Mączka Mirosław, Stefańska Dagmara, Gągor Anna, Pikul Adam
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, 50-422 Wrocław, Poland.
Dalton Trans. 2021 Dec 20;51(1):352-360. doi: 10.1039/d1dt03382d.
Hypophosphite hybrid perovskites have recently received widespread attention due to their diverse structural and magnetic properties, negative thermal expansion and photoluminescence behaviour. Herein, we report two new three-dimensional hybrid perovskites containing unusually large organic cations, pyrrolidinium and 2-hydroxyethylammonium. We report the crystal structures of these new manganese-hypophosphite frameworks and their magnetic and optical properties. We also report the magnetic and optical properties of two previously discovered analogues, dimethylammonium and imidazolium manganese hypophosphites. Both new compounds crystallize in a monoclinic structure, space group 2/, with ordered organic cations at room temperature. Magnetic studies show that all studied compounds are examples of canted antiferromagnets but the weak ferromagnetic contribution and the ordering temperature are significantly modulated by the type of organic cation located in the cavity of the framework. We discuss the origin of this behaviour. Upon ultraviolet excitation, all compounds exhibit broadband photoluminescence associated with the T(G) → A(S) transition of octahedrally coordinated Mn ions. The position of the PL band depends on the type of organic cation, being the most blue-shifted for the imidazolium analogue (646 nm) and the most red-shifted for the pyrrolidinium counterpart (689 nm). The most interesting property of the studied hypophosphites is, however, the strong temperature dependence of the photoluminescence intensity, suggesting the possible application of these compounds in non-contact optical thermometry.
次磷酸盐杂化钙钛矿因其多样的结构和磁性、负热膨胀以及光致发光行为，近来受到了广泛关注。在此，我们报道了两种含有异常大的有机阳离子——吡咯烷鎓和2-羟乙铵的新型三维杂化钙钛矿。我们报道了这些新型锰-次磷酸盐骨架的晶体结构及其磁学和光学性质。我们还报道了两种先前发现的类似物——二甲基铵和咪唑鎓锰次磷酸盐的磁学和光学性质。两种新化合物在室温下以单斜结构结晶，空间群为2/，有机阳离子有序排列。磁性研究表明，所有研究的化合物都是倾斜反铁磁体的例子，但框架空腔中有机阳离子的类型对弱铁磁贡献和有序温度有显著调制作用。我们讨论了这种行为的起源。在紫外激发下，所有化合物都表现出与八面体配位锰离子的T(G)→A(S)跃迁相关的宽带光致发光。PL带的位置取决于有机阳离子的类型，咪唑鎓类似物的PL带最蓝移（646 nm），吡咯烷鎓对应物的PL带最红移（689 nm）。然而，所研究的次磷酸盐最有趣的性质是光致发光强度强烈的温度依赖性，这表明这些化合物在非接触光学测温中可能有应用。
