Synthesis, photophysical properties, and density functional theory studies of phenothiazine festooned vinylcyclohexenyl-malononitrile.

A novel phenothiazine derivative conjugated with vinylcyclohexenyl-malononitrile (PTZ-CDN) was synthesized through the Knoevenagel reaction of 10-octyl-10H-phenothiazine-3,7-dicarbaldehyde with 2-(3,5,5-trimethylcyclohex-2-en-1-ylidene)-malononitrile and fully characterized. The UV-vis absorption spectra of PTZ-CDN in different solvents showed a λmax band at 497-531 nm with a high molar extinction coefficient attributed to intramolecular charge transfer (ICT) with the characteristics of a π-π* transition. Increasing the solvent polarity resulted in a bathochromic shift of λmax . The PTZ-CDN fluorescence emission spectra were more sensitive to increasing the solvent polarity than the absorption spectra; they displayed a blue shift of λem by 85 nm. To understand the behaviour of the PTZ-CDN derivative, Stokes' shift ( Δ ν ¯ ) with respect to the solvent polarity, Lippert-Mataga and linear solvation-energy relationship (LSER) models were applied in which the LSER showed better regression than the Lippert-Mataga plots (r2 = 0.9627). Finally, the TD-density functional theory (DFT) electronic transition spectra in dioxane and dimethyl formamide (DMF) were calculated. The DFT data showed that λmax resulted from the support of the highest occupied molecular orbital to the lowest unoccupied molecular orbital transition with 74% and 99% in dioxane and DMF, respectively.

Synthesis and photophysical studies on a new fluorescent phenothiazine-based derivative.

A new typical phenothiazine compound functionalized with thienyl-indandione derivative (PTZTID) was synthesized and characterized using spectral analysis (ultraviolet-visible (UV-vis) light, infrared (IR), 1 H nuclear magnetic resonance (NMR) and 13 C NMR tools). The UV-vis absorption spectra of the PTZTID solution in 1,4-dioxane showed two absorption bands attributed to localized aromatic π-π* transitions of conjugated aromatic moieties and intramolecular charge transfer with the characteristics of a π-π* transition. The fluorescence spectra exhibited a maximum emission wavelength at 580 nm. The effect of concentration on photophysical properties took the form of a minor hypsochromic shift, which was attributed to some extent to the occurrence of H-type aggregation of the PTZTID derivative. Binary solvent effects on the spectroscopic behaviour of PTZTID were measured at different H2 O/1,4-dioxane ratios. Similarly, when increasing the water content, a hypsochromic shift was observed that resulted from H-type aggregation. Furthermore, geometry and electronic configurations of PTZTID were studied at density functional theory /B3LYP level and indicated that the compound had a nonplanar (butterfly structure).