Enhanced Sensitivity and Piezochromic Contrast through Single‐Direction Extension of Molecular Structure

Abstract

Two piezochromic materials containing phenanthro[9,10-d]imidazole and tetraphenylethylene (M1 and M2) were developed. A supra-amplification piezochromic effect originating from their various long-to-short axis ratios was discovered in high-pressure experiments. Based on the linear relationship between applied pressure and emission-peak wavelength during pressurizing and depressurizing cycles, quantitative sensitivity for piezochromism could be denoted. M2 displayed higher piezochromic contrast (102 nm) and better sensitivity (11.19 nm GPa ) than M1 (69 nm and 6.12 nm GPa ), which helps to develop a more comprehensive general strategy to evaluate pressure-responsive performance.

High‐Contrast Polymorphic Luminogen Formed through Effect of Tiny Differences in Intermolecular Interactions on the Intramolecular Charge Transfer Process

“…[ 10 ] The absorption sidebands of 1CA , 1CB , and 1CC are sequentially shifted and broadened to longer wavelengths, indicating that their energy gaps are gradually reduced. [ 11 ] That is to say, their ICT process are strengthened in turn, so that their emission colors are redshifted.…”

Stimuli‐Responsive Luminescent Properties of Tetraphenylethene‐Based Strontium and Cobalt Metal–Organic Frameworks

“…A Raman peak at 998 cm À1 is attributed to the ring breathing, 1130 cm À1 is attributed to the stretching vibration of the C À C single bond formed between ethylene core and adjacent benzene ring in ETTB, 1605 cm À1 is attributed to the C=C stretching vibrations of benzene ring. [18] With increasing pressure, majority of the Raman peaks exhibited obvious blue shifts and gradual reductions in peak intensity (Figure 4), which signified the enhancement in intermolecular interactions. [19] Meanwhile, the absence of peak degeneration and emergence of new peak indicated that no phase or defect transition occurs during the whole pressurization process.…”

Ultrahigh‐Sensitive Compression‐Stress Sensor Using Integrated Stimuli‐Responsive Materials

“…Imaging and measuring mechanical stresses, such as, compression, friction, and tensile stresses, are some of the challenging goals in recent materials science. [ 1–21 ] Mechano‐responsive materials exhibit visible and/or fluorescent color changes through microscopic structural changes including the chromophore at the molecular scale with the application of macroscopic mechanical stresses. Transfer of macroscopic mechanical stresses to microscopic structures is important for the design of mechano‐responsive color‐changing materials.…”

“…However, compression stress was detectable in the range 10 6 –10 10 Pa, namely the order of MPa and GPa, using mechano‐responsive materials in previous works ( Figure e and Figure S1, Supporting Information). [ 7–11,13,15,17,20,21,27–33 ] The facts indicate that the molecular motion leading to color changes is not easily induced by weak compression stress. New strategies are required for the measurement of weak stresses beyond approaches in molecular sciences.…”