# Spectroscopic investigation (FTIR spectrum), NBO, HOMO-LUMO energies, NLO and thermodynamic properties of 8-Methyl-N-vanillyl-6-nonenamideby DFT methods.
> カプサイシン（8-メチル-N-バニリル-6-ノネンアミド）のDFT法によるFTIRスペクトル、NBO、HOMO-LUMOエネルギー、NLOおよび熱力学的特性の解析


## Abstract

A computational and spectroscopic characterization of capsaicin (8-methyl-N-vanillyl-6-nonenamide) was performed using DFT at the B3LYP/6-311++G(d,p) level. Solid-phase FTIR spectra recorded over 4000–400 cm⁻¹ were compared with theoretically derived vibrational frequencies; scaled harmonic values showed close agreement with experimental data. Natural bond orbital (NBO) analysis revealed intramolecular charge transfer (ICT) through electron density in σ* and π* antibonding orbitals, supported by second-order delocalization energies E(2). Hyperconjugative interactions and weak intramolecular hydrogen-bond-like contacts were identified as contributors to molecular stability. Dipole moment, polarizability, and hyperpolarizability were computed to assess nonlinear optical (NLO) potential. Temperature-dependent thermodynamic parameters—heat capacity, entropy, and enthalpy—were also derived. This study does not involve molecular hydrogen (H2) research.

## Bibliographic

- **Authors**: Leela JS, Hemamalini R, Muthu S, Al-Saadi AA
- **Journal**: Spectrochim Acta A Mol Biomol Spectrosc
- **Year**: 2015 (2015-07-05)
- **PMID**: [25813174](https://pubmed.ncbi.nlm.nih.gov/25813174/)
- **DOI**: [10.1016/j.saa.2015.03.027](https://doi.org/10.1016/j.saa.2015.03.027)
- **Study type**: other
- **Delivery route**: not specified
- **Effect reported**: not assessed

## Delivery context

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 25813174. https://h2-papers.org/en/papers/25813174
> **Source**: PubMed PMID [25813174](https://pubmed.ncbi.nlm.nih.gov/25813174/)