Student Project Abstracts 2005 - Pluto - University of Washington

SYNTHESIS OF DENDRON-FUNCTIONALIZED CHROMOPHORES: AN APPROACH TO UPRAMOLECULAR ASSEMBLY FOR ELECTRO-OPTIC APPLICATIONSTherefore, a monolithic anthracene-based dendron was synthesizedand covalently attached to a chromophore. It was hypothesizedthat replacement of a phenyl group with an anthracenylgroup would lead to an increased cohesive energy betweenthe dendrons (An-Ar F ) thereby strengthening the self-aligningproperties of the chromophore. Furthermore, it was expected thatthe increase in noncovalent attraction between dendrons wouldresult in a higher T gand an increased thermal stability upon electricfield poling.While previous work has only been concerned with monolithicdendrons, it is important to inquire about the nature of binarydendron systems. The potential for noncovalent, electrostaticquadrupole-quadrupole interactions between dendrons stillexists, but it is unclear whether the binary dendron systems offerany energetic or geometric advantages for supramolecular assembly.With this uncertainty present binary dendrons were alsosynthesized with arene/fluoroarene moieties.EXPERIMENTALSynthesis of Dendron-Functionalized ChromophoresThe reaction scheme above illustrates an important syntheticsimplification of the binary dendron systems (dendrons 1 and 2)relative to the monolithic dendron systems (dendrons 3 and 4).λMaterial a T g( o C) b λ maxin soln. (nm) c maxin thinfilm (nm)Poling Field (MV/cm) r 33(pm/V) d1 57 671 719 0.75 522 76 655 689 0.75 513 75 667 703 1 1084 153 678 771 --- ---I. 122 670 720 0.75 95II. 76 660 700 0.73 102III. 122 670 720 0.75 51a. Materials 1-4 synthesized previously by Jen Groupb. Measured by DSC (10 o C/min in N 2)c. Solution in 1,4-dioxaned. E-O coefficient measured by simple reflection at the wavelength of 1300 nmTable 2. Results and Comparisons68 CMDITR Review of Undergraduate Research Vol. 2 No. 1 Summer 2005