pinecone/core-2020-05-10-deduplication huggingface dataset:
Complexation and Electronic Communication between\ud
Corannulene-Based Buckybowls and a Curved Truxene-TTF Donor

Abstract: The association behavior of an electron-donating, bowl-shaped, truxene-based tetrathiafulvalene (truxTTF) with  two corannulene-based fullerene fragments, C32H12 and C38H14, is investigated in several solvents. Formation of 1:1 complexes is followed by absorption titrations and complemented by density functional theory (DFT) calculations. The binding constants are in the range logKa=2.9–3.5. DFT calculations reveal that the most stable arrangement is the conformation in which the 1,3-dithiole ring of truxTTF is placed inside the concave cavity of the corannulene derivative. This arrangement is confirmed experimentally by NMR measurements, and implies that a combination of p–p and CH–p interactions is the driving force for association. Timedependent DFT calculations reproduce the experimental UV/Vis titrations and provide a detailed understanding of the spectral changes observed. Femtosecond transient absorption studies reveal the processes occurring after photoexcitation of either C32H12 or C38H14 and their supramolecular associates with truxTTF. In the case of truxTTF·C38H14, photoexcitation yields the charge-separated state truxTTFC +·C38H14C with a lifetime of approximately 160 ps
Platinum-Based Organometallic Folders for the Recognition of Electron-Deficient Aromatic Substrates

A series of platinum complexes with cis-oriented polyaromatic N-heterocyclic carbene ligands were prepared and characterized. The relative disposition of the polyaromatic ligands about the metal cause these compounds to behave as metallofolders, featuring a cavity defined by the void space between the polyaromatic functionalities. The complexes were used as receptors of organic molecules, whereby selective affinity was displayed for electron-deficient aromatic substrates, such as 1,2,4,5-tetracyanobenzene (TCNB), 2,4,7-trinitro-9-fluorenone (TNFLU), and 1,4,5,8-naphtalenetetracarboxylic dianhydride (NTCDA). The binding affinities of two of the metallofolders with these substrates were determined by means of 1H NMR titrations. Electrospray mass spectrometry (ESI-MS) was also used to assess the affinities. The molecular structure of one of the platinum folders was determined in the presence of TCNB, showing the clear interaction between this guest molecule and the folder formed by the two mutually cis-oriented polyaromatic ligands. This work demonstrates how the presence of the mutually cis-oriented polyaromatic ligands may be a very useful tool for the preparation of metal-based receptors
What a difference a methyl group makes - the selectivity of monoamine oxidase B towards histamine and N-methylhistamine

Monoamine oxidase (MAO) enzymes catalyze the degradation of a very broad range of biogenic and dietary amines including many neurotransmitters in the brain, whose imbalance is extensively linked with the biochemical pathology of various neurological disorders. Although sharing around 70% sequence identity, both MAO A and B isoforms differ in substrate affinities and inhibitor sensitivities. Inhibitors that act on MAO A are used to treat depression, due to their ability to raise serotonin concentrations, while MAO B inhibitors decrease dopamine degradation and improve motor control in patients with Parkinson disease. Despite this functional importance, the contributions affecting MAO selectivity are poorly understood. Here we used a combination of MD simulations, MM–PBSA binding free energy evaluations, and QM cluster calculations to address the unexpected, yet challenging MAO B selectivity for N-methylhistamine (NMH) over histamine (HIS), differing only in a single methyl group distant from the reactive ethylamino centre. We show that a dominant selectivity contribution is offered by a lower activation free energy for NMH by 2.6 kcal mol–1, in excellent agreement with the experimental ΔΔG‡ EXP = 1.4 kcal mol–1, together with a more favourable reaction exergonicity and active site binding. This study also confirms the hydrophobic nature of the MAO B active site and underlines the important role of Ile199, Leu171 and Leu328 in properly orienting substrates for the reaction
13C NMR spectroscopy of N-heterocyclic carbenes can selectively probe σ donation in gold(I) complexes

The Dewar-Chatt-Duncanson (DCD) model provides a successful theoretical framework to describe the nature of the chemical bond in transition-metal compounds and is especially useful in structural chemistry and catalysis. However, how to actually measure its constituents (substrate- to-metal donation and metal-to-substrate back-donation) is yet uncertain. Recently, we demonstrated that the DCD components can be neatly disentangled and the pi back-donation component put in strict correlation with some experimental observables. In the present work we make a further crucial step forward, showing that, in a large set of charged and neutral N-heterocyclic carbene complexes of gold(I), a specific component of the NMR chemical shift tensor of the carbenic carbon provides a selective measure of the sigma donation. This work opens the possibility of 1) to characterize unambiguously the electronic structure of a metal fragment (LAu(In+/0 in this case) by actually measuring its sigma-withdrawing ability, 2) to quickly establish a comparative trend for the ligand trans effect, and 3) to achieve a more rigorous control of the ligand electronic effect, which is a key aspect for the design of new catalysts and metal complexes
Continuous one-step synthesis of porous M-XF6-based metal-organic and hydrogen-bonded frameworks

Metal‐organic frameworks (MOFs) built up from connecting M‐XF₆ pillars through N‐donor ligands are among the most attractive adsorbents and separating agents for CO₂ and hydrocarbons today. The continuous, one‐step spray‐drying synthesis of several members of this isoreticular MOF family varying the anionic pillar (XF₆=[SiF₆]²⁻ and [TiF₆]²⁻), the N‐donor organic ligand (pyrazine and 4,4′‐bipyridine) and the metal ion (M=Co, Cu and Zn) is demonstrated here. This synthetic method allows them to be obtained in the form of spherical superstructures assembled from nanosized crystals. As confirmed by CO₂ and N₂ sorption studies, most of the M‐XF₆‐based MOFs synthesised through spray‐drying can be considered “ready‐to‐use” sorbents as they do not need additional purification and time consuming solvent exchange steps to show comparable porosity and sorption properties with the bulk/single‐crystal analogues. Stability tests of nanosized M‐SiF₆‐based MOFs confirm their low stability in most solvents, including water and DMF, highlighting the importance of protecting them once synthesised. Finally, for the first time it was shown that the spray‐drying method can also be used to assemble hydrogen‐bonded open networks, as evidenced by the synthesis of MPM‐1‐TIFSIX
The structure of linkers affects the DNA binding properties of tethered dinuclear ruthenium (II) metallo-intercalator

With the long-term aim of enhancing the binding properties of dinuclear RuII-based DNA light-switch complexes, a series of eight structurally related mono- and dinuclear systems are reported in which the linker of the bridging ligand has been modulated.These tethered systems have been designed to explore issues of steric demand at the binding site and the thermodynamic cost of entropy loss upon binding. An analysis of detailed spectroscopic and isothermal titration calorimetry (ITC) studies on the new complexes reveal that one of the linkers produces a dinuclear systems that binds to duplex DNA with an affinity (Kb > 107 M-1) that is higher than its corresponding monometallic complex and is the highest affinity for a non-threading bis-intercalating metal complex. These studies confirm that The tether has a major effect on the binding properties of dinuclear complexes containing intercalating units and establishes key design rules for the construction of dinuclear complexes with enhanced DNA binding characteristics
Double sequential encrypted targeting sequence: A new concept for bone cancer treatment

The selective transportation of therapeutic agents to tumoral cells is usually achieved by their conjugation with targeting moieties able to recognize these cells. Unfortunately, simple and static targeting systems usually show selectivity lacks. Herein, double sequential encrypted targeting system is proposed as stimuliresponsive targeting analogue for selectivity enhancement. The system is able to recognize diseased bone tissue in first place, and once there, a hidden secondary targeting group is activated by the presence of an enzyme overproduced in the malignant tissue (cathepsin K), triggering the recognition of diseased cells. Transporting the cell targeting agent in a hidden conformation which contains a high selective tissular primary targeting, could avoid not only its binding to similar cell receptors but also the apparition of the binding-site barrier effect, which can enhance the penetration of the therapeutic agent within the affected zone. This strategy could be applied not only to conjugate drugs but also to drug loaded nanocarriers in order to improve the efficiency for bone cancer treatments
Bis-Picolinamide ruthenium (III) dihalide complexes: dichloride to diiodide exchange generates single trans isomers with high potency and cancer cell selectivity

YesA library of new bis-picolinamide ruthenium(III) dihalide complexes of the type RuX2L2 (X = Cl or I and L = picolinamide) have been synthesised and characterised. They exhibit different picolinamide ligand binding modes, whereby one ligand is bound (N,N) and the other bound (N,O). Structural studies reveal a mixture of cis and trans isomers for the RuCl2L2 complexes but upon a halide exchange reaction to RuI2L2, only single trans isomers are present. High cytotoxic activity against human cancer cell lines was observed, with potencies for some complexes similar to or better than cisplatin. Conversion to RuI2L2 substantially increased activity towards cancer cell lines by >12-fold. The RuI2L2 complexes displayed potent activity against the A2780cis (cisplatin-resistant human ovarian cancer) cell line, with >4-fold higher potency than cisplatin. Equitoxic activity was observed against normoxic and hypoxic cancer cells, indicating the potential to eradicate both the hypoxic and aerobic fractions of solid tumours with similar efficiency. Selected complexes were also tested against non-cancer ARPE-19 cells. The RuI2L2 complexes are more potent than the RuCl2L2 analogues, and also more selective towards cancer cells with a selectivity factor >7-fold
Adamantylidene Addition to M3N@Ih-C80 (M=Sc, Lu) and Sc3N@D5h-C80: Synthesis and Crystallographic Characterization of the [5,6]-Open and [6,6]-Open Adducts

Additions of adamantylidene (Ad) to M3N@Ih‐C80 (M=Sc, Lu) and Sc3N@D5h‐C80 have been accomplished by photochemical reactions with 2‐adamantyl‐2,3′‐[3H]‐diazirine (1). In M3N@Ih‐C80, the addition led to rupture of the [6,6]‐ or [5,6]‐bonds of the Ih‐C80 cage, forming the [6,6]‐open fulleroid as the major isomer and the [5,6]‐open fulleroid as the minor isomer. In Sc3N@D5h‐C80, the addition also proceeded regioselectively to yield three major isomeric Ad mono‐adducts, despite the fact that there are nine types of C−C bonds in the D5h‐C80 cage. The molecular structures of the seven Ad mono‐adducts, including the positions of the encaged trimetallic nitride clusters, have been unambiguously determined through single‐crystal XRD analyses. Furthermore, results have shown that stepwise addition of Ad to Lu3N@Ih‐C80 affords several Ad bis‐adducts, two of which have been isolated and characterized. The X‐ray structure of one bis‐adduct clearly revealed that the second Ad addition took place at a [6,6]‐bond close to an endohedral metal atom. Theoretical calculations have also been performed to rationalize the regioselectivity
Synthesis of 2-Aminofurans by Sequential [2+2] Cycloaddition-Nucleophilic Addition of 2-Propyn-1-ols with Tetracyanoethylene and Amine-Induced Transformation into 6-Aminopentafulvenes

Synthesis of 2-aminofuran derivatives with an azulene or N,N-dimethylanilino substituent was established by the formal [2+2] cycloaddition-retroelectrocyclization of 3-(1-azulenyl or N,N-dimethylanilino)-2-propyn-1-ols with tetracyanoethylene, followed by intramolecular nucleophilic addition to the initially formed tetracyanobutadiene moiety of the internal hydroxyl group that come from 2-propyn-1-ol. The reaction proceeds under mild conditions with short reaction period. The products of the reaction are readily available through a simple purification procedure. 2-Aminofuran derivatives obtained by this reaction could be converted into 6-aminofulvene derivatives upon reaction with various amines. The structures of 2-aminofuran and 6-aminopentafulvene with a N,N-dimethylanilino substituent were confirmed by single-crystal X-ray structural analysis
Multimetallic and mixed environment iridium(III) complexes : a modular approach to luminescence tuning using a host platform

We thank the EPSRC for support (EP/M02105X/1) and for studentship (VEP, DTG award 1238852) and University of St Andrews for studentship (DRM).Mononuclear and trinuclear bis-cyclometalled Ir(III)complexes of the host ligands tris(4-[4’-methyl-2,2’-bipyridyl]methyl)cyclotriguaiacylene (L1) and tris(4-(4’-methyl-2,2’-bipyridyl)carboxy)cyclotriguaiacylene (L2) have been prepared. Complexes [{Ir(ppy)2}3(L1)](PF6)3 1.1, [{Ir(ppy)2}(L1)](PF6)31.2,[{Ir(ppy)2}3(L2)](PF6)3 2.1 and [{Ir(ppy)2}(L2)](PF6)3 2.2 (where ppy =phenylpyridinato) showed distinct photophysical properties according to L-ligand with L1 complexes comparatively blue-shifted in solution, with longer lifetimes and higher quantum yields. The mixed bis-cyclometallated Ir(III) complexes [{Ir(ppy)2}{Ir(dFppy)2}2(L1)](PF6)3 1.3,, [{Ir(ppy)2}{Ir(dFppy)2}2(L2)](PF6)3 2.3,[{Ir(ppy)2}2{Ir(dFppy)2}(L1)](PF6)3 1.4 and[{Ir(ppy)2}2{Ir(dFppy)2}(L2)](PF6)3 2.4 (where dFppy = 2,4-difluorophenylpyrinato) were also synthesised. Steady-state and time-resolved spectroscopy along with electrochemical investigation show that Ir(C^N)2 chromophores within these mixed Ir-environment species behave as isolated centres with no energy transfer or electronic communication between them.Publisher PDFPeer reviewe
Simultaneous triple imaging with two PARASHIFT probes : encoding anatomical, pH and temperature information using magnetic resonance shift imaging.

The chemical shift of paramagnetically shifted resonances in lanthanide(III) complexes encodes information about temperature and has also been made to report pH in parallel, through introduction of a single phosphonate group adjacent to the reporter tert-butyl resonance. The enhanced sensitivity of this new probe has allowed the simultaneous triple imaging of the water signal and the shifted tert-butyl signals of thulium and dysprosium complexes of a common ligand, separated by over 160 ppm. In parallel spectral imaging experiments, the temperature and pH dependence of the frequency of the Tm and Dy signals has been deconvoluted, allowing the pH and temperature in the liver, kidney and bladder to be measured
The Impact of Heteromultivalency in Lectin Recognition and Glycosidase Inhibition: An Integrated Mechanistic Study

The vision of multivalency as a strategy limited to achieve affinity enhancements between a protein receptor and its putative sugar ligand (glycotope) has proven too simplistic. On the one hand, binding of a glycotope in a dense glycocalix-like construct to a lectin partner has been shown to be sensitive to the presence of a third sugar entity (heterocluster effect). On the other hand, several carbohydrate processing enzymes (glycosidases and glycosyltransferases) have been found to be also responsive to multivalent presentations of binding partners (multivalent enzyme inhibition), a phenomenon first discovered for iminosugar-type inhibitory species (inhitopes) and recently demonstrated for multivalent carbohydrate constructs. By assessing a series of homo- and heteroclusters combining α-d-glucopyranosyl-related glycotopes and inhitopes, it was shown that multivalency and heteromultivalency govern both kinds of events, allowing for activation, deactivation or enhancement of specific recognition phenomena towards a spectrum of lectin and glycosidase partners in a multimodal manner. This unified scenario originates from the ability of (hetero)multivalent architectures to trigger glycosidase binding modes that are reminiscent of those harnessed by lectins, which should be considered when profiling the biological activity of multivalent architectures.Ministerio de Economía y Competitividad. Grant Numbers: SAF2016-76083-R, CTQ2015-64425-C2-1-RConsejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía. Grant Number: FQM2012-1467European Regional Development Fund
Responsive, water-soluble europium(III) luminescent probes.

The design principles, mechanism of action and performance of europium(III) complexes that serve as strongly emissive and responsive molecular probes in water are critically discussed. Examples of systems designed to assess pH, selected metal ions and anions, including chiral species, as well as selected small molecules and biopolymers are considered, and prospects evaluated for improved performance in more complex biological media such as in bio-fluids and within living cells. Modulation of the emission spectral form, lifetime and degree of circular polarisation can be used to quantify the spectral response and permit calibration
Mild, aqueous α-arylation of ketones : towards new diversification tools for halogenated metabolites and drug molecules

The authors thank the European Research Council (FP7/2007-2013/ERC grant agreement no 614779 to RJMG) and (FP7 2009-2014/ERC agreement no 227817 to SPN) for generous funding.The palladium-catalyzed aqueous α-arylation of ketones was developed and tested for a large variety of reaction partners. These mild conditions enabled the coupling of aryl/ alkyl-ketones with N-protected halotryptophans, heterocyclic haloarenes, and challenging base-sensitive compounds. The synthetic potential of this new methodology for the diversification of complex bioactive molecules was exemplified by derivatising prochlorperazine. The methodology is mild, aqueous and flexible, representing a means of functionalizing a wide range of halo-aromatics and therefore has the potential to be extended to complex molecule diversification.PostprintPeer reviewe
Homochiral self-sorted and emissive IrIII metallo-cryptophanes

We thank the EPSRC (DTG award 1238852, EP/K039202/1, EP/M02105X/1, EP/J001325/1), Leverhulme Trust (RPG-2014-148), University of St Andrews, and the MEXT/JSPS Grants in Aid for Scientific Research (JP25102005 and JP25102001) for funding; Simon Barrett for assistance with NMR; Martin Huscroft for assistance with HPLC, and Stephen Boyer for elemental analysis measurements.The racemic ligands (±)-tris(isonicotinoyl)-cyclotriguaiacylene (L1), or (±)-tris(4-pyridyl-methyl)-cyclotriguaiacylene (L2) assemblewith racemic (Λ, Δ)- [Ir(ppy)2(MeCN)2]+, in which ppy = 2-phenylpyridinato to form [{Ir(ppy)2}3(L)2]3+ metallo-cryptophane cages. The crystal structure of [{Ir(ppy)2}3(L1)2]∙3BF4 has MM-ΛΛΛ nd PP-ΔΔΔ isomers, and homochiral self-sorting occurs in solution, a processaccelerated by a chiral guest. Self-recognition between L1 and L2 within cagesdoes not occur, and cages show very slow ligand-exchange. Both cages are phosphorescent,with [{Ir(ppy)2}3(L2)2]3+ havingenhanced and blue-shifted emission when compared with [{Ir(ppy)2}3(L1)2]3+ .PostprintPeer reviewe
The synthesis and evaluation of fluoro-, trifluoromethyl, and iodomuscimols as GABA agonists

MAFAM acknowledges the Ministry of Education of Malaysia and Universiti Teknologi MARA for a scholarship. MC acknowledges the funding support of the Australian National Health and Medical Research Council (APP1081733).Halogenated analogues of the neurotoxic alkaloid muscimol were prepared with fluorine, iodine or trifluoromethyl at the 4 position of the isoxazole ring system. These compounds were investigated as agonists for GABAA receptors. Only the C-4 fluorine containing analogue proved to be an active compound in these assays. The fluoro analogue was less active than muscimol, however it showed differential activity between synaptic (α1β2γ2) and extrasynaptic (α4β2γ) GABAA receptors, having a similar potency to the neurotransmitter GABA for the extrasynaptic (α4β2γ) receptor.PostprintPostprintPeer reviewe
Exceptionally Long-Lived Photodriven Multi-Electron Storage without Sacrificial Reagents

Photoexcitation of a molecular pentad in the presence of Sc3+ in de-aerated CH3CN leads to a quinone dianion that is stable on the millisecond timescale. Light-driven electron accumulation on the quinone unit is sensitized by two Ru(bpy)32+ complexes in an intramolecular process, which relies on covalently attached triarylamine donors rather than on sacrificial reagents. Lewis acid–Lewis base interactions between Sc3+ and quinone dianion are responsible for the exceptionally long lifetime of this photoproduct. Our study of photoinduced multi-electron transfer is relevant in the greater context of solar energy conversion
Equilibrium, kinetic and structural properties of gallium(III) and some divalent metal complexes formed with the new DATAm and DATA5m ligands.

The development of 68Ge/68Ga generators has made the positron-emitting 68Ga isotope widely accessible and raised interest in new chelate complexes of Ga3+. The hexadentate 1,4-di(acetate)-6-methyl[amino(methyl)acetate]perhydro-1,4-diazepane (DATAm) ligand and its bifunctional analogue, 1,4-di(acetate)-6-pentanoic acid[amino(methyl)acetate]perhydro-1,4-diazepane (DATA5m), rapidly form complexes with 68Ga in high radiochemical yield. The stability constants of DATAm and DATA5m complexes formed with Ga3+, Zn2+, Cu2+, Mn2+ and Ca2+ have been determined by using pH potentiometry, spectrophotometry (Cu2+) and 1H and 71Ga NMR spectroscopy (Ga3+). The stability constants of Ga(DATAm) and Ga(DATA5m) complexes are slightly higher than those of Ga(AAZTA). The species distribution calculations indicated the predominance of Ga(L)OH mixed-hydroxo complexes at physiological pH. The 1H and 71Ga NMR spectroscopy studies provided information about the coordinated functional groups of ligands and on the kinetics of exchange between the Ga(L) and Ga(L)OH complexes. The transmetalation reactions between the Ga(L) complexes and Cu2+ citrate (6<pH<8.5) occur through both spontaneous and OH−-assisted dissociation of the Ga(L)OH species. At pH 7.4 and 25 °C, the half-lives of the dissociation of Ga(DATAm), Ga(DATA5m) and Ga(AAZTA) were 11, 44 and 24 h, respectively. Similar half-lives have been obtained for the ligand-exchange reactions between the Ga(L)OH complexes and transferrin. The equilibrium and kinetic data indicate that the Ga(DATA5m) complex is a good 68Ga-based radiodiagnostic candidate
Thermally activated delayed fluorescence in Cu(I) complexes originating from restricted molecular vibrations.

The mechanism of thermally activated delayed fluorescence (TADF) in molecules in aggregated or condensed solid states has been rarely studied and is not well understood. Nevertheless, many applications of TADF emitters are strongly affected by their luminescence properties in the aggregated state. In this study, two new isomeric tetradentate Cu(I) complexes which simultaneously show aggregation induced emission (AIE) and TADF characteristics are reported for the first time. We provide direct evidence that effectively restricting the vibrations of individual molecules is a key requisite for TADF in these two Cu(I) complexes through in-depth photophysical measurements combined with kinetic methods, single crystal analysis and theoretical calculations. These findings should stimulate new molecular engineering endeavours in the design of AIE-TADF active materials with highly emissive aggregated states