Wydział Chemii

Klaudia Mencel

Przemysław Starynowicz

Miłosz Siczek

Anna Piecha-Bisiorek

Ryszard Jakubas

Wojciech Medycki

2019

Dalton Transactions

48

14829-14838

10.1039/c9dt02916h

Naukowa

Angielski

Artykuł

Two organic–inorganic hybrid halobismuthates(III), (NH₂CHNH₂)₃[Bi₂Cl₉] (FBC) and (NH₂CHNH₂)₃[Bi₂Br₉] (FBB), have been prepared with their structures revealed by single-crystal X-ray diffraction at various temperatures. FBC is characterized by one-dimensional (1D) [Bi₂Cl₉]³⁻_∞ anionic chains built by edge-sharing BiCl₆ octahedra, whereas FBB adopts a layer structure (2D) [Bi₂Br₉]³⁻_∞. Both materials were found to exhibit a rich polymorphism in the solid state. FBC undergoes two reversible phase transitions (PTs) at 218/220 K and at 123/126 K (cooling/heating), respectively, whereas for FBB also two PTs occur close together at 196/199 K and at 190/188 K. Dielectric response around the PT temperatures of FBC and FBB reflects high disorder of dipolar groups over the high temperature phases. The ‘order–disorder’ mechanism of these PTs is assigned to the dynamics of formamidinium cations. FBB is considered as a ferroic material exhibiting ferroelastic domains below 196 K. The molecular motions of organic cations in a wide temperature range were studied by means of ¹H NMR (spin–lattice relaxation time). Presented findings will provide a new method to explore organic−inorganic multifunctional PT materials.

http://dx.doi.org/10.1039/c9dt02916h

https://www.rsc.org/