Poster Abstract

Winter 2012 Biomedical Seminar Series

Friday, January 13, 2012

Pyridine Derivatives as Ligands for Organometallic Assemblies with Potential as Solar Cell Components and Molecular Machines.

José Núñez
University of Texas at El Paso

Self-assembly of organic molecules with metal ions has been used extensively in the fields of molecular magnetism,1 in the development of solar cell components,2 and in the synthesis of molecular rotors.3 Specific to the fields of magnetism and solar cells, is the development of compounds capable of efficient electron transfer and stable radical formation.2,4,5 Efficient electron transfer in triphenylamines led us to design pyridine derivatives 1-5, Figure 1, as potential radical-carriers for the production of magnetic liquid crystals6 and electron transfer complexes as solar cell components.5 Attempts to prepare compounds with a dynamic unit capable of fast rotation in the solid state, 6 and 7, Figure 2, are also presented. Specifically, compounds that exhibit a “gearing” effect of the mobile units, which is of interest in the field of molecular machines. A goal in this field is the preparation of compounds that mimic the structure and function of macroscopic machinery, such as gears and compasses,3,7 and are expected to be useful in nanotechnological devices, such as dipolar ferroelectric materials. Figure 1. Target pyridine amines. R = Alkyl chains of various lengths (CnH2n+1).

Figure 2. Target molecular “gears.”



1) a) Kahn, O.; Martinez, C. “Spin-Transition Polymers from Molecular Materials Toward Memory Devices.” Science 1998, 279, 44-48. b) Miller, J. S.; Epstein, A. J. “Organic and Organometallic Molecular Magnetic Materials-Designer Magnets.” Angew. Chem. Int. Ed. Engl. 1994, 33, 385-415. 2) Balzani, V.; Campagna, S.; Denti, G.; Juris, A.; Serroni, S.; Venturi, M. “Designing Dendrimers Based on Transition-Metal Complexes. Light-Harvesting Properties and Predetermined Redox Patterns.” Acc. Chem. Res. 1998, 31, 26-34. 3) a) Khuong, T.-A. V.; Nuñez, J. E.; Godinez, C. E. Garcia-Garibay, M. A. “Crystalline Molecular Machines: A Quest Towards Solid-State Dynamics and Function.” Acc. Chem. Res. 2006, 39, 413-422. b) Shima, T.; Hampel, F.; Gladysz, J. A. “Molecular Gyroscopes: Fe(CO)3 and Fe(CO)2(NO)+ Rotators Encased in Three-Spoke Stators; Facile Assembly via Alkene Metathesis.” Angew. Chem. Int. Ed. 2004, 43, 5537-5540. c) Nawara, A. J.; Shima, T.; Hampel, F.; Gladysz, J. A. “Gyroscope-Like Molecules Consisting of PdX2/PtX2 Rotators Encased in Three-Spoke Stators: Synthesis via Alkene Metathesis and Facile Substitution and Demetallation Reactions.” J. Am. Chem. Soc. 2006, 128, 4962-4963. 4) a) Bushby, R. J.; McGill, D. R.; Ng, K. M.; Taylor, N. “Disjoint and Coextensive Diradical Diions.” J. Chem. Soc., Perkin Trans. 2 1997, 1405-1414. b) Rajca, A. “A Polyarylmethyl Quintet Tetraradical.” J. Am. Chem. Soc. 1990, 112, 5890-5892. c) Bushby, R. J.; Ng, K. M. “High-Spin Organic Polymers.” Chem. Commun. 1996, 659-660. d) Koga, N.; Karasawa, S. “Molecule-Based Magnets in Heterospin Systems.” Bull. Chem. Soc. Jpn. 2005, 78, 1384-1400. e) Koga, N.; Iwamura, H. “Heterospin Systems Consisting of Organic Free Radicals and magnetic Metal Ions by Self-Assembling Strategy. Diazodi(4-pyridyl)methane as Photo-Responsive Ligands for Metal-Carbene-Based Heterospin Magnets.” Mol. Cryst. Liq. Cryst. 1997, 415-424. 5) a) Thompson, B. C.; Frechet, J. M. J. "Polymer–Fullerene Composite Solar Cells." Angew. Chem. Int. Ed. 2008, 47, 58-77. b) Günes, S.; Neugebauer, H.; Sariciftci, N. S. "Conjugated Polymer-Based Organic Solar Cells." Chem. Rev. 2007, 107, 1324-1338. c) Kim, J. Y.; Kim, S. H.; Lee, H.-H.; Lee, K.; Ma, W.; Gong, X.; Heeger, A. J. "New Architecture for High-Efficiency Polymer Photovoltaic Cells Using Solution-Based Titanium Oxide as an Optical Spacer." Adv. Mater. 2006, 18, 572-576. 6) a) Binnemans, K.; Galyametdinov, Y. G.; Deun, R. V.; Bruce, D. W.; Collinson, S. R.; Polishchuk, A. P.; Bikchantaev, I.; Haase, W.; Prosvirin, A. V.; Tinchurina, L.; Litvinov, I.; Gubajdullin, A.; Rakhmatullin, A.; Uytterhoeven, K.; Meervelt, L. V. “Rare-Earth-Containing Magnetic Liquid Crystals.” J. Am. Chem. Soc. 2000, 122, 4335-4344. b) Hudson, S. A.; Maitlis, P. M. “Calamitic Metallomesogens: Metal-Containing Liquid Crystals with Rodlike Shapes.” Chem. Rev. 1993, 93, 861-885. 7) a) Nuñez, J. E.; Natarajan, A.; Khan, S. I.; Garcia-Garibay, M. A. “Synthesis of a Triply Bridged Molecular Gyroscope by a Directed Meridional Cyclization Strategy.” Org. Lett. 2007, 9, 3559-3561. b) Dominguez, Z.; Khuong, T.-A. V.; Sanrame, C. N.; Dang, H.; Nuñez, J. E.; Garcia-Garibay, M. A. “Molecular Compasses and Gyroscopes with Polar Rotors: Synthesis and Characterization of Crystalline Form.” J. Am. Chem. Soc. 2003, 125, 8827-8837. c) Commins, P.; Nuñez, J. E.; Garcia-Garibay, M. A. “Synthesis of Bridged Molecular Gyroscopes with Closed Topologies: Triple One-Pot Macrocyclization.” J. Org. Chem. 2011, 76, 8355-8363.

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