基于D-(—)-/L-(+)-对羟基苯甘氨酸的两对手性钴配合物的合成、晶体结构和电化学识别

采用常温溶液挥发法，以D-(—)-/L-(+)-对羟基苯甘氨酸(D-/L-Hhpg)为主配体，2种含氮吡啶配体4，4′-联吡啶(4，4′-bipy)和5，5′-二甲基-2，2′-联吡啶(5，5′-BM-2，2′-bipy)为辅助配体，与CoCl₂·6H₂O反应合成了2对手性配合物{[Co (D-hpg)(4，4′-bipy)(H₂O)]Cl·H₂O}_n(1-D)、{[Co (L-hpg)(4,4′-bipy)(H₂O)]Cl·H₂O}_n(1-L)、[Co (D-hpg)2(5，5′-BM-2，2′-bipy)]Cl·5.5H₂O (2-D)、[Co (L-hpg)₂(5，5′-BM-2，2′-bipy)]Cl·5.5H₂O (2-L)。通过单晶X射线衍射、元素分析、红外光谱、粉末X射线衍射等多种测试方法对其结构进行分析和表征。配合物的单晶X射线衍射数据表明，配合物1-D和1-L属于单斜晶系，P2₁手性空间群，分别呈现1D左手螺旋链和右手螺旋链，通过4，4′-bipy分子扩展为2D网状矩形格子结构。配合物2-D属于单斜晶系，P2₁手性空间群，为0D小分子，在氢键的作用下形成1D超分子双链，并以ABAB形式在a轴方向堆积排布。这些配合物的结构差异归因于辅助配体和Hhpg配位模式的影响。此外，还研究了配合物的电化学性质。配合物1-D表现出电化学可逆的氧化还原行为，并可作为电化学传感器用于有效地检测组氨酸对映体和定量测定组氨酸混合物中的对映体过量。

Two pairs of chiral cobalt enantiomeric coordination compounds based on D-(—)-/L-(+)-4-hydroxyphenylglycine: Synthesis, crystal structures, and electrochemical recognition

Two pairs of chiral coordination compounds {[Co(D-hpg)(4,4′-bipy)(H₂O)]Cl·H₂O}_n (1-D), {[Co(L-hpg)(4,4′ -bipy)(H₂O)]Cl·H₂O}_n (1-L), [Co(D-hpg)₂(5,5′-BM-2,2′-bipy)]Cl·5.5H₂O (2-D), and [Co(L-hpg)₂(5,5′-BM-2,2′-bipy)] Cl·5.5H₂O (2-L), where D-Hhpg=D-(-)-4-hydroxyphenylglycine, L-Hhpg=L-(+)-4-hydroxyphenylglycine, 4,4′-bipy= 4,4′-bipyridine, 5,5′-BM-2,2′-bipy=5,5′-dimethyl-2,2′-bipyridine, have been successfully synthesized. Their structures were determined by single-crystal X-ray diffraction analysis and characterized by elemental analysis, X-ray photoelectron spectra, infrared spectroscopy, solid-state circular dichroism spectra, thermogravimetric analysis, powder X-ray diffraction, and electrochemical methods. Compounds 1-D and 1-L feature 2D (4,4) rectangular grid networks that consist of left-or right-handed helical chains. Compounds 2-D and 2-L exhibit 0D molecule structures, and further 1D supramolecular double chains are formed by hydrogen bonding. The differences in the structures of these compounds are attributed to the influence of ancillary N-donor ligands and the coordination modes of Hhpg.Moreover, compound 1-D displays electrochemically reversible redox behavior, and serves as an electrochemical sensor for efficiently detecting histidine (His) enantiomers and quantitatively determining the enantiomeric excess in the His mixture.