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99 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	Solvent‐dependent growth and stabilization mechanisms of surfactant‐free colloidal Pt nanoparticles Jonathan Quinson , Sarah Neumann , Laura Kacenauskaite , Jan Bucher , Jacob J. K. Kirkensgaard , Søren B. Simonsen , Luise Theil Kuhn , Alessandro Zana , Tom Vosch , Mehtap Oezaslan , Sebastian Kunz , Matthias Arenz Chemistry – A European Journal 26, 9012 - 9023 DOI: 10.1002/chem.202001553 Diamond Proposal Number(s): [12746] Show Abstract ▼ Abstract: Understanding the formation of nanoparticles (NPs) is key to develop materials by sustainable routes. The Co4CatTM process is a new synthesis of precious metal NPs in alkaline mono‐alcohols well‐suited to develop active nanocatalysts. The synthesis is ‘facile’, surfactant‐free and performed under mild conditions like low temperature. The reducing properties of the solvent are here shown to strongly influence the formation of Pt NPs. Based on the in situ formation of CO adsorbed on the NP surface by solvent oxidation, a model is proposed that accounts for the different growth and stabilization mechanisms as well as re‐dispersion properties of the surfactant‐free NPs in different solvents. Using in situ and ex situ characterizations, it is established that in methanol, a slow nucleation with a limited NP growth is achieved. In ethanol, a fast nucleation followed by continuous and pronounced particle sintering occurs.	Jul 2020
I12-JEEP: Joint Engineering, Environmental and Processing	Mechanistic in situ and ex situ studies of phase transformations in molecular co‐crystals Alexander Clout , Asma Buanz , Yuying Pang , Wing-mei Tsui , Dongpeng Yan , Gary Parkinson , Timothy Prior , Dejan-kresimir Bucar , Simon Gaisford , Gareth Williams Chemistry – A European Journal DOI: 10.1002/chem.202002267 Diamond Proposal Number(s): [12735] Open Access Show Abstract ▼ Abstract: Co‐crystallisation is widely explored as a route to improve the physical properties of pharmaceutical active ingredients, but little is known about the fundamental mechanisms of the process. Here we apply a novel hyphenated differential scanning calorimetry ‐ X‐ray diffraction technique to mimic the commercial hot melt extrusion process, and explore the heat‐induced synthesis of four new co‐crystals containing isonicotinamide. These comprise a 1:1 co‐crystal with 4‐hydroxybenzoic acid, 2:1 and 1:2 systems with 4‐hydroxyphenylacetic acid and a 1:1 crystal with 3,4‐dihydroxyphenylactic acid. The formation of co‐crystals during heating is complex mechanistically. In addition to co‐crystallisation, conversions between polymorphs of the co‐former starting materials and co‐crystal products are also observed. A subsequent study exploring the use of inkjet printing and milling to generate co‐crystals revealed that the synthetic approach has a major effect on the co‐crystal species and polymorphs produced.	Jul 2020
I19-Small Molecule Single Crystal Diffraction	Homo‐ and heterodinuclear arene‐linked osmium(II) and ruthenium(II) organometallics: probing the impact of metal variation on reactivity and biological activity Christopher S. Wilson , Timothy J. Prior , Jordon Sandland , Huguette Savoie , Ross W. Boyle , Benjamin Murray Chemistry – A European Journal DOI: 10.1002/chem.202002052 Show Abstract ▼ Abstract: Dinuclear metallodrugs offer much potential in the development of novel anticancer chemotherapeutics as a result of the distinct interactions possible with biomacromolecular targets and the unique biological activity that can result. Here, we describe the development of isostructural homodinuclear Os(II)‐Os(II) and heterodinuclear Os(II)‐Ru(II) organometallic complexes formed from the linking of the arene ligands of [M(η6‐arene)(C2O4)(PTA)] (M = Os/Ru; PTA = 1,3,5‐triaza‐7‐phosphaadamantane) units. Together with the known Ru(II)‐Ru(II) analogue, a chromatin‐modifying agent, we probed the impact of variation of the metal ions on the structure, reactivity and biological activity of these complexes. The complexes have been structurally characterised by X‐ray diffraction experiments, their stability and reactivity examined using 1H and 31P NMR spectroscopy and biological activity assessed, alongside mononuclear analogues, through MTT assays and cell cycle analysis (HT‐29 cell line). Results revealed high antiproliferative activity in each case with cell cycle profiles of the dinuclear complexes found to be similar to that for untreated cells, and similar but distinct profiles for the mononuclear complexes. These results indicate these complexes impact on cell viability predominantly through a non‐DNA damaging mechanism of action. The new Os(II)‐Os(II and Os(II)‐Ru(II) complexes reported here are further examples of a family of compounds operating via mechanism(s) of action atypical of the majority of metallodrugs, and which have potential as tools in chromatin research.	Jun 2020
I19-Small Molecule Single Crystal Diffraction	Luminescent anion sensing by transition‐metal dipyridylbenzene complexes incorporated into acyclic, macrocyclic and interlocked hosts Richard C. Knighton , Sophie Dapin , Paul D. Beer Chemistry – A European Journal 26, 5288 - 5296 DOI: 10.1002/chem.202000661 Diamond Proposal Number(s): [1858] Show Abstract ▼ Abstract: A series of novel acyclic, macrocyclic and mechanically interlocked luminescent anion sensors have been prepared by incorporation of the isophthalamide motif into dipyridylbenzene to obtain cyclometallated complexes of platinum(II) and ruthenium(II). Both the acyclic and macrocyclic derivatives 7⋅Pt, 7⋅Ru⋅PF6, 10⋅Pt and 10⋅Ru⋅PF6 are effective sensors for a range of halides and oxoanions. The near‐infra red emitting ruthenium congeners exhibited an increased binding strength compared to platinum due to the cationic charge and thus additional electrostatic interactions. Intramolecular hydrogen‐bonding between the dipyridylbenzene ligand and the amide carbonyls increases the preorganisation of both acyclic and macrocyclic metal derivatives resulting in no discernible macrocyclic effect. Interlocked analogues were also prepared, and preliminary luminescent chloride anion spectrometric titrations with 12⋅Ru⋅(PF6)2 demonstrate a marked increase in halide binding affinity due to the complementary chloride binding pocket of the [2]rotaxane. 1H NMR binding titrations indicate the interlocked dicationic receptor is capable of chloride recognition even in competitive 30 % aqueous mixtures.	Apr 2020
I19-Small Molecule Single Crystal Diffraction	Organic cage dumbbells Rebecca L. Greenaway , Valentina Santolini , Filip T. Szczypiński , Michael J. Bennison , Marc A. Little , Andrew Marsh , Kim E. Jelfs , Andrew I. Cooper Chemistry – A European Journal 26, 3718 - 3722 DOI: 10.1002/chem.201905623 Diamond Proposal Number(s): [21726] Show Abstract ▼ Abstract: Molecular dumbbells with organic cage capping units were synthesised via a multi‐component imine condensation between a tri‐topic amine and di‐ and tetra‐topic aldehydes. This is an example of self‐sorting, which can be rationalised by computational modelling.	Mar 2020
I03-Macromolecular Crystallography I04-1-Macromolecular Crystallography (fixed wavelength) I04-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	Iron biomineral growth from the initial nucleation seed in L‐ferritin Silvia Ciambellotti , Cecilia Pozzi , Stefano Mangani , Paola Turano Chemistry – A European Journal DOI: 10.1002/chem.202000064 Diamond Proposal Number(s): [15832, 21741] Show Abstract ▼ Abstract: X‐ray structures of homopolymeric human L‐ferritin and horse spleen ferritin were solved by freezing protein crystals at different time intervals after exposure to a ferric salt and revealed the growth of an octa‐nuclear iron cluster on the inner surface of the protein cage with a key role played by some glutamate residues. An atomic resolution view of how the cluster formation develops starting from a (μ 3 ‐oxo)tris[(μ 2 ‐glutamato‐κO:κO′)](glutamato‐κO)(diaquo)triiron(III) seed is provided. The results support the idea that iron biomineralization in ferritin is a process initiating at the level of the protein surface, capable of contributing coordination bonds and electrostatic guidance.	Feb 2020
I19-Small Molecule Single Crystal Diffraction	One guest or two? A crystallographic and solution study of guest binding in a cubic coordination cage Christopher Taylor , Stephen Argent , Michael Ludden , Jerico Piper , Cristina Mozaceanu , Sarah Barnett , Michael Ward Chemistry - A European Journal DOI: 10.1002/chem.201905499 Diamond Proposal Number(s): [19876] Show Abstract ▼ Abstract: A crystallographic investigation of a series of host/guest complexes in which small‐molecule organic guests occupy the central cavity of an approximately cubic M 8 L 12 coordination cage has revealed some unexpected behaviour. Whilst some guests form 1:1 H•G complexes as we have seen before, an extensive family of bicyclic guests – including some substituted coumarins and various saturated analogues – form 1:2 H•G 2 complexes in the solid state, despite the fact that solution titrations are consistent with 1:1 complex formation, and the combined volume of the pair of guests significantly exceeds the Rebek 55±9% packing for optimal guest binding, with packing coefficients of up to 87%. Re‐examination of solution titration data for guest binding in two cases showed that, although conventional fluorescence titrations are consistent with 1:1 binding model, alternative forms of analysis – Job plot and an NMR titration – at higher concentrations do provide evidence for 1:2 H•G 2 complex formation. The observation of guests binding in pairs in some cases opens up new possibilities for altered reactivity of bound guests, and also highlights the recently‐articulated difficulties associated with determining stoichiometry of supramolecular complexes in solution.	Dec 2019
I19-Small Molecule Single Crystal Diffraction	Coordination cage catalysed hydrolysis of organophosphates: cavity or surface based? Christopher Taylor , Alexander Metherell , Stephen Argent , Fatma Ashour , Nicholas Williams , Michael Ward Chemistry – A European Journal DOI: 10.1002/chem.201904708 Diamond Proposal Number(s): [19876] Show Abstract ▼ Abstract: The hydrophobic central cavity of a water‐soluble M8L12 cubic coordination cage can accommodate a range of phospho‐diester and phospho‐triester guests such as the insecticide 'dichlorvos' (2,2‐dichlorovinyl dimethyl phosphate) and the chemical warfare agent analogue diisopropyl chlorophosphate. The accumulation of hydroxide ions around the cationic cage surface due to ion‐pairing in solution generates a high local pH around the cage, resulting in catalysed hydrolysis of the phospho‐triester guests. A series of control experiments unexpectedly demonstrates that – in marked contrast to previous cases – it is not necessary for the phospho‐triester substrates to be bound inside the cavity for catalysed hydrolysis to occur. This suggests that catalysis can occur on the exterior surface of the cage as well as the interior surface, with the exterior‐binding catalysis pathway dominating here because of the small binding constants for these phospho‐triester substrates in the cage cavity. These observations suggest that cationic but hydrophobic surfaces could act as quite general catalysts in water by bringing substrates into contact with the surface (via the hydrophobic effect) where there is also a high local concentration of anions (due to ion‐pairing / electrostatic effects).	Nov 2019
I19-Small Molecule Single Crystal Diffraction	A tris(3‐pyridyl)stannane as a building block for heterobimetallic coordination polymers and supramolecular cages Dominic Wright , Eric Yang , Alex J. Plajer , Álvaro García-romero , Andrew D. Bond , Tanya Ronson , Celedonio M. Álvarez , Raúl García-rodríguez , Annie L. Colebatch Chemistry – A European Journal DOI: 10.1002/chem.201903498 Diamond Proposal Number(s): [15768] Show Abstract ▼ Abstract: The systematic assembly of supramolecular arrangements is a persistent challenge in modern coordination chemistry, especially where further aspects of complexity are concerned, as in the case of large molecular mixed‐metal arrangements. One targeted approach to such heterometallic complexes is to engineer metal‐based donor ligands of the correct geometry to build 3‐D arrangements upon coordination to other metals. This simple idea has, however, only rarely been applied to main group metal‐based ligand systems. Here we show that the new, bench‐stable tris(3‐pyridyl)stannane ligand PhSn(3‐Py)3 (3‐Py = 3‐pyridyl) provides simple access to a range of heterometallic Sn(IV)/transition metal complexes, and that the presence of weakly coordinating counteranions can be used to build discrete molecular arrangements involving anion encapsulation. This work therefore provides a building strategy in this area, which parallels that of supramolecular transition metal chemistry.	Aug 2019
I19-Small Molecule Single Crystal Diffraction	Multiple‐porphyrin functionalized hexabenzocoronenes Norbert Jux , Max M. Martin , Dominik Lungerich , Frank Hampel , Jens Langer , Tanya K. Ronson Chemistry – A European Journal DOI: 10.1002/chem.201903113 Diamond Proposal Number(s): [11397] Open Access Show Abstract ▼ Abstract: Porphyrin‐hexabenzocoronene architectures serve as good model compounds to study light harvesting systems. Herein, the synthesis of porphyrin functionalized hexa‐peri‐hexa‐benzocoronenes (HBCs), in which one or more porphyrins are covalently linked to a central HBC core, is presented. Therefore, a series of hexaphenylbenzenes (HPBs) was prepared and reacted under oxidative Scholl conditions. The transformation to the respective HBC derivatives worked well with mono‐ and tri‐porphyrin substituted HPBs. However, if more porphyrins are attached to the HPB core, Scholl oxidations are hampered or completely suppressed. Hence, a change of the synthetic strategy was necessary to first pre‐forming the HBC core, followed by the introduction of the porphyrins. All products were fully characterized, including, if possible, single crystal XRD. UV/Vis absorption spectra of porphyrin‐HBCs showed, depending on the number of porphyrins as well as with respect to the substitution pattern, variations in their spectral features with strong distortions of the porphyrins’ B‐band.	Aug 2019

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