In this paper, the 275-223 K region is referred to as the medium-temperature (MT) state for convenience. The a-axis length of 1 increases with decreasing temperature, whereas its b-axis length, c-axis length, and cell volume decrease. In other words, the needle-like crystals become long and slim upon cooling. The elongation ratio of the crystals associated with the decrease in temperature was observed using optical microscopy (Figure and Table ). The increase in a-axis length correlated with the magnitude of disorder of the dodecyl groups. The heavy thermal motion of the dodecyl chains in the HT phase prevented the porphyrin columns from approaching each other, whereas the suppressed thermal motion of the dodecyl chains upon cooling decreased the intercolumnar distances (Figure ). Owing to the chemical pressure from adjacent columns, the intracolumnar molecular distances increased, resulting in an increase in a-axis length. thermal motion, its flexibility should depend on the temperature. To briefly examine the temperature dependence of the flexibility of 1, we attached a weight (1.168 mg of Al) to the tip of 1 (length: 5.7 mm) and cooled the crystal in a refrigerant-free cooling device sealed with an insulated window. Figure summarises the deformation of the crystal with the weight load upon cooling and heating (Movie 2). Surprisingly, the crystal bent during cooling from 298 to 265 K, indicating that the crystal softens as the temperature decreases. This behaviour is unusual because typical solids harden with decreasing temperature. A further decrease in temperature from 265 to 251 K straightened the crystal owing to curing. The heating process induced a crystal deformation identical to that observed during the cooling process, indicating that the deformation of the crystal with changing temperature is reversible.