Fluorescent dyes for moisture detection in organic solvents: Push-pull based phenothiazine aldehydes with large Stokes shifts

Systematic photophysical, thermal and electrochemical analysis of a series of phenothiazine cored conjugated aromatic unit appended D–π–A based high-solid state luminescent materials: their applications in reversible mechanofluorochromic and volatile acid sensing

“…It is well recognized that the smaller the dihedral angle between the donor and acceptor, the stronger the electronic coupling. 46 The CT band in the visible region, i.e., 405 nm, for PT-C2-(An) 2 , results from the low-lying excited state leading to a low energy band gap (3.03 eV) (Fig. S37 and Table S1, ESI †) as obtained from DFT calculations.…”

“…However, PT-C2-(An) 2 , PT-C2-(Pn) 2 and PT-C2-(Pr) 2 demonstrated high energy p-p* (S 0 -S 2 ) transitions, in the range of 234-290 nm largely as a result of the higher energy necessitated for the electrons to circumnavigate across the larger aromatic rings, i.e., An, Pn and Pr units, and also could be the result of the sterically bulky nature of An, Pn and Pr units. 45,46 Sharp CT bands were noticed for PT-C2-(Ph) 2 , PT-C12-(Ph) 2 , PT-C2-(Nap) 2 , PT-C12-(Nap) 2 , PT-C2-(An) 2 , and PT-C2-(Pr) 2 . In contrast, a weak and broad ground state CT band centered at 365 nm was observed in PT-C2-(Pn) 2 .…”

Multi Stimuli Responsive Non‐Doped Red Emitting AIEE Active Phenothiazine‐Based Chalcones: Crystal Structure, Solvatochromism, Turn‐on Mechanofluorochromism and Acidochromism

“…These peaks reverted to their original spectral position (Figures S30 and S32) upon subsequent addition of TEA, which clearly show the involvement of carbonyl group in protonation. [105] Nitric Acid sensing Further, the acid sensing ability of chalcones was examined by adding 0.02 mL of different acids such as HCl, H 2 SO 4 , and HNO 3 to the DCM solution (10 μM). It was observed that the addition of HCl and H 2 SO 4 did not cause any significant changes in the UV-vis and emission spectra (Figure 13, Figures S35 and S36).…”

“…The carbonyl group incorporated as an acceptor moiety in push-pull molecules may also form H-bonding with the oxygen atom. [103][104][105][106] To investigate the ability of chalcones to sense the presence of trifluoroacetic acid, spectrophotometric titrations were performed in dichloromethane at 10 μM concentration. Upon increasing the concentration of TFA from 0 to 18.8 mM, the absorption band corresponding to ICT (λ em = 448 nm) red shifted by 22 nm in C2, whereas the aforementioned band was red shifted by 20 nm and 16 nm upon addition of 0-18.1 mM and 0-13 mM TFA for C3 and C4, respectively (Figure S24).…”

Phenothiazine-Based Luminophores with AIE, Solvatochromism, and Mechanochromic Characteristics

“…Phenothiazine is an important heteroatom-containing organic small molecule with unique molecular structure characteristics. The electron-rich atoms, nitrogen and sulfur, endow phenothiazine with stronger electron-donating ability than many other N-heterocycle structures such as carbazole, triphenylamine, and tetrahydroquinoline. − In addition, the nonplanar “butterfly-like” conformation is conducive to the construction of twisted fluorescent molecules, which is extremely beneficial to the luminescence in the condensed state. − This unique conformation gives phenothiazine a great advantage in designing new AIE molecules. − Coupled with the availability of multiple modifiable sites and ease of functionalization, all of these advantages make phenothiazine an excellent candidate for constructing the D–A architecture with excellent optoelectronic properties.…”