title: A cyclometalated iridium(III) complex with enhanced phosphorescence emission in the solid state (EPESS): synthesis, characterization and its application in bioimaging.
abstract: Iridium(III) complexes with intense phosphorescence in solution have been widely applied in organic light-emitting diodes, chemosensors and bioimaging. However, little attention has been paid to iridium(III) complexes showing weak phosphorescence in solution and enhanced phosphorescence emission in the solid state (EPESS). In the present study, two β-diketonate ligands with different degrees of conjugation, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HL1) and 1-phenyl-3-methyl-4-phenylacetyl-5-pyrazolone (HL2), have been synthesized to be used as ancillary ligands for two iridium(III) complexes, Ir(ppy)(2)(L1) and Ir(ppy)(2)(L2) (Hppy = 2-phenylpyridine). The two complexes have been characterized by single-crystal X-ray crystallography, (1)H NMR and elemental analysis. Interestingly, Ir(ppy)(2)(L1) is EPESS-active whereas Ir(ppy)(2)(L2) exhibits moderately intense emission both in solution and as a neat film, indicating that the degree of conjugation of the β-diketone ligands determines the EPESS-activity. The single-crystal X-ray analysis has indicated that there are π-π interactions between the adjacent ppy ligands in Ir(ppy)(2)(L1) but not in Ir(ppy)(2)(L2). Finally, EPESS-active Ir(ppy)(2)(L1) has been successfully embedded in polymer nanoparticles and used as a luminescent label in bioimaging.
authors.affiliation: Department of Chemistry, Fudan University, Shanghai 200433, PR China.
authors.forename: Huazhou
authors.initials: H
authors.lastname: Wu
authors.forename: Tianshe
authors.initials: T
authors.lastname: Yang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhao
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Chunyan
authors.initials: C
authors.lastname: Li
authors.forename: Fuyou
authors.initials: F
authors.lastname: Li
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray / Q000379:methods; D003952:Diagnostic Imaging / Q000295:instrumentation; D004563:Electrochemistry / Q000379:methods; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010777:Photochemistry / Q000379:methods; D011108:Polymers / Q000737:chemistry; D011720:Pyrazoles / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D011789:Quantum Theory; D012996:Solutions / Q000737:chemistry
chemical_list: C558479:1-phenyl-3-methyl-4-benzoyl-5-pyrazolone; D001672:Biocompatible Materials; D056831:Coordination Complexes; D008024:Ligands; D009942:Organometallic Compounds; D011108:Polymers; D011720:Pyrazoles; D011725:Pyridines; D012996:Solutions; C058324:2-phenylpyridine; D007495:Iridium