Department of Chemical Sciences and Technologies, University of Rome "Tor Vergata" , Via della Ricerca Scientifica 1, 00133 Rome, Italy.
Wallenberg Wood Science Center (WWSC), Department of Fiber and Polymer Technology, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden.
Biomacromolecules. 2015 Sep 14;16(9):2979-89. doi: 10.1021/acs.biomac.5b00882. Epub 2015 Aug 24.
A pH- and light-responsive polymer has been synthesized from softwood kraft lignin by a two-step strategy that aimed to incorporate diazobenzene groups. Initially, styrene oxide was reacted with the phenolic hydroxyl groups in lignin, to offer the attachment of benzene rings, thus creating unhindered reactive sites for further modifications. The use of advanced spectroscopic techniques ((1)H and (31)P NMR, UV and FTIR) demonstrated that the reaction was quantitative and selective toward the phenolic hydroxyl groups. In a second step, the newly incorporated benzene rings were reacted with a diazonium cation to form the target diazobenzene motif, whose formation was again thoroughly verified. As anticipated, the diazobenzene-containing kraft lignin derivatives showed a pH-dependent color change in solution and light-responsive properties resulting from the cis-trans photoisomerization of the diazobenzene group.
已经通过两步策略从软木硫酸盐木质素合成了一种对 pH 值和光有响应的聚合物，该策略旨在引入重氮基团。首先，氧化苯乙烯与木质素中的酚羟基反应，提供苯环的附着，从而为进一步修饰创造无阻碍的反应位点。使用先进的光谱技术（（1）H 和（31）P NMR、UV 和 FTIR）表明，该反应是定量的，且对酚羟基具有选择性。在第二步中，新引入的苯环与重氮阳离子反应形成目标重氮苯结构，其形成再次得到了彻底验证。正如预期的那样，含有重氮苯的硫酸盐木质素衍生物在溶液中表现出 pH 值依赖性的颜色变化，并且由于重氮苯基团的顺反光异构化而具有光响应特性。
