Supramolecular Coordination Complexes as Optical Biosensors

In recent years, luminescent supramolecular coordination complexes (SCCs), including 2D-metallacycles and 3D-metallacages have been utilised for biomolecular analysis. Unlike small-molecular probes, the dimensions, size, shape, and flexibility of these complexes can easily be tuned by combining ligands designed with particular geometries, symmetries and denticity with metal ions with strong geometrical binding preferences. The well-defined cavities that result, in combination with the other non-covalent interactions that can be programmed into the ligand design, facilitate great selectivity towards guest binding. In this Review we will discuss the application of luminescent metallacycles and cages in the binding and detection of a wide range of biomolecules, such as carbohydrates, proteins, amino acids, and biogenic amines. We aim to explore the effect of the structural diversity of SCCs on the extent of biomolecular sensing, expressed in terms of sensitivity, selectivity and detection range

Metal-organic ion transport systems

The design of synthetic membrane transporters for ions is a rapidly growing field of research, motivated by the potential medicinal applications of novel systems. Metal-organic coordination complexes provide access to a wide range of geometries, structures and properties and their facile synthesis and tunability offer advantages in the design of ion transport systems. In this review, the application of metal-organic constructs as membrane-spanning channels and ion carriers are explored, and the roles of the metal coordination complexes within these functional assemblies are highlighted

Guest Encapsulation within Surface-Adsorbed Self-Assembled Cages

Coordination cages encapsulate a wide variety of guests in the solution state. This ability renders them useful for applications such as catalysis and the sequestration of precious materials. A simple and general method for the immobilization of coordination cages on alumina is reported. Cage loadings are quantified via adsorption isotherms and guest displacement assays demonstrate that the adsorbed cages retain the ability to encapsulate and separate guest and non-guest molecules. Finally, a system of two cages, adsorbed on to different regions of alumina, stabilizes and separates a pair of Diels-Alder reagents. The addition of a single competitive guest results in the controlled release of the reagents, thus triggering their reaction. This method of coordination cage immobilization on solid phases is envisaged to be applicable to the extensive library of reported cages, enabling new applications based upon selective solid-phase molecular encapsulation

An Area‐Specific, International Community‐Led Approach to Understanding and Addressing Equality, Diversity, and Inclusion Issues within Supramolecular Chemistry

Diversity, equality, and inclusion (DEI/EDI) are pressing issues in chemistry and the natural sciences. In this Essay we share how an area‐specific approach is “calling in” the community so that it can act to address EDI issues, and support those who are marginalised. Women In Supramolecular Chemistry (WISC) is an international network that aims to support equality, diversity, and inclusion within supramolecular chemistry. WISC has taken a field‐specific approach using qualitative research methods with scientists to identify the support that is needed and the problems the supramolecular community needs to address. Herein, we present survey data from the community which highlight the barriers that are faced by those who take career breaks for any reason, a common example is maternity leave, and the importance of mentoring to aid progression post‐PhD. In conclusion, we set out an interdisciplinary and creative approach to addressing EDI issues within supramolecular chemistry

Coordination cages as permanently porous ionic liquids

Porous materials are widely used in industry for applications that include chemical separations and gas scrubbing. These materials are typically porous solids, although the liquid state can be easier to manipulate in industrial settings. The idea of combining the size and shape selectivity of porous domains with the fluidity of liquids is a promising one and porous liquids composed of functionalized organic cages have recently attracted attention. Here we describe an ionic-liquid, porous, tetrahedral coordination cage. Complementing the gas binding observed in other porous liquids, this material also encapsulates non-gaseous guests—shape and size selectivity was observed for a series of isomeric alcohols. Three gaseous chlorofluorocarbon guests, trichlorofluoromethane, dichlorodifluoromethane and chlorotrifluoromethane, were also shown to be taken up by the liquid coordination cage with an affinity that increased with their size. We hope that these findings will lead to the synthesis of other porous liquids whose guest-uptake properties may be tailored to fulfil specific functions

Comparative structural and thermodynamic studies of fluoride and cyanide binding by PhBMes(2) and related triarylborane Lewis acids

Lewis acidic boranes containing the -BMes2 unit (Mes = 2,4,6-Me3C6H2) have been widely exploited in molecular sensors for the fluoride ion reflecting, at least in part, the stability to air and moisture of derivatives of the type ArBMes2. In the current study, the fluoride binding capabilities of the simplest such system, PhBMes2 (1), have been investigated by spectroscopic and crystallographic methods, with a view to experimentally determining the fundamental thermodynamic and structural parameters associated with this host/guest interaction. A binding constant, KF, of 8.9(1.9) × 104 M-1 in dichloromethane solution and a B-F bond length of 1.481(2) for the salt [nBu4N]+[PhMes 2BF]- have thus been elucidated and provide a baseline for the analysis of more complex systems. Competitive binding of the cyanide ion is implied by a similar binding constant, KCN, of 1.9(0.5) × 105 M-1; structurally, similar degrees of pyramidalization of the BC3 framework are observed on coordination of each anion {Σ(C-B-C) = 339.8, 340.1°for [nBu4N] +[PhMes2BF]- and [K(18-crown-6)] +[PhMes2BCN]-, respectively}. Linking of two ArBMes2 units via an alkyne spacer results in a 2,2′- bis(dimesitylboryl)tolan system, which is characterized by independent binding of two equivalents of the CN- anion, rather than cyanide chelation. © 2010 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique