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Two‐dimensional (2D) hybrid perovskites have shown many attractive properties associated with their soft lattices and multiple quantum well structure. Herein, we report the synthesis and characterization of two new multifunctional 2D hybrid perovskites, (PED)CuCl4 and (BED)2CuCl6, which show reversible thermochromic behavior, dramatic temperature‐dependent conductivity change, and strong ferromagnetism. Upon temperature change, the (PED)CuCl4 and (BED)2CuCl6 crystals exhibit a reversible color change between yellow and red‐brown. The associated structural changes were monitored by in situ temperature‐dependent powder X‐ray diffraction (PXRD). The (BED)2CuCl6 exhibits superior thermal stability, with a thermochromic working temperature up to 443 K. The conductivity of (BED)2CuCl6 changes over six orders of magnitude upon temperature change. The 2D perovskites exhibit ferromagnetic properties with Curie temperatures around 13 K.

The structure, phase transition, and nucleation of Au nanoparticles confined within armchair single-walled carbon nanotubes ((n,n)-SWNTs) are investigated using molecular dynamics (MD) simulation technique. The Au−Au interactions are described by the TB-SMA potentials and the Au-SWNT interactions are represented by Lennard-Jones potential. SWNTs are approximately considered to be rigid. The total energies, structures, Lindemman indices, and radial density distributions are used to reveal the feature of phase transition for Au nanoparticles confined in (n,n)-SWNTs. The classical nucleation theory is applied to perform nucleation analysis. Results demonstrate that confined Au N exhibit multishell structures. The order−disorder transformation of atoms in each layer is an important structure feature of phase transition. Interestingly, the melting starts from the innermost layer and freezing starts from outermost layer for confined Au nanoparticles. SWNTs have a significant effect on the structures and stabilities of the confined Au nanoparticles. On the other hand, some important thermodynamic and dynamic parameters are estimated and compared with available experimental and calculated results. This work provides the primary physical insights into the phase transition and nucleation process of confined Au nanoparticles.

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