Research ArticleChemistry

Ultrastable atomically precise chiral silver clusters with more than 95% quantum efficiency

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Science Advances  07 Feb 2020:
Vol. 6, no. 6, eaay0107
DOI: 10.1126/sciadv.aay0107
  • Fig. 1 Silver cluster and ligand structures, images of single crystals, and PXRD patterns.

    (A) Ball-and-stick representation of the enantiomers of Ag6L6/D6 and Ag6PL6/PD6. Inset: Schematic of the Ag6 octahedron core in these enantiomers. (B) Structures of L/D and PL/PD. (C) The octahedral Ag6 framework in Ag6L6/D6. Color codes: Ag, green; C, gray; S, yellow; N, blue; H atoms are omitted for clarity. (D) Images of single crystals of Ag6L6 under ambient light (top) and UV light (bottom) at different temperatures. See the images of Ag6PL6 single crystals in fig. S3. Photo credit: Zhen Han, Zhengzhou University. (E) Temperature-dependent PXRD patterns of the as-prepared Ag6L6 powder sample and one sample after exposure to UV light for 60 min.

  • Fig. 2 Photoluminescence and WLED assembly.

    (A) Normalized excitation and emission spectra of Ag6L6 and Ag6PL6 in the solid state at RT. (B) Solid-state emission spectra of Ag6L6 at different excitation wavelengths at RT. (C) Comparison of emission spectra between Ag6L6 and a commercial yellow phosphor, cerium-doped yttrium aluminum garnet (YAG: Ce3+), which are nearly identical at RT. The CIE coordinates of Ag6L6 (0.41, 0.55) overlapped those of YAG: Ce3+ (0.41, 0.56). (D) Photographs of WLED assembly: 1, blue LED is turned off (emission range, 450 to 480 nm; OSRAM LED Lighting Company); 2, the same blue LED coated with Ag6L6 powders is turned off; 3, LED coated with Ag6L6 powders emits white light when it is turned on. The green solid line is the monitored emission spectrum. Photo credit: Zhen Han, Zhengzhou University.

  • Fig. 3 Temperature-dependent emission spectra of Ag6L6 and the proposed PL process.

    (A) Normalized temperature-dependent solid-state emission in the range of 50 to 400 K upon excitation at 370 nm. (B) Temperature-dependent solid-state emission intensity in the range of 50 to 400 K. (C and D) Temperature dependence of the excited-state lifetimes in the range of 50 to 300 K. (E) Plot of emission decay lifetime against temperature (50 to 300 K); the red line represents the fit according to the TADF equation (eq. S1 in section S1). (F) Energy diagram of Ag6L6 indicating TADF and phosphorescence (Ph) emission processes. See the main text for details of the processes.

  • Fig. 4 DFT, optical absorption, CD, and CPL.

    (A) Selected frontier molecular orbital representations for Ag6L6 in optimized structures of S0. (B) Experimental optical absorption spectrum (red) of Ag6L6 in CH2Cl2 (10−5 M) compared to the calculated spectrum (black). Gray bars show the individual transitions (delta function–like peaks showing the relative oscillator strengths). (C) Schematic photoinduced transitions in Ag6L6. The core consists of octahedral Ag6 and coordinated N and S atoms, and the shell layer includes the outer noncoordinated atoms of ligand L. (D) CD spectra of clusters Ag6L6/D6 and Ag6PL6/PD6, together with ligands L/D and PL/PD in CH2Cl2 in the wavelength range of 200 to 450 nm. (E) CPL spectra (top) and the corresponding emission spectra (bottom) of Ag6L6 and Ag6D6 in CH2Cl2 (10−5 M). The CPL spectra of Ag6PL6/PD6 in solution are presented in fig. S8.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/6/eaay0107/DC1

    Section S1. Instrumentation and Photophysical Measurements

    Fig. S1. Synthesis and 1H NMR spectra of ligands.

    Fig. S2. Coordination configurations and ESI-MS.

    Fig. S3. TG analyses, PXRD patterns, and images of single crystals of Ag6PL6.

    Fig. S4. UV-vis diffuse reflectance, luminescence, and temperature-dependent solid-state emission lifetimes.

    Fig. S5. PL spectra and decay lifetimes of silver clusters in diluted solution.

    Fig. S6. Photographs of solid-state samples and the fabricated film, and temperature-dependent emission and lifetimes of solid-state Ag6PL6.

    Fig. S7. DFT and TDDFT calculation of Ag6PL6.

    Fig. S8. CD and CPL spectra.

    Table S1. Crystal data and structure refinements.

    Table S2. Bond lengths.

    Dataset S1. Ag6D6-150 K

    Dataset S2. Ag6L6-150 K

    Dataset S3. Ag6PD6-150 K

    Dataset S4. Ag6PL6-150 K

    Dataset S5. Ag6L6-100-370 K

    Dataset S6. Ag6PL6-100-370 K

  • Supplementary Materials

    The PDFset includes:

    • Section S1. Instrumentation and Photophysical Measurements
    • Fig. S1. Synthesis and 1H NMR spectra of ligands.
    • Fig. S2. Coordination configurations and ESI-MS.
    • Fig. S3. TG analyses, PXRD patterns, and images of single crystals of Ag6PL6.
    • Fig. S4. UV-vis diffuse reflectance, luminescence, and temperature-dependent solid-state emission lifetimes.
    • Fig. S5. PL spectra and decay lifetimes of silver clusters in diluted solution.
    • Fig. S6. Photographs of solid-state samples and the fabricated film, and temperature-dependent emission and lifetimes of solid-state Ag6PL6.
    • Fig. S7. DFT and TDDFT calculation of Ag6PL6.
    • Fig. S8. CD and CPL spectra.
    • Table S1. Crystal data and structure refinements.
    • Table S2. Bond lengths.

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    Other Supplementary Material for this manuscript includes the following:

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