Dual vis-NIR emissive bimetallic naphthoates of Eu–Yb–Gd: a new approach toward Yb luminescence intensity increase through Eu → Yb energy transfer

(n = 0, 1) were obtained and thoroughly investigated. Homoligand naphthoates of the new phase were obtained as anhydrous powders from water. The photophysical properties of the obtained compounds were studied in detail. The first example of Eu-to-Yb energy transfer was found in these systems. Careful selection of the metal ratio allowed a dual vis-NIR emissive complex with a ytterbium quantum yield of 1.5% to be obtained.