Experimental and time-dependent density functional theory characterization of the UV−Visible spectra of monomeric and μ‑Oxo dimeric ferriprotoporphyrin IX
| dc.contributor.author | Kuter, David | |
| dc.contributor.author | Venter, Gerhard A | |
| dc.contributor.author | Naidoo, Kevin J | |
| dc.contributor.author | Egan, Timothy J | |
| dc.date.accessioned | 2016-08-23T12:15:20Z | |
| dc.date.available | 2016-08-23T12:15:20Z | |
| dc.date.issued | 2012 | |
| dc.date.updated | 2016-08-23T12:13:39Z | |
| dc.description.abstract | Speciation of ferriprotoporphyrin IX, Fe(III)PPIX, in aqueous solution is complex. Despite the use of its characteristic spectroscopic features for identification, the theoretical basis of the unique UV−visible absorbance spectrum of μ- [Fe(III)PPIX]2O has not been explored. To investigate this and to establish a structural and spectroscopic model for Fe(III)PPIX species, density functional theory (DFT) calculations were undertaken for H2O−Fe(III)PPIX and μ- [Fe(III)PPIX]2O. The models agreed with related Fe(III)porphyrin crystal structures and reproduced vibrational spectra well. The UV−visible absorbance spectra of H2O−Fe(III)PPIX and μ-[Fe(III)PPIX]2O were calculated using time-dependent DFT and reproduced major features of the experimental spectra of both. Transitions contributing to calculated excitations have been identified. The features of the electronic spectrum calculated for μ-[Fe(III)PPIX]2O were attributed to delocalization of electron density between the two porphyrin rings of the dimer, the weaker ligand field of the axial ligand, and antiferromagnetic coupling of the Fe(III) centers. Room temperature magnetic circular dichroism (MCD) spectra have been recorded and are shown to be useful in distinguishing between these two Fe(III)PPIX species. Bands underlying major spectroscopic features were identified through simultaneous deconvolution of UV−visible and MCD spectra. Computed UV−visible spectra were compared to deconvoluted spectra. Interpretation of the prominent bands of H2O−Fe(III)PPIX largely conforms to previous literature. Owing to the weak paramagnetism of μ-[Fe(III)PPIX]2O at room temperature and the larger number of underlying excitations, interpretation of its experimental UV−visible spectrum was necessarily tentative. Nonetheless, comparison with the calculated spectra of antiferromagnetically coupled and paramagnetic forms of the μ-oxo dimer of Fe(III)porphine suggested that the composition of the Soret band involves a mixture of π→π* and π→dπ charge transfer transitions. The Q-band and charge transfer bands appear to amalgamate into a mixed low energy envelope consisting of excitations with heavily admixed π→π* and charge transfer transitions. | en_ZA |
| dc.identifier | http://dx.doi.org/http://pubs.acs.org/doi/abs/10.1021/ic301154e | |
| dc.identifier.apacitation | Kuter, D., Venter, G. A., Naidoo, K. J., & Egan, T. J. (2012). Experimental and time-dependent density functional theory characterization of the UV−Visible spectra of monomeric and μ‑Oxo dimeric ferriprotoporphyrin IX. <i>Inorganic Chemistry.</i>, http://hdl.handle.net/11427/21464 | en_ZA |
| dc.identifier.chicagocitation | Kuter, David, Gerhard A Venter, Kevin J Naidoo, and Timothy J Egan "Experimental and time-dependent density functional theory characterization of the UV−Visible spectra of monomeric and μ‑Oxo dimeric ferriprotoporphyrin IX." <i>Inorganic Chemistry.</i> (2012) http://hdl.handle.net/11427/21464 | en_ZA |
| dc.identifier.citation | Kuter, D., Venter, G. A., Naidoo, K. J., & Egan, T. J. (2012). Experimental and Time-Dependent Density Functional Theory Characterization of the UV–Visible Spectra of Monomeric and μ-Oxo Dimeric Ferriprotoporphyrin IX. Inorganic chemistry, 51(19), 10233-10250. | en_ZA |
| dc.identifier.issn | 0020-1669 | en_ZA |
| dc.identifier.ris | TY - Journal Article AU - Kuter, David AU - Venter, Gerhard A AU - Naidoo, Kevin J AU - Egan, Timothy J AB - Speciation of ferriprotoporphyrin IX, Fe(III)PPIX, in aqueous solution is complex. Despite the use of its characteristic spectroscopic features for identification, the theoretical basis of the unique UV−visible absorbance spectrum of μ- [Fe(III)PPIX]2O has not been explored. To investigate this and to establish a structural and spectroscopic model for Fe(III)PPIX species, density functional theory (DFT) calculations were undertaken for H2O−Fe(III)PPIX and μ- [Fe(III)PPIX]2O. The models agreed with related Fe(III)porphyrin crystal structures and reproduced vibrational spectra well. The UV−visible absorbance spectra of H2O−Fe(III)PPIX and μ-[Fe(III)PPIX]2O were calculated using time-dependent DFT and reproduced major features of the experimental spectra of both. Transitions contributing to calculated excitations have been identified. The features of the electronic spectrum calculated for μ-[Fe(III)PPIX]2O were attributed to delocalization of electron density between the two porphyrin rings of the dimer, the weaker ligand field of the axial ligand, and antiferromagnetic coupling of the Fe(III) centers. Room temperature magnetic circular dichroism (MCD) spectra have been recorded and are shown to be useful in distinguishing between these two Fe(III)PPIX species. Bands underlying major spectroscopic features were identified through simultaneous deconvolution of UV−visible and MCD spectra. Computed UV−visible spectra were compared to deconvoluted spectra. Interpretation of the prominent bands of H2O−Fe(III)PPIX largely conforms to previous literature. Owing to the weak paramagnetism of μ-[Fe(III)PPIX]2O at room temperature and the larger number of underlying excitations, interpretation of its experimental UV−visible spectrum was necessarily tentative. Nonetheless, comparison with the calculated spectra of antiferromagnetically coupled and paramagnetic forms of the μ-oxo dimer of Fe(III)porphine suggested that the composition of the Soret band involves a mixture of π→π* and π→dπ charge transfer transitions. The Q-band and charge transfer bands appear to amalgamate into a mixed low energy envelope consisting of excitations with heavily admixed π→π* and charge transfer transitions. DA - 2012 DB - OpenUCT DP - University of Cape Town J1 - Inorganic Chemistry. LK - https://open.uct.ac.za PB - University of Cape Town PY - 2012 SM - 0020-1669 T1 - Experimental and time-dependent density functional theory characterization of the UV−Visible spectra of monomeric and μ‑Oxo dimeric ferriprotoporphyrin IX TI - Experimental and time-dependent density functional theory characterization of the UV−Visible spectra of monomeric and μ‑Oxo dimeric ferriprotoporphyrin IX UR - http://hdl.handle.net/11427/21464 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/21464 | |
| dc.identifier.uri | http://pubs.acs.org/doi/abs/10.1021/ic301154e | |
| dc.identifier.vancouvercitation | Kuter D, Venter GA, Naidoo KJ, Egan TJ. Experimental and time-dependent density functional theory characterization of the UV−Visible spectra of monomeric and μ‑Oxo dimeric ferriprotoporphyrin IX. Inorganic Chemistry.. 2012; http://hdl.handle.net/11427/21464. | en_ZA |
| dc.language | eng | en_ZA |
| dc.publisher | American Chemical Society | en_ZA |
| dc.publisher.institution | University of Cape Town | |
| dc.source | Inorganic Chemistry. | en_ZA |
| dc.source.uri | http://pubs.acs.org/journal/inocaj/about.html | |
| dc.subject.other | μ‑Oxo dimeric ferriprotoporphyrin IX | |
| dc.subject.other | UV−Visible spectra | |
| dc.subject.other | density functional theory | |
| dc.title | Experimental and time-dependent density functional theory characterization of the UV−Visible spectra of monomeric and μ‑Oxo dimeric ferriprotoporphyrin IX | en_ZA |
| dc.type | Journal Article | en_ZA |
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Article | en_ZA |