Related Experiment Video
Updated: May 19, 2026
06:44
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Quinaldine: accessing two crystalline polymorphs via the supercooled liquid
Robert Kahlau1, Tanja Gnutzmann, Franziska Emmerling
1Physikalisches Institut, Universität Bayreuth, Bayreuth 95440, Germany.
The Journal of Chemical Physics
|August 17, 2012
Summary
Quinaldine, a liquid at room temperature, exhibits two distinct crystalline phases upon heating from its glassy state. Dielectric spectroscopy and X-ray diffraction reveal phase transitions and structural differences in these quinoline derivatives.
Area of Science:
- Materials Science
- Physical Chemistry
- Solid State Physics
Background:
- Quinaldine (2-methyl quinoline) can be supercooled into a glassy state.
- Heating the glassy state reveals subsequent transitions into dielectrically active phases.
Purpose of the Study:
- To investigate the phase transitions and structural properties of quinaldine.
- To analyze the reorientational relaxations and kinetics of phase transitions using dielectric spectroscopy.
- To characterize the crystalline phases and their nature.
Main Methods:
- Dielectric spectroscopy for tracking relaxations and kinetics.
- X-ray diffraction analysis for structural characterization.
- Calorimetric measurements for phase transition analysis.
Main Results:
- Two distinct crystalline phases were identified in addition to the supercooled liquid.
- First-order, irreversible phase transitions were observed in the supercooled regime.
- The intermediate crystalline phase was found to be metastable.
- Similar behavior was observed for 3-methyl quinoline, suggesting polymorphism in quinoline derivatives.
Conclusions:
- Quinaldine exhibits complex phase behavior with two crystalline polymorphs.
- Dielectric spectroscopy is effective for studying relaxations and phase transition kinetics.
- Polymorphism is a common characteristic among quinoline derivatives.
More Related Videos
Related Concept Videos
01:10Recrystallization: Solid–Solution Equilibria
Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, it exploits physical properties only, specifically, the solubility differences between the desired compound and impurities, either at a single temperature or at different temperatures, and under other selected conditions. The solid-solution equilibrium (solubility equilibrium) of each component in the solution represents a binary phase...
01:25Crystal Growth: Principles of Crystallization
Crystallization is a phase transformation process in which crystals are precipitated from a supersaturated solution or formed from other sources. During crystallization, atoms or molecules arrange themselves into a well-defined, rigid crystal lattice to minimize energy.
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent – the...
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent – the...
02:39Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
01:21Polymer Classification: Crystallinity
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
01:03Sublimation
Sublimation is the direct transformation of a solid to a gaseous state. For instance, at standard pressure and room temperature, solid carbon dioxide sublimes to gaseous carbon dioxide. The phase diagram depicts the conditions required for sublimation. This process occurs at the solid-gas phase boundary and is not observed above the triple point of the substance. The reverse of sublimation is called deposition, where a gaseous substance condenses directly into a solid. Sublimation and...
02:33Phase Transitions: Sublimation and Deposition
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...