title: Rhenium(I) polypyridine diamine complexes as intracellular phosphorogenic sensors: synthesis, characterization, emissive behavior, biological properties, and nitric oxide sensing.
abstract: We report the development of a series of rhenium(I) polypyridine complexes appended with an electron-rich diaminoaromatic moiety as phosphorogenic sensors for nitric oxide (NO). The diamine complexes [Re(N^N)(CO)3 (py-DA)][PF6 ] (py-DA=3-(N-(2-amino-5-methoxyphenyl)aminomethyl)pyridine; N^N=1,10-phenanthroline (phen) (1 a), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4 -phen) (2 a), 4,7-diphenyl-1,10-phenanthroline (Ph2 -phen) (3 a)) have been synthesized and characterized. In contrast to common rhenium(I) diimines, these diamine complexes were very weakly emissive due to quenching of the triplet metal-to-ligand charge-transfer ((3) MLCT) emission by the diaminoaromatic moiety through photoinduced electron transfer (PET). Upon treatment with NO, the complexes were converted into the triazole derivatives [Re(N^N)(CO)3 (py-triazole)][PF6 ] (py-triazole=3-((6-methoxybenzotriazol-1-yl)methyl)pyridine; N^N=phen (1 b), Me4 -phen (2 b), Ph2 -phen (3 b)), resulting in significant emission enhancement (I/I0 ≈60). The diamine complexes exhibited high reaction selectivity to NO, and their emission intensity was found to be independent on pH. Also, these complexes were effectively internalized by HeLa cells and RAW264.7 macrophages with negligible cytotoxicity. Additionally, the use of complex 3 a as an intracellular phosphorogenic sensor for NO has been demonstrated.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (P.R. China), Fax: (852) 3442-0522.
authors.forename: Alex Wing-Tat
authors.initials: AW
authors.lastname: Choi
authors.forename: Vicki Man-Wai
authors.initials: VM
authors.lastname: Yim
authors.forename: Hua-Wei
authors.initials: HW
authors.lastname: Liu
authors.forename: Kenneth Kam-Wing
authors.initials: KK
authors.lastname: Lo
mesh_terms: D000818:Animals; D003959:Diamines / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D009569:Nitric Oxide / Q000032:analysis*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D010618:Phenanthrolines / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D012211:Rhenium / Q000737:chemistry*
chemical_list: D003959:Diamines; D009942:Organometallic Compounds; D010618:Phenanthrolines; D011725:Pyridines; D009569:Nitric Oxide; D012211:Rhenium
keywords: imaging agents; luminescence; nitric oxide; rhenium; sensors