title: Strategies for electrooptic film fabrication. Influence of pyrrole-pyridine-based dibranched chromophore architecture on covalent self-assembly, thin-film microstructure, and nonlinear optical response.
abstract: The new dibranched, heterocyclic "push-pull" chromophores bis{1-(pyridin-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane (1), 1-(pyrid-4-yl)-2-(N-methyl-5-formylpyrrol-2-yl)ethylene (2), {1-(N-methylpyridinium-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}{(1-(pyridin-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane (3), N-methyl-2-[1-(N-methylpyrid-4-yl)ethen-2-yl]-5-[pyrid-4-yl]ethen-2-yl]pyrrole iodide (4), bis{1-(N-methyl-4-pyridinio)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane iodide (5), and N-methyl-2,5-[1-(N-methylpyrid-4-yl)ethen-2-yl]pyrrole iodide (6) have been synthesized and characterized. The neutral (1 and 2) and monomethyl salts (3 and 4) undergo chemisorptive reaction with iodobenzyl-functionalized surfaces to afford chromophore monolayers SA-1/SA-2 and SA-3/SA-4, respectively. Molecular structures and other physicochemical properties have been defined by (1)H NMR, optical spectroscopy, and XRD. Thin-film characterization by a variety of techniques (optical spectroscopy, specular X-ray reflectivity, atomic force microscopy, X-ray photoelectron spectroscopy, and angle-dependent polarized second harmonic generation) underscore the importance of the chromophore molecular architecture as well as film growth method on film microstructure and optical/electrooptic response.
authors.affiliation: Department of Chemistry, Department of Physics and Astronomy, and the Materials Research Center, Northwestern University, Evanston, IL 60208-3113, USA. a-facchetti@northwestern.edu
authors.forename: Antonio
authors.initials: A
authors.lastname: Facchetti
authors.forename: Luca
authors.initials: L
authors.lastname: Beverina
authors.forename: Milko E
authors.initials: ME
authors.lastname: van der Boom
authors.forename: Pulak
authors.initials: P
authors.lastname: Dutta
authors.forename: Guennadi
authors.initials: G
authors.lastname: Evmenenko
authors.forename: Atindra D
authors.initials: AD
authors.lastname: Shukla
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Stern
authors.forename: Giorgio A
authors.initials: GA
authors.lastname: Pagani
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks