Synthesis of nonsymmetrically N,N `-diaryi-substituted 4,4 `-bipyridinium salts with redox-tunable and titanium dioxide (TiO2)-anchoring properties

Autor(en): Bongard, D
Moller, M
Rao, SN
Corr, D
Walder, L 
Stichwörter: Chemistry; Chemistry, Multidisciplinary; ELECTROCHROMISM; FERROCYANIDE; FREE-RADICALS; PHOTOCHROMISM; SYSTEM; THIN-FILM ELECTRODES
Erscheinungsdatum: 2005
Herausgeber: WILEY-V C H VERLAG GMBH
Journal: HELVETICA CHIMICA ACTA
Volumen: 88
Ausgabe: 12
Startseite: 3200
Seitenende: 3209
Zusammenfassung: 
A general method for the synthesis of so far unknown nonsymmetrically substituted N-aryl-N'-aryl'-4,4'bipyridinium salts is presented (Scheme 1). The common intermediate in all procedures is N-(2,4-dinitrophenyl)-4,4'-bipyridinium hexafluorophosphate (1 - PF6-) For the synthesis of nonsymmetric arylviologens, 6 1(.)PF(6)(-) was arenamine-exchanged by the Zincke reaction, and then activated at the second bipyridine N-atom with 2,4-dinitrophenyl 4-methylbenzenesulfonate. The detailed preparation of the six N-aryl-N'-aryl'-viologens 21 -26 is discussed (Scheme 2). The generality of the procedure is further exemplified by the synthesis of two nonsymmetrically substituted N-aryl-N'-benzyl- (see 11 and 12), and seven N-aryl-N'-alkyl-4,4'-bipyridinium salts (see 28-34) including substituents with metal oxide anchoring and redox tuning properties. The need for these compounds and their usage as electrochromic materials, in dendrimer synthesis, in molecular electronics, and in tunable-redox mediators is briefly discussed. The latter adjustable property is demonstrated by the reduction potential measured by cyclic voltammetry on selected compounds (Table).
ISSN: 0018019X
DOI: 10.1002/hlca.200590257

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