Intramolecular charge delocalization and nonlinear optical properties of Methyl 3-(4-methoxy phenyl) prop-2-enoate from vibrational spectra
✍ Scribed by D. Sajan; I. H. Joe; J. Zaleski; V. S. Jayakumar
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 212 KB
- Volume
- 2
- Category
- Article
- ISSN
- 1612-2011
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✦ Synopsis
The density functional computations of MMP are
performed at B3LYP/6-31G (d,p) level to derive equilibrium
geometry, vibrational wavenumbers and intensities, and first
hyperpolarizability. Large NLO efficiency predicted for the first
time in this new class of compounds has been confirmed by powder
efficiency experiments. DFT calculation reveals that endocyclic
angle at the junction of the propenoate group and the phenyl ring
is decreased from 120° by 2.5°, whereas two
neighbouring angles around the ring are increased by 2.1°
and 1.2° respectively, associated with intramolecular
charge transfer interaction. The vibrational spectra confirm the
charge transfer interaction between -COOCH~3~ group and phenyl
ring through the ethylenic bridge with simultaneous infrared and
Raman activation of C~7~=C~18~ stretching and ring modes 8
and 19. The large intensity differences observed between 8__a__
and 8__b__ modes in both IR and Raman spectrum due to the algebraic
difference of the electronic effects of the substitutents have
been discussed. The charge transfer interaction between -COOCH~3~
group and phenyl ring through the ethylenic bridge resulting in
π-electron cloud movement from donor to acceptor can make the
molecule highly polarized and must be responsible for the NLO
activity of MMP.