The compound (bpy)(2)Mn-III(mu-O)(2)Mn-IV(bpy)(2), a structural model relevant for the photosynthetic water oxidation complex, was coupled to single Cr-VI charge-transfer chromophores in the channels of the nanoporous oxide AIMCM-41. Mn K-edge EXAFS spectroscopy confirmed that the di-mu-oxo dinuclear Mn core of the complex is unaffected when loaded into the nanoscale pores. Observation of the 16-line EPR signal characteristic of Mn-III(mu-O)(2)Mn-IV demonstrates that the majority of the loaded complexes retained their nascent oxidation state in the presence or absence of Cr-VI centers. The FT-Raman spectrum upon visible light excitation of the Cr-VI-O-II -> Cr-V-O-I ligand-to-metal charge transfer reveals electron transfer from Mn-III(mu-O)(2)Mn-IV (Mn-O stretch at 700 cm(-1)) to Cr-VI, resulting in the formation of Cr-V and Mn-IV(mu-O)(2)Mn-IV (Mn-O stretch at 645 cm(-1)). All initial and final states are directly observed by FT-Raman or EPR spectroscopy, and the assignments are corroborated by X-ray absorption spectroscopy measurements. The endoergic charge separation products (Delta E-circle = -0.6 V) remain after several minutes, which points to spatial separation of Cr-V and Mn-IV(mu-O)(2)Mn-IV as a consequence of hole (O-I) hopping as a major contributing mechanism. This is the first observation of visible light-induced oxidation of a potential water oxidation complex by a metal charge-transfer pump in a nanoporous environment. These findings will allow for the assembly and photochemical characterization of well-defined transition metal molecular units, with the ultimate goal of performing endothermic, multielectron transformations that are coupled to visible light electron pumps in nanostructured scaffolds.