Measuring the Intrinsic Dipole Moments of Oligo-ortho-arylamides Stephen Bishop Riverside Community College Bioengineering Research Institute for Technical Excellence Advisor: Dr. Valentine I. Vullev Department of Bioengineering, University of California Riverside

Outline Background and Motivation Goals and Objectives Methods and Materials Results Conclusions Future Directions

Background and Motivation Photoinduced charge transfer in natural light-harvesting systems Photosynthetic reaction center (RC) 1. RC transmembrane proteins is α-helices spanning the electron-transfer pathways 2. The helix intrinsic dipoles generate the electric field that influence significantly on charge transfer. E. Rabinowitch, Annual Review of Plant Physiology, (1952) 3, Norbert Krau, et al., Nature Structural Biology, (1996) 3, 965 – 973

In 2005, the planet’s consumption rate was approximately 16TW The United States consumed approximately 3.4 TW The planet’s primary source of energy is fossil fuels (80%) Energy Information Administration, US Department of Energy. July Lewis, N.S.,Science 315, (2007). The practical energy generation rate approximates 600TW Image from oim.hq.nasa.gov Image from

Photoinduced charge transfer system --Donor-Bridge-Acceptor (DBA) conjugates Fedorova, A., et all. "Photoinduced electron-transfer along a-helical and coiled-coil," Journal of the American Chemical Society 125, (2003). The Biomimic system: Bridge molecules: polypeptide α-helices µ= 4-5 D per residue The Bioinspired system: Bridge molecules: bioinspired macromolecules µ= 3-5 D per residue depends on the polymers

Goals and Objectives Long-term goal: To improve the charge-transfer efficiency of photovoltaic devices in solar energy conversion. My project objectives: 1. Engineering design and synthesize macromolecular electrets 2. Investigate the electric properties of electrets

Methods and Materials 1. Engineering design macromolecular electrets

2. Investigate the electric properties of electrets Theoretical Calculation: Density functional theory (DFT) ab initio calculations Experimental Validation: Dielectric-constant measurements (impedance spectroscopy) Density measurements Frisch MJ, et al., Gaussian 03, Revision C.02;Wallingford, CT:Gaussian, Inc., 2004.

Experimental Validation: Breitung, Vaughan, and McMahon, Rev. Sci. Instrum., (2000) 71,

Results 1. Engineering design of macromolecular electrets—aromatic oligo-ortho-arylmides n=1 Wet chemistry synthesis General organic chemistry Solid-phase synthesis Polypeptide synthesizer

Wet chemistry Synthesis—monomer Synthesis procedure DMAP, DMF Ice bath, Ar gas + Büchi Rotovapor R-114Separation flask

1 H-NMR Spectra: N2-hexanoylanthranylamide a a b b c c d d e e f f g h i j g h i j k k c

2. Investigate the electric properties of electrets – monomer & polymer Theoretical Calculation: Ashraf, M. K; Vullev, V. I. et al. Biotechnology Progres 2009, 25,

3. Investigate the electric properties of electrets (monomer) Experimental Validation (in progress)

Conclusions Oligoanthranilamides that have intrinsic dipole moments resultant from the orientation of their amide and hydrogen bonds were designed. The dipole moments of macromolecules were predicted by density functional theory (DFT) ab initio calculations. The monomer was synthesized with high yield and the dipole moment measure is in process.

Future Directions Finish the dipole moment measurement of monomer and validate the theoretical calculation. Synthesize polymers by solid-phase polypeptide synthesizer. Measure the dipole moments of polymers.

Acknowledgements Jun Wang Duoduo Bao Gokul Upadhyayula Robert Bonderer Noah Johnson Dr. Valentine I. Vullev Dr. Sharad Gupta Dr. Daniel Bernier (RCC) Dr. Diane Marsh (RCC)