Synthesis and Characterization of Polyaniline Derivatives: Poly(2-alkoxyanilines) and Poly(2,5-dialkoxyanilines)

Abstract

A series of 2-alkoxyanilines and 2,5-dialkoxyanilines with alkyl chains containing n = 1, 2,4, and 6 carbon atoms have been electropolymerized in acidic conditions and characterized by several techniques. The corresponding neutral polymers were found to be soluble in chloroform and tetrahydrofuran. On the other hand, chronoamperometry experiments have shown that the presence of long alkoxy groups {n -4 and 6) decreases the rate of polymerization, giving materials with a lower degree of polymerization. Electrochemical and spectroscopic measurements have demonstrated that the electron-donating effects of the side chains are more significant for 2,5-dialkoxyanilines and for the corresponding polymers. Moreover, the presence of electron-donating substituents has allowed a better characterization of the charge carriers in fully oxidized polyanilines. Indeed, in agreement with electrochemical results, in situ ESR experiments displayed two signals with similar g values, related to the presence of radical cations formed during the leucoemeraldineemeraldine transition and the emeraldine-pemigraniline transition. However, these radical cations were found to be more localized, with respect to polyaniline. Fully oxidized poly-(2,5-dialkoxyanilines) were found to be partially protonated at pH between -0.5 and 3, by electrochemical quartz crystal microbalance (EQCM) analysis. On the other hand, in situ conductivity measurements suggested that protonated imines do not act as efficient charge carriers. Finally, conductivity of 0.1 S/cm were found for disubstituted materials with short alkoxy groups ( = 1 and 2), whereas a decrease of 3-5 orders of magnitude were observed for materials bearing longer alkoxy groups ( = 4 and 6).

Synthesis of Poly (2,5-dimethoxyaniline) and Electrochromic Properties

“…Previous studies revealed that introducing mono alkyl or alkoxy substituents on the ortho position of the phenyl ring resulted in an increase of solubility, and at the same time, a decrease in conductivity [20][21][22][23][24][25] . However, the presence of 2,5-dialkoxy substituted on the phenyl rings resulted in an enhanced conductivity 12 . Recently, 2,5-dimethoxyaniline (DMA) has been reported to produce soluble poly(2,5-dimethoxyaniline) (PDMA) with a conductivity similar to polyamine [26][27][28][29][30][31][32][33] .…”

“…Therefore, the use of organic materials, particularly conducting polymers, has received more attention because of their fast response, low cost, good processibility, and color tailor ability 9 . Polyaniline, discovered in 1982 by Letheby 10 , is one of the most studied conducting polymers and has been used in many applications due to their environmental stability, low cost of fabrication, and unusual electrical and optical properties [11][12][13][14][15] . In addition, polyaniline exhibits electrochromic effects, from pale yellow to green to blue-velvet [16][17][18] .…”

Organocopper Compounds: From Elusive to Isolable Species, from Early Supramolecular Chemistry with RCuI Building Blocks to Mononuclear R2–nCuII and R3–mCuIII Compounds. A Personal View

“…Note that the N−Li coordination in 4 renders the C ipso centers in the LiR N Cu unit stereogenic (either S or R configuration). 37,49,76 This affects the assembly process, providing an enantiomeric pair of one diastereoisomer, either SSSS or RRRR; the presence of the Me 2 NCH 2 renders the assembly process stereoselective ( 13 C and 7 Li NMR and cryoscopy measurements). The use of a chiral (either S or R configuration) o-Me 2 NCHMe grouping makes the LiR N Cu unit diastereoisomeric.…”

“…The use of Ph-NCN allowed for the synthesis of the corresponding (rare at the time) organo-Ni(III) compounds. These NCNpincer-d 7 (18). 81 Finally, the stable organocopper(II) and -(III) compounds are the direct result of a selective C−H activation process starting from the corresponding arene compound interacting with the appropriate copper salt.…”

Understanding the Heteroatom Effect on the Ullmann Copper-Catalyzed Cross-Coupling of X-Arylation (X = NH, O, S) Mechanism

“…The use of bidentate ligands like phenanthroline [14][15][16][17][18], diamines [19][20][21], amino acids [22][23][24], and 1,3-diketones [25,26] among others [27][28][29][30] has not only met the demands of reliability, mildness, and functional group tolerance but also interesting modern features such as orthogonal reactivity [26]. The applications so far known have been spread over a diverse range of areas from pharmaceutical [31] and natural products [32][33][34] to materials fields [35,36].…”