title: Manganese carbonyls bearing tripodal polypyridine ligands as photoactive carbon monoxide-releasing molecules.
abstract: The recently discovered cytoprotective action of CO has raised interest in exogenous CO-releasing materials (CORMs) such as metal carbonyls (CO complexes of transition metals). To achieve control on CO delivery with metal carbonyls, we synthesized and characterized three Mn(I) carbonyls, namely, [Mn(tpa)(CO)(3)]ClO(4) [1, where tpa = tris(2-pyridyl)amine], [Mn(dpa)(CO)(3)]Br [2, where dpa = N,N-bis(2-pyridylmethyl)amine], and [Mn(pqa)(CO)(3)]ClO(4) [3, where pqa = (2-pyridylmethyl)(2-quinolylmethyl)amine], by crystallography and various spectroscopic techniques. All three carbonyls are sensitive to light and release CO when illuminated with low-power UV (5-10 mW) and visible (λ > 350 nm, ~100 mW) light. The sensitivity of 1-3 to light has been assessed with respect to the number of pyridine groups in their ligand frames. When a pyridine ring is replaced with quinoline, extended conjugation in the ligand frame increases the absorptivity and makes the resulting carbonyl 3 more sensitive to visible light. These photosensitive CORMs (photoCORMs) have been employed to deliver CO to myoglobin under the control of light. The superior stability of 3 in aqueous media makes it a photoCORM suitable for inducing vasorelaxation in mouse aortic muscle rings.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA.
authors.forename: Margarita A
authors.initials: MA
authors.lastname: Gonzalez
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Yim
authors.forename: Stephanie
authors.initials: S
authors.lastname: Cheng
authors.forename: Amie
authors.initials: A
authors.lastname: Moyes
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Hobbs
authors.forename: Pradip K
authors.initials: PK
authors.lastname: Mascharak
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D002248:Carbon Monoxide / Q000008:administration & dosage* / Q000494:pharmacology; D018360:Crystallography, X-Ray; D003692:Delayed-Action Preparations / Q000737:chemistry*; D006736:Horses; D008024:Ligands; D008027:Light; D008297:Male; D008345:Manganese / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D008958:Models, Molecular; D009211:Myoglobin / Q000378:metabolism; D011725:Pyridines / Q000737:chemistry*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D003692:Delayed-Action Preparations; D008024:Ligands; D009211:Myoglobin; D011725:Pyridines; D008345:Manganese; D002248:Carbon Monoxide