Manipulating spatial alignment of donor and acceptor in host-guest MOF for TADF.
Manipulating spatial alignment of donor and acceptor in host-guest MOF for TADF.
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操纵TADF主客体MOF中供体和受体的空间排列
DOI：
10.1093/nsr/nwab222
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发表时间：
2022-08
影响因子：
20.6
通讯作者：
中科院分区：
文献类型：
--
作者：
当富电子三苯（Tpl）供体被限制在以缺电子2,4,6-三（吡啶-4-基）-1,3,5-三嗪（Tpt）受体为配体的笼型多孔金属有机骨架（MOF）宿主（NKU-111）上时，实现了热激活延迟荧光（TADF）。空间上分离的供体和受体分子以面对面的堆叠模式产生强烈的穿越空间电荷转移（CT）相互作用，单线态和三重态激发态之间的能量分裂很小（~ 0.1 eV），从而实现了TADF。随着温度的升高，所得Tpl@NKU-111表现出罕见的增强发射强度。广泛的稳态和时间分辨光谱测量和第一线原理模拟揭示了该化合物在基态和低洼激发态的化学和电子结构。发现了与S1的双通道（T1, T2）系统交叉机制，并解释为从客体供体的简并HOMO - 1/HOMO到最近受体之一的LUMO+1的单向CT。化合物的刚性骨架和有效的透空CT增强了光致发光量子产率（PLQY）。通过优化主机框架的Tpl加载比例，最大PLQY为57.36%。这些结果表明mof在定向构建和优化TADF材料方面具有潜力。提出了一种主客体MOF策略来实现基于空间电荷转移的TADF和可调PLQY，并通过光谱测量和第一性原理模拟进行了验证。
Thermally activated delayed fluorescence (TADF) was achieved when electron-rich triphenylene (Tpl) donors were confined to a cage-based porous metal-organic framework (MOF) host (NKU-111) composed of electron-deficient 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (Tpt) acceptor as the ligand. The spatially separated donor and acceptor molecules in a face-to-face stacking pattern generated strong through-space charge transfer (CT) interactions with a small energy splitting between the singlet and triplet excited states (∼0.1 eV), which enabled TADF. The resulting Tpl@NKU-111 exhibited an uncommon enhanced emission intensity as the temperature increased. Extensive steady-state and time-resolved spectroscopic measurements and first-principles simulations revealed the chemical and electronic structure of this compound in both the ground and low-lying excited states. A double-channel (T1, T2) intersystem crossing mechanism with S1 was found and explained as single-directional CT from the degenerate HOMO−1/HOMO of the guest donor to the LUMO+1 of one of the nearest acceptors. The rigid skeleton of the compound and effective through-space CT enhanced the photoluminescence quantum yield (PLQY). A maximum PLQY of 57.36% was achieved by optimizing the Tpl loading ratio in the host framework. These results indicate the potential of the MOFs for the targeted construction and optimization of TADF materials. A host-guest MOF strategy has been raised to achieve through-space charge transfer based TADF and modulable PLQY, which has been verified by spectroscopic measurements and first-principles simulations.
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影响因子：
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