Volumetric properties of tetraphenylporphine, their metallo-complexes and some substituted tetraphenylporphines in benzene solution

Abstract

Densities, apparent molar volumes and partial molar volumes of benzene solutions of tetraphenylporphine, H₂TPP, tetraphenylporphine metallo-complexes, MTPP (where M=Ni,Cu,Zn,Pd,Ag, and Cd), and some substituted tetraphenylporphines H₂T(i-R)PP (where i=2–4 and R=−Cl,−CH₃,−OCH₃) H₂T(i-F)PP (where i-2,3), H₂T(3-Br)PP, and H₂T(3-I)PP were determined at 25°C. It was found that the partial molar volumes of the studied compounds correlate linearly with the first ionization potential of the corresponding metal atom. The calculated values of the surface and volume accessible to the solvent, and the solvent-excluded volume for different conformations of H₂TPP, were compared with experimental data. The volume per molecule for different crystalline forms of H₂TPP and MTPP were compared with the partial molar volumes of the corresponding compounds in benzene solutions. The correlation between the partial molar volumes of H₂T(3-R)PP and their Van der Waals volumes are presented for R=−H, −F,−CH₃,−Cl,−Br,−OCH₃, and −I. The experimental data are rationalized in terms of differences in the conformational states of the molecules.