1
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Barlow SR, Halcovitch NR, Evans NH. A pyridine- N-oxide catenane for cation recognition. Org Biomol Chem 2024; 22:3001-3008. [PMID: 38526411 DOI: 10.1039/d4ob00176a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
The rapid preparation of a pyridine-N-oxide containing [2]catenane is described. The [2]catenane was characterized by NMR spectroscopy, mass spectrometry and X-ray single crystal structure determination. 1H NMR titration experiments reveal the [2]catenane may be reversibly protonated, as well as an ability to bind lithium cations more strongly than sodium cations.
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Affiliation(s)
- Sean R Barlow
- Department of Chemistry, Lancaster University, Lancaster, LA1 4YB, UK.
| | | | - Nicholas H Evans
- Department of Chemistry, Lancaster University, Lancaster, LA1 4YB, UK.
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2
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Ekka A, Choudhury A, Samanta M, Deshmukh A, Halcovitch NR, Park IH, Medishetty R. Solid-State [2+2] Photoreaction of Isostructural Cd(II) Metal Complexes and Solid-State Fluorescence. Molecules 2024; 29:351. [PMID: 38257264 PMCID: PMC10820883 DOI: 10.3390/molecules29020351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/29/2023] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
A green method to synthesize cyclobutane derivatives has been developed over the past three decades in the form of solid-state [2+2] photochemical reactions. These solid-state reactions also play a major role in the structural transformation of hybrid materials. In this regard, crystal engineering has played a major role in designing photoreactive molecular systems. Here, we report three novel binuclear Cd(II) complexes with the molecular formula [Cd2(4spy)4L4], where 4spy = 4-styryl pyridine and L = p-toluate (1); 4-fluorobenzoate (2); and 3-fluorobenzoate (3). Although three different benzoates are used, all three complexes are isostructural, as corroborated through SCXRD experiments. Structural analysis also helped in identifying two potential photoreactions. These are both intra- and intermolecular in nature and are driven by the head-to-head (HH) and head-to-tail (HT) alignment of 4spy linkers within these metal complexes. 1H NMR spectroscopy studies showed evidence of a quantitative head-to-head photoreaction in all these three complexes, and SCXRD analysis of the recrystallization of the photoproducts also provided confirmation. TGA studies of these photoreactive complexes showed an increase in the thermal stability of the complexes due to the solid-state photoreaction. Photoluminescence studies of these complexes have been conducted, showing a blue shift in emission spectra across all three cases after the photoreaction.
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Affiliation(s)
- Akansha Ekka
- Department of Chemistry, Indian Institute of Technology Bhilai, Durg 491001, India (A.C.)
| | - Aditya Choudhury
- Department of Chemistry, Indian Institute of Technology Bhilai, Durg 491001, India (A.C.)
| | - Madhumita Samanta
- Department of Chemistry, Indian Institute of Technology Bhilai, Durg 491001, India (A.C.)
| | - Ayushi Deshmukh
- Department of Chemistry, Indian Institute of Technology Bhilai, Durg 491001, India (A.C.)
| | | | - In-Hyeok Park
- Graduate School of Analytical Science and Technology (GRAST), Chungnam National University, Daejeon 34134, Republic of Korea
| | - Raghavender Medishetty
- Department of Chemistry, Indian Institute of Technology Bhilai, Durg 491001, India (A.C.)
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3
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Beament B, Britton D, Malcomson T, Akien GR, Halcovitch NR, Coogan MP, Platel RH. Selective Transesterification to Control Copolymer Microstructure in the Ring-Opening Copolymerization of Lactide and ε-Caprolactone by Lanthanum Complexes. Inorg Chem 2024; 63:280-293. [PMID: 38126711 PMCID: PMC10777408 DOI: 10.1021/acs.inorgchem.3c03120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 12/05/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023]
Abstract
A series of novel lanthanum amido complexes, supported by ligands designed around the salan framework (salan = N,N'-bis(o-hydroxy, m-di-tert-butylbenzyl)-1,2-diaminoethane) were synthesized and fully characterized in the solid and solution states. The ligands incorporate benzyl or 2-pyridyl substituents at each tertiary amine center. The complexes were investigated as catalysts in the ring-opening homopolymerization of lactide (LA) and ε-caprolactone (ε-CL) and copolymerization of equimolar amounts of LA and ε-CL at ambient temperature. Solvent (THF or toluene) and the number of 2-pyridyl groups in the complex were found to influence the reactivity of the catalysts in copolymerization reactions. In all cases, complete conversion of LA to PLA was observed. The use of THF, a coordinating solvent, suppressed ε-CL polymerization, while the presence of one or more 2-pyridyl groups promoted ε-CL polymerization. Each copolymer gave a monomodal trace in gel permeation chromatography-size-exclusion chromatography (GPC-SEC) experiments, indicative of copolymer formation over homopolymerization. Copolymer microstructure was found to be dependent on catalyst structure and reaction solvent, ranging from blocky to close to alternating. Experiments revealed rapid conversion of LA in the initial stages of the reaction, followed by incorporation of ε-CL into the copolymer by either transesterification or propagation reactions. Significantly, the mode of transesterification (TI or TII) that occurs is determined by the structure of the metal complex and the reaction solvent, leading to the possibility of controlling copolymer microstructure through catalyst design.
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Affiliation(s)
- Bette Beament
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Daniel Britton
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Thomas Malcomson
- Department
of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Geoffrey R. Akien
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Nathan R. Halcovitch
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Michael P. Coogan
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Rachel H. Platel
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
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4
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Griffiths K, Greenfield JL, Halcovitch NR, Fuchter MJ, Griffin JM. Systematic Investigation into the Photoswitching and Thermal Properties of Arylazopyrazole-based MOF Host-Guest Complexes. Cryst Growth Des 2023; 23:7044-7052. [PMID: 37808902 PMCID: PMC10557064 DOI: 10.1021/acs.cgd.2c01384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 08/25/2023] [Indexed: 10/10/2023]
Abstract
A series of arylazopyrazole-loaded metal-organic frameworks were synthesized with the general formula Zn2(BDC)2(DABCO)(AAP)x (BDC = 1,4-benzenedicarboxylate; DABCO = 1,4-diazabicyclo-[2.2.2]octane; AAP = arylazopyrazole guest). The empty framework adopts a large pore tetragonal structure. Upon occlusion of the E-AAP guests, the frameworks contract to form narrow pore tetragonal structures. The extent of framework contraction is dependent on guest shapes and pendant groups and ranges between 1.5 and 5.8%. When irradiated with 365 nm light, the framework expands due to the photoisomerization of E-AAP to Z-AAP. The proportion of Z-isomer at the photostationary state varies between 19 and 57% for the AAP guests studied and appears to be limited by the framework which inhibits further isomerization once fully expanded. Interestingly, confinement within the framework significantly extends the thermal half-life of the Z-AAP isomers to a maximum of approximately 56 years. This finding provides scope for the design of photoresponsive host-guest complexes with high stability of the metastable isomer for long-duration information or energy storage applications.
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Affiliation(s)
- Kieran Griffiths
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, U.K.
| | - Jake L. Greenfield
- Molecular
Sciences Research Hub, Department of Chemistry, Imperial College London, London W12 0BZ, U.K.
- Center
for Nanosystems Chemistry (CNC), Institut
für Organische Chemie, Universität, Würzburg, Würzburg 97074, Germany
| | | | - Matthew J. Fuchter
- Molecular
Sciences Research Hub, Department of Chemistry, Imperial College London, London W12 0BZ, U.K.
| | - John M. Griffin
- Department
of Chemistry, Lancaster University, Lancaster LA1 4YB, U.K.
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5
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Lowe JP, Halcovitch NR, Coote SC. Preparation and Synthetic Applications of Phototropone. J Org Chem 2023. [PMID: 37341104 DOI: 10.1021/acs.joc.3c00590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
An optimized multigram-scale route to phototropone (bicyclo[3.2.0]hepta-2,6-dien-7-one) is reported via the 4-π-photocyclization of tropone complexed to Lewis acid. Phototropone is a highly versatile molecular building block, and its conversion into 18 novel derivatives using standard transformations is demonstrated, allowing access to a variety of rigid bicyclic scaffolds.
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Affiliation(s)
- Jack P Lowe
- Department of Chemistry, Lancaster University, Bailrigg, LA1 4YB, U.K
| | | | - Susannah C Coote
- Department of Chemistry, Lancaster University, Bailrigg, LA1 4YB, U.K
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6
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Ekka A, Kurakula U, Choudhury A, Mishra A, Faye A, Halcovitch NR, Medishetty R. Light-driven flagella-like motion of coordination compound single crystals. Chem Commun (Camb) 2023; 59:4384-4387. [PMID: 36946868 DOI: 10.1039/d3cc00333g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Single crystals of coordination complexes that show mechanical motion under the influence of external stimuli are of great interest due to their applications in photoactuators, sensors and probes. The solid-state [2+2] cycloaddition reaction has been one of the most prominent chemical reactions for photoresponsive materials in recent years. However, a relatively limited number of compounds have been reported, and most of these compounds have only shown destructive photosalient effects. Here, we report two photoreactive Zn(II) metal complexes with a thiophene-based photoreactive linker, 2tpy (4-(2-(thiophen-2-yl)vinyl)pyridine). In addition, under photoirradiation these complexes showed flagella-like bending, first towards and subsequently away from the excitation light source. This is the first report of metal-complexes and the solid-state [2+2] cycloaddition reaction that presents flagella-like motion in single crystals.
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Affiliation(s)
- Akansha Ekka
- Department of Chemistry, Indian Institute of Technology Bhilai, GEC Campus, Sejbahar, Raipur, 492015, Chhattisgarh, India.
| | - Uma Kurakula
- Department of Chemistry, Indian Institute of Technology Bhilai, GEC Campus, Sejbahar, Raipur, 492015, Chhattisgarh, India.
| | - Aditya Choudhury
- Department of Chemistry, Indian Institute of Technology Bhilai, GEC Campus, Sejbahar, Raipur, 492015, Chhattisgarh, India.
| | - Anshumika Mishra
- Department of Chemistry, Indian Institute of Technology Bhilai, GEC Campus, Sejbahar, Raipur, 492015, Chhattisgarh, India.
| | - Anshul Faye
- Department of Mechanical Engineering, Indian Institute of Technology Bhilai, GEC Campus, Sejbahar, Raipur, 492015, Chhattisgarh, India
| | - Nathan R Halcovitch
- Chemistry Department, Lancaster University, Faraday Building, Lancaster University, Lancaster, LA1 4YB, UK
| | - Raghavender Medishetty
- Department of Chemistry, Indian Institute of Technology Bhilai, GEC Campus, Sejbahar, Raipur, 492015, Chhattisgarh, India.
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7
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Samie M, Khan AF, Rahman SU, Iqbal H, Yameen MA, Chaudhry AA, Galeb HA, Halcovitch NR, Hardy JG. Drug/bioactive eluting chitosan composite foams for osteochondral tissue engineering. Int J Biol Macromol 2023; 229:561-574. [PMID: 36587649 DOI: 10.1016/j.ijbiomac.2022.12.293] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 12/19/2022] [Accepted: 12/25/2022] [Indexed: 12/30/2022]
Abstract
Joint defects associated with a variety of etiologies often extend deep into the subchondral bone leading to functional impairment and joint immobility, and it is a very challenging task to regenerate the bone-cartilage interface offering significant opportunities for biomaterial-based interventions to improve the quality of life of patients. Herein drug-/bioactive-loaded porous tissue scaffolds incorporating nano-hydroxyapatite (nHAp), chitosan (CS) and either hydroxypropyl methylcellulose (HPMC) or Bombyx mori silk fibroin (SF) are fabricated through freeze drying method as subchondral bone substitute. A combination of spectroscopy and microscopy (Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and X-ray fluorescence (XRF) were used to analyze the structure of the porous biomaterials. The compressive mechanical properties of these scaffolds are biomimetic of cancellous bone tissues and capable of releasing drugs/bioactives (exemplified with triamcinolone acetonide, TA, or transforming growth factor-β1, TGF-β1, respectively) over a period of days. Mouse preosteoblast MC3T3-E1 cells were observed to adhere and proliferate on the tissue scaffolds as confirmed by the cell attachment, live-dead assay and alamarBlue™ assay. Interestingly, RT-qPCR analysis showed that the TA downregulated inflammatory biomarkers and upregulated the bone-specific biomarkers, suggesting such tissue scaffolds have long-term potential for clinical application.
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Affiliation(s)
- Muhammad Samie
- Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, 54000, Pakistan; Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, 22060, Pakistan; Department of Chemistry, Lancaster University, Lancaster, Lancashire LA1 4YB, United Kingdom; Materials Science Institute, Lancaster University, Lancaster, Lancashire LA1 4YW, United Kingdom; Institute of Pharmaceutical Sciences, Khyber Medical University, Peshawar, Khyber Pakhtunkhwa 25100, Pakistan.
| | - Ather Farooq Khan
- Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, 54000, Pakistan
| | - Saeed Ur Rahman
- Institute of Basic Medical Sciences, Khyber Medical University, Peshawar, Khyber Pakhtunkhwa 25100, Pakistan
| | - Haffsah Iqbal
- Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, 54000, Pakistan
| | - Muhammad Arfat Yameen
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad Campus, 22060, Pakistan
| | - Aqif Anwar Chaudhry
- Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, 54000, Pakistan
| | - Hanaa A Galeb
- Department of Chemistry, Lancaster University, Lancaster, Lancashire LA1 4YB, United Kingdom; Department of Chemistry, Science and Arts College, Rabigh Campus, King Abdulaziz University, 21577 Jeddah, Saudi Arabia
| | - Nathan R Halcovitch
- Department of Chemistry, Lancaster University, Lancaster, Lancashire LA1 4YB, United Kingdom
| | - John G Hardy
- Department of Chemistry, Lancaster University, Lancaster, Lancashire LA1 4YB, United Kingdom; Materials Science Institute, Lancaster University, Lancaster, Lancashire LA1 4YW, United Kingdom.
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8
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Michalska WZ, Halcovitch NR, Coote SC. Synthesis of functionalized spirocyclic oxetanes through Paternò-Büchi reactions of cyclic ketones and maleic acid derivatives. Chem Commun (Camb) 2023; 59:784-787. [PMID: 36562323 DOI: 10.1039/d2cc06459f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A telescoped three-step sequence to functionalised spirocyclic oxetanes is reported, involving Paternò-Büchi reactions between maleic acid derivatives and cyclic ketones. p-Xylene suppresses the competing alkene dimerization that has plagued previous work, allowing access to 35 novel spirocyclic oxetanes that cannot be prepared using existing methodologies, and which represent versatile intermediates for further elaboration.
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Affiliation(s)
| | | | - Susannah C Coote
- Department of Chemistry, Lancaster University, Bailrigg, LA1 4YB, UK.
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9
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Haskew MJ, Nikman S, O'Sullivan CE, Galeb HA, Halcovitch NR, Hardy JG, Murphy ST. Mg/Zn metal‐air primary batteries using silk fibroin‐ionic liquid polymer electrolytes. Nano Select 2022. [DOI: 10.1002/nano.202200200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Mathew J. Haskew
- School of Engineering Lancaster University Bailrigg Lancaster UK
- Department of Chemistry Lancaster University Faraday Building Bailrigg Lancaster UK
| | - Shahin Nikman
- Department of Chemistry Lancaster University Faraday Building Bailrigg Lancaster UK
| | - Carys E. O'Sullivan
- Department of Chemistry Lancaster University Faraday Building Bailrigg Lancaster UK
| | - Hanaa A. Galeb
- Department of Chemistry Lancaster University Faraday Building Bailrigg Lancaster UK
- Department of Chemistry Science and Arts College, Rabigh Campus King Abdulaziz University Jeddah Saudi Arabia
| | - Nathan R. Halcovitch
- Department of Chemistry Lancaster University Faraday Building Bailrigg Lancaster UK
| | - John G. Hardy
- Department of Chemistry Lancaster University Faraday Building Bailrigg Lancaster UK
- Materials Science Institute Lancaster University Faraday Building, John Creed Avenue Bailrigg Lancaster UK
| | - Samuel T. Murphy
- School of Engineering Lancaster University Bailrigg Lancaster UK
- Materials Science Institute Lancaster University Faraday Building, John Creed Avenue Bailrigg Lancaster UK
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10
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Basson AJ, Halcovitch NR, McLaughlin MG. Unified Approach to Diverse Fused Fragments via Catalytic Dehydrative Cyclization. Chemistry 2022; 28:e202201107. [PMID: 35642626 PMCID: PMC9542485 DOI: 10.1002/chem.202201107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Indexed: 11/17/2022]
Abstract
A range of highly functionalized polycyclic fragments have been synthesized, employing a catalytic dehydrative cyclization. A range of nucleophiles are shown to be successful, with the reaction producing numerous high value motifs.
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Affiliation(s)
- Ashley J. Basson
- Department of Chemistry Lancaster University Bailrigg Lancaster LA1 4YB UK
| | | | - Mark G. McLaughlin
- Department of Chemistry Lancaster University Bailrigg Lancaster LA1 4YB UK
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11
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Whewell T, Seymour VR, Griffiths K, Halcovitch NR, Desai AV, Morris RE, Armstrong AR, Griffin JM. A structural investigation of organic battery anode materials by NMR crystallography. Magn Reson Chem 2022; 60:489-503. [PMID: 35023583 DOI: 10.1002/mrc.5249] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/05/2022] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Conjugated alkali metal dicarboxylates have recently received attention for applications as organic anode materials in lithium- and sodium-ion batteries. In order to understand and optimise these materials, it is important to be able to characterise both the long-range and local aspects of the crystal structure, which may change during battery cycling. Furthermore, some materials can display polymorphism or hydration behaviour. NMR crystallography, which combines long-range crystallographic information from diffraction with local information from solid-state NMR via interpretation aided by DFT calculations, is one such approach, but this has not yet been widely applied to conjugated dicarboxylates. In this work, we evaluate the application of NMR crystallography for a set of model lithium and sodium dicarboxylate salts. We investigate the effect of different DFT geometry optimisation strategies and find that the calculated NMR parameters are not systematically affected by the choice of optimisation method, although the inclusion of dispersion correction schemes is important to accurately reproduce the experimental unit cell parameters. We also observe hydration behaviour for two of the sodium salts and provide insight into the structure of an as-yet uncharacterised structure of sodium naphthalenedicarboxylate. This highlights the importance of sample preparation and characterisation for organic sodium-ion battery anode materials in particular.
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Affiliation(s)
- Tommy Whewell
- Department of Chemistry, Lancaster University, Lancaster, UK
| | - Valerie R Seymour
- Department of Chemistry, Lancaster University, Lancaster, UK
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
| | | | | | - Aamod V Desai
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
- EastChem School of Chemistry, University of St Andrews, St Andrews, UK
| | - Russell E Morris
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
- EastChem School of Chemistry, University of St Andrews, St Andrews, UK
| | - A Robert Armstrong
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
- EastChem School of Chemistry, University of St Andrews, St Andrews, UK
| | - John M Griffin
- Department of Chemistry, Lancaster University, Lancaster, UK
- The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, UK
- Materials Science Institute, Lancaster University, Lancaster, UK
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12
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Abstract
Crystalline binary mixtures of azobenzene and 4-methoxyazobenzene are reported and form photochemical phase change materials that possess working temperatures in the range of −58 °C to 31 °C.
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Affiliation(s)
- Kieran Griffiths
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, UK
| | | | - John M. Griffin
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, UK
- Materials Science Institute, Lancaster University, Lancaster, LA1 4YB, UK
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13
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Griffiths K, Halcovitch NR, Griffin JM. Efficient solid-state photoswitching of methoxyazobenzene in a metal–organic framework for thermal energy storage. Chem Sci 2022; 13:3014-3019. [PMID: 35382460 PMCID: PMC8905824 DOI: 10.1039/d2sc00632d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 02/15/2022] [Indexed: 01/01/2023] Open
Abstract
Efficient photoswitching in the solid-state remains rare, yet is highly desirable for the design of functional solid materials. In particular, for molecular solar thermal energy storage materials high conversion to the metastable isomer is crucial to achieve high energy density. Herein, we report that 4-methoxyazobenzene (MOAB) can be occluded into the pores of a metal–organic framework Zn2(BDC)2(DABCO), where BDC = 1,4-benzenedicarboxylate and DABCO = 1,4-diazabicyclo[2.2.2]octane. The occluded MOAB guest molecules show near-quantitative E → Z photoisomerization under irradiation with 365 nm light. The energy stored within the metastable Z-MOAB molecules can be retrieved as heat during thermally-driven relaxation to the ground-state E-isomer. The energy density of the composite is 101 J g−1 and the half-life of the Z-isomer is 6 days when stored in the dark at ambient temperature. 4-Methoxyazobenzene can be occluded into the pores of a MOF and show near-quantitative E → Z photoisomerization under irradiation with 365 nm light. The energy density of the composite is 101 J g−1 and the half-life of the Z-isomer is 6 days.![]()
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Affiliation(s)
- Kieran Griffiths
- Department of Chemistry, Lancaster University, Lancaster, LA14YB, UK
| | | | - John M. Griffin
- Department of Chemistry, Lancaster University, Lancaster, LA14YB, UK
- Materials Science Institute, Lancaster University, Lancaster, LA14YB, UK
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14
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Griffiths K, Halcovitch NR, Griffin JM. Effect of Transition Metal Substitution on the Flexibility and Thermal Properties of MOF-Based Solid-Solid Phase Change Materials. Inorg Chem 2021; 60:12950-12960. [PMID: 34492769 DOI: 10.1021/acs.inorgchem.1c01364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of azobenzene-loaded metal-organic frameworks were synthesized with the general formula M2(BDC)2(DABCO)(AB)x (M = Zn, Co, Ni, and Cu; BDC = 1,4-benzenedicarboxylate; DABCO = 1,4-diazabicyclo[2.2.2]octane; and AB = azobenzene), herein named M-1⊃ABx. Upon occlusion of AB, each framework undergoes guest-induced breathing, whereby the pores contract around the AB molecules forming a narrow-pore (np) framework. The loading level of the framework is found to be very sensitive to the synthetic protocol and although the stable loading level is close to M-1⊃AB1.0, higher loading levels can be achieved for the Zn, Co, and Ni frameworks prior to vacuum treatment, with a maximum composition for the Zn framework of Zn-1⊃AB1.3. The degree of pore contraction upon loading is modulated by the inherent flexibility of the metal-carboxylate paddlewheel unit in the framework, with the Zn-1⊃AB1.0 showing the biggest contraction of 6.2% and the more rigid Cu-1⊃AB1.0 contracting by only 1.7%. Upon heating, each composite shows a temperature-induced phase transition to an open-pore (op) framework, and the enthalpy and onset temperatures of the phase transition are affected by the framework flexibility. For all composites, UV irradiation causes trans → cis isomerization of the occluded AB molecules. The population of cis-AB at the photostationary state and the thermal stability of the occluded cis-AB molecules are also found to correlate with the flexibility of the framework. Over a full heating-cooling cycle between 0 and 200 °C, the energy stored within the metastable cis-AB molecules is released as heat, with a maximum energy density of 28.9 J g-1 for Zn-1⊃AB1.0. These findings suggest that controlled confinement of photoswitches within flexible frameworks is a potential strategy for the development of solid-solid phase change materials for energy storage.
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Affiliation(s)
- Kieran Griffiths
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, U.K
| | | | - John M Griffin
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, U.K.,Materials Science Institute, Lancaster University, Lancaster LA1 4YB, U.K
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15
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Cross C, Cervini L, Halcovitch NR, Griffin JM. Solid-state nuclear magnetic resonance study of polymorphism in tris(8-hydroxyquinolinate)aluminium. Magn Reson Chem 2021; 59:1024-1037. [PMID: 33729603 DOI: 10.1002/mrc.5147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/03/2021] [Accepted: 03/07/2021] [Indexed: 06/12/2023]
Abstract
Tris(8-hydroxyquinolinate)aluminium (Alq3 ) is a metal-organic coordination complex, which is a widely used electroluminescent material in organic light-emitting diode technology. Crystalline Alq3 is known to occur in five polymorphic forms (denoted α, β, γ, δ, and ε), although the structures of some of these polymorphs have been the subject of considerable debate. In particular, the structure of α-Alq3 , which is a model for the local structure in amorphous films used in devices, is highly complex and has never been conclusively solved. In this work, we use solid-state nuclear magnetic resonance (NMR) and density functional theory (DFT) calculations to investigate the local structure of four Alq3 samples. We find that the first structure proposed for α-Alq3 is inconsistent with all of the samples studied, and DFT calculations further suggest that this structure is energetically unfavourable. Instead, samples containing the meridional (mer) isomeric form are found to contain local structures consistent with ε-Alq3 , and a sample containing the facial (fac) isomeric form is consistent with a mixture of γ-Alq3 and δ-Alq3 . We also investigate the influence of different strategies for dispersion correction in DFT geometry optimisations. We find that a recently proposed modified semiempirical dispersion correction scheme gives good agreement with experiment. Furthermore, the DFT calculations also show that distinction between mer and fac isomers on the basis of ηQ that has been assumed in previous work is not always justified.
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Affiliation(s)
- Callum Cross
- Department of Chemistry, Lancaster University, Lancaster, UK
| | - Luca Cervini
- Department of Chemistry, Lancaster University, Lancaster, UK
| | | | - John M Griffin
- Department of Chemistry, Lancaster University, Lancaster, UK
- Materials Science Institute, Lancaster University, Lancaster, UK
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16
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Yeo CI, Tan YJ, Shiomitsu A, Chew J, Halcovitch NR, Tiekink ER. Crystal structure of bis[μ 2-( N, N-diethylcarbamodithioato-κ S:κ S,κ S′)]-bis(triethylphosphine- P)-di-silver(I), C 22H 50Ag 2N 2P 2S 4. Z KRIST-NEW CRYST ST 2020. [DOI: 10.1515/ncrs-2020-0317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C22H50Ag2N2P2S4, triclinic, P1̄ (no. 2), a = 9.0672(2) Å, b = 11.2091(3) Å, c = 16.6853(4) Å, α = 91.097(2)°, β = 90.363(2)°, γ = 110.989(2)°, V = 1582.85(7) Å3, Z = 2, R
gt(F) = 0.0241, wR
ref(F
2) = 0.0653, T = 100(2) K.
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Affiliation(s)
- Chien Ing Yeo
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Yi Jiun Tan
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Aya Shiomitsu
- Department of Biological Sciences, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Jactty Chew
- Department of Biological Sciences, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry , Lancaster University , Lancaster LA1 4YB , United Kingdom
| | - Edward R.T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
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17
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Tan YJ, Yeo CI, Halcovitch NR, Tiekink ER. Crystal structure of bis[μ 2-(pyrrolidine-1-carbodithioato-κ S:κ S,κ S′)]-bis(triethylphosphine-κ P)disilver(I), C 22H 46Ag 2N 2P 2S 4. Z KRIST-NEW CRYST ST 2020. [DOI: 10.1515/ncrs-2020-0319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C22H46Ag2N2P2S4, triclinic, P1̄ (no. 2), a = 10.2008(3) Å, b = 12.2058(3) Å, c = 13.2466(4) Å, α = 88.155(2)°, β = 87.256(2)°, γ = 69.324(2)°, V = 1541.12(8) Å3, Z = 2, R
gt(F) = 0.0237, wR
ref(F
2) = 0.0621, T = 100(2) K.
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Affiliation(s)
- Yi Jiun Tan
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Chien Ing Yeo
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry , Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - Edward R.T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
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18
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Danos L, Halcovitch NR, Wood B, Banks H, Coogan MP, Alderman N, Fang L, Dzurnak B, Markvart T. Silicon photosensitisation using molecular layers. Faraday Discuss 2020; 222:405-423. [PMID: 32115600 DOI: 10.1039/c9fd00095j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Silicon photosensitisation via energy transfer from molecular dye layers is a promising area of research for excitonic silicon photovoltaics. We present the synthesis and photophysical characterisation of vinyl and allyl terminated Si(111) surfaces decorated with perylene molecules. The functionalised silicon surfaces together with Langmuir-Blodgett (LB) films based on perylene derivatives were studied using a wide range of steady-state and time resolved spectroscopic techniques. Fluorescence lifetime quenching experiments performed on the perylene modified monolayers revealed energy transfer efficiencies to silicon of up to 90 per cent. We present a simple model to account for the near field interaction of a dipole emitter with the silicon surface and distinguish between the 'true' FRET region (<5 nm) and a different process, photon tunnelling, occurring for distances between 10-50 nm. The requirements for a future ultra-thin crystalline solar cell paradigm include efficient surface passivation and keeping a close distance between the emitter dipole and the surface. These are discussed in the context of existing limitations and questions raised about the finer details of the emitter-silicon interaction.
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Affiliation(s)
- Lefteris Danos
- Department of Chemistry, Energy Lancaster, Lancaster University, Lancaster, LA1 4YB, UK.
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19
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Britten TK, Kemmitt PD, Halcovitch NR, Coote SC. 1,2-Dihydropyridazines as Versatile Synthetic Intermediates. Synlett 2020. [DOI: 10.1055/s-0039-1690825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The reactivity of 1,2-dihydropyridazines under various conditions is described, leading to the formation of a variety of products, including 2-aminopyrroles, phenylenediamines, and several novel heterocyclic motifs.
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Affiliation(s)
| | - Paul D. Kemmitt
- Medicinal Chemistry, Research and Early Development, Oncology R & D, AstraZeneca
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20
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Janot C, Chagnoleau JB, Halcovitch NR, Muir J, Aïssa C. Palladium-Catalyzed Synthesis of α-Carbonyl-α'-(hetero)aryl Sulfoxonium Ylides: Scope and Insight into the Mechanism. J Org Chem 2020; 85:1126-1137. [PMID: 31808694 DOI: 10.1021/acs.joc.9b03032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite recent advances, a general method for the synthesis of α-carbonyl-α'-(hetero)aryl sulfoxonium ylides is needed to benefit more greatly from the potential safety advantages offered by these compounds over the parent diazo compounds. Herein, we report the palladium-catalyzed cross-coupling of aryl bromides and triflates with α-carbonyl sulfoxonium ylides. We also report the use of this method for the modification of an active pharmaceutical ingredient and for the synthesis of a key precursor of antagonists of the neurokinin-1 receptor. In addition, the mechanism of the reaction was inferred from several observations. Thus, the oxidative addition complex [(XPhos)PhPdBr] and its dimer were observed by 31P{1H} NMR, and these complexes were shown to be catalytically and kinetically competent. Moreover, a complex resulting from the transmetalation of [(XPhos)ArPdBr] (Ar = p-CF3-C6H4) with a model sulfoxonium ylide was observed by mass spectrometry. Finally, the partial rate law suggests that the transmetalation and the subsequent deprotonation are rate-determining in the catalytic cycle.
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Affiliation(s)
- Christopher Janot
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , United Kingdom
| | - Jean-Baptiste Chagnoleau
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , United Kingdom
| | - Nathan R Halcovitch
- Department of Chemistry , Lancaster University , Bailrigg , Lancaster LA1 4YB , United Kingdom
| | - James Muir
- Pharmaceutical Technology and Development , AstraZeneca Macclesfield Campus , Cheshire SK10 2NA , United Kingdom
| | - Christophe Aïssa
- Department of Chemistry , University of Liverpool , Crown Street , Liverpool L69 7ZD , United Kingdom
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21
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Kreaunakpan J, Chainok K, Halcovitch NR, Tiekink ERT, Pirojsirikul T, Saithong S. Crystal and mol-ecular structures of a binuclear mixed ligand complex of silver(I) with thio-cyanate and 1 H-1,2,4-triazole-5(4 H)-thione. Acta Crystallogr E Crystallogr Commun 2020; 76:42-47. [PMID: 31921450 PMCID: PMC6944082 DOI: 10.1107/s2056989019016359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 12/04/2019] [Indexed: 11/10/2022]
Abstract
The complete mol-ecule of the binuclear title complex, bis-[μ-1H-1,2,4-triazole-5(4H)-thione-κ2 S:S]bis-{(thio-cyanato-κS)[1H-1,2,4-triazole-5(4H)-thione-κS]silver(I)}, [Ag2(SCN)2(C2H3N3S)4], is generated by crystallographic inversion symmetry. The independent triazole-3-thione ligands employ the exocyclic-S atoms exclusively in coordination. One acts as a terminal S-ligand and the other in a bidentate (μ2) bridging mode to provide a link between two AgI centres. Each AgI atom is also coordinated by a terminal S-bound thio-cyanate ligand, resulting in a distorted AgS4 tetra-hedral coordination geometry. An intra-molecular N-H⋯S(thio-cyanate) hydrogen bond is noted. In the crystal, amine-N-H⋯S(thione), N-H⋯N(triazol-yl) and N-H⋯N(thio-cyanate) hydrogen bonds give rise to a three-dimensional architecture. The packing is consolidated by triazolyl-C-H⋯S(thio-cyanate), triazolyl-C-H⋯N(thiocyanate) and S⋯S [3.2463 (9) Å] inter-actions as well as face-to-face π-π stacking between the independent triazolyl rings [inter-centroid separation = 3.4444 (15) Å]. An analysis of the calculated Hirshfeld surfaces shows the three major contributors are due to N⋯H/H⋯N, S⋯H/H⋯S and C⋯H/H⋯C contacts, at 35.8, 19.4 and 12.7%, respectively; H⋯H contacts contribute only 7.6% to the overall surface.
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Affiliation(s)
- Janjira Kreaunakpan
- Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
| | - Kittipong Chainok
- Materials and Textile Technology, Faculty of Science and Technology, Thammasat University, Khlong Luang, Pathum Thani, 12121, Thailand
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Edward R. T. Tiekink
- Centre for Crystalline Materials, Faculty of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Teerapong Pirojsirikul
- Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
| | - Saowanit Saithong
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
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22
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Britten TK, Kemmitt PD, Halcovitch NR, Coote SC. 4-π-Photocyclization of 1,2-Dihydropyridazines: An Approach to Bicyclic 1,2-Diazetidines with Rich Synthetic Potential. Org Lett 2019; 21:9232-9235. [PMID: 31696716 DOI: 10.1021/acs.orglett.9b03613] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 4-π-photocyclization of a range of 1,2-dihydropyridazines is described, generating bicyclic 1,2-diazetidines in high yields on multigram scale. The key bicyclic 1,2-diazetidines are versatile synthetic intermediates and were easily converted into a range of novel derivatives, including functionalized 1,2-diazetidines, cyclobutenes, cyclobutanes, and 1,3-dienes.
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Affiliation(s)
- Thomas K Britten
- Department of Chemistry , Lancaster University , Bailrigg, Lancaster , LA1 4YB , U.K
| | - Paul D Kemmitt
- Medicinal Chemistry, Research and Early Development, Oncology R & D , AstraZeneca , Cambridge , CB10 1XL , U.K
| | - Nathan R Halcovitch
- Department of Chemistry , Lancaster University , Bailrigg, Lancaster , LA1 4YB , U.K
| | - Susannah C Coote
- Department of Chemistry , Lancaster University , Bailrigg, Lancaster , LA1 4YB , U.K
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23
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Tan SL, Halcovitch NR, Tiekink ERT. N, N'-Bis(pyridin-4-ylmeth-yl)oxalamide benzene monosolvate: crystal structure, Hirshfeld surface analysis and computational study. Acta Crystallogr E Crystallogr Commun 2019; 75:1133-1139. [PMID: 31417779 PMCID: PMC6690468 DOI: 10.1107/s2056989019009551] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/03/2019] [Indexed: 11/10/2022]
Abstract
The asymmetric unit of the title 1:1 solvate, C14H14N4O2·C6H6 [systematic name of the oxalamide mol-ecule: N,N'-bis-(pyridin-4-ylmeth-yl)ethanedi-amide], comprises a half mol-ecule of each constituent as each is disposed about a centre of inversion. In the oxalamide mol-ecule, the central C2N2O2 atoms are planar (r.m.s. deviation = 0.0006 Å). An intra-molecular amide-N-H⋯O(amide) hydrogen bond is evident, which gives rise to an S(5) loop. Overall, the mol-ecule adopts an anti-periplanar disposition of the pyridyl rings, and an orthogonal relationship is evident between the central plane and each terminal pyridyl ring [dihedral angle = 86.89 (3)°]. In the crystal, supra-molecular layers parallel to (10) are generated owing the formation of amide-N-H⋯N(pyrid-yl) hydrogen bonds. The layers stack encompassing benzene mol-ecules which provide the links between layers via methyl-ene-C-H⋯π(benzene) and benzene-C-H⋯π(pyrid-yl) inter-actions. The specified contacts are indicated in an analysis of the calculated Hirshfeld surfaces. The energy of stabilization provided by the conventional hydrogen bonding (approximately 40 kJ mol-1; electrostatic forces) is just over double that by the C-H⋯π contacts (dispersion forces).
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Affiliation(s)
- Sang Loon Tan
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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24
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Britten TK, Akien GR, Kemmitt PD, Halcovitch NR, Coote SC. An efficient preparation of 1,2-dihydropyridazines through a Diels-Alder/palladium-catalysed elimination sequence. Tetrahedron Lett 2019. [DOI: 10.1016/j.tetlet.2019.04.054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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25
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Dale BL, Halcovitch NR, Peach MJG, Griffin JM. Investigation of structure and dynamics in a photochromic molecular crystal by NMR crystallography. Magn Reson Chem 2019; 57:230-242. [PMID: 30452093 DOI: 10.1002/mrc.4805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/01/2018] [Accepted: 11/07/2018] [Indexed: 06/09/2023]
Abstract
A photochromic anil, N-(3,5-di-t-butylsalicylidene)-4-amino-pyridine, has been studied by single-crystal X-ray diffraction, multinuclear magic-angle spinning NMR, and first-principles density functional theory (DFT) calculations. Interpretation of the solid-state NMR data on the basis of calculated chemical shifts confirms the structure is primarily composed of molecules in the ground-state enol tautomer, whereas thermally activated cis-keto and photoisomerised trans-keto states exist as low-level defects with populations that are too low to detect experimentally. Variable temperature 13 C NMR data reveal evidence for solid-state dynamics, which is found to be associated with fast rotational motion of t-butyl groups and 180° flips of the pyridine ring, contrasting the time-averaged structure obtained by X-ray diffraction. Comparison of calculated chemical shifts for the full crystal structure and an isolated molecule also reveals evidence for an intermolecular hydrogen bond involving the pyridine ring and an adjacent imine carbon, which facilitates the flipping motion. The DFT calculations also reveal that the molecular conformation in the crystal structure is very close to the energetic minimum for an isolated molecule, indicating that the ring dynamics arise as a result of considerable steric freedom of the pyridine ring and which also allows the molecule to adopt a favourable conformation for photochromism.
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Affiliation(s)
- Benjamin L Dale
- Department of Chemistry, Lancaster University, Lancaster, UK
| | | | | | - John M Griffin
- Department of Chemistry, Lancaster University, Lancaster, UK
- Materials Science Institute, Lancaster University, Lancaster, UK
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26
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Affiliation(s)
- Rodney T. Brown
- School of Chemistry and Chemical Engineering; Queen's University Belfast; BT9 5AG Belfast Northern Ireland UK
| | - Nicholas C. Fletcher
- Department of Chemistry; Lancaster University; Bailrigg 4YB Lancaster, LA1 UK
- School of Chemistry and Chemical Engineering; Queen's University Belfast; BT9 5AG Belfast Northern Ireland UK
| | - Lefteris Danos
- Department of Chemistry; Lancaster University; Bailrigg 4YB Lancaster, LA1 UK
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27
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Mun LS, Halcovitch NR, Tiekink ER. Crystal structure of chlorido-methanol-( N-(2-(oxy)-3-methoxybenzylidene)pyridine-4-carbohydrazonato-κ 3
O, N, O′)-(4-methylphenyl)methyl-tin(IV), C 23H 24ClN 3O 4Sn. Z KRIST-NEW CRYST ST 2018. [DOI: 10.1515/ncrs-2017-0410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C23H24ClN3O4Sn, triclinic, P1̄ (no. 2), a = 9.7536(2) Å, b = 10.0755(2) Å, c = 12.4215(3) Å, α = 84.928(2)°, β = 72.544(2)°, γ = 74.382(2)°, V = 1121.44(4) Å3, Z = 2, R
gt(F) = 0.021, wR
ref(F
2) = 0.054, T = 100(2) K.
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Affiliation(s)
- Lee See Mun
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University , 47500 Bandar Sunway , Selangor Darul Ehsan , Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - Edward R.T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University , 47500 Bandar Sunway , Selangor Darul Ehsan , Malaysia
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28
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Tan YJ, Yeo CI, Halcovitch NR, Tiekink ER. Crystal structure of bis( μ
2-diethyldithiocarbamato- κ
3
S, S′: S′)-bis(tricyclohexylphosphane-κ P)dicopper(I), C 46H 86Cu 2N 2P 2S 4. Z KRIST-NEW CRYST ST 2018. [DOI: 10.1515/ncrs-2017-0402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C46H86Cu2N2P2S4, triclinic, P1̄ (no. 2), a = 9.9626(3) Å, b = 11.0489(3) Å, c = 12.3604(3) Å, α = 106.205(3)°, β = 99.165(2)°, γ = 100.306(3)°, V = 1253.53(6) Å3, Z = 1, R
gt(F) = 0.0232, wR
ref(F
2) = 0.0555, T = 100(2) K.
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Affiliation(s)
- Yi Jiun Tan
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Chien Ing Yeo
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry , Lancaster University , Lancaster LA1 4YB , United Kingdom
| | - Edward R.T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway, Selangor Darul Ehsan , Malaysia
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29
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Heard PJ, Halcovitch NR, Mun LS, Tiekink ER. Crystal structure of bis(μ 2-di- n-butyldithiocarbamato-κ 3
S, S′: S;κ 3
S: S: S′)-hexacarbonyl-di-rhenium(I), C 24H 36N 2O 6Re 2. Z KRIST-NEW CRYST ST 2018. [DOI: 10.1515/ncrs-2017-0370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C24H36N2O6Re2, triclinic, P1̅ (no. 2), a = 10.3013(2) Å, b = 11.3471(2) Å, c = 14.5967(3) Å, α = 72.540(2)°, β = 73.074(2)°, γ = 85.369(2)°, V = 1557.05(6) Å3, Z = 2, R
gt(F) = 0.0214, wR
ref(F
2) = 0.0466, T = 100(2) K.
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Affiliation(s)
- Peter J. Heard
- Office of the Provost, Sunway University , 47500 Bandar Sunway , Selangor Darul Ehsan , Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry , Lancaster University , Lancaster LA1 4YB , United Kingdom
| | - Lee See Mun
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University , 47500 Bandar Sunway , Selangor Darul Ehsan , Malaysia
| | - Edward R.T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University , 47500 Bandar Sunway , Selangor Darul Ehsan , Malaysia
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30
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Lim FPL, Dolzhenko AV, Halcovitch NR, Tiekink ER. Crystal structure of 7-(4-methylphenyl)imidazo[1,2- a][1,3,5]triazin-4-amine, C 12H 11N 5. Z KRIST-NEW CRYST ST 2018. [DOI: 10.1515/ncrs-2017-0371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C12H11N5, monoclinic, P21/n (no. 14), a = 7.3455(1) Å, b = 12.2470(1) Å, c = 12.1689(1) Å, β = 103.505(1)°, V = 1064.45(2) Å3, Z = 4, R
gt(F) = 0.0365, wR
ref(F
2) = 0.0987, T = 100 K.
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Affiliation(s)
- Felicia Phei Lin Lim
- School of Pharmacy, Monash University Malaysia , Jalan Lagoon Selatan, Bandar Sunway , Selangor Darul Ehsan 47500 , Malaysia
| | - Anton V. Dolzhenko
- School of Pharmacy, Monash University Malaysia , Jalan Lagoon Selatan, Bandar Sunway , Selangor Darul Ehsan 47500 , Malaysia
| | | | - Edward R.T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology , Sunway University , 47500 Bandar Sunway , Selangor Darul Ehsan , Malaysia
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Tan YJ, Yeo CI, Halcovitch NR, Tiekink ER. Crystal structure of bis(μ2-pyrrolidine-1-carbodithioato-κ3S,S′:S;κ3S:S:S′)-bis(tricyclohexylphosphane-P)-di-copper(I), C46H82Cu2N2P2S4. Z KRIST-NEW CRYST ST 2018. [DOI: 10.1515/ncrs-2017-0406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractC46H82Cu2N2P2S4, triclinic, P1̄ (no. 2), a = 11.6189(2) Å, b = 12.2846(2) Å, c = 18.1744(2) Å, α = 97.3210(10)°, β = 106.3080(10)°, γ = 99.312(2)°, V = 2415.65(7) Å3, Z = 2, Rgt(F) = 0.025, wRref(F2) = 0.066, T = 100(2) K.
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Affiliation(s)
- Yi Jiun Tan
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Chien Ing Yeo
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Edward R.T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Farrow CMA, Akien GR, Halcovitch NR, Platts JA, Coogan MP. Self-assembly of singlet-emitting double-helical silver dimers: the curious coordination chemistry and fluorescence of bisquinolylpyridone. Dalton Trans 2018; 47:3906-3912. [DOI: 10.1039/c7dt04744d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The previously unreported ligand 2,6-bis(2-quinolyl)-4(1H)-pyridone spontaneously assembles into double helical dimers with Ag+ – its fluorescence is BLUESHIFTED upon complexation.
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Affiliation(s)
| | | | | | | | - M. P. Coogan
- Department of Chemistry
- Lancaster University
- Lancaster
- UK
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Barday M, Janot C, Halcovitch NR, Muir J, Aïssa C. Cross-Coupling of α-Carbonyl Sulfoxonium Ylides with C-H Bonds. Angew Chem Int Ed Engl 2017; 56:13117-13121. [PMID: 28853234 DOI: 10.1002/anie.201706804] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 08/08/2017] [Indexed: 11/10/2022]
Abstract
The functionalization of carbon-hydrogen bonds in non-nucleophilic substrates using α-carbonyl sulfoxonium ylides has not been so far investigated, despite the potential safety advantages that such reagents would provide over either diazo compounds or their in situ precursors. Described herein are the cross-coupling reactions of sulfoxonium ylides with C(sp2 )-H bonds of arenes and heteroarenes in the presence of a rhodium catalyst. The reaction proceeds by a succession of C-H activation, migratory insertion of the ylide into the carbon-metal bond, and protodemetalation, the last step being turnover-limiting. The method is applied to the synthesis of benz[c]acridines when allied to an iridium-catalyzed dehydrative cyclization.
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Affiliation(s)
- Manuel Barday
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Christopher Janot
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Nathan R Halcovitch
- Department of Chemistry, Lancaster University, Bailrigg, Lancaster, LA1 4YB, UK
| | - James Muir
- Pharmaceutical Technology and Development, AstraZeneca R&D, Silk Road Business Park, Charter Way, Macclesfield, Cheshire, SK10 2NA, UK
| | - Christophe Aïssa
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
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Zaldi NB, Hussen RSD, Lee SM, Halcovitch NR, Jotani MM, Tiekink ERT. Secondary bonding in di-methyl-bis-(morpholine-4-carbodi-thio-ato-κ 2S, S')tin(IV): crystal structure and Hirshfeld surface analysis. Acta Crystallogr E Crystallogr Commun 2017; 73:842-848. [PMID: 28638641 PMCID: PMC5458306 DOI: 10.1107/s2056989017006855] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 05/07/2017] [Indexed: 11/10/2022]
Abstract
The title compound, [Sn(CH3)2(C5H8NOS2)2], has the SnIV atom bound by two methyl groups which lie over the weaker Sn-S bonds formed by two asymmetrically chelating di-thio-carbamate ligands so that the coordination geometry is skew-trapezoidal bipyramidal. The most prominent feature of the mol-ecular packing are secondary Sn⋯S inter-actions [Sn⋯S = 3.5654 (7) Å] that lead to centrosymmetric dimers. These are connected into a three-dimensional architecture via methyl-ene-C-H⋯S and methyl-C-H⋯O(morpholino) inter-actions. The Sn⋯S inter-actions are clearly evident in the Hirshfeld surface analysis of the title compound along with a number of other inter-molecular contacts.
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Affiliation(s)
| | | | - See Mun Lee
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Mukesh M. Jotani
- Department of Physics, Bhavan’s Sheth R. A. College of Science, Ahmedabad, Gujarat 380 001, India
| | - Edward R. T. Tiekink
- Research Centre for Chemical Crystallography, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Tan YJ, Yeo CI, Halcovitch NR, Jotani MM, Tiekink ERT. μ 3-Chlorido-μ 2-chlorido-(μ 3-pyrrolidine-1-carbo-dithio-ato-κ 4S: S, S': S')tris-[(tri-ethyl-phosphane-κ P)copper(I)]: crystal structure and Hirshfeld surface analysis. Acta Crystallogr E Crystallogr Commun 2017; 73:720-725. [PMID: 28529784 PMCID: PMC5418792 DOI: 10.1107/s2056989017005382] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 04/10/2017] [Indexed: 11/17/2022]
Abstract
The title trinuclear compound, [Cu3(C5H8NS2)Cl2(C6H15P)3], has the di-thio-carbamate ligand symmetrically chelating one CuI atom and each of the S atoms bridging to another CuI atom. Both chloride ligands are bridging, one being μ3- and the other μ2-bridging. Each Et3P ligand occupies a terminal position. Two of the CuI atoms exist within Cl2PS donor sets and the third is based on a ClPS2 donor set, with each coordination geometry based on a distorted tetra-hedron. The constituents defining the core of the mol-ecule, i.e. Cu3Cl2S2, occupy seven corners of a distorted cube. In the crystal, linear supra-molecular chains along the c axis are formed via phosphane-methyl-ene-C-H⋯Cl and pyrrolidine-methyl-ene-C-H⋯π(chelate) inter-actions, and these chains pack without directional inter-actions between them. An analysis of the Hirshfeld surface points to the predominance of H atoms at the surface, i.e. contributing 86.6% to the surface, and also highlights the presence of C-H⋯π(chelate) inter-actions.
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Affiliation(s)
- Yi Jiun Tan
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Chien Ing Yeo
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Mukesh M. Jotani
- Department of Physics, Bhavan’s Sheth R. A. College of Science, Ahmedabad, Gujarat 380001, India
| | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Amin NABM, Hussen RSD, Lee SM, Halcovitch NR, Jotani MM, Tiekink ERT. trans-Di-chlorido-bis-(dimethyl sulfoxide-κ O)bis-(4-fluoro-benzyl-κ C1)tin(IV): crystal structure and Hirshfeld surface analysis. Acta Crystallogr E Crystallogr Commun 2017; 73:667-672. [PMID: 28529772 PMCID: PMC5418780 DOI: 10.1107/s2056989017005072] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 04/02/2017] [Indexed: 11/10/2022]
Abstract
The SnIV atom in the title diorganotin compound, [Sn(C7H6F)2Cl2(C2H6OS)2], is located on a centre of inversion, resulting in the C2Cl2O2 donor set having an all-trans disposition of like atoms. The coordination geometry approximates an octa-hedron. The crystal features C-H⋯F, C-H⋯Cl and C-H⋯π inter-actions, giving rise to a three-dimensional network. The respective influences of the Cl⋯H/H⋯Cl and F⋯H/H⋯F contacts to the mol-ecular packing are clearly evident from the analysis of the Hirshfeld surface.
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Affiliation(s)
| | | | - See Mun Lee
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Mukesh M. Jotani
- Department of Physics, Bhavan’s Sheth R. A. College of Science, Ahmedabad, Gujarat 380001, India
| | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Abstract
BACKGROUND A key aim of asthma care is to empower each person to take control of his or her own condition. A personalised asthma action plan (PAAP), also known as a written action plan, an individualised action plan, or a self-management action plan, contributes to this endeavour. A PAAP includes individualised self-management instructions devised collaboratively with the patient to help maintain asthma control and regain control in the event of an exacerbation. A PAAP includes baseline characteristics (such as lung function), maintenance medication and instructions on how to respond to increasing symptoms and when to seek medical help. OBJECTIVES To evaluate the effectiveness of PAAPs used alone or in combination with education, for patient-reported outcomes, resource use and safety among adults with asthma. SEARCH METHODS We searched the Cochrane Airways Group Specialised Register of trials, clinical trial registers, reference lists of included studies and review articles, and relevant manufacturers' websites up to 14 September 2016. SELECTION CRITERIA We included parallel randomised controlled trials (RCTs), both blinded and unblinded, that evaluated written PAAPs in adults with asthma. Included studies compared PAAP alone versus no PAAP, and/or PAAP plus education versus education alone. DATA COLLECTION AND ANALYSIS Two review authors independently extracted study characteristics and outcome data and assessed risk of bias for each included study. Primary outcomes were number of participants reporting at least one exacerbation requiring an emergency department (ED) visit or hospitalisation, asthma symptom scores on a validated scale and adverse events (all causes). Secondary outcomes were quality of life measured on a validated scale, number of participants reporting at least one exacerbation requiring systemic corticosteroids, respiratory function and days lost from work or study. We used a random-effects model for all analyses and standard Cochrane methods throughout. MAIN RESULTS We identified 15 studies described in 27 articles that met our inclusion criteria. These 15 included studies randomised a total of 3062 participants (PAAP vs no PAAP: 2602 participants; PAAP plus education vs education alone: 460 participants). Ten studies (eight PAAP vs no PAAP; two PAAP plus education vs education alone) provided outcome data that contributed to quantitative analyses. The overall quality of evidence was rated as low or very low.Fourteen studies lasted six months or longer, and the remaining study lasted for 14 weeks. When reported, mean age ranged from 22 to 49 years and asthma severity ranged from mild to severe/high risk. PAAP alone compared with no PAAPResults showed no clear benefit or harm associated with PAAPs in terms of the number of participants requiring an ED visit or hospitalisation for an exacerbation (odds ratio (OR) 0.75, 95% confidence interval (CI) 0.45 to 1.24; 1385 participants; five studies; low-quality evidence), change from baseline in asthma symptoms (mean difference (MD) -0.16, 95% CI -0.25 to - 0.07; 141 participants; one study; low-quality evidence) or the number of serious adverse events, including death (OR 3.26, 95% CI 0.33 to 32.21; 125 participants; one study; very low-quality evidence). Data revealed a statistically significant improvement in quality of life scores for those receiving PAAP compared with no PAAP (MD 0.18, 95% CI 0.05 to 0.30; 441 participants; three studies; low-quality evidence), but this was below the threshold for a minimum clinically important difference (MCID). Results also showed no clear benefit or harm associated with PAAPs on the number of participants reporting at least one exacerbation requiring oral corticosteroids (OR 1.45, 95% CI 0.84 to 2.48; 1136 participants; three studies; very low-quality evidence) nor on respiratory function (change from baseline forced expiratory volume in one second (FEV1): MD -0.04 L, 95% CI -0.25L to 0.17 L; 392 participants; three studies; low-quality evidence). In one study, PAAPs were associated with significantly fewer days lost from work or study (MD -6.20, 95% CI -7.32 to - 5.08; 74 participants; low-quality evidence). PAAP plus education compared with education aloneResults showed no clear benefit or harm associated with adding a PAAP to education in terms of the number of participants requiring an ED visit or hospitalisation for an exacerbation (OR 1.08, 95% CI 0.27 to 4.32; 70 participants; one study; very low-quality evidence), change from baseline in asthma symptoms (MD -0.10, 95% CI -0.54 to 0.34; 70 participants; one study; low-quality evidence), change in quality of life scores from baseline (MD 0.13, 95% CI -0.13 to 0.39; 174 participants; one study; low-quality evidence) and number of participants requiring oral corticosteroids for an exacerbation (OR 0.28, 95% CI 0.07 to 1.12; 70 participants; one study; very low-quality evidence). No studies reported serious adverse events, respiratory function or days lost from work or study. AUTHORS' CONCLUSIONS Analysis of available studies was limited by variable reporting of primary and secondary outcomes; therefore, it is difficult to draw firm conclusions related to the effectiveness of PAAPs in the management of adult asthma. We found no evidence from randomised controlled trials of additional benefit or harm associated with use of PAAP versus no PAAP, or PAAP plus education versus education alone, but we considered the quality of the evidence to be low or very low, meaning that we cannot be confident in the magnitude or direction of reported treatment effects. In the context of this caveat, we found no observable effect on the primary outcomes of hospital attendance with an asthma exacerbation, asthma symptom scores or adverse events. We recommend further research with a particular focus on key patient-relevant outcomes, including exacerbation frequency and quality of life, in a broad spectrum of adults, including those over 60 years of age.
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Affiliation(s)
- Timothy L Gatheral
- University Hospitals of Morecambe Bay NHS Foundation TrustRespiratory MedicineLancasterUK
| | - Alison Rushton
- Lancashire Care NHS Foundation TrustEducation, Training and Professional Development, Nursing & Quality DirectoratePrestonUK
| | - David JW Evans
- Lancaster UniversityLancaster Health HubLancasterUKLA1 4YG
| | | | | | - Gemma Whiteley
- Lancashire Teaching Hospitals NHS Foundation Trust, Royal Preston HospitalResearch and InnovationPrestonUK
| | | | - Sally Spencer
- Edge Hill UniversityPostgraduate Medical InstituteSt Helens RoadOrmskirkLancashireUKL39 4QP
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Tan YJ, Yeo CI, Halcovitch NR, Jotani MM, Tiekink ERT. A triclinic polymorph of tri-cyclo-hexyl-phosphane sulfide: crystal structure and Hirshfeld surface analysis. Acta Crystallogr E Crystallogr Commun 2017; 73:493-499. [PMID: 28435705 PMCID: PMC5382606 DOI: 10.1107/s205698901700353x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 03/04/2017] [Indexed: 11/13/2023]
Abstract
The title compound, (C6H11)3PS (systematic name: tri-cyclo-hexyl-λ5-phosphane-thione), is a triclinic (P-1, Z' = 1) polymorph of the previously reported ortho-rhom-bic form (Pnma, Z' = 1/2) [Kerr et al. (1977 ▸). Can. J. Chem. 55, 3081-3085; Reibenspies et al. (1996 ▸). Z. Kristallogr. 211, 400]. While conformational differences exist between the non-symmetric mol-ecule in the triclinic polymorph, cf. the mirror-symmetric mol-ecule in the ortho-rhom-bic form, these differences are not chemically significant. The major feature of the mol-ecular packing in the triclinic polymorph is the formation of linear chains along the a axis sustained by methine-C-H⋯S(thione) inter-actions. The chains pack with no directional inter-actions between them. The analysis of the Hirshfeld surface for both polymorphs indicates a high degree of similarity, being dominated by H⋯H (ca 90%) and S⋯H/H⋯S contacts.
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Affiliation(s)
- Yi Jiun Tan
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Chien Ing Yeo
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Mukesh M. Jotani
- Department of Physics, Bhavan’s Sheth R. A. College of Science, Ahmedabad, Gujarat 380001, India
| | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Lee SM, Halcovitch NR, Jotani MM, Tiekink ERT. N'-[1-(5-Bromo-2-hy-droxy-phen-yl)ethyl-idene]isonicotinohydrazide monohydrate: crystal structure and Hirshfeld surface analysis. Acta Crystallogr E Crystallogr Commun 2017; 73:630-636. [PMID: 28435737 PMCID: PMC5382638 DOI: 10.1107/s2056989017004790] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 03/28/2017] [Indexed: 11/22/2022]
Abstract
In the title isonicotinohydrazide hydrate, C14H12BrN3O2·H2O {systematic name: N'-[(1E)-1-(5-bromo-2-hy-droxy-phen-yl)ethyl-idene]pyridine-4-carbohydrazide monohydrate}, the central CN2O region of the organic mol-ecule is planar and the conformation about the imine-C=N bond is E. While an intra-molecular hy-droxy-O-H⋯N(imine) hydrogen bond is evident, the dihedral angle between the central residue and the benzene rings is 48.99 (9)°. Overall, the mol-ecule is twisted, as seen in the dihedral angle of 71.79 (6)° between the outer rings. In the crystal, hydrogen-bonding inter-actions, i.e. hydrazide-N-H⋯O(water), water-O-H⋯O(carbon-yl) and water-O-H⋯N(pyrid-yl), lead to supra-molecular ribbons along the a-axis direction. Connections between these, leading to a three-dimensional architecture, are mediated by Br⋯Br halogen bonding [3.5366 (3) Å], pyridyl-C-H⋯O(carbon-yl) as well as weak π-π inter-actions [inter-centroid separation between benzene rings = 3.9315 (12) Å]. The Hirshfeld surface analysis reveals the importance of hydrogen atoms in the supra-molecular connectivity as well as the influence of the Br⋯Br halogen bonding.
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Affiliation(s)
- See Mun Lee
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Mukesh M. Jotani
- Department of Physics, Bhavan’s Sheth R. A. College of Science, Ahmedabad, Gujarat 380001, India
| | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Rosely SNBM, Hussen RSD, Lee SM, Halcovitch NR, Jotani MM, Tiekink ERT. [ N'-(4-Dec-yloxy-2-oxido-benzyl-idene)-3-hy-droxy-2-naphtho-hydrazidato-κ 3N, O, O']di-methyl-tin(IV): crystal structure and Hirshfeld surface analysis. Acta Crystallogr E Crystallogr Commun 2017; 73:390-396. [PMID: 28316817 PMCID: PMC5347062 DOI: 10.1107/s2056989017002365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 02/11/2017] [Indexed: 11/10/2022]
Abstract
The title diorganotin compound, [Sn(CH3)2(C28H32N2O4)], features a distorted SnC2NO2 coordination geometry almost inter-mediate between ideal trigonal-bipyramidal and square-pyramidal. The dianionic Schiff base ligand coordinates in a tridentate fashion via two alkoxide O and hydrazinyl N atoms; an intra-molecular hy-droxy-O-H⋯N(hydrazin-yl) hydrogen bond is noted. The alk-oxy chain has an all-trans conformation, and to the first approximation, the mol-ecule has local mirror symmetry relating the two Sn-bound methyl groups. Supra-molecular layers sustained by imine-C-H⋯O(hy-droxy), π-π [between dec-yloxy-substituted benzene rings with an inter-centroid separation of 3.7724 (13) Å], C-H⋯π(arene) and C-H⋯π(chelate ring) inter-actions are formed in the crystal; layers stack along the c axis with no directional inter-actions between them. The presence of C-H⋯π(chelate ring) inter-actions in the crystal is clearly evident from an analysis of the calculated Hirshfeld surface.
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Affiliation(s)
| | | | - See Mun Lee
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Nathan R. Halcovitch
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Mukesh M. Jotani
- Department of Physics, Bhavan’s Sheth R. A. College of Science, Ahmedabad, Gujarat 380001, India
| | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Tan SL, Lee SM, Heard PJ, Halcovitch NR, Tiekink ERT. fac-Aceto-nitrile-tricarbon-yl(di-methyl-carbamodi-thio-ato-κ 2S, S')rhenium(I): crystal structure and Hirshfeld surface analysis. Acta Crystallogr E Crystallogr Commun 2017; 73:213-218. [PMID: 28217345 PMCID: PMC5290568 DOI: 10.1107/s2056989017000755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 01/15/2017] [Indexed: 11/10/2022]
Abstract
The title compound, [Re(C3H6NS2)(C2H3N)(CO)3], features an octa-hedrally coordinated ReI atom within a C3NS2 donor set defined by three carbonyl ligands in a facial arrangement, an aceto-nitrile N atom and two S atoms derived from a symmetrically coordinating di-thio-carbamate ligand. In the crystal, di-thio-carbamate-methyl-H⋯O(carbon-yl) inter-actions lead to supra-molecular chains along [36-1]; both di-thio-carbamate S atoms participate in intra-molecular methyl-H⋯S inter-actions. Further but weaker aceto-nitrile-C-H⋯O(carbonyl) inter-actions assemble mol-ecules in the ab plane. The nature of the supra-molecular assembly was also probed by a Hirshfeld surface analysis. Despite their weak nature, the C-H⋯O contacts are predominant on the Hirshfeld surface and, indeed, on those of related [Re(CO)3(C3H6NS2)L] structures.
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Affiliation(s)
- Sang Loon Tan
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - See Mun Lee
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Peter J. Heard
- Office of the Provost, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | | | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, School of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Abstract
BACKGROUND Asthma is a condition of the airways affecting more than 300 million adults and children worldwide. National and international guidelines recommend titrating up the dose of inhaled corticosteroids (ICS) to gain symptom control at the lowest possible dose because long-term use of higher doses of ICS carries a risk of systemic adverse events. For patients whose asthma symptoms are controlled on moderate or higher doses of ICS, it may be possible to reduce the dose of ICS without compromising symptom control. OBJECTIVES To evaluate the evidence for stepping down ICS treatment in adults with well-controlled asthma who are already receiving a moderate or high dose of ICS. SEARCH METHODS We identified trials from the Specialised Register of the Cochrane Airways Group and conducted a search of ClinicalTrials.gov (www.ClinicalTrials.gov) and the World Health Organization (WHO) trials portal (www.who.int/ictrp/en/). We searched all databases from their inception with no restriction on language. We also searched the reference lists of included studies and relevant reviews. We performed the most recent search in July 2016. SELECTION CRITERIA We included randomised controlled trials (RCTs) of at least 12 weeks' duration and excluded cross-over trials. We looked for studies of adults (aged ≥ 18 years) whose asthma had been well controlled for a minimum of three months on at least a moderate dose of ICS. We excluded studies that enrolled participants with any other respiratory comorbidity.We included trials comparing a reduction in the dose of ICS versus no change in the dose of ICS in people with well-controlled asthma who a) were not taking a concomitant long-acting beta agonist (LABA; comparison 1), and b) were taking a concomitant LABA (comparison 2). DATA COLLECTION AND ANALYSIS Two review authors independently screened the search results for included studies, extracted data on prespecified outcomes of interest and assessed the risk of bias of included studies; we resolved disagreements by discussion with a third review author. We analysed dichotomous data as odds ratios (ORs) using study participants as the unit of analysis and analysed continuous data as mean differences (MDs). We used a random-effects model. We rated all outcomes using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) system and presented results in 'Summary of findings' tables. MAIN RESULTS We included six studies, which randomised a total of 1654 participants (ICS dose reduction, no concomitant LABA (comparison 1): n = 892 participants, three RCTs; ICS dose reduction, concomitant LABA (comparison 2): n = 762 participants, three RCTs). All included studies were RCTs with a parallel design that compared a fixed dose of ICS versus a 50% to 60% reduction in the dose of ICS in adult participants with well-controlled asthma. The duration of the treatment period ranged from 12 to 52 weeks (mean duration 21 weeks; median duration 14 weeks). Two studies were performed in the setting of primary care, two were performed in the secondary care setting and two reported no information on setting.Meta-analysis was hampered by the small number of studies contributing to each comparison, combined with heterogeneity among outcomes reported in the included studies. We found the quality of synthesised evidence to be low or very low for most outcomes considered because of a risk of bias (principally, selective reporting), imprecision and indirectness. Although we found no statistically significant or clinically relevant differences between groups with respect to any of the primary or secondary outcomes considered in this review, the data were insufficient to rule out benefit or harm. AUTHORS' CONCLUSIONS The strength of the evidence is not sufficient to determine whether stepping down the dose of ICS is of net benefit (in terms of fewer adverse effects) or harm (in terms of reduced effectiveness of treatment) for adult patients with well-controlled asthma. A small number of relevant studies and varied outcome measures limited the number of meta-analyses that we could perform. Additional well-designed RCTs of longer duration are needed to inform clinical practice regarding use of a 'stepping down ICS' strategy for patients with well-controlled asthma.
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Affiliation(s)
| | - David JW Evans
- Lancaster UniversityLancaster Health HubLancasterUKLA1 4YG
| | | | - Paul A Marsden
- Lancashire Teaching Hospitals NHS Foundation Trust, Royal Preston HospitalLancashire Chest CentrePrestonUK
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Lim FPL, Low ST, Ho ELK, Halcovitch NR, Tiekink ERT, Dolzhenko AV. A multicomponent reaction of 2-aminoimidazoles: microwave-assisted synthesis of novel 5-aza-7-deaza-adenines. RSC Adv 2017. [DOI: 10.1039/c7ra11305f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An efficient and highly selective multicomponent synthesis of 4-aminoimidazo[1,2-a]triazines, which are 5-aza-7-deaza-isosteres of adenine, was developed.
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Affiliation(s)
| | - Szy Teng Low
- School of Pharmacy
- Monash University Malaysia
- Bandar Sunway
- Malaysia
| | | | | | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials
- School of Science and Technology
- Sunway University
- Bandar Sunway
- Malaysia
| | - Anton V. Dolzhenko
- School of Pharmacy
- Monash University Malaysia
- Bandar Sunway
- Malaysia
- School of Pharmacy
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Tan SL, Yeo CI, Heard PJ, Akien GR, Halcovitch NR, Tiekink ERT. [ N, N-Bis(2-hy-droxy-eth-yl)di-thio-carbamato-κ 2S, S']bis-(tri-phenyl-phosphane-κ P)copper(I) chloro-form monosolvate: crystal structure, Hirshfeld surface analysis and solution NMR measurements. Acta Crystallogr E Crystallogr Commun 2016; 72:1799-1805. [PMID: 27980834 PMCID: PMC5137612 DOI: 10.1107/s2056989016017837] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 11/07/2016] [Indexed: 11/11/2022]
Abstract
The title compound, [Cu(C5H5NO2S2)(C18H15P)2]·CHCl3, features a tetra-hedrally coordinated CuI atom within a P2S2 donor set defined by two phosphane P atoms and by two S atoms derived from a symmetrically coordinating di-thio-carbamate ligand. Both intra- and inter-molecular hy-droxy-O-H⋯O(hydroxy) hydrogen bonding is observed: the former closes an eight-membered {⋯HOC2NC2O} ring, whereas the latter connects centrosymmetrically related mol-ecules into dimeric aggregates via eight-membered {⋯H-O⋯H-O}2 synthons. The complex mol-ecules are arranged to form channels along the c axis in which reside the chloro-form mol-ecules, being connected by Cl⋯π(arene) and short S⋯Cl [3.3488 (9) Å] inter-actions. The inter-molecular inter-actions have been investigated further by Hirshfeld surface analysis, which shows the conventional hydrogen bonding to be very localized with the main contributors to the surface, at nearly 60%, being H⋯H contacts. Solution NMR studies indicate that whilst the same basic mol-ecular structure is retained in solution, the tri-phenyl-phosphane ligands are highly labile, exchanging rapidly with free Ph3P at room temperature.
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Affiliation(s)
- Sang Loon Tan
- Research Centre for Crystalline Materials, Faculty of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Chien Ing Yeo
- Research Centre for Crystalline Materials, Faculty of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Peter J. Heard
- Office of the Provost, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
| | - Geoffrey R. Akien
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, UK
| | | | - Edward R. T. Tiekink
- Research Centre for Crystalline Materials, Faculty of Science and Technology, Sunway University, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia
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Halcovitch NR, Fryzuk MD. Iminoacyl Alkyl Complexes of Zirconium Supported by a Ferrocene-Linked Diphosphinoamide Ligand Scaffold. Aust J Chem 2016. [DOI: 10.1071/ch15763] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Zirconium dialkyl complexes of the general formula fc(NPiPr2)2ZrR2 (where fc = 1,1′-ferrocenyl, R = CH3, CH2Ph, CH2tBu, tBu) have been synthesized and characterized via the addition of alkyl lithium or potassium benzyl derivatives to the dichloride complex fc(NPiPr2)2ZrCl2(THF). Addition of 2,6-dimethylphenylisocyanide to these alkyl derivatives generates the corresponding mono iminoacyl alkyl zirconium complexes. On thermolysis, the iminoacyl moiety containing a benzyl substituent undergoes rearrangement to yield a new complex that contains an alkene-amido fragment. Mechanistic studies point to a 1,2 hydrogen shift as the rate-determining step.
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Webb MI, Halcovitch NR, Bowes EG, Lee GM, Geier MJ, Vogels CM, O'Neill T, Li H, Flewelling A, Decken A, Gray CA, Westcott SA. Arylspiroborates Derived from 4-tert-Butylcatechol and 3,5-Di-tert-butylcatechol and Their Antimicrobial Activities. J Heterocycl Chem 2013. [DOI: 10.1002/jhet.1997] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Michael I. Webb
- Department of Chemistry and Biochemistry; Mount Allison University; Sackville New Brunswick E4L 1G8 Canada
| | - Nathan R. Halcovitch
- Department of Chemistry and Biochemistry; Mount Allison University; Sackville New Brunswick E4L 1G8 Canada
| | - Eric G. Bowes
- Department of Chemistry and Biochemistry; Mount Allison University; Sackville New Brunswick E4L 1G8 Canada
| | - Graham M. Lee
- Department of Chemistry and Biochemistry; Mount Allison University; Sackville New Brunswick E4L 1G8 Canada
| | - Michael J. Geier
- Department of Chemistry and Biochemistry; Mount Allison University; Sackville New Brunswick E4L 1G8 Canada
| | - Christopher M. Vogels
- Department of Chemistry and Biochemistry; Mount Allison University; Sackville New Brunswick E4L 1G8 Canada
| | - Taryn O'Neill
- Department of Biology; University of New Brunswick; Saint John NB E2L 4L5 Canada
| | - Haoxin Li
- Department of Biology; University of New Brunswick; Saint John NB E2L 4L5 Canada
| | - Andrew Flewelling
- Department of Biology; University of New Brunswick; Saint John NB E2L 4L5 Canada
| | - Andreas Decken
- Department of Chemistry; University of New Brunswick; Fredericton New Brunswick E3B 5A3 Canada
| | - Christopher A. Gray
- Department of Biology; University of New Brunswick; Saint John NB E2L 4L5 Canada
- Department of Chemistry; University of New Brunswick; Fredericton New Brunswick E3B 5A3 Canada
| | - Stephen A. Westcott
- Department of Chemistry and Biochemistry; Mount Allison University; Sackville New Brunswick E4L 1G8 Canada
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Affiliation(s)
- Nathan R. Halcovitch
- Department of Chemistry, The University of British Columbia,
2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
| | - Michael D. Fryzuk
- Department of Chemistry, The University of British Columbia,
2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
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Halcovitch NR, Fryzuk MD. Synthesis and characterization of organo-scandium and yttrium complexes stabilized by phosphinoamide ligands. Dalton Trans 2012; 41:1524-8. [DOI: 10.1039/c1dt11501d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Halcovitch NR, Vogels CM, Decken A, Westcott SA. Synthesis, characterization, and reactivity of a novel thallium arylspiroboronate ester. CAN J CHEM 2009. [DOI: 10.1139/v08-107] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Addition of 3,5-di-tert-butylcatechol (butcat) to solutions of H3B·SMe2 gave the novel diboron species B2(butcat)3 (2) in moderate to high yields. Compound 2 reacts with Tl(acac) to give butcatB(acac) (4) and Tl(Bbutcat2) (5). Attempts to abstract the chlorides from [(dppb)Rh(µ-Cl)]2 (where dppb = 1,4-bis(diphenylphosphino)buthane) using 5 led to the unusual dimer [(dppb)Rh(µ-Cl)2(µ-Tl)Rh(dppb)][Bbutcat2] (6), which contains an unsymmetrical Rh–Tl–Rh bridge.Key words: arylspiroboronate ester, non-coordinating anion, rhodium, thallium.
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