fig2

Figure 2. (A) Schematics of the framework structure of zeolite X. Near the center of each line segment is an oxygen atom. The nonequivalent oxygen atoms are indicated by the numbers 1-4. The common extraframework cation positions are labeled with Roman numerals. One of the four entrances to the supercage is highlighted in red. (B) The [Na₄Cs₆PbBr₄]⁸⁺ quantum dot (QD) in a supercage of zeolite X. (C) Stereoview of the [Na₄Cs₆PbBr₄]⁸⁺ QD. (D) Stereoview of the [Na₄Cs₆PbBr₄]⁸⁺ QD in a Pb, Br, H, Cs, Na-X supercage. This structure may be viewed as a series of concentric spheres of alternating charge (48 O^2- ions of the zeolite framework, 10 Cs⁺ and Na⁺ ions, and 4 Br^- ions) with a Pb²⁺ ion at its center. The two water molecules (at O5 that bond to each Cs⁺ ion at Cs31 are not shown. Reprinted with permission^[54] © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.