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

Abstract

Two new organic–inorganic hybrid molecular single crystals, 4-Iodoanilinium perchlorate 18-crown-6 (1) and 4-Iodoanilinium borofluorate 18-crown-6 (2), with large sizes and high thermal stability were successfully synthesized by solution method. Their structures, phase purities, thermal stability, dielectric, absorption and fluorescence spectra were systematically investigated for potential applications. Compounds 1 and 2 crystallize in orthorhombic crystal system, in same space group, namely Pnma. The thermal measurements shown 1 and 2 maintain high thermal stability up to 150 °C. The temperature dependency of dielectric constant was studied, and no distinct anomaly was observed. The band gap were calculated to be 3.38 eV and 3.57 eV for 1 and 2, respectively, slightly smaller than those of layer perovskite (benzylammonium)2PbCl4 semiconducting materials, which have potential applications in optoelectronic detection field. The investigations throw light on the semiconductor properties of organic–inorganic hybrid crown type material and provide two types of crown compounds with high thermal stability.

Thick Hydride Vapor Phase Heteroepitaxy: A Novel Approach to Growth of Nonlinear Optical Materials

“…Often the latter is due to absorption provoked by the vibration of the unbalanced molecule of the organic, which can be balanced by introducing heavy ions within the organic molecule [119]. An example of successful molecular engineering is the organic-inorganic crystals [120], which can survive higher temperatures and possess improved IR transparency [121].…”

2-Chloroethylamine·trifluoromethanesulfonate combined with 18-crown-6: a ferroelectric with excellent dielectric switching properties

“…13–16 Crown ethers do not coordinate with anions, so they can react quickly with free anions. 17,18 Different weak intermolecular interactions, such as hydrogen bonding, metal–ligand coordination, charge transfer, and hydrophobic–hydrophilic interactions, can be used to build supramolecular structures within crown ether crystals. 19,20 In particular, 18-crown ether-6-based inclusions are often used as a platform for the construction of molecular ferroelectric and piezoelectric materials, as the host–guest inclusions may have ordered–disordered phase transitions.…”

Two noncentrosymmetric new crystals with high phase transition temperatures: [(parachloroanilinum+)(18-crown-6)][ClO4 −](CH3COCH3) and [(parachloroanilinum+)(18-crown-6)][BF4 −](CH3COCH3)

“…2, the observed endothermic peak in the DSC results clearly reveals a phase transition occurring at 71 °C for both compounds 1 and 2. In contrast, no structural phase transition (or heat anomaly) was found before the melting points (⩾150 °C) 26) of their analogs [(paraiodoanilinium…”

“…[17][18][19][20][21] To date, a large number of organic-inorganic hybrid crown compounds have been prepared and investigated, which display various unique properties as well as different phase transition temperatures. [17][18][19][20][21][22][23][24][25][26][27] [(4-methoxyanilinium)(18-crown-6)]ClO 4 demonstrates ferroelectric properties after a disorder-order structural phase transition which occurs at 153 K. 17) ([C 7 H 10 NO-(18-crown-6)][BF 4 ] presents a second-order ferroelectric phase transition at 127 K. 18) [(DIPA) (18-crown-6)] (ClO 4 ) undergoes a paraelectric-to-ferroelectric transition (centrosymmetric-to-polar phase) at a temperature of 132 K. 19) [(DIPA) (18-crown-6)]BF 4 (DIPA = 2,6-diisopropylanilinium) displays ferroelectric properties after a phase transition temperature of 120 K. 20) Bis(imidazolium hydrochlorate) dihydrate 18crown-6 presents nonlinear optical properties with a phase transition occurring at 220 K. 21) Centrosymmetric (4-HNA) (18-crown-6)(HSO 4 ) and (4-HNA) 2 (18-crown-6) 2 (PF6) 2 (CH 3 OH) (4-HNA = 4-nitroanilinium) undergo two reversible phase transitions at about 255 K and 265 K, respectively. 22) Centrosymmetric [(3-nitroanilinium)(18-crown-6)][IO 4 ] (CH 3 OH) undergoes a reversible phase transition at around 220 K. 23) [Hcha- (18-crown-6)][BF 4 ] and [Hcha- (18-crown-6)] [ClO 4 ] (Hcha = protonated cyclohexyl ammonium) exhibit ferroelectric phase transitions at about 397 and 390 K, respectively.…”

“…Their analogs [(paraiodoanilinum + )(18-crown-6)][ClO 4 − ]/[BF 4 − ] crystallize in Pnma and thus demonstrate centrosymmetric structures. 26) Therefore, the acetones were supposed to be the inducements to bring about the noncentrosymmetric structures of 1 and 2. Crystals with noncentrosymmetric structures demonstrate piezoelectric properties based on our knowledge of crystal physics; thus, it is regarded that the acetones in the structures introduced piezoelectric properties.…”