This invention pertains to light emitting materials comprising novel ortho-metalated transition metal complexes [C^N]2ML, comprising chelate monoionic ligands (L), also called ancillary ligands. It has been surprisingly found that when the ancillary ligand comprises a substituted aromatic ring bearing a substituent possessing adequate electron-donating properties, said ligand (L) advantageously participates in the emission process, significantly shifting emission towards higher energies (blue-shift) and enabling appreciable improvement of the emission efficiency of complexes [C^N]2ML. Still objects of the invention are the use of said light emitting materials and organic light emitting device comprising said light emitting material.