Mechanofluorochromism of (D–π–)₂A-type azine-based fluorescent dyes

Abstract

Bathochromic or hypsochromic shift-type mechanofluorochromism (b-MFC of h-MFC) was found for (D–π–)2A-type azine-based fluorescent dyes: grinding of the recrystallized dyes induced bathochromic or hypsochromic shifts of the fluorescence bands.

Synthesis, optical and electrochemical properties of (D–π)2-type and (D–π)2Ph-type fluorescent dyes

“…The dichloromethane extract was dried over anhydrous MgSO 4 , filtrated, and concentrated. The residue was chromatographed on silica gel (ethyl acetate/hexane 1:4 ) to give OTK-2 (19 mg, yield 27%) and OTT-2 (9 mg, yield 14%) as a light yellow solid and an orange solid, respectively; the characterization data for OTK-2 are in agreement with those reported in the literature[33]; OTT-2: mp >300 °C; FTIR (ATR) ν: 1591, 1491, 1460 cm −1 ; 1 H NMR (500 MHz, CD 2 Cl 2 ) δ 0.76-1.02 (m, 6H), 1 23. 1.38 (m, 4H), 1.71-1.81 (m, 4H), 4.12-4.21 (m, 4H), 6.95 (dd, J = 1.8 and 8.4 Hz, 2H), 7.01-7.05 (m, 4H), 7.10-7.16 (m, 10H), 7.24-7.31 (m, 10H), 7.39 (d, J = 3.8 Hz, 2H), 7.50 (dd, J = 1.4 and 8.0 Hz, 2H), 7.59 (d, J = 1.2 Hz, 2H), 7.93 (d, J = 8.3 Hz, 2H), 7.99 (d, J = 8.0 Hz, 2H) ppm; 13 C NMR (125 MHz, CD 2 Cl 2 ) δ 14.04, 20.85, 31.44, 43.04, 105.37, 105.84, 117.54, 117.56, 118.73, 120.46, 121.16, 122.94, 122.96, 124.02, 124.36, 124.84, 129.55, 131.14, 136.68, 141.67, 142.73, 144.74, 146.92, 148.61 ppm; HRMS (APCI) m/z (%): [M + H + ] calcd.…”

“…Using a toluene solution containing 1,3-diiodobenzene and (diphenylamino)carbazole-thiophenestannane derivative 1 [33] in the presence of Pd(PPh 3 ) 4 , the (D-π) 2 -type and (D-π) 2 Phtype fluorescent dyes OTK-2 [33] and OTT-2 were obtained by Stille coupling of 1 with 1,3-diiodobenzene and oxidative homocoupling of 1, respectively (Scheme 1).…”

“… (a) Photoabsorption and (b) fluorescence (λ ex = λ max,abs ) spectra of OTK-2 [ 33 ] and OTT-2 in toluene. (c) Solid-state UV–vis diffuse reflection–absorption and (b) and (d) fluorescence spectra (λ ex = 484 nm for OTK-2 [ 33 ] and 512 nm for OTT-2 ) of OTK-2 and OTT-2 in the solid state. Insets in (a) and (b): color and fluorescence images of OTK-2 (left) and OTT-2 (right) in toluene.…”

“…Insets in (c) and (d): color and fluorescence images of OTK-2 (left) and OTT-2 (right) in the solid state. The photos depicted as insets in Figure 1a –d were reproduced from [ 33 ] (“Mechanofluorochromism of (D–π–) 2 A-type azine-based fluorescent dyes, © 2022 K. Takemura et al, published by the Royal Society of Chemistry, distributed under the terms of the Creative Commons Attribution 3.0 Unported License, https://creativecommons.org/licenses/by/3.0/).…”

“…In our previous work [33], we have reported the synthesis, optical and electrochemical properties of the (D-π) 2 Ph-type fluorescent dye OTK-2 with two (diphenylamino)carbazolethiophene units as D-π moiety connected through a phenyl ring (Scheme 1). The ICT-based photoabsorption and fluorescence bands of OTK-2 appear in a shorter wavelength region than those of the corresponding (D-π) 2 A-type fluorescent dye having an azine ring (pyridine, pyrazine or triazine ring) as a substitute for the phenyl ring.…”