Heterometallic MOFs constructed from thiophene and furandicarboxylate ligands for heavy metal luminescence sensing.

Rational design of a series of new heterometallic MOFs was carried out by the judicious choice of the corresponding synthesis conditions and ligand geometry. Three heterometallic MOFs (H2NMe2)[LiZn(dmf)(tdc)2]·DMF·H2O (1), [{LiZn}2Li2Zn2(dmf)6(tdc)6]·6DMF·H2O (2) and [Li2Zn2(dmf)2(fdc)3]·2DMF·2H2O (3) were obtained on the basis of the pre-synthesized pivalate complex [Li2Zn2(py)2(piv)6]. The angle between carboxylic groups greatly affects the possibility of retaining the initial tetranuclear node in the structure of the obtained MOFs. Compound 3 demonstrates permanent porosity with a calculated BET surface area value of 287 m2 g-1. Compounds 2 and 3 are capable of heavy metal sorption from their nitrate solution, and a significant flare-up of the luminescence of the obtained inclusion compounds is observed, where the quantum yield of luminescence increases by an order of magnitude in the case of cadmium inclusion.