Bioinspired dynamic assemblies are fabricated using suitable metal ions and organic ligands. Coordination of non-chelating bidentate ligand with simple Pd(II) results in [PdnL2n]2n+-type of complexes (n= 2, 3, 4, 6, 12, 24, 30 and 48).1,2 Construction of binuclear [Pd2L4]4+ type complexes using one type of C-shaped bidentate ligand has been well explored in the last few decades. 3 On the other hand, mix-ligated metal-organic cages (MOCs) employing more than one type of ligands thereby introducing multiple functionalities in the cage structure is less known.4 Formation of mixture of products can be avoided by careful selection of the ligand components based on complementary shape, size, functionality, directionality and basicity.5 Simple Pd(II) allows the formation of discrete [Pd2(L)x(L')y]4+ (x=1, y=3 or x=y=2) type complexes when the appropriate combination of ligand components is used.6 Different strategies employed for preparation of mix-ligated MOCs includes donor site engineering, 7 guest templation,8 shape-complementarity.9 To expand the scope of shape-complementary assembly, we have designed a conformationally-flexible ligand (LA), which undergoes an adaptive self-assembly on combination with different rigid ligands (LB-LF). Thus we were able to prepare a series of [Pd2(LA)2(L')2]4+-type cages (L'=LB-LF). Further utilization of the self-assembled cages is under process. In future, we aim to expand the adaptive self-assembly of shape-complementary cages to construct mix-ligated multicavity cages.
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