Optical properties of metalloporphyrin excited states

Rodríguez, Juan; Kirmaier, Christine; Holten, Dewey

doi:10.1021/ja00199a004

Cited by 336 publications

(416 citation statements)

References 3 publications

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“…This feature is known to be insensitive to the peripheral substituents on the porphyrin macrocycle or to the electronic configuration of the central metal. 27 The triplet state absorption spectra of the porphyrin arrays (Z2, Z3, Z6, and Z12) were almost the same without any vibronic structure (Figure 4). The lack of the vibronic structure in the T-T absorption spectra of the porphyrin arrays might be attributable to the increased number of upper electronic states with the linkage of porphyrin moieties.…”

Section: Resultsmentioning

confidence: 90%

Energy Relaxation Dynamics of Excited Triplet States of Directly Linked Zn(II)Porphyrin Arrays

Song

Cho

Yoon

et al. 2002

Bulletin of the Korean Chemical Society

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The energy relaxation dynamics of the lowest excited singlet and triplet states of the Zn(II)porphyrin monomer and its directly linked arrays were comparatively investigated with increasing the number of porphyrin moieties. While the fluorescence decay rates and quantum yields of the porphyrin arrays increased with the increase of porphyrin units, their triplet-triplet (T-T) absorption spectra and decay times remained almost the same. The difference in the trends of energy relaxation dynamics between the excited singlet and triplet states has been discussed in view of the electronic orbital configurations.

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Section: Resultsmentioning

confidence: 90%

Energy Relaxation Dynamics of Excited Triplet States of Directly Linked Zn(II)Porphyrin Arrays

Song

Cho

Yoon

et al. 2002

Bulletin of the Korean Chemical Society

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“…The reduced porphyrin macrocycle occurs in the pheophytins and, further complexed with magnesium, in the chlorophylls both of which are involved in light harvesting and the transformation of trapped sun light into stored chemical energy in the course of photosynthesis [74]. Because of this significance as biological reaction centers, but also because of their function as photosensitizers in photodynamic therapy and as catalysts in precision macromolecular synthesis [75,76], porphyrins have been the focus of a series of time-resolved spectroscopic investigations over the past years in order to gain a better insight into the internal excited-state dynamics [77][78][79][80][81][82][83][84][85]. For these studies a wide variety of time-resolved techniques has been used including transient absorption, nonlinear absorption, fluorescence and also four-wave-mixing spectroscopy.…”

Section: Protochlorophyllide Amentioning

confidence: 99%

Femtosecond time‐resolved spectroscopy on biological photoreceptor chromophores

Schmitt¹,

Dietzek

Hermann

et al. 2007

Laser & Photonics Reviews

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This paper reviews our results on femtosecond timeresolved spectroscopy (transient absorption, transient-grating and fluorescence spectroscopy) to study the photophysics and photochemistry of the two very important biological photoreceptor chromophores phycocyanobilin (PCB) and protochlorophyllide a (PChla). The compound PCB serves as a model chromophore for the photoreceptor phytochrome. By means of transient-grating spectroscopy where the excitation wavelength was varied over the spectral region of the S0 → S1-absorption the ultrafast processes were studied upon excitation with varying excess energy delivered to the system. On the basis of the results obtained, both the rate of the photoreaction in PCB and the rate of the decay of different excited-state species via different decay channels depend on the excitation wavelength. Furthermore, transient absorption experiments illuminating the excited-state dynamics of PChla, a porphyrin-like compound and, as substrate of the NADPH/protochlorophyllide oxidoreductase (POR), a precursor of the chlorophyll biosynthesis are presented. In addition to pump-energy-dependent measurements performed with PChla dissolved in methanol, the excited-state dynamics of PChla was interrogated in different solvents that were chosen to mimic different environmental conditions. In addition to the femtosecond time-resolved absorption experiments the picosecond time-resolved fluorescence of the system was studied. The transient absorption and time-resolved fluorescence data allow suggesting a detailed model for the excited-state relaxation of PChla describing the excited-state processes in terms of The model suggested to account for the excited-state relaxation processes in protochlorophyllide a upon photoexcitation is presented a branching of the initially excited state population into a reactive and nonreactive path. Thus, the excited-state potential energy surface exhibits two distinct S1 and Sx minima separated from the Franck-Condon region along two most likely orthogonal reaction coordinates. Finally, the model derived is related to models suggested to account for the reduction of PChla to chlorophyllide a within the natural enzymatic environment of POR.

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“…Besides bleaching in the Soretand Q-band region, the most important characteristic is the triplet maximum at 775 nm. 8 The differential absorption changes of the SWNT-PSS n2 /H 2 P 81 ensemble, on the other hand, are governed by broad absorptions in the 550-800 nm range, indicating a H 2 P 81 centered redox product. 8 The reduced form of SWNT-PSS n2 has a broad maximum at 450 nm 9 that is masked by the strong changes associated with the redox chemistry of H 2 P 81 .…”

Section: Received (In Cambridgementioning

confidence: 99%

“…8 The differential absorption changes of the SWNT-PSS n2 /H 2 P 81 ensemble, on the other hand, are governed by broad absorptions in the 550-800 nm range, indicating a H 2 P 81 centered redox product. 8 The reduced form of SWNT-PSS n2 has a broad maximum at 450 nm 9 that is masked by the strong changes associated with the redox chemistry of H 2 P 81 . Under anaerobic conditions, the lifetime of 14 ms observed for the newly formed ion pair is remarkably long.…”

Section: Received (In Cambridgementioning

confidence: 99%