Polyaniline Doping by α,α-Difluoro-β-amino Acids

Abstract

Currently, polyaniline (PANI) is considered as a promising polymer that can be used in biosensors, drug delivery systems, bioelectronics, etc. Its biocompatibility can be strongly improved by using dopants with biofunctionality. This study reveals the protonation/doping of PANI by fluorinated analogs of natural amino acids, namely, α,α-difluoro-β-amino acids (DFAAs) with alkyl and aromatic tails in N -methylpyrrolidone solutions. We find that these acids can dope PANI due to both the weakened basicity of their amino groups because of two fluorine atoms in α,α-positions and specific intermolecular interactions (π–π stacking, alkyl−π, F−π) of their tails with units of PANI chains. These interactions did not give the doped PANI salts with high conductivity but led to formation of stable PANI-DFAA complexes, which were confirmed both by clear changes in the UV–Vis and Fourier transform infrared spectra of the protonated/doped PANI and by their conductivity of ∼10 –6 S/cm. Our results suggest an applicability of such PANI complexes as carriers of DFAA for their biomedical applications.

Understanding of mechanistic perspective in sensing of energetic nitro compounds through spectroscopic and electrochemical studies

“…Figure 2 shows UV–Vis spectra of 100 ppm CSA(PANi) dissolved in DMF along with the addition of 10% of different HEMs individually. The absorption spectra show two distinct peaks at 303 and 550 nm corresponding to π → π* in the semiquinoid unit and n → π* transition of non‐bonding electron on nitrogen, respectively 20,24–29 . There is no shift in wavelength of the any of the absorption spectra.…”

“…π* transition of non-bonding electron on nitrogen, respectively. 20,[24][25][26][27][28][29] F I G U R E 1 CSA(PANi) and interaction high energy materials (HEMs) to CSA(PANi) [Color figure can be viewed at wileyonlinelibrary.com]…”

“…The polyaniline also shows fluorescence properties; however, it suffers from poor solubility and processability along with π stacking, which limits the applicability of polyaniline 14–17 . These drawbacks are overcome by proper functionalization (doping) of polyaniline with bulkier groups namely, camphor sulfonic acid (CSA), benzene sulfonic acid, and so forth 18–20 . In the present study, we employ CSA as a dopant since it is water‐soluble and the excess dopants can easily be washed away 14 .…”

“…[14][15][16][17] These drawbacks are overcome by proper functionalization (doping) of polyaniline with bulkier groups namely, camphor sulfonic acid (CSA), benzene sulfonic acid, and so forth. [18][19][20] In the present study, we employ CSA as a dopant since it is water-soluble and the excess dopants can easily be washed away. 14 Acid doping increases the conductivity of polyaniline and decreases the π-π stacking in the polyaniline chains.…”

Effect of Acid Doping on Junction Characteristics of ITO/Polyaniline/N719/Ag Diode

“…9 Several acids (both organic and inorganic) have been used as doping agents to enhance electrical conductivity of PANI, including hydrochloric acid (HCl), 10 acetic acid, 11 camphor sulfonic acid, 12 and even amino acid. 13 PANI is considered a p-type organic semiconductor because it has radical cation species (i.e. polarons), which serve as hole transport materials in electronic devices.…”