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Updated: Jan 23, 2026

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
Chlorine (Cl) - Substituted Carbazole Based A-π-D-π-a Push-Pull Chromophores as Aggregation Enhanced Emission (AEE)
Prerana K M Lokhande1, Dinesh S Patil1, Mayuri Kadam1
1Department of Dyestuff Technology, Institute of Chemical Technology, Matunga, Mumbai, 400 019, India.
Abstract:
Three new carbazole functionalized A-π-D-π-A extended chromophores 4a, 4b and 4c comprising of different chemical functional groups on C=C bond with the assistance of chlorovinylene group in π-conjugation are synthesized and investigated spectroscopically. We have investigated the effect of different electron acceptors - carboxycyanomethylene, dicyanomethylene and 2-(benzothiazol-2-yl) cyanomethylene, the effect of the insertion of chlorine in π-conjugation on photophysical properties and the effect of double acceptors. The chromophores 4a, 4b and 4c exhibited positive solvatochromism with large Stokes shifts and bright orange to red solid-state fluorescence. Amongst all the three compounds 4c exhibited maximum emission wavelength at 615 nm in DMSO. They presented characteristic twisted intramolecular charge transfer (TICT) emission. Observations exhibited that 4c containing long hexyl group in donor unit and 2-(benzothiazol-2-yl) cyanomethylene as an acceptor group formed an aggregate in the mixture of solvents and exhibited better aggregation enhanced emission (AEE) compared to the other two derivatives. Amongst the three styryls, 4c showed the highest emission intensity 299 a.u. at 90% water:DMF fraction (fw). Chromophores 4a-4c also exhibited good fluorescence response towards viscosity. Among the three fluorescent molecular rotors (FMR), 4c exhibited excellent viscosity sensitivity with x value = 0.687. The Non-linear (NLO) characters are estimated with the help of solvatochromic and computational methods using the functionals, B3LYP and CAM-B3LYP. The dyes showed large "linear polarizability (αCT)", "first order hyperpolarizability" (β) and "second order hyperpolarizability" (γ) values which show that synthesized styryls can be used as a "NLO" material. The αCT, β and γ for 4c are found to be the maximum amongst the all three dyes which can be ascribed to the smaller band gap apparent from experimental as well as DFT method.
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