Study On The UV Spectra Absorption Of α,ω-di-substituted Phenylpolyenes

Establishment of the quantitative relationship between the molecular structure and theoptical properties of compounds is the basis of designing and synthesis the optical functionalmaterials. The α,ω-diphenylpolyene derivatives(DPPs) is an important kind of organicconjugated compouds, which has attracted a great deal of interest for their good opticalproperties. Chemist have done many researches on their nonlinear optics and fluorescenceemission spectra. As we known, nonlinear optics and fluorescence emission spectra ofcompounds are the performance of molecules excited by absorption light, thus understandingthe UV-vis absorption spectral change rules of DPPs also has important theoreticalsignificance and practical value.DPPs(p-X-Ph(CH=CH)n-Ph-Y-p) is a series compouds with substituent typles andrepeating unit number(n) varying. In this work, we are focus on the rules of UV of DPPswhen the two factors both changed.This thesis involves three aspects as follows:(1)28samples of DPBs (p-X-Ph(CH=CH)2-Ph-Y-p) and11samples of DPHs(p-X-Ph(CH=CH)3-Ph-Y-p) have been synthesized. Their stucture are determined with IR and1H NMR, and the corresponding UV absorption wavelengths (λmax) are measured inanhydrous ethanol.(2) Collecting and organizing UV data of some relative DPPs reported, then combinewith the UV date masured in this paper to form the data set.(3) The effects of substituents and conjugated chain length on the UV spectra ofα,ω-di-substituted phenylpolyenes1have been investigated. The result shows: the maximumwavelength energy of the title compounds are mainly affected by both of the substituentexcited-state parameters and polar parameters where one substituent is changed, and theexcited-state parameters play a leading role, while the polar parameters effected more for theDPPs including strong electron-donating group N(Me)2; when two substituebts changed, the maximum wavelength energy correlate with the substituent interaction item, and the polarparameters play an unignorable role; when the substituents and conjugated chain length bothchanged, the UV spectra of DPPs are mainly affected by both substituent excited-stateparameters and maximum wavelength energy of the parent molecule, but these two factors arenot independent each other, in which the action of substituent is governed by the parentmolecular absorption energy. In case of the compounds containing group NO2or NH2, theinfluence of interaction of polarity parameters on the maximum wavelength energy must alsobe considered. In addition, also the exploration was made for the quantifying correlation ofultraviolet absorption maximum wavelength energy with the conjugated polarizabilitypotential CPP replacing the parent molecular absorption energy, and a good QSPR correlationequation cotained3parameters was abtained. This study provide a new understanding for themolecular conformation on spectral properties of DPPs.