Correlation of structure and vibrational spectra of the
-alanine in the presence of water: an experimental
and density functional analysis
Michael W. Ellzy
*, James O. Jensen
, Hendrik F. Hameka
, Jack G. Kay
US Army Edgewood Research Development and Engineering Center, Aberdeen Proving Grounds, Aberdeen, MD 21010-5423, USA
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 10194, USA
Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA
Received 17 October 2002; received in revised form 30 December 2002; accepted 10 January 2003
Infrared vibrational spectra were collected along with the vibrational circular dichroism (VCD) spectra for the
-mannose and a-
-mannose as potassium bromide (KBr) pressed samples.
-alanine dissolved in water was also measured and compared against the spectra resulting from KBr
pressed samples. The experimental data were compared against the ab initio B3LYP/6-31G* optimized geometry. The
zwitterion structure of a-
-alanine was stabilized by the addition of water molecules. Computationally, b-
was studied and resulting expected VCD bands assigned. We present the molecular structures resulting VCD spectra
and infrared vibrational spectra from experimentation as compared with the computed results.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Zwitterion; a-
-Mannose; Vibrational circular dichroism; Ab initio; Density
functional ﬁeld theory; Moller Á
Plesset second-order perturbation theory; Becke 3 Lee Young Parr; Gaussian 98
Ab initio analysis is a useful approach for the
evaluation of biological and chemical compounds.
An important aspect of this computational tech-
nique is the ability to determine structural details
for the analyte under investigation. Extending the
application of ab initio analysis is the ability to
apply vibrational information towards the inter-
pretation of analyte conformation. For chiral
compounds, precise stereo-chemical information
is obtained with the application of vibrational
circular dichroism (VCD) in conjunction with ab
initio analysis. The approach has been applied to
conformational analysis of various carbohydrates
 dissolved in carbon disulfide. Our current
interest in VCD is the potential to use the
* Corresponding author. Tel.: '
1-410-436-3957; fax: '
E-mail address: firstname.lastname@example.org (M.W.
Spectrochimica Acta Part A 59 (2003) 2619 Á
1386-1425/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.