Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide.
Three synthetic analogues of westiallamide, HL, have previously been synthesized (HL) that have a common backbone (derived from l-valine) with HL but differ in their heterocyclic rings (imidazole, oxazole, thiazole, and oxazoline). Herein we explore in detail through high-resolution pulsed electron...
Published in: | Inorganic Chemistry |
---|---|
Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Chemical Society
2014
|
Subjects: | |
Online Access: | https://espace.library.uq.edu.au/view/UQ:345495/UQ345495_postprint.pdf https://espace.library.uq.edu.au/view/UQ:345495 |
id |
ftunivqespace:oai:espace.library.uq.edu.au:UQ:345495 |
---|---|
record_format |
openpolar |
spelling |
ftunivqespace:oai:espace.library.uq.edu.au:UQ:345495 2023-05-15T17:54:03+02:00 Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide. Comba, Peter Dovalil, Nina Hanson, Graeme R. Harmer, Jeffrey R. Noble, Christopher J. Riley, Mark J. Seibold, Bjoern 2014-11-13 https://espace.library.uq.edu.au/view/UQ:345495/UQ345495_postprint.pdf https://espace.library.uq.edu.au/view/UQ:345495 eng eng American Chemical Society doi:10.1021/ic5014413 issn:0020-1669 issn:1520-510X orcid:0000-0003-0306-4360 orcid:0000-0003-4583-2401 orcid:0000-0002-1936-8767 Not set FT120100421 Chemistry Inorganic & Nuclear 1604 Inorganic Chemistry 1606 Physical and Theoretical Chemistry Journal Article 2014 ftunivqespace https://doi.org/10.1021/ic5014413 2020-12-15T02:20:51Z Three synthetic analogues of westiallamide, HL, have previously been synthesized (HL) that have a common backbone (derived from l-valine) with HL but differ in their heterocyclic rings (imidazole, oxazole, thiazole, and oxazoline). Herein we explore in detail through high-resolution pulsed electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectroscopy in conjunction with density functional theory (DFT) the geometric and electronic structures of the mono- and dinuclear Cu complexes of these cyclic pseudo hexapeptides. Orientation-selective hyperfine sublevel correlation, electron nuclear double resonance, and three-pulse electron spin echo envelope modulation spectroscopy of [Cu(HL)(MeOH)] reveal delocalization of the unpaired electron spin onto the ligating and distal nitrogens of the coordinated heterocyclic rings and that they are magnetically inequivalent. DFT calculations confirm this and show similar spin densities on the distal heteroatoms in the heterocyclic rings coordinated to the Cu ion in the other cyclic pseudo hexapeptide [Cu(HL)(MeOH)] complexes. The magnetic inequivalencies in [Cu(HL)(MeOH)] arise from different orientations of the heterocyclic rings coordinated to the Cu ion, and the delocalization of the unpaired electron onto the distal heteroatoms within these N-methylimidazole rings depends upon their location with respect to the Cu dx-y orbital. A systematic study of DFT functionals and basis sets was undertaken to examine the ability to reproduce the experimentally determined spin Hamiltonian parameters. Inclusion of spin-orbit coupling (SOC) using MAG-ReSpect or ORCA with a BHLYP/IGLO-II Wachters setup with SOC corrections and ∼38% Hartree-Fock exchange gave the best predictions of the g and A(Cu) matrices. DFT calculations of the N hyperfine and quadrupole parameters for the distal nitrogens of the coordinated heterocyclic rings in [Cu(HL)(MeOH)] with the B1LYP functional and the SVP basis set were in excellent agreement with the experimental data, though other choices of functional and basis set also provided reasonable values. MCD, EPR, mass spectrometry, and DFT showed that preparation of the dinuclear Cu complex in a 1:1 MeOH/glycerol mixture (necessary for MCD) resulted in the exchange of the bridging methoxide ligand for glycerol with a corresponding decrease in the magnitude of the exchange coupling. Article in Journal/Newspaper Orca The University of Queensland: UQ eSpace Hartree ENVELOPE(-44.716,-44.716,-60.783,-60.783) Inorganic Chemistry 53 23 12323 12336 |
institution |
Open Polar |
collection |
The University of Queensland: UQ eSpace |
op_collection_id |
ftunivqespace |
language |
English |
topic |
Chemistry Inorganic & Nuclear 1604 Inorganic Chemistry 1606 Physical and Theoretical Chemistry |
spellingShingle |
Chemistry Inorganic & Nuclear 1604 Inorganic Chemistry 1606 Physical and Theoretical Chemistry Comba, Peter Dovalil, Nina Hanson, Graeme R. Harmer, Jeffrey R. Noble, Christopher J. Riley, Mark J. Seibold, Bjoern Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide. |
topic_facet |
Chemistry Inorganic & Nuclear 1604 Inorganic Chemistry 1606 Physical and Theoretical Chemistry |
description |
Three synthetic analogues of westiallamide, HL, have previously been synthesized (HL) that have a common backbone (derived from l-valine) with HL but differ in their heterocyclic rings (imidazole, oxazole, thiazole, and oxazoline). Herein we explore in detail through high-resolution pulsed electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectroscopy in conjunction with density functional theory (DFT) the geometric and electronic structures of the mono- and dinuclear Cu complexes of these cyclic pseudo hexapeptides. Orientation-selective hyperfine sublevel correlation, electron nuclear double resonance, and three-pulse electron spin echo envelope modulation spectroscopy of [Cu(HL)(MeOH)] reveal delocalization of the unpaired electron spin onto the ligating and distal nitrogens of the coordinated heterocyclic rings and that they are magnetically inequivalent. DFT calculations confirm this and show similar spin densities on the distal heteroatoms in the heterocyclic rings coordinated to the Cu ion in the other cyclic pseudo hexapeptide [Cu(HL)(MeOH)] complexes. The magnetic inequivalencies in [Cu(HL)(MeOH)] arise from different orientations of the heterocyclic rings coordinated to the Cu ion, and the delocalization of the unpaired electron onto the distal heteroatoms within these N-methylimidazole rings depends upon their location with respect to the Cu dx-y orbital. A systematic study of DFT functionals and basis sets was undertaken to examine the ability to reproduce the experimentally determined spin Hamiltonian parameters. Inclusion of spin-orbit coupling (SOC) using MAG-ReSpect or ORCA with a BHLYP/IGLO-II Wachters setup with SOC corrections and ∼38% Hartree-Fock exchange gave the best predictions of the g and A(Cu) matrices. DFT calculations of the N hyperfine and quadrupole parameters for the distal nitrogens of the coordinated heterocyclic rings in [Cu(HL)(MeOH)] with the B1LYP functional and the SVP basis set were in excellent agreement with the experimental data, though other choices of functional and basis set also provided reasonable values. MCD, EPR, mass spectrometry, and DFT showed that preparation of the dinuclear Cu complex in a 1:1 MeOH/glycerol mixture (necessary for MCD) resulted in the exchange of the bridging methoxide ligand for glycerol with a corresponding decrease in the magnitude of the exchange coupling. |
format |
Article in Journal/Newspaper |
author |
Comba, Peter Dovalil, Nina Hanson, Graeme R. Harmer, Jeffrey R. Noble, Christopher J. Riley, Mark J. Seibold, Bjoern |
author_facet |
Comba, Peter Dovalil, Nina Hanson, Graeme R. Harmer, Jeffrey R. Noble, Christopher J. Riley, Mark J. Seibold, Bjoern |
author_sort |
Comba, Peter |
title |
Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide. |
title_short |
Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide. |
title_full |
Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide. |
title_fullStr |
Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide. |
title_full_unstemmed |
Insights into the Electronic Structure of CuII Bound to an Imidazole Analogue of Westiellamide. |
title_sort |
insights into the electronic structure of cuii bound to an imidazole analogue of westiellamide. |
publisher |
American Chemical Society |
publishDate |
2014 |
url |
https://espace.library.uq.edu.au/view/UQ:345495/UQ345495_postprint.pdf https://espace.library.uq.edu.au/view/UQ:345495 |
long_lat |
ENVELOPE(-44.716,-44.716,-60.783,-60.783) |
geographic |
Hartree |
geographic_facet |
Hartree |
genre |
Orca |
genre_facet |
Orca |
op_relation |
doi:10.1021/ic5014413 issn:0020-1669 issn:1520-510X orcid:0000-0003-0306-4360 orcid:0000-0003-4583-2401 orcid:0000-0002-1936-8767 Not set FT120100421 |
op_doi |
https://doi.org/10.1021/ic5014413 |
container_title |
Inorganic Chemistry |
container_volume |
53 |
container_issue |
23 |
container_start_page |
12323 |
op_container_end_page |
12336 |
_version_ |
1766161770973495296 |