# Unravelling the nature of intra-molecular hydrogen bonds in curcumin using in-situ low temperature spectroscopic studies.
> 低温分光法によるクルクミン分子内水素結合の性質解明


## Abstract

Curcumin possesses diverse biological activities including anticancer, antiviral, and anti-inflammatory properties, and also serves as a model system for investigating strong intramolecular OH----O hydrogen bonds that govern its physicochemical behavior. Systematic variable-temperature infrared spectroscopy was conducted over the 350–75 K range, with findings corroborated by Raman spectroscopy. The two intramolecular hydrogen bonds located at the molecular periphery, commonly assumed to be equivalent, were found to differ markedly in character. The central enol-group hydrogen bond, identified as the strongest, exhibited notable strengthening upon cooling. Subtle spectral shifts indicative of hydrogen-bond reorientation were detected near 210 K, yet no major structural phase transition occurred across the measured range. These findings are expected to aid in predicting reaction pathways during chemical complexation of curcumin.

### Mechanism

Intramolecular OH----O hydrogen bonds in curcumin strengthen upon cooling, with the central enol-group bond showing the most pronounced enhancement. The two peripheral hydrogen bonds, previously considered equivalent, were demonstrated to differ in nature.

## Bibliographic

- **Authors**: Bhatt H, Thomas S, Vishwakarma SR
- **Journal**: Spectrochim Acta A Mol Biomol Spectrosc
- **Year**: 2021 (2021-10-05)
- **PMID**: [33992891](https://pubmed.ncbi.nlm.nih.gov/33992891/)
- **DOI**: [10.1016/j.saa.2021.119903](https://doi.org/10.1016/j.saa.2021.119903)
- **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 33992891. https://h2-papers.org/en/papers/33992891
> **Source**: PubMed PMID [33992891](https://pubmed.ncbi.nlm.nih.gov/33992891/)