Molecular Paneling by Coordination: An M15L6 Hexahedral Molecular Capsule having Clefts for Reversible Guest Inclusion

Abstract

Only one positional isomer is obtained from the assembly of 21 small components. A triangular molecular panel with five coordination sites is assembled upon complexation with [PdII(en)] (en=ethylenediamine) into a unique M15L6 hexahedral coordination capsule (see X‐ray structure). The capsule can encapsulate/exchange organic guests reversibly through the clefts at the nonbinding sites of the capsule.

Mixed metal-organic nanocapsules

“…Fujita et al have blocked coordination sites on metal centers to great effect to generate a novel series of metal-organic structures with desirable topologies [35][36][37]. For example, these authors have synthesized a close-shelled nanocapsule based on six 1,3,5-tris(3,5-pyrimidyl)benzene molecules and 18 Pd 2+ metal ions.…”

“…5A). Molecules such as CBr 4 , CH 2 Br 2 , and CHCl 3 subsequently enter and exit the framework interior [36]. These authors also demonstrated that a similar strategy involving different solvents could provide other structures.…”

“…(A) A metal-organic cage with induced designer pores by ligand alteration[36]. (B) M4L8 and M3L6 structures formed from the same components in the presence of different solvents[37].…”

Metallo-supramolecular capsules

“…In the broad topic of this section, transition metals are often used for templating, and significant advances in large superstructures or clusters have been made by Fujita and coworkers [12][13][14][15][16][17][18], Stang and co-workers [19,20], Raymond and co-workers [21][22][23][24][25][26][27] and Ward and co-workers [28][29][30][31][32][33][34][35][36]. Fujita has reacted pyridyl or pyrimidyl functionalised planar or near planar ligands (that are typically triangular) with cis-protected palladium in order to synthesise a substantial series of metalorganic cages [12][13][14][15][16][17][18].…”

“…Fujita has reacted pyridyl or pyrimidyl functionalised planar or near planar ligands (that are typically triangular) with cis-protected palladium in order to synthesise a substantial series of metalorganic cages [12][13][14][15][16][17][18]. By developing the principles in ligand design, clefts were introduced to hexahedral assemblies, allowing form reversible guest inclusion [14]. Most impressively, further design principles involving naked palladium centres have used V-shaped ligands to afford finite spherical coordination networks that are based on cuboctahedral geometry, that have a diameter of around 3 nm, and that have openings that are ∼1-1.5Å wide (Fig.…”