[The structure and properties of metal-free 1, 8, 15, 22-tetrakis (3-pentyloxy) phthalocyanine complex and study of its IR spectra].

Density functional theory calculations were carried out to study the molecular structure, molecular orbital, atomic charge, and infrared spectra of metal-free 1, 8, 15, 22-tetrakis(3-pentyloxy) phthalocyanine using B3LYP method with the 6-31G (d) basis set. The optimized molecular geometry is in good agreement with the result from X-ray deterimination, and the differences between the bond lengths from calculation and X-ray crystallography structure for the framework of phthalocyanine are less than 0.002 nn. It was also found that there is a good consistency between the calculated and experimental IR data. The calculated structure and IR spectra were fairly compared with the X-ray crystallography structure and experimental IR spectra to verify the reliability of employed B3LYP method and 6-31G(d) basis set. It is worth noting that the 3-pentyloxy groups at the alpha position have significant influence on the structure and properties of metal-free pthalocyanine, for example, both the energies of HOMO and LUMO increase, however, the gap between HOMO and LUMO decreases, which results in the decrease of the 1, 8, 15,22-tetrakis(3- pentyloxy)phthalocyanine stability. The important peaks in the IR spectra were also assigned and analyzed in detail according to the calculations.