Rational Construction of Porous Polymeric Cadmium Ferrocene-1,1′-disulfonates for Transition Metal Ion Exchange and Sorption

Porous pillared bilayer open coordination polymer {[Cd(bpp)2(O3SFcSO3)]·(CH3OH)2 ·(H2O)6}n 1 (Fc = ferrocene) and 3D porous coordination polymer {[Cd(bpy)2(O3SFcSO3)]·(CH3OH)4}n 2 have been assembled from Cd(NO3)2, ferrocene-1,1′-disulfonate, and bridging ligands 1,3-bis(4-pyridyl)propane (bpp) or 4,4′-bipyridine (bpy). Both of them show very special adsorption properties to copper salts. Along with the increase in the solution concentration of Cu(NO3)2, the percentage of adsorbed copper ions falls, but the percentage of exchanged central cadmium ions and the amount of adsorbed copper ions rises. In dilute solution, there mainly exists metal ion sorption, whereas both ion sorption and exchange are in charge of the whole progress in strong solution. Meanwhile, such materials could be used as ideal metal ion adsorbent toward some other metal cations, including of Pb2+, Zn2+, Mn2+, Co2+, Ni2+. However, when all these metal ions coexist in a mixture solution, the two ferrocenyl complexes selectively adsorb large amounts of only Pb2+ (for 1, 88.54%; for 2, 75.80%) and Cu2+ (for 1, 90.94%; for 2, 79.45%). Ion sorption and central cadmium ion exchange might be considered as being dominated by the coordination ability of metal ions to free functional groups, ionic radii of adsorbed metal ions, and the solution concentration of adsorbed metal salts. On the basis of the recognition of ion exchange, the center metal ion-exchange product of 2, {[Cd0.5Cu0.5(bpy)2(O3SFcSO3)]·(CH3OH)4}n 3, could be obtained by ion-exchange-induced single crystal to single crystal transformation.多孔柱状双层开放性配位聚合物 {[Cd(bpp)2(O3SFcSO3)]·(CH3OH)2 ·(H2O)6}n 1（其中 Fc 代表铁卡宾）以及三维多孔配位聚合物 {[Cd(bpy)2(O3SFcSO3)]·(CH3OH)4}n 2，均由 Cd(NO3)2、铁卡宾-1,1'-二磺酸、以及桥连配体 1,3-双(4-吡啶基)丙烷（bpp）或 4,4'-联吡啶（bpy）组装而成。这两种聚合物对铜盐展现出独特的吸附特性。随着 Cu(NO3)2 溶液浓度的增加，吸附铜离子的百分比下降，而交换中心镉离子的百分比以及吸附铜离子的量则上升。在稀释溶液中，主要存在金属离子吸附现象，而在浓溶液中，整个吸附过程由离子吸附和交换共同负责。同时，此类材料可作为理想的金属离子吸附剂，针对某些金属阳离子，包括 Pb2+、Zn2+、Mn2+、Co2+、Ni2+。然而，当这些金属离子共存在混合溶液中时，两种铁卡宾配合物仅对 Pb2+（1，88.54%；2，75.80%）和 Cu2+（1，90.94%；2，79.45%）进行选择性吸附。离子吸附和中心镉离子交换可能主要取决于金属离子与自由官能团的配位能力、吸附金属离子的离子半径以及吸附金属盐的溶液浓度。基于对离子交换的识别，通过离子交换诱导的单晶到单晶转变，可得到 2 的中心金属离子交换产物 {[Cd0.5Cu0.5(bpy)2(O3SFcSO3)]·(CH3OH)4}n 3。” }