Synthesis and biological studies of amphiphilic carbazole pyridinium conjugates

Amphiphilic carbazole pyridinium conjugates are synthesized and characterized by IR, 1H and 13C NMR and ESI-MS spectrometry. The pyridinium group is attached on the 3-position of the carbazole ring and long alkyl chains are linked to the central N atom. The introduction of a pyridinium group afforded water-soluble carbazole derivatives with significant bathochromic shifts in their absorption and emission spectra. As compared to the parent N-butylcarbazole compound, carbazole pyridinium conjugates exhibited 50 nm red-shifted absorption maxima. Similarly, the carbazole pyridinium conjugates displayed 143-147 nm red-shifted emission maxima in solution. In addition, large Stokes shifts (5747-7558 cm-1) were observed for the conjugates in solution. The cell penetrable amphiphilic carbazole pyridinium conjugates exhibited cytoplasmic distribution in A549 cells.