A Crystalline Supramolecular Rotor Functioned by Dual Ultrasmall Polar Rotators^†

Abstract

Comprehensive Summary As an extended model of conventional molecular rotors, a conceived construction of novel crystalline molecular rotor that simultaneously contains two discrete polar rotators is presented here. The supramolecular self‐assembly of 18‐crown‐6 host and two rotator‐containing ion‐pair guests affords a three‐in‐one cocrystal, (2‐NH3‐iBuOH)(18‐crown‐6)[ZnBr3(H2O)], in which the hydroxyl group and aqua ligand both function as ultrasmall polar rotators. On the basis of the variable‐temperature single‐crystal X‐ray diffraction, variable‐temperature/frequency dielectric response, density functional theory calculations, and molecular dynamics simulations, it is found that such dual polar rotators experience a gradually enhanced rotation with increasing temperature, and more importantly, could be controlled by a reversible polar‐to‐polar structural phase transition, i.e., from a “single‐(polar rotator)” state at low‐temperature phase to a “mixed‐dual‐(polar rotator)” state in the vicinity of transition, and to an unusual “synchronized‐dual‐(polar rotator)” state at high‐temperature phase.

Remarkable enhancement of optical and electric properties by temperature-controlled solid-phase molecular motion

“…19,31,32 Fortunately, crown-ether-based supramolecules with the advantages of structural diversity and chemical variability, not only a variety of crown ethers, organic cations and counterions are available, but also some efficient molecular modification strategies can also be employed. 16,17,19,21,33 The first case of crown-ether-based molecular rotator with a polar structure, [( m -FAni)(DB-18-crown-6)][Ni(dmit) 2 ] ( m -FAni = m -fluoroanilinium, DB = dibenzo, dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate), which was reported by Akutagawa et al in 2009, was obtained by modifying the organic cation and replacing the crown ether of [(anilinium)(18-crown-6)][Ni(dmit) 2 ] with bulky DB-18-crown-6. 8 In addition, based on H/F substitution of the organic cation of the prototype [(CH 3 –C 6 H 4 –NH 3 )(18-crown-6)][TFSA] (CF 3 –C 6 H 4 –NH 3 = 4-trifluoromethylanilinium), Lv et al discovered a crown-ether-based polar molecular rotator [(CF 3 –C 6 H 4 –NH 3 )(18-crown-6)][TFSA] with a remarkable piezoelectric response.…”

“…12,15,16 This type of molecular rotator is assembled and packed by weaker intermolecular interactions (such as hydrogen bonds, van der Waals bonds and electrostatic force) and therefore, it is conducive to the dynamic motion of the building blocks under external stimuli, which may further lead to significant changes in molecular microstructure and macroscopic physical characteristics. [17][18][19][20] Notably, based on this characteristic, many molecular rotators, such as [Co(NCS) 2 (H 2 O) 2 (4-amino-3-chloropyridine) 2 ](18crown-6), 18 [(MeO-C 6 H 4 -NH 3 )(18-crown-6)](TFSA) (MeO-C 6 H 4 -NH 3 = 4-methoxyanilinium, TFSA = bis(trifluoromethanesulfonyl)ammonium), 19 [(2,2,6,6-tetramethylpiperidine-N-oxyl)(18crown-6)]ReO 4 /ClO 4 , 21 [(2,6-diisopropylanilinium)(18-crown-6)] ClO 4 , 22 (MeO-C 6 H 4 -NH 3 )(18-crown-6)ReO 4 , 23 [(MeO-C 6 H 4 -NH 3 )(18-crown-6)][BF 4 ], 24 have so far been studied and reported for promising applications in intelligent switches, sensors, memorizers, transducers, and so on.…”

“…19,31,32 Fortunately, crown-ether-based supramolecules with the advantages of structural diversity and chemical variability, not only a variety of crown ethers, organic cations and counterions are available, but also some efficient molecular modification strategies can also be employed. 16,17,19,21,33 The first case of crown-ether-based molecular rotator with a polar structure, ] with bulky DB-18crown-6. 8 In addition, based on H/F substitution of the organic cation of the prototype…”

Effect of Pd(ii) uptake on high-temperature phase transitions in a hybrid organic–inorganic perovskite semiconductor

“…1–10 As crystalline materials derived from organic and inorganic components, HOIPs have been extensively investigated for their fascinating and intriguing properties and functionalities. 11–22 Among them, perovskite-type hybrids with the general chemical formula ABX 3 (A = organic cation, B = divalent metal and X = anion) have drawn increasing attention due to their excellent physical properties and practical applications in structural phase transitions, electricity, magnetism, luminescence and solar cells. 23–29 According to previous studies, hybrid organic–inorganic ABX 3 perovskites can be crystallized in two structural forms, one adopts the same structure as the inorganic ABX 3 perovskite CaTiO 3 , including a three-dimensional BX 3 framework with corner-sharing octahedra, where B = Pb( ii ), Sn( ii ), X = halide and A = methylammonium, 30,31 formamidinium, 32 methylhydrazinium 33,34 and aziridinium.…”

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

“…To demonstrate this design principle through subtle molecular design, as one of our ongoing studies on multi-component hybrid crystals based on hydroxyl-containing polar cations, 22,33–36 herein we present two nice examples of hexagonal perovskites (Scheme 2), (Hnto)[CdCl 3 ] ( 1 , Hnto + = nortropinonium) and (Hntp)[CdCl 3 ] ( 2 , Hntp + = nortropinium). They consist of the same inorganic components but different organic cations featuring a rigid carbonyl group in 1 and a flexible hydroxyl group in 2 .…”