69
trum is produced as a weighted sum of component RoA spectra of the individual
stable conformers, usually calculated according to the Boltzmann distribution. At
this point, the simulated RoA spectrum can be compared with the measured one
and analysed in a way appropriate to the application.
As a simple example of the calculation of RoA spectra we present our previous study of two bicyclic monoterpenes, 2- and 3-carene (Scheme 1), which occur
naturally in plants. delta-carene (3-carene), a major component of pine essential oil,
has several biological activities such as anti-inflammatory [63], antibacterial [64],
antifungal [65], inhibitory activity for acetylcholinesterase [66] and also anabolic
activity in bone metabolism [67]. the experimental RoA spectra of 2- and 3-carene
was reported in 1970s [68] but to the best of our knowledge RoA calculations had
not been reported in the literature previously.
Scheme 1 Chemical structure of 2- and 3-carene
Exploration of the conformational space of (+)-3-carene by dFt calculations with
the B3LYP functional and aug-cc-pvtZ basis set shows that only one conformer
of that compound is stable in the gas phase at 298.15 K and its structure is presented in Fig. 4.3. Additionally, in Fig. 4.3 the optimized geometry of its enantiomer
(−)-3-carene is presented.
Fig. 4.3 optimized geometries (dFt/B3LYP/aug-cc-pvtZ, gaussian ’09) of two enantiomers:
(−)-3-carene (a) and (+)-3-carene (b)
4 Raman optical Activity of Biological Samples
trum is produced as a weighted sum of component RoA spectra of the individual
stable conformers, usually calculated according to the Boltzmann distribution. At
this point, the simulated RoA spectrum can be compared with the measured one
and analysed in a way appropriate to the application.
As a simple example of the calculation of RoA spectra we present our previous study of two bicyclic monoterpenes, 2- and 3-carene (Scheme 1), which occur
naturally in plants. delta-carene (3-carene), a major component of pine essential oil,
has several biological activities such as anti-inflammatory [63], antibacterial [64],
antifungal [65], inhibitory activity for acetylcholinesterase [66] and also anabolic
activity in bone metabolism [67]. the experimental RoA spectra of 2- and 3-carene
was reported in 1970s [68] but to the best of our knowledge RoA calculations had
not been reported in the literature previously.
Scheme 1 Chemical structure of 2- and 3-carene
Exploration of the conformational space of (+)-3-carene by dFt calculations with
the B3LYP functional and aug-cc-pvtZ basis set shows that only one conformer
of that compound is stable in the gas phase at 298.15 K and its structure is presented in Fig. 4.3. Additionally, in Fig. 4.3 the optimized geometry of its enantiomer
(−)-3-carene is presented.
Fig. 4.3 optimized geometries (dFt/B3LYP/aug-cc-pvtZ, gaussian ’09) of two enantiomers:
(−)-3-carene (a) and (+)-3-carene (b)
4 Raman optical Activity of Biological Samples