Singlet–singlet excited-state absorption and triplet–triplet absorption of meso-tetraphenylporphine

Gratz, H.; Penzkofer, Alfons

doi:10.1016/s0301-0104(00)00049-5

Cited by 30 publications

(16 citation statements)

References 33 publications

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“…Table S1 (Supporting Information) summarizes the various conditions tried, which included changes in solvent, temperature, and addition of different hydrogen iodide scavengers, such as propylene oxide33 and tetrahydrofuran 13. As the E / Z isomerization, which has to take place before photocyclodehydrogenation, is proposed to proceed via a triplet excited state,34 the reaction was also carried out in the presence of triplet sensitizers such as tetrakis( meso ‐phenyl)porphyrin (TPP)35a and C 60 35b. We propose that the failure of the photocyclodehydrogenation is due to kinetic effects.…”

Section: Resultsmentioning

confidence: 99%

Electronically Connected [n]Helicenes: Synthesis and Chiroptical Properties of Enantiomerically Pure (E)‐1,2‐Di([6]helicen‐2‐yl)ethenes

et al. 2013

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We synthesized stilbenoid (E)‐(P,P)‐ and (E)‐(M,M)‐[6]helicene dimers in enantiomerically pure form as part of a program aimed at the exploration of new strategies for the synthesis of large helicenes. The [2+2+2] cyclotrimerization of suitable triynes, reported by Starý and co‐workers, was applied for the preparation of a racemic 2‐hydroxymethylated [6]helicene precursor, which was conveniently resolved by HPLC on a chiral stationary phase. Two optically active helicenes were subsequently connected to the stilbenoid dimer by olefin metathesis. Electronic circular dichroism (ECD) studies of the stilbenoid ethen‐1,2‐diyl‐linked dimer revealed bathochromically shifted ECD bands with exceptionally large Cotton effects relative to those of the monomeric [6]helicenes or to that of a dimeric [6]helicene with a saturated ethan‐1,2‐diyl linker. These comparative studies, complemented by computational investigations, show that the pronounced chiroptical properties of the stilbenoid dimer originate from π‐conjugation between the two [6]helicene moieties and from the rigidity that results from conjugation. All attempts to form (P)‐[13]helicene by photocyclodehydrogenation of the stilbenoid (P,P)‐dimer were unsuccessful.

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Section: Resultsmentioning

confidence: 99%

Electronically Connected [n]Helicenes: Synthesis and Chiroptical Properties of Enantiomerically Pure (E)‐1,2‐Di([6]helicen‐2‐yl)ethenes

et al. 2013

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“…They play a decisive role in light amplification studies (41) and are needed for photoinduced absorption studies in the fluorescence wavelength region ( e.g. analysis of S 1 ‐state excited‐state absorption and emission dynamics in fluorescence spectral region [42]).…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic Characterization of Flavin Mononucleotide Bound to the LOV1 Domain of Phot1 from Chlamydomonas reinhardtii¶

Hölzer

Penzkofer

Fuhrmann

et al. 2007

Photochemistry and Photobiology

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The absorption and emission behavior of flavin mononucleotide (FMN) in the light‐, oxygen‐ and voltage‐sensitive (LOV) domain LOV1 of the photoreceptor Phot1 from the green alga Chlamydomonas reinhardtii was studied. The results from the wild‐type (LOV1‐WT) were compared with those from a mutant in which cysteine 57 was replaced by serine (LOV1‐C57S), and with free FMN in aqueous solution. A fluorescence quantum yield of φF= 0.30 and a fluorescence lifetime of τF= 4.6 ns were determined for FMN in the mutant LOV1‐C57S, whereas these quantities are reduced to about φF= 0.17 and τF= 2.9 ns for LOV1‐WT, indicating an enhanced intersystem crossing in LOV1‐WT because of the adjacent sulfur of C57. A single‐exponential fluorescence decay was observed in picosecond laser time‐resolved fluorescence measurements for both LOV1‐WT and LOV1‐C57S as expected for excited singlet state relaxation by intersystem crossing and internal conversion. An excitation intensity dependent fluorescence signal saturation was observed in steady‐state fluorescence measurements for LOV1‐WT, which is thought to be because of the formation of a long‐lived intermediate flavin‐C(4a)–cysteinyl adduct in the triplet state (few microseconds triplet lifetime, adduct lifetime around 150 s). No photobleaching was observed for LOV1‐C57S, because no thiol group is present in the vicinity of FMN for an adduct formation.

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“…The stimulated emission cross-section characterizes the light amplification property of a medium [42]. It is needed for excited-state absorption studies in the fluorescence region [43]. The Strickler-Berg radiative lifetime, s rad,SB , is calculated from the S 0 -S 1 absorption cross-section spectrum and the fluorescence quantum distribution by the relation [44,45] …”

Section: Methodsmentioning

confidence: 99%

Absorption and emission spectroscopic characterization of 10-phenyl-isoalloxazine derivatives

et al. 2006

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Singlet–singlet excited-state absorption and triplet–triplet absorption of meso-tetraphenylporphine

Cited by 30 publications

References 33 publications

Electronically Connected [n]Helicenes: Synthesis and Chiroptical Properties of Enantiomerically Pure (E)‐1,2‐Di([6]helicen‐2‐yl)ethenes

Electronically Connected [n]Helicenes: Synthesis and Chiroptical Properties of Enantiomerically Pure (E)‐1,2‐Di([6]helicen‐2‐yl)ethenes

Spectroscopic Characterization of Flavin Mononucleotide Bound to the LOV1 Domain of Phot1 from Chlamydomonas reinhardtii¶

Absorption and emission spectroscopic characterization of 10-phenyl-isoalloxazine derivatives

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