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Electronic Circular Dichroism Spectroscopy of 1‐( R )‐Phenylethanol: The “Sector Rule” Revisited and an Exploration of Solvent Effects
Author(s) -
Macleod Neil A.,
Butz Patrick,
Simons John P.,
Grant Guy H.,
Baker Christopher M.,
Tranter George E.
Publication year - 2004
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1560/lm77-umav-80ef-vywc
Subject(s) - chemistry , polarizable continuum model , dihedral angle , polarizability , solvation , ab initio , circular dichroism , solvent effects , computational chemistry , cyclohexane , molecular dynamics , solvation shell , density functional theory , dielectric , solvent , molecule , crystallography , hydrogen bond , organic chemistry , physics , optoelectronics
The sensitivity of the electronic circular dichroism (ECD) of a chiral molecule to structural and environmental changes has been investigated using 1‐( R )‐phenylethanol (1‐PE) as the benchmark solute and cyclohexane and water as the trial solvents. Rotatory strengths associated with the π → π* ( 1 L b ) electronic transition have been calculated ab initio for: (a) isolated 1‐PE, as a function of the dihedral angles within its chiral side chain and between the side chain and the aromatic ring: these confirm the validity of the empirical “sector rule” but with the signs reversed; (b) the singly and doubly hydrated clusters of 1‐PE, isolated in the gas phase; (c) 1‐PE and its singly and doubly hydrated clusters embedded in a polarizable dielectric continuum; and (d) 1‐PE in an aqueous solution interacting with the local hydration shell and with the polarizable dielectric continuum, using averaged solute structures computed from the fluctuating solute and solvent configurations generated via molecular dynamics simulations. The ab initio calculations (conducted with GAUSSIAN 98) employed configuration interaction singles (CIS) or time‐dependent density functional theory (TD‐DFT) procedures using basis sets of double‐ and triple‐zeta quality. The results have been related to experimental observations and discussed in terms of changes in the molecular geometry and solvent‐induced perturbations.