Ligand photolysis and recombination of Fe(II) protoporphyrin IX complexes in dimethyl sulfoxide

Larsen, Randy W.; Findsen, E. W.; Nalliah, Ruth E.

doi:10.1016/0020-1693(95)04488-u

Cited by 11 publications

(12 citation statements)

References 17 publications

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“…The optical absorption of the (DMSO) 2 Fe II PPIX and (CO)(DMSO)Fe II PPIX complexes are displayed in Figure . The optical absorption spectrum of the (DMSO) 2 Fe II PPIX displays a Soret maximum at 424 nm with visible bands located at 556 nm (α-band) and 527 nm (β-band) consistent with previous results. , The positions of these bands are characteristic of six-coordinate, low-spin heme complexes (see Table ). Exposure of the (DMSO) 2 Fe II PPIX to CO results in a hypsochromic shift in the Soret band to 415 nm and bathochromic shifts in both the α- and β-bands to 568 and 535 nm, respectively (Figure , trace b).…”

Section: Resultssupporting

confidence: 89%

“…Nanosecond transient absorption and resonance Raman data were obtained with instrumentation described in detail elsewhere. , Nanosecond transient absorption data were obtained by exciting the sample in a 1-cm quartz optical cuvette with a 10 ns pulse from a frequency doubled Nd:YAG laser (Continium SureLite II, 532 nm, 3.0 mJ/pulse). The change in absorbance was monitored by focusing the the arc of a 75-W Xe arc lamp through the sample and overlapping with the excitation pulse.…”

Section: Methodsmentioning

confidence: 99%

“…It has recently been shown that the (DMSO) 2 Fe II PPIX complex forms a photolabile six-coordinate low-spin complex. , We have previously found that photolysis of this complex yields a five-coordinate, high-spin (DMSO)Fe II PPIX complex that exhibits a relatively slow rate of recombination ( k obs = ∼2.0 × 10 6 s -1 ) when compared to recombination rates of nitrogen-based ligands. This slow recombination rate was attributed to strong dipolar interactions between the DMSO ligand and the transient five-coordinate high-spin heme.…”

Section: Introductionmentioning

confidence: 96%

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Structure and Dynamics of CO−Iron(II) Protoporphyrin IX in Dimethyl Sulfoxide

1996

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In this report we examine the steady-state optical absorption, steady state and transient vibrational structure, and ligand rebinding kinetics of (CO)FeII protoporphyrin IX ((CO)FeIIPPIX) in dimethyl sulfoxide (DMSO). Steady state optical absorption and resonance Raman spectra of this complex are characteristic of heme iron that is six-coordinate and low-spin. Absorption maxima are observed at 415 nm (Soret), 568 nm (α-band), and 535 nm (β-band), and vibrational bands are observed at 1370 cm-1 (ν4), 1496 cm-1 (ν3), 1551 cm-1 (ν38), 1584 cm-1 (ν2), and 1626 cm-1 (νC  C). The transient absorption difference spectrum subsequent to photolysis displays an absorption maximum at 433 nm and a minimum at 414 nm that decays biphasically with pseudo-first-order rate constants of (2.11 ± 0.024) × 106 s-1 and (2.29 ± 0.036) × 102 s-1. The corresponding transient resonance Raman spectrum displays vibrational bands at 1356 cm-1 (ν4), 1470 cm-1 (ν3), 1559 cm-1 (ν2), 1584 cm-1 (ν37), and 1618 cm-1 (νC  C). These results are consistent with the formation of a five-coordinate and high-spin transient species that is identical to the photolytic transient observed upon photolysis of the (DMSO)2FeIIPPIX complex (i.e., (DMSO)FeIIPPIX). The decay of this transient species is consistent with the binding of a DMSO to the five-coordinate heme iron followed by substitution of a bound DMSO with CO.

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Section: Resultssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Structure and Dynamics of CO−Iron(II) Protoporphyrin IX in Dimethyl Sulfoxide

1996

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“…Randy Larsen has performed picosecond transient absorption studies on [Fe II (PPIX)(dmso) 2 ] 2+ (PPIX is protoporphyrin IX) and found evidence for a long-lived intermediate formed from photolysis. − Based on the bathochromic shift of the Soret transition, the photolytic intermediate is assigned as a five-coordinate, high-spin Fe II (PPIX) featuring an S-bonded dmso ligand. The observed 100 ps transient absorption spectrum reveals a Soret that is consistent with a five-coordinate, Fe(II) porphyrin with imidazole or thiolate donors and dissimilar to Fe(II) heme phenolate species.…”

Section: First-row Transition Metal Complexesmentioning

confidence: 99%

A Future Perspective on Phototriggered Isomerizations of Transition Metal Sulfoxides and Related Complexes

et al. 2021

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Photochromic molecules are examples of light-activated bistable molecules. We highlight the design criteria for a class of ruthenium and osmium sulfoxide complexes that undergo phototriggered isomerization of the bound sulfoxide. The mode of action in these complexes is an excited-state isomerization of the sulfoxide from S-bonded to O-bonded. We discuss the basic mechanism for this transformation and highlight specific examples that demonstrate the effectiveness and efficiency of the isomerization. We subsequently discuss future research directions within the field of phototriggered sulfoxide isomerizations on transition metal polypyridine complexes. These efforts involve new synthetic directions, including the choice of metal as well as new ambidentate ligands for isomerization.

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“…The transient luminescence experiments were performed using intrumentation described by Larsen and co-workers . Briefly, the sample was excited with a 532 nm laser pulse (7 ns, 150 mW, 10 HZ) from the second harmonic of a Q-Switched Nd:YAG laser (Surelite II, Continuum).…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Physical Characterization of Novel Heme-Based Model Systems for Photoinitiated Electron Transfer. 1. Complexation of a RuProHis Bifunctional Peptide and Microperoxidase-11

et al. 1997

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This paper describes the synthesis and initial physical characterization of a new type of model system for the investigation of photoinitiated electron transfer (ET) in proteins and polypeptides. This system is based upon a derivative of a heme-containing digestion product of cytochrome c, microperoxidase-11 (MP-11). The vacant axial position of the five-coordinate heme of MP-11 is coordinated to the terminal histidine of a dipeptide having a photoactive ruthenium tris(bipyridine) moiety at its other end (RuProHis). Photoexcitation of the ruthenium group results in rapid (k ET > 10 7 s -1 ), reversible ET to the ferric heme. The equilibrium properties of MP-11 and the MP-11/Ru(peptide) complex were characterized with optical absorption, luminescence, and resonance Raman (RR) spectroscopies. Molecular modeling was also employed to examine the structure and energetics of the equilibrium species. Clear evidence for reversible photoinduced ET was observed in time-resolved luminescence and transient resonance Raman studies of the MP-11/RuProHis samples. * To whom correspondence should be addressed. † Abbreviations used: ET, electron transfer; MLCT, metal to ligand charge transfer; CLS, classical least-squares progression; RR, resonance Raman; MP-11, microperoxidase-11 (heme undecapeptide); acMP-11, microperoxidase-11 acetylated at both amino groups as described in the text; RuProHis, (bpy) 2Ru(4-methyl-4′-(histidylprolyl)bpy), where bpy ) 2,2′-bipyridine (see text for details).

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Ligand photolysis and recombination of Fe(II) protoporphyrin IX complexes in dimethyl sulfoxide

Cited by 11 publications

References 17 publications

Structure and Dynamics of CO−Iron(II) Protoporphyrin IX in Dimethyl Sulfoxide

Structure and Dynamics of CO−Iron(II) Protoporphyrin IX in Dimethyl Sulfoxide

A Future Perspective on Phototriggered Isomerizations of Transition Metal Sulfoxides and Related Complexes

Synthesis and Physical Characterization of Novel Heme-Based Model Systems for Photoinitiated Electron Transfer. 1. Complexation of a RuProHis Bifunctional Peptide and Microperoxidase-11

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