Excited-state absorption and ultrafast relaxation dynamics of protoporphyrin IX and hemin

Abstract

The transient evolution of protoporphyrin IX (PPIX) and hemin following the Soret band excitation was measured in the 410-600 nm spectral region with sub-picosecond time resolution. In PPIX the relaxation pathway was characterized in the femto- and picosecond time scale by two processes with time constants of 350 fs and ~6 ps, describing the evolution of the system through internal Q(y) → Q(x) conversion and vibrational relaxation and cooling in the Q(x) state. The lifetime of the Q(x) state was found to be 10.4 ns by time resolved fluorescence measurements. In hemin, the ground state is completely recovered in tens of picoseconds through pathways involving CT and (d,d) states. The experimentally observed vibrational dynamics is mainly due to "hot" ground state transitions.

Investigation of Morphology‐Controlled Ultrafast Relaxation Processes of Aggregated Porphyrin

“…[32] Gelini et al have investigated the energy relaxation dynamics of H 2 P, PPIX and hemin using femtosecond transient absorption spectroscopy. [33] The exciton relaxation dynamics in 1D porphyrin J-aggregates have been reported. [34] Bozio and co-workers studied the excitonic interactions of monomeric and J-aggregated form of water-soluble H 4 TPPS 2À by transient absorption and two-photon absorption spectral analysis.…”

Structure and activity of tryptophan-rich TSPO proteins

“…To examine the possible roles of these residues in PpIX degradation, we compared the reaction for wild-type (WT) with reactions for the W138F, W51F, W51F/W138F variants, and we also tested A142T because of its relation to the polymorphic variation at the analogous position (A/T147) in Homo sapiens TSPO1 ( Hs TSPO1). We used the sensitive PpIX fluorescence spectrum (26, 27) to monitor the changes.…”

Photophysical properties and singlet oxygen generation ofmeso-iodinated free-base corroles

“…Second, VC usually presents a dependence at various probe wavelength, band shiing and narrowing. 36,37 We observed an apparent rearrangement at the Q bands bleaching at about 611 to 650 nm, from 5 to $100 ps. The Q band bleachings at 610 nm and 636 nm decrease and the 650 nm SE rises gradually.…”

“…29) and 6 ps for protoporphyrin IX (PPIX). 37 Bangal's group found a 105 ps relaxation for 5,10,15,20-meso-tetrakis penta-uorophenyl porphyrin (H 2 F 20 TPP). 39 They attributed it not only a VC lifetime but also an excited state conformational relaxation.…”