Jumping Crystal of a Hydrogen‐Bonded Organic Framework Induced by the Collective Molecular Motion of a Twisted π System

Abstract

There is alimited number of reports on mechanically responsive molecular crystals,i ncluding thermo-responsive and light-responsive crystals.Rigid ordered molecular crystals with aclose-packing structure are less able to accept distortion, which hampers the development of such molecular crystals. The thermosalient effect, or "crystal jumping", refers to athermo-responsive system that converts heat into mechanical force by thermally induced phase transition. While they have recently attracted attention as potential highly efficient molecular actuators,less than two dozens of thermosalient molecular crystals have been reported to date,a nd the design of such molecules as well as how they assemble to express at hermosalient effect are unknown. Herein, we demonstrate how the cooperative molecular motion of twisted p units could serve to develop at hermo-responsive jumping molecular crystal with ah ydrogen-bonded organic framework (HOF) of tetra-[2,3]thienylene tetracarboxylic acid (1). The cooperative change in the molecular structure triggered by the desolvation of THF in the channel of the HOF structure induced not only ac hangei nt he structure of HOF but also mechanical force. Hydrogen bonding interactions contributed significant thermal stability to maintain the HOF assembly even with ad ynamic structural change.

A Permanent Porous Hydrogen-Bonded Framework with Room-Temperature Phosphorescence

“…As shown in Figure b, BPMCz-P1 exhibited comparatively low N 2 adsorption, with uptakes of about 35.5 cm 3 /g (1.58 mmol/g) at 77 K. In contrast, BPMCz-P1 scarcely adsorbed N 2 at 273 and 298 K. This is possibly due to the strong interaction between the narrow channel window and nitrogen that hinders gas diffusion into the material, which is a common phenomenon in the research field of HOFs . Interestingly, it showed a comparatively high CO 2 uptake of 57.5 cm 3 /g (2.57 mmol/g) at 273 K. The CO 2 uptake amount of BPMCz-P1 is relatively higher than those of some reported HOFs, such as HOF-11a (30.5 cm 3 /g) and HOF-1 (19.8 cm 3 /g) . The calculated Brunauer–Emmett–Teller (BET) surface area based on the isotherm of CO 2 at 196 K is 146.3 m 2 /g.…”

“…45 Interestingly, it showed a comparatively high CO 2 uptake of 57.5 cm 3 /g (2.57 mmol/g) at 273 K. The CO 2 uptake amount of BPMCz-P1 is relatively higher than those of some reported HOFs, such as HOF-11a (30.5 cm 3 /g) 46 and HOF-1 (19.8 cm 3 /g). 47 The calculated Brunauer−Emmett−Teller (BET) surface area based on the isotherm of CO 2 at 196 K is 146.3 m 2 /g. The sorption isotherms showed a typical type-I isotherm with a very sharp uptake at a low pressure, indicating its microporous nature.…”

Dynamic Motion of Twisted π System-Induced Temperature-Dependent Dielectric Response in the Neat Liquid State

“…Thus, we used a Pd(0)-catalyzed coupling reaction 32 to obtain desired material 1 in moderate yield. The syntheses of 2 and 3 were started from the tetra [2,3]thienylene tetracarboxylic acid (5) 21 and tetrabromotetra [2,3]thienylene (6). 28 The typical amidation of 5 via the corresponding acid chloride and Suzuki coupling of 6 with 7 gave 2 and 3, respectively.…”

“…14 For example, the rotation and flipping motion of molecule/functional groups have been used to create materials with ferroelectric, 15−18 temperature-dependent fluorescent 19 and thermodynamic actuation properties. 20,21 While these materials have been developed mainly in the relatively static solid or liquid crystalline phase with several regularities of the molecular assemblies, such liquid materials could also be created with an appropriate molecular design. In this work, we focused on liquid COT derivatives for this purpose.…”

Hydrogen-bonded porous frameworks constructed by rigid π-conjugated molecules with carboxy groups

“…HOF JLU-SOF-1-R composed of the homochiral 11 had an SA (BET) value of 460 m 2 g − 1 and selective sorption toward CO 2 [81]. Takeda et al demonstrated that twisted cyclic tetrathienylene 12 yielded a jumping HOF [82]. Stoddart et al reported that triptycene derivative 13a and 13b provided interpenetration polymorphs of H-bonded networks [83,84].…”