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418 results on '"Probert, Michael"'

1. Bioactivity-driven fungal metabologenomics identifies antiproliferative stemphone analogs and their biosynthetic gene cluster

Author

Ayon, Navid J., Earp, Cody E., Gupta, Raveena, Butun, Fatma A., Clements, Ashley E., Lee, Alexa G., Dainko, David, Robey, Matthew T., Khin, Manead, Mardiana, Lina, Longcake, Alexandra, Rangel-Grimaldo, Manuel, Hall, Michael J., Probert, Michael R., Burdette, Joanna E., Keller, Nancy P., Raja, Huzefa A., Oberlies, Nicholas H., Kelleher, Neil L., and Caesar, Lindsay K.

Published
2024
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3. Discovery, isolation, heterologous expression and mode-of-action studies of the antibiotic polyketide tatiomicin from Amycolatopsis sp. DEM30355

Author

Kepplinger, Bernhard, Mardiana, Lina, Cowell, Joseph, Morton-Laing, Stephanie, Dashti, Yousef, Wills, Corinne, Marrs, Emma C. L., Perry, John D., Gray, Joe, Goodfellow, Michael, Errington, Jeff, Probert, Michael R., Clegg, William, Bogaerts, Jonathan, Herrebout, Wouter, Allenby, Nick E. E., and Hall, Michael J.

Published
2022
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4. Ferrielectricity in an Organic Ferroelectric

Author

Scott, James F., Morrison, Finlay D., Clulow, Rebecca, Lightfoot, Philip, Gherson, Aurora, Capelli, Sylvia C., Probert, Michael R., Sahoo, S., Young, James S., and Katiyar, Ram S.

Subjects
Condensed Matter - Materials Science
Abstract

We report ferrielectricity in a single-phase crystal, TSCC -- tris-sarcosine calcium chloride [(CH3NHCH2COOH)3CaCl2]. Ferrielectricity is well known in smectic liquid crystals but almost unknown in true crystalline solids. Pulvari reported it in 1960 in mixtures of ferroelectrics and antiferroelectrics, but only at high fields. TSCC exhibits a second-order displacive phase transition near Tc = 130 K that can be lowered to a Quantum Critical Point at zero Kelvin via Br- or I-substitution, and phases predicted to be antiferroelectric at high pressure and low temperatures. Unusually, the size of the primitive unit cell does not increase. We measure hysteresis loops and polarization below T = 64 K and clear Raman evidence for this transition, as well of another transition near 47-50 K. X-ray and neutron studies below Tc = 130K show there is an antiferroelectric displacement out of plane of two sarcosine groups; but these are antiparallel displacements are of different magnitude, leading to a bias voltage that grows with decreasing T. A monoclinic subgroup C2 may be possible at the lowest temperatures (T<64K or T<48K), but no direct evidence exists for a crystal class lower than orthorhombic., Comment: 21 pages; 8 figures; 25 references

Published
2016
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12. Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells

Author

Alkhudhayr, Eman A. A., primary, Sirbu, Dumitru, additional, Fsadni, Miriam, additional, Vella, Benjamin, additional, Muhammad, Bening T., additional, Waddell, Paul G., additional, Probert, Michael R., additional, Penfold, Thomas J., additional, Hallam, Toby, additional, Gibson, Elizabeth A., additional, and Docampo, Pablo, additional

Published
2023
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19. Towards a fuller understanding of selected molecular compounds

Author

Probert, Michael R.

Subjects
541.2242
Abstract

This work is separated into two distinct sections. The first section deals with the analysis by variable temperature single crystal X-ray diffraction of crystalline molecular materials with novel physical properties. The second section details the electron density analysis of selected crystalline compounds using high resolution, low temperature single crystal X-ray diffraction. Chapter 1 provides introduction to X-ray diffraction outlining the theory this work is based on. Chapter 2 introduces the molecular material studies based on materials containing the bis(ethylenedithio)-tetrathiaftilvalene molecule. The aim of these studies was to achieve a greater understanding of the materials and the changes they undergo when exposed to variations in temperature whilst in the crystalline state. These structural changes observed are very minor but have dramatic effects on the electrical properties of the materials studied. It became apparent that the only way to form a full understanding of these materials was to be able to 'see' the electronic configuration of the materials, not just their gross structure. The field of electron density analysis by X- ray diffraction is now a well documented area. Chapter 4 provides an introduction to the field of electron density analysis. Diffraction experiments were conducted on systems of different complexity to investigate this field and these results are reported in Chapter 5. No electron density analyses have been conducted on the molecular materials studied in Chapter 3 as yet, due to the lack of crystals of suitable quality. It was also noted that to fully categorise the nature of the physical changes occurring in these structures that a diffractometer capable of analysing these samples throughout the temperature range of their physical phenomena was needed. An outline for the development of such a diffractometer is detailed in Chapter 6, 'future works'.

Published
2005

20. High‐throughput nanoscale crystallization of dihydropyridine active pharmaceutical ingredients.

Author

Metherall, Jessica P., Corner, Philip A., McCabe, James F., Hall, Michael J., and Probert, Michael R.

Subjects
DIMETHYL sulfoxide, CRYSTALLIZATION, DIHYDROPYRIDINE, SOLVATION, CALCIUM antagonists, SMALL molecules, SINGLE crystals
Abstract

Single‐crystal X‐ray diffraction analysis of small molecule active pharmaceutical ingredients is a key technique in the confirmation of molecular connectivity, including absolute stereochemistry, as well as the solid‐state form. However, accessing single crystals suitable for X‐ray diffraction analysis of an active pharmaceutical ingredient can be experimentally laborious, especially considering the potential for multiple solid‐state forms (solvates, hydrates and polymorphs). In recent years, methods for the exploration of experimental crystallization space of small molecules have undergone a 'step‐change', resulting in new high‐throughput techniques becoming available. Here, the application of high‐throughput encapsulated nanodroplet crystallization to a series of six dihydropyridines, calcium channel blockers used in the treatment of hypertension related diseases, is described. This approach allowed 288 individual crystallization experiments to be performed in parallel on each molecule, resulting in rapid access to crystals and subsequent crystal structures for all six dihydropyridines, as well as revealing a new solvate polymorph of nifedipine (1,4‐dioxane solvate) and the first known solvate of nimodipine (DMSO solvate). This work further demonstrates the power of modern high‐throughput crystallization methods in the exploration of the solid‐state landscape of active pharmaceutical ingredients to facilitate crystal form discovery and structural analysis by single‐crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Conductivity in Thin Films of Transition Metal Coordination Complexes

Author

Spinelli, Giovanni, Morritt, George H., Pavone, Michele, Probert, Michael R., Waddel, Paul G., Edvinsson, Tomas, Munoz-Garcia, Ana Belen, Freitag, Marina, Spinelli, Giovanni, Morritt, George H., Pavone, Michele, Probert, Michael R., Waddel, Paul G., Edvinsson, Tomas, Munoz-Garcia, Ana Belen, and Freitag, Marina

Abstract

Two coordination complexes have been made by combining the dithiolene complexes [M(mnt)(2)](2-) (mnt = maleonitriledithiolate; M = Ni2+ or Cu2+) as anion, with the copper(II) coordination complex [Cu(Stetra)] (Stetra = 6,6 ' - bis(4,5-dihydrothiazol-2-yl)-2,2 ' -bipyri-dine) as cation. The variation of the metal centers leads to a dramatic change in the conductivity of the materials, with the M = Cu2+ variant (Cu-Cu) displaying semiconductor behavior with a conductivity of approximately 2.5 x 10(-8) S cm(-1), while the M = Ni2+ variant (Ni-Cu) displayed no observable conductivity. Computational studies found Cu-Cu enables a minimization of reorganization energy losses and, as a result, a lower barrier to the charge transfer process, resulting in the reported higher conductivity.

Published
2023
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28. Synthesis and structure of an acyclic dialkylstannylene

Author

Izod Keith, Wills Corinne, Probert Michael R., and Harrington Ross W.

Subjects
lithium, tin, x-ray, Chemistry, QD1-999
Abstract

The reaction between iPr2 PCl and one equivalent of MeMgBr, followed by one equivalent of BH3·SMe2, gives the phosphine-borane iPr2 P(BH3)Me (4). Treatment of 4 with nBuLi, followed by Me3 SiCl, gives the sterically demanding phosphine-borane {iPr2 P(BH3)}(Me3 Si)CH2 (5) in good yield. Metalation of 5 with nBuLi yields {iPr2 P(BH3)}(Me3 Si)CHLi (6), which was crystallised as the TMEDA adduct [{iPr2 P(BH3)}(Me3 Si)CH]Li(TMEDA) (6a) and characterised by X-ray crystallography [TMEDA = N,N,N′,N′-tetramethylethylenediamine]. The reaction between two equivalents of in situ-generated 6 and Cp2 Sn in toluene gives the dialkylstannylene [{iPr2 P(BH3)}(Me3 Si)CH]2 Sn (7), which was crystallised from methylcyclohexane/THF as the rac diastereomer. X-ray crystallography reveals that stabilisation of the Sn centre in 7 is afforded by two agostic-type B-H…Sn interactions, one from each BH3 group.

Published
2014
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33. Copper coordination polymers with selective hole conductivity

Author

Michaels, Hannes, Golomb, Matthias J., Kim, Byeong Jo, Edvinsson, Tomas, Cucinotta, Fabio, Waddell, Paul G., Probert, Michael R., Konezny, Steven J., Boschloo, Gerrit, Walsh, Aron, Freitag, Marina, Michaels, Hannes, Golomb, Matthias J., Kim, Byeong Jo, Edvinsson, Tomas, Cucinotta, Fabio, Waddell, Paul G., Probert, Michael R., Konezny, Steven J., Boschloo, Gerrit, Walsh, Aron, and Freitag, Marina

Abstract

Emerging technologies in solar energy will be critical in enabling worldwide society in overcoming the present energy challenges and reaching carbon net zero. Inefficient and unstable charge transport materials limit the current emerging energy conversion and storage technologies. Low-dimensional coordination polymers represent an alternative, unprecedented class of charge transport materials, comprised of molecular building blocks. Here, we provide a comprehensive study of mixed-valence coordination polymers from an analysis of the charge transport mechanism to their implementation as hole-conducting layers. Cu-II dithiocarbamate complexes afford morphology control of 1D polymer chains linked by (CuI2X2) copper halide rhombi. Concerted theoretical and experimental efforts identified the charge transport mechanism in the transition to band-like transport with a modeled effective hole mass of 6m(e). The iodide-bridged coordination polymer showed an excellent conductivity of 1 mS cm(-1) and a hole mobility of 5.8 10(-4) cm(2) (V s)(-1) at room temperature. Nanosecond selective hole injection into coordination polymer thin films was captured by nanosecond photoluminescence of halide perovskite films. Coordination polymers constitute a sustainable, tunable alternative to the current standard of heavily doped organic hole conductors.

Published
2022
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34. Near‐Infrared Circularly Polarised Luminescence from Helically Extended Chiral N,N,O,O‐Boron Chelated Dipyrromethenes

Author

Algoazy, Nawaf, primary, Clarke, Rebecca G., additional, Penfold, Thomas J., additional, Waddell, Paul G., additional, Probert, Michael R., additional, Aerts, Roy, additional, Herrebout, Wouter, additional, Stachelek, Patrycja, additional, Pal, Robert, additional, Hall, Michael J., additional, and Knight, Julian G., additional

Published
2022
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35. Discovery, Isolation, Heterologous Expression and Mode of Action Studies of the Antibiotic Polyketide Tatiomicin from Amycolatopsis sp. DEM30355

Author

Kepplinger, Bernhard, primary, Mardiana, Lina, additional, Cowell, Joseph, additional, Morton-Laing, Stephanie, additional, Wills, Corinne, additional, Dashti, Yousef, additional, Marrs, Emma, additional, Perry, John, additional, Grey, Joe, additional, Goodfellow, Michael, additional, Errington, Jeff, additional, Probert, Michael, additional, Clegg, Bill, additional, Bogaerts, Jonathan, additional, Herrebout, Wouter, additional, Allenby, Nick E. E., additional, and Hall, Michael, additional

Published
2022
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37. The Role of the Fused Ring in Bicyclic Triazolium Organocatalysts: Kinetic, X-ray, and DFT Insights

Author

Zhu, Jiayun, primary, Moreno, Inmaculada, additional, Quinn, Peter, additional, Yufit, Dmitry S., additional, Song, Lijuan, additional, Young, Claire M., additional, Duan, Zhuan, additional, Tyler, Andrew R., additional, Waddell, Paul G., additional, Hall, Michael J., additional, Probert, Michael R., additional, Smith, Andrew D., additional, and O’Donoghue, AnnMarie C., additional

Published
2022
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39. Copper coordination polymers with selective hole conductivity

Author

Michaels, Hannes, primary, Golomb, Matthias J., additional, Kim, Byeong Jo, additional, Edvinsson, Tomas, additional, Cucinotta, Fabio, additional, Waddell, Paul G., additional, Probert, Michael R., additional, Konezny, Steven J., additional, Boschloo, Gerrit, additional, Walsh, Aron, additional, and Freitag, Marina, additional

Published
2022
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40. Derisking the Polymorph Landscape: The Complex Polymorphism of Mexiletine Hydrochloride

Author

Andrews, Jessica L., primary, Nilsson Lill, Sten O., additional, Freitag-Pohl, Stefanie, additional, Apperley, David C., additional, Yufit, Dmitry S., additional, Batsanov, Andrei S., additional, Mulvee, Matthew T., additional, Edkins, Katharina, additional, McCabe, James F., additional, Berry, David J., additional, Probert, Michael R., additional, and Steed, Jonathan W., additional

Published
2021
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41. The structure of a pentachromium(II) extended metal atom chain at 3 K: Cotton's conjecture proven.

Author

Cornia, Andrea, Nicolini, Alessio, McMonagle, Charles J., and Probert, Michael R.

Subjects
LOGICAL prediction, ATOMS, CHEMICAL bond lengths, COTTON, LOW temperatures
Abstract

We provide definitive experimental proof that the archetypal string-like compound [Cr5(tpda)4(NCS)2] has alternating long and short Cr–Cr separations in the solid state, as conjectured by F. A. Cotton, rather than essentially equally spaced Cr atoms, as initially claimed (H2tpda = N2,N6-di(pyridin-2-yl)pyridine-2,6-diamine). Single-crystal X-ray data collected from 292 to 3 K revealed that the misinterpretation is caused by pseudo-merohedral twinning and that bond length alternation is enhanced at low temperature. [ABSTRACT FROM AUTHOR]

Published
2022
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42. Differentiable Formation of Chiroptical Lanthanide Heterometallic LnnLn'4‐n(L6) (n=0–4) Tetrahedra with C2‐Symmetrical Bis(tridentate) Ligands.

Author

Yim, King‐Him, Yeung, Chi‐Tung, Wong, Melody Yee‐Man, Probert, Michael R., and Law, Ga‐Lai

Subjects
RARE earth metals, LIGANDS (Chemistry), TETRAHEDRA, SUPRAMOLECULAR chemistry, CRYSTALLIZATION
Abstract

Construction of lanthanide heterometallic complex is important for engineering multifunction molecular containers. However, it remains a challenge because of the similar ionic radii of lanthanides. Herein we attempt to prepare chiral lanthanide heterometallic tetrahedra. Upon crystallization with a mixture of [Eu2L3] and [Ln2L3] (Ln=Gd, Tb and Dy) helicates, a mixture of heterometallic EunLn'4‐n(L6) (n=0–4) tetrahedra was prepared. Selective formation of heterometallic tetrahedron was observed as MS deconvolution results deviated from statistical results. The formation of heterometallic tetrahedron was found to be sensitive to ionic radii as well as the ratio of the two helicates used in the crystallization. [ABSTRACT FROM AUTHOR]

Published
2022
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44. Accurate H-atom parameters for the two polymorphs of L -histidine at 5, 105 and 295 K

Author

Novelli, Giulia, McMonagle, Charles J., Kleemiss, Florian, Probert, Michael, Puschmann, Horst, Grabowsky, Simon, Maynard-Casely, Helen E., McIntyre, Garry J., and Parsons, Simon

Subjects
540 Chemistry, 570 Life sciences, biology
Abstract

The crystal structure of the monoclinic polymorph of the primary amino acid l-histidine has been determined for the first time by single-crystal neutron diffraction, while that of the orthorhombic polymorph has been reinvestigated with an untwinned crystal, improving the experimental precision and accuracy. For each polymorph, neutron diffraction data were collected at 5, 105 and 295 K. Single-crystal X-ray diffraction experiments were also performed at the same temperatures. The two polymorphs, whose crystal packing is interpreted by intermolecular interaction energies calculated using the Pixel method, show differences in the energy and geometry of the hydrogen bond formed along the c direction. Taking advantage of the X-ray diffraction data collected at 5 K, the precision and accuracy of the new Hirshfeld atom refinement method implemented in NoSpherA2 were probed choosing various settings of the functionals and basis sets, together with the use of explicit clusters of molecules and enhanced rigid-body restraints for H atoms. Equivalent atomic coordinates and anisotropic displacement parameters were compared and found to agree well with those obtained from the corresponding neutron structural models.

Published
2021
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47. Spontaneous Decomposition of an Extraordinarily Twisted and Trans‐Bent Fully‐Phosphanyl‐Substituted Digermene to an Unusual GeI Cluster.

Author

Izod, Keith, Liu, Mo, Evans, Peter, Wills, Corinne, Dixon, Casey M., Waddell, Paul G., and Probert, Michael R.

Subjects
NUCLEAR magnetic resonance spectroscopy, MONOMERS, TIN
Abstract

Ditetrelenes R2E=ER2 (E=Si, Ge, Sn, Pb) substituted by multiple N/P/O/S‐donor groups are extremely rare due to their propensity to disaggregate into their tetrylene monomers R2E. We report the synthesis of the first fully phosphanyl‐substituted digermene {(Mes)2P}2Ge=Ge{P(Mes)2}2 (3, Mes=2,4,6‐Me3C6H2), which adopts a highly unusual structure in the solid state, that is both strongly trans‐bent and highly twisted. Variable‐temperature 31P{1H} NMR spectroscopy suggests that 3 persists in solution, but is subject to a dynamic equilibrium between two conformations, which have different geometries about the Ge=Ge bond (twisted/non‐twisted) due to a difference in the nature of their π‐stacking interactions. Compound 3 undergoes unprecedented, spontaneous decomposition in solution to give a unique GeI cluster {(Mes)2P}4Ge4⋅5 CyMe (7). [ABSTRACT FROM AUTHOR]

Published
2022
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48. CAPOW: a standalone program for the calculation of optimal weighting parameters for least-squares crystallographic refinements

Author

Johnson, Natalie T., Ott, Holger, and Probert, Michael R.

Subjects
charge density, weighting, multipolar refinement, Computer Programs
Abstract

A new standalone program to calculate optimized values for weighting parameters, CAPOW, is presented along with enhanced visualization tools for analysing statistical distributions of data., The rigorous analysis of crystallographic models, refined through the use of least-squares minimization, is founded on the expectation that the data provided have a normal distribution of residuals. Processed single-crystal diffraction data rarely exhibit this feature without a weighting scheme being applied. These schemes are designed to reflect the precision and accuracy of the measurement of observed reflection intensities. While many programs have the ability to calculate optimal parameters for applied weighting schemes, there are still programs that do not contain this functionality, particularly when moving beyond the spherical atom model. For this purpose, CAPOW (calculation and plotting of optimal weights), a new program for the calculation of optimal weighting parameters for a SHELXL weighting scheme, is presented and an example of its application in a multipole refinement is given.

Published
2018

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