Molecular modelling and vibrational investigations of ammonium-based ionic liquid (CLTOAB)

Abstract

CLTOAB is an ammonium-based ionic liquid composed of ε-Caprolactam (CL) C₆H₁₁NO and tetraoctylammonium bromide (TOAB) (C₃₂H₆₈BrN). In this study, experimental IR and Raman spectra of CLTOAB ionic liquid together with the computational results of the compound have been reported. The optimized geometry, vibrational frequencies, IR intensities and Raman activities of the CLTOAB were calculated using the wb97xd and B3LYP density functional methods combined with the 6-31G(d,p) basis set using Gaussian 03 program. The complete assignment of the bands was performed based on the potential energy distributions (PED%). The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The Gauge-including atomic orbital ¹H-NMR and ¹³C-NMR chemical shifts calculations were carried out and compared with the experimental data. Furthermore to evaluate interaction between CLTOAB and DNA, molecular docking study was carried out.

Communicated by Ramaswamy H. Sarma

Keywords:

• ammonium-based ILs
• CLTOAB
• DFT calculations
• vibrational analysis

Acknowledgements

We thank Professor Tom Sundius (University of Helsinki) for his valuable comments on PED results, and thank Associate Professor Ali Durmus (Istanbul University - Cerrahpasa) for the interpretation of the DSC thermograph.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Research funds of Istanbul University [ÖNAP-2423, N-3341, N-3875, BEK-2017-26282, and BEK-2017-26190].