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Silver J, al-Jaff G, Taies JA, Wilson MT, den Engelsen D, Fern GR, Ireland TG. Studies on the binding of CO to low-spin [Fe(II)(Por)L 2] complexes: an aid to understanding the binding of CO to haemoglobin and myoglobin. J Biol Inorg Chem 2023; 28:65-84. [PMID: 36478266 PMCID: PMC9938061 DOI: 10.1007/s00775-022-01969-w] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 10/13/2022] [Indexed: 12/12/2022]
Abstract
The visible and Mössbauer spectra of [Fe(II)(Por)L2] and [Fe(II)(Por)L(CO)] complexes (where Por = protoporphyrin IX (PPIX) or tetra(p-sulfophenyl)porphyrin (TPPS) and L = an aliphatic or aromatic nitrogenous base) are reported and discussed. The results are compared to those of previously reported [Fe(II)(Por)L(CO)] complexes (where Por = PPIX, TPPS, PMXPP, TPP, OMTBP and OEP; L = a nitrogenous aromatic ligand) and HbCO (where Hb = haemoglobin) and MyCO (where My = myoglobin). A new approach, to extracting information from the Mössbauer parameters has been developed by plotting those of the [Fe(II)(Por)L2] complexes against those of [Fe(II)(Por)L(CO)] complexes for the same ligands, has yielded a series of trend lines that show a significant dependence on both the nature of the porphyrin and also of the nitrogenous ligand. Different trend lines were found for aromatic nitrogenous ligands to aliphatic nitrogenous ligands showing that the porphyrins could donate different amounts of charge to the Fe(II) cations as the L ligand changed, and hence, they display electron sink properties. From the plots, it was shown that haemoglobin and myoglobin both bind CO very strongly compared to the model complexes studied herein. Using the reported structural and Mössbauer data for the [Fe(II)(Por)L2] and [Fe(II)(Por)L(CO)] complexes, it proved possible and instructive to plot the Mössbauer parameters against a number of the bond lengths around the Fe(II) cations. The interpretation of the resulting trend lines both supported and facilitated the extension of our findings enabling further understanding of the geometry of the bonding in CO haemoglobin and CO myoglobin.
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Affiliation(s)
- Jack Silver
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
| | - Golzar al-Jaff
- grid.8356.80000 0001 0942 6946School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ Essex UK ,grid.444950.8Department of Chemistry, College of Education, Salahaddin University-Erbil, Erbil, Iraq
| | - Jehad A. Taies
- grid.8356.80000 0001 0942 6946School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ Essex UK ,Department of Chemistry, College of Education for Pure Science, University of Anwar, Ramadi, Iraq
| | - Michael T. Wilson
- grid.8356.80000 0001 0942 6946School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ Essex UK
| | - Daniel den Engelsen
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
| | - George R. Fern
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
| | - Terry G. Ireland
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
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Silver J, Al-Jaff G, Wilson MT, den Engelsen D, Fern GR, Ireland TG. Studies on the binding of nitrogenous bases to protoporphyrin IX iron(II) in aqueous solution at high pH values. J Biol Inorg Chem 2022; 27:297-313. [PMID: 35235042 PMCID: PMC8960585 DOI: 10.1007/s00775-022-01929-4] [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: 11/02/2021] [Accepted: 01/14/2022] [Indexed: 10/28/2022]
Abstract
Studies are reported on the formation of low-spin six-coordinate [Fe(PPIX)L2] complexes from iron(II) protoporphyrin where L is one of a series of nitrogenous ligands (aliphatic, aromatic or heterocyclic). The bonding constants have been determined by titration of the metal complex with these ligands and are compared in relation to previous studies. The adduct formation was monitored utilising optical spectroscopy. In addition, Mӧssbauer spectroscopic experiments were conducted to monitor the electronic environment around the central iron atom in these complexes. The two complementary spectroscopic methods indicated that all nitrogen ligands formed low-spin octahedral complexes. The magnitude of the overall binding constants (β2 values) are discussed and related to (a) the pKa values of the free ligands and (b) the Mössbauer parameter ΔEQ, which represents the quadrupole splitting of the haem iron. The β2 and ΔEQ values are also discussed in terms of the structure of the ligand. Cooperative binding was observed for nearly all the ligands with Hill coefficients close to 2 for iron(II) protoporphyrin; one of these ligands displayed a much greater affinity than any we previously studied, and this was a direct consequence of the structure of the ligand. Overall conclusions on these and previous studies are drawn in terms of aliphatic ligands versus aromatic ring structures and the absence or presence of sterically hindered nitrogen atoms. The implications of the work for the greater understanding of haem proteins in general and in particular how the nitrogenous ligand binding results are relevant to and aid the understanding of the binding of inhibitor molecules to the cytochrome P450 mono-oxygenases (for therapeutic purposes) are also discussed. Changes in the electronic absorption spectra of five-coordinate [Fe(II)(PPIX)(2-MeIm)] that occurred as the temperature was lowered from room temperature to 78° K.
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Affiliation(s)
- Jack Silver
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK
| | - Golzar Al-Jaff
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK.,Department of Chemistry, College of Education, Salahaddin University-Erbil, Erbil, Iraq
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK
| | - Daniel den Engelsen
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK
| | - George R Fern
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK
| | - Terry G Ireland
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK.
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den Engelsen D, Fern GR, Ireland TG, Hudry D, Abeykoon AMM, Nykypanchuk D, Dickerson JH, Silver J. Ultrathin Y 2O 3:Eu 3+nanodiscs: spectroscopic investigations and evidence for reduced concentration quenching. Nanotechnology 2018; 29:455703. [PMID: 30136652 DOI: 10.1088/1361-6528/aadc83] [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] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Here, we report the synthesis and spectral properties of ultrathin nanodiscs (NDs) of Y2O3:Eu3+. It was found that the NDs of Y2O3:Eu3+ with a thickness of about 1 nm can be fabricated in a reproducible, facile and self-assembling process, which does not depend on the Eu3+ concentration. The thickness and morphology of these NDs were determined with small angle x-ray scattering and transmission electron microscopy. We found that the crystal field in these nanoparticles deviates from both the cubic and monoclinic characteristics, albeit the shape of the 5D0 → 7F J (J = 0, 1, 2) transitions shows some similarity with the transitions in the monoclinic material. The Raman spectra of the non-annealed NDs manifest various vibration modes of the oleic acid molecules, which are used to stabilise the NDs. The annealed NDs show two very weak Raman lines, which may be assigned to vibrational modes of Y2O3 NDs. The concentration quenching of the Eu3+ luminescence of the NDs before annealing is largely suppressed and might be explained in terms of a reduction of the phonon density of states.
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Affiliation(s)
- D den Engelsen
- Centre for Phosphor and Display Materials, Wolfson Centre for Materials Processing, Brunel University London, Uxbridge, Middlesex, UB8 3PH, United Kingdom
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Engelsen DD, Fern GR, Ireland TG, Silver J. Cathodoluminescence of Y 2O 3:Ln 3+ (Ln = Tb, Er and Tm) and Y 2O 3:Bi 3+ nanocrystalline particles at 200 keV. RSC Adv 2018. [DOI: 10.1039/c7ra12644a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [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
The cathodoluminescence (CL) spectra of nanocrystalline Y2O3:Tb3+ (0.3%), Y2O3:Er3+ (1%), Y2O3:Tm3+ (2%) and Y2O3:Bi3+ (1%) were recorded in a transmission electron microscope at 200 keV, low current density and various temperatures.
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Affiliation(s)
- Daniel den Engelsen
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - George R. Fern
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Terry G. Ireland
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Jack Silver
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
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Pasberg N, den Engelsen D, Fern GR, Harris PG, Ireland TG, Silver J. Structure and luminescence analyses of simultaneously synthesised (Lu1−xGdx)2O2S:Tb3+ and (Lu1−xGdx)2O3:Tb3+. Dalton Trans 2017; 46:7693-7707. [DOI: 10.1039/c7dt00862g] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoluminescence spectra and simultaneous synthesis of (Lu1−y–xGdx)2O2S:Tby and (Lu1−y–xGdx)2O3:Tby phosphors are reported/discussed along with cathodoluminescence spectra obtained from sub-micron particles.
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Affiliation(s)
- Natalie Pasberg
- Department of Chemical Engineering
- University of Applied Sciences Münster
- D-48565 Steinfurt
- Germany
| | - Daniel den Engelsen
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - George R. Fern
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Paul G. Harris
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Terry G. Ireland
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Jack Silver
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
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Brüninghoff R, Engelsen DD, Fern GR, Ireland TG, Dhillon R, Silver J. Nanosized (Y1−xGdx)2O2S:Tb3+ particles: synthesis, photoluminescence, cathodoluminescence studies and a model for energy transfer in establishing the roles of Tb3+ and Gd3+. RSC Adv 2016. [DOI: 10.1039/c6ra09098b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [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
Herein we describe the synthesis and spectral analysis of nanosized (Y1−xGdx)2O2S:Tb3+ phosphors between x = 0 and x = 1 with 0.1 and 2 mol% Tb3+.
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Affiliation(s)
- Robert Brüninghoff
- Department of Chemical Engineering
- Münster University of Applied Sciences
- Germany
| | - Daniel den Engelsen
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - George R. Fern
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Terry G. Ireland
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Rupinder Dhillon
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
| | - Jack Silver
- Centre for Phosphor and Display Materials
- Wolfson Centre for Materials Processing
- Brunel University London
- Uxbridge
- UK
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Morrison IEG, Samilian A, Coppo P, Ireland TG, Fern GR, Silver J, Withnall R, O’Toole PJ. Multicolour correlative imaging using phosphor probes. J Chem Biol 2015. [DOI: 10.1007/s12154-015-0141-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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den Engelsen D, Harris PG, Ireland TG, Fern GR, Silver J. Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope. Ultramicroscopy 2015; 157:27-34. [PMID: 26021302 DOI: 10.1016/j.ultramic.2015.05.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [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: 01/30/2015] [Revised: 05/05/2015] [Accepted: 05/12/2015] [Indexed: 11/24/2022]
Abstract
Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated.
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Affiliation(s)
- Daniel den Engelsen
- Centre for Phosphor and Display Materials, Wolfson Centre for Materials Processing, Brunel University London, Uxbridge, Middlesex UB8 3PH, UK
| | - Paul G Harris
- Centre for Phosphor and Display Materials, Wolfson Centre for Materials Processing, Brunel University London, Uxbridge, Middlesex UB8 3PH, UK
| | - Terry G Ireland
- Centre for Phosphor and Display Materials, Wolfson Centre for Materials Processing, Brunel University London, Uxbridge, Middlesex UB8 3PH, UK.
| | - George R Fern
- Centre for Phosphor and Display Materials, Wolfson Centre for Materials Processing, Brunel University London, Uxbridge, Middlesex UB8 3PH, UK
| | - Jack Silver
- Centre for Phosphor and Display Materials, Wolfson Centre for Materials Processing, Brunel University London, Uxbridge, Middlesex UB8 3PH, UK
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Silver J, Withnall R, Ireland TG, Fern GR, Zhang S. Light-emitting nanocasts formed from bio-templates: FESEM and cathodoluminescent imaging studies of butterfly scale replicas. Nanotechnology 2008; 19:095302. [PMID: 21817666 DOI: 10.1088/0957-4484/19/9/095302] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nanocasts comprising of red-light-emitting cubic Y(2)O(3):Eu phosphors were made from butterfly wing scale bio-templates. We report herein the first cathodoluminescent images made from such nanocasts and show that valuable insights into the nature of the internal structure of the casts can be gained by the use of this technique. The casts faithfully reproduced the fine sub-micrometre size detail of the scales, as was made evident by both FESEM and cathodoluminescent images that were collected from the same sample areas using a hyphenated FESEM-CL instrument. There was excellent agreement between the FESEM and cathodoluminescent images, the image quality of the latter indicating that the Eu(3+) activator ions were evenly dispersed in the Y(2)O(3):Eu phosphor on a sub-micrometre scale. The casts were made by infilling the natural moulds with a Y(2)O(3):Eu precursor solution that was subsequently dried and fired to convert it into the phosphor material. This method provides a simple, low cost route for fabricating nanostructures having feature dimensions as small as 20 nm in size, and it has the potential to be applied to other metal oxide systems for producing nano-and micro-components for electronic, magnetic or photonic integrated systems.
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Withnall R, Martinez-Rubio MI, Fern GR, Ireland TG, Silver J. Photonic phosphors based on cubic Y2O3:Tb3 infilled into a synthetic opal lattice. ACTA ACUST UNITED AC 2003. [DOI: 10.1088/1464-4258/5/4/359] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Vecht A, Ireland TG. The role of vaterite and aragonite in the formation of pseudo-biogenic carbonate structures: implications for Martian exobiology. Geochim Cosmochim Acta 2000; 64:2719-2725. [PMID: 11543352 DOI: 10.1016/s0016-7037(00)00381-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A simple synthesis of various forms of calcium carbonate with spherical and 'floral' morphologies is reported. Vaterite formation occurs at approximately 25 degrees C, aragonite at approximately 70 degrees C and calcite at about approximately 80 degrees C. These are produced when CO2 is reacted with an aqueous solution of calcium chloride in the presence of ammonia. These conditions may have existed at the surface of Mars in the past, leading us to conclude that such mineral formations may be common there. Although the initial phases are modified over time with changing temperature and pressure conditions, they still influence the final morphology of the carbonates observed. A comparison of these structures with those found in the Martian meteorite ALH84001 suggests, but does not confirm, a non-biogenic origin for the ALH84001 carbonates.
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Affiliation(s)
- A Vecht
- University of Greenwich Centre for Phosphors and Display Materials, London, UK.
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