ИСТИНА

Metal-organic frameworks (MOFs) based on porphyrins are promising class of porous materials possessing high crystallinity, different topological types and large variety of functions due to the tunable physico-chemical properties of macrocycle molecule. The examples of phosphonate-substituted porphyrin-based MOFs are limited despite phosphonates have high tendency to form strong interactions with different metal ions and multiple hydrogen bonds. The development of the efficient synthetic approaches towards porphyrinylphosphonate-based MOFs along with the revealing of their structural features is a great scientific challenge for new functional materials. Here we report the unusual structural features of two new topologically different zinc MOFs based on nickel(II) and palladium(II) 5,10,15,20-tetrakis(4-(phosphonatophenyl)porphyrinates, IPCE-1Ni and IPCE-1Pd, which were obtained under the same reaction conditions. Despite the two porphyrin linkers represent the same square tetraphosphonic node, they form different MOF structures. Single crystal XRD revealed that IPCE-1Ni has a very unusual topology, where only three of four phosphonate groups take part in the framework formation and each porphyrin molecule acts as a tritopic linker. In the case of IPCE-1Pd all four phosphonate moieties of porphyrin are connected with zinc cations. 3D network of IPCE-1Ni has a binodal (3,6)-connected flu-3,6-C2/c topology with discrete dinuclear secondary building unit (SBU) Zn2(PO2OH)4(PO3)2 while in IPCE-1Pd inorganic SBUs are isolated Zn2+ ions. The framework IPCE-1Pd has topologically equival organic and inorganic nodes and uninodal 4-connected net 4/4/o18 topology. Thus we have found intriguing structural differences in the class of porphyrinylphosphonates MOFs which are not typical for widely studied porphyrinylcarboxylates MOFs.