[Study on structure and spectra of 1,4-bis[(p-methoxyphenoxy) carbonyl]].

Theoretical studies on 1,4-bis [(p-methoxyphenoxy) carbonyl] and ramification were carried out using the density functional theory at B3LYP/6-31+G* level to obtain optimized equilibrium structure, vibrational spectra and electronic spectra. The calculation results indicate that the carbon and oxygen (in the ester group) come into being different large pi bonds with the benzene circles because of place blocking and conjugate effect. On this basis, the first excited state electronic transition energy was calculated by time-dependent density function theory. The calculated results show that the largest absorption spectra of the title compounds were obtained from the pi --> pi* electron transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital. And lambda(max) was obtained in 370-384 nm, belonging to the UV absorption area. The computed results show that the lateral substitutent of 1,4-bis [(p-methoxyphenoxy) carbonyl] has little effects on molecular structure. Because of place blocking, the dihedral angle between benzene (1) and benzene (2) augments 3 degrees-4 degrees. The introduction of the lateral substitutents has effects on vibrational spectra. The results showed that with the introduction of hydroxy the difference between E(HOMO) and E(LUMO) of the compound becomes small. While lambda(max) becomes large. Meanwhile, the difference between E(HOMO) and E(LUMO) reduces by 0.120 9 eV with the introduction of fluorin. This causes the biggest absorption wavelength to red shift 14 nm.