Colorimetric chemosensors from polydiacetylene containing salicylic acid or boronic acid

Abstract

In this work, six dicetylene monomers containing boronic acid are prepared. The amido boronic diacetylene monomers such as 10,12-pNB-PCDA (1a), 10,12-mNB-PCDA (2a) 6,8-mNB-NCDA (3a) and the ester boronic acid diacetylene monomers such as 10,12-pEB-PCDA (4e), 10,12-mEB-PCDA (5e) and 6,8-pEB-NCDA (6e) are synthesized in 2 steps. All synthesized monomers can undergo molecularly self-assemble in aqueous media and are polymerized by UV 254 nm irradiation to give the blue PDA sols except 6,8-pEB-NCDA (6e). The thermochromisms of PDA blue sols are investigated using UV-vis spectroscopy with temperature probe in the range between 25-90℃. In the case of amido PDA containing meta boronic acid side chain such as 10,12-mNB-PDA (2a) and 6,8-mNB-PDA (3a), the complete reversibility of blue to red color transition is observed while 10,12-pNB-PDA (1a) containing para substituted boronic acid display partially thermochromic reversibility. On the other hand, all ester PDA analogues such as 10,12-pEB-PDA (4e) and 10,12-mEB-PDA (5e) demonstrate thermochromic irreversibility. Effects of solvent vapors, UV-light, pH and surfactants on color transition of the PDA are tested only small color changes are observed for the amide PDA while strong color transition is apparent for the ester. This work provides new structured of thermochromically reversible PDA containi