Inorganic Anions Regulate the Phase Transition in Two Organic Cation Salts Containing [(4-Nitroanilinium)(18-crown-6)]+ Supramolecules

Abstract

Two novel inorganic-organic hybrid supramolecular assemblies, namely, (4-HNA) (18-crown-6)(HSO 4 ) (1) and (4-HNA) 2 (18-crown-6) 2 (PF 6 ) 2 (CH 3 OH) (2) (4-HNA = 4-nitroanilinium), were synthesized and characterized by infrared spectroscopy, single X-ray diffraction, differential scanning calorimetry (DSC), and temperature-dependent dielectric measurements. The two compounds underwent reversible phase transitions at about 255 K and 265 K, respectively. These phase transitions were revealed and confirmed by the thermal anomalies in DSC measurements and abrupt dielectric anomalies during heating. The phase transition may have originated from the [(4-HNA)(18-crown-6)] + supramolecular cation. The inorganic anions tuned the crystal packings, and thus influenced the phase-transition points and types. The variable-temperature X-ray diffraction data for crystal 1 revealed the occurrence of a phase transition in the high-temperature phase with the space group of P2 1 /c and in the low-temperature phase with the space group of P2 1 /n. Crystal 2 exhibited the same space group P2 1 /c at different temperatures. The results indicated that crystals 1 and 2 both underwent an iso-structural phase transition.

Above Room Temperature Reversible Phase Transition Induces Distinct Dielectric and Nonlinear Optical Switching Response Behavior in Crown-Ether-Based Supramolecular Clathrate

“…Recently, a great deal of effort in this field has been devoted to the design of molecule-based materials with multiple switching effects of physical properties for potential application in the fields of digital processing, optoelectronic devices, and sensors [6][7][8]. Among them, crown-ether-based rotator-stator-type supramolecular compounds have shown advantages in realization of such effects [9][10][11][12][13]. This is due to the structural characteristics of the supramolecular compounds, where the dipolar rotator molecules easily undergo the order-disorder change, leading to rich structural phase transitions accompanied by ferroelectric, dielectric, and nonlinear optical (NLO) switching, as exemplified by [(C 7 H 10 NO) (18- [4,[14][15][16][17].…”

Growth and Property Investigations of Two Organic–Inorganic Hybrid Molecular Crystals with High Thermal Stability: 4-Iodoanilinium perchlorate 18-crown-6 and 4-Iodoanilinium Borofluorate 18-crown-6

“…(2,6-diisopropylanilinium)([18]crown-6)](ClO4) [26] T1=278 T2=132 Ferroelectric Ps=0.35 μC/cm 2 (4-nitroanilinium)2(18-crown-6)2(PF6)2(CH3OH) [29] 265 -----(4-nitroanilinium)(18-crown-6)(HSO4 [29] 255 -----Bis(imidazolium hydrochlorate) dehydrate 18-crown-6 [28] 220…”

“…For example, the ferroelectric property was observed in 4-methoxyanilinium perrhenate 18-crown-6 [25] but was not detected in 4-ethoxyanilinium perchlorate 18-crown-6present [32], although the difference (methoxyl or ethyoxyl) of the two amine derivatives is very small. Ferroelectric P s = 0.35 µC/cm 2 (4-nitroanilinium) 2 (18-crown-6) 2 (PF6) 2 (CH3OH) [29] 265 -----(4-nitroanilinium)(18-crown-6)(HSO 4 [29] 255 -----Bis(imidazolium hydrochlorate) dehydrate 18-crown-6 [28] 220…”

“…A large number of crown type molecular materials have been synthesized in the recent decades [23][24][25][26][27][28][29][30][31][32][33][34]. For example, 4-methoxyanilinium tetrafluoroborate-18-crown-6 shows a second-order ferroelectric phase transition at 127 K, together with an abrupt dielectric anomaly, Debye-type relaxation behaviour [24].…”

“…Bis(imidazolium hydrochlorate) dehydrate 18-crown-6 displays attractive switching performances with a superior second-order nonlinear optical switching contrast (calculated by Landau theory) of 12 at about 0 K, and a phase transition occurred at 220 K [28]. (4-HNA)(18-crown-6)(HSO 4 ) underwent phase transition at about 255 K with space group of P2 1 /c in the high-temperature phase and P2 1 /n in the low-temperature phase [29]. [(3-nitroanilinium+)(18-crown-6)][IO 4 ](CH 3 OH) was discovered displaying dielectric anomalous behaviors at phase temperature of 220 K, with space group of C2/c both before and after phase transition [30].…”