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The exploitation of photo-responsive metal–organic frameworks (MOFs) is important in the field of optical switching, advanced detection, and molecular machines. However, it remains challenging due to the heavy dependence on conventional organic photochromic molecules. Herein, a novel photochromic MOF based on benzophenone units, [Zn4(μ2-O)(μ3-O)(cdip)2(DMF)]n (H4cdip = 5,5′-carbonyldiisophthalic acid) (1), has been successfully synthesized. Compound 1 exhibits instant and reversible photochromic behavior under 365 nm UV and X-ray irradiation through the radical formation of benzophenone units. Furthermore, the fluorescence of 1 can be reversibly modulated during the photochromic process. The excellent stability and reproducibility make it suitable for inkless erasable printing paper. [ABSTRACT FROM AUTHOR]

Lanthanide metal–organic frameworks (Ln‐MOFs) are promising for luminescence detection of volatile organic compound (VOC) vapors, but usually suffer from the silent or quenched Ln3+ emission. Herein, we report a new dual‐emissive Eu‐MOF composed of the coordinatively unsaturated Eu9 clusters that afford abundant open metal sites to form a confined "binding pocket" to facilitate the preconcentration and recognition of VOCs. Single‐crystal structural analyses reveal that specific analytes can replace the OH oscillators in the first coordination sphere of Eu3+ and form a unique hydrogen‐bonding second‐sphere adduct tying adjacent Eu9 clusters together to minimize their nonradiative vibrational decay. With the promoted Eu3+ luminescence, the MOF realizes real‐time in situ visual sensing of THF vapor (<1 s) and shows a quantitative ratiometric response to the vapor pressure with a limit of detection down to 17.33 Pa. Also, it represents a top‐performing ratiometric luminescent thermometer. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) as a unique class of porous crystalline materials have received comprehensive attention in the past decades. Among them, luminescent MOFs (LMOFs) have been a well‐known branch on account of their relevance as optical materials in contemporary era. The establishment of host–guest hybrid LMOF materials has triggered a hot search area owing to the extensive range of applications that can be adjusted by soliciting different functional luminescent guests. Current developments in the thought‐provoking application of host–guest LMOFs have stretched into far‐ranging fields, including light regulation, imaging, sensing, data encryption, etc. This review discusses on the hybridization of MOFs with functional luminescent particles (LPs) as guests for the construction of a series of extraordinary host–guest luminescent composite materials (LP@MOFs). The basic aspects, involving the preconcentration of MOF hosts and luminous guests as well as the comprehensive synthetic strategies of LP@MOFs are introduced. Furthermore, the applications of luminescent LP@MOF materials are highlighted, with a particular emphasis on the present and continuing challenges and the demand trends of such materials that need to be explored. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) have garnered enormous interest due to their remarkable catalysis activity. However, the exploitation of universal synthesis strategy and regulation of coordination environment of SACs remain a great challenge. Herein, a versatile synthetic strategy is demonstrated to generate a series of transition metal SACs (M SAs/NC, M = Co, Cu, Mn; NC represents the nitrogen‐doped carbon) through defect engineering of metal‐organic frameworks (MOFs). The interatomic distance between metal sites can be increased by deliberately introducing structural defects within the MOF framework, which inhibits metal aggregation and consequently results in an approximately 70% increase in single metal atom yield. Additionally, the coordination structures of metal sites can also be facilely tuned. The optimized Co SAs/NC‐800 exhibits superior activity and excellent reusability for the selective hydrogenation of nitroarenes, surpassing several state‐of‐art non‐noble‐metal catalysts. This study provides a new avenue for the universal fabrication of transition metal SACs. [ABSTRACT FROM AUTHOR]

Lanthanide metal-organic frameworks (Ln-MOFs) are promising for luminescence detection of volatile organic compound (VOC) vapors, but usually suffer from the silent or quenched Ln 3+ emission. Herein, we report a new dual-emissive Eu-MOF composed of the coordinatively unsaturated Eu 9 clusters that afford abundant open metal sites to form a confined "binding pocket" to facilitate the preconcentration and recognition of VOCs. Single-crystal structural analyses reveal that specific analytes can replace the OH oscillators in the first coordination sphere of Eu 3+ and form a unique hydrogen-bonding second-sphere adduct tying adjacent Eu 9 clusters together to minimize their nonradiative vibrational decay. With the promoted Eu 3+ luminescence, the MOF realizes real-time in situ visual sensing of THF vapor (<1 s) and shows a quantitative ratiometric response to the vapor pressure with a limit of detection down to 17.33 Pa. Also, it represents a top-performing ratiometric luminescent thermometer., (© 2022 Wiley-VCH GmbH.)