Through an ion exchange method, the composite 1⊃HPTS was prepared via the introduction of HPTS (8-hydroxy-1,3,6-pyrenetrisulfonicacid trisodium salt) into the channels of the compound [Zn(TIPA)(NO₃ ⁻)₂(H₂O)]·5H₂O (1). 1⊃HPTS exhibits durable dual-emission performance of both blue and yellow-green emission, and could act as a two-signal platform in aqueous solution. 1⊃HPTS exhibits ultrahigh sensitive response to a wide range of nitro-compounds, including nitroaromatics, aliphatic nitro-explosives and nitro-containing antibiotics. Particularly, 1⊃HPTS displays ratiometric fluorescence response against RDX. To the best of our knowledge, this is the first MOF-based probe with such an effect for the identification of RDX among luminescent materials. Moreover, the film based on the 1⊃HPTS sample shows high sensitivity towards 4-TNP vapor with good reusability. We also demonstrated that the detection of nitro-compounds using 1⊃HPTS predominantly involved photo-induced electron transfer and fluorescence resonance energy transfer.

Compound 1 could be used as a single crystal container to capture Cr(vi)-oxyanions via ion exchange with high capacity and selectivity. It is the first report that demonstrates that CrO₄²⁻ ions could be traced and confirmed through a single-crystal to single-crystal (SC–SC) pattern.

A water-stable porous anionic metal–organic framework (MOF), [(CH ₃ ) ₂ NH ₂ ][In(TNB) _4/3 ]·(2DMF)(3H ₂ O) ( 1 , H ₃ TNB = 4,4′,4′′-nitrilotribenzoicacid), was synthesized.

Delayed luminescence (DF), including phosphorescence and thermally activated delayed fluorescence (TADF), and circularly polarized luminescence (CPL) exhibit common and broad application prospects in optoelectronic displays, biological imaging, and encryption. Thus, the combination of delayed luminescence and circularly polarized luminescence is attracting increasing attention. The encapsulation of guest emitters in various host matrices to form host–guest systems has been demonstrated to be an appealing strategy to further enhance and/or modulate their delayed luminescence and circularly polarized luminescence. Compared with conventional liquid crystals, polymers, and supramolecular matrices, porous crystalline frameworks (PCFs) including metal–organic frameworks (MOFs), covalent-organic frameworks (COFs), zeolites and hydrogen-bonded organic frameworks (HOFs) can not only overcome shortcomings such as flexibility and disorder but also achieve the ordered encapsulation of guests and long-term stability of chiral structures, providing new promising host platforms for the development of DF and CPL. In this review, we provide a comprehensive and critical summary of the recent progress in host–guest photochemistry via the encapsulation engineering of guest emitters in PCFs, particularly focusing on delayed luminescence and circularly polarized luminescence. Initially, the general principle of phosphorescence, TADF and CPL, the combination of DF and CPL, and energy transfer processes between host and guests are introduced. Subsequently, we comprehensively discuss the critical factors affecting the encapsulation engineering of guest emitters in PCFs, such as pore structures, the confinement effect, charge and energy transfer between the host and guest, conformational dynamics, and aggregation model of guest emitters. Thereafter, we summarize the effective methods for the preparation of host–guest systems, especially single-crystal-to-single-crystal (SC–SC) transformation and epitaxial growth, which are distinct from conventional methods based on amorphous materials. Then, the recent advancements in host–guest systems based on PCFs for delayed luminescence and circularly polarized luminescence are highlighted. Finally, we present our personal insights into the challenges and future opportunities in this promising field.