An excellent colorimetric and "turn off" fluorescent probe for tetrahydrofuran based on a luminescent macrocyclic samarium(iii) complex.

In this paper we report a novel probe based on a luminescent 23-membered [1 + 1] Schiff-base macrocyclic mononuclear Sm(iii) complex Sm-2e, originating from the dialdehyde H2Qe and 1,2-bis(2-aminoethoxy)ethane precursors, which is synthesized by the Sm(iii) ion template method. X-ray structural analyses confirm that each ten-coordinate Sm(iii) center with the coordination geometry of a distorted bicapped square antiprism is fully encapsulated by a flexible macrocyclic ligand H2L2e to form a "lasso-type" architecture, and this architecture could enable efficient energy transfer in various solvents confirmed by long lifetimes (33.5-65.2 µs) and high quantum yields (0.23-0.76%) of the Sm(iii) ion. Simultaneously, complex Sm-2e could serve as a probe for sensing organic solvents. Particularly, this complex probe Sm-2e exhibits a highly selective, rapid and sensitive response to tetrahydrofuran (THF), which is easily distinguished by a large absorption shift, even visible to the naked eye, and complete fluorescence quenching. Moreover, the limit of detection for THF is about 0.20% determined by titration experiments, and good selectivity for THF could still be realized in mixture solvents. Consequently, this colorimetric and "turn off" fluorescent probe Sm-2e could be a valuable candidate as a sensor material for sensing THF which has been rarely reported.

Series of Highly Luminescent Macrocyclic Sm(III) Complexes: Functional Group Modifications Together with Luminescence Performances in Solid-State, Solution, and Doped Poly(methylmethacrylate) Film.

Here, we report our trials to regulate the luminescence performance of the macrocyclic samarium(III) complex and prepare four excellent luminescent Sm(III) complex-doped poly(methylmethacrylate) (PMMA) composites. Four 23-membered [1 + 1] Schiff-base macrocyclic mononuclear Sm(III) complexes, Sm-2 a -Sm-2 d , originating from dialdehydes with different pendant arms and 1,2-bis(2-aminoethoxy)ethane, have been constructed by the template method. Crystal structures reveal that every Sm(III) ion with the coordination geometry of a distorted bicapped square antiprism is capsulated by the macrocyclic cavity environment forming the "lasso-type" protection. Relative photophysical properties of macrocyclic Sm(III) complexes are carefully investigated in solid-state, methanol solution, and doped PMMA film, and all these show characteristic emissions of the Sm(III) ion associated with satisfactory lifetimes and quantum yields in all media, which could be comparable to reported outstanding examples. Especially, the luminescence performance for this type of Sm(III) complex could be regulated in the solid state by the use of different functional groups in the pendant arm while it is not achieved in solution and the doped PMMA composite. High emitting and air-stable plastic materials could be obtained when these Sm(III) complexes are doped in PMMA with 0.1 wt % mixing ratio, and the corresponding maximum lifetime and quantum yield are 61.2 µs and 0.63% in the case of complex Sm-2 a , respectively. We believe that these highly luminescent "lasso-type" Sm(III) complexes and doped PMMA composites are valuable references in the design of luminescent lanthanide(III) hybrid materials.