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Instruments / Technical Area	Publication Details	Published
I19-Small Molecule Single Crystal Diffraction	Luminescent copper (i) complexes with bisphosphane and halogen-substituted 2,2′-bipyridine ligands Sarah Keller , Alessandro Prescimone , Henk Bolink , Michele Sessolo , Giulia Longo , Laura Martínez-Sarti , José M. Junquera-Hernández , Edwin C. Constable , Enrique Ortí , Catherine E. Housecroft Dalton Transactions 124 DOI: 10.1039/C8DT01338A Diamond Proposal Number(s): [12801] Show Abstract ▼ Abstract: Heteroleptic [Cu(P^P)(N^N)][PF6] complexes, where N^N is a halo-substituted 2,2′-bipyridine (bpy) and P^P is either bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) have been synthesized and investigated. To stabilize the tetrahedral geometry of the copper(I) complexes, the steric demands of the bpy ligands have been increased by introducing 6- or 6,6′-halo-substituents in 6,6′-dichloro-2,2′-bipyridine (6,6′-Cl2bpy), 6-bromo-2,2′-bipyridine (6-Brbpy) and 6,6′-dibromo-2,2′-bipyridine (6,6′-Br2bpy). The solid-state structures of [Cu(POP)(6,6′-Cl2bpy)][PF6], [Cu(xantphos)(6,6′-Cl2bpy)][PF6]·CH2Cl2, [Cu(POP)(6-Brbpy)][PF6] and [Cu(xantphos)(6-Brbpy)][PF6]·0.7Et2O obtained from single crystal X-ray diffraction are described including the pressure dependence of the structure of [Cu(POP)(6-Brbpy)][PF6]. The copper(I) complexes with either POP or xantphos and 6,6′-Cl2bpy, 6-Brbpy and 6,6′-Br2bpy are orange-to-red emitters in solution and yellow-to-orange emitters in the solid state, and their electrochemical and photophysical properties have been evaluated with the help of density functional theory (DFT) calculations. The emission properties are strongly influenced by the substitution pattern that largely affects the geometry of the emitting triplet state. [Cu(POP)(6,6′-Cl2bpy)][PF6] and [Cu(xantphos)(6,6′-Cl2bpy)][PF6] show photoluminescence quantum yields of 15 and 17%, respectively, in the solid state, and these compounds were tested as luminophores in light-emitting electrochemical cells (LECs). The devices exhibit orange electroluminescence and very short turn-on times (<5 to 12 s). Maximum luminance values of 121 and 259 cd m−2 for [Cu(POP)(6,6′-Cl2bpy)][PF6] and [Cu(xantphos)(6,6′-Cl2bpy)][PF6], respectively, were achieved at an average current density of 100 A m−2. External quantum efficiencies of 1.2% were recorded for both complexes.	May 2018
I19-Small Molecule Single Crystal Diffraction	Controlling second coordination sphere effects in luminescent ruthenium complexes by external pressure Andrea Pannwitz , Stéphanie Poirier , Nicolas Bélanger-Desmarais , Alessandro Prescimone , Oliver S. Wenger , Christian Reber Chemistry - A European Journal DOI: 10.1002/chem.201800703 Diamond Proposal Number(s): [16314] Show Abstract ▼ Abstract: Two luminescent heteroleptic Ru(II) complexes with a 2,2'‐biimidazole (biimH2) ligand form doubly hydrogen‐bonded salt bridges to 4‐sulfobenzoate anions in single crystals. The structure of one of these cation‐anion adducts shows that the biimH2 ligand is deprotonated. Its 3MLCT luminescence bands does not shift significantly under the influence of an external hydrostatic pressure, a behavior typical for these electronic transitions. In contrast, hydrostatic pressure on the other crystalline cation‐anion adduct induces a shift of proton density from the peripheral N‐H groups of biimH2 towards benzoate, leading to a pronounced red‐shift of the 3MLCT luminescence band. Such a significant and pressure‐tuneable influence from an interaction in the second coordination sphere is unprecedented in artificial small molecule‐based systems.	Apr 2018
I19-Small Molecule Single Crystal Diffraction	Copper(i) and silver(i) complexes of 9,9-dimethyl-4,5-bis(di-tert-butylphosphino)xanthene: photophysical properties and structural rigidity under pressure Sarah Keller , Alessandro Prescimone , Edwin C. Constable , Catherine E. Housecroft Photochemical & Photobiological Sciences 32 DOI: 10.1039/C7PP00432J Diamond Proposal Number(s): [15176] Show Abstract ▼ Abstract: The heteroleptic complexes [Cu(tBu-xantphos)(bpy)][PF6] and [Ag(tBu-xantphos)(bpy)][PF6], where tBu-xantphos = 9,9-dimethyl-4,5-bis(di-tert-butylphosphino)xanthene and bpy = 2,2′-bipyridine have been synthesized and their photophysical properties investigated. Single crystal X-ray diffraction studies of the compounds under ambient and increased pressure are presented; increase in pressure results in little structural perturbation. For the copper(I) complexes, the effects of changing the N^N ligand from bpy to 6-methyl-2,2′-bipyridine (6-Mebpy), 6-bromo-2,2′-bipyridine (6-Brbpy), and 4,4′-di(tert-butyl)-2,2′-bipyridine (4,4′-tBu2bpy) were also investigated. Emissions from the copper(I) complexes are weak, both in solution and the solid state and this is attributed to vibrational quenching effects of the tert-butyl substituents of the tBu-xantphos ligands.	Feb 2018
I19-Small Molecule Single Crystal Diffraction	Pressure induced enhancement of the magnetic ordering temperature in rhenium(IV) monomers Christopher H. Woodall , Gavin A. Craig , Alessandro Prescimone , Martin Misek , Joan Cano , Juan Faus , Michael R. Probert , Simon Parsons , Stephen Moggach , José Martínez-Lillo , Mark Murrie , Konstantin V. Kamenev , Euan K. Brechin Nature Communications 7 DOI: 10.1038/ncomms13870 Diamond Proposal Number(s): [11879] Open Access Show Abstract ▼ Abstract: Materials that demonstrate long-range magnetic order are synonymous with information storage and the electronics industry, with the phenomenon commonly associated with metals, metal alloys or metal oxides and sulfides. A lesser known family of magnetically ordered complexes are the monometallic compounds of highly anisotropic d-block transition metals; the ‘transformation’ from isolated zero-dimensional molecule to ordered, spin-canted, three-dimensional lattice being the result of through-space interactions arising from the combination of large magnetic anisotropy and spin-delocalization from metal to ligand which induces important intermolecular contacts. Here we report the effect of pressure on two such mononuclear rhenium(IV) compounds that exhibit long-range magnetic order under ambient conditions via a spin canting mechanism, with Tc controlled by the strength of the intermolecular interactions. As these are determined by intermolecular distance, ‘squeezing’ the molecules closer together generates remarkable enhancements in ordering temperatures, with a linear dependence of Tc with pressure.	Dec 2016
I19-Small Molecule Single Crystal Diffraction	Inter- versus intramolecular structural manipulation of a dichromium(II) pacman complex through pressure variation Charlotte J. Stevens , Alessandro Prescimone , Floriana Tuna , Eric J. L. Mcinnes , Simon Parsons , Carole A. Morrison , Polly L. Arnold , Jason B. Love Inorganic Chemistry 55, 214 - 220 DOI: 10.1021/acs.inorgchem.5b02151 Diamond Proposal Number(s): [9205] Show Abstract ▼ Abstract: The effect of pressure on the intranuclear M···M separation and intermolecular secondary interactions in the dinuclear chromium Pacman complex [Cr2(L)](C6H6) was evaluated because this compound contains both a short Cr···Cr separation and an exogenously bound molecule of benzene in the solid state. The electronic structure of [Cr2(L)] was determined by electron paramagnetic resonance spectroscopy, SQUID magnetometry, and density functional theory calculations and shows a diamagnetic ground state through antiferromagnetic exchange, with no evidence for a Cr−Cr bond. Analysis of the solid-state structures of [Cr2(L)](C6H6) at pressures varying from ambient to 3.0 GPa shows little deformation in the Cr···Cr separation, i.e., no Cr−Cr bond formation, but instead a significantly increased interaction between the exogenous arene and the chromium iminopyrrolide environment. It is therefore apparent from this analysis that [Cr2(L)] would be best exploited as a rigid chemical synthon, with pressure regulation being used to mediate the approach and secondary interactions of possible substrates.	Jan 2016
I19-Small Molecule Single Crystal Diffraction	Characterizing pressure-induced uranium C-H agostic bonds Polly L. Arnold , Alessandro Prescimone , Joy H. Farnaby , Stephen M. Mansell , Simon Parsons , Nikolas Kaltsoyannis Angewandte Chemie International Edition 54, 6735 - 6739 DOI: 10.1002/anie.201411250 PMID: 25882329 Diamond Proposal Number(s): [9205] Open Access Show Abstract ▼ Abstract: The diuranium(III) compound [UN′′2]2(μ-η6:η6-C6H6) (N′′=N(SiMe3)2) has been studied using variable, high-pressure single-crystal X-ray crystallography, and density functional theory . In this compound, the low-coordinate metal cations are coupled through π- and δ-symmetric arene overlap and show close metal[BOND]CH contacts with the flexible methyl CH groups of the sterically encumbered amido ligands. The metal–metal separation decreases with increasing pressure, but the most significant structural changes are to the close contacts between ligand CH bonds and the U centers. Although the interatomic distances are suggestive of agostic-type interactions between the U and ligand peripheral CH groups, QTAIM (quantum theory of atoms-in-molecules) computational analysis suggests that there is no such interaction at ambient pressure. However, QTAIM and NBO analyses indicate that the interaction becomes agostic at 3.2 GPa.	Jun 2015
I19-Small Molecule Single Crystal Diffraction	Pressure-driven orbital reorientations and coordination-sphere reconstructions in [CuF2(H2O)2(pyz)] Alessandro Prescimone , Chelsey Morien , David Allan , John A. Schlueter , Stan W. Tozer , Jamie L. Manson , Simon Parsons , Euan K. Brechin , Stephen Hill Angewandte Chemie International Edition 51 (30), 7490 - 7494 DOI: 10.1002/anie.201202367 PMID: 22644620 Show Abstract ▼ Abstract: Successive reorientations of the Jahn–Teller axes associated with the CuII ions accompany a series of pronounced structural transitions in the title compound, as is shown by X-ray crystallography and high-frequency EPR measurements. The second transition forces a dimerization involving two thirds of the CuII sites due to ejection of one of the water molecules from the coordination sphere.	Jul 2012
	[Mn-6] under pressure: A combined crystallographic and magnetic study Alessandro Prescimone , Constantinos J. Milios , Stephen Moggach , John Warren , Alistair Lennie , Javier Sanchez-Benitez , Konstantin Kamenev , Roland Bircher , Mark Murrie , Simon Parsons , Euan K. Brechin Angewandte Chemie International Edition 47 (15), 2828 - 2831 DOI: 10.1002/anie.200705819 PMID: 18324653 Show Abstract ▼ Abstract: High-pressure crystallography of an Mn6 single-molecule magnet reveals dramatic changes in the intramolecular geometry of the magnetic core (see picture; Mn purple, O red, N blue). These structural changes effect the magnetic properties of the molecule: the magnitude of the ferromagnetic exchange between the metals is decreased, and under extreme pressure switches to antiferromagnetic.	Mar 2008

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