A novel class of efficient antenna complexes of Tb3+ based on the use of 3-phenyl-4-acyl-5-isoxazolone ligands has been synthesized and evaluated their photophysical properties. The new heterocyclic -diketonate complexes of Tb3+ exhibit high green luminescence efficiency in solid state with high quantum yields in the range 59 -72 %. The quantum yield of the designed antenna complexes further enhanced when doped into poly--hydroxybutyrate (PHB) polymer films. The fact that the luminescent efficiency of doped films enhanced (quantum yields between 74 – 86%) compared with the precursor samples revealed that the polymer matrix acts as a co-sensitizer for Tb3+centers (J. Mater. Chem. 2009, 19, 5179–5187 ).