Intramolecular Triplet-Triplet Energy Transfer in Short Flexible Bichromophoric Amino Acids, Dipeptides and Carboxylic Acid Diester

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Title:Intramolecular Triplet-Triplet Energy Transfer in Short Flexible Bichromophoric Amino Acids, Dipeptides and Carboxylic Acid Diester
Creators:
Zabadal, Miroslav
Heger, Dominik
Klán, Petr
Kříž, Zdeněk
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 69, 4, pp. 776-796
Uncontrolled Keywords:Photokinetics, Triplet-triplet energy transfer, Esters, Phenacyl, Amino acids, Bichromophore, Through-space mechanism

Abstract

Efficiencies of the intramolecular triplet-triplet energy transfer (ITET) in various bichromophoric amino acids (glycine, valine, phenylalanine, and sarcosine), dipeptides (glycylglycine, phenylalanylphenylalanine), and a simple diester, with the benzoyl and naphthyl terminal groups serving as donor and acceptor, respectively, have been determined by the steady-state photokinetic measurements. The magnitude of the transfer rate constants (&gt;10<sup>8</sup> s<sup>-1</sup>) and the number of bonds separating the chromophores (8 or 11 atoms) suggest a through-space exothermic exchange mechanism in all cases. The influence of interchromophore distance, the character of the connecting chain as well as of side chains, was evaluated. While the most efficient energy transfer was found in a flexible diester and in valine- and sarcosine-based molecules due to the steric effect of the side hydrocarbon groups, the benzyl groups in the phenylalanine and phenylalanylphenylalanine-based bichromophores had a suppressing effect on ITET. Rigidity of the peptide bond in short bichromophoric compounds causes that a large number of favorable geometries preexist already before excitation; thus the intramolecular processes are controlled by ground-state conformational distribution. Replacing this bond by a less rigid ester moiety would allow that certain unfavorable conformations may coil to favorable ones within the excited-state lifetime (a rotation-controlled photochemical model). Some conclusions were supported by a conformational search of the potential energy surface and molecular dynamics simulations. <p>

Title:Intramolecular Triplet-Triplet Energy Transfer in Short Flexible Bichromophoric Amino Acids, Dipeptides and Carboxylic Acid Diester
Creators:
Zabadal, Miroslav
Heger, Dominik
Klán, Petr
Kříž, Zdeněk
Uncontrolled Keywords:Photokinetics, Triplet-triplet energy transfer, Esters, Phenacyl, Amino acids, Bichromophore, Through-space mechanism
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:69
Number:4
Page Range:pp. 776-796
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20040776UNSPECIFIED
ID Code:2242
Item Type:Article
Deposited On:06 Feb 2009 17:16
Last Modified:06 Feb 2009 16:16

Citation

Zabadal, Miroslav; Heger, Dominik; Klán, Petr; Kříž, Zdeněk (2004) Intramolecular Triplet-Triplet Energy Transfer in Short Flexible Bichromophoric Amino Acids, Dipeptides and Carboxylic Acid Diester. Collection of Czechoslovak Chemical Communications, 69 (4). pp. 776-796. ISSN 0010-0765

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