Phenothiazine Decorated Carbazoles: Effect of Substitution Pattern on the Optical and Electroluminescent Characteristics

Abstract

A series of thienylphenothiazine decorated carbazoles were synthesized and characterized by optical, electrochemical, thermal, and theoretical investigations. Absorption spectra of the compounds are influenced by the substitution pattern and chromophore number density. Compounds containing 2,7-substitution exhibited red-shifted absorption, while the chromophore loading on the other positions led to the increment in molar extinction coefficients due to the increase in the chromophore density. Multiple substitutions resulted in twisting of chromophores and affected the conjugative delocalization of the π-electrons, which produced shorter wavelength absorption for the 2,3,6,7-tetrasubstituted derivative. Interestingly, the compounds exhibited excited-state solvatochromism attributable to the structural reorganization-induced electronic perturbations. The solvatochromic data are supportive of a general solvent effect, which is further confirmed by Lippert-Mataga correlation. End-capping with butterfly shaped phenothiazine restrained the formation of molecular aggregates in the solid state. All of the compounds displayed exceptional thermal stability attributable to the rigid carbazole building block. Solution processed OLED fabricated using the new materials as emitting dopants in 4,4'-bis(9H-carbazol-9-yl)biphenyl host exhibited bluish green electroluminescence.

NLOphoric Triphenylamine Derived Donor‐π‐Acceptor‐π‐Donor Based Colorants: Synthesis, Spectroscopic, Density Functional Theory and Z‐scan Studies

“…The Φ F decreased with the increase in the polarity of the solvent indicating that nonradiative relaxation pathway is more preferred in polar solvents than in nonpolar solvents. Large Stokes shift and decreased quantum yield in the polar environment cannot originate from geometry relaxation alone, ICT may be responsible for low quantum yields . More drastic effects for 5c support the above hypothesis where planarization may smoothen CT between julolidine and dicyanovinylene.…”

N‐Ethyl Carbazole Derived D‐π‐A‐π‐D Based Fluorophores: Consolidated Spectroscopic, Viscosity and DFT Studies

“…This indicates that in the polar solvents, non‐radiative relaxation pathway is more preferred than in non‐polar solvents. In the polar environment, geometry relaxation alone cannot effect large Stokes shift and reduced quantum yield, ICT may be responsible for low quantum yields . More drastic effects for 5 c support the above hypothesis where planarization between julolidine and dicyano vinylene can smoothen CT. On comparing the synthesized fluorophores with the reported analogue 1 , it is observed that substituting different donors of varying donating strength at the opposite end of the fixed donor results in enhanced optical properties.…”

Microwave‐Expedited Green Synthesis, Photophysical, Computational Studies of Coumarin‐3‐yl‐thiazol‐3‐yl‐1,2,4‐triazolin‐3‐ones and Their Anticancer Activity

“…The geometries of these compounds were optimized under gas phase by using (TD‐DFT) with the Becke's three‐parameter functional that was hybridized with the Lee‐Yang‐Parr correlation functional (B3LYP) and 6–31G * basis set. To the B3LYP functional tends to over delocalize the wave functions …”