Steric effects on the optical and electrochemical properties of N-substituted pyrrole–thiophene monomers and polymers

Abstract

Monomers consisting of N-alkyl-su bstituted-2,5-bis(2-thienyl)pyrroles and their electro-oxidatively generated polymers display electrochemical and optical properties which reflect the steric demands of the alkyl substituents.-

An electrochromic and fluorescent polymer based on 1-(1-naphthyl)-2,5-di-2-thienyl-1H-pyrrole

“…In addition, the disappearence of the band at 3098 cm À1 (for a-hydrogens of thiophene rings) confirms the coupling at a-position of the thiophene rings [29]. Therefore, the corresponding polymer film has linear chains due to the proceeding polymerization via a-a linkages.…”

Processable electrochromic and fluorescent polymers based on N-substituted thienylpyrrole

“…For example, Ferraris et al obtained soluble and conducting polymers via either electrochemical or chemical oxidation of ␣-linked thienylpyrrole ring systems with alkyl substituents on the ␤-position of the central pyrrole ring [9]. The following studies of Ferraris et al and Toppare et al mainly focused on the elucidation of both electrochemical and optical properties of N-substituted polythienylpyrroles [10][11][12][13][14][15][16][17][18][19].…”

N-substituted 2,5-di(2-thienyl)pyrroles: application, production, properties, and electrochemical polymerization (review)

“…The films produced as a result of polymerization had conductivity of 3.3 S/cm (in the case of doping with bisulfate anions) [18,20]. A promising direction in the development of conducting organic polymers is the synthesis and study of the substituted and unsubstituted triheterocycle 2 [21][22][23]. Some of the interesting characteristics exhibited by these compounds are their nonlinear optical characteristics; in [24] a comparison was made of the optical behavior of such compounds with the characteristics of compounds of similar structure.…”

“…The conductivity of the polymers produced by electropolymerization, containing N-octyl-and N-hexyl substituents and unsubstituted at position 3, amounted to 10 S/cm [23]. During investigation of the steric effect of the substituents (Me, Et, i-Pr, heptyl, octyl) at the nitrogen atom on the optical and electrochemical characteristics of the obtained copoly(thienylpyrroles) it was established that the structure of the trimer departs from planar as the steric hindrances created by these groups increases [21][22][23]. This is reflected in the values of the oxidation potentials of the monomers and the absorption minima of both the initial monomers and the obtained polymers (Table 1).…”