title: Synthesis, characterization, photophysical properties, and biological labeling studies of a series of luminescent rhenium(I) polypyridine maleimide complexes.
abstract: We report the synthesis, characterization, and photophysical properties of a series of rhenium(I) polypyridine maleimide complexes [Re(N-N)(CO)(3)(py-3-mal)](CF(3)SO(3)) [N-N = 1,10-phenanthroline, phen (1), 2,9-dimethyl-1,10-phenanthroline, 2,9-Me(2)-phen (2), 3,4,7,8-tetramethyl-1,10-phenanthroline, 3,4,7,8-Me(4)-phen (3), 4,7-diphenyl-1,10-phenanthroline, 4,7-Ph(2)-phen (4), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 2,9-Me(2)-4,7-Ph(2)-phen (5), 2,2'-biquinonine, biq (6); py-3-mal = N-(3-pyridyl)maleimide]. The X-ray crystal structure of complex 2 has been investigated. Upon excitation, the complexes exhibit intense and long-lived photoluminescence in fluid solutions at 298 K. The emission wavelengths range from 514 to 654 nm, and the emission lifetimes fall in the microsecond time scale. The luminescence is assigned to originate from a metal-to-ligand charge-transfer MLCT [dpi(Re) --> pi*(diimine)] triplet excited state. As the maleimide group can react with the sulfhydryl group to form a stable thioether moiety, these complexes have been used as thiol-specific luminescent labels for a thiolated oligonucleotide, glutathione, and bovine serum albumin and human serum albumin. The photoluminescence properties of the labeled biological species have also been investigated.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, PR China. bhkenlo@cityu.edu.hk
authors.forename: Kenneth Kam-Wing
authors.initials: KK
authors.lastname: Lo
authors.forename: Wai-Ki
authors.initials: WK
authors.lastname: Hui
authors.forename: Dominic Chun-Ming
authors.initials: DC
authors.lastname: Ng
authors.forename: Kung-Kai
authors.initials: KK
authors.lastname: Cheung
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D018360:Crystallography, X-Ray; D005454:Fluorescence Polarization; D005978:Glutathione / Q000737:chemistry; D006801:Humans; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008298:Maleates / Q000737:chemistry; D008301:Maleimides / Q000138:chemical synthesis* / Q000737:chemistry*; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D010777:Photochemistry; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013873:Thionucleotides / Q000737:chemistry
chemical_list: D008024:Ligands; D008298:Maleates; D008301:Maleimides; C446659:N-(3-pyridyl)maleamic acid; D009942:Organometallic Compounds; D011725:Pyridines; D012709:Serum Albumin; D013438:Sulfhydryl Compounds; D013873:Thionucleotides; D012710:Serum Albumin, Bovine; D012211:Rhenium; D005978:Glutathione