Hexanuclear Ln6L6 Complex Formation by using an Unsymmetric Ligand

Multinuclear, self‐assembled lanthanide complexes present clear opportunities as sensors and imaging agents. Despite the widely acknowledged potential of this class of supramolecule, synthetic and characterization challenges continue to limit systematic studies into their self‐assembly restricting the number and variety of lanthanide architectures reported relative to their transition metal counterparts. Here we present the first study evaluating the effect of ligand backbone symmetry on multinuclear lanthanide complex self‐assembly. Replacement of a symmetric ethylene linker with an unsymmetric amide at the centre of a homoditopic ligand governs formation of an unusual Ln6L6 complex with coordinatively unsaturated metal centres. The choice of triflate as a counterion, and the effect of ionic radii are shown to be critical for formation of the Ln6L6 complex. The atypical Ln6L6 architecture is characterized using a combination of mass spectrometry, luminescence, DOSY NMR and EPR spectroscopy measurements. Luminescence experiments support clear differences between comparable Eu6L6 and Eu2L3 complexes, with relatively short luminescent lifetimes and low quantum yields observed for the Eu6L6 structure indicative of non‐radiative decay processes. Synthesis of the Gd6L6analogue allows three distinct Gd···Gd distance measurements to be extracted using homo‐RIDME EPR experiments

Undervalued and ignored:Are humans poorly adapted to energy-dense foods?

In many species the capacity to accurately differentiate the energy density (kcal/g) of foods is critical because it greatly improves efficiency in foraging. In modern humans this ability remains intact and is expressed in a selective preference for types of fruit and vegetables that contain more calories. However, humans evolved consuming these low energy-dense foods (typically < 1.75 kcal/g) and it remains unclear whether they can also discriminate more energy-dense foods that now feature in modern Western diets. In two experiment participants (both N = 40) completed four tasks that assessed the ‘value’ of different sets of 22 foods that ranged in energy density (0.1 kcal/g–5.3 kcal/g and range 0.1 kcal/g to 6.2 kcal/g in Experiment 1 and 2, respectively). In Experiment 1 three measures (expected fullness, calorie estimation, and food choice), and in foods less than approximately 1.5 kcal/g (typically fruits and vegetables), the relationship between perceived value and energy density is linear. Above this, we observed clear compressive functions, indicating relative and progressive undervaluation of higher energy-dense foods. The fourth task (rated liking) failed to provide evidence for any relationship with energy density. In Experiment 2 the same pattern was replicated in measures of expected fullness, and in two different assessments of subjective calorie content. Consistent with the concept of ‘evolutionary discordance,’ this work indicates that modern human physiology is poorly adapted to evaluate foods that have a historically unusual (high) energy density. This has implications both for our understanding of how ‘modern’ energy-dense foods affect choice and energy intake, and for strategies aimed at removing calories from highly energy-rich foods

The Magnetic and Electronic Structural Properties of the S3 State of Nature’s Water Oxidising Complex: A Combined Study in ELDOR-Detected Nuclear Magnetic Resonance Spectral Simulation and Broken Symmetry Density Functional Theory

ELDOR-detected Nuclear Magnetic Resonance (EDNMR) spectral simulations combined with broken symmetry density functional theory (BS-DFT) calculations are used to obtain and to assign the 55Mn hyperfine coupling constants (hfcs) for modified forms of the water oxidising complex in the penultimate S3 state of the water oxidation cycle. The study shows that an open cubane form of the core Mn4CaO6 cluster is the dominant S = 3 species in all cases studied experimentally with no need to invoke a closed cubane intermediate possessing a distorted pentacoordinate Mn4 ion. EDNMR simulations found that both the experimental bandwidth and multi-nuclear transitions may alter relative EDNMR peak intensities, potentially leading to incorrect assignment of hfcs. The implications of these findings for the water oxidation mechanism are discussed

Experimental realisation of multi-qubit gates using electron paramagnetic resonance

Abstract Quantum information processing promises to revolutionise computing; quantum algorithms have been discovered that address common tasks significantly more efficiently than their classical counterparts. For a physical system to be a viable quantum computer it must be possible to initialise its quantum state, to realise a set of universal quantum logic gates, including at least one multi-qubit gate, and to make measurements of qubit states. Molecular Electron Spin Qubits (MESQs) have been proposed to fulfil these criteria, as their bottom-up synthesis should facilitate tuning properties as desired and the reproducible production of multi-MESQ structures. Here we explore how to perform a two-qubit entangling gate on a multi-MESQ system, and how to readout the state via quantum state tomography. We propose methods of accomplishing both procedures using multifrequency pulse Electron Paramagnetic Resonance (EPR) and apply them to a model MESQ structure consisting of two nitroxide spin centres. Our results confirm the methodological principles and shed light on the experimental hurdles which must be overcome to realise a demonstration of controlled entanglement on this system