Selective sensing of Cr^(VI) and Fe^(Ⅲ) ions in aqueous solution by an exceptionally stable Tb^(Ⅲ)-organic framework with an AIE-active ligand

We herein report a new lanthanide metal-organic framework(MOF) that exhibits excellent chemical stability,especially in the aqueous solution over a wide pH range from 1 to 14.In contrast to many reported lanthanide MOFs,this Tb-based MOF emits cyan fluorescence inherited from the integrated AIEactive ligand,rather than Ln3+ ions.More remarkably,its fluorescence signal features a highly selective and sensitive "turn-off" response toward CrO_(4)^(2-),Cr_(2)O_(7)^(2- )and Fe^(3+) ions,highlighted with the low detection limits down to 68.18,69.85 and 138.8 ppm,respectively.Thus,the exceptional structural stability and sensing performance render this material able to be a superior luminescent sensor for heavy metal ions in wastewater.

Crystalline-State Solvent:Metal-Organic Frameworks as a Platform for Intercepting Aggregation-Caused Quenching

The sequestration of organic luminescent molecules(OLMs)within cage-based metal-organic frameworks(MOFs)as a dispersion platform has been developed to impede aggregation-caused quenching(ACQ).The homogenous encapsulation of distinct luminescent guests of different sizes and emissive behaviors in the cage structure of a MOF resulted in high fluorescent quantum yields of 44.8%for DAPI@NKU-110(DAPI=4',6-diamidino-2-phenylindole),65.4%for TPPA@NKU-110(TPPA=tris(4-(pyridin-4-yl)phenyl)amine),31.3%for R6G@NKU-110(R6G=Rhodamine 6G),and 58.3%for PY@NKU-110(PY=Pyronin Y),attributable to the confinement effect caused by the rigid cages of NKU-110.More significantly,a positive correlation of the encapsulated quantity of OLMs with their concentration in the in-situ solvothermal reaction was unveiled by spectral analysis and utilized to facilely fabricate a white-light-emitting crystal material TPPA+R6G@NKU-110.This material features a large crystal size on the millimeter-scale,broadband white emission,ideal CIE coordinates(0.33,0.34),and a high quantum yield(49.1%)when excited at 365 nm.Moreover,such a strategy can be easily generalized to an abundance of other cage-based MOFs and a plentiful volume of OLMs for the future development of colorful,high performance luminescent materials.

A highly stable terbium metal-organic framework for efficient detection of picric acid in water

A highly stable fluorescent terbium MOF(Tb_(4)(paip)_(6)·1.2 H_(2) O,paip = 5-(1 H-pyrazole-4-yl)isophthalate)showing a sharp green emission(545 nm) and a quantum yield of 21.0% was successfully synthesized.This compound is shown to be a recyclable sensor for detecting picric acid in aqueous solution with both high sensitivity and selectivity,attributed to the electron transfer quenching mechanism.

In-situ cation exchange enhances room temperature phosphorescence of a family of metal-organic frameworks

The rational designability and chemical tunability of metal-organic frameworks(MOFs)are enabling tributes to efficaciously enhance their room temperature phosphorescence(RTP)performance.A family of stable anionic MOFs,[Zn_(2)(4,5-ImDC)_(2)]M_(2)(NKU-132,M=(CH_(3))_(2)NH_(2)or(CH_(2)CH_(3))_(2)NH_(2)),featuring significant RTP have been synthesized.By rational cation selection and in-situ replacement from dimethylammonium to diethylammonium,the phosphorescence lifetime is increased from 30.88 to126.3 ms,along with less sensitivity to air.This work provides an anti-quenching and lifetime tuning example for RTP-MOFmaterials via facile host-guest chemistry.