Fluorescent non-linear chiral polymer chemosensor bonded alternatively with 1,4-diethynyl-2,5-dioctyloxybenzene and (R,R)-salen for Zn2+recognition

Stereoregular non-linear chiral main chain polymers 1a–b bonded alternatively with (R,R)-salen and 1,4-diethynyl-2,5-dioctyloxybenzene moieties have been synthesized using palladium catalyzed C–C cross-coupling and Schiff base formation reactions as the key steps. These polymers are soluble in common organic solvents, and act as an effective chemosensor for the detection of Zn2+ with respect to other metal ions with enhanced fluorescence. The CD spectra observed for the polymers 1a–b could be attributed to the helical secondary structure with a low degree of inter-strand interactions. This reduced inter-strand interaction has been ascertained from the titration of pyridine to the Zn(II)-polymer 1b complex, which results in minor changes in the fluorescence emission.

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Chiral main chain polymer bonded alternatively with 1,4-diethynyl-2,6-dioctyloxybenzene and salen.[α]D20=-797 (c 0.1, CHCl3)Source of chirality: (1R,2R)-1,2-DiaminocyclohexaneAbsolute configuration: (R,R)

Chiral main chain polymer alternatively bonded with 1,4-diethynyl-2,6-dioctyloxybenzene and salen.[α]D20=-244 (c 0.1, CHCl3)Source of chirality: (1R,2R)-DiphenylethylenediamineAbsolute configuration: (R,R)