A fluorenylidene-acridane that becomes dark in color upon grinding – ground state mechanochromism by conformational change

Suzuki, Tsuyoshi; Okada, Hiroshi; Nakagawa, Takafumi; Komatsu, Kazuki; Fujimoto, Chikako; Kagi, Hiroyuki; Matsuo, Yutaka

doi:10.1039/c7sc03567e

Cited by 60 publications

(53 citation statements)

References 38 publications

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“…The condensation of malononitrile and acridone carbonyl to provide dicyanomethylenated acridone is a commonly used method not only to adjust the energy levels but also to endow the resulted molecules interesting properties, such as tuneable emission in solid state, crystal‐jumping upon heating . The introduction of fluorene to the carbonyl position of acridone affords fluorenylidene‐acridane with mechanochromism by conformational change . Acridone also plays a role of stator in molecular motors after coupling some special groups at the carbonyl group .…”

Section: Introductionmentioning

confidence: 99%

Effects of N‐Substitution on the Property of Acridone

et al. 2019

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A variety of N‐substituted acridone derivatives were synthesized to make a comparison of their properties according to the number of acridone unit and the nature of substituent. The spectroscopic and electrochemical investigations show that the properties of N‐substituted acridone derivatives are substituent‐dependent. With benzene, biphenyl, fluorene and carbazole as linkers, the acridone derivatives demonstrate the properties of acridone itself due to a very weak intramolecular charge transfer (ICT) between acridone and the linker. However, significant ICT process is observed when the electron withdrawing groups are involved to form the donor–acceptor systems with acridone as the electron donating groups, which is different from the previously reported results of which acridone is usually used as an electron acceptor. Moreover, thermally activated delayed fluorescence (TADF) is observed with anthraquinone as linker. The theoretical calculations reveal that the N‐substitutions have more influences on the locations and energy levels of the LUMOs than those of the HOMOs.

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Section: Introductionmentioning

confidence: 99%

Effects of N‐Substitution on the Property of Acridone

et al. 2019

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“…The yellow crystalline solid of N ‐methyl fluorenylidene‐acridane showed color transition to dark green upon grinding in agate mortar, confirmed by appearance of broad peak at 700 nm in UV‐visible spectra, which disappeared on exposure to chloroform vapor suggests the reversibility in mechanochromism. Furthermore, the effect of varying N ‐alkyl chain lengths on crystalline‐amorphous transition analyzed reveal steric effects gave stable conformations for methyl group and longer alkyl chain …”

Section: Utilization Of External Stimuli Sourcesmentioning

confidence: 99%

“…Molecular structures of stress/strain/pressure responsive systems References[67][68][69][70][71][72][73][74].…”

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confidence: 99%

Recent Advances on Stimuli‐Responsive Smart Materials and their Applications

2019

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Stimuli‐responsive materials have raised major attention in digital technology, sensors and biomedical applications owing to quick response towards external stimuli, for example light, voltage, pressure, temperature, mechanical friction and pH. Nevertheless, action of external stimuli on organic materials affects their internal physico‐chemical properties and facilitates improved thermal/photo stability, tuning detection sensitivity, accuracy and biocompatibility. This review article highlights recent progress on stimuli‐responsive materials with mixed valence species, viologens, twisting chirality, crystalline/amorphous, sol‐gel phase transitions and resulting supramolecular nanostructures via non‐covalent interactions. These materials can be applied in flexible electronics, drug delivery, detection of pollutants and bioimaging. Thus, the demand for widespread research on development of stimuli‐responsive materials are requisite to resolve the challenges pertaining to stability and sensitivity of devices for design in comprehensive technology.

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“…Bistricyclic aromatic enes (BAEs) [1] are ac lass of overcrowded alkenes that have recently attracted interest as functional molecules for molecular machines [2] and chromism. [3,4] BAEs are composed of two tricyclic aromatic systems connected through an alkene,a nd have received special attention since they were discovered more than 100 years ago. [1,5] Among the various forms of chromism, the thermochromism of BAEs was the first to be discussed in depth, [6] and thus they are referred as thermochromic ethylenes.…”

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confidence: 99%

“…[1,5] Among the various forms of chromism, the thermochromism of BAEs was the first to be discussed in depth, [6] and thus they are referred as thermochromic ethylenes. [6b] Upon heating, the color changes from light to dark, and this change can also be brought about by the application of pressure (piezochromism) [4,7] and light (photochromism). [8] This color change is triggered by ac onformational change from af olded conformer to at wisted conformer.T he latter shows strong absorption of light as ar esult of ac hargetransfer band in the long-wavelength region.…”

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confidence: 99%

Mechanochromism, Twisted/Folded Structure Determination, and Derivatization of (N‐Phenylfluorenylidene)acridane

et al. 2019

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N-Phenylfluorenylidene)acridane (Ph-FA) compounds with electron-withdrawing and -donating substituents (H, MeO,P h, NO 2 ,B r, F) at the para position of the phenyl group were successfully synthesized by Barton-Kellogg reactions of N-aryl thioacridones and diazofluorene.B yu sing the substituent on the nitrogen atom to alter the electronic properties,both the folded and twisted conformers of p-NO 2 -C 6 H 4 -FA could be crystallographically characterized, which enabled the charge transfer from the electron-donating acridane moiety to the electron-accepting fluorenylidene moiety to be understood. Ground-state mechanochromism, thermochromism, vapochromism, and proton-induced chromism were demonstrated between the folded and twisted conformations of the conformers.P rotonation and chemical oxidation of Ph-FAg ave two stable acridinium compounds,n amely,t he fluorenylacridinium and acridinium radical cations.T he present study will contribute to the development of functional dyes and organic semiconductors.

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A fluorenylidene-acridane that becomes dark in color upon grinding – ground state mechanochromism by conformational change

Abstract: We report mechanochromic color change controlled by conformational change (folded and twisted conformers) of fluorenylidene-acridanes (FAs).

Cited by 60 publications

References 38 publications

Effects of N‐Substitution on the Property of Acridone

Effects of N‐Substitution on the Property of Acridone

Recent Advances on Stimuli‐Responsive Smart Materials and their Applications

Mechanochromism, Twisted/Folded Structure Determination, and Derivatization of (N‐Phenylfluorenylidene)acridane

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