Solvochromic effects in model eumelanin compounds

Nighswander-Rempel, Stephen P., Mahadevan, Indumathy B., Bernhardt, Paul V., Butcher, Jessica and Meredith, Paul (2008) Solvochromic effects in model eumelanin compounds. Photochemistry and Photobiology, 84 3: 620-626. doi:10.1111/j.1751-1097.2007.00290.x


Author Nighswander-Rempel, Stephen P.
Mahadevan, Indumathy B.
Bernhardt, Paul V.
Butcher, Jessica
Meredith, Paul
Title Solvochromic effects in model eumelanin compounds
Journal name Photochemistry and Photobiology   Check publisher's open access policy
ISSN 0031-8655
1751-1097
Publication date 2008-02-07
Year available 2008
Sub-type Article (original research)
DOI 10.1111/j.1751-1097.2007.00290.x
Open Access Status Not yet assessed
Volume 84
Issue 3
Start page 620
End page 626
Total pages 7
Place of publication Hoboken, NJ, U.S.A.
Publisher Wiley-Blackwell Publishing
Language eng
Subject 240000 Physical Sciences
C1
970102 Expanding Knowledge in the Physical Sciences
0204 Condensed Matter Physics
Abstract We have created an indolic compound which is ideally suited to the study of the relationship between structure and function in eumelanin formation. N-methyl-5-hydroxy-6-methoxyindole (MHMI) is stable in solid and liquid states, highly soluble in a variety of solvents and forms a dimer only through the 44 positions. The limited binding possibilities are due to functional groups strategically placed to inhibit chemical interactions through the 2 and 7 positions. It forms a crystal structure with a remarkable packing arrangement, with four monomers grouped in parallel pairs spaced 3.5 angstrom apart within each unit cell. Optical spectra reveal a multi-peaked absorbance profile similar to 5,6-dihydroxyindole (DHI) and N-acetyl-tryptophanamide (NATA), and strong fluorescence emission with radiative quantum yields of 29% and 33% in benzene and acetonitrile, respectively. The quantum yield is similar to that of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and shows that solvent aromaticity by itself does not affect the yield. Solution in chloroform results in an almost complete quenching of the fluorescence but an increase in emission is observed with photoactivation. Crystallographic results shown here suggest new structural possibilities for eumelanin and the controlled binding possibilities make this an excellent model for monitoring changes in function with increasing oligomer size in eumelanin formation.
Keyword Eumelanin
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 4 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 7 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Wed, 01 Apr 2009, 21:54:25 EST by Fiona Krohn on behalf of School of Mathematics & Physics