Stabilization of Lantern-Type Metal-Organic Cages (MOCs) by Protective Control of Ligand Exchange Rates.

Self-assembling systems in nature display remarkable complexity with assemblies of different sub-units to generate functional species. Synthetic analogues of such systems are a challenge, often requiring the ability to bias distributions that are under thermodynamic assembly control. Using lantern-type MOCs (metal-organic cages) as a prototypical self-assembling system, herein we explore the role that steric bulk plays in controlling the exchange rate of ligands in paddlewheel-based assemblies, and thus the stability of cages, in competitive self-assembling scenarios. The effective lifetime of the lantern-type MOCs varies over an order of magnitude depending on the steric bulk proximal to the metal nodes with lifetimes of the cages ranging from tens of minutes to several hours. The bulk of the coordinating solvents likewise reduces the rate of ligand exchange, and thus yields longer-lived species. Understanding this subtle effect has implications for controlling the stability of complex assemblies in competitive environments with implications for guest release and application.

A chiral binaphthyl-based coordination polymer as an enantioselective fluorescence sensor.

A fluorescent, chiral coordination polymer (CP) with a novel topology has been synthesised using a dipyridyl ligand derived from 1,1'-bi-2-naphthol (BINOL). Enantioselectivity ratios up to 2.61 were obtained in fluorescence sensing studies with chiral analytes.

Chiral Detection with Coordination Polymers.

Coordination polymers and metal-organic frameworks are prime candidates for general chemical sensing, but the use of these porous materials as chiral probes is still an emerging field. In the last decade, they have found application in a range of chiral analysis methods, including liquid- and gas-phase chromatography, circular dichroism spectroscopy, fluorescence sensing, and NMR spectroscopy. In this minireview, we examine recent works on coordination polymers as chiral sensors and their enantioselective host-guest chemistry, while highlighting their potential for application in different settings.

A new spin crossover FeII coordination environment in a two-fold interpenetrated 3-D Hofmann-type framework material.

A 3-D FeII Hofmann-type framework material has been prepared which contains a three-connecting pyridyl-donor ligand with amide functionality and [Au(CN)2]- metallo-ligands. The FeII sites display a rare FeII(py)3(N[triple bond, length as m-dash]C)3 coordination environment, which we show for the first time to be conducive to spin crossover (SCO).