Zirconium metal organic cages:From phosphate selective sensing to derivate forming

Luminescent metal organic cages(MOCs)have attracted great interest as a unique class of sensing substrates.In this work,intrinsically fluorescent Zr-MOCs were successfully used as fluorescent probes for the sensitive and selective detection of phosphate anions in water and real samples.When the ligand and Zr ion clusters form a cage,the intrinsic fluorescence of the ligand was tuned from high to weak emission due to the ligand-to-metal charge transfer(LMCT)effect,and this weakened fluorescence can be restored by the addition of phosphate.The degree of fluorescence enhancement is positively correlated with the added phosphate concentration,and the efficacy of this strategy is demonstrated by a linear phosphate detection range of 5–500µmol/L and a detection limit of 1.06µmol/L.We discuss the interaction between phosphate and Zr in scattering spectrum and MS,respectively.In comparison to phosphate adsorption on Zr-metal organic frameworks(MOFs),where phosphate connects different numbers of cages,both blocking the LMCT effect and causing the cages to aggregate.We also found that the phosphate displaces the ligand from the cage when the phosphate concentration is further expanded,resulting in the formation of new derivatives.This derivative was shown to be useful as a Lewis acid catalyst and as a rare earth ion adsorbent.

Planet-satellite cage hybrids:covalent organic cages encircling metal organic cage

As a rising type of precisely molecular nanoobjects,porous molecular cages,including covalent organic cages(COCs) and metal organic cages(MOCs),have attracted much more attention.It is fascinating to construct well-defined cage hybrids combining COCs and MOCs to further rich their types,properties,and applications.However,it is a big challenge due to the isotropy of the porous molecular cages.In this article,an anisotropic COC ligand based on aryl ether bonds and bearing one isophthalate moiety has been designed and synthesized.Then planet-satellite cage hybrids(PSCHs),MOC@COCs,have been constructed through the coordination of the anisotropic COC ligand and copper ions with or without the help of extra dicarboxylic ligands in an almost quantitative manner for the first time.Three PSCHs with one different topological MOC(heteroleptic bipolar,distorted cuboctahedral or homoleptic cuboctahedral) as the planet and different numbers of COCs(6,12 or 24) as satellites are obtained.The structural and thermal properties of these PSCHs have also been studied.The obtained PSCHs exhibit discrete,uniform and stable structures,good solubility and strong film-forming property.

Homochiral metalated tetraphenylethylene-based organic cages: Unusual chiral and luminescent behavior depending on thermodynamic and kinetic aggregation

Chirality and luminescence are important for both chemistry and biology,which are highly influenced by aggregation.In this work,a pair of metalated tetraphenylethylene(TPE)-based organic cage enantiomers are reported,which fea-ture a quadrangular prismatic cage structure.These homochiral cages exhibit concentration-dependent chiral behaviors alongside a propensity for thermodynamic aggregation.Aggregation caused quench effect is found for these cages accom-panying the increasing of the concentrations.When a poor solvent is added to produce a kinetical aggregation,the aggregation-annihilation circular dichroism and aggregation-induced emission behaviors are observed for these enantiomeric cages.By comparing these observations with the photophysical behaviors of a pair of structurally similar organic molecular enantiomers,the unique photophysical proper-ties observed are intricately linked to the metal-integrated TPE-functionalized cage structures.