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Two AIE active α-cyanostilbene fluorophores substituted with octyl and hexadecyl chains were synthesized and examined for their absorption and fluorescence properties. The alkoxy substitution tunes the self-assembly in water and exhibits an intensity enhanced bathochromic shift, resulting in well-defined nanospheres with the formation of nice dendrimeric structures. Monte Carlo simulations validate our experimental observations and show the greater propensity of self-assembly formation for cyanostilbene containing a hexadecyl chain compared to a derivative containing an octyl chain. The results are substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scattering (DLS) studies. Such tunable self-assembled nanostructures seem promising for material and biological applications.

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Neutral and cationic diarylbutadienes with pyridine and pyridinium groups as electron acceptors with dimethylamine and diphenylamine as electron donors were synthesized. The absorption and emission properties of these dienes were investigated in homogeneous organic solvents and in sodium cholate media. In strongly polar solvents, both neutral and cationic fluorophores exhibit a bathochromic shift of emission characteristics of intramolecular charge transfer (ICT) excited states. The presence of a strongly electron withdrawing pyridinium group induces large absorption (∼480 nm) and emission wavelength shifts (near ∼680 nm) in polar solvents. This solvatochromic behavior is utilized as a tool to examine the fluorophore-sodium cholate interaction. Significant hypsochromic emission shifts (up to ∼66 nm) and concomitant intensity enhancement (up to 32-fold) are seen for these fluorophores in the presence of increasing concentrations of sodium cholate. Fluorescence lifetime measurements reveal biexponential decay patterns indicating the binding of molecules in distinct cholate environments.