Azinium-(π-bridge)-pyrrole NLO-phores: Influence of heterocycle acceptors on chromophoric and self-assembled thin-film properties

Antonio Facchetti*, Alessandro Abbotto, Luca Beverina, Milko E. van der Boom, Pulak Dutta, Guennadi Evmenenko, Tobin J. Marks, Giorgo A. Pagani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

Novel heterocycle-based azine/azinium-(π-bridge)-pyrrole systems, [(1-(pyrid-4-yl)-2-(N-methylpyrrol-2-yl)]ethene (1), 5-[(N-methylpyrrol-2-yl)azo]quinoline (2), 5-[(N-methylpyrrol-2-yl)azo] isoquinoline (3), and the corresponding N-methotriflates 4-6 were synthesized and characterized. Chromophore precursors 1-3 react with iodobenzyl-functionalized surfaces (10) affording polar-ordered σ-bonded thin films 7-9, respectively. All systems were studied by optical (UV-visible, photoluminescence) spectroscopies, electrochemical (CV), and thermal (TGA, DSC) techniques. Self-assembled chromophore monolayers 7-9 on glass, quartz, and silicon substrates have been characterized by a full complement of physicochemical techniques: optical spectroscopy, aqueous advancing contact angle measurements, specular X-ray reflectivity, atomic force microscopy, and angle-dependent polarized second harmonic generation. Film second harmonic generation responses χ(2)zzz vary more than 1 order of magnitude ranging from 1.3 and 1.6, to 34 × 10-8 esu for 9-, 8-, and 7-based monolayers, respectively. This study demonstrates the following: (i) SA monolayers can be prepared using various types of azine-containing precursors; (ii) chromophore and SA film properties are influenced predominantly by the nature of the π-deficient azinium acceptor; (iii) unsubstituted, π-excessive pyrrol-2-yl rings can act as primary donor groups in push-pull conjugated systems.

Original languageEnglish (US)
Pages (from-to)4996-5005
Number of pages10
JournalChemistry of Materials
Volume14
Issue number12
DOIs
StatePublished - Dec 1 2002

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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