Triplet Distribution in a Symmetrical Zinc(II) Porphyrin–BODIPY Pentameric Array

A symmetrical molecular array has been synthesized comprising a central zinc­(II) 5,10,15,20-tetraphenylporphyrin with identical boron dipyrromethene (BODIPY) units appended at each of the meso sites. Excitation of any subunit causes a cascade of electronic energy-transfer steps, ultimately leading...

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Bibliographic Details
Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2020-12, Vol.124 (51), p.10736-10747
Main Authors: Bozdemir, Özgür Altan, Gultekin, Demet Demirci, Harriman, Anthony
Format: Article
Language:English
Subjects:
A: Kinetics, Dynamics, Photochemistry, and Excited States
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Summary:A symmetrical molecular array has been synthesized comprising a central zinc­(II) 5,10,15,20-tetraphenylporphyrin with identical boron dipyrromethene (BODIPY) units appended at each of the meso sites. Excitation of any subunit causes a cascade of electronic energy-transfer steps, ultimately leading to the BODIPY triplet-excited state in high yield. Coincidentally, the triplet energy levels of the zinc­(II) porphyrin and BODIPY appendage are closely balanced such that an equilibrium is established at both 77 K and room temperature. This fast equilibration allows global distribution of the triplet exciton around the array, leading to a significantly increased capture volume for bimolecular quenching and a substantial increase in the rate constant for bimolecular triplet–triplet annihilation. The corresponding free-base porphyrin analogue does not favor triplet exciton decentralization because of the large disparity in the electronic energy levels.
ISSN:1089-5639
1520-5215
DOI:10.1021/acs.jpca.0c09243