Near-Infrared and Visible Photoactivation to Uncage Carbon Monoxide from an Aqueous-Soluble PhotoCORM

Abstract

Multiphoton excitation allows one to access high energy excited states and perform valuable tasks in biological systems using tissue penetrating near-infrared (NIR) light. Here we describe a new photoactive manganese tricarbonyl complexes incorporating the ligand 4'-p-N,N-bis(2-hydroxyethyl)benzyl-2,2':6',2''terpyridine (TPYOH), which can serve as an antenna for two photon NIR excitation. Solutions of Mn(CO)3(TPYOH)X (X = Bror CF3SO3-) complexes are very photoactive towards CO release under visible light excitation (405 nm, 451 nm). The same responses were also triggered by multiphoton excitation at 750 nm and 800 nm. In this context, we discuss the potential applications of these complexes as visible/near-IR light photoactivated carbon monoxide releasing moieties (photoCORMs). We also report the isolation and crystal structures of the TPYOH complexes Mn(TPYOH)Cl2 and [Mn(TPYOH)2](CF3SO3)2, to illustrate possible photolysis product(s).

Synthesis, characterization and photoinduced CO-release by manganese(i) complexes

“…In dichloromethane the compounds lose the CO with no defined intermediate, in acetonitrile, all compounds form a third and lower intensity band around 1870-1850 cm -1 , associated with the formation of a biscarbonyl intermediate. 49,53,54,56 The relative low intensity of the biscarbonyl intermediate may be due to fast oxidation of the compounds once they begin to lose the CO, as previously reported. 47,55 On comparing the relative areas after photoexcitation, all compounds lose all three CO molecules in both media.…”

Release of CO and Production of 1O2 from a Mn-BODIPY Photoactivated CO Releasing Molecule with Visible Light

“…One of the main challenges in designing an efficient photoCORM is activation by light in the phototherapeutic window (600–950 nm). To date, various strategies, including ancillary ligand modifications, , multiphoton excitation, , mixing with a triplet-state photosensitizer, quantum dots, upconverting nanoparticles, or as previously reported by our group, coupling with a visible light absorbing metal complex, and so forth, have been employed to activate the photo-CO dissociation under visible and NIR irradiation. Alternatively, the use of dye photosensitizers as light-harvesting components of the design allows for visible light-activated photoCORMs …”

Excited-state dynamics of [Mn(im)(CO)3(phen)]+: PhotoCORM, catalyst, luminescent probe?

“…Recent experimental research interest in this field leads to the synthesis of novel compounds, functionalized from early Re(I) and Mn(I) -diimine complexes, suitable for bio-medical applications. [7][8][9][10] Within the context of CO2 reduction catalysis, ultrafast spectroscopy of [MnBr(CO)3(R-bpy)] (R-bpy = 4,4'-disubstituted 2,2'-bipyridyl; R= t Bu, H, CF3, NO2) has been investigated in acetonitrile. This recent study points to a time constant for CO release of 460-680 fs, sensitive to the R substituent, subsequent solvent coordination occurring within 18 to 39 ps time scale.…”