The ground- and excited-state properties of a series of photochromic barbiturate receptors (N,N‘-bis{6-ω-(anthracen-9-yloxy)alkanoylaminopyridin-2-yl}-5-t-butyl-isophthalamide, T n ), in which ...anthracene chromophores are tethered via (CH2) n (n = 1, 3−6) polymethylene linkers to the H-bond receptor moiety, are described. In these systems, the thermally reversible 4π + 4π photodimerization of the anthracenes yields macrocyclic receptors (T n C) that possess significantly reduced affinity toward barbital as compared to their acyclic counterparts. The length of the tether not only determines the overall binding ability of the cyclized receptor but also has a profound influence on the photochemical and photophysical properties of the anthracene chromophores. The reduced mobility experienced by the covalently bound anthracenes controls the reactivity of a fluorescent excimer that is proposed to be an intermediate in the photocyclization process.
A macrocyclic ring comprising multiple hydrogen-bonding sites as well as metal-chelating sites is shown to play the role of ligand in active templated, copper-catalysed 2rotaxane formation via ...Huisgen and Glaser reactions. The crystallographic structure and copper ion binding studies are provided for the free macrocycle, along with molecular modelling, barbital, N,N′-trimethyleneurea and copper (I) binding information for the new rotaxanes.
A fluorescent DNA probe containing an anthracene group attached via an anucleosidic linker can identify all four DNA bases at a single site as well as the epigenetic modification C/5-MeC via a ...hybridisation sensing assay.
The synthesis and characterisation of novel metal-modified DNA precursors for fuel cell catalyst development are described. Material precursors in the form of metal-DNA complexes were prepared ...through the reaction of DNA with cisplatin at various loadings and spectroscopically tested to confirm the platinum binding mode and the degree of complexation. The surface morphology of the DNA-metal material was analysed by Scanning Transmission Electron Microscopy (STEM), which revealed the extent of platinum nanocluster formation, with low metal loadings leading to observation of individual platinum atoms. Electrochemical measurements showed a greater electrocatalytic activity for the hydrogen evolution reaction (HER) with increased platinum loadings, shifting the half wave potential,
E
1/2
, away from the glassy carbon limit towards that of a bulk Pt electrode. This is explained further by Tafel plots, from which a change in the mechanism of the apparent rate limiting step for proton reduction from a Volmer to a Heyrovsky mechanism is postulated as the platinum loading increases.
A new role for the well-known cisplatin-DNA reaction is reported in the form of a method to generate a catalytic nanomaterial containing individually positioned platinum atoms.
The labelling of DNA oligonucleotides with signalling groups that give a unique response to duplex formation depending on the target sequence is a highly effective strategy in the design of DNA-based ...hybridisation sensors. A key challenge in the design of these so-called base discriminating probes (BDPs) is to understand how the local environment of the signalling group affects the sensing response. The work herein describes a comprehensive study involving a variety of photophysical techniques, NMR studies and molecular dynamics simulations, on anthracene-tagged oligonucleotide probes that can sense single base changes (point variants) in target DNA strands. A detailed analysis of the fluorescence sensing mechanism is provided, with a particular focus on rationalising the high dependence of this process on not only the linker stereochemistry but also the site of nucleobase variation within the target strand. The work highlights the various factors and techniques used to respectively underpin and rationalise the BDP approach to point variant sensing, which relies on different responses to duplex formation rather than different duplex binding strengths.
The ability to discriminate between epigenetic variants in DNA is a necessary tool if we are to increase our understanding of the roles that they play in various biological processes and medical ...conditions. Herein, it is demonstrated how a simple two-step fluorescent probe assay can be used to differentiate all three major epigenetic variants of cytosine at a single locus site in a target strand of DNA.
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Scaffold design, synthesis and application are relevant for biomedical research. For example, multivalent interactions, such as those between cell surface glycoproteins and lectins ...can influence the potency and duration of signalling. The spacing between carbohydrates on their native protein scaffold could be important. Herein, the coiled coil design principle is used to generate synthetic coiled coil type glycoproteins, where three lactose residues are grafted to the coil via N-linkages to asparagine. Molecular modelling indicates that the distance between the galactose anomeric carbon atoms on the neoglycoproteins is ∼30Å. The inclusion of lactose was accommodated in both the final heptad towards the N-terminus, or more centrally in the penultimate heptad. In either case, neither the helicity nor the assembly to the trimeric form was unduly altered by the presence of the disaccharide.
Rates of pyramidal motion in an aziridine are controlled by reversible trans to cis photoisomerisation of an azobenzene unit attached to the ring nitrogen atom. The dynamics of the inversion process ...and activation parameters are derived by variable temperature NMR, and are supported by ab initio calculations.
The dynamics of pyramidal nitrogen inversion can be controlled by reversible redox switching in trans-2,3-diphenylaziridines bearing a suitable 1,4-naphthaquinone substituent. In the reduced form, an ...intramolecular H-bond significantly raises the inversion barrier slowing this molecular motion by >50-fold. The experimental findings are further supported by DFT calculations.
Synthetic hydrogen-bonding receptors are described, which incorporate a central electroactive ferrocene moiety grafted with two adjacent bis(amido)pyridine motifs and an aliphatic tether (14 and 18 ...methylene units for 1 and 2, respectively) completing the macrocycle. The crystallographic structure, barbiturate guest-binding studies and electrochemical data are provided for the more strongly-binding macrocycle 2.
![[2]Rotaxanes comprising a m...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1061-0278/small "[2]Rotaxanes comprising a macrocylic Hamilton receptor obtained using active template synthesis: synthesis and guest complexation")
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