Nitrobenzene method: A keystone in meso-substituted halogenated porphyrin synthesis and applications

This review article briefly describes the available synthetic approaches for meso-arylporphyrins giving particular emphasis for one-pot nitrobenzene and nitrobenzene/NaY methods regarding the synthesis of meso-halogenated arylporphyrins. The review also describes the relevant applications of these halogenated porphyrins and their metalloporphyrin counterparts, prepared via nitrobenzene method, as photosensitizers for therapy (PDT and PDI), diagnostic (molecular contrast agents) and also for catalytic oxidation and CO2 cycloaddition reactions to epoxides.

A spectrophotometric and thermodynamic study of the sitting-atop complex formation from reaction between free base meso-tetraarylporphyrins and zirconyl nitrate in chloroform solution

The sitting-atop complexation of meso-tetraarylporphyrins and its para-substituted derivatives (H(2)t(4-X)pp, X:H, Br, Cl, CH(CH(3))(2), OCH(3), CH(3)), as electron donors, with zirconyl, as an electron acceptor, have been investigated spectrophotometrically in chloroform. The mole ratio studies based on physicochemical techniques were employed clearly and revealed the formation of 1:1 sitting-atop complexes which was confirmed by UV-vis, (1)H NMR and IR spectroscopic data. The value of the formation constant was estimated for each complex using a nonlinear optimization of the complex absorbance vs. mole ratio data by package KINFIT. The results showed that the stability of these complexes decreases with the temperature enhancement. Thermodynamic parameters, DeltaG degrees , DeltaH degrees and DeltaS degrees , of the SAT complexes have been determined from the temperature dependence of formation constants by Van't Hoff equation. Also, the influence of the substituents of the aryl rings in H(2)t(4-X)pp on the stability of the SAT complexes is discussed.

Spectrophotometric studies of the thermodynamics of sitting-atop complexation between free base meso-tetraarylporphyrins and titanium(IV) chloride

Titanium(IV) chloride reacts with free base meso-tetraarylporphyrin and its ortho, meta and para-substituted derivatives (H(2)T(X)PP; X: OCH(3), CH(3) and Cl) for formation of sitting-atop (SAT) complexes, [TiCl(4)(H(2)T(X)PP)]. The computer fitting of the variation of the absorbance versus mole ratio by KINFIT program was used for calculation of the formation constants of these complexes in chloroform. Thermodynamic parameters, DeltaG degrees , DeltaH degrees , DeltaS degrees , have been determined and the influence of the temperature and the substituted aryl groups (electronic and steric effects) in the free base porphyrins on the stability of the SAT complexes was studied.