| The fundamental electronic spectroscopy of some simple free base porphyrins and metalloporphyrins were investigated. The goal was to elucidate the excited electronic states, vibrational states, dipole moments, triplet states lifetime and thermodynamic data.;High resolution Stark effect measurements on the S1 ← S0 (pipi*) origins of cis-isobacteriochlorin (cis-H2iBC), zinc chlorin (ZnCh), platinum chlorin (PtCh), magnesium chlorin (MgCh), magnesium isobacteriochlorin (MgiBC) and palladium isobacteriochlorin (PdiBC) in single crystals of n-octane at 4.2K are reported. The change in dipole moments (Deltamuge) are as follows: cis-H2iBC, 1.32 +/- 0.08D, metalloporphyrins, 0.20 +/- 0.04 D. Ground state dipole moments (mug) were determined by dielectric constant measurements of free base chlorin (H2Ch/benzene) solutions (H2Ch, mu g = 2.93 +/- 0.08D), MgCh/benzene solutions (MgCh, mug = 2.26 +/- 0.08 D) and solvatochromic shift data of cis-H2iBC (mug = 0.35 +/- 0.01 D) and trans-H2iBC (mu g = 2.16 +/- 0.05 D). The change in dipole moments were combined with the respective ground state dipole moments to calculate the excited state dipole moments (mue): H2Ch (mue = 2.68 +/- 0.08 D), cis-H2iBC (mue = -0.97 +/- 0.01 D), trans-H2iBC (mue = 3.51 +/- 0.05 D) and MgCh (mue = 2.59 +/- 0.08 D).;High resolution, single site emission and absorption spectra of ZnCh, PtCh, MgCh, MgiBC, PdiBC, octaethylporphin (H2OEP), zinc octaethylporphin (ZnOEP) and palladium octaethylporphin (PdOEP) in n-octane matrices at 7K are reported. Both the Q and Soret band origins have been investigated. The vibrational frequencies of the ground and four lowest energy pipi* singlet states were determined from emission and excitation spectra, respectively. The Qy regions consist of intense narrow origin bands followed by relatively weak, but orderly vibrational structure. The Qx regions of these metalloporphyrins do not have clear origins and exhibit complex vibrational structures. In the Soret regions, the two pipi* origins are usually clearly identifiable and some vibrational structure was also observed, except for PdiBC, H2OEP and ZnOEP.;Phosphorescence spectra of PdiBC, PdOEP, and PdOECh in n-octane Shpolskii matrices obtained at liquid nitrogen temperature are reported. The lifetime of triplet states (T1 → S0) at 77 K are PdiBC; 2.2 +/- 0.1 msec, PdOEP; 11.2 +/- 0.2 msec and PdOECh; 2.5 +/- 0.1 msec.;The planarity of metal chlorins in n-octane solutions were investigated and all of the metal ions of chlorins derivatives except the magnesium ion, showed strong indication of planarity. In another set of experiments we found that zinc chlorin tends to dimerized in n-octane solution and it's dimerization is temperature dependent. The DeltaH of dimerization was to be determined to be -17.49 +/- 0.2 KJ/mol, DeltaG = -27.9 +/- 0.2 KJ/mol and DeltaS = 49.12 +/- 0.2 J/mol. |
