Europium(III) complexes that are the anisometric analogues of a well-known Eu(DBM)(3)Phen (DBM = dibenzoylmethane; Phen = 1,10-phenanthroline) complex were synthesized. Quantum chemical calculations of the excited states of new Eu(III) complexes and some conjugated polymers showed that poly(N-vinylcarbazole) provides the most efficient energy transfer in polymer films doped with synthesized Eu(III) complexes. These new composite films were prepared, and their luminescence properties were studied. The results of experimental data confirmed theoretical prediction about significant influence introduced in molecular structure long terminal alkyl chains and cyclohexane on the luminescence efficiency of "Ln(III)-polymer" composite. As the result a substantial contribution of complex anisometry to the luminescence efficiency of composite was revealed due to the increase of the complex limit concentration before Self-quenching more than twofold.