Titanium–salen complexes as initiators for the ring opening polymerisation of rac-lactide
作者:Charlotte K. A. Gregson、Ian J. Blackmore、Vernon C. Gibson、Nicholas J. Long、Edward L. Marshall、Andrew J. P. White
DOI:10.1039/b518266b
日期:——
A family of bis(iso-propoxide) titanium(IV) complexes supported by tetradentate Schiff base (salen) ligands has been synthesised and characterised, including a structural determination of N,Nâ²-bis(6â²-methylenimino-2â²,4â²-di-tert-butylphenoxy)cyclohexyl-(1R,2R)-diamino titanium(IV) bis(iso-propoxide). Their suitability for initiating the ring-opening polymerisation of rac-lactide has been investigated. Polymerisation activities are shown to correlate with the electronic properties of the substituents within the salen ligand. In contrast to aluminiumâsalen initiators, electron-withdrawing substituents on the Schiff base ligand have a detrimental influence upon polymerisation activities, whereas the use of electron-donating alkoxy-functionalised ligands has allowed the highest recorded activity to date for a titanium-based initiator.
合成并表征了由四齿席夫碱(salen)配体支持的双(异丙氧基)钛(IV)配合物家族,包括 N,N-2-双(6-2-亚甲基亚氨基-2-)的结构测定2,4-2-二叔丁基苯氧基)环己基-(1R,2R)-二氨基钛(IV)双(异丙氧基)。已经研究了它们引发外消旋丙交酯开环聚合的适用性。聚合活性与 salen 配体内取代基的电子特性相关。与铝 Salen 引发剂相比,席夫碱配体上的吸电子取代基对聚合活性具有不利影响,而使用给电子烷氧基官能化配体则使钛基引发剂达到了迄今为止最高的活性记录。发起者。