Structural Phase Transitions of a Layered Organic–Inorganic Hybrid Compound: Tetra(cyclopentylammonium) Decachlorotricadmate(II), [C₅H₉NH₃]₄Cd₃Cl₁₀

Abstract

A layered organic-inorganic hybrid compound, tetra(cyclopentylammonium) decachlorotricadmate(II) (1), in which the two-dimensional [Cd3Cl10](4-)n networks built up from three face-sharing CdCl6 octahedra are separated by cyclopentylammonium cation bilayers, has been discovered as a new phase transition material. It undergoes two successive structural phase transitions, at 197.3 and 321.6 K, which were confirmed by differential scanning calorimetry measurements, variable-temperature structural analyses, and dielectric measurements. The crystal structures of 1 determined at 93, 298, and 343 K are solved in P2₁2₁2₁, Pbca, and Cmca, respectively. A precise analysis of the structural differences between these three structures reveals that the origin of the phase transition at 197.3 K is ascribed to the order-disorder transition of the cyclopentylammonium cations, while the phase transition at 321.6 K originates from the distortion of the two-dimensional [Cd3Cl10](4-)n network.

An amphidynamic inorganic–organic hybrid crystal of bromoplumbate with 1,5-bis(1-methylimidazolium)pentane exhibiting multi-functionality of a dielectric anomaly and temperature-dependent dual band emissions

“…In the context of multifunctional materials, we have targeted the dielectric and fluorescent ones based on haloplumbate hybrids because they have versatile structures in one-to three-dimensions, [18][19][20][21] tunable band gaps 22,23 and a novel fluorescence nature. 24 In addition, it is noted that a haloplumbatebased amphidynamic crystal with anisotropic molecular order and controllable dynamics 25,26 is achievable if the building blocks with volume-conserving motion (dynamic disorder) are introduced into the haloplumbate hybrid lattice, since the disorder-to-order structural transformation frequently occurs in an amphidynamic crystal, this is widely believed to be coupled to dielectric anomalies, [27][28][29][30][31][32][33] such a haloplumbate-based amphidynamic crystal probably displays novel dielectric and fluorescence properties simultaneously.…”

Melting Transitions of the Organic Subphase in Layered Two-Dimensional Halide Perovskites

“…20 In other low-dimensional perovskite-type materials in which an orthorhombic roomtemperature phase also exists, a variety of novel transitions that are unique to the 2D material have been observed. 32,35 In particular, structural deformations of the octahedral layer induced by changes to the packing geometry of the large organic cations separating these layersstrongly affect the energy, lifetime, and localization of the band-edge exciton. 31,36−43 In addition, melting transitions within the organic subphase of perovskite-like alkylammonium lead iodides (noted here as n = 1 2D LHPs) have been previously identified.…”

“…Like their bulk counterparts, 2D lead halide perovskites (2D LHPs) also exhibit a range of complicated temperature-dependent structural behavior. − 2D LHPs of the Ruddlesden–Popper type usually exist in orthorhombic crystal structures at room temperature . In other low-dimensional perovskite-type materials in which an orthorhombic room-temperature phase also exists, a variety of novel transitions that are unique to the 2D material have been observed. , In particular, structural deformations of the octahedral layerinduced by changes to the packing geometry of the large organic cations separating these layersstrongly affect the energy, lifetime, and localization of the band-edge exciton. ,− In addition, melting transitions within the organic subphase of perovskite-like alkylammonium lead iodides (noted here as n = 1 2D LHPs) have been previously identified. ,, These melting transitions are understood as order–disorder transformations confined to the organic sublayer and serve to emphasize the hybrid nature of 2D layered perovskite-like materials. The transformations are typically characterized by tilting of the organic chains, contraction of the unit cell, and a discontinuous release of latent heat, as is also observed for other 2D molecular systems such as Langmuir–Blodgett films and self-assembled monolayers (SAMs) on metal surfaces. − …”

A three-dimensional anionic metal–dicyanamide network in poly[ethyltriphenylphosphonium [tri-μ2-dicyanamidato-cadmium(II)]]

“…, is based mainly on their potential applications in molecular dielectrics and ferroelectrics (Zhang et al, 2013;Du et al, 2014). The variable-temperature dielectric response, especially in the relatively high frequency range, is treated as an effective indicator of a structural phase transition (Ye et al, 2011;Fu et al, 2011;Shi et al, 2014;Liao, Mei et al, 2014;. However, we were unable to detect any dielectric anomalies for (I) over the frequency range of 10 to 1 MHz and in the temperature range from 103 to 453 K, suggesting that there are no structural phase transitions during the cooling and heating processes.…”