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RESEARCH PRODUCT

Structure and properties of 2-cyanopyridinium perchlorate [2-CNPyH][ClO4]

Wojciech MedyckiRyszard JakubasJacek ZaleskiO. CzupińskiM. Wojtas

subject

Phase transitionChemistryDielectricCrystal structureCondensed Matter PhysicsCrystalPerchloratechemistry.chemical_compoundCrystallographyNuclear magnetic resonancePhase (matter)General Materials ScienceOrthorhombic crystal systemMonoclinic crystal system

description

The crystal structure of 2-cyanopyridinium perchlorate, [2-CNPyH][ClO4], has been determined at 100 (phase II) and 293 K (phase I). It is monoclinic P 21 at 100 K and orthorhombic P 212121 at 293 K. The dynamic properties of the crystal were studied by differential scanning calorimetry, dilatometry, pyroelectric, dielectric, proton (1H NMR), chlorine (35Cl NMR) magnetic resonance spectroscopies and the infrared method. The crystal undergoes a structural phase transition () at 170 K characterized by a complex mechanism involving both 'order–disorder' and 'displacive' contributions. It reveals pyroelectric properties below 170 K. The dielectric relaxation existing over phase I is due to the motion of the cyano group, whereas the dynamics of the [ClO4]− anions is reflected in the significant dielectric increment around the phase transition.

https://doi.org/10.1088/0953-8984/18/12/012