Langmuir–Schaefer films based on highly hydrophobic Eu3+ tetrakis-β-diketonate complexes containing amphiphilic counterions

Abstract Langmuir-Schaefer (LS) films based on [Q][Eu(dbm)4)] complexes — where dbm- = 1,3-diphenyl-1,3-propanedionate, Q = C26H56N+ (Q1), C19H42N+ (Q2), or C17H38N+ (Q3) — using amphiphilic counterions (Q) to organize the luminescent anionic complex on the subtract have been investigated. The amphiphilic counterions play an important role in the film fabrication by increasing the surface homogeneity and deposition quality as the carbonic chain increases, especially for the [Q1][Eu(dbm)4)] film, which showed root mean square surface roughness of 37.8 nm. All films displayed the characteristic Eu3+ red-light emission under excitation at 367 nm, and the best intrinsic emission quantum yield was achieved for the [Q1][Eu(dbm)4)] film (27.5 %), confirming that the counterion also influences the luminescent features of the films due to changes in the anionic complex conformation compared to the respective bulk complexes.