Vicente Ana I, Joseph Abhinav, Ferreira Liliana P, de Deus Carvalho Maria, Rodrigues Vítor H N, Duttine Mathieu, Diogo Hermínio P, Minas da Piedade Manuel E, Calhorda Maria José, Martinho Paulo N
Centro de Química e Bioquímica , Faculdade de Ciências , Universidade de Lisboa , Campo Grande , 1749-016 Lisboa , Portugal . Email:
BioISI , Faculdade de Ciências , Universidade de Lisboa , Campo Grande , 1749-016 Lisboa , Portugal.
Chem Sci. 2016 Jul 1;7(7):4251-4258. doi: 10.1039/c5sc04577k. Epub 2016 Mar 17.
The thermosalient effect is still a rare and poorly understood phenomenon, where crystals suddenly jump, bend, twist or explode upon undergoing a thermally activated phase transition. The synthesis and characterisation of the new spin transition Fe(iii) compound [Fe(5-Br-salEen)][ClO] (salEen = -ethyl--(2-aminoethyl)salicylaldiminate) is described and its thermosalient behaviour reported. It is the first example of a thermosalient effect with a spin transition and magnetic, calorimetric, diffraction, microscopy and computational studies are used to characterise these effects. Both thermosalient effect and spin transition occur around 320 K upon heating and are accompanied by an anisotropic unit cell change with conservation of crystal symmetry that causes a large enough stress of the crystal lattice to induce crystal explosion. This stress can ultimately be traced back to a diffusionless and distortive structural perturbation resulting in a coupled spin transition-thermosalient effect.
热致跃变效应仍然是一种罕见且鲜为人知的现象，在这种现象中，晶体在经历热激活相变时会突然跳跃、弯曲、扭曲或爆炸。本文描述了新型自旋转变铁（III）化合物[Fe(5-Br-salEen)][ClO]（salEen = -乙基--(2-氨基乙基)水杨醛亚胺）的合成与表征，并报道了其热致跃变行为。这是具有自旋转变的热致跃变效应的首个实例，利用磁性、量热、衍射、显微镜和计算研究对这些效应进行了表征。加热时，热致跃变效应和自旋转变均在320 K左右发生，并伴随着各向异性晶胞变化，同时晶体对称性保持不变，这会导致晶格产生足够大的应力从而引发晶体爆炸。这种应力最终可追溯到一种无扩散且有畸变的结构微扰，从而导致了自旋转变 - 热致跃变效应的耦合。
