Use of the pyroelectric effect to determine the absolute orientation of the polar axis in molecular crystals

Abstract

Daniels, Glen Cunkle, and Ferdinand Salvajion for their experimental contributions and Professors Leon Stock, Peter Beak, and Victor Snieckus for stimulating discussions. G.C. thanks Zambon Chimica s.p.a. for a leave of absence.

Analysis of the Polarization Distribution in a Polar Perhydrotriphenylene Inclusion Compound by Scanning Pyroelectric Microscopy

“…A much simpler technique using charged powder particles was previously applied to organic crystals. 9 In our case the use of Pb 3 O 4 and sulfur powders led to a polarity assignment in agreement with SPEM.…”

Structure of N-iodosuccinimide

“…A single crystal of N-iodosuccinimide was heated on a microscope slide to N353 K for 5-10 min. The slide was removed from the hot stage, and after 3-5 s sprayed with a mixture of yellow flowers of sulfur, carmine and lycopodium powder dyed with methyl violet as described earlier (Patil, Curtin & Paul, 1985).…”

“…The polar axis in the crystal of N-iodosuccinimide is the crystallographic c axis. Application of the Kundt-Biirker test (Patil, Curtin, & Paul, 1985) to crystals of N-iodosuccinimide with the morphology shown in Fig. 3 indicated that, on heating, the blunt end of the crystal became redyellow (developed positive charge) and the sharp end blue (developed negative charge).1" It has been found in several other cases (Pennington et al, 1988, and references therein;Padmanabhan, Paul & Curtin, in preparation), that the direction of the electric dipole developed on heating the crystal (pyroelectric effect) is the same as the direction of polarization of the crystal resulting from the orientation of its internal structure.…”

Crystal structure and direction of the polar axis of (–)-(1S)-pinonic acid β-oxime

“…A single crystal of oxime (--)-(1) was heated on a microscope glass slide to 353 K for 5-10 min. The slide was removed from the hot plate and, after 3-5 s, the crystal was sprayed with a mixture of yellow flowers of sulfur, carmine and lycopodium powder dyed with methyl violet as described earlier (Patil, Curtin & Paul, 1985).…”