Structure, phase transitions and conductivity of 4-benzyl pyridinium dihydrogenmonosulfate C₆H₅CH₂C₅H₄NH⁺.

Abstract

The salt C₆H₅CH₂C₅H₄NH⁺. is monoclinic P2₁/a with the following unit cell dimensions a = 8.990(6) Å; b = 9.925(7) Å; c = 14.081(9) Å; β = 105.18(8)°; D _m = 1.491 mg m⁻³; D _x = 1.464 mg m⁻³; μ = 0.273 mm⁻¹; F(000) = 564; T = 298 K; R = 0.0512 and R _w = 0.1434 for 2150 independent reflections. The structure consists of infinite parallel two-dimensional planes built of anions and C₆H₅CH₂C₅H₄NH⁺ cations mutually connected by strong O–H · O and N–H · O hydrogen bonding. There are no contacts other than normal van der Waals interactions between the layers. In order to detect phase transitions and watch changes in the conductivity behaviour, investigations by differential scanning calorimetry (DSC) and electrical conductivity measurements were carried out. A dynamic order–disorder transition at 346 K was found. A super-ionic conductor state at ambient and high temperature is related to the proton jumping.

Keywords:

• Structure
• Phase transitions
• Conductivity measurements