Reversible mechanofluorochromism by simple phenyl and mesitylene appended solid state emitters via crystal to amorphous transitions. (August 2022)

• Record Type: Journal Article
• Authors: Sarkar, Bhaswati; Prasad, Edamana; Gardas, Ramesh L.
• Is Part Of: Dyes and pigments. Volume 204(2022)
• Publication Date: 2022-08
• Subjects: Phenyl derivative -- Mesitylene derivative -- Aggregation-induced emission -- Mechanofluorochromism; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2022.110246
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Developing a variety of organic compounds with bright solid-state emission is highly advantageous, provided they exhibit stimuli-responsive properties. Such 'smart' materials offer a remarkable role in sensing, digital machinery, material science, and the biomedical field. Taking this into account, two phenothiazines (PT) appended vinyl-linked aryl unit (mesitylene/phenyl) two based D–π–A structures have been synthesized. The derivatives have exhibited remarkable luminescence characteristics in a diverse set of solvents due to the twisted intramolecular charge transfer (TICT) state and aggregation-induced emission enhancement properties. Surprisingly, between them, only the mesitylene derivative displays significant and highly reversible mechanofluorochromic (MFC) activity by exhibiting an emission shift from sky blue (467 nm) to cyan (482 nm). The mechanistic insight obtained from P-XRD analysis suggests crystal to amorphous transition causes bathochromic shift upon grinding. SEM analysis reveals two discrete morphologies of the MFC compound in its pristine and ground states. Additionally, DFT and TD-DFT calculations provide insight into their electronic energy levels. Furthermore, results from the electrochemical experiment indicate that they are potential candidates for developing optoelectronic devices. Graphical abstract: Image 1 Highlights: The highlights of the work are summarized below. Mesitylene and phenyl appended Phenothiazine based D–π–A structures with highly solid-state emissions were synthesized. The derivatives have exhibited remarkable luminescence characteristics in various solvents and aggregation-induced enhanced emission (AIEE) properties. Among the two structures, mesitylene derivative demonstrates noteworthy and highly reversible mechanofluorochromic (MFC) behavior by displaying fluorescence emission shift from sky blue (467 nm) to cyan (482 nm) via crystal to an amorphous phase transition. The electrochemical and photophysical studies indicate that these compounds are potential candidates in pressure sensing, vapour sensing, and redox-active organo-electronic devices.