Spectral and Luminescent Properties of Some Porphyrin Compounds in Different Electronic States

meso‐Aryl Phenanthroporphyrins: Synthesis and Spectroscopic Properties

“…Virtually identical emission bands are observed for 5 a H 2 2+ – 5 h H 2 2+ at (846±12) nm with Stokes shifts of (530±70) cm −1 . The fluorescence quantum yields are between 150–250 % higher than those of the corresponding free bases, as has been reported previously for other highly sterically hindered porphyrins such as DPP (DPPH 2 2+ : Φ f =7×10 −3 , τ f =0.33 ns in CHCl 3 ) 36…”

“…This suggests that the emissive state is rapidly quenched by intramolecular processes. The fluorescence quantum yield and lifetime data are of the same order of magnitude as those found for other highly distorted porphyrins such as dodecaphenylporphyrin34–36 (DPP): Φ f =2×10 −3 , τ f =0.095 ns in CHCl 3 36. As is the case with DPP, the relatively low emissivity of these compounds can be ascribed to the high degree of nonplanarity,13 which facilitates intersystem crossing and internal conversion, and the growing influence of internal conversion as a function of the shift of the emission band into the NIR region due to the energy‐gap rule 37.…”

“…The fluorescence quantum yield and lifetime data are of the same order of magnitude as those found for other highly distorted porphyrins such as dodecaphenylporphyrin [34][35][36] (DPP): F f = 2 10 À3 , t f = 0.095 ns in CHCl 3 . [36] As is the case with DPP, the relatively low emissivity of these compounds can be ascribed to the high degree of nonplanarity, [13] which facilitates intersystem crossing and internal conversion, and the growing influence of internal conversion as a function of the shift of the emission band into the NIR region due to the energygap rule. [37] The increase in the rate constant of nonradiative deactivation [38] observed for the 4-halogeno compounds, 2.4 (5 c) < 3.9 (5 d) < 4.7 (5 e) < 7.0 10 9 s À1 (5 f), is consistent with an internal heavy-atom effect that has been reported previously for porphyrins.…”

“…free bases, as has been reported previously for other highly sterically hindered porphyrins such as DPP (DPPH 2 2 + : F f = 7 10 À3 , t f = 0.33 ns in CHCl 3 ). [36] The B3LYP geometry optimization for 5 iH 2 2 + (Table 3) predicts that the electrostatic repulsion introduced by the two additional protons on the inner ligand perimeter leads to a further deepening of the saddled structure. Similar effects have previously been reported for tetraphenylporphyrinoids with the meso-phenyl rings tilting into the plane of the inner perimeter of the p system.…”

Integration of Partial Least Squares Regression and Hyperspectral Data Processing for the Nondestructive Detection of the Scaling Rate of Carp (Cyprinus carpio)

“…Figure 2b-d shows the original mean spectra of the different regions with different scaling rates, respectively. All illustrated an obvious absorption peak around 420 nm, which might be caused by the absorption of porphyrin compounds in the visible region [46]. Furthermore, several absorption peaks were observed in the range of 500-600 nm, which might be due to the existence of metmyoglobin [47].…”