A Family of Externally-Functionalised Coordination Cages
A Family of Externally-Functionalised Coordination Cages
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DOI：
10.3390/chemistry3040088
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发表时间：
2021-12-01
影响因子：
2.1
通讯作者：
Ward, Michael D.
中科院分区：
文献类型：
--
作者：
Jackson, Garrett D.;Tipping, Max B.;Ward, Michael D.
提出了一种已知的M8L12立方配位笼衍生物的新合成路线，在这种笼中，一系列不同的取代基连接在双（吡唑基吡啶）桥接配体两端的吡啶环的C-4位置上。取代基是(i) -CN基团（新配体L-CN）， (ii) -CH2OCH2-CCH（含末端炔）基团（新配体L(C)）；（iii） -(CH2OCH2)(3)CH2OMe（三乙二醇单甲基醚）基团（新配体L-PEG）。所得到的功能化配体与M2+离子（特别是Co2+， Ni2+, Cd2+）结合形成具有24个外部官能团的同结构[M8L12]（16+）笼核；对L- cn （M2+ = Cd2+）和L(C) （M2+ = Ni2+）笼进行了结晶学表征。这些的价值是双重的：(i)外部腈或烯烃取代基可以通过“点击”反应为进一步的合成机会提供基础，原则上允许笼外表面的多种功能化；（ii）外部-(CH2OCH2)(3)CH2OMe基团显著提高笼型在水和有机溶剂中的溶解度，允许在更大范围的条件下测量空腔结合客体的结合常数。
New synthetic routes are presented to derivatives of a (known) M8L12 cubic coordination cage in which a range of different substituents are attached at the C-4 position of the pyridyl rings at either end of the bis(pyrazolyl-pyridine) bridging ligands. The substituents are (i) -CN groups (new ligand L-CN), (ii) -CH2OCH2-CCH (containing a terminal alkyne) groups (new ligand L(C)); and (iii) -(CH2OCH2)(3)CH2OMe (tri-ethyleneglycol monomethyl ether) groups (new ligand L-PEG). The resulting functionalised ligands combine with M2+ ions (particularly Co2+, Ni2+, Cd2+) to give isostructural [M8L12](16+) cage cores bearing 24 external functional groups; the cages based on L-CN (with M2+ = Cd2+) and L(C) (with M2+ = Ni2+) have been crystallographically characterised. The value of these is twofold: (i) exterior nitrile or alkene substituents can provide a basis for further synthetic opportunities via 'Click' reactions allowing in principle a diverse range of functionalisation of the cage exterior surface; (ii) the exterior -(CH2OCH2)(3)CH2OMe groups substantially increase cage solubility in both water and in organic solvents, allowing binding constants of cavity-binding guests to be measured under an increased range of conditions.