TY  - JOUR
ID  - pittir17986
UR  - http://d-scholarship-dev.library.pitt.edu/17986/
IS  - 34
A1  - Florio, GM
A1  - Christie, RA
A1  - Jordan, KD
A1  - Zwier, TS
Y1  - 2002/08/28/
N2  - The hormone melatonin (N-acetyl-5-methoxytryptamine) is an indole derivative with a flexible peptide-like side chain attached at the C3 position. Using a combination of two-color resonant two-photon ionization (2C-R2PI), laser-induced fluorescence excitation (LIF), resonant ion-dip infrared spectroscopy (RIDIRS), fluorescence-dip infrared spectroscopy (FDIRS), and UV-UV hole-burning spectroscopy, the conformational preferences of melatonin in a molecular beam have been determined. Three major transamide conformers and two minor cis-amide conformers have been identified in the R2PI spectrum and characterized with RIDIRS and FDIRS. Structural assignments are made using the infrared spectra in concert with density functional theory and localized MP2 calculations. Observation of cis-amide melatonin conformers in the molecular beam, despite the large energy gap (?3 kcal/mol) between trans- and cis-amides, is striking because there are at least nine lower-energy trans-amide minima that are not detected. The implications of this observation for cooling and trapping conformational population in a supersonic expansion are discussed.
JF  - Journal of the American Chemical Society
VL  - 124
SN  - 0002-7863
TI  - Conformational preferences of jet-cooled melatonin: Probing trans- and cis-amide regions of the potential energy surface
SP  - 10236 
AV  - public
EP  -  10247
ER  -