Host–guest systems based on donor–acceptor interactions have attracted considerable attention as a new platform for the preparation of luminescent metal–organic frameworks (MOFs). However, reasonable design and modulation of donor–acceptor interactions with charge transfer based fluorescence remains a challenge owing to the elaborate self-assembly process of acceptor and donor components. Taking into account the design principles of the host–guest system, a well-defined MOF with an electron-deficient nature should be an ideal host for the building of charge transfer based fluorescent materials. Herein, we have successfully fabricated a suite of host–guest materials (MOFs 2–8) exhibiting charge transfer based fluorescence by virtue of the interactions between electron-rich naphthalene derivatives and an electron-deficient naphthalene diimide-based MOF (MOF 1) as the donor and acceptor, respectively. Profiting from the clear naphthalene derivatives to electron-deficient MOF framework charge transfer interactions, these host–guest materials exhibit color-tunable emissions over a wide range by rational selection of naphthalene derivative molecules. Furthermore, electronic structure calculations reveal that the multicolor emissions of the newly synthesized MOFs depend on the HOMO energy level/ionization potential of naphthalene derivatives. This work provides a promising strategy for the assembly of various novel charge-transfer fluorescent materials as potential luminophores.

中文翻译：

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富电子客体对萘二亚胺基金属有机骨架发光的调制效应

基于供体 - 受体相互作用的主客体系统作为制备发光金属有机框架（MOF）的新平台引起了相当大的关注。然而，由于受体和供体组分的复杂自组装过程，合理设计和调制供体-受体相互作用与基于电荷转移的荧光仍然是一个挑战。考虑到主客体系统的设计原则，定义明确的具有缺电子性质的 MOF 应该是构建基于电荷转移的荧光材料的理想主体。在这里，我们成功地制造了一套主客体材料（MOFs 2-8) 通过富电子萘衍生物和缺电子萘二亚胺基 MOF (MOF 1 ) 分别作为供体和受体之间的相互作用表现出基于电荷转移的荧光。从清晰的萘衍生物到缺电子 MOF 框架电荷转移相互作用，这些主客体材料通过合理选择萘衍生物分子在大范围内表现出颜色可调的发射。此外，电子结构计算表明，新合成的 MOF 的多色发射取决于萘衍生物的 HOMO 能级/电离势。这项工作为组装各种新型电荷转移荧光材料作为潜在的发光体提供了一种有前景的策略。