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Dominant changes in centre Fe atom of decamethyl-ferrocene from ferrocene in methylation. Theor Chem Acc 2023. [DOI: 10.1007/s00214-022-02949-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
AbstractStaggered decamethyl-ferrocene (*Fc) becomes the lower energy conformer at low temperature, whereas the eclipsed conformer of ferrocene (Fc) is more stable. The powerful infrared (IR) spectroscopy which has remarkably provided signatures of ferrocene (Fc) in eclipsed and staggered conformers recently is employed to investigate methylation of Fc. The most significant consequences of the full methylation of Fc in the IR spectra are the blue shift of the band at ~ 800 cm−1 in Fc to ~ 1500 cm−1 in *Fc, and the enhancement of the C–H stretch band at ~ 3200 cm−1 region in *Fc. Further analysis reveals large impact of Fc methylation on core electron energies of the centre Fe atom (1s22s22p63s23p6). The Fe core electron energy changes can be as large as ~ 10 kcal mol−1 and are directional—the Fe 2pz and 3pz orbitals along the *Cp–Fe–*Cp axis (Cp centroids, vertical) change more strongly than other Fe core electrons in px and py orbitals. The directional inner shell energy changes are evidenced by larger inner shell reorganization energy. Energy decomposition analysis (EDA) indicates that methyl groups in *Fc apparently change the physical energy components with respect to Fc. The large steric energy of *Fc evidences that the closest hydrogens on adjacent methyl groups of the same *Cp ring in crystal structure are 0.2–0.4 Å closer than the hydrogens on nearest-neighbour methyl groups on opposing rings in *Fc. A significant increase in Pauli repulsive energy contributes to the large repulsive steric energy in *Fc.
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Wang F, Islam S, Chantler CT. Solvent contribution to ferrocene conformation: Theory and experiment. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Best SP, Streltsov VA, Chantler CT, Li W, Ash PA, Hayama S, Diaz-Moreno S. Redox state and photoreduction control using X-ray spectroelectrochemical techniques - advances in design and fabrication through additive engineering. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:472-479. [PMID: 33650559 DOI: 10.1107/s1600577520016021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
The design and performance of an electrochemical cell and solution flow system optimized for the collection of X-ray absorption spectra from solutions of species sensitive to photodamage is described. A combination of 3D CAD and 3D printing techniques facilitates highly optimized design with low unit cost and short production time. Precise control of the solution flow is critical to both minimizing the volume of solution needed and minimizing the photodamage that occurs during data acquisition. The details of an integrated four-syringe stepper-motor-driven pump and associated software are described. It is shown that combined electrochemical and flow control can allow repeated measurement of a defined volume of solution, 100 µl, of samples sensitive to photoreduction without significant change to the X-ray absorption near-edge structure and is demonstrated by measurements of copper(II) complexes. The flow in situ electrochemical cell allows the collection of high-quality X-ray spectral measurements both in the near-edge region and over an extended energy region as is needed for structural analysis from solution samples. This approach provides control over photodamage at a level at least comparable with that achieved using cryogenic techniques and at the same time eliminates problems associated with interference due to Bragg peaks.
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Affiliation(s)
- Stephen Peter Best
- School of Chemistry, The University of Melbourne, Parkville, Melbourne, Victoria 3010, Australia
| | - Victor A Streltsov
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | | | - Wangzhe Li
- Department of Chemistry, University of Oxford, Oxford OX1 3QR, United Kingdom
| | - Philip A Ash
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom
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DeSimone MA, Ilagan MRQ, Pike RD, Herber RH, Watson EJ. Syntheses, structures and mössbauer effect spectroscopy of triple-decker complexes incorporating decamethylferrocene. J Organomet Chem 2020. [DOI: 10.1016/j.jorganchem.2020.121339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Allison M, Wilson D, Pask CM, McGowan PC, Lord RM. β-Diketonate versus β-Ketoiminate: The Importance of a Ferrocenyl Moiety in Improving the Anticancer Potency. Chembiochem 2020; 21:1988-1996. [PMID: 32176811 PMCID: PMC7496474 DOI: 10.1002/cbic.202000028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/23/2020] [Indexed: 12/01/2022]
Abstract
Herein we present a library of fully characterized β-diketonate and β-ketoiminate compounds that are functionalized with a ferrocenyl moiety. Their cytotoxic potential has been determined by screening against human breast adenocarcinomas (MCF-7 and MDA-MB-231), human colorectal carcinoma p53 wild type (HCT116 p53+/+ ) and normal human prostate (PNT2) cell lines. The ferrocenyl β-diketonate compounds are more than 18 times more cytotoxic than the ferrocenyl β-ketoiminate analogues. Against MCF-7, compounds functionalized at the meta position are up to nine times more cytotoxic than when functionalized at the para position. The ferrocenyl β-diketonate compounds have increased selectivity towards MCF-7 and MDA-MB-231, with several complexes having selectivity index (SI) values that are more than nine times (MCF-7) and more than six times (MDA-MB-231) that of carboplatin. The stability of these compounds in dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) has been assessed by NMR spectroscopy and mass spectrometry studies, and the compounds show no oxidation of the iron center from FeII to FeIII . Cytotoxicity screening was performed in both DMSO and DMF, with no significant differences observedin their potency.
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Affiliation(s)
| | - Daniel Wilson
- School of ChemistryUniversity of LeedsLeedsLS2 9JTUK
| | | | | | - Rianne M. Lord
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
- School of Chemistry and BiosciencesUniversity of BradfordBradfordBD7 1DPUK
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Trevorah R, Tran N, Appadoo D, Wang F, Chantler C. Resolution of ferrocene and deuterated ferrocene conformations using dynamic vibrational spectroscopy: Experiment and theory. Inorganica Chim Acta 2020. [DOI: 10.1016/j.ica.2020.119491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Trevorah RM, Chantler CT, Schalken MJ. New Features Observed in Self-Absorption-Corrected X-ray Fluorescence Spectra for Ni Complexes with Uncertainties. J Phys Chem A 2020; 124:1634-1647. [PMID: 31995382 DOI: 10.1021/acs.jpca.9b10619] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a new technology for analyzing the molecular structure and in particular subtle conformational differences in Ni complexes using X-ray absorption spectroscopy (XAS), enabling tighter and more robust constraints of structure and dynamic bond lengths. Self-absorption and attenuating effects have a large impact in fluorescence X-ray absorption spectroscopy (XAS), compromising accuracy and insight in structural and advanced analyses. We correct for these dominant systematic effects. We investigate nickel(II) complexes, that is, bis(N-n-propyl-salicylaldiminato) nickel(II), "n-pr", and bis(N-i-propyl-salicylaldiminato) nickel(II), "i-pr", in 15 mM solutions with 0.1% w/w Ni. One is "square-planar" and one is "tetrahedral", with identical coordination numbers. We identify two key sources of uncertainty and provide robust estimates for them, reflecting the quality of the data, and provide meaningful estimates of χr2 suitable for hypothesis testing. We apply significance and model testing for fluorescence data, with direct uncertainty estimates. Two new peaks are revealed in the X-ray absorption fine structure (XAFS) at k ≈ 4.4 and 5.4 Å-1. The high intrinsic accuracy of our processed data allows these features to be well modeled and yields deeper potential insight. Three important notions in the field are addressed: resolvability of shell radii, estimation of the number of independent data points in least-squares or Bayesian analysis, and the effect of uncertainties on the determined structure and the determinability of key structural parameters. Conventional XAFS fitting requires a kmin and a kmax. The origin of these limits is explained from the data, in a quantitative manner. Being able to distinguish the isomers spectroscopically and structurally places strong demands on the data, the uncertainties, and the model interpretation, and this article reports success in this subtle structural identification. Two nearby shells-the innermost two shells-are identified quantitatively, well below the conventional aliasing limit. This illustrates the application of new technology to gain new insight.
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Affiliation(s)
- Ryan M Trevorah
- School of Physics , University of Melbourne , Parkville , VIC 3010 , Australia
| | | | - Martin J Schalken
- School of Physics , University of Melbourne , Parkville , VIC 3010 , Australia
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Chantler CT, Bourke JD. Low-energy electron properties: Electron inelastic mean free path, energy loss function and the dielectric function. Recent measurements, applications, and the plasmon-coupling theory. Ultramicroscopy 2019; 201:38-48. [PMID: 30925298 DOI: 10.1016/j.ultramic.2019.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/21/2019] [Indexed: 11/30/2022]
Abstract
We review new self-consistent models of inelastic electron scattering in condensed matter systems for accurate calculations of low-energy electron inelastic mean free paths (IMFPs) for XAFS and low energy diffraction. The accuracy of theoretical determinations of the electron IMFP at low energies is one of the key limiting factors in current XAFS modeling and Monte Carlo transport. Recent breakthroughs in XAFS analysis show that there exist significant discrepancies between theoretical and experimental IMFP values, and that this can significantly impact upon extraction of other key structural parameters from both XANES and XAFS. Resolution of these discrepancies is required to validate experimental studies of material structures, and is particularly relevant to the characterization of small molecules and organometallic systems for which tabulated electron scattering data is often sparse or highly uncertain. Novel models implement plasmon coupling mechanisms for the first time, in addition to causally-constrained lifetime broadening and high-precision density functional theory, and enables dramatic improvements in the agreement with recent high profile IMFP measurements. We discuss a theoretical approach for IMFP determination linking the optical dielectric function and energy loss spectrum of a material with its electron scattering properties and characteristic plasmon excitations. We review models inclusive of plasmon coupling, allowing us to move beyond the longstanding statistical approximation and explicitly demonstrate the effects of band structure on the detailed behaviour of bulk electron excitations in a solid or small molecule. This interrogates the optical response of the material, which we obtain using density functional theory. We find that new developments dramatically improve agreement with experimental electron scattering results in the low-energy region (30 eV → 200 eV) where plasmon excitations are dominant. Corresponding improvements are therefore made in Low Energy Electron Transport, LEEM, theoretical XAFS spectra and detector modelling.
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Affiliation(s)
- C T Chantler
- School of Physics, University of Melbourne, Parkville, Vic, 3010 Australia.
| | - J D Bourke
- School of Physics, University of Melbourne, Parkville, Vic, 3010 Australia
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Tazi M, Erb W, Halauko YS, Ivashkevich OA, Matulis VE, Roisnel T, Dorcet V, Mongin F. From 2- to 3-Substituted Ferrocene Carboxamides or How to Apply Halogen “Dance” to the Ferrocene Series. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00659] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Mehdi Tazi
- Equipe
Chimie Organique et Interfaces, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10A, Case
1003, Campus Scientifique de Beaulieu, 35042 Cedex Rennes, France
| | - William Erb
- Equipe
Chimie Organique et Interfaces, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10A, Case
1003, Campus Scientifique de Beaulieu, 35042 Cedex Rennes, France
| | - Yury S. Halauko
- UNESCO
Chair of Belarusian State University, 14 Leningradskaya Str., Minsk 220030, Belarus
| | - Oleg A. Ivashkevich
- UNESCO
Chair of Belarusian State University, 14 Leningradskaya Str., Minsk 220030, Belarus
| | - Vadim E. Matulis
- Research
Institute for Physico-Chemical Problems of Belarusian State University, 14 Leningradskaya Str., Minsk 220030, Belarus
| | - Thierry Roisnel
- Centre
de Diffractométrie X, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10B, Campus de Beaulieu, 35042 Cedex Rennes, France
| | - Vincent Dorcet
- Centre
de Diffractométrie X, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10B, Campus de Beaulieu, 35042 Cedex Rennes, France
| | - Florence Mongin
- Equipe
Chimie Organique et Interfaces, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, Bâtiment 10A, Case
1003, Campus Scientifique de Beaulieu, 35042 Cedex Rennes, France
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Best SP, Wang F, Islam MT, Islam S, Appadoo D, Trevorah RM, Chantler CT. Reinterpretation of Dynamic Vibrational Spectroscopy to Determine the Molecular Structure and Dynamics of Ferrocene. Chemistry 2016; 22:18019-18026. [PMID: 27734528 DOI: 10.1002/chem.201603823] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Indexed: 11/10/2022]
Abstract
Molecular distortion of dynamic molecules gives a clear signature in the vibrational spectra, which can be modeled to give estimates of the energy barrier and the sensitivity of the frequencies of the vibrational modes to the reaction coordinate. The reaction coordinate method (RCM) utilizes ab initio-calculated spectra of the molecule in its ground and transition states together with their relative energies to predict the temperature dependence of the vibrational spectra. DFT-calculated spectra of the eclipsed (D5h ) and staggered (D5d ) forms of ferrocene (Fc), and its deuterated analogue, within RCM explain the IR spectra of Fc in gas (350 K), solution (300 K), solid solution (7-300 K), and solid (7-300 K) states. In each case the D5h rotamer is lowest in energy but with the barrier to interconversion between rotamers higher for solution-phase samples (ca. 6 kJ mol-1 ) than for the gas-phase species (1-3 kJ mol-1 ). The generality of the approach is demonstrated with application to tricarbonyl(η4 -norbornadiene)iron(0), Fe(NBD)(CO)3 . The temperature-dependent coalescence of the ν(CO) bands of Fe(NBD)(CO)3 is well explained by the RCM without recourse to NMR-like rapid exchange. The RCM establishes a clear link between the calculated ground and transition states of dynamic molecules and the temperature-dependence of their vibrational spectra.
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Affiliation(s)
- Stephen P Best
- School of Chemistry, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Feng Wang
- Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Melbourne, Victoria, 3122, Australia
| | - M Tauhidul Islam
- School of Chemistry, University of Melbourne, Parkville, Victoria, 3010, Australia.,School of Physics, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Shawkat Islam
- Department of Chemistry and Biotechnology, Swinburne University of Technology, Hawthorn, Melbourne, Victoria, 3122, Australia
| | - Dominique Appadoo
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, 3168, Australia
| | - Ryan M Trevorah
- School of Physics, University of Melbourne, Parkville, Victoria, 3010, Australia
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