Crystal structures and vibrational and electronic spectroscopic data are reported for europium(III) complexes with 5(or 4)-R-1,10-phenanthroline (phen) ligands (R = chloro, methyl, nitro, amino). All complexes comprise a 10-coordinate Eu 3+ ion with three chelating nitrato anions and two bidentate phen ligands. The crystal structures are of three distinct types with space groups C2/c, P2 1 /n and P1. The roomtemperature emission spectra are dominated by the forced electric dipole 5 D 0 Ǟ 7 F 2 emission of Eu 3+ . The excitation spectra show that the triplet donor state of the nitro-substituted complex has a lower energy than the other complexes and the lower luminescence quantum efficiency of this complex is rationalized. The emission spectra recorded at 10 K