Conjugated Polarizability Potential of Conjugated Alkenes

Based on the conjugated polarization theory，it is expressed as the conjugated polarizability potential （CPP）that the discrepancy between the average electrostatic energy of dipolar state and the electrostatic energy of non-polar state in the conjugated polarizability procedure for the conjugated alkenes. The correlation between CPP and the energy of ultraviolet absorption maximum，and the correlation between the energy of frontier molecular orbital obtained by ab initio calculation of quantum chemistry and the energy of ultraviolet absorption maximum have been carried out for the conjugated alkenes. Both correlation equations show a similar estimated precision. Further， the contribution of alkyl polarizability effect to the stability of dipolar state for the alkyl substituted alkenes with the effective polarizability effect index（PEI（ef））was quantified. Relating the above two parameters CPP and PEI（ef）to the energy of ultraviolet absorption maximum of the substituted alkenes in a two-parameter expression with a good prediction ability was obtained：v=1.1746+5.0187CPP-0.43204PEI （ef），R=0.9995，s=0.0403，F=10853.28，n=23. The investigated results also indicate that it is less effective to reduce the energy of ultraviolet absorption maximum by means of increasing the alkyl substituent groups than lengthening the conjugated backbone chain in the conjugated alkenes.