Synthesis, fluorescence properties and structural characterization of two heteronuclear Zn(II)-Pr(III) clusters with a chain-shaped ether Schiff base ligand

Abstract

Two new Zn(II)-Pr(III) heteronuclear clusters were synthesized by interfacial diffusion, [ZnPr(L)(NO₃)₂(OAc)(CH₃OH)]·CH₃CN (1) and [Zn₄Pr₂L₄(terephthalate)₂]·(NO₃)₂ (2) (H₂L = bis(3-methoxysalicylaldehyde-3-oxopene-1,5-diamine). They have been characterized by elemental analysis, UV-Vis and IR spectroscopy, and single-crystal X-ray diffraction. Structural analysis revealed that 1 has a heterodinuclear structure, with Zn(II) in the inner cavity generated by deprotonated ligands L^2- and Pr(III) in the larger outer cavity. Cluster 2 is a heterohexanuclear structure, in which the Pr(III) bridges two [ZnL] to form a heterotrinuclear secondary unit [Zn₂PrL₂], and then two terephthalates connect two secondary units to form a heterohexanuclear cluster structure. The solid-state fluorescence properties of clusters and ligand show that there are not only slightly blue-shifted fluorescence peak of ligand, but also characteristic fluorescence peaks of Pr(III) ions in the two clusters: 615 nm (³P₀→³H₆) for 1, 609 nm (¹D₂→³H₄) and 646 nm (³P₀→³F₂) for 2, respectively. In the two clusters, the difference of ion fluorescence peaks is attributed to the symmetry difference of coordination geometric environment of Pr(III).

KEYWORDS:

• Synthesis
• crystal structure
• chain-shaped ether Schiff base
• d-f heteronuclear cluster
• fluorescence

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Natural Science Foundation of Gansu Province (Grant No. 21JR7RA298).