The two major polymorphs of the active pharmaceutical ingredient indomethacin were studied using a combination experimental low-frequency vibrational spectroscopies, theoretical solid-state density functional theory, and ab initio molecular dynamics calculations. results enable complete spectral assignment IR Raman spectra, yield new insight into energetic dynamical factors present within solids to be understood. Ultimately, these are used rationalize thermodynamic properties crystals, which...

A single lattice vibration at 15.5 cm⁻¹ serves as a gateway for the polymorphic conversion of thermosalient 1,2,4,5-tetrabromobenzene crystals.

In ZIF-8 and its cobalt analogue ZIF-67, the imidazolate methyl-groups, which point directly into void space, have been shown to freely rotate - even down cryogenic temperatures. Using a combination of experimental terahertz time-domain spectroscopy, low-frequency Raman state-of-the-art ab initio simulations, methyl-rotor dynamics in ZIF-67 are fully characterized within context quantum-mechanical hindered-rotor model. The results lend insight fundamental origins experimentally observed...

Cis–trans isomerization of muconic acid is an important component various chemical syntheses. Despite the existence three geometric isomers, little atomically precise information actually known their structures. In this work, complete crystal structures cis–cis, cis–trans, and trans–trans were determined via single-crystal X-ray diffraction then further analyzed using terahertz vibrational spectroscopy solid-state density functional theory. addition to being first reported structure for...

Through a combined experimental and theoretical investigation we determine that the fundamental modes of three quinacridones fall in terahertz spectral range (1–10 THz, ∼30–300 cm–1). In each spectrum resonances correspond to wagging, rocking, or twisting quinacridone rings, with most intense absorption being an in-plane rocking vibration carbonyl oxygens. spite these similarities, demonstrate measurements readily differentiate β-quinacridone, γ-quinacridone, 2,9-dimethylquinacridone. The...

While theophylline has been extensively studied with multiple polymorphs discovered, there is still currently no conclusive structure for the metastable form III. In this present work, by combining more widely used techniques such as X-ray diffraction and thermogravimetric analysis emerging like low-frequency Raman terahertz time-domain spectroscopy, to analyze dynamics of a crystalline system, it was possible provide further evidence that III monohydrate water molecules removed. Solid-state...

Quinacridone and its substituted analogs are pigments widely used in art industry. The temperature dependence of the crystal structures two quinacridone polymorphs (β γ), along with common variant 2,9-dimethylquinacridone, were investigated using powder X-ray diffraction terahertz spectroscopy. These then compared solid-state density functional theory simulations both vibrations. patterns collected at eight temperatures range 13-298 K spectra fifteen 20-300 K. Simulations absolute zero...

The two major polymorphs of the active pharmaceutical ingredient indomethacin were studied using a combination experimental low-frequency vibrational spectroscopies, theoretical solid-state density functional theory and \textit{ab initio} molecular dynamics calculations. results enable complete spectral assignment IR Raman spectra, yield new insight into energetic dynamical factors present within solids to be understood. Ultimately, these are used rationalize thermodynamic properties...

Muconic acid is known to exhibit three isomeric forms, but the cis-trans isomer largely uncharacterized. Using a combination of X-ray diffraction, solid-state density functional theory, and terahertz spectroscopy, detailed structural investigation was performed for muconic acid. Two crystalline polymorphs were discovered during this study through their distinct spectra. Terahertz data also revealed hydrate species present in bulk samples that related relative stabilities two polymorphs....

<div>Understanding the nature of interatomic interactions present within pores metal-organic frameworks</div><div>is critical in order to design and utilize advanced materials</div><div>with desirable applications. In ZIF-8 its cobalt analogue</div><div>ZIF-67, imidazolate methyl-groups, which point directly</div><div>into void space, have been shown freely rotate - even</div><div>down cryogenic temperatures. Using a...

Understanding the nature of interatomic interactions present within pores metal-organic frameworksis critical in order to design and utilize advanced materialswith desirable applications. In ZIF-8 its cobalt analogueZIF-67, imidazolate methyl-groups, which point directlyinto void space, have been shown freely rotate - evendown cryogenic temperatures. Using a combination ex-perimental terahertz time-domain spectroscopy, low-frequencyRaman state-of-the-art ab initio simulations,the...

<pre>The two major polymorphs of the active pharmaceutical ingredient indomethacin were studied using a combination experimental low-frequency vibrational spectroscopies, theoretical solid-state density functional theory and \textit{ab initio} molecular dynamics calculations. The results enable complete spectral assignment IR Raman spectra, yield new insight into energetic dynamical factors present within solids to be understood. Ultimately, these are used rationalize thermodynamic...

In this study Terahertz (THz) spectra of several commonly used active pharmaceutical ingredients are reported. Results showed that all the API's had unique bands associated with structures allowing to analyse both qualitatively and quantitatively. The liq. nitrogen temperature solid state gas phase theoretical analysis meloxicam have also been carried out. addition, transparency drug packaging materials like plastic blisters, cartons were checked see technique's ability for in situ...

While drugs are typically created, stored, and administered in the more stable crystalline state, there is interest industrial settings to stabilize amorphous pharmaceuticals overcome bioavailability constraints. The stability of an pharmaceutical directly tied its β-glass transition, although detection often difficult. Terahertz time-domain spectroscopy (THz-TDS) one technique that can be used determine this transition as well commonly observed α-glass same experiment. both transitions...