Tightening of the screw caused the crystal to arc. Structural mapping from the lower to the upper regions across the centre of the arc revealed that the a-axis length of the outer arc was approximately 1.7% longer than that of the inner arc. The longer and shorter a-axis lengths correspond to the MT state and HT phase, respectively, indicating the outer-and inner-arc regions adopt the MT state and HT phase, respectively. The z dependence of the a-axis length of a bent crystal is not expressed as a linear line but is fitted with a sigmoidal curve, indicating an inhomogeneous structural phase transition. These results are consistent with the proposed mechanism of softening upon cooling, where the outer-and inner-arc regions adopt the MT state and HT phase, respectively (Figure ). Figure summarises the porphyrin core structures in the inner (small z)and outer (large z)-arc regions. The molecular structures of the outer-and inner-arc regions of the straight and bent configurations were identical, and no clear difference in the magnitudes of the thermal factors on the dodecyl chains was observed. In contrast to the molecular structures, the intracolumnar molecular distances depended on the position of the arc. In the straight configuration, the intermolecular centroid-centroid distances in the outer-and inner-arc regions were similar (Figure , left). However, in the bent configuration, the intermolecular distances changed from 5.87 to 6.01 Å in the inner arc and from 5.67 to 5.81 Å in the outer arc, corresponding to a ~2.3% difference in molecular distance (Figure , right). This deformation indicates that a 60 μm-thick crystal can be bent to form an arc with a diameter of 5.2 mm, indicating high flexibility.