Synthesis, structure and mechanofluorochromic properties of phenothiazine-S-oxide and phenothiazine-S,S-dioxide derivatives

Authors：Zhang, Ming-Xing; Yang, Xiaofei; Tan, Fen; Zhang, Hongquan; Zeng, Guoping; Xu, Zhiqiang^*; Liu, Sheng Hua^*

Source：Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy , 2023, 292: 122427.

DOI：10.1016/j.saa.2023.122427

• Phenothiazine
• Solvatochromism
• Mechanochromic
• Self-recovering

In this work, two novel luminescent molecules containing distorted phenothiazine-S-oxide and phenothiazine-S,S dioxide skeletons were synthesized by oxidation reactions using different oxidants (m-chloroperoxybenzoic acid, acetic acid /hydrogen peroxide). The target compounds were all confirmed by 1H NMR, 13C NMR and EI-MS. Combined with the results of UV-vis absorption spectra and fluorescence emission spectra, we found that the different oxidation states of S-atom, from sulfide (+2) to sulfoxide (+4) and sulfone (+6), led to the blue, yellow -green and yellowish fluorescence of these compounds in the solid states. Subsequent studies showed that the molecule containing the phenothiazine-S-oxide skeleton exhibited obvious solvatochromism, and the increase of solvent polarity induced a red-shift in the emission wavelength. Moreover, this molecule also exhibited a rare self-recovery mechanochromatic behavior. In addition, these properties were further confirmed by theoretical calculations and X-ray single-crystal diffraction analysis.

• Institution
  武汉工程大学