Ligand Shell Isomerization Induces Different Fluorescence Origins of Two Au₂₈ Nanoclusters

Abstract

Understanding the origin of the photoluminescence (PL) phenomenon in ligand-protected metal nanoclusters is of paramount importance in both fundamental science and practical applications. In this study, we have studied the origin of fluorescence emission of two thiolate-ligand-protected Au 28 clusters (Au 28 (CHT) 20 and Au 28 (TBBT) 20 ) by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Theoretical calculation results show that the ligand shell isomerization induces different ligand motif-to-metal core charge transfers (LMCT) of Au 28 (TBBT) 20 and Au 28 (CHT) 20 . Moreover, in Au 28 (CHT) 20 , the emission process of S 2 → S 0 can compete favorably with the internal conversion of S 2 → S 1 . Furthermore, the high quantum yield of Au 28 (CHT) 20 is attributed to its high symmetric structure, which leads to less energy dissipation during the structural relaxation process.

Nanocluster Transformation Induced by SbF6– Anions toward Boosting Photochemical Activities

“…By comparison, the N 2 -purged solution of Pt 1 Ag 30 –SbF 6 showed a higher PL QY (85%) than the ambient solution (54%), whereas the O 2 -saturated solution quenched PL to QY of 10% (Figure S20C). In this context, the PL nature of Pt 1 Ag 28 and Pt 1 Ag 30 nanoclusters might be different. − The structural reconstruction from Pt 1 Ag 28 to Pt 1 Ag 30 played a critical role in affecting the intersystem crossing from the S1 to the T1 and, subsequently, giving rise to their different PL nature. − The triplet-state emission from Pt 1 Ag 30 –SbF 6 was verified by observing 1 O 2 production over the photoexcited Pt 1 Ag 30 –SbF 6 , in which the triplet state of Pt 1 Ag 30 –SbF 6 transferred its energy to the normal triplet state 3 O 2 , giving rise to singlet state 1 O 2 . The spectrum of the N 2 -purged Pt 1 Ag 30 –SbF 6 solution was absent of 1 O 2 emission, while the O 2 -saturated Pt 1 Ag 30 –SbF 6 solution exhibited a distinct 1 O 2 emission peak centered at about 1270 nm (Figure S21), demonstrating the notable generation of 1 O 2 and the triplet-state emission of the Pt 1 Ag 30 –SbF 6 nanocluster.…”

Visible to NIR‐II Photoluminescence of Atomically Precise Gold Nanoclusters

“…Last but not least, DFT calculations [10,97,98,205,206] of the PL properties of gold NCs are critically needed, especially with the triplet states taken into consideration. The simulations of electron dynamics in the NCs are generally quite challenging, but future efforts should overcome the challenges and increase the accuracy for direct comparison with the experiment.…”

Controlling the Nature of Photoluminescence of Emissive Metal Nanoclusters

“…Li et al . studied the PL origin of two isomeric Au 28 (SR) 20 nanoclusters via theoretical calculations [22] . Because of the higher symmetric structure of Au 28 ‐1, its higher quantum yield could be attributed to a slight distortion in the geometric structure between the ground and excited states, and hence less energy dissipation during the structural relaxation occurred.…”

“…[21] Li et al studied the PL origin of two isomeric Au 28 (SR) 20 nanoclusters via theoretical calculations. [22] Because of the higher symmetric structure of Au 28 -1, its higher quantum yield could be attributed to a slight distortion in the geometric structure between the ground and excited states, and hence less energy dissipation during the structural relaxation occurred. In addition, as shown in Fig- ure 4C,D, the luminescence of Au 28 -1 originated from a stronger S 2 !S 0 transition while Au 28 -2 had a conventional S 1 !S 0 transition.…”