# Terahertz and Raman Spectroscopic Investigation of Monohydrate Cocrystal of Antitubercular Isoniazid with Protocatechuic Acid.
> 抗結核薬イソニアジドとプロトカテク酸の一水和物共結晶のテラヘルツおよびラマン分光学的解析


## Abstract

A monohydrate cocrystal composed of isoniazid (INH) and protocatechuic acid (PA) in a 1:1 molar ratio was prepared via solvent evaporation. Terahertz time-domain spectroscopy (THz-TDS) and Raman spectroscopy were employed to characterize the resulting solid form alongside the parent compounds. Distinct spectral differences between the cocrystal and its individual components were identified in both THz absorption and Raman vibrational profiles. Density functional theory (DFT) calculations were performed to optimize the cocrystal geometry and assign vibrational modes. The combined approach provided molecular-level insight into intra- and intermolecular hydrogen bond interactions within the cocrystal lattice, demonstrating a useful analytical strategy for characterizing pharmaceutical cocrystal formation.

### Mechanism

Intra- and intermolecular hydrogen bonding between INH and PA stabilizes the cocrystal lattice; DFT calculations were used to assign corresponding vibrational modes and optimize the molecular geometry.

## Bibliographic

- **Authors**: Bo Y, Fang J, Zhang Z, Xue J, Liu J, Hong Z, et al.
- **Journal**: Pharmaceutics
- **Year**: 2021 (2021-08-20)
- **PMID**: [34452267](https://pubmed.ncbi.nlm.nih.gov/34452267/)
- **DOI**: [10.3390/pharmaceutics13081303](https://doi.org/10.3390/pharmaceutics13081303)
- **PMC**: [PMC8400006](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8400006/)
- **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 34452267. https://h2-papers.org/en/papers/34452267
> **Source**: PubMed PMID [34452267](https://pubmed.ncbi.nlm.nih.gov/34452267/)