Near-infrared (NIR) long persistent
luminescent (LPL)
materials
have attracted the interest of many researchers as they have potential
applications in many aspects. However, majority of studies on Cr3+ ion-doped LPL materials have focused on Cr3+ in
an octahedral site, and the luminescence is limited to the short-wavelength
NIR-I region (700–900 nm), which is detrimental to fully explore
Cr3+ ion-doped LPL materials with potential applications.
In this work, a novel ultra-broadband NIR LPL material, Na2CaGe6O14 (NCGO):x%Cr3+, was successfully
designed and synthesized, covering the luminescence range of 600–1200
nm and having the best afterglow duration of more than 10 h. Combining
the luminescence lifetime with the low-temperature spectrum, it was
concluded that the luminescence of NCGO:Cr3+ consists of
the co-emission of Cr3+ in octahedra and tetrahedra. And
it was confirmed by electron paramagnetic resonance (EPR) spectrum
and X-ray absorption near-edge spectrum (XANES). The application prospects
of NCGO:x%Cr3+ in many aspects were investigated in detail.
This work could not only give a reference for researchers to study
Cr3+ luminescence in multiple coordination but also provide
a new strategy for obtaining new ultra-broadband NIR LPL materials.
Following the principle of a topology guide, a zirconium MOF (PCN-207) based on the H 4 TPTA ligand (tetramethyl(4,4′,4″,4‴-(pyrazine-2,3,5,6-tetrayl))tetrabenzoic acid) with C 2 symmetry and an 8-connected Zr 6 (μ 3-OH) 8 (OH) 8 ] 8+ cluster with D 4h symmetry has been synthesized. PCN-206 can also be obtained by modulating the benzoic acid usage to change the flexibility of the H 4 TPTA ligand. The unique positions of 8-connected Zr 6 clusters in the flu and scu networks and the flexibility of the tetratopic primary linker enable the precise insertion of fumarate (FA), 1,4-benzenedicarboxylic acid (H 2 BDC), and even 2,6-naphthalenedicarboxylic acid (H 2 NDC) in a one-pot reaction. Auxiliary linkers are used to generate new MOF structures or topologies or to split the pore spaces, which may significantly change the porosity and chemical and physical properties of scaffold MOFs. The results provide a successful strategy for the rational design of multicomponent Zr-MOFs. Because of differences in composition and configuration between structures, PCN-207 shows the highest separation capability of light hydrocarbons; moreover, PCN-206 exhibits the highest adsorption capacity of 2,4-D and DCF among MOFs at present.
As a reusable material, Persistent luminescence (PersL) materials has a wide range of applications in emergency response, information encryption and other fields. However, there is still a lack of commercial...
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