Electronic Spectroscopy, Photophysical Properties, and Emission Quenching Studies of an Oxidatively Robust Perfluorinated Platinum Porphyrin
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- 作者：Siu-Wai Lai ; Yuan-Jun Hou ; Chi-Ming Che ; Hei-Leung Pang ; Kwok-Yin Wong ; Chi K. Chang ; and Nianyong Zhu
- 刊名：Inorganic Chemistry
- 出版年：2004
- 出版时间：June 14, 2004
- 年：2004
- 卷：43
- 期：12
- 页码：3724 - 3732
- 全文大小：199K
- 年卷期：v.43,no.12(June 14, 2004)
- ISSN：1520-510X
文摘
The highly electron-deficient, 
-octafluorinated meso-tetrakis(pentafluorophenyl)-porphyrin (H2F28TPP) was metalatedwith platinum to afford the oxidatively robust luminophore [PtF28TPP], and its X-ray structure shows that the porphyrincore exists in a slightly saddle-shaped conformation. The absorption spectrum of [PtF28TPP] in CH2Cl2 displays anear-UV Soret band (B) at 383 nm (
= 2.85 × 105 dm3 mol-1 cm-1) and two visible Q(1,0) and Q(0,0) bands at501 ( = 1.45 × 104 dm3 mol-1 cm-1) and 533 ( = 1.36 × 104 dm3 mol-1 cm-1) nm, respectively. Theseabsorption bands of [PtF28TPP] are blue-shifted from those in [PtF20TPP] (390, 504, and 538 nm, respectively) and[PtTPP] (401, 509, and 539 nm, respectively). Excitation of [PtF28TPP] (complex concentration = 1.5 × 10-6 moldm-3) in dichloromethane at the Soret or Q(1,0) or Q(0,0) band gave a phosphorescence with peak maximum at650 nm (lifetime = 5.8 
s) and a weak shoulder at 712 nm. Both the emission lifetime and quantum yield vary withsolvent polarity, and plots of 
versus EK and 
versus EK (where EK is the empirical solvent polarity parameterbased on the hypsochromic shift of the longest wavelength absorption of the [Mo(CO)4{(C5H4N)HC=NCH2C6H5}]complex with increasing solvent polarity; see: Kamlet, M. J.; Abboud, J. L. M.; Taft, R. W. Prog. Phys. Org. Chem.1981, 13, pp 485-630) show linear correlation, indicating that the emission is sensitive to the local environment/medium. Electrochemical studies on [PtF28TPP] by cyclic voltammetry showed no porphyrin-centered oxidation atpotential 
1.5 V versus Ag/AgNO3, demonstrating that [PtF28TPP] is more resistant toward oxidation than [PtF20TPP] (E1/2 = 1.33 V) and [PtTPP] (E1/2 = 0.97 V). The porphyrin-centered reduction of [PtF28TPP] occurs at -0.75and -1.18 V, which is anodically shifted from those at -1.06 and -1.55 V in [PtF20TPP], and -1.51 V in [PtTPP],respectively. The excited-state reduction potential of [PtF28TPP] is estimated to be 1.49 V versus Ag/AgNO3. Over97% of the emission intensity of [PtF28TPP] was retained after irradiation with a high power mercury arc lamp (500W) for 14 h, compared to 90% and 12% for [PtF20TPP] and [PtTPP], respectively; hence, [PtF28TPP] exhibitssuperior photostability. Quenching of the emission of [PtF28TPP] by oxygen, alcohol, catechol, and butylaminereveals that [PtF28TPP] is an oxidatively robust material with medium-sensitive photoluminescence properties.
-octafluorinated meso-tetrakis(pentafluorophenyl)-porphyrin (H2F28TPP) was metalatedwith platinum to afford the oxidatively robust luminophore [PtF28TPP], and its X-ray structure shows that the porphyrincore exists in a slightly saddle-shaped conformation. The absorption spectrum of [PtF28TPP] in CH2Cl2 displays anear-UV Soret band (B) at 383 nm ( = 2.85 × 105 dm3 mol-1 cm-1) and two visible Q(1,0) and Q(0,0) bands at501 ( = 1.45 × 104 dm3 mol-1 cm-1) and 533 ( = 1.36 × 104 dm3 mol-1 cm-1) nm, respectively. Theseabsorption bands of [PtF28TPP] are blue-shifted from those in [PtF20TPP] (390, 504, and 538 nm, respectively) and[PtTPP] (401, 509, and 539 nm, respectively). Excitation of [PtF28TPP] (complex concentration = 1.5 × 10-6 moldm-3) in dichloromethane at the Soret or Q(1,0) or Q(0,0) band gave a phosphorescence with peak maximum at650 nm (lifetime = 5.8 s) and a weak shoulder at 712 nm. Both the emission lifetime and quantum yield vary withsolvent polarity, and plots of versus EK and versus EK (where EK is the empirical solvent polarity parameterbased on the hypsochromic shift of the longest wavelength absorption of the [Mo(CO)4{(C5H4N)HC=NCH2C6H5}]complex with increasing solvent polarity; see: Kamlet, M. J.; Abboud, J. L. M.; Taft, R. W. Prog. Phys. Org. Chem.1981, 13, pp 485-630) show linear correlation, indicating that the emission is sensitive to the local environment/medium. Electrochemical studies on [PtF28TPP] by cyclic voltammetry showed no porphyrin-centered oxidation atpotential 1.5 V versus Ag/AgNO3, demonstrating that [PtF28TPP] is more resistant toward oxidation than [PtF20TPP] (E1/2 = 1.33 V) and [PtTPP] (E1/2 = 0.97 V). The porphyrin-centered reduction of [PtF28TPP] occurs at -0.75and -1.18 V, which is anodically shifted from those at -1.06 and -1.55 V in [PtF20TPP], and -1.51 V in [PtTPP],respectively. The excited-state reduction potential of [PtF28TPP] is estimated to be 1.49 V versus Ag/AgNO3. Over97% of the emission intensity of [PtF28TPP] was retained after irradiation with a high power mercury arc lamp (500W) for 14 h, compared to 90% and 12% for [PtF20TPP] and [PtTPP], respectively; hence, [PtF28TPP] exhibitssuperior photostability. Quenching of the emission of [PtF28TPP] by oxygen, alcohol, catechol, and butylaminereveals that [PtF28TPP] is an oxidatively robust material with medium-sensitive photoluminescence properties.