A terbium metal–organic framework with stable luminescent emission in a wide pH range that acts as a quantitative detection material for nitroaromatics

Abstract

Nitroaromatics are the principal components of explosives and the infamous environmental pollutants in organic synthesis industry. Although high sensitivity towards the detection of nitroaromatics have been demonstrated, selective and quantitative detection are critical for practical applications. Luminescent MOFs constructed by d 10 transition metal ions (Zn/Cd) and π-conjugated ligands for nitro aromatics sensing have been widely reported, but the detection efficiency is insufficient due to the weak and non-characteristic luminescence behaviours. And, the luminescent MOFs constructed by lanthanide ions which possess enhanced characteristic and strong luminescence emission for nitroaromatic detection are rare. Herein, we report a fluorescent MOF with stable emissions, [Tb(L1)2/3(L2)1/2(H2O)2]·2H2O (where H3L1 = 2,4,6-tris(4carboxyphenoxy)-1,3,5-triazine, H2L2= terephthalic acid), whose characteristic emission intensity can keep more than 80% in wide pH range (pH = 4-10). Interestingly, this luminescent MOF can quantitatively detect the nitroaromatics.

Metal-organic framework [H2NMe2]3 [Tb(PDA)3] induces cytotoxic effects and changes DNA methylation-related gene expression in a human fibroblast cell line

“…Yield: 60.9 mg, 72%. IR (ATR, cm- 2017) and the compound had the same molecular structure as that previously reported here (Wang et al 2015) (Supplementary Fig. 1).…”

Two Novel Lanthanide Metal–Organic Frameworks: Selective Luminescent Sensing for Nitrobenzene, Cu2+, and MnO4–

“…The probable causes for luminescence quenching by NB are discussed as follows: (1) The PXRD patterns of 2 in different solvents remained unchanged indicating the collapse of the framework is not the cause of fluorescence quenching (Figure S6); (2) the UV/vis spectra, NB has no absorption band (Figure S7), demonstrating the competing absorption is not the reason; (3) fluorescence intensity of Ln-MOFs largely depend on the energy transfer efficiency between the π conjugated ligand and the Ln 3+ center. Thus, a possible mechanism may be allied to the photoinduced electron transfer (PET) from an electron-rich excited MOF to the electron-deficient NB. − …”

Applications of nanoscale metal–organic frameworks as imaging agents in biology and medicine

“…Lanthanide MOFs (Ln-MOFs) such as Eu-MOFs, Tb-MOFs and Yb-MOFs are therefore excellent luminescent particles, closely connecting lanthanide metals to π-conjugated organic linkers, which act as antennae, and typically exhibiting good photostability and characteristic fluorescence emission. 23,101,102 For example, Abazari et al have reported the synthesis of a luminescent aminefunctionalized Eu-MOF, Eu:TMU-62-NH2 (TMU stands for Tarbiat Modares University) with 9coordinate Eu(III) centres connected by BDC-NH2 into a MOF with formula [Eu2(BDC-NH2)3(DMF)4]n, which was conjugated with folic acid (FA) for targeted delivery of anticancer drug 5-fluorouracil (5-FU) to MCF-7 breast cancer cells with concomitant in vitro fluorescence cell imaging. 103 Microscopy images exhibited higher cellular uptake of the folic acid conjugated structures compared to the unconjugated ones confirming the targeting effect of FA, and also red fluorescence emission arising from Eu:TMU-62-NH2 which can be used for imaging.…”