Dr. R. P. Thummel

Randolph Thummel
Professor of Chemistry

Office: 123 Lamar Fleming
Phone: 713-743-2734
Lab: 713-743-2733
Fax: 713-743-2709
E-mail: thummel@uh.edu
University of Houston
Department of Chemistry
136 Fleming Building
Houston, Texas 77204-5003

Research Publications
3-D X-ray Drawings
Organic Chemistry 3331
Photo Gallery
Phi Beta Delta

Crystal Beach, April 2005. Front: Dr. Ruifa Zong, Ahmet Kukrek. Rear: Gang Zhang, RT,
Dr. Yuanjun Hou, Richard Hammitt, Dr. Thomas Bark, Ajay Singh. Missing: Dr. Dong Wang.

Research Interests: Organic and Supramolecular Chemistry
     Our main interest is the design and synthesis of novel ligand systems. Ligands, in the broadest sense, are species which interact with other species through the formation of non-covalent bonds: metal-ligand complexes are one good example. In that context, we have prepared a wide variety of derivatives of 2,2'-bipyridine, 2,2';6,2"-terpyridine and 1,10-phenanthroline (see 3D x-rays on homepage). In many cases we have used polymethylene bridging to control the conformation of the ligand as in the diphenanthrolines 1. The related terphenanthroline forms a helical trinuclear complex with Cu(I) which resembles the coiling of DNA (Figure 1). Aza-aromatic rings can be arranged in a parallel fashion to provide rigid syn-orthocyclophanes that complex two metals in a layered orientation. We have prepared chiral steroidal phenanthrolines such as 2 as well as a trans-chelating bipyridine analogue 3.

     Cavity shaped molecules possessing indole subunits can accept neutral organic guests by taking advantage of a well organized hydrogen-bonding assembly as shown by structure 4. Hosts of this type show excellent potential for binding a variety of biologically important molecules such as amides and ureas. Bridged bithiazolium and biimidazolium salts undergo the reversible transfer of one or two electrons to provide radical cations or neutral species such as 5. The redox properties and donor-acceptor abilities of these species can be tuned by varying the length of their polymethylene bridges.
     More recently we have become interested in using ligand design for the chemical utilization of solar energy. We are developing a combinatorial approach to the synthesis of new photosensitizers for semi-conductor based solar cells. We have also synthesized a new family of ruthenium catalysts that very efficiently convert water into dioxygen. Attempts are underway to make this process photocatalytic, leading to a practical system for solar water decomposition.

Figure 1. Trinuclear Cu(I)
complex of terphenanthroline.
Figure 2. A dinuclear Ru(II) catalyst
which can efficiently oxidize water.

Recent Research Publications
1. Ligand Design and Metal Complex Chemistry
"Synthetic Approaches to Polypyridyl Bridging Ligands with Proximal Multidentate Binding Sites," Zong, R.; Wang, D.; Hammitt, R.; Thummel, R. P. J. Org. Chem. 2006, 71, 1676-175.
"Photosensitizers Containing the 1,8-Naphthyridyl Moiety and their Use in Dye Sensitized Solar Cells," Kukrek, A.; Wang, D.; Hou, Y.; Zong, R.; Thummel, R. Inorg. Chem. 2006, 45, 10131-T10137.
"[1,10]-Phenanthrolin-2-yl Ketones and their Coordination Chemistry," Bark, T. G.; Thummel, R. P. Inorg. Chem. 2005, 44, 8733-8739.
"2,2’;9’,2"-Terphenanthroline," Zong, R.; Thummel, R. P. Inorg. Chem. 2005, 44, 5984-5986.
"Ruthenium(II) Complexes of 1,12-Diazaperylene and their Interactions with DNA," Chouai, A.; Wicke, S.; Turro, C.; Bacsa, J.; Dunbar, K.; Thummel, R. P. Inorg. Chem. 2005, 44, 5996-6003.
"A New Family of Ru Complexes for Water Oxidation," Zong, R.; Thummel, R. P. J. Am. Chem. Soc. 2005, 127, 12802-12803.
"Enhanced Luminescence in a Pt(II) Complex Involving a Six-Membered Chelate Ring" Y.-Z. Hu, M. H. Wilson, R. Zong, C. Bonnefous, D. R. McMillin, and R. P. Thummel, JCS Dalton Trans. 2005, 354-358.
"The Design and Study of Bi[1,8]-naphthyridine Ligands as Potential Photooxidation Mediators in Ru(II) Polypyridyl Aqua Complexes" R. Zong, F. Naud, C. Segal, J. Burke, F. Wu, and R. Thummel, Inorg. Chem. 2004, 43, 6195-6202.
"Ru(II) Complexes of Di-[1,10]-phenanthrolinyl Diazines" D. Brown, R. Zong and R. P. Thummel, Eur. J. Inorg. Chem. 2004, 3269-3272.
"2,9-Di-(2'-pyridyl)-1,10-phenanthroline: a Tetradentate Ligand for Ru(II)" R. Zong and R. P. Thummel, J. Am. Chem. Soc. 2004, 126, 10800.
"The Preparation and Study of Di-(2-quinolyl)- and Di(2-[1,8]naphthyridyl)- Derivatives of Pyrimidine and Pyrazine as Bridging Ligands for Ru(II)," Brown, D.; Muranjan, S.; Thummel, R. P. Eur. J. Inorg. Chem. 2003, 3547.
"A Friedländer Approach for the Incorporation of 6-Bromoquinoline into Novel Chelating Ligands," Hu, Y.-Z.; Zhang, G.; Thummel, R. P. Organic Letters 2003, 5, 2251.
"Cu(I) Complexes of 3,3'-Polymethylene Bridged Derivatives of 2,2'-Bi-1,10-Phenan-throline," Riesgo, E. C.; Hu, Y.-Z.; Thummel, R. P. Inorg. Chem. 2003, 42, 6648-6654.
"Pyrene-Bridged Bis-phenanthroline Ligands and their Dinuclear Ruthenium(II) Complexes," Chouai, L.; Wu, F.; Jang, Y.; Thummel, R. P. Eur. J. Org. Chem. 2003, 2774.
"Bi-1,10-phenanthrolines and Their Mono-nuclear Ru(II) Complexes," Hu, Y.-Z.; Xiang, Q.; Thummel, R. P. Inorg. Chem. 2002, 41, 3423.
"Chiral 2,2'-Bipyridines, 1,10-Phenanthrolines and 2,2':6,2"-Terpyridines: Syntheses and Applications in Asymmetric Homogeneous Catalysis," Chelucci, G.; Thummel, R. P. Chem. Revs. 2002, 102, 3129.
"Di-[1,10]-phenanthrolinyl Diazines: A New Family of Bis-tridentate Chelators," Brown, D.; Muranjan, S.; Y. Jang, Y.; Thummel, R. Org. Lett. 2002, 4, 1253.
"A Unique 2:1 Complex with a trans-Chelating Bis-pyridine Ligand," Hu, Y.-Z.; Chamchoumis, C.; Grebowicz, J. S.; Thummel, R. P. Inorg. Chem. 2002, 41, 2296.
"Ru(II) Complexes of Crowded Delocalized Diimine Ligands," Wu, F.; Thummel, R. P. Inorg. Chim. Acta 2002, 327, 26.
"Friedländer Synthesis of Chiral Alkyl-Substituted 1,10-Phenanthrolines," Gladiali, S.; Chelucci, G.; Mudadu, M. S.; Thummel, R. P. J. Org. Chem. 2001, 66, 400.
"Evaluation of Diimine Ligand Exchange on Cu(I)," Bouvier, F.; Riesgo, E.; Thummel, R. P. Inorg. Chem. 2001, 40, 2541.
"Crowded Cu(I) Complexes Involving Benzo[h]quinoline: p-Stacking Effects and Long Lived Luminescent Excited States," Riesgo, E.; Bouvier, F.; Thummel, R. P.; Scaltrito, D.; Meyer, G. J. Inorg. Chem. 2001, 40, 3413.
"Cyclometallated Complexes of Ru(II) with 2-Aryl-1,10-phenanthrolines," Bonnefous, C.; Thummel, R. P. Inorganic Chem. 2001, 40, 5851.
"A Strong Enhancement of the Lanthanide-Centred Luminescence in Complexes with 4-Alkylated 2,2';6,2"-Terpyridines," Mürner, H.-R.; Chassat, E.; Thummel, R. P.; Bünzli, J.-C. G. J. Chem. Soc. Dalton Trans., 2000, 2809.
"Mono and Dinuclear Ru(II) and Os(II) Polypyridine Complexes Built Around Spiro-bridged Bis-phenanthroline ligands : Synthesis, Electrochemistry and Photophysics," Juris, A.; Prodi, L.; Harriman, A.; Ziessel, R.; Hissler, M.; El-ghayoury, A.; Riesgo, E. C. ; Thummel, R. P. Inorg. Chem. 2000, 39, 3590.
"Ru(II) Complexes of 2-Aryl-1,10-Phenanthrolines: Synthesis, Structure, and Photophysical Properties," Wu, F.; Riesgo, E. C.; Pavalova, A.; Kipp, R. A.; Schmehl, R.; Thummel, R. P. Inorganic Chemistry 1999, 38, 5620.
"Heterogeneous and Homogeneous Asymmetric Electrocatalytic Hydrogenation with Rhodium (III) Complexes Containing Chiral Polypyridyl Ligands," Moutet, J.-C.; Cho, L. Y.; Duboc-Toia, C.; Ménage, S.; Riesgo, E. C.; Thummel, R. P. New Journal of Chemistry 1999, 23, 939.
"Self Assembly of a Diphenanthrolinylpyrene-bridged Cu(I) Trimer," Bonnefous, C.; Bellec, N.; Thummel, R. P. J. Chem. Soc., Chem. Commun. 1999, 1243.
"Closely-spaced Chelating Centers: Synthesis of Novel Spiro-bridged Bis-phenanthrolines and Bis-indole Derivatives," Wu, F.; Riesgo, E. C.; Thummel, R. P.; Juris, A.; El-ghayoury, A.; Hissler, M.; Ziessel, R. Tetrahedron Letters 1999, 40, 7311.
"Sterically Hindered Phenanthrolines: Synthesis of 1,7,7-Trimethyl[2.2.1]bicycloheptano-[2,3-B]-1,10-Phenanthroline from (+)-Camphor," Chelucci, G.; Thummel, R. P. Synthetic Communications 1999, 29, 1665.
"Influence of Charge-Transfer States on the Eu(III) Luminescence in Mononuclear Triple Helical Complexes with Tridentate Aromatic Ligands," Petoud, S.; Bünzli, J.-C. G.; Glanzman, T.; Piguet, C.; Xiang, Q.; Thummel, R. P. J. Luminescence 1999, 82, 69.
"The Photophysical Behavior of d⁶ Complexes Having Nearly Isoenergetic MLCT and Ligand Localized Excited States," Baba, A. I.; Shaw, J. R.; Simon, J. A.; Thummel, R. P.; Schmehl, R. H. Coord. Chem. Revs. 1998, 171, 43.
"Insertion Reactions into Palladium-Carbon Bonds of Complexes Containing Terdentate Nitrogen Ligands. Experimental and Ab Initio Studies," Groen, J. H.; de Zwart, A.; Vlaar, M. J. M.; Ernsting, J.-M.; van Leeuwen, P. W. N. M.; Vrieze, K.; Kooijman, H.; Smeets, W. J. J.; Spek, A. L.; Budzelaar, P. H. M.; Xiang, Q.; Thummel, R. P., Eur. Chem. J. 1998, 1129.
"Diastereoselection and Photophysical Behavior in a Chiral Copper(I) Phenanthroline Complex," Riesgo, E. C.; Credi, A.; De Cola, L.; Thummel, R. P., Inorg.Chem. 1998, 37, 2145.
"Intramolecular Electronic Energy Transfer in Ru(II) Diimine Complex Donor/Pyrene Acceptor Complexes Linked by a Single C-C Bond," Simon, J. A.; Curry, S. L.; Schmehl, R. H.; Schatz, T. R.; Piotrowiak, P.; Jin, X.; Thummel, R. J. Am. Chem. Soc. 1997, 119, 11012.

2. Indole and Host-Guest Chemistry
"Detection and Structural Characterization of Clusters with Ultrashort-Lived Electronically Excited States: IR Absorption Detected by Femtosecond Multiphoton Ionization," Nosenko, Y.; Kuniski, M.; Thummel, R. P.; Kyrychenko, A.; Herbich, J.; Waluk, J.; Riehn, C.; Brutschy, B. J. Am. Chem. Soc. 2006, 128, 10000-10001.
"7-Pyridylindoles: Synthesis, Structure, and Properties," Mudadu, M. S.; Singh, A.; Thummel, R. P. J. Org. Chem. 2006, 71, 7611-7617.
"Excited State Proton Transfer in 2,9-(Di-2’-pyridyl)-4,7-di(t-butyl)carbazole," Wiosna-Salyga, G.; Dobkowski, J.; Mudadu, M. S.; Sazanovich, I.; Thummel, R. P.; Waluk, J. Chem. Phys. Lett. 2006, 423, 288-292.
"From Blue to Red: Syntheses, Structures, Electronic and Electroluminescent Properties of Tunable Luminiscent N,N-Chelate Boron Complexes," Liu, Q.-D.; Mudadu, M. S.; Thummel, R. P.; Tao, Y.; Wang, S. Chemistry of Materials, 2005, 15, 143-154.
"Intra- and intermolecular fluorescence quenching in 7-(pyridyl)indoles," Wiosna, G.; Petkova, I.; Mudadu, M. S.; Thummel, R. P.; Waluk, J. Chem. Phys. Lett., 2004, 400, 379-383.
"Conformational equilibria and photoinduced tautomerization in 2-(2’-pyridyl)pyrrole," Kijak, M.; Zielinska, A.; Chamchoumis, C.; Herbich, J.; Thummel, R. P.; Waluk, J. Chem. Phys. Lett., 2004, 400, 279-285.
"Vibrationally resolved electronic spectroscopy and theoretical studies of deuterated 2-(2'-pyridyl)indole," Nosenko, Y.; Thummel, R. P.; Mordzinski, A. Phys. Chem. Chem. Phys. 2004, 6, 363-367.
"Photoinduced double proton transfer in water complexes of 1H-pyrrolo[3,2-h]quinoline and dipyrido[2,3-a:3’,2’-i]carbazole," Kijak, M.; Zieliska, A.; Thummel, R. P.; Herbich, J.; Waluk, J. Chem. Phys. Lett. 2002, 366, 329.
"Tuning the Luminescence and Electroluminescence of Diphenylboron Complexes of 5-Substituted 2-(2'-Pyridyl)indoles," Liu, Q.; Mudadu, M. S.; Schmider, H.; Thummel, R.; Tao, Y.; Wang, S. Organometallics 2002, 21, 4743.
"In Search for Phototautomerization in Solid Dipyrido[2,3-a:3',2'-i]carbazole," Herbich, J.; Kijak, M.; Luboradzki, R.; Gil, M.; Zielinska, A.; Hu, Y,-Z.; Thummel, R. P.; Waluk, J. J. Photochem. Photobiology. 2002, 154, 61.
"Fluorescence Quenching by Pyridine and Derivatives Induced by Intermolecular Hydrogen Bonding to Pyrrole Containing Heteroaromatics," Herbich, J; Kijak, M.; Zielinska, A,; Thummel, R. P.; Waluk, J. J. Phys. Chem. 2002, 106, 2158.
"Bidentate Ligands which Contain Pyrrole in Place of Pyridine," Wu, F.; Chamchoumis, C.; Thummel, R. P. Inorganic Chem. 2000, 39, 584.
"Solvent-induced Syn-anti Rotamerization of 2-(2'-Pyridyl)indole and the Structure of its Alcohol Complexes," Kyrychenko, A.; Herbich, J.; Wu, F.; Thummel, R. P. and Waluk, J. J. Am. Chem. Soc. 2000, 122, 2818.
"Laser Studies of Pyridylindoles in Supersonic Jets," Nosenko, E.; Stepanenko, Y.; Wu, F.; Thummel, R. P.; Mordzinski, A. Chem. Phys. Lett. 1999, 315, 87.
"Role of Ground State Structure in Photoinduced Tautomerization in Bifunctional Proton Donor-acceptor Molecules: 1H-Pyrrolo[3,2-h]quinoline and Related Compounds," Kyrychenko, A.; Herbich, J.; Izydorzak, M.; Wu, F.; Thummel, R. P. and Waluk, J. J. Am. Chem. Soc. 1999, 121, 11179.
"Photoinduced Double Proton Transfer: Inter- and Intramolecular Cases," Kyrychenko, Herbich, J.; Izydorzak, M.; Gil, M.; Dobkowski, J.; Wu, F.; Thummel, R. P.; Waluk, J. Israel J. Chem. 1999, 39, 309.
"Diversity of Excited State Deactivation Paths in Heteroaraaromatics with Multiple Intermolecular Hydrogen Bonds," Dobkowski, J.; Herbich, J.; Galievsky, V.; Thummel, R. P.; Wu, F.; Waluk, J. Ber Bunsenges. Phys. Chem. 1998, 102, 469.
"The Preparation and Study of Tautomers Derived from 2-(2'-Pyridyl)-Indole and Related Compounds," Wu, F.; Hardesty, J.; Thummel, R. P. J. Org. Chem. 1998, 63, 4055.
"Intermolecular Excited State Double Proton Transfer in Dipyridocarbazole:Alcohol Complexes," Herbich, J.; Dobkowski, J.; Thummel, R. P.; Hegde, V.; Waluk, J., J. Phys. Chem. A 1997, 101, 5839.