Chemistry inside molecular containers in the gas phase

Abstract

Inner-phase chemical reactions of guest molecules encapsulated in a macromolecular cavity give fundamental insight into the relative stabilization of transition states by the surrounding walls of the host, thereby modelling the situation of substrates in enzymatic binding pockets. Although in solution several examples of inner-phase reactions are known, the use of cucurbiturils as macrocyclic hosts and bicyclic azoalkanes as guests has now enabled a systematic mass spectrometric investigation of inner-phase reactions in the gas phase, where typically the supply of thermal energy results in dissociation of the supramolecular host-guest assembly. The results reveal a sensitive interplay in which attractive and repulsive van der Waals interactions between the differently sized hosts and guests need to be balanced with a constrictive binding to allow thermally activated chemical reactions to compete with dissociation. The results are important for the understanding of supramolecular reactivity and have implications for catalysis.

Topological landscapes of porous organic cages

“…Organic molecular cages have been of increasing research interest in recent years, [9][10][11][12][13] although they have a longer history, including a range of cryptands, 14 carcerands, 15,16 and capsule-like molecules. Potential applications for these molecular hosts include encapsulation, 17 catalysis, 18 molecular separations of organic molecules 19,20 or gases, 21,22 molecular sensing, 23,24 molecular reaction vessels, or as porous liquids. 25 Whilst framework materials can be related to underlying extended network topologies, the equivalent topologies for molecular materials include, but are not limited to, polyhedra such as Platonic and Archimedean solids, see Fig.…”

Binary twinned-icosahedral [B21H18]− interacts with cyclodextrins as a precedent for its complexation with other organic motifs

“…The formation of these charged complexes was proven by means of electrospray ionization mass spectrometry (ESI-MS), which is a powerful tool to study the stoichiometry and interactions of supramolecular assemblies in the gas phase. [12][13][14][15][16] Postulated weak gasphase basicities (GB) of these dianions served as an alternative explanation for the stability of these gas-phase complexes.…”

Label-Free Fluorescent Determination of Sunset Yellow in Soft Drinks Based on an Indicator-Displacement Assay

“…The popularity of CB[ ] is ascribed to their novel properties in the formation of inclusion complexes with various guest molecules with high selectivity and high binding constant in aqueous solution [17][18][19][20][21]. In recent years, fluorescence enhancement approach with IDA principle based on CB[ ] host-guest complexation has been used extensively for the determination of pesticides [22,23], drugs [24], and other compounds [25].…”