Heterotrimetallic Double Cavity Cages: Syntheses and Selective Guest Binding

Abstract

A strategy for the generation of heterotrimetallic double cavity (DC) cages [PdnPtmL4]6+ (DC1: n=1, m=2; and DC2: n=2, m=1) is reported. The DC cages were generated by combining an inert platinum(II) tetrapyridylaldehyde complex with a suitably substituted pyridylamine and PdII ions. 1H and DOSY nuclear magnetic resonance spectroscopy (NMR) and electrospray ionization mass spectrometry (ESIMS) data were consistent with the formation of the DC architectures. DC1 and DC2 were shown to interact with several different guest molecules. The structure of DC1, which features two identical cavities, binding two 2,6‐diaminoanthraquinone (DAQ) guest molecules was determined by single‐crystal X‐ray crystallography. In addition, DC1 was shown to bind two molecules of 5‐fluorouracil (5‐FU) in a statistical (non‐cooperative) manner. In contrast, DC2, which features two different cage cavities, was found to interact with two different guests, 5‐FU and cisplatin, selectively.

Neighboring Cage Participation for Assisted Construction of Self-Assembled Multicavity Conjoined Cages and Augmented Guest Binding

“…Mixed-metal Pd 2 Pt 1 L 4 -and Pd 1 Pt 2 L 4 -type cages were prepared by the Crowley group recently. 16 We considered a set of bis-monodentate (L a ), trismonodentate (L b ), and tetrakis-monodentate (L c ) ligands to prepare a series of conjoined cages, including the abovementioned low-symmetry Pd 3 L 4 cage. 13 Complexation of Pd(II) with the tetrakis-monodentate ligand L c generated a quadruple-cavity Pd 6 L 6 -type cage, i.e., the Pd 6 (L c ) 6 cage.…”

“…The Crowley group utilized a tetrakis-monodentate ligand to prepare a Pd 4 L 4 -type triple-cavity cage that can be considered as a linear conjoin of three Pd 2 L 4 units of almost identical sizes, the central cavity being different from peripheral. Mixed-metal Pd 2 Pt 1 L 4 - and Pd 1 Pt 2 L 4 -type cages were prepared by the Crowley group recently . We considered a set of bis-monodentate (L a ), tris-monodentate (L b ), and tetrakis-monodentate (L c ) ligands to prepare a series of conjoined cages, including the above-mentioned low-symmetry Pd 3 L 4 cage .…”

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

“…36,37 Heterometallic MOCs are attractive targets as a second type of metal center can bring about new reactivity and impart unique magnetic, 38 photophysical, 39 and host−guest properties. 40 The assembly of heterometallic MOCs, however, is challenging due to the propensity of multicomponent mixtures forming homometallic structures. To overcome this, several strategies have been developed, including the utilization of metallo-ligands, 41−45 metal-bound subcomponents, 46,47 heterotopic ligands with hard and soft donors (binding to different metals preferentially), 48,49 or pre-formed heterobimetallic metal clusters.…”