Self-Assembly versus Stepwise Synthesis: Heterometal-Organic Frameworks Based on Metalloligands with Tunable Luminescence Properties

A new family of heterometal-organic frameworks has been prepared by two synthesis strategies, in which IFMC-26 and IFMC-27 are constructed by self-assembly and IFMC-28 is obtained by stepwise synthesis based on the metalloligand (IFMC=Institute of Functional Material Chemistry). IFMC-26 is a (3,6)-connected net and IFMC-27 is a (4,8)-connected 3D framework. The metalloligands {Ni(H4L)}(NO3)(2) are connected by binuclear lanthanide clusters giving rise to a 2D sheet structure in IFMC-28. Notably, IFMC-26-EuxTby and IFMC-28-EuxTby have been obtained by changing the molar ratios of raw materials. Owing to the porosity of IFMC-26, Tb3+@IFMC-26-Eu and Eu3+@IFMC-26-Tb are obtained by postencapsulating Tb-III and Eu-III ions into the pores, respectively. Tunable luminescence in metal-organic frameworks is achieved by the two kinds of doping methods. In particular, the quantum yields of heterometal-organic frameworks are apparently enhanced by postencapsulation of Ln(III) ions.