Density functional theory studies on the Raman and IR spectra of meso-tetraphenylporphyrin diacid.
The vibrational spectra of meso-tetraphenylporphyrin diacid (H4TPP2+) have been studied with the density functional theory. Raman and IR spectra of H4TPP2+ and its N-deuterated analogue (D4TPP2+) are measured and compared with the computational results. Complete assignments of observed IR and Raman bands were proposed on the bases of calculation results. The DFT calculations reproduce 140 observed fundamentals with the RMS 8.6 cm-1. The computational as well as the experimental results reveal that the saddle-distortion of porphyrin macrocycle for the diacid leads to a significant effect on its vibrational spectra. Especially, several out-of-plane skeletal modes, which were either unobserved or very weak in the Raman spectra of CuTPP and H2TPP, are activated in the Raman spectra of the diacids. In addition, enhancement for the Raman bands of phenyl CC stretching modes were observed and attributed to the conjugation effect of pi-systems of the phenyl and the porphyrinato macrocycles.
Xu
Lian-Cai
LC
Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, PR China.
Li
Zun-Yun
ZY
Tan
Wei
W
He
Tian-Jing
TJ
Liu
Fan-Chen
FC
Chen
Dong-Ming
DM
D000143:Acids / Q000737:chemistry*; D002725:Chloroform; D008956:Models, Chemical; D011166:Porphyrins / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014732:Vibration
D000143:Acids; D011166:Porphyrins; D012996:Solutions; C508866:meso-tetraphenylporphyrin diacid; D002725:Chloroform