Self-Assembly of Amphiphilic Schiff Base and Selectively Turn on

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Interface-Rich Materials and Assemblies

Self-Assembly of Amphiphilic Schiff Base and Selectively Turn on Circularly Polarized Luminescence by Al3+ Qingxian Jin, Shuyu Chen, Hejin Jiang, Yuan Wang, Li Zhang, and Minghua Liu Langmuir, Just Accepted Manuscript • DOI: 10.1021/acs.langmuir.8b03019 • Publication Date (Web): 06 Nov 2018 Downloaded from http://pubs.acs.org on November 8, 2018

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Self-Assembly of Amphiphilic Schiff Base and Selectively

Turn

on

Circularly

Polarized

Luminescence by Al3+ Qingxian Jin,a Shuyu Chen,a,b Hejin Jiang,b Yuan Wang, b Li Zhang,*b Minghua Liu*b a

Henan Provincial Key Laboratory of Surface & Interface Science, Zhengzhou University of

Light Industry, Zhengzhou, Henan 450002, China. b

Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface

and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT: We designed glutamide-derived amphiphilic Schiff bases containing three different aldehyde moieties for the fabrication of circularly polarized luminescence (CPL) emitting materials. Upon self-assembly in acetonitrile, Schiff bases featuring 4-(dimethylamino)2-hydroxylbenzaldehyde and 1-hydroxy-2-naphthaldehyde groups form supramolecular gels with twist and fiber structures, respectively, while Schiff bases featuring 2-hydroxy-1naphthaldehyde groups forms precipitation with flakes structures. Although emission and circular dichroism (CD) signals can be detected from the supramolecular gels formed by amphiphilic Schiff bases, none of them exhibits circularly polarized luminescence (CPL). While Mg2+, Zn2+ and Al3+ can both significantly enhance the fluorescence of the Schiff bases, interestingly, only Al3+ ion is able to turn on the CPL emission. This study on the one hand

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provides a simple method to the fabrication of CPL emitting supramolecular materials, and on the other hand offers a novel way to the sensing of aluminum ion with supramolecular materials. INTRODUCTION Recently, there has been increasing interest in circularly polarized luminescence (CPL) emitting materials, as on the one hand, CPL provides the valuable information on the chirality of the electronic excited states,1 and on the other hand, CPL emitting materials have potential applications in optical display, asymmetric photochemical synthesis and chiral sensing.2-5 In developing CPL materials, it is necessary that the system has both the chirality and fluorescence or phosphorescence chromophores. In order to couple the chirality and fluorescent emission, a basic idea is to covalently link the chiral units to fluorescence chromophores. However, it usually needs tedious organic synthesis to construct such chiral building blocks. An alternative way is to connect fluorophore to the chiral units through non-covalent bonds. So far, typical CPL emitting materials are π-conjugated organic molecules, 6-9 chiral supramolecular assemblies, 10-12

chiral conjugated polymers

13-16

and so on. Although non-covalent interactions such as

metal-organic coordination have been proved feasible to turn on the fluorescence or phosphorescence of chiral molecules and chiral assemblies, to date only lanthanide coordination compounds have been developed as CPL emitting materials. On the other hand, besides the covalent and non-covalent bonds, the dynamic covalent bonds, recently attracted the researcher interest, either in the synthesis of COF and MOF materials or in the self-assembling systems, since they can be easily tuned. 17-22 Schiff-base is a kind of organic ligand containing an imine bond, which is a dynamic covalent bond and can be easily synthesized.23,24 Moreover, many Schiff bases have strong emission and coordination ability with various of metal ions,25-27 thus could be used as CPL candidate materials. While


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many fluorescent materials containing the Schiff bases and their coordination compounds were extensively investigated, there is no report on the CPL materials. Here, using an amine terminate dialkyl glutamide amphiphile (LG), as shown in Scheme 1, we assembled this chiral amphiphile with various aromatic aldehydes and obtained some new insight into the Schiff bases as CPL materials. We have found that Schiff bases can be formed by refluxing the LG with various aromatic aldehydes to give compounds 1-3, in which compound 1 and 2 could form gels in a certain solvent. In addition, if we mixed the N, N’-bis(octadecyl)-L-glutamic diamide (LG) with the three

aldehydes,

we

can

also

obtain

the

gels

by

using

4-(dimethylamino)-2-

hydroxylbenzaldehyde and 1-hydroxy-2-naphthaldehyde. Upon gel formation, compound 1 selfassembled into twists and 2 exhibited as fibers, while 3, as an isomer of 2, cannot form supramolecular gel. There were no CPL signals even though these Schiff bases emitted light. Upon addition of metal ions such as Mg2+, Zn2+ and Al3+, the emission was enhanced. Interestingly, in the case of Al3+, CPL emission could be detected. Thus, through Schiff bases formation and metal ions complexation we could develop an Al3+ turn-on CPL material.


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Scheme 1. Molecular structures of amino terminate dialkyl glutamide amphiphile (LG), aromatic aldehydes, formed amphiphilic Schiff bases 1-3 and illustration on the self-assembly of amphiphilic Schiff bases and their response to aluminium ion. EXPERIMENTAL Synthesis of compounds 1-3. Synthesis and characterization of N,N’-bis(octadecyl)-Lglutamic diamide (LG) have been reported previously in our group.28 Synthesis of compounds 1-3: first, LG (650 mg, 1.0 mmol) was mixed with 4-(dimethylamino)-2-hydroxylbenzaldehyde (965 mg, 5.0 mmol), 1-hydroxy-2-naphthaldehyde (860 mg, 5.0 mmol) or 2-hydroxy-1naphthaldehyde (860 mg, 5.0 mmol) in 200 mL EtOH and refluxed at 80 ℃ for 8h. After the removal of heating, crude products were obtained by filtration. Recrystallization in EtOH afforded compound 1 (700 mg, 85%), compound 2 (660 mg, 82%) and compound 3 (643 mg, 80%), then all appeared as yellow solids. Enantiomer of compound 2 was obtained by mixing N,N’-bis(octadecyl)-D-glutamic diamide

(DG) with 1-hydroxy-2-naphthaldehyde. 1H NMR

spectra of all the target products are shown in Figure S1-S4. All other materials applied in the


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study were used as received from commercial suppliers. Sample preparations. Self-assembly of the three compounds were investigated in acetonitrile. First, 4 mg of 1, 2 or 3 was dissolved in 500 μL acetonitrile by gentle heating at around 70 ℃ for a few minutes. Then the hot solution was naturally cooled down to room temperature to form

organic gel or precipitate. (Gels formed in acetonitrile with the

concentration of 1×10-2 M for 1 and 2, but precipitation for 3).Al3+-coordinated supramolecular assemblies was obtained by 66.5 mg of AlCl3 dissolved into 100 mL EtOH, and then 500 μL of AlCl3 solution was put into the sample bottle containing 2 mg compound 1, 2 or 3. The mixture was gently heated at around 70°C for a few minutes until a transparent solution appeared, then cooled to room temperature. Other metal ions-coordinated supramolecular compounds were obtained in the same method. Characterizations. 1H NMR and mass spectral data spectra were recorded on a Bruker AV 400 (400 MHz) spectrometer and a BIFLEIII matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) instrument, respectively. All the self-assembled nanostructures were transferred onto silicon wafers and coated with a layer of Pt particles for scanning electron microscopy (SEM) measurements (Hitachi S-4800 FE-SEM, 10 kV). Dried samples on silicon wafers were used for X-ray powder diffraction (XRD) analysis performed on a Rigaku D/ Max-2500 X-ray diffractometer with Cu Ka radiation (λ = 1.5406 Å), a voltage of 40 kV and a current of 200 mA. UV-Vis, CD and fluorescence spectra were obtained on Hitachi UV-3900, JASCO J-1500 spectrometers and a Hitachi F-4600 fluorescence spectrophotometer, respectively. Quartz cuvettes with light path of 0.1 mm were for organic gels, and 1 mm for dispersions. CPL measurements were performed a JASCO CPL-200 spectrometer. Absolute fluorescence quantum yield was obtained on an Edinburg FLS-980 fluorescence spectrometer


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equipped with calibrated integrating sphere. Fluorescence lifetime was measured on the same spectrometer using time-correlated single photon counting.

RESULTS AND DISCUSSION 1. Self-Assembly of the amphiphilic Schiff bases Gelation ability of the three amphiphilic Schiff bases was tested in some organic solvents such as acetonitrile, ethanol, acetone, and hexane. 1 and 2 were found to be able to form organogels in acetonitrile, but 3 cannot form stable gel in any solvents. Self-assembled structures of 1-3 in acetonitrile were characterized by SEM, as shown in Figure 1. Right-handed helical structures with pitch of about 900 nm, width of around 300 nm and length up to a few micrometres were formed by 1. Entangled fibrous structures were observed in the organogel of 2. In the case of compound 3, 2D flakes with width of 5 μm and length of 10 μm were found. The lack of three dimensional entanglements maybe the reason that a dispersion rather than a gel is formed by compound 3.

Figure 1. SEM images of the structures of the xerogels or precipitate from compound 1(A), 2(B) and 3(C) obtained in acetonitrile. In order to understand the supramolecular organization of the three amphiphilic Schiff bases, the packing modes of three nanostructures formed in acetonitrile were investigated by XRD measurements, as shown in Figure 2. All the three Schiff bases exhibit well-ordered lamellar


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structures. From the XRD pattern of 1, well defined diffractions corresponding to the d-spacing of 3.7, 1.8 and 1.2 nm can be identified. The ratio of the d-values follows the proportion about 1: 1/2: 1/3, indicating a lamellar arrangement of compound 1. While the molecular length of compound 1 amounts to 3.2nm, a d-spacing of 3.7 nm is larger than that the length of one molecule of compound 1, but smaller than the length of two molecules, indicating the formation of a bilayer structure via the interdigitation of alkyl chains.29 The d-spacing and molecular length of 2 amount to 4.0 nm and 3.2 nm, respectively, implying as well a bilayer stacking of 2. The dspacing of compound 3 is 2.5 nm, smaller than that of 1 and 2 and even the molecular length of compound 3 (2.9 nm). Given the similarity in molecular structure of the three compounds, possibly 3 also forms the bilayer stacking but with a large tilt.30 On the basis of XRD measurements, supramolecular arrangements of the three compounds are proposed and shown in Figure 2B. The linear shape of compound 1 and 2 is found, while the naphthalene ring is almost vertical to that of hydrophobic chains in compound 3. The linear shape of compound 1 and 2 may be favorable for the hydrogen bonding, resulting in the formation of one-dimensional structures, which is important to the formation of supramolecular gels.31 The steric hindrance between naphthalene ring in compound 3 may affect the formation of one-dimensional structures. Further, the strong  stacking between bilayers in compound 3 attributed to the precipitation in acetonitrile. And the  stacking also caused the fluorescence quenching of compound 3.


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Figure 2. (A) XRD patterns of 1 (black), 2 (red) and 3 (blue) in acetonitrile. (B) Proposed packing modes of the three molecules. Figure 3 depicts the UV-vis and fluorescence spectra of the three amphiphilic Schiff bases. From UV-Vis absorption spectra of compound 1, a band cantered at 345 nm and a broad band in the range of 415-435 nm can be observed, which we tentatively assigned to the adsorption of hydrogen bonded enol–imine form and keto-amine form, respectively. The band at 325 nm of 2 and the band at 317 nm of 3 can be assigned to the π–π* transitions of naphthalene ring and/or the imine chromophore. The bands appeared at 370 nm (2) and 365 nm (3) may be due to the hydrogen bonded enol–imine form. At visible region, the absorption bands in the range of 420460 nm of 2 and 415-435 nm of 3 indicate the existence of the keto-amine form.32 Relatively weak emissions at 480 nm and 510 nm were observed for 1 and 2 from their fluorescence spectra. However, there is almost no emission from 3 under the same condition.

Figure 3. (A) Absorption and (B) emission spectra of 1 (curve a), 2 (curve b) and 3 (curve c), (C) CD spectra of 1 (curve a) and 2 (curve b). (Conditions: gels formed in CH3CN with the


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concentration of 1×10-2 M for 1 and 2, but precipitate for 3, for FL spectrum the samples were excited at 365 nm). Since all the compounds are chiral, we measured their CD as well as CPL spectra, as shown in Figure 3C and Figure S5. The Cotton effects were observed at 420 nm for compound 1 and 450 nm for 2, indicating the chirality transfer from chiral carbon atom of glutamic acid to the Schiff base chromophore. But no apparent CD signal can be observed from compound 3, which may due to the strong scattering of the sample. We also investigated the CPL emissions of the three Schiff bases, but surprisingly all the three systems are CPL silent. A possible reason is that their fluorescent emission is too weak to be detected by CPL technique. Nevertheless, there are ways to enhance the fluorescence emission of Schiff bases. It has been reported that the fluorescence of Schiff base can be enhanced when it coordinates with some metal ions, due to inhibition of photo induced electron transfer (PET) and excited-state intramolecular proton transfer (ESIPT).33,34 Therefore we introduced metal ions in the system of amphiphilic Schiff bases in order to enhance their emission for the application as CPL materials. 2. Al3+ selectively turn on CPL of amphiphilic Schiff bases. In studying the metal ion-enhanced fluorescence of Schiff bases, we found that emission enhancement is most significant in ethanol. Then the following experiments were performed in ethanol. The electronic transition spectrum of compound 1 in ethanol displays (Figure 4A) characteristic absorption bands at 345 nm, 369 nm and 435 nm, which should be assigned to the π-π* transitions of imine chromophore, enol-imine configuration and keto-amine configuration of hydroxyl Schiff bases, respectively. In the presence of Al3+, only a single absorption band centered at 369 nm was observed, implying the complexation of Schiff base with aluminum. As


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for compound 2, absorption bands were observed at 327 nm, 420 nm and 445 nm. Upon the addition of equimolar Al3+, the absorption bands centered at 420 and 445 nm are blue shifted to 399 and 414 nm, respectively. As for compound 3, the absorption bands were observed at 336 nm, 404 nm and 422 nm, the latter two appear at lower wavelength than that of compound 2, suggesting that compound 2 has a larger conjugated system than compound 3. Similarly, the addition of Al3+ caused a blue shift of the absorption bands of 3, from to 385 and 400 nm, which is indicative of the coordination of Al3+ caused the existence of enol form of hydroxyl Schiff bases predominantly.

Figure 4. (A) Absorption and (B) emission spectra of compound 1 (curve a), 2 (curve b), 3(curve c), compound 1 with Al3+ (curve d) , compound 2 with Al3+ (curve e) and compound 3 with Al3+ (curve f) in ethanol; inset in B panel is a photograph of the complexes of compound 1-3 with Al3+ under 365 nm UV light irradiation. (C) The fluorescence emission spectra of compound 2 upon the addition of 0.18–2.2 equiv Al3+ in ethanol (ex = 365 nm). Inset: plot of the changes of fluorescence emission intensity at 465 nm. (D) Fluorescence decay of the 2-Al3+ complex (curve


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a, detected at 465 nm) and the 3-Al3+ complex (curve b, detected at 445 nm) in ethanol. ex = 365 nm. Figure 4B presents the emission spectra of 1-3 in the absence and presence of Al3+. Upon excitation at 365 nm, 1-3 display weak emission bands at 518 nm, 499 nm and 496 nm, respectively, due to the excited state intramolecular proton transfer (ESIPT) process.35 After interacting with Al3+ (1.0 equiv.), there is hardly any emission enhancement for Schiff base 1. Interestingly, the weak emission of 2 was almost 100 times enhanced upon the addition of Al3+, in line with a visible change of the fluorescence, from dark to light blue (Figure 4B, inset), under excitation. Similar emission enhancement was also observed for compound 3 when excited at 365 nm upon the addition of Al3+, but the enhancement is less pronounced as compared to that caused by complexion of 2 with Al3+. Together with absorption spectra, we suggested that the compound 2/Al3+ had larger conjugated system than that of compound 3/Al3+, which may cause difference in emission intensity. The fluorescence intensity of compound 2 increased almost linearly to the amount of Al3+ but remained steady when more than 1.0 equiv of Al3+ was applied (Figure 4C), suggesting a 1:1 binding mode between compound 2 and Al3+. To further investigate the binding stoichiometry of compound 2 and Al3+, Job’s plot analysis36,

37

(Figure S6) based on fluorescence spectra was

performed, in which the transition point for fluorescence intensity appeared at the molar fraction of 0.5, suggesting that compound 2 bound to Al3+ with a 1 : 1 molar ratio. Furthermore, the 1: 1 binding stoichiometry between compound 2 and Al3+ was also verified by ESI-MS spectrum of compound 2 and compound 2/Al3+. The ESI-MS spectrum of compound 2 exhibits a peak at m/z 804.7, which shifted to 866.6 upon the addition of Al3+, corresponding the mass of [compound 2 + Al3++ Cl-]+, confirming the 1 : 1 binding stoichiometry of the 2/Al3+ complex. (Figure S7)


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The fluorescence lifetime and quantum yield measurements confirm that the Al3+-induced emission enhanced is more efficient for compound 2. As shown in Figure 4D, the fluorescence lifetime is 10 ns for 2/Al3+ but 2 ns for compound 3/Al3+. In addition, a quantum yield of 72% was determined for compound 2/Al3+, but 16% for 3/Al3+. In a way, these results imply that compound 2 is a better sensor for Al3+ relative to the other two. Further, we tested the reaction of compound 2 and 3 to some other metal ions (Figure 5 A and 5B). The interaction of 2 with Zn2+ and Mg2+ results in emission at 457 nm and 453 nm, respectively, but no apparent fluorescence was observed when 2 was mixed with Co3+, Fe3+, Ag+ or Pb2+(Figure 5C, bar diagram). Similarly, emission was observed only when 3 was complexed with Al3+, Mg2+ or Zn2+. However, the intensities of 2/Zn2+ and 2/Mg2+ are much weaker than that of 2/Al3+, indicating the high sensitivity of Schiff base 2 for Al3+. The observed enhanced fluorescence is likely due to the metal ion-induced inhibition of the PET and ESIPT process via the complexation of Al3+ with imine (–HC=N) and hydroxyl groups, as shown in Figure 5D. In the absence of Al3+, the nitrogen atom of imine of compound 2 can partially transfer an electron to the naphthalene ring (PET ON) 38, 39 and a hydroxyl proton can be transferred to a neighboring imine nitrogen along with the formation of a intramolecular hydrogen bond (OH….N) (ESIPT), which leads to a relative weak fluorescent emission at 499 nm. Upon addition of Al3+ to the system of compound 2, the oxygen atoms of hydroxyl group and the nitrogen atom of the imine group participate in the coordination with Al3+, inhibiting the PET and ESIPT process, so that a remarkable enhancement of fluorescence happens at 465 nm.


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Figure 5. Color changes of (A) compound 2 in the presence of metal ions (top) under white light (bottom) under UV light at 365 nm. (B) Compound 3 in the presence of metal ions. (C) Bar diagram illustrates the emission intensity of compound 2 and its complexes with some metal ions in ethanol (at 465 nm), the concentration of compound 2 and metal ions is 50 M. (D) The proposed sensing mechanism of compound 2 with Al3+. Supramolecular chirality of the amphiphilic Schiff bases and the amphiphilic Schiff bases/Al3+ were studied with CD measurements, as shown in Figure 6A and Figure S8. We found that the CD spectra of ligands exhibited a negative Cotton effect, and a shift was observed after the addition of Al3+, which is consistent with the shifts of absorption bands, indicating that chirality of the glutamic acid is transferred to the Schiff bases/Al3+ complex. As for compound 2, we also investigated the supramolecular chirality of compound 2/Zn2+ and compound 2/Mg2+. In the presence of Zn2+ and Mg2+, negative Cotton effects were observed at 404 nm, as shown in Figure 6 A, indicated that chirality of the glutamic acid is effectively transferred to the Schiff


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base-metal ion complex. CPL emitting, a unique property of chiral systems, was further applied to investigate the excited-state supramolecular chirality. The luminescence dissymmetry factor (glum) was used to evaluate the magnitude of CPL, which is defined as glum = 2× (IL-IR)/(IL+IR), where IL and IR refer to the intensity of left and right-handed CPL, respectively.40 The CPL signal is silent for 1/Al3+, since the addition of Al3+ cannot enhance the emission of compound 1. The negative CPL signal appears at 465 nm and 445 nm for 2 and 3 in the presence of Al3+, respectively. The calculated value of the dissymmetry factor (|glum|) of the CPL signal is about 6.21×10-4 (2/Al3+) and 6.60×10-4 (3/Al3+), respectively. (Figure 6B). Although the fluorescence intensity and quantum yield of compound 2 and compound 3 with Al3+ are quite different, the glum of their CPL is similar. The dynamic light scattering (DLS) data of 2/Al3+ and 3/Al3+ complex indicated the assemblies with the size of 275 nm for 2/Al3+ and 244 nm for 3/Al3+ existed, respectively, as shown in Figure S9. We also found the positive CPL signal of the enantiomer of compound 2 with Al3+, as shown in Figure 6B. Meanwhile, its dissymmetry factor (|glum|) is close to compound 2. However, we could not observe CPL signal when aluminum chloride was replaced by aluminum nitrate or aluminum acetate, as shown in Figure S10. Therefore, this indicated that chloride ion also acted as the ligand, as shown in Figure 5D. It is worthy to note that although obviously Cotton effect and enhanced emission were observed for compound 2 in the presence of Zn2+ and Mg2+, no CPL signal was detected. And the silence of CPL signal for compound 2 in the presence of Zn2+ and Mg2+, probably could not simply ascribe to the low emission intensity of them. The reason for that need further explore.


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Figure 6. (A) CD spectra of (a)compound 2 and compound 2 in the presence of (b) Zn2+ (c) Mg2+ and (d) Al3+. (B) CPL spectra of compound 2/Al3+ (a) compound 3/Al3+ (b) and the enantiomer of compound 2/Al3+ (c) excited at 365 nm.

Figure 7. (up) Photo images of compound 2/Al3+ in the presence of other metal ions under UV light at 365 nm. (down) CPL spectra of compound 2/Al3+ complex in the presence of other competitive metal ions.


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To evaluate the selectivity of 2 to Al3+, we monitored the CPL spectra of compound 2 /Al3+ in the presence of other metal ions (Pb2+, Ag+, Fe3+, Co3+, Mg2+, Zn2+) (Figure 7). It was found that the coexistent metal ions did not affect the CPL profile of compound 2/Al3+ under the same conditions, which may due to the formation of a more stable complex of compound 2 with Al3+ as compared to other competitive metal ions. CONCLUSIONS In summary, three chiral Schiff bases have been designed and their supramolecular selfassemblies have been investigated. It was found that the amphiphilic Schiff bases synthesized from

4-(dimethylamino)-2-hydroxylbenzaldehyde

(compound

1),

and

1-hydroxy-2-

naphthaldehyde (compound 2) can form supramolecular gels with twist and fiber structures, while compound 3 synthesized from 2-hydroxy-1-naphthaldehyde cannot form organogels in any organic solvents we tested, suggesting that the subtle change in molecular structure can remarkably influence the self-assembly structures. Although compound 1 and 2 presented supramolecular chirality and emission, no CPL emission was observed. Upon addition of metal ions, particularly, the Al3+, the fluorescence will be significantly enhanced. The chelation of C=N and hydroxyl with Al3+ enhanced fluorescence of Schiff bases due to the prohibition of ESIPT process. Remarkably, the Al3+ coordinated with compound 2 and 3 exhibited CPL. Other metal ions like Zn2+ and Mg2+ can enhance the fluorescence and transfer the chirality but not CPL. Thus, we developed chiroptical materials based on Schiff bases and an Al3+ selective CPL sensor.

ASSOCIATED CONTENT Supporting Information include:


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NMR spectra, CD spectra, Job’s plot, DLS profile, and CPL spectra. AUTHOR INFORMATION Corresponding Authors E-mail: [email protected]，[email protected] ORCID iD Minghua Liu: 0000-0002-6603-1251 Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (21473219 and 21773260), Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12020200) and Key Research Program of Frontier Sciences, CAS, (QYZDJ-SSW-SLH044). REFERENCES 1. Kumar, J.; Nakashima, T.; Kawai, T. Circularly Polarized Luminescence in Chiral Molecules and Supramolecular Assemblies. J. Phys. Chem. Lett. 2015, 6, 3445-3452. 2. Zinna, F.; Pasini, M.; Galeotti, F.; Botta, C.; Di Bari, L.; Giovanella, U. Design of LanthanideBased OLEDs with Remarkable Circularly Polarized Electroluminescence. Adv. Funct. Mater. 2017, 27, 1603719. DOI: 10.1002/adfm.201603719. 3. Yang, Y.; da Costa, R. C.; Fuchter, M. J.; Campbell, A. J. Circularly polarized light detection by a chiral organic semiconductor transistor. Nat. Photonics 2013, 7, 634-638. 4. Li, M.; Li, S.H.; Zhang, D.; Cai, M.; Duan, L.; Fung, M.K.; Chen, C.F. Stable Enantiomers Displaying Thermally Activated Delayed Fluorescence: Efficient OLEDs with Circularly Polarized Electroluminescence. Angew. Chem. Int. Ed. 2018, 57, 2889-2893.


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Self-Assembly of Amphiphilic Schiff Base and Selectively

Turn

on

Circularly

Polarized

Luminescence by Al3+ Qingxian Jin,a Shuyu Chen,a,b Hejin Jiang,b Yuan Wang, b Li Zhang,*b Minghua Liu*b a

Henan Provincial Key Laboratory of Surface & Interface Science, Zhengzhou University of

Light Industry, Zhengzhou, Henan 450002,China. b

Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid Interface

and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190,China.

This work presents a simple way to fabricate CPL emitting materials based on the coordination between Schiff base and Al3+.


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Self-Assembly of Amphiphilic Schiff Base and Selectively Turn on

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