Red to Near‐Infrared Mechanochromism from Metal‐free Polycrystals: Noncovalent Conformational Locks Facilitating Wide‐Range Redshift

Abstract

Figure 5. a) Normalized PL spectra of MPCbZ during the hand-actuated grinding process. b) Powder X-ray diffraction (PXRD) patterns and time-resolved spectra c) of Re-phase in the pristine state and after slight and full grinding. d) The absorption spectra of MPCbZ in the Rephase and full-grinding state.

Luminescence in Crystalline Organic Materials: From Molecules to Molecular Solids

“…[ 368b ] In fact, PL color changes upon external stimuli can be considerable with maximum shifts of ≈0.5 eV, [ 203,282 ] for instance blue↔green, light‐blue↔yellow, green↔red, [ 369 ] or, as recently reported, red↔near infrared. [ 370 ] Even more pronounced color shifts can be achieved by using co‐crystal strategies, as discussed in the following.…”

Mechanochromic luminogens with hypsochromically shifted emission switching property: recent advances and perspectives

“…[67][68][69][70][71][72][73][74][75][76] Zhu et al reported a benzothiadiazole based luminogen that exhibits a spectral shift of 160 nm on grinding. 77 Larger spectral shift results in high contrast mechanochromism and hence is useful for fabricating strain sensing devices. 78 In recent years, organic molecules comprising of an electron-donor (D) moiety and an electron acceptor (A) moiety have surfaced as promising candidates for mechanoresponsive materials.…”

“…67–76 Zhu et al reported a benzothiadiazole based luminogen that exhibits a spectral shift of 160 nm on grinding. 77 Larger spectral shift results in high contrast mechanochromism and hence is useful for fabricating strain sensing devices. 78…”

Luminescent polymorphic crystals: mechanoresponsive and multicolor-emissive properties

“…3d). 45 Two polymorphic crystals 4-R (P2 1 /c) and 4-N (P1 ¯) were obtained from a dichloromethane/hexane mixed solution of 4 and showed red and NIR emission at 615 and 727 nm, respectively. In response to grinding stimuli, the fluorescence maximum of 4-R changed to 775 nm.…”