Delayed fluorescence from a zirconium(iv) photosensitizer with ligand-to-metal charge-transfer excited states

Yu Zhang, Tia S. Lee, Joseph M. Favale, Dylan C. Leary, Jeffrey L. Petersen, Gregory D. Scholes, Felix N. Castellano, Carsten Milsmann

Research output: Contribution to journalArticlepeer-review

138 Scopus citations


Advances in chemical control of the photophysical properties of transition-metal complexes are revolutionizing a wide range of technologies, particularly photocatalysis and light-emitting diodes, but they rely heavily on molecules containing precious metals such as ruthenium and iridium. Although the application of earth-abundant ‘early’ transition metals in photosensitizers is clearly advantageous, a detailed understanding of excited states with ligand-to-metal charge transfer (LMCT) character is paramount to account for their distinct electron configurations. Here we report an air- and moisture-stable, visible light-absorbing Zr(iv) photosensitizer, Zr(MesPDPPh)2, where [MesPDPPh]2− is the doubly deprotonated form of [2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine]. This molecule has an exceptionally long-lived triplet LMCT excited state (τ = 350 μs), featuring highly efficient photoluminescence emission (Ф = 0.45) due to thermally activated delayed fluorescence emanating from the higher-lying singlet configuration with significant LMCT contributions. Zr(MesPDPPh)2 engages in numerous photoredox catalytic processes and triplet energy transfer. Our investigation provides a blueprint for future photosensitizer development featuring early transition metals and excited states with significant LMCT contributions. [Figure not available: see fulltext.]

Original languageEnglish (US)
Pages (from-to)345-352
Number of pages8
JournalNature chemistry
Issue number4
StatePublished - Apr 1 2020

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering


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