Spectroscopic investigation of Tb(III) porphyrin in solid and solutions

Characteristic Q and S (Soret) bands of metal porphyrins in the visible and near ultraviolet region are assigned as excited S-1 singlet and the second excited S-2 states. Upper excited-state emission has been observed for var iety of diamagnetic metal porphyrins. In the paramagnetic systems emission depends on the position of CT, d- and f- excited states that could take par t in the porphyrin emission quenching. In some kinds of porphyrins with f-e lectron metals, TPPEr(III)dpm types, porphyrin emission depends on the ener gy of the triplet and singlet states of beta-diketone. The TPPTb(III)acac p orphyrin was obtained in the solid state. Its structure was earlier describ ed by different methods. Absorption, emission, IR and Raman spectroscopy we re used to characterize Tb(III) porphyrin in solid and solution. Absorption spectra were measured at room temperature, emission and excitation ones at 293 and 77 K. Correlation of the spectroscopic results in solids makes pos sible considerations about the role of solvent molecules in modifications o f the structure of porphyrin complex in solutions. (C) 2000 Elsevier Scienc e S.A. All rights reserved.