Subtly tuning intermolecular hydrogen bonds in hybrid crystals to achieve ultrahigh-temperature molecular ferroelastic

Abstract

Molecule-based ferroic phase-transition materials attracted increasing attentions in the past decades due to their promising potentials as sensors, switches, and memories. One of long-term challenges in the development of molecule-based...

An anomalous ferroelastic phase transition arising from an unusualcis-/anti-conformational reversal of polar organic cations

“…Based on the cell parameters of 1 and 2 at 314 K and 340 K deduced by extrapolating the fitting lines of variable-temperature cell parameters, the total spontaneous strains were estimated as 0.059 and 0.062 for 1 and 2 , respectively (for details, see ESI†). 32,42 These spontaneous strain values are of intermediate level for other hybrid ferroelastics, 15–29 but the value for 2 (0.062) was much larger than those observed in the documented anomalous ferroelastics with inverse symmetry breaking, such as [Zn(saloph)] 2 (μ-dabco) (0.02), 36 (Me 3 NCH 2 CH 2 OH) 4 [Ni(NCS) 6 ] (0.0073), 37 and (Et 4 N)(Me 4 N)[MnBr 4 ] (0.0043). 43,44 These results implied that the anomalous ferroelastic transition and large spontaneous strain in 2 should be strongly associated with not only the order-disorder dynamic transition of cations but also the cis -/ anti -conformational variations in organic cations.…”

“…, between a ferroelastic LTP and a paraelastic HTP, which is similar to the behaviors of most known ferroelastic materials. 17–29 In contrast, in the temperature range of 300–380 K for 2 , no multi-domain structure was observed at 303 K as it was in its paraelastic phase ( 2_LTP ). Upon further heating to 380 K ( 2_HTP ), the theoretically-predicted multiple domains with two anti-parallel orientation states could be clearly distinguished, which then completely disappeared after cooling back to 300 K. Therefore, as compared to 1 and most other ferroelastic materials, 2 is a rare ferroelastic material with a ferroelastic phase at HTP rather than at LTP.…”

“…9,10 Hybrid ferroelastics, as important supplements, could be assembled in solutions under moderate conditions from diverse organic and inorganic components, hence offering an eco-friendly and feasible approach for designing ferroelastic materials. 11–14 Recent years have witnessed the emergence of numerous hybrid ferroelastics, 15–27 such as (Me 3 NOH) 2 [ZnCl 4 ] with a large spontaneous strain of 0.129, 28 (nortropinium)[CdCl 3 ] with the ultrahigh ferroelastic phase-transition temperatures of 463 and 495 K, 29 and the chiral ( R -3-chloro-2-hydroxypropyltrimethylammonium) 2 CuCl 4 with seven physical channel switches. 30…”

Tin-based organic–inorganic metal halides with a reversible phase transition and thermochromic response

“…[11][12][13] At the same time, dielectric phase transition (thermally stimulated response) materials often bring about interesting physical properties such as fluorescence, [14][15][16] thermochromism, [17][18][19][20] ferroelectricity [21][22][23] and so on. [24][25][26][27][28][29][30] Compared with high-dimensional hybrid phase transition materials with limited organic ammonium species, the structures of low-dimensional compounds are more flexible and diverse. [31][32][33][34] Meanwhile, low-dimensional materials can provide a large degree of freedom for organic ammonium, thereby triggering the order-disorder phase transition.…”

Methyl regulation triggers high-temperature ferroelastic phase transition

“…Recently, the report of a three-dimensional cyano-bridged double perovskite ferroelastic [(CH 3 ) 3 NCH 2 F] 2 [KFe(CN) 6 ] has shown a phase transition from the ferroelastic phase C 2/ c to the paraelastic phase Fm 3̄ m space group at 253 K. 44 The Chen group fine-tuned intermolecular hydrogen bonds in hybridized crystals to achieve ultra-high temperature molecular iron elastomers (nortropinonium) [CdCl 3 ]. 45 And our group successfully obtained ferroelastic (Me-Hdabco) Rb[BF 4 ] 3 by hydrogen-bonded engineering and has significantly increased the phase transition temperature compared to the original material. 46 These studies suggest that molecular fine design strategies will unsurprisingly be a sure approach for material performance enhancement.…”