Resonance Raman (RR) scattering from intact pea phytochrome was observed in resonance with the blue band at ambient temperature. The relative populations of the red-light-absorbing form (Pr) and far-red-light-absorbing form (Pfr) under laser illumination were estimated from the absorption spectra. The most prominent RR band of Pr obtained by 364-nm excitation under 740-nm pumping exhibited a frequency shift between H2O and D2O solutions, but that of Pfr obtained by 407-nm excitation under 633-nm pumping did not, indicating a distinct difference in a protonation state of their chromophores. Since the protonation level of a whole molecule of intact phytochrome remains unchanged between Pr and Pfr, this observation indicates migration of a proton from the chromophore of Pr to the protein moiety of Pfr. As model compounds, octaethylbiliverdin (OEBV-h3), its deuterated and 15N derivatives, and their protonated forms were also studied with both RR and 1H and 15N NMR spectroscopies. The RR spectrum of the protonated form, for which the protonation site was determined to be C-ring pyrrole nitrogen by NMR, displayed a deuteration shift corresponding to that of Pr, suggesting a similar protonated structure for the pyrrolic rings of Pr. The RR spectral difference between OEBV-h3 and OEBV-d3 and that between H2O and D2O solutions of Pfr suggested that the N-H protons of the A-, B-, and D-rings of intact phytochrome are replaced with deuterons in D2O. A role of the 7-kDa segment of phytochrome is discussed on the basis of RR spectral differences between the intact and large phytochromes.

Time-resolved resonance Raman spectra are reported for the free-base octaethylporphyrin ((OEP)H2) and its meso-deuterated ((OEP-d4)H2), pyrr~le-~~N-substituted ((OEP-I5N4)H2), ethyl-deuterated ((OEP-d28)H2), and their imino-d2 isotopomers ((OEP)D*) in the lowest excited singlet (SI, '(nn*)) and triplet states (TI, 3(nn*)) as well as for those in the ground state (SO). Both the totally symmetric and nonsymmetric modes were resonance-enhanced in Raman intensity for the SI and TI states, and their vibrational modes are interpreted on the basis of the observed polarization properties, isotopic frequency shifts, and theoretical assignments reported for (OEP)H:! and (0EP)Ni in the ground electronic state. As a common feature for the SI and TI states, a few polarized Raman bands sensitive to the peripheral ethyl-deuteration were enhanced around 1200 cm-I, similar to the SO state, suggesting the existence of the un-n hyperconjugation between the macrocycle and ethyl groups in the SI and TI states, too. In the SI state, the C,C, antisymmetric stretching mode with ap (anomalously polarized) polarization, which corresponds to VI9 of the SO state, was resonance-enhanced at the frequency (1534 cm-') downshifted by 54 cm-I from that in the ground state (1588 cm-I). This indicates the presence of SI-& vibronic coupling. Iflthe TI state, however, no ap band was observed in the 1600-1500 cm-I region, but instead, a depolarized band with complicated and unresolved structures was noticeably enhanced around 1440-1400 cm-I and dp (depolarized) bands were generally broad. This suggests the presence of another vibronic mechanism, presumably pseudo Jahn-Teller effects between 3B3u and 3B2u states.As a possible mechanism of band broadening in the TI state, unresolved tunnel splitting between N-H tautomers is suggested.

The synthesis of the first fluorine-containing iron porphycenes, 2,7,12,17-tetraethyl-3,6,13,16-tetrakis(trifluoromethyl)porphycenatoiron(III) chloride [FePc(EtioCF(3))]Cl and its micro-oxo dimer [FePc(EtioCF(3))](2)O and their characterizations are reported. The crystal structure of [FePc(EtioCF(3))](2)O displays a severe saddled distortion of the porphycene framework due to the steric and electronic effects of the CF(3) substituents. The oxidation and reduction potentials for the micro-oxo dimer are significantly more positive compared to those observed for the reference micro-oxo dimer of the iron porphycenes and porphyrins having no electron-withdrawing substituent. Moreover, the (1)H and (19)F NMR spectra of [FePc(EtioCF(3))](2)O demonstrated that the micro-oxo dimer is readily converted into the monomeric ferrous complex in pyridine-d(5) through autoreduction for 1 day, although the reduction of the reference iron porphycenes and porphyrins are not observed in pyridine. These results indicate that the trifluoromethylated iron porphycene is a highly electron-deficient complex with a pyrrolic macrocycle ligand.