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Hemilabile Coordination Complexes as Fluorescent Chemosensors The Groundwork: RuPOMe

Hemilabile Coordination Complexes as Fluorescent Chemosensors The Groundwork: RuPOMe. Anthony Tomcykoski. Overview. Introduction Synthetic Approach Characterization Conclusions Future Work. Introduction. Hemilabile Coordination Polydentate chelates Inert and labile binding positions

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Hemilabile Coordination Complexes as Fluorescent Chemosensors The Groundwork: RuPOMe

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  1. Hemilabile Coordination Complexes as Fluorescent ChemosensorsThe Groundwork: RuPOMe Anthony Tomcykoski

  2. Overview Introduction Synthetic Approach Characterization Conclusions Future Work

  3. Introduction • Hemilabile Coordination • Polydentate chelates • Inert and labile binding positions • Phosphine-ether ligands Hemilabile coordination complex in the presence of a small polar molecule (1)

  4. Introduction • Examples of Hemilabile Ligands Tris(2,6-methoxyphenyl)phosphine P(OMe)6 Bis(2-methoxyphenyl)phenylphosphine P(OMe)2 POMe Diphenyl(2-methoxyphenyl)phosphine

  5. Introduction • Photosensitizer • [Ru(bpy)3]+2 • Long lived 3MLCT • Fluorescent Chemosensor • Molecular sensing • Monitor photophysical properties

  6. Synthetic Approach Step One: Make a suitable starting material .2 H2O Starting Material Ru(bpy)2Cl2.2H2O

  7. Synthetic Approach Step Two: Remove inner sphere chloride Introduce non- coordinating anion (BF4-) 2 Solvated bis(bipyridyl) complex

  8. Synthetic Approach Step Three: Coordinate phosphine-ether hemilabile ligand Isolate product RuPOMe

  9. Hemilabile Coordination Complexes Tolylterpyridylchromophores Tridentate Ligands RuPOMe RuP(OMe)6 Bipyridyl Chromophores Bidentate Ligands RuP(OMe)2 Ru(bpy)2P(OMe)6

  10. Characterization UV/Vis Spectroscopy Infrared Spectroscopy Emission Spectra Excited State Lifetime NMR (1H, 13C, 31P)

  11. UV/Vis SpectroscopyBipyridyl Systems MLCT energy gap varies in each complex [Ru(bpy)3](PF6)2 450nm RuCl3.nH2O 420nm Ru(bpy)2Cl2 376, 548nm [RuPOMe](PF6)2 450nm [Ru(bpy)2P(OMe)6](PF6)2 430nm in EtOH/Acet 476nm [Ru(bpy)3](PF6)2 RuCl3.nH2O Ru(bpy)2Cl2.2H2O

  12. Jablonski Diagram MLCT[Ru(bpy)3]+2 Short, sub-picosecond ISC 1MLCT Long, ~5μs S1 3MLCT T1 E Radiative Decay hν Nonradiative Decay • Interested in Monitoring • 3MLCT Lifetime • Radiative Decay or Emission S0

  13. UV/Vis SpectroscopyTolylterpyridyl Systems MLCT Bands Ru(ttpy)Cl3 440nm [Ru(ttpy)2]Cl2 486nm [RuP(OMe)6](BF4)2 460nm

  14. Emission SpectraRoom Temperature [RuPOMe](PF6)2 emission 601nm excitation 463nm [Ru(bpy)2P(OMe)6](PF6)2 emission 505nm excitation 430nm RuP(OMe)6](BF4)2 emission 413nm excitation 343nm

  15. Excited State Lifetime [Ru(bpy)3]+2  = 5µs (77K, literature)  = 132.4ns (Room Temperature, CH3CN, experimental) emission 610nm RuPOMe  = 319ns emission 601nm • Conclusion: • Room temperature lifetimes are inconsistent • The lifetime of tolylterpyridine ruthenium complexes are on the order of picoseconds

  16. NMR Studies • 1H NMR • Methoxy proton shifts • Observe bound and unbound ligand signal • 13C NMR • Signal:Noise low, numerous peaks • 31P NMR • High number of scans (6400 scans) • Unique 31P resonances with analyte complexation • Long T1 Relaxation (PPh3=13.369s, POMe=18.396s)

  17. 1H NMR 2,2’-bipyridine free ligand Aromatics > 7ppm POMe free ligand -OCH3 3.70ppm [RuPOMe](PF6)2 -OCH3 2.05ppm

  18. 31P NMR [RuPOMe](PF6)2 [2.85 x 10-3M] in Acetone-d6 56ppm Ether Bound -143ppm(septet) PF6- POMe free ligand -14.45ppm [RuP(OMe)6](BF4)2 [3.0 x 10-3M] in Acetone-d6 15.5ppm Ether bound -63.5ppm(d) undesired product -68.5ppm(d) undesired product P(OMe)6 free ligand -70.8ppm

  19. Conclusions • [RuPOMe](PF6)2 successfully synthesized and characterized • [RuP(OMe)2] and [RuP(OMe)6] require different synthetic approach • Tolylterpyridine is not ideal as a chromophoric ligand • MLCT electronic state observed for bipyridyl and tolylterpyridylchromophores • Complexes are luminescent, but minimal at room temperature

  20. Future Work • Concentration Dependence • Analyte selectivity titrations • Low Temperature (77K) Photophysics • 31P NMR in Determining Equilibrium • Quantum Yield Measurements • Use Fluorescent Polymer Units as Hemilabile Ligands

  21. Acknowledgements • Jones’ Group • Dr. Jones, Dr. Martin, Dr. Flynn • Jasper, Wenrong, Catherine, Sherryllene, Dickson, Peter • Undergraduates • Dr. Jürgen Schulte • Chemistry Department • Binghamton University

  22. References • Rogers, C.W.; Zhang, Y.; Patrick, B.O.; Jones, W.E.; Wolf, M.O. Inorg. Chem. 2002, 41, 1162-1169 • Kalyanasundaram, K. Photochemistry of Polypyridine and Porphyrin Complexes; Academic Press: London, 1992. • Angell, S.E.; Zhang, Y.; Rogers, C.W.; Wolf, M.O.; Jones, W.E.; Inorg. Chem. 2005, 44, 7377-7384 • Alary, F.; Heully, J.L.; Bijeire, L.; Vicendo, P. Inorg. Chem. 2007, 46, 3154-3165. • Wang, J.; Fang, Y.Q.; Hanan, G.S.; Loiseau, F.; Campagna, S. Inorg Chem. 2005, 44, 5-7. • Rogers, C.W.; Wolf, M.O. Chem. Comm. 1999, 2297-2298. • Angell, S.E., Rogers, C.W.; Zhang, Y.; Wolf, M.O.; Jones, W.E.; Coordination Chemistry Reviews. 2006, 250, 1829-1841. • Demas, J.N.; Adamson, A.W. J. Am. Chem. Soc.1971, 93, 1800-1801

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