A family of polymeric 1-dimensional chains of iron(II) species showing the spin-crossover phenomenon has been synthesized using 4-n-alkyl-1,2,4-triazoles as bridging ligands. The influence of the length of the alkyl tails on the triazole ligands on characteristic features of the spin transition was studied, showing degrading of steepness with increasing length. A set of four counter ions has been used to access a wider range of transition temperatures. Large hysteresis loops are detected with small tails, mainly for the methyl and ethyl substituted products. In most cases longer tails
weaken co-operativity and hysteresis gradually decreases to zero. However it is shown that with certain anions hysteresis remains, even with very long tails on the triazoles. Weakening of the co-operativity mainly arises from a diminution of the length of the polymeric chains with increasing alkyl tails on the triazole. This effect is anion dependent. A strong
interaction along the polymeric chains is confirmed.
合成了一种聚合物一维链的
铁(II)物种,表现出自旋跨越现象,采用4-n-烷基-
1,2,4-三唑作为桥联
配体。研究了烷基尾巴长度对三唑
配体自旋跃迁特征的影响,发现随着烷基尾巴长度的增加,自旋跃迁的陡峭度降低。使用了一组四种对离子,以获取更广泛的跃迁温度范围。检测到小尾巴的样品存在较大的滞回环,主要是甲基和乙基取代的产物。在大多数情况下,较长的尾巴削弱了协同作用,滞回现象逐渐减小至零。然而,研究表明,对于某些阴离子,即使在三唑上有很长的尾巴,滞回现象仍然存在。协同作用的减弱主要源于随着三唑上的烷基尾巴增大,聚合物链的长度减少。这个效应依赖于阴离子。确认了聚合物链之间存在强相互作用。