Faculty

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Russell Schmehl, Professor                                   
Ph.D., 1980, North Carolina
Office: 5059 Percival Stern Building
Telephone: (504) 862-3566
Email: russ@tulane.edu

Discipline:                                           
Photochemistry, Materials, Transition Metal Chemistry

Areas of current interest include:

Light Harvesting
Chemists can play a significant role in the search for new sources of renewable energy to help meet future world energy needs. Of all the prospective renewable energy sources, solar offers the greatest potential return (as much as ten times the world energy needs expected at the end of this century). One area of solar energy related research for chemists is the study of photochemical reactions of molecules that absorb visible light.

Our research includes considerable organic and inorganic synthesis.  Our recent efforts have focused on preparing clusters of visible light absorbing chromophores that may be used to "harvest" light. Such light harvesting arrays can be used to channel energy into electrochemical cells designed to convert light to electrical energy (photoelectrochemical cells). The types of chromophores we have examined include porphyrins , phthalocyanines and a variety of transition metal complexes. Through a combination of synthetic and laser spectroscopic investigations, our group studies the factors that influence the reactivity and stability of these classes of visible chromophores.

Photocatalysts

Another area of research in our group, related to solar energy conversion to chemical energy, is the study of what is referred to as one photon-two electron reactions. Using transition metal complexes that undergo two electron redox processes (i.e. Pt(II) to Pt(IV)), we are attempting to develop photochemical systems that can undergo redox cycling to serve as photocatalysts for the production of useful reagents.

Materials

Many of the N-heterocyclic ligands we prepare for light harvesting systems are strongly luminescent and are related to materials used for the development of organic light emitting diodes (OLEDs). The ligands have emission that can be tuned to span the visible spectrum. 

We are currently exploring the luminescence behavior of these complexes in solution and on surfaces.  By gaining control of surface morphology via various surface deposition techniques, we hope to prepare highly luminescent surface bound chromophores that can be used in OLEDs or sensing applications.  We study surface marpology using scanning electron microscopy (SEM) and (TEM).

Selected Publications

Akatsuka, Kosho; Ebina, Yasuo; Muramatsu, Masaru; Sato, Toshiyuki; Hester, Heidi; Kumaresan, Duraisamy; Schmehl, Russell H.; Sasaki, Takayoshi; Haga, Masa-Aki. Photoelectrochemical Properties of Alternating Multilayer Films Composed of Titania Nanosheets and Zn Porphyrin. Langmuir (2007), 23(12), 6730-6736

Vaidya, Srivathsa; Johnson, Claire; Wang, Xian-Yong; Schmehl, Russell H.. Fluorescence solvato and vapochromism of a dimethylaminostyryl terpyridine derivative. Journal of Photochemistry and Photobiology, A: Chemistry (2007), 187(2-3), 258-262

Wang, Xian-Yong; Del Guerzo, Andre; Tunuguntla, Hari; Schmehl, Russell H.. Photophysical behavior of Ru(II) and Os(II) terpyridyl phenylene vinylene complexes: perturbation of MLCT state by intra-ligand charge-transfer state. Research on Chemical Intermediates (2007), 33(1-2), 63-77

Rupesh Narayana-Prabhu and Russell H. Schmehl, “Photoinduced Electron Transfer Reactions of Pt(II) Terpyridyl Acetylide Complexes: Reductive Quenching in a Hydrogen Generating System”, Inorg. Chem., 2006, 45, 4319-21.

Mauricio Cattaneo, Florencia Fagalde , Néstor E. Katz, Ana María Leiva, Bárbara Loeb and Russell Schmehl, “Enhancement of Metal-to-Metal Coupling at a Considerable Distance by Using 4-pyridinealdazine as a Bridging Ligand in Polynuclear Complexes of Rhenium and Ruthenium”,  Inorg. Chem., 2006, 45, 127-136. 

Xian-yong Wang, Andre del Guerzo, Sujoy Baitalik, Gerald Simon and Russell Schmehl “The Influence of Bridging Ligand Electronic Structure on the Photophysical Properties of Noble Metal Diimine and Triimine Light Harvesting Systems”,  Photosynthesis Research, 2006,  87, 83-103. (invited review)

Soma Chakraborty, Thaddeus J. Wadas, Heidi Hester, Russell Schmehl and Richard Eisenberg, “Platinum Chromophore Based Systems for Photoinduced Charge Separation: A Molecular Design Approach for Artificial Photosynthesis” ,   Inorg. Chem. , 2005,  44, 6865-6878.

Sujoy Baitalik, Xian-yong Wang and Russell H. Schmehl “A Trimetallic Mixed Ru(II)/Fe(II) Terpyridyl Complex With A Long-Lived Excited State In Solution At Room Temperature”, J. Amer. Chem. Soc., 2004, 126, 16304-16305.

Xian-yong Wang, Andre DelGuerzo and Russell H. Schmehl “Photophysical Behavior of Transition Metal Complexes Having Interacting Ligand Localized and Metal-to-Ligand Charge Transfer States” J. Photochem. Photobiol., C: Reviews, 2004, 5(1), 55-77. (invited review)

Gerald A. Simon and Russell H. Schmehl "Emission of Coordination Compounds" in "Comprehensive Coordination Chemistry II", volume I, B. Lever, ed., Elsevier : New York, 2003, pp 315-25.

Xian-yong Wang, Andrew DelGuerzo and Russell H. Schmehl "Preferential Solvation of an ILCT Excite State in Bis-(terpyridine-phenylenevinylene)Zn(II) Complexes", J. Chem. Soc., Chem. Comm., 2002, 2344-5.

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