Pd-Porphyrin Oligomers Sensitized for Green-to-Blue Photon Upconversion: The More the Better?

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• 作者：Dr. Zhiqing Xun ; Dr. Yi Zeng ; Dr. Jinping Chen ; Dr. Tianjun Yu ; Dr. Xiaohui Zhang ; Prof. Dr. Guoqiang Yang and Prof. Dr. Yi Li
• 刊名：Chemistry - A European Journal
• 出版年：2016
• 出版时间：June 13, 2016
• 年：2016
• 卷：22
• 期：25
• 页码：8654-8662
• 全文大小：1051K
• ISSN：1521-3765

文摘

A series of directly meso-meso-linked Pd–porphyrin oligomers (PdDTP-M, PdDTP-D, and PdDTP-T) have been prepared. The absorption region and the light-harvesting ability of the Pd–porphyrin oligomers are broadened and enhanced by increasing the number of Pd–porphyrin units. Triplet–triplet annihilation upconversion (TTA-UC) systems were constructed by utilizing the Pd–porphyrin oligomers as the sensitizer and 9,10-diphenylanthracene (DPA) as the acceptor in deaerated toluene and green-to-blue photon upconversion was observed upon excitation with a 532 nm laser. The triplet–triplet annihilation upconversion quantum efficiencies were found to be 6.2 %, 10.5 %, and 1.6 % for the [PdDTP-M]/DPA, [PdDTP-D]/DPA, and [PdDTP-T]/DPA systems, respectively, under an excitation power density of 500 mW cm⁻². The photophysical processes of the TTA-UC systems have been investigated in detail. The higher triplet–triplet annihilation upconversion quantum efficiency observed in the [PdDTP-D]/DPA system can be rationalized by the enhanced light-harvesting ability of PdDTP-D at 532 nm. Under the same experimental conditions, the [PdDTP-D]/DPA system produces more ³DPA* than the other two TTA-UC systems, benefiting the triplet–triplet annihilation process. This work provides a useful way to develop efficient TTA-UC systems with broad spectral response by using Pd–porphyrin oligomers as sensitizers.