[en] Two types of new Ln³⁺ chelates, phosphoro- and sulfono-derivatives of beta-diketones and Lewis base ligands were obtained and characterized by the high resolution photoluminescence spectroscopy at 293 and 77 as well as by luminescence decay times. The new type of phosphors shows very strong emission after excitation in the UV range within the ligand bands. The dynamics of the excited state will be discussed. The paths of the energy transfer (ET) are analyzed and mechanism of this process is proposed. The silica gels containing investigated complexes with silver particles were obtained and the role of silver plasmons on spectroscopic properties is displayed. - Highlights: • Spectral characteristic of new type of lanthanide chelates: Na[Ln(SP)₄] and [Ln(SP)₃L]. • Preparation of the energy-transfer (E-T) diagram. • Analysis of the possible pathways of energy transfer and their mechanism. • Application of chelates incorporated in sol–gel codoped by Ag particles.