Chiral BINAPO-Controlled Diastereoselective Self-Assembly and

Jun 26, 2018 - Synopsis. Chiral R/S-BINAPO induce achiral tripodal ligand to assemble with Eu3+ forming a pair of enantiomeric podates with excellent ...
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Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

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Chiral BINAPO-Controlled Diastereoselective Self-Assembly and Circularly Polarized Luminescence in Triple-Stranded Europium(III) Podates Dan Liu, Yanyan Zhou, Yuan Zhang, Hongfeng Li,* Peng Chen, Wenbin Sun, Ting Gao, and Pengfei Yan*

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Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education; School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, P. R. China S Supporting Information *

ABSTRACT: Chiral lanthanide helical architectures have received intense attentions in recent years because of their potential applications as chiral probes and sensors and as circularly polarized luminescence (CPL) materials. However, stereoselectivity control in the self-assembly of lanthanide helicate is challenging due to the poor stereochemical preference and variable coordination numbers of Ln(III) ions. Herein, we reported the employing chiral ancillary ligand R/S-BINAPO to induce achiral tripodal ligand to form a pair of homochiral lanthanide triple-helical podates [Eu(TTEA)((R/S)-BINAPO); R/S-1] {(R/S)-BINAPO = (R/S)-2,2′-bis(diphenylphosphoryl)-1,1′-binaphthyl; TTEA = tris[(4-(4,4,4-trifluoro-1,3-dioxobutyl)-benzamido)ethyl]amine}. X-ray crystallographic analysis for rac-1 reveals that the chirality of BINAPO is transferred during the self-assembly process to give either P or M helical architectures in podates. The 1H and 31P NMR and circular dichroism measurements confirm the diastereopurity of the assemblies in solution. A detailed optical and chiroptical characterization reveals that the luminescent enantiopure podates not only exhibit intense CPL with |glum| values reaching 0.072 but also show high luminescence quantum yields of 32.8%. Our results provide a feasible strategy for designing homochiral helical lanthanide supramolecular architecture and synthesizing excellent CPL materials.

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INTRODUCTION

Currently, the use of transition-metal ions to achieve such structures is well-documented.7 In contrast, while lanthanide helical complexes have versatile spectroscopic properties,8 the poor stereochemical preference and variable coordination numbers (6−12) of Ln(III) ions make the precise prediction and control of helical twist direction during the self-assembly process remain a challenge. A recent example reported by Law and co-workers show that slight structural variations of chiral groups at the ligand termini lead to diastereoselective breaking to generate a mixture of P and M diastereomers of dinuclear Eu(III) triple-stranded helicates.9 In spite of these challenges, several enantiopure lanthanide helical architectures were successfully developed by Gunnlaugsson, Parker, and several others, where stereogenic centers attached to the termini or the linker units of the ligands determined the helical wrap fashion and chiral optical purity of the complexes.10 Because of the presence of chiral environments around metal centers of complexes, the luminescence from Ln(III) ions will exhibit light polarization, namely, CPL. As a special chiroptics phenomenon, CPL recently received large attention due to the potential applications in biological probes, three-dimensional (3D) displays, and optical storage.11 The intraconfigurational

The synthesis of chiral lanthanide supramolecular architectures is receiving intense attention because of their unique chiroptical properties and potential applications such as stereoselective guest recognition, chiral sensing, and as circularly polarized luminescence (CPL) materials.1−3 Helical structure is one of the most widely investigated architectures, which are intrinsically chiral, possessing either P or M helicity. A number of pioneering and fascinating lanthanide helical structures, including monometallic podates, bimetallic or multimetallic helicates, have been developed by Raymond, Piguet, Parker, and several other groups.4 Because of the absence of stereogenic center in ligands, these helical structures are usually formed in solution as racemic mixtures of P and M enantiomers. To explore these lanthanide assemblies for utilization in chiral applications, it is important to obtain a single enantiomer. However, the optically pure assembly is difficult to obtain by resolution of racemic enantiomers in solution, and only a few successful examples have been reported.5 Alternatively, control of stereoselectivity during selfassembly process is the most often used strategy. Generally, the introduction of point chiral or axial chiral moieties onto the ligands will transfer chiral information to an overall stereochemistry of self-assembled helical architectures.6 © XXXX American Chemical Society

Received: April 12, 2018

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DOI: 10.1021/acs.inorgchem.8b00986 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry Scheme 1. Synthesis of the Ligand TTEA and Corresponding Lanthanide Complexesa

a

Ln(TTEA)((R/S)-BINAPO), Ln = La, Eu, Gd. NMR confirmed the formation and purity of the intermediate and ligand (Figures S1−S4). The Ln(III) podates were obtained by stirring a 1:1:1 mixture of TTEA, (R/S)-BINAPO, and the corresponding Ln(III) salts in methanol at room temperature. Electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS) analyses confirmed the formation of the podates with a formula of Ln(TTEA)((R/S)-BINAPO). The molecular ion peaks assignments were also verified by carefully comparing the simulated isotopic patterns of the peaks with high-resolution experimental data (Figures S5−S10). To better understand how chiral (R/S)-BINAPO induces the helical twisting of the tripodal tris-β-diketone around the metal centers, we tried several methods to grow single crystals of the enantiomers. Unfortunately, all efforts were unsuccessful. However, interestingly, a single crystal of the racemic complex rac-Eu(TTEA)((R/S)-BINAPO) (rac-1) was obtained by slow evaporation of a solution of 1:1 mixture of R-1 and S-1 in chloroform/toluene/nhexane. X-ray crystallographic analysis reveals that rac-1 crystallizes in the monoclinic centrosymmetric space group P2/c with four individual podates in a unit cell, two of each of the R- and Senantiomers. As shown in Figure 1, the Eu(III) ion is eightcoordinated to six O atoms from three β-diketonate moieties and two O atoms from one R/S-BINAPO in a square antiprism configuration (Figure S11). The Eu−O distances are in the range of 2.354(8)− 2.431(6) Å, in which the distances to the coordinated R/S-BINAPO are on average ∼0.09 Å longer than that to β-diketonate units. Crystallographic parameters and selected bond lengths can be found in Tables S1. The structure shows that the introduction of (R)BINAPO induces three pendant β-diketonate moieties to helically wrap about a Eu(III) center in a Δ configuration and result in a P helical sense. In the case of (S)-BINAPO, the opposite M helical sense and a Λ configuration is observed. In this helical structure, the tripodal strands helically wrap the metal center with the average NCCN torsion angles being 50.25°. Moreover, a set of strong Hbonds (2.406 to 2.884 Å) between the H atoms of BINAPO and F, O atoms of TTEA can be observed in rac-1 (Figure S12). These H-bond interactions are proposed to contribute for inducing and stabilizing the homochiral helical structure, where rotation is precluded by conformational restriction brought on by steric constraints. Notably, the intramolecular H-bond interactions can only be found between BINAPO and two of the tripodal strands of TTEA, with the third one remaining free. Nevertheless, these interactions are still sufficient to stabilize the architecture and ensure achiral TTEA ligands wrapping

f−f transitions from Ln(III) ions, particularly those that obey magnetic dipole selection rules (ΔJ = 0 ± 1, except 0↔0), generally display a significantly higher luminescence dissymmetry factor glum, whose absolute values are 2−3 orders of magnitude higher than the ones obtained with purely organic molecules.12 Inspired by the fascinating chiroptical properties of helical lanthanide complexes, an achiral tripodal ligand (TTEA) is designed by grafting an amide linkage of the β-diketone binding units to [tris(2-aminoethyl)amine] (TREN) for constructing helical lanthanide podates. Lanthanide podates generally show large thermodynamic stability in solution.13 Moreover, the high kinetic inertness of the podates will reduce the numbers of conformational isomers, thus improving the diastereopurity of the assemblies. Because of the absence of stereogenic center, the self-assembly of ligand with Ln(III) ions will generally form racemic mixture of the homochiral helical architecture, which has been observed in several similar bis-β-diketone-based Ln(III) helicates reported by us.14 Herein, a “soft” approach that employs chiral ancillary ligand ((R/S)-2,2′-bis(diphenylphosphoryl)-1,1′-binaphthyl, (R/S)BINAPO) to induce the helical charity of the architecture is adopted. In comparison to a “hard” approach that employs optically pure chiral building blocks to produce chiral helicate, the inducing the achiral ligands to produce helical chirality (soft approach) will facilitate the construction of lanthanide chiral helical architecture. In addition, the developed βdiketone-based tripod will incorporate the powerful sensitization ability of β-diketones on Ln(III) ions luminescence and some advantages of the podates.

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EXPERIMENTAL SECTION

The synthesized procedures of the ligand TTEA and its corresponding complexes are outlined in Scheme 1 (for details, see the Supporting Information). First, 4-acetylbenzoic acid was reacted with tris(2-aminoethyl)amine (TREN) using standard peptidecoupling methodology15 to give the intermediate TAAB, which was then converted to the final ligand TTEA by a traditional Claisen condensation reaction with ethyl trifluoroacetate. 1H NMR and 13C B

DOI: 10.1021/acs.inorgchem.8b00986 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Figure 2. 31P NMR spectra of (a) (R)-BINAPO and La(TTEA)((R)BINAPO); (b) (S)-BINAPO and La(TTEA)((S)-BINAPO) in CD3Cl.

Figure 1. Representation of the crystallographic structure of Eu(TTEA)((R/S)-BINAPO) (R/S-1) in rac-1. (a) Side view of the complex R-1. (b) Side view of the complex S-1. (c) Top view of the complex R-1. (d) Top view of the complex S-1. around the metal ion with a right-handed or left-handed twist sense, forming a homochiral triple-helical podates. To assess the diastereopurity of the assemblies in solution, the 1H and 31P NMR spectroscopy was performed on the podates. Because of the poor resolution of the 1H NMR for Eu(III) complexes, the isostructural La(III) complexes, La(TTEA)((R/S)-BINAPO), were chosen as substitute for 1H NMR experiments (Figures S13 and S14). In 1H NMR spectra, three methine H protons of β-diketonate enol forms only show a broad singlet peak at 6.18 ppm, not the expected triplets due to the absence of C3 symmetry for the complexes. The singlet peak is presumably due to the signal overlaps of three methine H. Moreover, the signals at δ = 7.93−8.10 ppm assigned to amide protons show one set of triplet peaks, also not the expected three sets of triplet peaks, which still cannot confirm the diastereopurity of the complexes. However, when concerning the methylene protons, four broad singlets at δ = 2.50−4.10 are observed, which correspond to one set of 12 protons of a single diastereomer. Otherwise, two sets of data, eight peaks from two diastereomers, may be observed. Still, the broad and less-resolved signals could not conclusively confirm the presence of only one species in solution. Then an 800 MHz 1H NMR experiment is performed on La(TTEA)(R-BINAPO); however, the high-resolution spectrum does not show the clearer splits for the methylene protons and gives almost the same spectral pattern as that observed in 400 MHz NMR (Figure S15). Fortunately, in comparison to the room-temperature measurement, as the temperature decreases to 213 K, the four singlets split into nine peaks containing 12 protons, which should attribute to 12 different protons in one diastereomer, not the more complicated 24 protons for that in two diastereomers, although some overlaps can be observed (Figure S16). In addition, thanks to the presence of P atoms in podates, the corresponding 31P NMR spectra were then performed to further assess the diastereopurity of the podates. For La(TTEA)(R/S)-BINAPO, only one sharp singlet peak presents at 33.5 ppm (Figure 2). In summary, the above results could conclusively confirm the presence of a single diastereomer in solution. The UV−vis and CD spectra of R-1 and S-1 in CHCl3 are shown in Figure 3. The enantiomers show two major well-resolved π−π* transitions in the 230−280 and 300−400 nm ranges, which are attributed to the absorptions of (R/S)-BINAPO and TTEA in complexes. Compared with free ligands, the two bands both display ∼10 nm redshift (Figure S17). Notably, the free (R/S)-BINAPO also have weak absorbance at lower energy bands in the range of 270−325 nm. Thus, the absorbance of the complexes in 300−400 nm ranges should come from the combined contributions of two ligands. CD spectrum can reveal the chiroptical properties of the compounds in the ground state. As shown in Figure 3, the R-1 and S-1 exhibit mirror-image CD signals, which indicate that the enantiopure enantiomers were successfully isolated. On the one hand, according

Figure 3. UV−Visible absorption (lower curve, right axis) and CD spectra (upper curves, left axis) of R-1 (black lines) and S-1 (red lines) in CHCl3 (1.0 × 10−5 M). to comparison with the CD spectra of free (R/S)-BINAPO (Figure S18), strong Cotton effects at 255 nm (negative signal for S-1 and positive signal for R-1) and weak Cotton effects at 300 nm (negative signal for R-1 and positive signal for S-1) should be attributed to phosphine oxide ligands. On the other hand, moderately intense exciton couplets are visible for R/S-1 in the range of 310−400 nm, which are attributed to the exciton coupling between the π−π* transition of the achiral tripodal ligand (TTEA), centered at 340 nm. It indicates that the introduction of chiral phosphine oxide ancillary ligands succeeded in inducing chirality of achiral TTEA through intramolecular interactions. Furthermore, a negative exciton couplet is observed for R-1, corresponding to a Δ configuration for the local helicity environment around the Eu(III) ion; conversely, a positive exciton couplet associated with Λ configuration is observed for S-1. The CPL and PL spectra of R-1 and S-1 in CHCl3 are shown in Figure 4. The enantiomers exhibit almost identical emission spectra but show mirror-image CPL spectra. Upon excitation with the βdiketonate antennae moieties at 350 nm (Figure S19), four characteristic emission bands of Eu(III) ions are observed at 579, 593, 611, 650, and 700 nm, corresponding to 5D0 → 7FJ (J = 0−4) transitions, respectively. The relatively intense CPL signals are clearly observed in the spectral range of the 5D0 → 7F1, 7F2 transitions, which are magnetic and electronic-dipole transitions, respectively. In general, the magnetic dipole transition often shows particularly large circular polarization. The degree of the CPL is usually assessed in terms of the luminescent dissymmetry factor glum. Herein, glum = 2(IL − IR)/(IL + IR), where IL and IR represent the left and right polarized emission intensities, respectively (with −2 ≤ glum ≤ 2). The |glum| value for 5D0 → 7F1 transition of R/S-1 is found to be 0.072. On the one hand, the absolute glum value is comparable to the reported Eu-containing systems with chiral 2-hydroxyisophthalamide-, 1-hydroxy-2-pyridinone-, pyridyl diamide-, or DOTA-based ligand derivatives,16 and that containing BINAPO Eu(III) complex [Eu-(hfa)3(BINAPO)],17 while, on the other hand, the large CPL activities also indicate strong stereoselective control of chiral BINAPO on supramolecular selfC

DOI: 10.1021/acs.inorgchem.8b00986 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry

where kr is the radiative rate constant, knr is nonradiative rate constant, τobs is the observed lifetime, τrad is the radiative lifetime, AMD,0 = 14.65 s−1 is the spontaneous emission probability of the magnetic dipole 5D0 → 7F1 transition, and n is the refractive index of the medium. Itot is the total integrated emission of the 5D0 → 7FJ transitions, and IMD is the integrated emission of the 5D0 → 7F1 transition. These photophysical parameters in CHCl3 are summarized in Table 1. The high energy transfer efficiency (ηsens = 92.8%) benefits from the suitable energy gap (ΔE = 2263 cm−1) between triplet states of the β-diketonate moieties (T1 = 19 763 cm−1 estimated from their phosphorescent spectra (Figure S22) and the 5D0 energy level of Eu(III) ion (17 500 cm−1). Furthermore, the relatively small nonradiative rate constants (knr = 1.85 × 103 s−1) suggest the effective suppression of the nonradiative transition through the vibrational relaxation processes in the complexes. Similar observations have been made for several highly luminescent Eu(III) complexes with phosphine oxide as ancillary ligands.20

Figure 4. Total luminescence (lower curve, right axis) and CPL spectra (upper curves, left axis) of R-1 (black lines) and S-1 (red lines) in CHCl3 (λex = 350 nm, 1.0 × 10−5 M).

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CONCLUSIONS In summary, we have successfully synthesized a pair of enantiomeric podates with triple-stranded helical structure. The introduction of chiral BINAPO induces achiral tris-βdiketone (TTEA) to assemble with Ln(III) ion forming homochiral helical structure. From crystal structure analysis, it is found that hydrogen bonding is a guided dictator of these intramolecular interactions responsible in inducing achiral trisβ-diketone to form one-handed helical sense. Meanwhile, the introduction of BINAPO also induces chiroptical activities of TTEA in the excited state. It makes the Eu(III) complexes not only show strong circularly polarized luminescence but also significantly enhances the luminescence quantum yields of the complexes. Therefore, employing this soft approach provides a feasible strategy for designing homochiral lanthanide supramolecular architecture and synthesizing excellent CPL materials.21

assembly process. In other words, the absolute configuration of chiral phosphine oxide ancillary ligand controls the sign and magnitude of the CPL. It is noteworthy that R-1 with Δ configuration shows positive and negative CPL signals at 5D0 → 7F1 and 5D0 → 7F2 transition bands, respectively, while the S-1 with Λ configuration gives the mirror-image signals. Similar pattern can also be observed in the CPL and CD spectra for the Eu(III) complexes with the chiral 3heptafluorobutylryl-(+)-camphorato ligand.18 Therefore, the combination of these observations is very helpful for establishing empirical correlation between CPL spectral information and absolute configuration of lanthanide complexes. As excellent CPL materials, the luminescence quantum yield is another important parameter besides the glum for characterizing the performance of the materials. Absolute luminescence quantum yields of the Eu(III) complexes R/S-1 in CHCl3 are measured to be 32.8%, which is significantly higher than those reported chiral camphor- and pyridyl diamide-based lanthanide complexes with high glum (Φem < 2%).19 High emission quantum yields of the complexes mainly benefit from (1) effective sensitization ability of β-diketonate moieties on Eu(III) ions luminescence; (2) effective suppression of the nonradiative transition via vibrational relaxation in the complexes due to the introduction of BINAPO ancillary ligand, which exclude the coordinated solvent molecules from the primary coordination sphere of the metal ions and strength the rigidity of the podates. To clarify theses effects, we estimated sensitization efficiency and radiative (kr) and nonradiative (knr) rate constants of the complexes by using the emission lifetimes of the 5D0 → 7F2 transition of Eu(III) ion (τobs, Figures S20 and S21) and the following equations:20 Φoverall = ηsen ΦLn ΦLn =

kr =

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S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.8b00986. Details of the synthesis process, characterization, 1H NMR, 13C NMR spectra of TAEA, TTEA, 1H NMR spectra of complexes, ESI-TOF-MS of the complexes, UV−visible absorption spectra of Eu(TTEA)(R)BINAPO, (R)-BINAPO, and TTEA, TG patterns, crystal data, and structure refinement (PDF)

(1)

τ kr = obs k r + k nr τrad

Accession Codes

(2)

1 ji I zy = AMD,0n3jjj tot zzz j IMD z τrad k {

ASSOCIATED CONTENT

CCDC 1820167 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cam-

(3)

Table 1. Radiative (kr) and Nonradiative (knr) Decay Rates, Observed Luminescence Lifetime of Eu3+ (τEu obs), Intrinsic Quantum Yield (ΦLn), Sensitization Efficiency (ηsens), Quantum Yield of Eu3+ (ΦEu), Quantum Yield of Ligands (ΦL), and Overall Quantum Yield (Φoverall)a kr

knr

τobs

ΦLn

ηsens

Φoverall

glum 5D0 → 7FJ (J = 0, 1, 2, 3, 4)

complexes

(s−1)

(s−1)

(μs)

(%)

(%)

(%)

J=0

J=1

J=2

J=3

J=4

R-1 S-1

1016 1013

1854 1857

349 349

35.4 35.3

91.5 92.8

32.4 32.8

0.008 −0.008

0.072 −0.073

−0.005 0.005

0.017 −0.016

0.017 −0.017

5 7 3+ Error in τEu ion. obs: ±0.05 ms; 10% relative error in the other values; λex = 350 nm. glum values for D0 → FJ of Eu

a

D

DOI: 10.1021/acs.inorgchem.8b00986 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry

HOPO) Ligand. J. Am. Chem. Soc. 2015, 137, 2816−2819. (b) Shuvaev, S.; Starck, M.; Parker, D. Responsive, Water-Soluble Europium(III) Luminescent Probes. Chem. - Eur. J. 2017, 23, 9974− 9989. (c) Piguet, C.; Bünzli, J.-C. G. Self-Assembled Lanthanide Helicates: From Basic Thermodynamics to Applications. In Handbook on the Physics and Chemistry of Rare Earths; Elsevier: Amsterdam, Netherlands, 2010; Vol. 40, pp 301−533. (d) Dai, L.; Lo, W.-S.; Coates, I. D.; Pal, R.; Law, G.-L. New Class of Bright and Highly Stable Chiral Cyclen Europium Complexes for Circularly Polarized Luminescence Applications. Inorg. Chem. 2016, 55, 9065−9070. (e) Zare, D.; Suffren, Y.; Nozary, H.; Hauser, A.; Piguet, C. Controlling Lanthanide Exchange in Triple-Stranded Helicates: A Way to Optimize Molecular Light-Upconversion. Angew. Chem., Int. Ed. 2017, 56, 14612−14617. (5) (a) Cantuel, M.; Bernardinelli, G.; Muller, G.; Riehl, J. P.; Piguet, C. The First Enantiomerically Pure Helical Noncovalent Tripod for Assembling Nine-Coordinate Lanthanide(III) Podates. Inorg. Chem. 2004, 43, 1840−1849. (b) Walton, J. W.; Di Bari, L.; Parker, D.; Pescitelli, G.; Puschmann, H.; Yufit, D. S. Structure, Resolution and Chiroptical Analysis of Stable Lanthanide Complexes of a Pyridylphenylphosphinate Triazacyclononane Ligand. Chem. Commun. 2011, 47, 12289−12291. (c) Walton, J. W.; Carr, R.; Evans, N. H.; Funk, A. M.; Kenwright, A. M.; Parker, D.; Yufit, D. S.; Botta, M.; De Pinto, S.; Wong, K.-L. Isostructural Series of Nine-Coordinate Chiral Lanthanide Complexes Based on Triazacyclononane. Inorg. Chem. 2012, 51, 8042−8056. (6) Howson, S. E.; Scott, P. Approaches to the Synthesis of Optically Pure Helicates. Dalton Trans. 2011, 40, 10268−10277. (7) (a) Lehn, J.-M. Supramolecular Chemistry. Science 1993, 260, 1762−1763. (b) Lehn, J.-M. From Supramolecular Chemistry towards Constitutional Dynamic Chemistry and Adaptive Chemistry. Chem. Soc. Rev. 2007, 36, 151−160. (c) Howson, S. E.; Bolhuis, A.; Brabec, V.; Clarkson, G. J.; Malina, J.; Rodger, A.; Scott, P. Optically Pure, Water-Stable Metallo-Helical ‘Flexicate’ Assemblies with Antibiotic Activity. Nat. Chem. 2012, 4, 31−36. (d) Bunzen, J.; Bruhn, T.; Bringmann, G.; Lützen, A. Synthesis and Helicate Formation of a New Family of BINOL-Based Bis(bipyridine) Ligands. J. Am. Chem. Soc. 2009, 131, 3621−3630. (8) Eliseeva, S. V.; Bünzli, J.-C. G. Lanthanide Luminescence for Functional Materials and Bio-Sciences. Chem. Soc. Rev. 2010, 39, 189−227. (9) Yeung, C.-T.; Chan, W. T. K.; Yan, S.-C.; Yu, K.-L.; Yim, K.-H.; Wong, W.-T.; Law, G.-L. Lanthanide Supramolecular Helical Diastereoselective Breaking Induced by Point Chirality: Mixture or P-helix, M-helix. Chem. Commun. 2015, 51, 592−595. (10) (a) Lincheneau, C.; Peacock, R. D.; Gunnlaugsson, T. Europium Directed Synthesis of Enantiomerically Pure Dimetallic Luminescent “Squeezed” Triple-Stranded Helicates; Solution Studies. Chem. - Asian J. 2010, 5, 500−504. (b) Gregoliński, J.; Starynowicz, P.; Hua, K. T.; Lunkley, J. L.; Muller, G.; Lisowski, J. Helical Lanthanide(III) Complexes with Chiral Nonaaza Macrocycle. J. Am. Chem. Soc. 2008, 130, 17761−17773. (c) Lama, M.; Mamula, O.; Kottas, G. S.; De Cola, L.; Stoeckli-Evans, H.; Shova, S. Enantiopure, Supramolecular Helices Containing Three-Dimensional Tetranuclear Lanthanide(III) Arrays: Synthesis, Structure, Properties, and SolventDriven Trinuclear/Tetranuclear Interconversion. Inorg. Chem. 2008, 47, 8000−8015. (d) Frawley, A. T.; Pal, R.; Parker, D. Very Bright, Enantiopure Europium(III) Complexes Allow Time-Gated Chiral Contrast Imaging. Chem. Commun. 2016, 52, 13349−13352. (e) Zhang, T.; Zhang, G.-L.; Zhou, L.-P.; Guo, X.-Q.; Sun, Q.-F. Stereocontrolled Self-Assembly of Luminescent Lanthanide Helicates and Their Enantiodifferentiation using Δ-TRISPHAT as the NMR Resolving Agent. Tetrahedron: Asymmetry 2017, 28, 550−554. (f) Lama, M.; Mamula, O.; Kottas, G. S.; Rizzo, F.; De Cola, L.; Nakamura, A.; Kuroda, R.; Stoeckli-Evans, H. Lanthanide Class of a Trinuclear Enantiopure Helical Architecture Containing Chiral Ligands: Synthesis, Structure, and Properties. Chem. - Eur. J. 2007, 13, 7358−7373. (g) Stomeo, F.; Lincheneau, C.; Leonard, J. P.; O’Brien, J. E.; Peacock, R. D.; McCoy, C. P.; Gunnlaugsson, T. Metal-

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. (H.-F.L.) *E-mail: [email protected]. (P.-F.Y.) ORCID

Dan Liu: 0000-0002-2550-9669 Yanyan Zhou: 0000-0001-6504-4205 Yuan Zhang: 0000-0002-3689-8225 Hongfeng Li: 0000-0003-4646-0515 Peng Chen: 0000-0002-2689-0297 Wenbin Sun: 0000-0003-3358-050X Ting Gao: 0000-0002-6981-1886 Pengfei Yan: 0000-0002-5124-1707 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work is financially supported by the National Natural Science Foundation of China (Nos. 51773054, 51472076, & 21572048). We also thank the Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, P. R. China, for supporting this work.

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REFERENCES

(1) (a) Ito, H.; Shinoda, S. Chirality Sensing and Size Recognition of N-Boc-Amino Acids by Cage-type Dimeric Lanthanide Complexes: Chirality Detection of N-Boc-Aspartate Anions via Luminescence Colour Change. Chem. Commun. 2015, 51, 3808−3811. (b) Moussa, A.; Pham, C.; Bommireddy, S.; Muller, G. Importance of HydrogenBonding Sites in the Chiral Recognition Mechanism Between Racemic D3 Terbium(III) Complexes and Amino Acids. Chirality 2009, 21, 497−506. (2) (a) Zinna, F.; Di Bari, L. Lanthanide Circularly Polarized Luminescence: Bases and Applications. Chirality 2015, 27, 1−13. (b) Okutani, K.; Nozaki, K.; Iwamura, M. Specific Chiral Sensing of Amino Acids Using Induced Circularly Polarized Luminescence of Bis(diimine)dicarboxylic Acid Europium(III) Complexes. Inorg. Chem. 2014, 53, 5527−5537. (c) Pandya, S.; Yu, J.; Parker, D. Engineering Emissive Europium and Terbium Complexes for Molecular Imaging and Sensing. Dalton Trans. 2006, 23, 2757− 2766. (d) Butler, S. J.; Parker, D. Anion Binding in Water at Lanthanide Centres: From Structure and Selectivity to Signalling and Sensing. Chem. Soc. Rev. 2013, 42, 1652−1666. (3) (a) Zinna, F.; Giovanella, U.; Di Bari, L. Highly Circularly Polarized Electroluminescence From a Chiral Europium Complex. Adv. Mater. 2015, 27, 1791−1795. (b) Feuillastre, S.; Pauton, M.; Gao, L.; Desmarchelier, A.; Riives, A. J.; Prim, D.; Tondelier, D.; Geffroy, B.; Muller, G.; Clavier, G.; Pieters, G. Design and Synthesis of New Circularly Polarized Thermally Activated Delayed Fluorescence Emitters. J. Am. Chem. Soc. 2016, 138, 3990−3993. (c) Brandt, J. R.; Wang, X.; Yang, Y.; Campbell, A. J.; Fuchter, M. J. Circularly Polarized Phosphorescent Electroluminescence With a High Dissymmetry Factor From PHOLEDs Based on a Platinahelicene. J. Am. Chem. Soc. 2016, 138, 9743−9746. (d) Yeung, C.-T.; Yim, K.-H.; Wong, H.-Y.; Pal, R.; Lo, W.-S.; Yan, S.-C.; Wong, M. Y.M.; Yufit, D.; Smiles, D. E.; McCormick, L. J.; Teat, S. J.; Shuh, D. K.; Wong, W.-T.; Law, G.-L. Chiral Transcription in Self-Assembled Tetrahedral Eu4L6 Chiral Cages Displaying Sizable Circularly Polarized Luminescence. Nat. Commun. 2017, 8, 1128. (4) (a) Daumann, L. J.; Tatum, D. S.; Snyder, B. E. R.; Ni, C.; Law, G.-L.; Solomon, E. I.; Raymond, K. N. New Insights into Structure and Luminescence of EuIII and SmIII Complexes of the 3,4,3-LI(1,2E

DOI: 10.1021/acs.inorgchem.8b00986 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry Directed Synthesis of Enantiomerially Pure Dimetallic Lanthanide Luminescent Triple-Stranded Helicates. J. Am. Chem. Soc. 2009, 131, 9636−9637. (11) (a) Muller, G. Luminescent Chiral Lanthanide(III) Complexes as Potential Molecular Probes. Dalton Trans. 2009, 44, 9692−9707. (b) Carr, R.; Evans, N. H.; Parker, D. Lanthanide Complexes as Chiral Probes Exploiting Circularly Polarized Luminescence. Chem. Soc. Rev. 2012, 41, 7673−7686. (c) Carr, R.; Di Bari, L.; Lo Piano, S.; Parker, D.; Peacock, R. D.; Sanderson, J. M. A Chiral Probe for the Acute Phase Proteins Alpha-1-Acid Glycoprotein and Alpha-1Antitrypsin Based on Europium Luminescence. Dalton Trans. 2012, 41, 13154−13158. (d) Nishimura, H.; Tanaka, K.; Morisaki, Y.; Chujo, Y.; Wakamiya, A.; Murata, Y. Oxygen-Bridged Diphenylnaphthylamine as a Scaffold for Full-Color Circularly Polarized Luminescent Materials. J. Org. Chem. 2017, 82, 5242−5249. (e) Kumar, J.; Nakashima, T.; Kawai, T. Circularly Polarized Luminescence in Chiral Molecules and Supramolecular Assemblies. J. Phys. Chem. Lett. 2015, 6, 3445−3452. (12) (a) Field, J. E.; Muller, G.; Riehl, J. P.; Venkataraman, D. Circularly Polarized Luminescence from Bridged Triarylamine Telicenes. J. Am. Chem. Soc. 2003, 125, 11808−11809. (b) Zinna, F.; Di Bari, L. Lanthanide Circularly Polarized Luminescence: Bases and Applications. Chirality 2015, 27, 1−13. (13) (a) Comby, S.; Imbert, D.; Chauvin, A.-S.; Bünzli, J.-C. G. Stable 8-Hydroxyquinolinate-Based Podates as Efficient Sensitizers of Lanthanide Near-Infrared Luminescence. Inorg. Chem. 2006, 45, 732−743. (b) Ryan, P. E.; Canard, G.; Koeller, S.; Bocquet, B.; Piguet, C. Allosteric Effects in Binuclear Homo- and Heterometallic Triple-Stranded Lanthanide Podates. Inorg. Chem. 2012, 51, 10012− 10024. (14) (a) Li, B.; Li, H.; Chen, P.; Sun, W.; Wang, C.; Gao, T.; Yan, P. Enhancement of Near-Infrared Luminescence of Ytterbium in TripleStranded Binuclear Helicates. Phys. Chem. Chem. Phys. 2015, 17, 30510−30517. (b) Li, B.; Li, H.; Chen, P.; Sun, W.; Wang, C.; Gao, T.; Yan, P. Insight into the Roles of Structures and Energy Levels of Mono- and Bis-β-Diketones on Sensitizing Nd(III) NIR-Luminescence. Dalton Trans. 2016, 45, 11459−11470. (15) Kotova, O.; Blasco, S.; Twamley, B.; O’Brien, J.; Peacock, R. D.; Kitchen, J. A.; Martínez-Calvo, M.; Gunnlaugsson, T. The Application of Chiroptical Spectroscopy (Circular Dichroism) in Quantifying Binding Events in Lanthanide Directed Synthesis of Chiral Luminescent Self-Assembly Structures. Chem. Sci. 2015, 6, 457−471. (16) (a) Bonsall, S. D.; Houcheime, M.; Straus, D. A.; Muller, G. Optical Isomers of N,N′-Bis(1-phenylethyl)-2,6-pyridinedicarboxamide Coordinated to Europium(III) Ions as Reliable Circularly Polarized Luminescence Calibration Standards. Chem. Commun. 2007, 35, 3676−3678. (b) Petoud, S.; Muller, G.; Moore, E. G.; Xu, J.; Sokolnicki, J.; Riehl, J. P.; Le, U. N.; Cohen, S. M.; Raymond, K. N. Brilliant Sm, Eu, Tb, and Dy Chiral Lanthanide Complexes with Strong Circularly Polarized Luminescence. J. Am. Chem. Soc. 2007, 129, 77−83. (c) Leonard, J. P.; Jensen, P.; McCabe, T.; O’Brien, J. E.; Peacock, R. D.; Kruger, P. E.; Gunnlaugsson, T. Self-Assembly of Chiral Luminescent Lanthanide Coordination Bundles. J. Am. Chem. Soc. 2007, 129, 10986−10987. (d) Seitz, M.; Do, K.; Ingram, A. J.; Moore, E. G.; Muller, G.; Raymond, K. N. Circularly Polarized Luminescence in Enantiopure Europium and Terbium Complexes with Modular, All-Oxygen Donor Ligands. Inorg. Chem. 2009, 48, 8469−8479. (17) Harada, T.; Nakano, Y.; Fujiki, M.; Naito, M.; Kawai, T.; Hasegawa, Y. Circularly Polarized Luminescence of Eu(III) Complexes with Point- and Axis-Chiral Ligands Dependent on Coordination Structures. Inorg. Chem. 2009, 48, 11242−11250. (18) (a) Lunkley, J. L.; Shirotani, D.; Yamanari, K.; Kaizaki, S.; Muller, G. Chiroptical Spectra of a Series of Tetrakis((+)-3heptafluorobutylyrylcamphorato)lanthanide(III) with an Encapsulated Alkali Metal Ion: Circularly Polarized Luminescence and Absolute Chiral Structures for the Eu(III) and Sm(III) Complexes. Inorg. Chem. 2011, 50, 12724−12732. (b) Lunkley, J. L.; Shirotani, D.; Yamanari, K.; Kaizaki, S.; Muller, G. Extraordinary Circularly

Polarized Luminescence Activity Exhibited by Cesium Tetrakis(3heptafluoro-butylryl-(+)-camphorato) Eu(III) Complexes in EtOH and CHCl3 Solutions. J. Am. Chem. Soc. 2008, 130, 13814−13815. (19) (a) Kumar, J.; Marydasan, B.; Nakashima, T.; Kawai, T.; Yuasa, J. Chiral Supramolecular Polymerization Leading to Eye Differentiable Circular Polarization in Luminescence. Chem. Commun. 2016, 52, 9885−9888. (b) Kotova, O.; Kitchen, J. A.; Lincheneau, C.; Peacock, R. D.; Gunnlaugsson, T. Probing the Effects of Ligand Isomerism in Chiral Luminescent Lanthanide Supramolecular SelfAssemblies: A Europium “Trinity Sliotar” Study. Chem. - Eur. J. 2013, 19, 16181−16186. (c) Hua, K. T.; Xu, J.; Quiroz, E. E.; Lopez, S.; Ingram, A. J.; Johnson, V. A.; Tisch, A. R.; de Bettencourt-Dias, A.; Straus, D. A.; Muller, G. Structural and Photophysical Properties of Visible- and Near-IR-Emitting Tris Lanthanide(III) Complexes Formed with the Enantiomers of N,N′-Bis(1-phenylethyl)-2,6pyridinedicarboxamide. Inorg. Chem. 2012, 51, 647−660. (20) Werts, M. H. V.; Jukes, R. T. F.; Verhoeven, J. W. The emission spectrum and the radiative lifetime of Eu3+ in luminescent lanthanide complexes. Phys. Chem. Chem. Phys. 2002, 4, 1542−1548. (21) (a) Raj, D. B. A.; Francis, B.; Reddy, M. L. P.; Butorac, R. R.; Lynch, V. M.; Cowley, A. H. Highly Luminescent Poly(Methyl Methacrylate)-Incorporated Europium Complex Supported by a Carbazole-Based Fluorinated β-Diketonate Ligand and a 4,5-Bis(diphenylphosphino)-9,9-dimethylxanthene Oxide Co-Ligand. Inorg. Chem. 2010, 49, 9055−9063. (b) Vicente, J. A.; Mlonka, A.; Gunaratne, H. Q. N.; Swadźba-Kwaśny, M.; Nockemann, P. Phosphine Oxide Functionalised Imidazolium Ionic Liquids as Tuneable Ligands for Lanthanide Complexation. Chem. Commun. 2012, 48, 6115−6117. (c) Wang, J.; Han, C.; Xie, G.; Wei, Y.; Xue, Q.; Yan, P.; Xu, H. Solution-Processible Brilliantly Luminescent EuIII Complexes with Host-Featured Phosphine Oxide Ligands for Monochromic Red-Light-Emitting Diodes. Chem. - Eur. J. 2014, 20, 11137−11148.

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DOI: 10.1021/acs.inorgchem.8b00986 Inorg. Chem. XXXX, XXX, XXX−XXX