S1
Supporting Information
Record Enhancement of Curie Temperature in Host-Guest Inclusion
Ferroelectrics
Xian-Jiang Song, Tie Zhang, Zhu-Xiao Gu, Zhi-Xu Zhang, Da-Wei Fu,* Xiao-Gang Chen, Han-Yue Zhang, and Ren-Gen Xiong*
Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics, Southeast University, Nanjing 211189, People’s Republic of China
Experiments and characterization methods
Material synthesis and crystal growth. All reagents and solvents in this experiment were of reagent
grade and used without further purification. Equimolar 4-methoxyaniline, 18-crown-6 and bis(trifluoromethanesulfonyl)amine were dissolved in methanol solution. The block-like crystals of [(MeO-C6H4-NH3)(18-crown-6)][TFSA] were easily obtained by slow evaporation of the resulting
clear methanol solution.
Thin-film preparation. The crystals of [(MeO-C6H4-NH3)(18-crown-6)][TFSA] were dissolved in
dimethyl sulfoxide (DMSO) to form a precursor solution with 500 mg/mL.
Spin-coating method. The thin film was prepared by spin-coating (2000 rpm, 30 s) the precursor solution (20 μL) onto ITO (indium tin oxide) glass substrate and annealing with 343 K for 30 min. This thin film was used for PFM measurements.
Drop-casting method. 20 μL of precursor solution was spread on a clean ITO-coated glass (1 × 1 cm2).
The thin film was obtained after evaporating the solution at 343 K for 30 min. This thin film was used for P–E hysteresis loop and PFM measurements.
Single-crystal X-ray crystallography. Single-crystal X-ray diffraction data were measured using a
Rigaku VarimaxTM DW diffractometer with Mo-Kα radiation (λ = 0.71073 Å). The structures were solved by direct methods and refined by the full-matrix method based on F2 using the SHELXTL
software package. All non-hydrogen atoms were refined anisotropically and the positions of all hydrogen atoms were generated geometrically. The data collection and structure refinement of these crystals are summarized in Table S1. The X-ray crystallographic structures have been deposited at the Cambridge Crystallographic Data Centre (deposition numbers CCDC: 2053454, 2053455 and 2064501) and can be obtained free of charge from the CCDC via www.ccdc.cam.ac.uk/getstructures.
S2
Powder X-ray diffraction. Powder X-ray diffraction (PXRD) data were measured using a Rigaku
D/MAX 2000 PC X-ray diffraction system with Cu Kα radiation in the 2θ range of 5°–50° with a step size of 0.02° and a scan rate of 10°/min.
DSC and SHG measurements. Differential scanning calorimetry (DSC) measurements were
recorded on a NETZSCH DSC 200F3 instrument by heating and cooling crystalline samples with a rate of 20 K min−1 under in aluminum crucibles at nitrogen atmosphere. SHG measurements were carried out on FLS 920, Edinburgh Instruments using an unexpanded laser beam with low divergence (pulsed Nd: YAG at a wavelength of 1064 nm). The laser is Vibrant 355 II, OPOTEK.
Hirshfeld surfaces analysis. Hirshfeld surfaces and the related 2D-fingerprint plots were calculated
by using the CrystalExplorer program with inputting structure file in CIF format. The CIF of [(MeO-C6H4-NH3)(18-crown-6)][BF4] was obtained from the previous work (J. Am. Chem. Soc. 2011, 133,
12780-12786). In this work, all the Hirshfeld surfaces were generated using a standard (high) surface resolution. The 3D Hirshfeld surfaces and 2D fingerprint plots are unique for any crystal structure. The intensity of molecular interaction is mapped onto the Hirshfeld surface by using the respective red-blue-white scheme: where the white or green regions exactly correspond to the distance of Van der Waals contact, the blue regions correspond to longer contacts, and the red regions represent closer contacts. In 2D fingerprint plots, each point represents an individual pair (di, de), reflecting the
distances to the nearest atom inside (di) and outside (de) of the Hirshfeld dnorm surface.
The normalized contact distance dnorm is based on de, di and the van der Waals (vdW) radii of the two
atoms external (revdW) and internal (rivdW) to the surface:
dnorm = 𝑑𝑖 − 𝑟
𝑣𝑑𝑊
𝑟𝑖𝑣𝑑𝑊 + 𝑑𝑒− 𝑟
𝑟𝑒𝑣𝑑𝑊
dnorm surface is used for the identification of close intermolecular interactions.
NMR measurements and Mass Spectrometry. We have checked the 1H NMR, 13C NMR, and 19F NMR measurements of the supramolecular species with a 300 MHz Bruker spectrometer in CD3OD
solvent (Chemical shifts are reported in parts per million (ppm) down field from TMS with the solvent resonance as the internal standard) (Figures S11-S14). The 1H NMR data of 18-crown-6, 1H NMR data of p-anisidine, and 13C NMR data of bis(trifluoromethanesulfonyl)imide were also measured in order to compare with that of the supramolecular species. As shown in the 1H NMR data of the supramolecular species, there are 4 aromatic protons, a single peak with 3 protons of -OCH3, and a
single peak with 24 protons of 18-crown-6 (Figure S11). The chemical shifts of the protons in -OCH3
and aromatic protons showed large shifts to the low field region in comparison to those of p-anisidine. The reason is that the electro-donating -NH2 group formed into electro-withdrawing -NH3+ group in
S3 shifted in comparison to that of 18-crown-6 individually due to the hydrogen-bond formation between 18-crown-6 and -NH3+ in the supramolecular species, forming a large complex [(MeO-C6H4-NH3
)(18-crown-6)]+ cation (Figure S11). The 13C NMR data of the supramolecular species in the aromatic
region contains 6 carbon peaks, indicating that there are 4 kinds of carbons from the phenyl ring and 2 carbon peaks from the -CF3 whose carbon split due to the CF coupling (Figure S13). The 19F NMR
data of the supramolecular species also indicated that it contains the (CF3SO2)2N- moiety in the
supramolecular species (Figure S14). In conclusion, the NMR data illustrated the existence of complex [(MeO-C6H4-NH3)(18-crown-6)]+ cation and (CF3SO2)2N- (TFSA) anion in the supramolecular
species. To further confirm the existence of large complex cations, we also measured the mass spectrum (by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry). The results show that the fragment ion peak (m/z = 388) corresponds to the complex [(MeO-C6H4-NH3
)(18-crown-6)]+ cation (Figure S15). The NMR data and mass spectrum strongly confirm the existence of the supramolecular species in solution.
S4
Figure S1. Comparison of the interactions and surrounding environments of (a) [BF4]- anion in
[(MeO-C6H4-NH3)(18-crown-6)][BF4] and (b) [TFSA]- anion in [(MeO-C6H4-NH3)(18-crown-6)][TFSA].
Figure S2. Packing view of crystal structure of [(MeO-C6H4-NH3)(18-crown-6)][TFSA] along a-axis
S5
Figure S3. DSC curves of [(MeO-C6H4-NH3)(18-crown-6)][TFSA].
Figure S4. Crystal structures of [(MeO-C6H4-NH3)(18-crown-6)][TFSA] at 93 K in LTP. (a) The basic
structure. (b) Packing view of structure. Parts of hydrogen atoms were omitted for clarity.
At 93 K (in low temperature phase, LTP), [(MeO-C6H4-NH3)(18-crown-6)][TFSA] crystallizes in
monoclinic space group P21 with cell parameters of a = 8.2158(5) Å, b = 16.3714(10) Å, c = 10.9944(9)
Å, and β = 91.027(6)° (Table S1). The basic unit of structure is similar to those in RTP and ITP. Structurally, the 18-crown-6 molecules, guest (MeO-C6H4-NH3)+ cations and counterpart TFSA anions
show completely ordered state (Figure S4).
NOTE: For the single-crystal structures in LTP, RTP and ITP, the Rint values are low as 0.0690, 0.0442,
0.0488 respectively, suggesting the good crystal structural data. In LTP, the structure of [(MeO-C6H4
-NH3)(18-crown-6)][TFSA] shows a well ordered state with low R1 and wR2 values. As the temperature
rises into RTP and ITP, thermal ellipsoids of all atoms become larger, and the thermal vibrations of atoms become more intense, which leads to large R-factors (R1 and wR2 values).
S6
Figure S5. Molecular structures of [(MeO-C6H4-NH3)(18-crown-6)][TFSA] at 93 K (in LTP), 283 K
(in RTP) and 333 K (in ITP), respectively. Thermal ellipsoids for all atoms are shown at the 30% probability level. H atoms were omitted for clarity.
Figure S6. The measured PXRD patterns of [(MeO-C6H4-NH3)(18-crown-6)][TFSA] in (a) RTP and
S7
Figure S7. Variable-temperature PXRD patterns of [(MeO-C6H4-NH3)(18-crown-6)][TFSA] from
S8
Figure S8. Structural refinement results of PXRD data for [(MeO-C6H4-NH3)(18-crown-6)][TFSA] in
HTP. The indexing of PXRD data reveals an orthorhombic lattice, and through the Pawley refinements, we obtained the orthorhombic point group mmm, among which the most possible space group is Pcca. The refined cell parameters are a = 16.4959 Å, b = 11.1363 Å, c = 11.9287 Å. These results are highly consistent, confirming the phase purity of the compound and high accuracy of the simulation methods.
S9
Figure S9. Hirshfeld dnorm surfaces of (a) TFSA anion and (b) 18-crown-6 molecule in [(MeO-C6H4
-NH3)(18-crown-6)][TFSA], and (c) [BF4]- anion and (d) 18-crown-6 molecule in [(MeO-C6H4
-NH3)(18-crown-6)][BF4], respectively. 2D fingerprint plots of (e) TFSA anion and (f) 18-crown-6
molecule in [(MeO-C6H4-NH3)(18-crown-6)][TFSA], and (g) [BF4]- anion and (h) 18-crown-6
S10
Figure S10. The domain structure detected in a thin film of [(MeO-C6H4-NH3)(18-crown-6)][TFSA]
S11
Figure S11. Comparison of the 1H NMR data of 18-crown-6, p-anisidine and the supramolecular species.
S12
Figure S13. The 13C NMR data of the supramolecular species.
S13
S14
Table S1. Crystal data and structure refinement for [(MeO-C6H4-NH3)(18-crown-6)][TFSA] at
99 K, 283 K and 333 K, respectively.
Compound [(MeO-C6H4-NH3)(18-crown-6)][TFSA]
Formula C12H24O6·C2F6NO4S2·C7H10NO
Temperature 93 K 283 K 333 K
Weight 668.62 668.62 668.62
Crystal system Monoclinic Monoclinic Monoclinic
Space group P21 Pc Pc a (Å) b (Å) c (Å) 8.2158(5) 16.3714(10) 10.9944(9) 11.092(2) 8.4140(13) 16.627(3) 11.229 (2) 8.440 (2) 16.649 (4) β (o) 91.027(6) 93.965 90.30 V (Å3) 1478.55(18) 1548.0 (5) 1577.9 (6) Z 2 2 2 Rint 0.0690 0.0442 0.0488 R1 0.1208 0.2824 0.2664 wR2 0.3339 0.6496 0.6010 GOF 1.089 1.433 1.742
Table S2. Hydrogen bonds for [(MeO-C6H4-NH3)(18-crown-6)][TFSA] in RTP and ITP,
respectively.
D—H···A D—H H···A D···A
RTP N2—H2A···O7 0.89 2.007 2.516 (13) N2—H2A···O6 0.89 1.650 2.463 (14) N2—H2B···O8 0.89 1.910 2.778 (13) N2—H2B···O9 0.89 2.346 2.903 (14) N2—H2C···O10 0.89 2.160 2.980 (13) N2—H2C···O11 0.89 1.955 2.655 (13) C9—H9B···O2 0.96 2.627 3.539 (23) ITP N2—H2A···O8 0.89 1.711 2.600 (38) N2—H2B···O6 0.89 1.896 2.750 (55) N2—H2C···O10 0.89 2.009 2.879 (53) C9—H9B···O2 0.96 3.038 3.762 (86)
