1
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Interactions of N-hydroxyamphetamine with an iron porphyrin: A unique intramolecular H-bond probed by DFT calculations. J Inorg Biochem 2022; 231:111779. [DOI: 10.1016/j.jinorgbio.2022.111779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/03/2022] [Accepted: 02/22/2022] [Indexed: 11/18/2022]
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2
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Abucayon EG, Chu JM, Ayala M, Khade RL, Zhang Y, Richter-Addo GB. Insight into the preferential N-binding versus O-binding of nitrosoarenes to ferrous and ferric heme centers. Dalton Trans 2021; 50:3487-3498. [PMID: 33634802 PMCID: PMC8061117 DOI: 10.1039/d0dt03604h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nitrosoarenes (ArNOs) are toxic metabolic intermediates that bind to heme proteins to inhibit their functions. Although much of their biological functions involve coordination to the Fe centers of hemes, the factors that determine N-binding or O-binding of these ArNOs have not been determined. We utilize X-ray crystallography and density functional theory (DFT) analyses of new representative ferrous and ferric ArNO compounds to provide the first theoretical insight into preferential N-binding versus O-binding of ArNOs to hemes. Our X-ray structural results favored N-binding of ArNO to ferrous heme centers, and O-binding to ferric hemes. Results of the DFT calculations rationalize this preferential binding on the basis of the energies of associated spin-states, and reveal that the dominant stabilization forces in the observed ferrous N-coordination and ferric O-coordination are dπ-pπ* and dσ-pπ*, respectively. Our results provide, for the first time, an explanation why in situ oxidation of the ferrous-ArNO compound to its ferric state results in the observed subsequent dissociation of the ligand.
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Affiliation(s)
- Erwin G Abucayon
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
| | - Jia-Min Chu
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, USA.
| | - Megan Ayala
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
| | - Rahul L Khade
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, USA.
| | - Yong Zhang
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, USA.
| | - George B Richter-Addo
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
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3
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Ji J, Chung Y, Hyun K, Chung KY, Kwon Y. Effect of axial ligand on the performance of hemin based catalysts and their use for fuel cells. J IND ENG CHEM 2020. [DOI: 10.1016/j.jiec.2020.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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4
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Dhifaoui S, Mchiri C, Quatremare P, Marvaud V, Bujacz A, Nasri H. Molecular structure, magnetic properties, cyclic voltammetry of the low-spin iron(III) Bis(4-ethylaniline) complex with the para -chloro substituted meso -tetraphenylporphyrin. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2017.10.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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5
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Nasri S, Brahmi J, Turowska-Tyrk I, Schulz CE, Nasri H. Synthesis, UV-visible and Mössbauer spectroscopic studies and molecular structure of the low-spin iron(II) Bis( tert -butyl isocyanide)(5, 10, 15, 20-[4-(benzoyloxy)phenyl]porphyrin) coordination compound. J Organomet Chem 2017. [DOI: 10.1016/j.jorganchem.2017.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Olafson KN, Nguyen TQ, Vekilov PG, Rimer JD. Deconstructing Quinoline-Class Antimalarials to Identify Fundamental Physicochemical Properties of Beta-Hematin Crystal Growth Inhibitors. Chemistry 2017; 23:13638-13647. [PMID: 28833627 DOI: 10.1002/chem.201702251] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Indexed: 11/12/2022]
Abstract
A versatile approach to control crystallization involves the use of modifiers, which are additives that interact with crystal surfaces and alter their growth rates. Elucidating a modifier's binding specificity to anisotropic crystal surfaces is a ubiquitous challenge that is critical to their design. In this study, we select hematin, a byproduct of malaria parasites, as a model system to examine the complementarity of modifiers (i.e., antimalarial drugs) to β-hematin crystal surfaces. We divide two antimalarials, chloroquine and amodiaquine, into segments consisting of a quinoline base, common to both drugs, and side chains that differentiate their modes of action. Using a combination of scanning probe microscopy, bulk crystallization, and analytical techniques, we show that the base and side chain work synergistically to reduce the rate of hematin crystallization. In contrast to general observations that modifiers retain their function upon segmentation, we show that the constituents do not act as modifiers. A systematic study of quinoline isomers and analogues shows how subtle rearrangement and removal of functional moieties can create effective constituents from previously ineffective modifiers, along with tuning their inhibitory modes of action. These findings highlight the importance of specific functional moieties in drug compounds, leading to an improved understanding of modifier-crystal interactions that could prove to be applicable to the design of new antimalarials.
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Affiliation(s)
- Katy N Olafson
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA
| | - Tam Q Nguyen
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA
| | - Peter G Vekilov
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA.,Department of Chemistry, University of Houston, 3585 Cullen Boulevard, Houston, TX 77204, USA
| | - Jeffrey D Rimer
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA.,Department of Chemistry, University of Houston, 3585 Cullen Boulevard, Houston, TX 77204, USA
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7
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Watanabe A, Takakusa H, Kimura T, Inoue SI, Kusuhara H, Ando O. Analysis of Mechanism-Based Inhibition of CYP 3A4 by a Series of Fluoroquinolone Antibacterial Agents. Drug Metab Dispos 2016; 44:1608-16. [DOI: 10.1124/dmd.116.071654] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 07/27/2016] [Indexed: 11/22/2022] Open
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8
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Ben Haj Hassen L, Ezzayani K, Rousselin Y, Stern C, Nasri H, Schulz CE. Synthesis, UV/vis, FT-IR and Mössbauer spectroscopic characterization and molecular structure of the Bis[4-(2-aminoethyl)morpholine](tetrakis(4-metoxyphenyl)porphyrinato) iron(II) complex. J Mol Struct 2016. [DOI: 10.1016/j.molstruc.2016.01.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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9
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Dhifaoui S, Harhouri W, Bujacz A, Nasri H. Crystal structure of bis-(benzyl-amine-κN)[5,10,15,20-tetra-kis-(4-chloro-phen-yl)porphyrinato-κ(4) N]iron(II) n-hexane monosolvate. Acta Crystallogr E Crystallogr Commun 2016; 72:102-5. [PMID: 26870596 PMCID: PMC4704743 DOI: 10.1107/s2056989015024135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 12/15/2015] [Indexed: 11/10/2022]
Abstract
In the title compound, [Fe(II)(C44H24Cl4N4)(C6H5CH2NH2)2]·C6H14 or [Fe(II)(TPP-Cl)(BzNH2)2]·n-hexane [where TPP-Cl and BzNH2 are 5,10,15,20-tetra-kis-(4-chloro-phen-yl)porphyrinate and benzyl-amine ligands, respectively], the Fe(II) cation lies on an inversion centre and is octa-hedrally coordinated by the four pyrrole N atoms of the porphyrin ligand in the equatorial plane and by two amine N atoms of the benzyl-amine ligand in the axial sites. The crystal structure also contains one inversion-symmetric n-hexane solvent mol-ecule per complex mol-ecule. The average Fe-Npyrrole bond length [1.994 (3) Å] indicates a low-spin complex. The crystal packing is sustained by N-H⋯Cl and C-H⋯Cl hydrogen-bonding inter-actions and by C-H⋯π inter-molecular inter-actions, leading to a three-dimensional network structure.
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Affiliation(s)
- Selma Dhifaoui
- Laboratoire de Physico-chimie des Matériaux, Faculté des Sciences de Monastir, Avenue de l’environnement, 5019 Monastir, University of Monastir, Tunisia
| | - Wafa Harhouri
- Laboratoire de Physico-chimie des Matériaux, Faculté des Sciences de Monastir, Avenue de l’environnement, 5019 Monastir, University of Monastir, Tunisia
| | - Anna Bujacz
- X-Ray Analysis Laboratory, Institute of Technical Biochemistry, Lodz University of Technology, Stefanowskiego 4/10, 90-924 Lodz, Poland
| | - Habib Nasri
- Laboratoire de Physico-chimie des Matériaux, Faculté des Sciences de Monastir, Avenue de l’environnement, 5019 Monastir, University of Monastir, Tunisia
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10
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McQuarters AB, Goodrich LE, Goodrich CM, Lehnert N. Disproportionation of O-Benzylhydroxylamine Catalyzed by a Ferric Bis-Picket Fence Porphyrin Complex. Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201300125] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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11
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Munro OQ, Pearson N. Hydrogen bonding and crystal packing favor a nonplanarCo(III)porphyrin conformation and unusually weak axial ligation in [Co(TPP)(benzylamine)2](SCN): A crystallographic and density functional theory investigation. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424604000441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The single crystal X-ray structure of [ Co ( TPP )( BzNH2)2]( SCN ), compound 2, where TPP = 5,10,15,20-tetraphenylporphyrin dianion and BzNH2= benzylamine, reveals that the SCN-ion is hydrogen-bonded to one of the coordinated amino group hydrogen atoms via its sulfur atom. Furthermore, the N – H ⋯ SCN interaction is balanced by a stronger N – H ⋯ NCS hydrogen bonding interaction for the trans BzNH2ligand as a result of the multiple hydrogen bond accepting character of the thiocyanate ion. Analysis of the crystal packing shows that these two hydrogen bonds play a major role in fixing unusual orientations for the axial ligands relative to the porphyrin ring in this system. This, in turn, leads to the formation of a nonplanar porphyrin core conformation that is a mixture of ruffle- and saddle-type distortions. The intricate hydrogen bonding between the cations and anions in 2 results in an unusually long mean Co – Naminecoordination distance of 2.033(4) Å, some 0.05 Å longer than previously observed for other bis(primary amine) complexes of Co(III) porphyrins with comparable porphyrin ligands. Density functional theory (DFT) calculations at the B3LYP/LACVP* level of theory have been used to gauge the perturbation of the electronic structure of the [ Co ( TPP )( BzNH2)2]+cation caused by the N – H ⋯ SCN and N – H ⋯ NCS hydrogen-bonded SCN-ions. The calculations show that partial mixing of the anion MOs with those of the porphyrin cation lead to changes in the electron populations of the 3d orbitals of up to 0.42 e as well as more nearly tetragonal electronic symmetry for the Co(III) ion as a result of adjustments of the relative energies of the MOs with predominantly 3d character.
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Affiliation(s)
- Orde Q. Munro
- School of Chemistry, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
| | - Nicole Pearson
- School of Chemistry, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
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12
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Harmon HJ. Specific visible spectral changes induced by guanine binding to cytosine-derivatized porphyrin. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424602000117] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The interaction of the free nucleic acid bases adenine, cytosine, and thymidine with meso-tri(4-sulfonatophenyl) meso 4-phenyl porphyrin cytosine amide (TPSC) trisodium salt at pH 5.9, 7.4, and 9.3 results is a decrease in the absorbance of the Soret (B-band) at 413 nm of TPSC. A decrease in Soret band absorbance is observed with guanine below pH 8; at higher pH values a new absorbance band at 424 nm is observed. The appearance of the band is consistent with hydrogen bonding between the cytosine-functionalized porphyrin and guanine and the resulting perturbation of the electron orbitals of the porphyrin.
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Affiliation(s)
- H. James Harmon
- Department of Physics, Oklahoma State University, Stillwater, OK, USA
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13
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Konarev DV, Khasanov SS, Faraonov MA, Lyubovskaya RN. Coordination of fullerene C60 and benzonitrile to iron(ii) tetraphenylporphyrin in the FeIITPP·C60·(C6H4Cl2)2·(C6H14)0.5 and FeIITPP·(C6H5CN)2 complexes. CrystEngComm 2012. [DOI: 10.1039/c2ce25295c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Munro OQ, Camp GL, Carlton L. Structural,
103
Rh NMR and DFT Studies of a Bis(phosphane)Rh
III
–Porphyrin Derivative. Eur J Inorg Chem 2009. [DOI: 10.1002/ejic.200800837] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Orde Q. Munro
- School of Chemistry, University of KwaZulu‐Natal, Private Bag X01, Scottsville, 3209, Pietermaritzburg, South Africa, Fax: +27‐33‐260‐5009
| | - Greville L. Camp
- School of Chemistry, University of KwaZulu‐Natal, Private Bag X01, Scottsville, 3209, Pietermaritzburg, South Africa, Fax: +27‐33‐260‐5009
| | - Laurence Carlton
- School of Chemistry, University of the Witwatersrand, P. O. Wits 2050, Johannesburg, South Africa, Fax: +27‐11‐717‐6749
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15
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Hikal WM, Harmon HJ. Photocatalytic self-assembled solid porphyrin microcrystals from water-soluble porphyrins: Synthesis, characterization and application. Polyhedron 2009. [DOI: 10.1016/j.poly.2008.10.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Hikal WM, Harmon HJ. Early events in 2,4,6-trinitrotoluene (TNT) degradation by porphyrins: binding of TNT to porphyrin by hydrophobic and hydrogen bonds. JOURNAL OF HAZARDOUS MATERIALS 2008; 154:826-831. [PMID: 18063299 DOI: 10.1016/j.jhazmat.2007.10.098] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 09/25/2007] [Accepted: 10/29/2007] [Indexed: 05/25/2023]
Abstract
The interaction of meso-tri(4-sulfonatophenyl)mono(4-carboxyphenyl) porphyrin (C1TPP) with 2,4,6-trinitrotoluene (TNT) has been explored by UV-vis and fluorescence spectroscopy. The influence of temperature on the interaction has also been studied. C1TPP binds to TNT at pH 7.0 at room temperature via 1.94 kcal/mole hydrogen bonds with absorbance loss at 412-413 nm and the appearance of a new peak at 422-424 nm. The hydrogen binding of TNT to C1TPP was confirmed by the dissolution of the complex upon the addition of urea. Increasing the temperature results in the appearance of a new absorbance peak at 540 nm and absorbance loss at 515 nm with activation energy of 29.7 kcal/mole in the range of the hydrophobic bond energy. This suggests the hydrophobic bonding of TNT with the pyrrole nitrogens in the porphyrin. Increasing the concentration of the TNT in the solution quenches the fluorescence of the porphyrin following the Stern-Volmer equation. The association constants calculated from absorbance and fluorescence are expectedly similar.
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Affiliation(s)
- Walid M Hikal
- Department of Physics, Oklahoma State University, Stillwater, OK 74078, USA.
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17
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Carmen Lequerica MD, Baena MJ, Espinet P. Ionic metallomesogens derived from silver(I) bis-amine complexes: Structure and mesogenic behavior. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2007.11.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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18
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Arai T, Ishibashi K, Tomizaki KY, Kato T, Nishino N. Slipping of a histidine improved the peroxidase activity of a de novo designed polypeptide packing an iron porphyrin. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.02.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Wyllie GRA, Schulz CE, Scheidt WR. Five- to six-coordination in (nitrosyl)iron(II) porphyrinates: effects of binding the sixth ligand. Inorg Chem 2003; 42:5722-34. [PMID: 12950223 PMCID: PMC2080624 DOI: 10.1021/ic034473t] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report structural and spectroscopic data for a series of six-coordinate (nitrosyl)iron(II) porphyrinates. The structures of three tetraphenylporphyrin complexes [Fe(TPP)(NO)(L)], where L = 4-(dimethylamino)pyridine, 1-methylimidazole, 4-methylpiperidine, are reported here to a high degree of precision and allow observation of several previously unobserved structural features. The tight range of bonding parameters for the [FeNO] moiety for these three complexes suggests a canonical representation for six-coordinate systems (Fe-N(p) = 2.007 A, Fe-N(NO) = 1.753 A, angle FeNO = 138.5 degrees ). Comparison of these data with those obtained previously for five-coordinate systems allows the precise determination of the structural effects of binding a sixth ligand. These include lengthening of the Fe-N(NO) bond and a decrease in the Fe-N-O angle. Several other aspects of the geometry of these systems are also discussed, including the first examples of off-axis tilting of a nitrosyl ligand in a six-coordinate [FeNO](7) heme system. We also report the first examples of Mössbauer studies for these complexes. Measurements have been made in several applied magnetic fields as well as in zero field. The spectra differ from those of their five-coordinate analogues. To obtain reasonable fits to applied magnetic field data, rotation of the electrical field gradient is required, consistent with differing g-tensor orientations in the five- vs six-coordinate species.
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20
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Munro OQ, McKenzie JM, Strydom SD, Gravestock D. Conformational analysis: crystallographic, NMR, and molecular mechanics studies of flexible sulfonic esters. J Org Chem 2003; 68:2448-59. [PMID: 12636415 DOI: 10.1021/jo0260342] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two novel X-ray structures of the sulfonic ester derivatives 2-(6-iodo-1,3-benzodioxol-5-yl)ethyl 4-nitrobenzenesulfonate, 3, and 2-(6-iodo-1,3-benzodioxol-5-yl)ethyl 4-methylbenzenesulfonate, 4, have been obtained in a study aimed at analyzing the structures and conformations of sulfonic ester derivatives that are routinely used in alkaloid syntheses. The crystal structure of 4 is highly unusual, containing four independent molecules that belong to two distinct conformational types: (1) a hairpin conformation (stabilized mainly by intramolecular pi-stacking) and (2) a stepped conformation (stabilized mainly by intermolecular pi-stacking). Compound 3, on the other hand, crystallizes exclusively as the hairpin conformer. New MM+ force field parameters for sulfonic esters have been developed using the X-ray data, empirical rules, and DFT calculations to estimate the bond dipole parameters. Grid searches of conformational space for 3 and 4 using MM methods show that there are several gas-phase conformations within 5 kcal/mol of the global minimum and that the lowest energy conformations (by approximately 4.6 kcal/mol) are of the hairpin type. Analysis of the MM conformational energies suggests that the dominant intramolecular interaction stabilizing the hairpin conformations of 3 and 4 is van der Waals attraction. Moreover, the lattice energies for packing the hairpin conformations of 3 and 4 are approximately 4 kcal/mol more favorable than for the stepped conformations. Various intermolecular interactions contribute to the complexity of the observed crystal structures of 3 and 4, including electrostatic attraction between O and I atoms in neighboring molecules. Langevin dynamics (LD) simulations at several temperatures (6.0 ns, friction coefficient = 2.5 ps(-1)) indicate that the conformational exchange rates are approximately 10(10)-10(11) s(-1) over the temperature range 213-400 K, accounting for the temperature-independent (1)H NMR spectra of 3 and 4.
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Affiliation(s)
- Orde Q Munro
- School of Chemical and Physical Sciences, University of Natal, Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa.
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21
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Simonneaux G, Kobeissi M, Toupet L. Electronic structure of iron chlorins: characterization of bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(III)triflate and bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(II). Inorg Chem 2003; 42:1644-51. [PMID: 12611534 DOI: 10.1021/ic026039h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis and characterization of the two iron chlorin complexes [Fe(III)(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) and Fe(II)(TPC)[(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2))](2) (2) are reported. The crystal structure of complex 1 has been determined. The X-ray structure shows that the porphyrinate rings are weakly distorted. The metal-nitrogen distances to the reduced pyrrole N(4), 2.034(4) A, and to the pyrrole trans to it N(2), 2.012(4) A, are longer than the distances to the two remaining nitrogens [N(1), 1.996(4) A, and N(3), 1.984(4) A], leading to a core-hole expansion of the macrocycle due to the reduced pyrrole. The (1)H NMR isotropic shifts at 20 degrees C of the different pyrrole protons of 1 varied from -0.8 to -48.3 ppm according to bis-ligated complexes of low-spin ferric chlorins. The EPR spectrum of [Fe(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) in solution is rhombic and gives the principal g values g(1) = 2.70, g(2) = 2.33, and g(3) = 1.61 (Sigmag(2) = 15.3). These spectroscopic observations are indicative of a metal-based electron in the d(pi) orbital for the [Fe(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) complex with a (d(xy))(2)(d(xz)d(yz))(3) ground state at any temperature. The X-ray structure of the ferrous complex 2 also shows that the porphyrinate rings are weakly distorted. The metal-nitrogen distances to the reduced pyrrole N(4), 1.991(5) A, and to the pyrrole trans to it N(2), 2.005(6) A, are slightly different from the distances to the two remaining nitrogens [N(1), 1.988(5) A, and N(3), 2.015(5) A], leading to a core-hole expansion of the macrocycle due to the reduced pyrrole.
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Affiliation(s)
- Gérard Simonneaux
- Laboratoire de Chimie Organométallique et Biologique, UMR CNRS 6509, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France.
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22
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Marques HM, Brown KL. Molecular mechanics and molecular dynamics simulations of porphyrins, metalloporphyrins, heme proteins and cobalt corrinoids. Coord Chem Rev 2002. [DOI: 10.1016/s0010-8545(01)00411-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Munro OQ, Shabalala SC, Brown NJ. Structural, computational, and (59)Co NMR studies of primary and secondary amine complexes of Co(III) porphyrins. Inorg Chem 2001; 40:3303-17. [PMID: 11421673 DOI: 10.1021/ic000976c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Four novel low-spin bis(amine) Co(III) porphyrins [Co(TPP)(BzNH(2))(2)](SbF(6)), 1, [Co(TPP)(1-BuNH(2))(2)](SbF(6)), 2, [Co(TPP)(PhCH(2)CH(2)NH(2))(2)](SbF(6)), 3, and [Co(TPP)(1-MePipz)(2)](SbF(6)), 4, have been synthesized and characterized by low-temperature X-ray crystallography, IR, electronic, and NMR ((1)H, (13)C, and (59)Co) spectroscopy. The mean Co-N(p) distance for the four structures is 1.986(1) A. The Co-N(ax) distances for the 1 degrees amine derivatives average to 1.980(5) A; the axial bonds of the 2 degrees amine derivative are significantly longer, averaging 2.040(1) A. The porphyrin core conformation of 4 is significantly nonplanar (mixture of S(4)-ruf and D(2d)-sad distortions) due to a staggered arrangement of the axial ligands over the porphyrin core and meso-phenyl group orientations < 90 degrees. The X-ray structures have been used with the coordinates for [Co(TPP)(Pip)(2)](NO(3)) (Scheidt et al. J. Am. Chem. Soc. 1973, 95, 8289-8294.) to parametrize a molecular mechanics (MM) force field for bis(amine) complexes of Co(III) porphyrins. The calculations show that two types of crystal packing interactions (van der Waals and hydrogen bonding) largely control the crystallographically observed conformations. Gas phase conformational energy surfaces have been computed for these complexes by dihedral angle driving methods and augmented with population distributions calculated by MD simulations at 298 K; the calculations demonstrate that the bis(1 degrees amine) complexes are significantly more flexible than the bis(2 degrees amine) analogues. (59)Co NMR spectra have been acquired for a range of [Co(TPP)(amine)(2)]Cl derivatives as a function of temperature. The (59)Co chemical shifts increase linearly with increasing temperature due to population of thermally excited vibrational levels of the (1)A(1) ground state. Activation energies for molecular reorientation (tumbling) have been determined from an analysis of the (59)Co NMR line widths as a function of 1/T; lower barriers exist for the conformationally rigid 2 degrees amine derivatives (2.6-3.8 kJ mol(-1)). The (59)Co chemical shifts vary linearly with the DFT-calculated radial expectation values <r(-3)>(3d) for the Co(III) ion. The correlation leads to the following order for the sigma-donor strengths of the axial ligands: BzNH(2) > or = Cl(-) > 1-BuNH(2) > PhCH(2)CH(2)NH(2) > 1-Bu(2)NH > Et(2)NH. The (59)Co NMR line widths are proportional to the square of the DFT-calculated valence electric field gradient at the Co nucleus. Importantly, this is the first computational rationalization of the (59)Co NMR spectra of Co(III) porphyrins.
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Affiliation(s)
- O Q Munro
- School of Chemical and Physical Sciences, University of Natal, Pietermaritzburg, Private Bag X01, Scottsville, 3209, South Africa.
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