The First Example of Near-Infrared 4f Luminescence of Sandwich-Type Lanthanide Phthalocyaninates

A detailed analysis of photophysical characteristics of mono-, double-and triple-decker complexes of Er-III, Yb-III and Lu-III with 2,3,9,10,16,17,24,25-tetrakis(15-crown-5) phthalocyanine (L) was performed. The values of the quantum yields and the rate constants of molecular fluorescence and intersystem crossing of the compounds were estimated. It was discovered that the solutions of the sandwich Er-III and Yb-III double-and triple-decker phthalocyaninates possess 4f luminescence in near-infrared range (NIR) at 1540 nm and 980 nm, respectively. It was demonstrated that Yb-III mono-phthalocyaninate also exhibits 4f luminescence. The proposed mechanism of excitation energy transfer is discussed.