Theoretical spectroscopic signature of synephrine using DFT and the effect of hydrogen removal

ABSTRACT

The present work deals with the vibrational spectroscopic signature of the synephrine molecule and its radical in the gas phase. We have optimized synephrine and synephrine^- in the ground state. The optimization of the neutral and de-protonated synephrine has been performed at the B3LYP/6-31++G(d, p) level of theory. The comparison of vibrational frequencies of both the structures has also been made. Most of the vibrational frequencies are in good agreement with the experimental ones. The effect of hydrogen removal from the site of oxygen atom upon geometrical parameters and vibrational frequencies of synephrine has been reported. Subsequently, the different thermodynamical parameters calculated at room temperature for the synephrine and its radical have been discussed. Interestingly, the enthalpy of formation for the synephrine and deprotonated synephrine has been calculated. The NBO analysis has been performed to check the stability of the electronic structure of the radical form of the synephrine molecule. Also, the HOMO-LUMO energy gap infers that synephrine is more reactive in its radical form.

KEYWORDS:

• DFT
• IR
• Raman
• synephrine
• NBO
• NCA

Acknowledgement

The author T. Yadav is grateful to UGC India for providing financial assistance in the form of UGC-DSKPDF (Award Number: No.F.4-2/2006 (BSR)/PH/19-20/0069). A. Pathak acknowledges SERB-DST (EMR/2016/005266 dated 27/09/2017) and IOE incentive grant BHU (incentive/2021-22/32439) for the financial support and IUCAA, Pune for associateship. Anil Kumar Vishwakarma is thankful to UGC for Junior Research Fellowship (Award Number:1499/ CSIR-UGC NET DEC.2018).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by UGC-DSKPDF: [grant number No.F.4-2/2006 (BSR)/PH/19-20/0069]; Science and Engineering Research Board: [grant number 2016/005266 dated 27/09/2017].