Dissecting the Triplet-State Properties and Intersystem Crossing Mechanism of the Ligand-Protected Au13 Superatom

Kouta Yoshida; Daichi Arima; Masaaki Mitsui

doi:10.1021/acs.jpclett.3c02977

Dissecting the Triplet-State Properties and Intersystem Crossing Mechanism of the Ligand-Protected Au₁₃ Superatom

J Phys Chem Lett. 2023 Dec 14;14(49):10967-10973. doi: 10.1021/acs.jpclett.3c02977. Epub 2023 Dec 1.

Authors

Kouta Yoshida¹, Daichi Arima¹, Masaaki Mitsui¹

Affiliation

¹ Department of Chemistry, College of Science, Rikkyo University, 3-34-1, Nishiikebukuro, Toshima-ku, Tokyo 171-8501, Japan.

PMID: 38038710
DOI: 10.1021/acs.jpclett.3c02977

Abstract

Icosahedral Au₁₃ nanoclusters are among the most typical superatoms and are of great interest as promising building blocks for nanocluster-assembled materials. Herein, the key parameters involved in the intersystem crossing (ISC) process of [Au₁₃(dppe)₅Cl₂]³⁺ (Au₁₃; dppe = 1,2-bis(diphenylphosphino)ethane) were characterized. Quenching experiments using aromatic compounds revealed that the T₁ energy of Au₁₃ is 1.63 eV. An integrative interpretation of our experimental results and the relevant literature uncovered important facts concerning the Au₁₃ superatom: the ISC quantum yield is unity due to the ultrafast ISC (∼10¹² s^-1), the lowest absorption band includes contributions of direct singlet-triplet transitions, and there exists a large S₁-T₁ gap of 0.73 eV. To explain the efficient ISC, the El-Sayed rule was applied to the superatomic orbitals corresponding to the excited-state hole/electron distributions obtained from theoretical calculations. The strong spin-orbit coupling between the S₁ and T₂-T₄ states offers a reasonable explanation for the ultrafast ISC.