Template Control over Dimerization and Guest Selectivity of Interpenetrated Coordination Cages

Abstract

We have previously shown that the self-assembly of dibenzosuberone-based bis-monodentate pyridyl ligands L(1) with Pd(II) cations leads to the quantitative formation of interpenetrated coordination cages [BF4@Pd4L(1)8]. The BF4(-) anion inside the central cavity serves as a template, causing the outer two pockets to show a tremendous affinity for allosteric binding of two small chloride anions. Here we show that derivatization of the ligand backbone with a bulky aryl substituent allows us to control the dimerization and hence the guest-binding ability of the cage by the choice of the templating anion. Steric constraints imposed by L(2) prevent the large BF4(-) anion from serving as a template for the formation of interpenetrated double cages. Instead, a single isomer of the monomeric cage [Pd2L(2)4] is formed. Addition of the small anionic template Cl(-) permits dimerization, yielding the interpenetrated double cage [Cl@Pd4L(2)8], whose enlarged outer pockets show a preference for the binding of large anions such as ReO4(-).

Tuning the coordination chemistry of cyclotriveratrylene ligand pairs through alkyl chain aggregation

“…17 The tailoring of organic ligands and assembly conditions allows the chemist to exercise a degree of control over their self-assembly. [18][19] Fujita and co-workers, for example, have demonstrated an intricate system where small alterations to bridging ligand bite angle are enough to effect a large structural change between M 12 L 24 and M 24 L 48 polyhedra. 20 Likewise, the groups of Stang and Yamaguchi have shown how multi-ligand systems can undergo reversible exchange at room temperature to afford a variety of products.…”

Vertical Assembly of Giant Double‐ and Triple‐Decker Spoked Wheel Supramolecular Structures

“…All images of two gels showed the bulk networks, which were formed by the intermolecular interaction (i.e., π–π stacking and hydro-phobic interactions), [15b,23] and sol-gel phase transitions were rationalized by the ability of the organometallic gels based on metal-ligand bonds and noncovalent interactions to dynamically assemble or disassemble by varying temperature. [24] …”

Ion and Molecular Recognition Using Aryl–Ethynyl Scaffolding

“…Adding Cl − drove formation of a [M 2 L 4 ] 2 8+ interlocked cage with Cl − trapped inside the smaller central cavity. [72] The smaller central cavity leaves more space in the outer cavities, and the weakly bound BF 4 − undergoes ion exchange with ReO 4 − , to give the final structure [Pd 2 L 4 ] 2 [Cl] [ReO 4 ] 2 5+ . Photoswitchable ligand 22 forms a stable [M 2 L 4 ] 4+ cage upon addition of Pd 2+.…”