子螺旋之间的关系进行了讨论。将本文所获实验VCD光谱数据与文献报道的相关数据进行比对分析,可以相互印证,并呈现一定的绝对构型关联规律且具有手性配位立体化学结构的指纹特征。

关键词: 席夫碱Cu(Ⅱ)络合物, 电子圆二色, 振动圆二色, 单晶结构, 超分子手性组装

Abstract:

Three pairs of N2O2-type Schiff base ligands were synthesized by condensing dehydroacetic acid (dha) with chiral 1, 2-diaminopropane (pn), trans-1, 2-diaminocyclohexane (chxn), and 1, 2-diphenylethylenediamine (dpen). These chiral ligands were used to coordinate copper(Ⅱ) ions to produce the corresponding Schiff base Cu(Ⅱ) complexes:[Cu(dha-R/S-pn)] (1a and 1b), [Cu(dha-R, R/S, S-chxn)] (2a and 2b), and[Cu(dha-R, R/S, S-dpen)] (3a and 3b). Detailed analyses using electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectroscopies reveal that these Schiff base Cu(Ⅱ) complexes retain the main coordination modes and the absolute configurations of the metal centers, both in solution and the solid state. In addition, according to the crystal structures, the central Cu(Ⅱ) ions of 2a/2b and 3a/3b were found to not only coordinate to the chiral dha-en ligands, but were also axially coordinated to the carbonyl groups of the contiguous lactonic rings, providing one-dimensional supramolecular helical chains through self-assembly. In this work, we deeply studied the relationship between the chiral coordination units and the supramolecular helical structures of 2a/2b and 3a/3b. By comparing our experiment VCD spectroscopic data with related VCD spectral features reported in the literature, a specific correlation between the VCD spectral properties and absolute configurations was investigated, which provided fingerprint characteristics for chiral coordination structure.

Key words: Schiff base Cu(Ⅱ) complex, Electronic circular dichroism, Vibrational circular dichroism, Single-crystal structure, Supramolecular chiral assembly

MSC2000: 

  • O641