Dynamic Resolution of Piezosensitivity in Single Crystals of π‐Conjugated Molecules

Abstract

Ta rgeted synthesis of piezoresponsive small molecules and in-depth understanding of their mechanism is of utmost importance for the development of smart devices.T his work reports the synthesis, structure and piezosensitivity of ab ola-amphiphile 1,4-bis(pentyloxy)-2,5-bis(2-pyridineethynyl)-benzene (C5-PPB). Dependingo nt he rate of compression, two different phases in C5-PPB can be generated.T he ambient-pressure aphase is stable up to 0.8 GPa, beyond which it undergoes an isostructural transformation to b-phase, accompanied by ac learly visible elongationo ft he crystal.T his a-to-b phase transitionr equirest he sample to be compressed slowly.W hen quicklyc ompressed, phase a persistst o about 1.5 GPa, beyond which its amorphization starts, accompanied by the appearance of irregular grooves on the largest faces. Mechanical pressure also affectst he optical property of C5-PPB,w hich shows reversible mechanochromism with ag reen to cyan transformation in the emission, associated with a1 5nms hift in the maxima. The conductivity of C5-PPB as ad irect outcome of its crystal packing has also been studied.Development of purely organic p-conjugated oligomers that are light, flexible and external-stimuli responsive is highlydesirable for multifarious applicationsi ns mart devices. [1] Molecules that are capable of responding to external mechanicalf orces [2] are sought after for human-machine or robotic interfaces, sensors, security inks, memory storage, and healthcared evices. [3] In condensed forms like crystals, liquid crystals, or micelles, the

High-pressure preference for reduced water content in porous zinc aspartate hydrates

“…Thus it can be classified as an isostructural phase transition, which is quite common for metal-organic frameworks under pressure. For example, at 0.40 GPa Cd(APP) 2 NO 3 ÁNO 3 transforms between monoclinic phases, both of space-group symmetry P2 1 /c (Pó łrolniczak et al, 2018) and Co 2 (4,4 0 -bpy) 3 (NO 3 ) 4 ÁxH 2 O preserves its orthorhombic space group Ccca at p c = 6 GPa (Zhou et al, 2014), plus other known examples (Moggach et al, 2009;McKellar & Moggach, 2015;Sobczak et al, 2018;Bhattacharyya et al, 2019).…”

Self-assembled organic and hybrid materials derived from oligo-(p-phenyleneethynylenes)

“…In a slightly different approach, Maji et al further employed pyridine end groups within OPE chains, and upon solving the single-crystal structure, it was found that like OPE-4, the 1D extension was directed by weak supramolecular forces such as C-HÁ Á Áp, p-p, etc. 67 This led to a zig-zag pattern in the 1D extension. More interestingly, this particular supramolecular system portrayed pressure dependent single crystalline phase changes.…”

Oligo(phenyleneethynylene)s: Shape‐Tunable Building Blocks for Supramolecular Self‐Assembly

“…[10] Similarly, Maji and co-workers utilized an interplay of intermolecular interactions by incorporating a polar pyridine terminal into the OPE design to achieve a reversible mechanochromism-assisted emission color change, from green to cyan. [11] The above discussion points to the fundamental and functional importance of OPEs as potential building blocks for a wide range of applications. These features have motivated supramolecular chemists to rationalize and control their self-assembly behavior and the resulting photophysical and (chir)optical properties.…”