Our research program centers on the study of chiral fluids and interfaces. Current projects are aimed at providing
molecular level descriptions of
Chirality transfer processes in the bulk
Chirality transfer processes at interfaces
Chiral discrimination and solvation of chiral stationary phases
Chirality and liquid crystals
Self-selectivity and racemic fluids
Each of these research themes is discussed below. In tackling these research areas, we are often required to modify existing approaches or to
develop new methodologies and algorithms. Our methods include
Molecular dynamics simulations for chiral fluids and interfaces
Integral equation theories for chiral fluids
Models for liquid crystal mesogens and chiral surfaces
Polarizable fluid models
Parallel programming algorithms for simulations of chiral fluids and interfaces
Our approach is to target specific questions relevant in chiral processes or systems - chiral recognition in chiral
chromatography for example - and devise an approach for addressing the issues. Because enantiomeric differences
are subtle, this usually means that attention to detail is crucial. We often begin with extensive
ab initio
calculations to develop accurate molecular models and continue with simulations or theories. For the latter, we use
our own codes and perform exhaustive computations on high performance computing facilities across Canada.
Top Five
My favorite five publications from our group are listed here. I've chosen them based on my overall impression
of their importance - sometimes it's the impact on understanding of chirality and sometimes it's the importance of the
methods developed. Click on publications on the sidebar to see a full publication list.
A molecular dynamics study of chiral recognition for the Whelk-O1 chiral stationary phase,
C. Zhao, N. M. Cann, Analytical Chem., 80, 2426-2438(2008).
Polarizable and flexible model for ethanol,
S. Wang, N. M. Cann, J. Chem. Phys., 126, 214502-1 - 214502-23(2007).
Discrimination in racemates of small chiral molecules,
J. Vatamanu, E. Cressman, N. M. Cann, Mol. Phys., 101, 3085-3102(2003).
Integral equation theories for orientationally ordered fluids,
I. Paci, N. M. Cann, J. Chem. Phys., 119, 2638-2657(2003).
The solvation of phenylglycine- and leucine-derived chiral stationary phases: A molecular dynamics simulation study,
S. Nita, N. M. Cann, J. Phys. Chem. B, 112, 13022-13037(2008).
Chirality transfer processes in the bulk
This project is aimed at understanding the process by which chiral solutes transfer their
chirality to surrounding solvent. The picture below illustrates the general concept with the green area
representing a zone where solvent has acquired some chirality. Our goal is
to understand how far this region extends, in what areas around the solute is it most important,
and how it varies between different solutes and different solvents. Finally, we hope to understand
and predict spectroscopic contributions from nearby "chiral" solvent and to understand whether this
process could impact reaction mechanisms.
Chirality transfer processes at interfaces
A solvent near a chiral surface will respond to many chiral molecules on the surface. In other words, there is the
potential for a collective effect on the solvent. This project is
aimed at understanding how the presence of multiple chiral molecules impacts the nearby solvent. Our focus is on
surfaces relevant to chiral chromatography where solvent is known to dramatically impact selectivity.
Chiral discrimination and solvation of chiral stationary phases
Chiral stationary phases offer a rapid, cost-effective, and commonly used means of separating enantiomers.
However, the choice of a particular stationary phase for a given racemate is made largely based on empirical
information - whether the CSP has separated similar enantiomers. Because of this, a trial-and-error process
can result. Our objective is to simulate realistic model chiral interfaces to predict separation factors, to directly
examine the selective mechanisms at play, and to suggest new stationary phases or particular solvents.
The picture on the left shows a snapshot from a simulation of the Whelk-O1 chiral stationary phase as it
discriminates between S- and R-styrene oxide. The figure on the right hand side shows several docking modes
for S- and R-naproxen (marketed as Aleve) on Whelk-O1.
Chirality and liquid crystals
Some chiral dopants, when added to an achiral liquid crystal host, can induce significant chirality
into the phase. The extent of this chirality transfer and its dependence on host and dopant characteristics
have been the subject of many experimental studies. Simulations of liquid crystals are challenging but, with
current computing resources, realistic representations of mesogens are now possible. Our objective is to
fully characterize the liquid crystal phases with and without the chiral dopants. The snapshots below show
2-(4-butyloxyphenyl)-5-octyloxypyrimidine(left) and 5-(4-butyloxyphenyl)-2-octyloxypyrimidine(right) at 365K and
370K, respectively. Smectic layers are clearly evident in the snapshots.
Self-selectivity and racemic fluids
UNDER CONSTRUCTION!
Molecular dynamics simulations for chiral fluids and interfaces
Integral equation theories for chiral fluids
Models for liquid crystal mesogens and chiral surfaces
Polarizable fluid models
Parallel programming algorithms for simulations of chiral fluids and interfaces
