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M. Ilic, E. Koglin, A. Pohlmeier, H. D. Narres, M. J. Schwuger

Adsorption and Polymerization of Aniline on Cu(II)-Montmorillonite:  Vibrational Spectroscopy and ab Initio Calculation

Langmuir

American Chemical Society (ACS)

2000

Batch adsorption experiments in the presence of oxygen were performed to study the interlayer reactions of aniline on Cu(II)-montmorillonite in aqueous solutions. At concentrations below a critical value of CC ) 2.6 mmol dm-3 only a colored Cu(II)-aniline complex is formed, characterized by a stability constant of log(Kassoc/dm3 mol-1) ) 1.5. At concentrations beyond Cc aniline polymerizes yielding a dark brown product, which is identified by two vibrational spectroscopy techniques, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and FT-Raman spectroscopy. Vibrational assignment of aniline, polyaniline, and the interlayer reaction products of aniline at Cu(II)-montmorillonite was achieved by a comparison of the band position and intensity observed in the ATR and FT-Raman spectra with wavenumbers and intensities (IR and Raman) from ab initio quantum-mechanical calculations. Density functional theory (DFT, B3LYP/6-31G*) has been used to calculate the geometry, frequencies, and intensities (IR and Raman) of aniline. The geometry and vibrational calculations of a four-ring unit (emeraldine base, EB) are believed to be a good representation of the polyaniline at Cu(II)-montmorillonite. The geometry of EB was fully optimized at the Hartree-Fock level of theory. The data of polyaniline presented suggest that IR and Raman data calculated ab initio on relatively short oligomers (quantum-mechanical oligomer approach) may provide valuable information regarding the interpretation of vibrational spectra of polymers. From the comparison of experiments and calculations, it is concluded that a catalytic/intercalation polymerization of aniline to polyaniline took place inside the interlayer of the Cu(II)-montmorillonite clay mineral.

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23

8946

8951

10.1021/la000534d

0743-7463

Анилин, адсорпција, полимеризација, Cu(II)-Монтморилонит, ФТИР, аб инитио прорачун

Aniline, adsorption, polymerization, Cu(II)-Montmorillonite, FTIR, ab Initio Calculation

https://pubs.acs.org/doi/pdf/10.1021/la000534d

M20

М21

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