Cation induced changes to the structure of cryptophane cages.

Here the monocation complexes of seven -cryptophanes are examined with high-resolution ion-mobility mass spectrometry. The relative size of the [cation + cryptophane] complexes were compared based on their measured mobilities and derived collisional cross sections. A paradoxical trend of structural contraction was observed for complexes of increasing cation size.

Elucidating the Mechanism of Efficient Eu(III) and Yb(III) Sensitisation from a Re(I) Tetrazolato Triangular Assembly.

The reaction of Re(CO)Br with deprotonated 1H-(5-(2,2':6',2''-terpyridine)pyrid-2-yl)tetrazole yields a triangular assembly formed by tricarbonyl Re(I) vertices. Photophysical measurements reveal blue-green emission with a maximum at 520 nm, 32 % quantum yield, and 2430 ns long-lived excited state decay lifetime in deaerated dichloromethane solution. Coordination of lanthanoid ions to the terpyridine units red-shifts the emission to 570 nm and also reveals efficient (90 %) and fast sensitisation of both Eu(III) and Yb(III) at room temperature, with a similar rate constant k on the order of 10 s.

Revolutions in Lipid Isomer Resolution: Application of Ultrahigh-Resolution Ion Mobility to Reveal Lipid Diversity.

Many families of lipid isomers remain unresolved by contemporary liquid chromatography-mass spectrometry approaches, leading to a significant underestimation of the structural diversity within the lipidome. While ion mobility coupled to mass spectrometry has provided an additional dimension of lipid isomer resolution, some isomers require a resolving power beyond the capabilities of conventional platforms. Here, we present the application of high-resolution traveling-wave ion mobility for the separation of lipid isomers that differ in (i) the location of a single carbon-carbon double bond, (ii) the stereochemistry of the double bond ( or ), or, for glycerolipids, (iii) the relative substitution of acyl chains on the glycerol backbone (-position).

Diastereomer Resolution of M L Coordination Cages by Ultra-High-Resolution Ion-Mobility Mass Spectrometry.

Coordination cages can be used for enantio- and regioselective catalysis and for the selective sensing and separation of isomeric guest molecules. Here, stereoisomers of a family of coordination cages are resolved using ultra-high-resolution cyclic ion-mobility mass spectrometry (cIM-MS). The observed ratio of diastereomers is dependent on both the metal ion and counter ion.

Synergistic or antagonistic antioxidant combinations - a case study exploring flavonoid-nitroxide hybrids.

Neurodegenerative diseases impose a considerable medical and public health burden on populations throughout the world. Oxidative stress, an imbalance in pro-oxidant/antioxidant homeostasis that leads to the generation of reactive oxygen species (ROS), has been implicated in the progression of a number of neurodegenerative diseases. The manipulation of ROS levels may represent a promising treatment option to slow down neurodegeneration, although adequate potency of treatments has not yet been achieved.

Exploring the Gas-Phase Formation and Chemical Reactivity of Highly Reduced M L Coordination Cages.

Coordination cages with well-defined cavities show great promise in the field of catalysis on account of their unique combination of molecular confinement effects and transition-metal redox chemistry. Here, three coordination cages are reduced from their native 16 oxidation state to the 2 state in the gas phase without observable structural degradation. Using this method, the reaction rate constants for each reduction step were determined, with no noticeable differences arising following either the incorporation of a C -fullerene guest or alteration of the cage chemical structure.

Sensitised lanthanide luminescence using a Ru polypyridyl functionalised dipicolinic acid chelate.

A visible light absorbing [RuII(tpy)2]2+-type chromophore appended with a dipicolinic acid LnIII chelator has been prepared and complexed with several differing lanthanide cations to form the corresponding heterobimetallic d-f assemblies. The subseqent solution speciation analysed by 1H NMR spectroscopy revealed an unexpected decrease in the LnIII chelate complex stability, in particular for the 1 : 3 complex, when compared to the parent dipicolinic acid. As a result, the desired Ln(ML)3 complexes could not be isolated, and the 1 : 1 LnIII-ML complexes were instead characterised and investigated using steady state absorption and emission spectroscopy.

A Self-Catalyzed Visible Light Driven Thiol Ligation.

We introduce a highly efficient ligation system based on a visible light-induced rearrangement affording a thiophenol which rapidly undergoes thiol-Michael additions. Unlike conventional light-triggered thiol-ene/yne systems, which rely on the use of photocaged bases/nucleophiles, (organo)-photo catalysts, or radical photoinitiators, our system provides a light-induced reaction in the absence of any additives. The ligation is self-catalyzed the pyridine mediated deprotonation of the photochemically generated thiophenol.

Comment on "Trimorphs of 4-bromophenyl 4-bromobenzoate. Elastic, brittle, plastic" by S. Saha and G. R. Desiraju, , 2018, , 6348.

A re-refinement of the published but chemically implausible, crystal structure of "Form III" of 4-bromophenyl 4-bromobenzoate shows that it is not a polymorph, but instead a co-crystal containing both 4-bromophenyl 4-bromobenzoate (≈25%) and likely 4-bromophenyl 4-nitrobenzoate (≈75%).

Supramolecular Modulation of Spin Crossover in an Fe(II) Dinuclear Triple Helicate.

A spin-crossover (SCO) active dinuclear Fe(II) triple helicate of the form [Fe] was combined with additional supramolecular components in order to manipulate the interhelical separation and steric congestion and to study the magneto-structural effects on the ensuing composite materials. A more separated array of SCO units produced more extensive spin-transitions, while a tightly arranged lattice environment stabilized the low-spin state. This study highlights the important interplay between crystal packing, intermolecualr interactions, and the magentic behavior of SCO materials.

Quantification of energy transfer in bimetallic Pt(ii)-Ln(iii) complexes featuring an N^C^N-cyclometallating ligand.

Cyclometallated Pt(ii) complexes with arylpolypyridyl ligands have impressive photophysical properties (high quantum yields, long lifetimes and tuneable emission) which can be readily tuned by modification of the organic ligand. Despite this, few examples of cyclometallated Pt(ii) complexes as sensitisers for Ln(iii) emission have been reported. Herein, we report the photophysical properties for a series of bimetallic complexes incorporating an N^C^N-coordinated Pt(ii) bearing an alkynyl terpyridine as a metalloligand for a Ln(iii) ion (where Ln = Nd, Gd, Er, Yb and Lu).

Elastically Flexible Crystals have Disparate Mechanisms of Molecular Movement Induced by Strain and Heat.

Elastically flexible crystals form an emerging class of materials that exhibit a range of notable properties. The mechanism of thermal expansion in flexible crystals of bis(acetylacetonato)copper(II) is compared with the mechanism of molecular motion induced by bending and it is demonstrated that the two mechanisms are distinct. Upon bending, individual molecules within the crystal structure reversibly rotate, while thermal expansion results predominantly in an increase in intermolecular separations with only minor changes to molecular orientation through rotation.

A three-dimensional cubic halogen-bonded network.

The rational, deliberate design of supramolecular architectures is of great importance for the discovery of complex materials. A three-dimensional cubic halogen-bonded network has been prepared by combination of an octahedral metal-containing halogen bond acceptor and a linear ditopic donor. This material displays α-Po pcu topology and is seven-fold interpenetrated.

Atomic resolution of structural changes in elastic crystals of copper(II) acetylacetonate.

Single crystals are typically brittle, inelastic materials. Such mechanical responses limit their use in practical applications, particularly in flexible electronics and optical devices. Here we describe single crystals of a well-known coordination compound-copper(II) acetylacetonate-that are flexible enough to be reversibly tied into a knot.