Figure 4. Reversible shrinkage and expansion of crystal 1.

(a) Reversible shrinkage and expansion of the prismatic crystal on alternate heating and cooling at a rate of 5 K min⁻¹ in the range 228–253 K. The crystal was glued onto a nylon loop and enveloped in a temperature-controlled stream of dry nitrogen gas. The crystal exhibits shrinkage and expansion along the long axis of the crystal in response to temperature. The reversible changes were recorded for 10 cycles without breaking the single-crystal state. (b) The increase in crystal size from ∼0.20 (L_b) to 0.21 mm (L_b′) along the [010] direction, and the contraction by ∼0.05 mm (ΔL_c) (from about 0.83 to 0.78 mm) during cooling from 253 to 228 K.