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Triangular exo-polydentate ligands have been frequently employed for the metal-directed assembly of coordination polyhedra. [1][2][3][4] By linking triangles at their corners or edges, a family of polyhedral structures can in principle be engaged at will. Here, we design a triangular panel-like ligand with four donor sites on the two edges of the triangle (two donor sites on each edge): namely, compound 1 in Scheme 1. Having two-point binding sites on its two edges, this triangular unit is expected to assemble into edgesharing polyhedral entity upon complexation with (en)Pd(NO 3 ) 2 (2), which is a versatile 90°coordination unit for metal-directed assembly. Whereas previous triangular ligands all possess C 3 symmetry, 1-4 panel 1 is C 2 -symmetric and hence can be linked in two different ways: parallel and antiparallel links. Interestingly, these two options were perfectly controlled by the guests. 5 We show that some large guests induce the parallel link of the triangles leading to open cone (tetragonal pyramidal) structure 3, whereas antiparallel link is selected by some small tetrahedral guests giving closed tetrahedron structure 4 (Scheme 1). Both assemblies have the same M 8 L 4 composition and, therefore, constitute a dynamic receptor library 6,7 from which each receptor is selected by its optimal guests.The quantitative assembly of M 8 L 4 open cone 3 was induced by large guest molecules such as dibenzoyl (5). Thus, ligand 1