Electron Transfer from Aromatic Amines to Excited Coumarin Dyes:  Fluorescence Quenching and Picosecond Transient Absorption Studies

2000 ◽  
Vol 104 (3) ◽  
pp. 673-680 ◽  
Author(s):  
Sanjukta Nad ◽  
Haridas Pal
Keyword(s):  
Electron Transfer ◽  
Fluorescence Quenching ◽  
Aromatic Amines ◽  
Transient Absorption ◽  
Absorption Studies ◽  
Coumarin Dyes

A comparative study on electron-transfer fluorescence quenching by aliphatic and aromatic amines

2000 ◽  
Vol 137 (2-3) ◽  
pp. 93-97 ◽  
Author(s):  
Taeko Niwa Inada ◽  
Koichi Kikuchi ◽  
Yasutake Takahashi ◽  
Hiroshi Ikeda ◽  
Tsutomu Miyashi
Keyword(s):  
Electron Transfer ◽  
Fluorescence Quenching ◽  
Comparative Study ◽  
Aromatic Amines

Excited state electron transfer in A2 and A2B2 functionalized zinc porphyrins carrying rigid and flexible β-pyrrole π-extended substituents

2020 ◽  
Vol 24 (05n07) ◽  
pp. 904-919
Author(s):  
Michael B. Thomas ◽  
Siddhartha Kumar ◽  
Timothy Esquivel ◽  
Hong Wang ◽  
Francis D’Souza
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Transient Absorption ◽  
Binding Constants ◽  
Free Energy Calculations ◽  
Stable Complex ◽  
State Electron ◽  
Femtosecond Transient Absorption ◽  
Absorption Studies ◽  
Zinc Porphyrins

Optical absorption and emission, electrochemical, and photochemical properties of peripherally functionalized with flexible and rigid [Formula: see text]-extended substituents on A2 and A2B2 type zinc porphyrins is investigated. The significance of rigid [Formula: see text]-substituents over flexible ones in governing the spectral properties is unraveled. Flexible [Formula: see text]-substituents on the porphyrin ring caused appreciable spectral broadening compared to porphyrin carrying rigid [Formula: see text]-substituents. Further, supramolecular dyads are formed by coordinating phenyl imidazole functionalized fullerene, C[Formula: see text]Im. The calculated binding constants for the 1:1 complexes is in the order of 2–7 × 105 M[Formula: see text] suggesting stable complex formation. Free-energy calculations performed according to the Rehm–Weller approach suggested possibility of excited state electron transfer in these dyads. Femtosecond transient absorption studies of the dyads performed in [Formula: see text]-dichlorobenzene showed evidence of occurrence of electron transfer from the singlet-excited state that was in competition with the intersystem crossing process to populate the triplet-excited state of porphyrins.

Electron-transfer fluorescence quenching by aliphatic amines

1980 ◽  
Vol 33 (1) ◽  
pp. 177 ◽  
Author(s):  
AR Watkins
Keyword(s):  
Electron Transfer ◽  
Fluorescence Quenching ◽  
Tertiary Amine ◽  
Aromatic Amines ◽  
Aliphatic Amines ◽  
Aromatic Molecule ◽  
Intermediate Products

Electron-transfer interaction of an excited aromatic molecule with an aliphatic tertiary amine leads to a pattern of intermediate products not to be expected from earlier work with aromatic amines. The reasons for this phenomenon are briefly discussed.

scholarly journals Tryptophan-to-heme electron transfer in ferrous myoglobins

2015 ◽  
Vol 112 (18) ◽  
pp. 5602-5606 ◽  
Author(s):  
Roberto Monni ◽  
André Al Haddad ◽  
Frank van Mourik ◽  
Gerald Auböck ◽  
Majed Chergui
Keyword(s):  
Electron Transfer ◽  
Fluorescence Quenching ◽  
Heme Proteins ◽  
Anion Radical ◽  
Transient Absorption ◽  
Physiological Conditions ◽  
Decay Times ◽  
First Time

It was recently demonstrated that in ferric myoglobins (Mb) the fluorescence quenching of the photoexcited tryptophan 14 (*Trp14) residue is in part due to an electron transfer to the heme porphyrin (porph), turning it to the ferrous state. However, the invariance of *Trp decay times in ferric and ferrous Mbs raises the question as to whether electron transfer may also be operative in the latter. Using UV pump/visible probe transient absorption, we show that this is indeed the case for deoxy-Mb. We observe that the reduction generates (with a yield of about 30%) a low-valence Fe–porphyrin π [FeII(porph●−)] -anion radical, which we observe for the first time to our knowledge under physiological conditions. We suggest that the pathway for the electron transfer proceeds via the leucine 69 (Leu69) and valine 68 (Val68) residues. The results on ferric Mbs and the present ones highlight the generality of Trp–porphyrin electron transfer in heme proteins.

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