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RESEARCH PRODUCT

Intramolecular charge delocalization and nonlinear optical properties of Methyl 3-(4-methoxy phenyl) prop-2-enoate from vibrational spectra

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description

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 -COOCH3 group and phenyl ring through the ethylenic bridge with simultaneous infrared and Raman activation of C7=C18 stretching and ring modes 8 and 19. The large intensity differences observed between 8a and 8b 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 -COOCH3 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.