Evidence of coupled photoinduced proton transfer and intramolecular charge transfer reaction in para-N,N-dimethylamino orthohydroxy benzaldehyde: Spectroscopic and theoretical studies

Mahanta, Subrata; Singh, Rupashree Balia; Kar, S.; Guchhait, Nikhil

doi:10.1016/j.chemphys.2008.10.002

Cited by 17 publications

(38 citation statements)

References 65 publications

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“…By avoiding these highly endothermic reaction steps, the likelihood of maintaining a reaction cycle with overall low kinetic barriers is increased. Many examples of PCET exist for different biological [24,25] and nonbiological [26,27] systems. They have been studied both experimentally [28,29] and theoretically [30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Reductive activation of the heme iron–nitrosyl intermediate in the reaction mechanism of cytochrome c nitrite reductase: a theoretical study

Bykov

Neese

2012

J Biol Inorg Chem

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Cytochrome c nitrite reductase catalyzes the six-electron, seven-proton reduction of nitrite to ammonia without release of any detectable reaction intermediate. This implies a unique flexibility of the active site combined with a finely tuned proton and electron delivery system. In the present work, we employed density functional theory to study the recharging of the active site with protons and electrons through the series of reaction intermediates based on nitrogen monoxide [Fe(II)-NO(+), Fe(II)-NO·, Fe(II)-NO(-), and Fe(II)-HNO]. The activation barriers for the various proton and electron transfer steps were estimated in the framework of Marcus theory. Using the barriers obtained, we simulated the kinetics of the reduction process. We found that the complex recharging process can be accomplished in two possible ways: either through two consecutive proton-coupled electron transfers (PCETs) or in the form of three consecutive elementary steps involving reduction, PCET, and protonation. Kinetic simulations revealed the recharging through two PCETs to be a means of overcoming the predicted deep energetic minimum that is calculated to occur at the stage of the Fe(II)-NO· intermediate. The radical transfer role for the active-site Tyr(218), as proposed in the literature, cannot be confirmed on the basis of our calculations. The role of the highly conserved calcium located in the direct proximity of the active site in proton delivery has also been studied. It was found to play an important role in the substrate conversion through the facilitation of the proton transfer steps.

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Section: Introductionmentioning

confidence: 99%

Reductive activation of the heme iron–nitrosyl intermediate in the reaction mechanism of cytochrome c nitrite reductase: a theoretical study

Bykov

Neese

2012

J Biol Inorg Chem

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“…The TCSPC measurements of the temporal behaviors of the fluorescence bands are shown in Figure 7. These results are at odds with the conclusion of Mahanta et al 15 that the fluorescence Figure 7. Temporal characteristics of the fluorescence from the ππ* state of the keto form of DMAHBA, measured at different emission wavelengths by the time-correlated single-photon counting (TCSPC) following 315 nm excitation.…”

Section: Resultsmentioning

confidence: 62%

“…A sample compound of DMAHBA was synthesized as described in ref 15 and purified by column chromatography. The steady-state UV absorption and fluorescence spectra were measured by using a UV spectrophotometer (Shimadzu, UV-1800) and a spectrofluorometer (Horiba/Jobin Yvon, FluoroMax-4), ABSTRACT: TDDFT calculations, picosecond transient absorption, and timeresolved fluorescence studies of 4-dimethylamino-2-hydroxy-benzaldehyde (DMAHBA) have been carried out to study the electron and proton transfer processes in polar (acetonitrile) and nonpolar (n-hexane) solvents.…”

Section: Experimental and Calculations Sectionmentioning

confidence: 99%

“…12À14 From the detailed study of absorption and fluorescence, Mahanta et al 15 proposed that DMAHBA exhibits coupled proton and electron transfer in polar solvents and only the excited-state proton transfer in nonpolar solvents. As in DMABA, 13,16 the electron transfer in the polar solvents of DMAHBA may be assumed to involve the formation of the twisted intramolecular charge transfer (TICT) state 17,18 in which the positively charged dimethylamino group is twisted with respect to the plane of the negatively charged orthohydroxybenzaldehyde moiety.…”

Section: Introductionmentioning

confidence: 99%

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Coupled Electron and Proton Transfer Processes in 4-Dimethylamino-2-hydroxy-benzaldehyde

Zgierski¹,

Fujiwara

Lim

2011

J. Phys. Chem. A

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“…The electronic absorption around 4.4 eV in [C 4 mim][PF 6 ] provides information on the polarity of the RTIL and the dynamics of the diffusion. Here, the possible excited species are induced by the donor-acceptor charge transfer, proton transfer, molecular conformational change, hydrogen bonding ability, and polarity (Mahanta et al, 2008). For the [DEME] [BF 4 ]-H 2 O mixture, we focus on the anomalous optical absorption at 90-95 mol%.…”

Section: H/d Effects At 1 Mol% Water Mixturementioning

confidence: 99%

H/D Effects of Water in Room Temperature Ionic Liquids

Abe¹,

Yoshimura²

2011

Ionic Liquids: Theory, Properties, New Approaches

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Evidence of coupled photoinduced proton transfer and intramolecular charge transfer reaction in para-N,N-dimethylamino orthohydroxy benzaldehyde: Spectroscopic and theoretical studies

Cited by 17 publications

References 65 publications

Reductive activation of the heme iron–nitrosyl intermediate in the reaction mechanism of cytochrome c nitrite reductase: a theoretical study

Reductive activation of the heme iron–nitrosyl intermediate in the reaction mechanism of cytochrome c nitrite reductase: a theoretical study

Coupled Electron and Proton Transfer Processes in 4-Dimethylamino-2-hydroxy-benzaldehyde

H/D Effects of Water in Room Temperature Ionic Liquids

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