Luminescent silver clusters that are confined inside porous zeolites have attracted great research interest due to the combined advantages of high quantum yield, tunable emission, excellent chemical stability, and desirable adoption ability of this micronano-composite. In this research, a series of Ag-exchanged R-LTA/Ag (R = Li, Na, K) zeolites were synthesized, in which the silver clusters showed blue-shifted excitation in the UV region, red-shifted emission in the visible region, and decreased emission intensity when taking Li⁺, Na⁺, and K⁺ as the extra-framework cations, respectively. The [Ag₄(H₂O)_xR₄-sod]^6– (x = 2, 4; R = Li, Na, K) structures were constructed, and the TD-DFT method was further carried out to study the influence of extra-framework cations on the luminescence performance of [Ag₄]²⁺ clusters, in which the substitution of Al for Si and the reasonable hydrate levels were both taken into consideration. It is estimated that the S₁ and S₃ levels for the [Ag₄(H₂O)₄Li₄-sod]^6– cluster, the S₄ level for the [Ag₄(H₂O)₄Na₄-sod]^6– cluster, and the S₅ level for the [Ag₄(H₂O)₂K₄-sod]^6– cluster can be effectively populated through direct excitation, and the S₁ → S₀ transition is assumed to be responsible for the radiative emission in the visible region for the [Ag₄]²⁺ pseudo-tetrahedrons. This calculated energy level diagram and simulated absorption spectra of [Ag₄(H₂O)_xR₄-sod]^6– (x = 2, 4; R = Li, Na, K) clusters explained the modified luminescence property of silver clusters in R-LTA/Ag (R = Li, Na, K) zeolites studied in this research and reported literature.

中文翻译：

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通过调整框架外阳离子对 LTA 分子筛中银团簇发光性能的操纵和理论建模


由于这种微纳米复合材料具有高量子产率、可调发射、优异的化学稳定性和理想的采用能力的综合优势，局限在多孔沸石内部的发光银团簇引起了极大的研究兴趣。在这项研究中，合成了一系列 Ag 交换的 R-LTA/Ag （R = Li， Na， K） 分子筛，其中银簇分别在紫外区域表现出蓝移激发，在可见光区域表现出红移发射，当以 Li⁺、Na⁺ 和 K⁺ 作为框架外阳离子时，发射强度降低。[Ag₄（H₂O）_xR_4-sod]^6– （x = 2， 4;构建了 R = Li、Na、K） 结构，并进一步开展了 TD-DFT 方法，研究了框架外阳离子对 [Ag₄]²⁺ 团簇发光性能的影响，其中考虑了 Al 对 Si 的取代和合理的水合物水平。据估计，[Ag₄（H₂O）₄Li 4-sod]^6– 簇的 S₁ 和 S₃ 能级，[Ag₄（H₂O）₄Na_4-sod]^6– 簇的 S₄ 能级，以及 [Ag₄（H₂O）₂K_4-sod]^6– 簇的 S₅ 能级可以通过直接填充激发，假设 S₁ → S₀ 跃迁是 [Ag₄]²⁺ 伪四面体在可见光区域的辐射发射的原因。 该计算出能级图和模拟吸收光谱 [Ag₄（H₂O）_xR_4-sod]^6– （x = 2， 4;R = Li、Na、K） 簇解释了本研究和报道文献中研究的 R-LTA/Ag （R = Li， Na， K） 沸石中银簇的改性发光特性。