Notes

Enhanced transport of ions by intonation floor properties from the nanochannel.
Metallothioneins (MTs) are a ubiquitous class of small metal-binding proteins involved in metal homeostasis and detoxification. While known for their high affinity for d10 metal ions, there is a surprising dearth of thermodynamic data on metals binding to MTs. In this study, Zn2+ and Cu+ binding to mammalian metallothionein-3 (MT-3) were quantified at pH 7.4 by isothermal titration calorimetry (ITC). Zn2+ binding was measured by chelation titrations of Zn7MT-3, while Cu+ binding was measured by Zn2+ displacement from Zn7MT-3 with competition from glutathione (GSH). Titrations in multiple buffers enabled a detailed analysis that yielded condition-independent values for the association constant (K) and the change in enthalpy (ΔH) and entropy (ΔS) for these metal ions binding to MT-3. Zn2+ was also chelated from the individual α and β domains of MT-3 to quantify the thermodynamics of inter-domain interactions in metal binding. Comparative titrations of Zn7MT-2 with Cu+ revealed that both MT isoforms have similar Cu+ affinities and binding thermodynamics, indicating that ΔH and ΔS are determined primarily by the conserved Cys residues. Inductively coupled plasma mass spectrometry (ICP-MS) analysis and low temperature luminescence measurements of Cu-replete samples showed that both proteins form two Cu4 +-thiolate clusters when Cu+ displaces Zn2+ under physiological conditions. Comparison of the Zn2+ and Cu+ binding thermodynamics reveal that enthalpically-favoured Cu+, which forms Cu4 +-thiolate clusters, displaces the entropically-favoured Zn2+. These results provide a detailed thermodynamic analysis of d10 metal binding to these thiolate-rich proteins and quantitative support for, as well as molecular insight into, the role that MT-3 plays in the neuronal chemistry of copper.Asymmetrically bridged aroyl-S,N-ketene acetals and aroyl-S,N-ketene acetal multichromophores can be readily synthesized in consecutive three-, four-, or five-component syntheses in good to excellent yields by several successive Suzuki-couplings of aroyl-S,N-ketene acetals and bis(boronic)acid esters. Different aroyl-S,N-ketene acetals as well as linker molecules yield a library of 23 multichromophores with substitution and linker pattern-tunable emission properties. This allows control of different communication pathways between the chromophores and of aggregation-induced emission (AIE) and energy transfer (ET) properties, providing elaborate aggregation-based fluorescence switches.For the first time site-specific doping of silver into a spherical Au25 nanocluster has been achieved in [Au19Ag6(MeOPhS)17(PPh3)6] (BF4)2 (Au19Ag6) through a dual-ligand coordination strategy. Single crystal X-ray structural analysis shows that the cluster has a distorted centered icosahedral Au@Au6Ag6 core of D 3 symmetry, in contrast to the I h Au@Au12 kernel in the well-known [Au25(SR)18]- (R = CH2CH2Ph). An interesting feature is the coexistence of [Au2(SPhOMe)3] dimeric staples and [P-Au-SPhOMe] semi-staples in the title cluster, due to the incorporation of PPh3. The observation of only one double-charged peak in ESI-TOF-MS confirms the ordered doping of silver atoms. Au19Ag6 is a 6e system showing a distinct absorption spectrum from [Au25(SR)18]-, that is, the HOMO-LUMO transition of Au19Ag6 is optically forbidden due to the P character of the superatomic frontier orbitals.More than four decades ago, a complex identified as the planar homoleptic lithium nickelate "Li3NiPh3(solv)3" was reported by Taube and co-workers. This and subsequent reports involving this complex have lain dormant since; however, the absence of an X-ray diffraction structure leaves questions as to the nature of the Ni-PhLi bonding and the coordination geometry at Ni. By systematically evaluating the reactivity of Ni(COD)2 with PhLi under different conditions, we have found that this classical molecule is instead a unique octanuclear complex, [Li3(solv)2Ph3Ni2(μ-η2η2-C6H4)] (5). This is supported by X-ray crystallography and solution-state NMR studies. A theoretical bonding analysis from NBO, QTAIM, and ELI perspectives reveals extreme back-bonding to the bridging C6H4 ligand resulting in dimetallabicyclobutane character, the lack of a Ni-Ni bond, and pronounced σ-bonding between the phenyl carbanions and nickel, including a weak σC-Li → sNi interaction with the C-Li bond acting as a σ-donor. Employing PhNa led to the isolation of [Na2(solv)3Ph2NiCOD]2 (7) and [Na2(solv)3Ph2(NaC8H11)Ni(COD)]2 (8), which lack the benzyne-derived ligand. These findings provide new insights into the synthesis, structure, bonding and reactivity of heterobimetallic nickelates, whose prevalence in organonickel chemistry and catalysis is likely greater than previously believed.Reversible conversion between excited-states plays an important role in many photophysical phenomena. Using 1-(pyren-2'-yl)-o-carborane as a model, we studied the photoinduced reversible charge-transfer (CT) process and the thermodynamic equilibrium between the locally-excited (LE) state and CT state, by combining steady state, time-resolved, and temperature-dependent fluorescence spectroscopy, fs- and ns-transient absorption, and DFT and LR-TDDFT calculations. Our results show that the energy gaps and energy barriers between the LE, CT, and a non-emissive 'mixed' state of 1-(pyren-2'-yl)-o-carborane are very small, and all three excited states are accessible at room temperature. The internal-conversion and reverse internal-conversion between LE and CT states are significantly faster than the radiative decay, and the two states have the same lifetimes and are in thermodynamic equilibrium.The development of microporosity in the liquid state is leading to an inherent change in the way we approach applications of functional porosity, potentially allowing access to new processes by exploiting the fluidity of these new materials. By engineering permanent porosity into a liquid, over the transient intermolecular porosity in all liquids, it is possible to design and form a porous liquid. Since the concept was proposed in 2007, and the first examples realised in 2015, the field has seen rapid advances among the types and numbers of porous liquids developed, our understanding of the structure and properties, as well as improvements in gas uptake and molecular separations. However, despite these recent advances, the field is still young, and with only a few applications reported to date, the potential that porous liquids have to transform the field of microporous materials remains largely untapped. In this review, we will explore the theory and conception of porous liquids and cover major advances in the area, key experimental characterisation techniques and computational approaches that have been employed to understand these systems, and summarise the investigated applications of porous liquids that have been presented to date. We also outline an emerging discovery workflow with recommendations for the characterisation required at each stage to both confirm permanent porosity and fully understand the physical properties of the porous liquid.Electron injection is demonstrated to trigger electrocatalytic chain reactions capable of releasing a solvent molecule and forming a redox active guest molecule. One-electron reduction of a hydroxy anthrone derivative (AQH-CH2CN) results in the formation of an anthraquinone radical anion (AQ˙-) and acetonitrile (CH3CN). The resulting fragment of AQ˙- exhibits high stability under mild reducing conditions, and it has enough reducing power to reduce the reactant of AQH-CH2CN. Hence, subsequent electron transfer from AQ˙- to AQH-CH2CN yields the secondary AQ˙- and CH3CN, while the initial AQ˙- is subsequently oxidized to AQ. Overall, the reactants of AQH-CH2CN are completely converted into AQ and CH3CN in sustainable electrocatalytic chain reactions. These electrocatalytic chain reactions are mild and sustainable, successfully achieving catalytic electron-triggered charge-transfer (CT) complex formation. Reactant AQH-CH2CN is non-planar, making it unsuitable for CT interaction with an electron donor host compound (UHAnt2) bearing parallel anthracene tweezers. However, conversion of AQH-CH2CN to planar electron acceptor AQ by the electrocatalytic chain reactions turns on CT interaction, generating a host CT complex with UHAnt2 (AQ ⊂ UHAnt2). Therefore, sustainable electrocatalytic chain reactions can control CT interactions using only a catalytic amount of electrons, ultimately affording a one-electron switch associated with catalytic electron-triggered turn-on molecular recognition.Although the selective synthesis of complicated supramolecular architectures has seen significant progress in recent years, the exploration of the properties of these complexes remains a fascinating challenge. Herein, a series of new supramolecular topologies, metalla[2]catenanes and Borromean ring assemblies, were constructed based on appropriate Cp*Rh building blocks and two rigid alkynyl pyridine ligands (L1, L2) via coordination-driven self-assembly. Interestingly, minor differences between the two rigid alkynyl pyridine ligands with/without organic substituents led to products with dramatically different topologies. GANT61 Careful structural analysis showed that π-π stacking interactions play a crucial role in stabilizing these [2]catenanes and Borromean ring assemblies, while also promoting nonradiative transitions and triggering photothermal conversion in both the solution and the solid states. These results were showcased through comparative studies of the NIR photothermal conversion efficiencies of the Borromean ring assemblies, [2]catenanes and metallarectangles, which exhibited a wide range of photothermal conversion efficiencies (12.64-72.21%). The influence of the different Cp*Rh building blocks on the NIR photothermal conversion efficiencies of their assemblies was investigated. Good photothermal conversion properties of the assemblies were also found in the solid state. This study provides a new strategy to construct valuable half-sandwich-based NIR photothermal conversion materials while also providing promising candidates for the further development of materials science.We report the crystal structure of a new polymorph of l-tyrosine (denoted the β polymorph), prepared by crystallization from the gas phase following vacuum sublimation. Structure determination was carried out by combined analysis of three-dimensional electron diffraction (3D-ED) data and powder X-ray diffraction (XRD) data. Specifically, 3D-ED data were required for reliable unit cell determination and space group assignment, with structure solution carried out independently from both 3D-ED data and powder XRD data, using the direct-space strategy for structure solution implemented using a genetic algorithm. Structure refinement was carried out both from powder XRD data, using the Rietveld profile refinement technique, and from 3D-ED data. The final refined structure was validated both by periodic DFT-D calculations, which confirm that the structure corresponds to an energy minimum on the energy landscape, and by the fact that the values of isotropic 13C NMR chemical shifts calculated for the crystal structure using DFT-D methodology are in good agreement with the experimental high-resolution solid-state 13C NMR spectrum.
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