Houting Liu

Fabrication of porous metal–organic frameworks via a mixed-ligand strategy for highly selective and efficient dye adsorption in aqueous solution

In our efforts toward the rational design and systematic synthesis of porous 3D MOFs, three 3D frameworks of Zn-MOFs ([Zn(BDC)(TIB)]·3H2O (Zn-MOF-1) (TIB = 1,3,5-tri(1H-imidazol-1-ly) benzene and H2BDC = 1,4-dicarboxybenzene), [Zn(BDA)(TIB)2/3]n (Zn-MOF-2) (H2BDA = 4,4′-biphenyl-dicarboxylic acid) and [Zn3(BDC)2(BDA)(TIB)2]n (Zn-MOF-3)) were successfully synthesized, based on different multicarboxylate ligands through solvothermal reactions. The resulting MOFs show similar 3D structures with different pore sizes which lead to distinct selective adsorption for organic dyes. Remarkably, Zn-MOF-1 exhibits an excellent capacity to adsorb CR (congo red) with high selectivity, and it maintains an almost identical adsorption performance after being recycled several times.

A luminescent europium MOF containing Lewis basic pyridyl site for highly selective sensing of o-, m- and p-nitrophenol

A new luminescent two-dimensional europium metal–organic framework [Eu6(L)3(HL)2(H2O)10]·10H2O·x(solvent) (1) has been successfully prepared by the solvothermal reaction of Eu(NO3)3·6H2O and the multidentate π-conjugated ligand H4L (H4L = (5,5′-(pyridine-2,5-diyl)-isophthalic acid)) which has a Lewis basic pyridyl site. The solid sample of 1 emits high bright red light which can be readily observed by the naked eyes when excited at 358 nm at ambient temperature. Interestingly, the luminescence of fine grinding 1 particles dispersed in ethanol can be sensitively and selectively quenched by adding trace amounts of o-, m- and p-nitrophenol (NP), which reveals that 1 can be used as a luminescence sensor for the detection of o-, m- and p-NP.

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

Nitroaromatics are the principal components of explosives and infamous environmental pollutants in the 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 d10 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, 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(4-carboxyphenoxy)-1,3,5-triazine, H2L2 = terephthalic acid), whose characteristic emission intensity can maintain more than 80% in a wide pH range (pH = 4–10). Interestingly, this luminescent MOF can quantitatively detect nitroaromatics.

Metallo-supramolecular grid-type architectures for highly and selectively efficient adsorption of dyes in water

There has been extensive interest in the construction of grid-type supramolecular complexes because of their important roles in material science. However, only few of these compounds have been explored for selective adsorption of dyes. Two novel grid-type architectures composed of mixed valence copper ions and polynitrogen heterocyclic ligands have been successfully synthesized. Interestingly, one of the grid-type architectures with modest grid size could efficiently and selectively adsorb dye molecules.