LAUSR

Abstract Herein a 23-membered macrocyclic mononuclear Sm(III) complex Sm-2f has been designed and synthesized via the Schiff-base cyclocondensation between extended dialdehyde H2Qf and 1,2-bis(2-aminoethoxy)ethane in the presence of Sm(NO3)3. The analyses of single-crystal structure reveal that central ten-coordinate Sm(III) ion is capsulated by the macrocyclic cavity microenvironment forming the “lasso-type” protection. The sensing ability of complex Sm-2f is also carefully evaluated for four alkali metal ions in mixture of methanol and water. Interestingly, this complex could serve as a colorimetric molecular probe and selectively recognize Li(I) ion in solution, easily distinguished by naked eye, whether or not other alkali metal ions are present, which is derived from the formation of a new species containing a probe molecule and one Li(I) ion. The limit of detection for Li(I) ion is calculated as 1.147 mM determined by UV–vis titration experiments, and the sensing process is rapid within 60 s. Moreover, this probe also shows satisfactory performances for determining Li(I) ion content in the psychosis drug. The special architecture in macrocyclic complex Sm-2f as well as the combination of size and electronic effects of Li(I) ion are believed to play important roles for this convenient method of sensing Li(I) ions in solution.