Phosphorescent Calcium-Based Metal–Organic Framework with Second-Scale Long Afterglow

Abstract

Presented here is a calcium-based metal–organic framework (Ca-MOF) with obvious room temperature phosphorescence. Notably, a long afterglow can be observed by the naked eye and lasts about 4 s, which is mainly attributed to the unique framework structure of the Ca-MOF.

Facile Synthesis of a Long Afterglow Calcium–Organic Framework in Water

“…Ca-MOF-1 was synthesized according to our former report. 28 The plate crystals of Ca-MOF-2 can be easily obtained by soaking block crystals of Ca-MOF-1 in water for one day (see the Supporting Information in detail). The crystal structure of Ca-MOF-2 is the same as that previously reported.…”

“…[Ca(IDC) (H 2 O) 2 ]·H 2 O: for the synthetic method of Ca-MOF-1 ([Ca 3 (IDC) 2 (DMF) 2 (HCOO) 2 ]), we referred to the literature reported previously. 28 CaCl 2 (80 mg, 0.72 mmol) was added to a 3.0 mL DMF solution containing 4,5-imidazoledicarboxylic acid (30 mg, 0.19 mmol) and formic acid (50 μL) in a glass vial. The resulting solution was stirred for 40 min and then heated to 120 °C for 5 days.…”

“… 3 Considering the low cost and toxicity, the development of alkaline-earth metal-based materials is of special significance. 28 , 29 Unfortunately, the research in this field is still rare due to their poor stability.…”

“…Recently, we have reported one RTP Ca-MOF [Ca 3 (IDC) 2 (DMF) 2 (HCOO) 2 ] (Ca-MOF-1) (H 2 IDC = 4,5-imidazoledicarboxylic acid; DMF = N , N -dimethylformamide), which exhibited strong RTP with long phosphorescence lifetime. 28 Its long afterglow lasted as long as ca. 4 s. Interestingly, Ca-MOF-1 can be transformed into another RTP compound Ca-MOF-2 in our subsequent research.…”

Formaldehyde recognition through aminal formation in a luminescent metal–organic framework

“…In addition, the reticular chemistry of MOFs has enabled the synthesis of isoreticular structures with varied pore size and surface chemistry. 4,5 Luminescent MOFs (LMOFs) [6][7][8] are promising materials in the realms of fluorescence probing, 9,10 long afterglow emission, 11 biological imaging 12 and so on. Over the past few decades, linker and cluster functionalization have been frequently used to tune the luminescence of the LMOFs and, more importantly, to enrich the target molecules with a focus on achieving pronounced luminescence changes.…”