New synthesis of zinc tetrakis(arylethynyl)porphyrins and substituent effects on their redox chemistry.
Sonogashira coupling of zinc 5,10,15,20-tetraethynylporphyrin with various phenyl iodides under mild conditions afforded good yields of the corresponding zinc porphyrins. This method is applicable to a variety of aryl iodides including meso-substituted iodoporphyrin to form a conjugated star-shaped multiporphyrin. The UV-Vis spectra show that peak broadening, red shifts, and changes in the oscillator strength of absorptions increase with the extension of pi-conjugation. In the electrochemical measurements, the first oxidation of porphyrins 4-9 occurs at potentials in the range +0.89 to +1.08 V, which are comparable to that of ZnTPP (TPP = tetraphenylporphyrin). The first reduction was observed at potentials from -0.73 to -0.89 V, which is anodically shifted by 390-550 mV as compared to that of ZnTPP, and the second reduction occurs at potentials in the range -1.12 to -1.33 V. The para-substituted tetrakis(phenylethynyl)porphyrins show substituent effects on their redox chemistry and exhibit only slight substituent effects in their emission and absorption maxima.
Kuo
Ming-Cheng
MC
Department of Chemistry and Center of Nanoscience and Nanotechnology, National Chung Hsing University, Taichung 402, Taiwan.
Li
Long-An
LA
Yen
Wei-Nan
WN
Lo
Shang-Shih
SS
Lee
Cheng-Wei
CW
Yeh
Chen-Yu
CY
D007454:Iodides / Q000737:chemistry*; D008665:Metalloporphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
D007454:Iodides; D008665:Metalloporphyrins; D011166:Porphyrins; C409084:tetraphenylporphyrin; C474512:zinc-tetrakis(p-sulfonatophenyl)porphyrin