无溶剂研磨合成双核席夫碱配合物及多组分自分类行为

Self-Sorting of Binuclear Schiff-Base Complexes under Solvent-Free Grinding Conditions

利用手动研磨法在无溶剂条件下通过1,4-二(咪唑-2-甲醛)丁烷(A)、2,4-二亚甲基-二(咪唑-2-甲醛)-三甲基苯(B)、2,5-二亚甲基-二(咪唑-2-甲醛)-对-二甲苯(C)中的任一组分与N-乙基乙二胺(D)和三氟甲磺酸亚铁组装合成3个Fe(Ⅱ)席夫碱配合物1、2和3。X射线单晶衍射表明,配合物1结晶于空间群Cmca,2和3结晶于空间群P21/c。1~3中每个Fe(Ⅱ)与配体中6个氮原子配位形成变形八面体FeN_6配位环境;每个双臂六齿配体螯合2个亚铁离子,而每个亚铁离子被2条配体包裹形成Fe_2L_2型双核配合物。基于以上配合物的合成,我们详细研究了混合多组分间的固态自分类行为。研究表明,多组分[D+A+B+Fe^(2+)]或[D+A+C+Fe^(2+)]发生自恋型自分类;而多组分[D+B+C+Fe^(2+)]发生群体型自分类,形成了一个由2个不同类型配体构筑的Fe2LL′杂配型配合物4,同时X射线单晶衍射确证了4的结构。此外,通过与溶液中自分类的对比,我们发现该体系固态自分类表现出更为高效的特点。

Three binuclear iron（Ⅱ） imidazole Schiff-base complexes were constructed by one-pot multicomponent assembly of di（imidazole aldehyde）（A-C）, 2-aminoethyl （ethyl） amine（D） and Fe（OTf）2 under solvent-free grinding conditions. X-ray crystallography revealed that the three complexes crystallized in different space groups of Cmca for 1, P21/c for 2-3. And the molecular structures of 1-3 all display Fe2L2 arrangement. In complexes 1-3, two ligand strands wrap around two Fe^2＋ ions and the Fe2＋ ions are coordinated to chelating moieties from two imidazole nitrogen atoms and four amine nitrogen atoms, resulting in the pseudo octahedral FeN6 coordination geometry. Taking advantage of the facile approach above, we then investigated the discrimination abilities of the multicomponent assembly process under the solvent-free condition when different components were mixed together （a mixture of D, two kinds of di（imidazole aldehyde） of A-C and Fe（OTf）2）. In this assemble system, combinations[D＋A＋B＋Fe^2＋] or[D＋A＋C＋Fe^2＋] adopt narcissistic self-sorting with only two species, while social self-sorting took place in the combination[D＋B＋C＋Fe^2＋] forming the single heteromer 4, which was composed of two different ligands and exhibited Fe2LL＇ arrangement. The structure of 4 was further verified by the X-ray analysis by preparing the single crystal of the heteromer 4. To compare the efficiency of solvent-free grinding solid self-sorting against the solution self-sorting, the conventional solution-based self-sorting reactions were also performed using the same starting materials with equal amount. In consequence of the complexity of ^1H NMR peaks of mixture, the selectivity is poor in solution. Overall, compared with self-sorting in solution, the solvent-free grinding self-sorting is more efficient due to the certain restrictions of molecular movement.