Assembly of a Heterometallic Cu(II)-Pd(II) Cage by Post-assembly Metal Insertion

Abstract

Porous structures based on multi-metallic motifs are receiving growing interest, but their general preparation still remains a challenge. Here, we report the self-assembly and structure of a CuII metal–organic cage (MOC) that is functionalized with free bis­(pyrazolyl)­methane sites. The homometallic Cu4L4 cage is isolated as a water-stable crystalline solid, and its formation is dependent on metal–ligand stoichiometry and the pre-organization of the Cu2 paddlewheel. We show by X-ray diffraction and SEM–EDX that PdII chloride can be quantitatively inserted into the free chelating sites of the MOC to yield a [Cu4(L­(PdCl2))4] structure. Moreover, the solvent employed in the metalation dictates the solid-state isomerism of the heterometallic cagea further handle to control the MOC’s structural diversity and permanent porosity.

Heterometallic cages: synthesis and applications

“…Bloch and co-workers have very recently synthesized a new heterometallic paddle-wheel cage using the post assembly modification approach. 189 The ligand ( L28 ) was synthesized by a Suzuki coupling between bis(4-iodo-3,5-dimethyl-1 H -pyrazol-1-yl)methane and 3-carboxyphenylboronic acid. L28 was then reacted with one equivalent of Cu 2 (OAc) 4 in DMF, which resulted in the formation of the homometallic Cu paddlewheel cage (Scheme 25).…”

Increasing the stability of calixarene-capped porous cages through coordination sphere tuning

“…While recent investigations involving permanently porous cages have demonstrated their utility as a promising class of molecular adsorbents, [1][2][3][4] further optimizing the porosity, stability, and processability of porous coordination cages will be vital for realizing their full potential. [5][6][7] Given their discrete nature, they have unrivaled tunability where their external and internal spaces, 8 structural diversity, 9 and solubility convey added potential for synthesis, 10 purification, 11 and utilization. 12 Although optimization and tuning of the relatively weak intermolecular interactions that govern the solid-state packing and stability of these materials have perhaps been challenging for porosity optimization, it does endow them with an additional level of control for various applications.…”

Maximized axial helicity in a Pd2L4cage: inverse guest size-dependent compression and mesocate isomerism

“…into such cage architectures offers the prospect of multi-functionalisation through heteroleptic, heterometallic or other low-symmetry assembly approaches. [25][26][27][28][29][30][31][32][33][34] Moreover, structural motifs such as skewed geometry and double-cage interpenetration have been shown to give rise to phenomena such as shape recognition, allosteric binding and stimuli responsiveness. [35][36][37][38] The relationship between axial helicity and the guest binding properties of M 2 L 4 coordination cages is somewhat ill-dened.…”