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Metal–organic frameworks (MOFs) with long persistent luminescence (LPL) have attracted extensive research attention due to their potential applications in information encryption, anticounterfeiting technology, and security logic. The strategic combinations of organic phosphor linkers and metal ions lead to tremendous frameworks, which could unveil many undiscovered properties of organics. Here, the synthesis and characterization of a three-dimensional MOF (Cd-MOF) is reported, which demonstrates enhanced blue photoluminescence and a phosphorescent lifetime of 124 ms as compared to the pristine linker (H2L) under ambient conditions due to the scaffolding and heavy-atom effects of metal chains in the framework. Notably, the Cd-MOF exhibits intriguing excitation-, time-, and temperature-dependent LPL, with a duration of 3 s at room temperature and the ability to shift from blue to green to yellow at lower temperatures. Optical characterizations and theoretical calculations reveal that H2L molecules are responsible for the emissions in the Cd-MOF, while LPL properties of molecular phosphors can be significantly enhanced and regulated through coordination interactions and heavy-atom effect of the metal chains. This work highlights the potential of such materials as promising candidates for multiple anticounterfeiting, displaying, and encryption applications.

AbstractThe anaerobic sludge granulation was studied in two laboratory-scale continuous-flow stirred tank reactors (CSTRs), which treating synthetic glucose wastewaters under a mesophilic constant temperature of 35 ± 1°C. Different stirring strategies were employed in the two CSTRs. Magnetic stirring at a rotation speed of 140 rpm was used in CSTR1 and axial continuous agitation at a speed of 90 rpm in CSTR2. It was observed that highly activated granular sludge formed in CSTR2, but flocculent sludge still remained in CSTR1 after about 45 days’ cultivation. Liquid circulation analysis of the two stirring modes displayed that the overall circulation in CSTR2 was more uniform. Furthermore, calculation results proved that the hydraulic shear force produced in CSTR2 was more suitable for granules formation than it in CSTR1, and granules did form in the CSTR2. Therefore, it could be concluded that in the laboratory-scale CSTR, stirring strategy played a key role in sludge granulation. On the other hand, scanning electron microscope images of granular sludge displayed that filamentous bacterial dominated in the outer layer and bacilli surrounded by lots of extracellular polymeric substances in the inner layer. Both of these are beneficial to promote the granules formation and maintenance.

A homochiral MOF was used as a new chiral stationary phase and had an excellent recognition ability for various racemates in HPLC. The results indicated that the optical selectivity of the natural chiral MOF column is practical in HPLC, which promotes the application of chiral MOFs for enantioseparation.