| Popis: |
In this work, we report the synthesis, photophysics, and electrochemistry of a new array of trinuclear complexes, [(bpy)2Os(d-HIm-t)M(t-HIm-d)Os(bpy)2]6+ (M = FeII, RuII, and OsII), based on a previously reported bipyridine-terpyridine type bridge (d-HIm-t). Photophysical behavior of in situ generated trinuclear OsZnOs complex {[(bpy)2Os(d-HIm-t)Zn(t-HIm-d)Os(bpy)2]6+} was also investigated to understand the complicated photophysics of trinuclear array. Complexes display very rich redox properties demonstrating multiple metal-based oxidation and ligand-based reduction couples. The triads exhibit strong absorption throughout the entire UV-vis spectral region and also emit in the near-infrared domain (NIR) with a sufficiently long lifetime at ambient temperature. Intercomponent energy transfer, either from the periphery to the center or from the center to the periphery, depending upon the relative position of metals, was convincingly demonstrated through steady-state emission and lifetime measurements of the triads together with respective model complexes. Interestingly, Fe2+ does not worsen the emission behavior of the OsFeOs system to a great extent. Present trinuclear complexes act as a visible light absorbing antenna by funneling the absorbed light to the subunit(s) with the lowest energy excited state. |
