Synthesis and self-assembly of spin-labile and redox-active manganese(iii) complexes
作者:Claudio Gandolfi、Tatiana Cotting、Paulo N. Martinho、Olha Sereda、Antonia Neels、Grace G. Morgan、Martin Albrecht
DOI:10.1039/c0dt01222j
日期:——
New amphiphilic and spin-labile MnIII complexes based on dianionic N4O2-hexadentate sal2trien or sal2bapen ligands, which contain OC6H13, OC12H25, or OC18H37 alkoxy substituents at different positions of the salicylidene unit were prepared (H2sal2trien = N,N′′′-bis(salicylidene)-1,4,7,10-tetraazadecane, H2sal2bapen = N,N′′′-bis(salicylidene)-1,5,8,12-tetraazadodecane). According to electrochemical measurements, these complexes undergo two (quasi)reversible redox processes. Temperature-dependent magnetic measurements revealed a high-spin configuration for all sal2trien complexes (S = 2) and gradual spin crossover for sal2bapen complexes from high to low spin (S = 1). The chain length strongly influences the spin crossover, as C18-functionalization stabilizes the low spin state at much higher temperatures than shorter alkyl chains. Moreover, long alkyl chains allow for spontaneous self-assembly of the molecules, which was investigated in single crystals and in Langmuir-films at the air–water interface. Long alkyl chains (C12 or C18) as well as a mutual syn-orientation of these molecular recognition sites were required for the Langmuir monolayers to be stable.
基于二阴离子N4O2-六齿配体sal2trien或sal2bapen的新型两亲性和自旋不稳定MnIII配合物被制备出来,这些配体在水杨醛单元上的不同位置含有OC6H13、OC12H25或OC18H37烷氧基取代基(H2sal2trien = N,N′′′-双(水杨醛)-1,4,7,10-四氮杂十二烷,H2sal2bapen = N,N′′′-双(水杨醛)-1,5,8,12-四氮杂十四烷)。根据电化学测量,这些配合物经历了两个(准)可逆氧化还原过程。温度依赖性磁性测量揭示了所有sal2trien配合物的高自旋构型(S = 2),以及sal2bapen配合物从高自旋到低自旋的渐进自旋交叉(S = 1)。链长强烈影响自旋交叉,因为C18功能化使得低自旋态在比短链烷基高得多的温度下稳定。此外,长链烷基允许分子自发自组装,这在单晶和空气-水界面上的Langmuir膜中进行了研究。为使Langmuir单层稳定,需要长链烷基(C12或C18)以及这些分子识别位点的互相同向排列。