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Synthesis and Study of Polyazine Bridged Mixed Metal Dyads: Electrochemical, Photophysical, and Photochemical Properties of a New Supramolecular Architecture
| Content Provider | Semantic Scholar |
|---|---|
| Author | Zigler, David F. |
| Copyright Year | 2008 |
| Abstract | A series mixed metal supramolecular complexes were synthesized and studied by electrochemistry, photophysics and photochemistry. The complexes consisted of a single Ru or Os polyazine light absorber bound to a cis-RhCl2 moiety through a polyazine bridging ligand. A related class of supramolecule is known to perform photoinitiated electron collection, photocatalysis of hydrogen from water, DNA photomodification and is known to kill mammalian cells; all with visible light irradiation. The complexes studied herein, [(bpy)2Ru(bpm)RhCl2(phen)](PF6)3, [(bpy)2Ru(dpp)RhCl2(phen)](PF6)3, [(bpy)2Os(dpp)RhCl2(phen)](PF6)3, and [(tpy)OsCl(dpp)RhCl2(phen)](PF6)2 were synthesized in moderate yields (54-84%) by reaction of the appropriate monometallic visible light absorbing subunit with a slight excess of K[(phen)RhCl4]·3H2O (bpy = 2,2'-bipyridine, bpm = 2,2'bipyrimidine, 1,10-phenanthroline, dpp = 2,3-bis(2-pyridyl)pyrazine, and tpy = 2,2':6',2"terpyridine). Voltammetric analysis of [(bpy)2Ru(bpm)RhCl2(phen)](PF6)3 revealed a reversible oxidation at 1.76 V (vs. Ag/AgCl) (Ru). A reversible reduction at −0.14 V (bpm), and quasi-reversible reductions at −0.77 V and −0.91 V each corresponded to a one electron process, bpm, Rh and Rh. The electrochemistry of [(bpy)2Ru(dpp)RhCl2(phen)](PF6)3 showed a reversible oxidation at 1.61 V (Ru), and quasi-reversible reductions at −0.39 V, −0.74 V and −0.98 V. The first two reductive couples corresponded to two electrons, consistent with Rh reduction. [(bpy)2Os(dpp)RhCl2(phen)](PF6)3, and [(tpy)OsCl(dpp)RhCl2(phen)](PF6)2 each exhibited reductions similar to the dpp bridged Ru,Rh dyad, but with Os based oxidations at 1.24 V and 0.83 V, respectively. The complexes [(bpy)2Ru(bpm)RhCl2(phen)](PF6)3 and [{(bpy)2Ru(bpm)}2RhCl2](PF6)5 display Ru(dπ)→bpm(π*) CT (MLCT) transitions at 581 nm and at 594 nm, respectively. The dpp bridged Ru,Rh bimetallic and Ru,Rh,Ru trimetallic display Ru(dπ)→dpp(π*) CT transitions at 509 nm and 518 nm, respectively. Similarly, [(bpy)2Os(dpp)RhCl2(phen)](PF6)3 absorbs strongly at 520 nm versus 534 nm for [{(bpy)2Os(dpp)}2RhCl2](PF6)5, both with low energy tails at 800 nm indicative of Os centered MLCT transitions. Overlapping Os(dπ)→dpp(π*) and Os(dπ)→tpy(π*) transitions occur at 536 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://theses.lib.vt.edu/theses/available/etd-11042008-143805/unrestricted/Zigler_ETD_3.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
