Heterotrimetallic Double Cavity Cages: Syntheses and Selective Guest Binding

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 Pd-II ions. H-1 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.

Automated summary

A strategy for generating heterotrimetallic double cavity cages and their interactions with different guest molecules were reported. The structures of the cages and their selective binding behavior were studied through various spectroscopic techniques. The results provide insights into the design and synthesis of multifunctional host-guest systems.