Synthesis, characterization and photophysical properties of π-conjugated novel phenothiazine substituted acrylonitrile D–A derivatives: Orange to red emission

Abstract

• Phenothiazine substituted acrylonitrile derivatives are synthesized. • Optical band gap values range from 2.296 to 2.407 eV. • Measured experimental quantum yields ( φ) are range from 0.065 to 0.121. • The 5% weight loss temperatures of derivatives are in the range 170–250 °C. By utilizing palladium catalyzed Suzuki–Miyaura cross coupling reaction, a series of novel organic dyes containing phenothiazine were designed, synthesized (abbreviated as PTA-5(a–d)) in good yield and confirmed by spectroscopic methods. These bipolar dyes comprise of PTA moiety as the electron donor unit (D) and acrylonitrile as the electron acceptors/anchoring unit (A). By introducing substituents at C(3) and C(7) positions, Intramolecular Charge Transfer character of PTA was improved. Their photophysical/solvatochromic properties were examined with the assistance of DFT computations and the synthesized molecules exhibit red fluorescence with decent quantum yields. The computed and experimental results are found to be in accordance. Differential scanning calorimetry and thermogravimetric analysis showed the thermal stabilities of the compounds. The highest occupied molecular orbitals, lowest unoccupied molecular orbitals and energy band gap were computed with the help of frontier molecular orbitals. The outcome exhibit that the novel (D–A) chromophores could play important role in organic optoelectronics.