Constructions of new luminescent 3D porous MOFs with high stability, unique selectivity and low detection limits for various ions in aqueous solution.

Three new luminescent metal-organic frameworks (MOFs), {[Zn(L)(H 2 O)]·2H 2 O} n (1), {[Pb(L)]·0.5DMA} n (2), and {[Cd 2 (L) 2 (H 2 O) 2 ·2H 2 O} n (3) were synthesized by an asymmetric N-containing 2-pyrimidin-5-yl-terephthalic acid (H 2 L) ligand with Zn2+, Pb2+, and Cd2+ ions, respectively. In these complexes, L2− ligand exhibits the multiple coordination modes with metal ions to form different new structures; especially there exist the different secondary building units (SBUs) in 2 and 3. The solid-state luminescent properties of complexes 1-3 were studied at room temperature and the mechanism was analyzed carefully. In particular, complex 2 has good stability in aqueous solution and exhibits the specific selectivity and sensitivity to probe Fe3+, MnO 4 −, CrO 4 2− and Cr 2 O 7 2− simultaneously, and the detection limits of Fe3+ and Cr 2 O 7 2− ions are 5.6 ​× ​10−5 and 10−6, respectively. These are lower than those of other reported sensors. Finally, its quenching mechanism has also been studied in detail. Three new luminescent MOFs were synthesized successfully, where the L2− ligand exhibits the multiple coordination modes with metal ions to form new different structures; especially there exist the different secondary building units (SBUs) in 2 and 3. Complex 2 has good stability in aqueous solution and exhibits the specific selectivity and sensitivity to Fe3+, MnO 4 −, CrO 4 2− and Cr 2 O 7 2− ions. Image 1 • Three new luminescent MOFs with Zn2+, Pb2+, and Cd2+ ​ions were prepared successfully by a new N-containing ligand. • The L2- ligand may exhibit the multiple coordination modes with various metal ions to form different new structures. • The solid-state luminescent properties of ​ 1-3 ​were studied at room temperature and the mechanism was analyzed. • Complex ​ 2 ​can selectively probe Fe3+, MnO 4 −, CrO 4 2− ​and Cr 2 O 7 2− ​simultaneously in the aqueous solution.The detection limit can reach 10-4 ​to 10-6, which is lower for detection with those of the reported sensors. [ABSTRACT FROM AUTHOR]