Synthesis, Structure, and Properties of a Series of Chiral Coordination

Article pubs.acs.org/crystal

Synthesis, Structure, and Properties of a Series of Chiral Coordination Polymers Based on (R)‑4-(4-(1Carboxyethoxy)phenoxy)-3-chlorobenzoic Acid Ying-Hui Yu,†,‡ Han-Tao Ye,†,‡ Guang-Feng Hou,*,†,‡ Chang-Yue Ren,†,‡ Jin-Sheng Gao,*,†,‡ and Peng-Fei Yan‡ †

Engineering Research Center of Pesticide and ‡School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China S Supporting Information *

ABSTRACT: Three isomorphic chiral coordination polymers, namely, [M(cpca)·(H2O)]2·H2O (M = Zn (1), Cd (2), and Co (3)), based on a new homochiral dicarboxylic acid ligand, have been synthesized under hydro(solvo)thermal conditions and characterized by single X-ray diffractions, elemental analyses, infrared spectra, thermogravimetric analysis, powder X-ray diffractions, and circular dichroism spectroscopy. The three compounds featured twodimensional layer structures with one-dimensional pseudo-nanotubes connected together by weak intermolecular interactions, exhibiting a new topological structure with a point symbol of (43·62·8). The influence of ionic radii in tuning the pore size of the coordination polymers is discussed. Furthermore, second harmonic generation (SHG) activity, luminescence and sensing, and asymmetric catalytic properties of all these three chiral coordination polymers have also been studied. All the three complexes show different SHG activities. The luminescence of the complexes could be quenched by nitrobenzaldehyde, which may be used for molecular sensing and recognizing. The three complexes also demonstrate asymmetric catalysis activities toward Henry reactions of nitroaldehyde.

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INTRODUCTION Coordination polymers (CPs) are versatile scaffolding materials with highly ordered structures and a modular nature which could be constructed from designer building blocks to impart different properties for potential applications in several fields.1−17 In particular, designed and directed synthesis of chiral coordination polymers (CCPs) has aroused the remarkable attention of most chemists not only owing to their fascinating topological structures,18−21 but also for their unique aspects in nonlinear optics (NLO),22−25 chiral recognition and separation,26−29 especially in asymmetric catalysis.30−32 Since Kim et al. reported the first example of CCPs’ asymmetric catalytic property in 2000,33 CCPs appear to be excellent candidates in the field of catalysis for their tunable and high dimensional structures, active sites with different strengths generated in the frameworks, and uniform size of their channels and cavities.34−40 Up to now, two schemes are widely used to build CCPs. Post modification is one efficient way to get CCPs from a robust CPs.41−44 Many examples have shown that CCPs could be successfully obtained by post modification; however, how to keep the pore size in the framework and achieve asymmetric catalytic properties are still big challenges.45 Molecular selfassembly of homochiral ligand and metal ions seems to be an easier and more promising way to get expected CCPs with © XXXX American Chemical Society

pores large enough for catalysis compared with post modification.46−51 Yet, up to now, most of the reported CCPs with asymmetric catalytic activities are built by rigid ligands, the structures of which featuring wide-open pores as the active center of catalysis.52−54 Whether the CCPs with small channels constructed from semirigid or flexible ligands have asymmetric catalytic activities or not, so far, as we known, few reports can answer this question.55−57 As one of our ongoing efforts in the synthesis of asymmetric catalytic crystalline materials, we were prompted to design and synthesize a chiral semirigid ligand dicarboxylic acid (R)-4-(4(1-carboxyethoxy)phenoxy)-3-chlorine acid (H2cpca) (Scheme 1). Considering that different metal ions could exhibit different catalytic abilities and might influence the pore size and structures of CCPs,58 we choose three transition metals M(II) as center metals reacting with H2cpca to obtain three isomorphic chiral coordination polymers, namely, [M(cpca)· (H2O)]2·H2O (M = Zn (1), Cd (2), and Co (3)). These CCPs were characterized by X-ray crystallography, elemental analyses, infrared (IR) spectra, powder X-ray diffraction (PXRD), thermogravimetric analyses (TGA), circular dichroism specReceived: April 18, 2016 Revised: August 26, 2016

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DOI: 10.1021/acs.cgd.6b00593 Cryst. Growth Des. XXXX, XXX, XXX−XXX

Crystal Growth & Design

Article

(1.0 mol/L) to obtain a white solid of H2cpfa after being dried in air. The solid was filtered off, washed with water, dried, and recrystallized with acetonitrile (yield 80%) to get crystals suitable for testing. Anal. Calcd for C16H13ClO6 (336.72): C, 57.07; H, 3.89%. Found: C, 56.98; H, 3.77%. 1H NMR (DMSO-d6):δ 13.01 (2H, s), 8.02 (1H, d), 7.85 (1H, dd), 7.09 (2H, d), 6.96 (2H, d), 6.88 (1H, d), 4.83 (1H, q), 1.52 (3H, d). IR (KBr, cm−1) 3445 (m), 2994 (m), 1709 (s), 1598 (m), 1495 (vs), 1421 (m), 1264 (s), 1230 (vs), 836 (m). UV−vis (MeOH, λmax): 252 nm. Synthesis of {[M(cpca)·(H2O)]2·H2O}n (M = Zn (1), Cd (2), and Co (3)). A mixture of 0.2 mmol M(OAc)2·xH2O (M = Zn and Cd, x = 2; M = Co, x = 4) and 0.2 mmol of H2cpca, 0.4 mmol of NaOH, 4 mL of ethanol, and 4 mL of H2O was stirred for 2 h in air and then transferred and sealed in a Teflon reactor (15 mL), which was heated at 120 °C for 72 h, and then cooled to room temperature at a rate of 10 °C/h. {[Zn(cpca)·(H2O)]2·H2O}n (1). Colorless crystals of 1 were obtained in 50% yield (based on Zn(OAc) 2 ·2H2 O). Anal. calcd for C32H28Zn2O15Cl2 (854.18): C, 44.96; H, 3.28%. Found: C, 45.06; H, 3.31%. IR (KBr, cm−1): 3374 (s), 3078 (m), 2996 (m), 2921 (m), 1602 (vs), 1503 (vs), 1410 (vs), 1268 (s), 1236 (s), 1133 (m), 1098 (m), 1060 (m), 915 (m), 846 (m), 781 (m), 519 (m). {[Cd(cpca)·(H2O)]2·H2O}n (2). Colorless crystals of 2 were obtained in 41% yield (based on Cd(OAc)2·2H2O). Anal. Calcd for C32H28Cd2O15Cl2 (944.21): C, 40.67; H, 2.97%. Found: C, 40.55; H, 3.11%. IR (KBr, cm−1): 3412 (s), 3047 (m), 2918 (m), 1690 (s), 1587 (s), 1502 (s), 1426 (s), 1273 (s), 1235 (s), 1196 (s), 1124 (s), 845 (s), 725 (s), 612 (s). {Co(cpca)·(H2O)]2·H2O}n (3). Pink crystals of 3 were obtained in 35% yield (based on Co(OAc) 2 ·4H 2 O). Anal. Calcd for C32H28Cl2Co2O15 (841.30): C, 45.64; H, 3.33%. Found: C, 45.53; H, 3.19%. IR (KBr, cm−1): 3375 (s), 3078 (m), 2993 (m), 2930 (m), 1593 (vs), 1507 (vs), 1414 (vs), 1267 (s), 1233 (s), 1196 (s), 1055 (m), 915 (m), 850 (m), 777 (m). Catalytic Studies. Aromatic nitroaldehyde (1 mmol) and nitromethane (10 mmol) were added to a methanol (10 mL) solution of catalyst (10 mol %), and the mixture was stirred for 24 h at 25 °C. Then the mixture was evaporated in vacuo. The products were separated by preparative thin layer chromatography (TLC) performed on dry silica gel plates with ethyl acetate/petroleum ether (1:5 v/v) as the developing solvent. The main products were collected and dried in vacuo. X-ray Crystallography. Single-crystal X-ray diffraction data for H2cpca and complexes 1−3 were collected on a Rigaku R-AXIS RAPID imaging plate diffractometer with graphite-monochromated Mo Kα (λ = 0.71073 Å) at 291 K. Empirical absorption corrections based on equivalent reflections were applied. The structures of them were solved by direct methods and refined by full-matrix least-squares methods on F2 using the SHELXS-97 crystallographic software package.59 The crystal parameters, data collection, and refinement results for H2cpca and complexes 1−3 are summarized in Table 1. Selected bond lengths and angles of complexes 1−3 are listed in Table S1, and the H-bond lengths and angles are shown in Table S2 (see the Supporting Information). Crystallography data have been deposited to the Cambridge Crystallography Data Centre with deposition numbers CCDC nos. 1426284−1426287 for H2cpca and CCPs 1−3.

Scheme 1. Synthesis of CCPs 1−3 by Ligand H2cpca and Different Transition Metals

troscopy (CD), and second harmonic generation (SHG). Their structures and the supramolecular assembly by H-bonds have been discussed in detail. Furthermore, the luminescent, chemical sensing, and asymmetric catalytic properties were also investigated.

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EXPERIMENTAL SECTION

Materials and Measurements. All the solvents and reagents for synthesis were commercially available and used as received. C, H, and N analyses were performed on a PerkinElmer 2400 elemental analyzer. IR spectra were recorded with a Spectrum one Fourier transform infrared (FT-IR) spectrometer using KBr pellets in the range of 400− 4000 cm−1. The PXRD data of the samples were collected on a Rigaku D/MAX-3B diffractometer using Cu−Kα radiation (λ = 1.5418 Å) and 2θ ranging from 5 to 50°. TGA were completed on a PerkinElmer STA 6000 thermal analyzer at a heating rate of 10 °C·min−1. The luminescent spectrum was taken on a Perkin Elemer Corporation model fluorescence spectrometer LS 55 PL. PL spectroscopy was performed in solid samples after the crystals were dissolved in methanol. The second-order nonlinear optical intensities were estimated by measuring microcrystalline samples relative to urea by a Spectra Physics Quanta Ray Prolab 170 Nd:YAG laser using the firstharmonics output of 1064 nm with a pulse width of 10 ns and a repetition rate of 10 Hz. Enantiomeric excess of products was tested by HPLC analysis using a chiral column Ultimate Cellud-Y. The CD spectra of the compounds were recorded at room temperature with a Jasco J-810(S) spectropolarimeter (KCl pellets).

Scheme 2. Schematic Synthesis Route of H2cpca

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Synthesis of (R)-4-(4-(1-Carboxyethoxy)phenoxy)-3-chlorobenzoic Acid (H2cpca). Anhydrous potassium carbonate (6.9 g, 50 mmol) was added to a DMF solution (100 mL) of (R)-(+)-2-(4hydroxyphenoxy)propionic acid (3.9 g, 20 mmol), and the mixture was stirred for 3 h at 80 °C, to which 3,4-dichlorobenzonitrile (3.4 g, 20 mmol) was then added and stirred at 100 °C for 10 h. The solvent was then removed from the mixture by evaporation, and 100 mL of water was added. The pH value was adjusted to 1−2 by cooled hydrochloric acid (1.0 mol/L) to get (R)-2-(4-(2-chloro-4-cyanophenoxy)phenoxy)propanoic acid (I). Step 2: A mixture of I (15.0 g, 50 mmol) and NaOH (10.0 g, 25 mmol) in water (100 mL) was stirred at 100 °C for 10 h. After the mixture was cooled to room temperature, the pH of the mixture was adjusted to 4−5 by cooled hydrochloric acid

RESULTS AND DISCUSSION Crystal Structure of H2cpca. The single-crystal X-ray diffraction study shows that two H2cpca and one acetonitrile molecules cocrystallize in a chiral space group C2221. As shown in Figure 1a, the two craboxylic groups in H2cpca exhibit cis configuration. The chiral carbon shows the same R configuration as that in the starting material of (R)-(+)-2-(4hydroxyphenoxy)propionic acid (Figure 1b). Moreover, two H2cpca molecules are connected by hydrogen bonds to form an M chiral chain. B



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Table 1. Crystal Data and Structure Refinement for H2cpca and Complexes 1−3

a

crystal parameters

H2cpca

CCP-1

CCP-2

CCP-3

empirical formula formula weight crystal system space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z Dcaled (Mg cm−3) μ (mm−1) collected/unique Flack value Rint GOF on F2 R1,a wR2b (I > 2σ(I)) R1,a wR2b (all data)

C34H29Cl2NO12 714.48 orthorhombic C2221 6.8630(14) 23.174(5) 22.172(4) 90 90 90 3526.4(12) 4 1.346 0.247 16566/4005 0.05(9) 0.0496 1.037 0.0459, 0.1184 0.0779, 0.1360

C32H28Zn2Cl2O15 854.18 monoclinic C2 17.352(4) 7.2308(14) 15.734(3) 90 118.74(3) 90 1730.9(6) 2 1. 639 1.612 8540/3817 0.021(16) 0.0521 1.060 0.0427, 0.0922 0.0555, 0.0973

C32H24Cd2Cl2O15 944.21 monoclinic C2 17.5900(8) 7.3305(2) 15.9628(7) 90 119.024(6) 90 1799.81(12) 2 1.742 1.399 8110/3373 0.02(3) 0.0309 1.051 0.0301, 0.0669 0.0345, 0.0696

C32H28Cl2Co2O15 841.30 monoclinic C2 17.368(4) 7.1859(14) 15.735(3) 90 118.47(3) 90 1726.4(6) 2 1.618 1.187 8496/3593 −0.003(17) 0.0459 1.092 0.0401, 0.0859 0.0470, 0.899

R1 = (Σ∥Fo| − |Fc|)/Σ|Fo|. bwR2 = [Σw(Fo2 − Fc2)2/Σw(Fo2)2]1/2.

Figure 1. (a) Stick-ellipsoid representation of the molecule of H2cpca with thermal ellipsoids at 50% probability; the H atoms were omitted for clarity. (b) The R configuration of chiral carbon. (c) 1D chain with M chirality was built by intermolecular H-bonds.

Figure 2. (a) Stick-ellipsoid representation of the asymmetric unit of complex 1 with thermal ellipsoids at 50% probability; the H atoms were omitted for clarity. (b) Zn(II) coordination environment. (c) Polyhedral representation of the infinite 1D rod SBUs. Symmetric codes: I: −x + 1, y − 1, −z; II: −x + 3/2, y − 1/2, −z + 1; III: x + 1/2, y − 1/2, z + 1.

Crystal Structure of Complexes 1−3. Single-crystal X-ray diffraction analyses show that complexes 1−3 are isomorphic, and therefore only complex 1 is described here in detail. The asymmetric units of complexes 2 and 3 are shown in Figures S1 and S2. Complex 1 crystallizes in a monoclinic system with C2 space group. As shown in Figure 2a, the asymmetric unit of 1 contains one crystallographically independent Zn(II) ion, one cpca2− anion, one coordinated water molecule, and half lattice water molecule. The Zn(II) ion is six-coordinated by five carboxylic oxygen atoms from four different cpca2− anions and one coordination water molecule, furnishing a distorted {ZnO6} octahedral geometry. The Zn−O distances are in the range of 2.038(3)−2.333(3) Å. It is noted that each {ZnO6} polyhedron shares corner with two neighboring ones and extends into a one-dimensional (1D) inorganic Zn−O−Zn chain along the b axis (Figure 2b). In 1, the cpca2− anions of two carboxylic groups take a trans configuration and exhibit μ2-η1:η1 and μ2-η1:η2 coordination fashions. The inorganic Zn−O chains are connected by cpca2− anions, forming a 1D square-shaped tube (Figure 3a). Meanwhile, induced by the chiral ligand, the Zn-cpca chain exhibits M chirality along [010]. Furthermore, the tubes are

Figure 3. (a) A 1D square-shaped tube was formed by cpca2− anions connecting with SBUs. (b) An M chirality chain made by Zn-cpca. (c) View of the 2D layers piled with 1D pseudo-nanotubes. (d) H2cpca simplified as a four-connect node. (e) New topological structure of complex 1 with a point symbol of (43·62·8).

connected together by weak intermolecular interactions to form a two-dimensional (2D) layer with 1D pseudo-nanotubes. As reported before, this 2D layer can be classified as I1O1 type in inorganic−organic hybrid complexes, which is relatively rare.60−62 If we consider the cpca2− anions and Zn(II) ions C



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as four connected nodes, complex 1 can be simplified as a (4,4)-connected topological structure with a point symbol of (43.62.8) calculated by the TOPOS 4, which has not been reported before (Figure 3d,e).63 As shown in Figure 4, in complex 1, (H2O)3 clusters formed by O−H···O bonds connect the 2D layers into a three-

The first weight loss of complex 3 in the range of 110−170 °C is consistent with the removal of two coordination water molecules and one lattice water (found, 6.33%; calcd. 6.42%). The second step occurs from 320 to 530 °C owing to the release of cpca2− anions (found, 77.17%; calcd, 79.57%). Single-crystal X-ray structure determinations are often combined with CD spectroscopy to confirm the homochirality or enantio enrichment of the bulk materials. The solid-state CD spectra were recorded in a KCl matrix with the chosen bulk crystals. The positive signals and strong Cotton effect shown in Figure 5 indicate the homochirality of complexes 1−3 and H2cpca.

Figure 4. (a) Trimer water molecules built by H-bonds in complex 1. (b) 3D supramolecule made by 2D layers connected by H-bonds. (c) Supramolecular structure with (4,8)-connected sq22 topology (the blue color represents coordination bonds and the green one represents H-bonds).

Figure 5. Solid-state CD spectra of bulk samples of complexes 1−3 and H2cpca.

Second-Harmonic Generation Efficiency. Considering that chiral ligand and complexes 1−3 all crystallized in chiral space group C2221 and C2, their nonlinear optical properties were investigated. According to the method proposed by Kurtz and Perry, the SHG efficiency can be measured by using a powder technique.64 The SHG efficiency is compared with a standard material, such as α-quartz, KH2PO4 (KDP), or urea. KDP has an efficiency of 16 × α-quartz, whereas urea has an efficiency of 400 × α-quartz. The technologically important LiNbO3 is 600 × α-quartz. In this work, the SHG efficiencies of 1−3 are measured by using pure microcrystalline samples, and the results are in contrast with urea. Crystallized in chiral space group C2, complexes 1−3 show a homochiral 2D layer structure constructed by 1D pseudonanotubes. The SHG activities of 1−3 are measured with a pulsed laser at a wavelength of 1064 nm. Upon irradiation, the microcrystalline sample of complexes emits green light at a wavelength of 532 nm. The SHG optical experimental result indicates that complexes 1−3 are all SHG-active, the efficiencies of which are about 0.5 and 0.3 times, respectively, as much as that of urea. Interestingly, seldom do Co-based coordination polymers exhibit SHG activities. d10 metal ions are commonly used for the construction of coordination polymers with SHG activities to avoid the d−d transitions in the visible region.65 Accordingly, transparent complexes 1 and 2 with Zn2+ and Cd2+ as connecting metals show better SHG properties than that of complex 3 built by Co2+. The SHG efficiency of the crystal ligand H2cpfa is about 0.8 times as much as that of urea; however, after coordination with metals Zn, Cd, and Co, the SHG efficiencies decreased to approximately 0.3−0.5 times as much as that of urea (Table 2). As shown in the literature, some organic compounds could also be SHG-active.66 It is also reported that the SHG

dimensional (3D) supramolecular structure. If we consider the [Zn(cpca)] ring as a eight-connected node and H2O as a fourconnected node, the 3D supramolecule can be simplified as a (4,8)-connected sq22 topological structure with a point symbol of (32.54)(3·44.510.610).63 PXRD Patterns, Thermalgravimetric Analysis, and Circular Dichroism. PXRD and TGA were carried out to investigate the phase purity and stability of these complexes. The peak positions of the experimental and simulated PXRD patterns are in good agreement with each other, indicating that the crystal structures are truly representative of the bulk crystal products. The differences in intensity may be owing to the preferred orientation of the crystal samples (as shown in Figure S4). In order to investigate the stability of the compounds, their thermal behaviors were studied by TGA. The experiments were performed on samples consisting of numerous single crystals of complexes 1−3 under air atmosphere in the temperature range 50−800 °C with a heating rate of 10 °C/min. As shown in Figure S5, complex 1 has two steps of weight losses. The first weight loss of 6.46% in the range of 100−170 °C is consistent with the removal of two coordination water molecules and one lattice water molecule (calcd. 6.33%). The second step of 360− 540 °C can be attributed to the release of cpca2− anions (found, 76.82%; calcd, 78.37%). Complex 2 also has two steps of weight losses. The first weight loss of 5.46% in the range of 100−150 °C could be attributed to the removal of two coordination water molecules and one lattice water molecule (calcd. 5.72%). The second step from 320−560 °C corresponds to the release of cpca2− anions (found, 68.88%; calcd, 70.90%). D



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Luminescent and Sensing Studies. Luminescent properties of metal−organic complexes have been widely investigated, owing to their potential applications in chemical sensors, photochemistry, and electroluminescent displays. In this work, luminescent properties of H2cpca and complexes 1−3 were investigated (Figure 6).

Table 2. SHG Activities of the Ligand H2cpca and Complexes 1−3 compounds H2cpca (powder) H2cpca (crystallize) 1 2 3

chemical formula

dimension

space group

C16H13ClO6 C16H13ClO6

0D

C2221

[Zn(cpca)(H2O)]2· (H2O) [Cd(cpca)(H2O)]2· (H2O) [Co(cpca)(H2O)]2· (H2O)

2D

C2

2D

C2

2D

C2

SHG 0.4× urea 0.8× urea 0.5× urea 0.5× urea 0.3× urea

performance of the crystalline compounds might be different from that of their powder. And the SHG property is also greatly affected by the size and the orientation of the dipole moment of the SHG-active units in the acentric structure. In our investigation, the SHG efficiency of the crystalline organic ligand is higher than that of the powdered one, probably owing to the particle size-dependency of SHG intensity.67,68 Influence of Metal Ionic Radii on the Pore Size of the Complexes. The metal ionic radii could influence the dimensionality and the formation of final architecture since the adoptability of bulkiness in the metal coordination sphere based on the ionic radii directs the coordination modes and connectivity patterns of the linkers.69 It was also reported that the isostructural MOFs based on metals with different ionic radii also demonstrate different functional activities such as different gas adsorption characteristics. 70 However, no conclusion could made about the exact effect of metal ionic radii on the structure and performance of the complexes. We tried to correlate the formation of pore size with different ionic radii of the metal ions used in this study. We employed Zn(II) ions and cpca2− anions building a double-layer CCP {[Zn(cpca)(H2O)]2·H2O}n (1), with a total effective free volume of 41.5 Å3 per cell (2.4% of the crystal volume) by PLATON analysis.71,72 In complexes 2 and 3, the metal center was replaced by Cd(II) ion or Co(II) ion respectively in the same cpca2− anions coordination matrix. When Cd(II) ions were adopted as the metal node, a bigger free volume of 83.7 Å3 per cell (4.6% of the crystal volume) was obtained. However, when employing Co(II) ions with ionic radii similar to that of Zn(II), a similar free volume of 40.0 Å3 per cell (2.3% of the crystal volume) was achieved (Table 3).

Figure 6. Solid-state emission spectra of ligand and complexes 1−3.

The main emission peak of the free ligand H2cpca is at 364 nm (λex = 320 nm), probably attributable to the π* → π transitions. Complexes 1−3 exhibit emission peaks at 367 nm (λex = 285 nm), 351 nm (λex = 295 nm), and 402 nm (λex = 350 nm) respectively as shown in Figure 6. In general, luminescence can arise from direct organic ligands excitation (particularly from the highly conjugated ligands), metal-centered emission (widely observed in lanthanide MOFs through the so-called antenna effect), and charge-transfer such as ligand-to-metal charge transfer (LMCT) and metal-to-ligand charge transfer (MLCT).73 The results indicate that the emissions of complexes 1−3 may originate from the ligand-centered transitions aroused by the π* → π transitions of the intraligands, and their slight shifts might be caused from a coordinative effect.74 In our investigation, it was found that the luminescence of complex 1 could be quenched by nitrobenzaldehyde. When the molar concentration of 4-nitrobenzaldehyde (4-NBA) is 8 mM (1208 ppm), more than 98% luminescent quenching rate of complex 1 can be achieved. It was reported in 2013 that the fluorescence intensity of the suspension of a 2D coordination polymer based on metal Zn and bis(3,5-dicarboxyphenyl)terephthalamide was decreased by 90% with an additional amount of nitrobenzene of 2000 ppm. Compared with this result, complex 1 seems to be more sensitive to the aromatic nitrocompounds.75 We tried to calculate the quenching effect by the Stern−Volmer equation: I0/I = 1 + KSV[M]; however, KSV is not a constant (Figure 7, Table 4). Incorporating a purple emitter of the H2cpca ligand, complex 1 (0.5 mM) exhibited bright emission at about 367 and 383 nm. As shown in Figure 8, not only could 4-nitrobenzaldehyde (4-NBA) quench the luminescence of complex 1, but also 3nitrobenzaldehyde (3-NBA) or 2-nitrobenzaldehyde (2-NBA) have an obvious quenching effect; however, 3-NBA and 2-NBA exhibit a weaker quenching effect to complex 1 compared with 4-NBA. Similarly, the luminescence of complexes 2 and 3 could also be quenched by 4-NBA; however, the emission intensities of complexes 1−3 decrease in different degrees (Figure 9). Similar luminescence quenching abilities toward the complexes have also been found to occur to nitrobenzene

Table 3. Influence of Metal Ionic Radii on the Pore Size of the Complexes entry metal 1 2 3

Zn Cd Co

ionic radii (ppm)

density (g/cm3)

porosity (%)

free volume (cm3/g)

74 97 74

1.639 1.742 1.618

2.4 4.6 2.3

0.015 0.026 0.014

Accordingly, coordination polymers with different free volumes could be obtained by employing metals with different radii sizes. In another words, the ionic radii of the central metal could influence the free volumes of coordination polymers. However, this rule does not tell the whole story about the free volumes of coordination polymers, since the influence of ionic radii can be ignored when the free volumes are big enough. E



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Figure 9. Emission spectra of complexes 1−3 suspension in MeOH upon addition of 4-NBA of 8 mM. The inset showing the magnified emission spectra of complexes 1−3 upon addition of 4-NBA with excitation at 285 nm.

Figure 7. Emission spectra of complex 1 suspension in MeOH with different 4-nitrobenzaldehyde concentrations. The inset showing the relationship between the quenching rate (Y%) and molar concentration of 4-NBA with excitation at 285 nm. The quenching rate is rationalized by the following equation: Y% = (I0 − I)/I0 × 100.

complexes to NBA leading to the luminescence quenching of the complexes.76,77 From the description above, it is found that the complexes built by metal ions of different groups have different abilities to recognize 4-NBA: 1 ≈ 2 > 3. As PLATON analysis shown, the pore size of complex 2 is twice than that of complex 1; however, they have similar ability to recognize 4-NBA. It is assumed that 4-NBA acts with metal ions in the surface of complexes, and the pore sizes of the complexes have little effect on the process. Complex 1 exhibits a better ability to recognize 4-NBA compared to complex 3 with a similar pore size, which may due to the different electronic effects of metals in the complexes. Complexes 1−3 may have potential molecular recognizing applications to aromatic nitro compounds. Catalytic Properties of Complexes 1−3 toward Henry Reactions. From the previous investigation, it is found that certain electrons transfer from the complexes to nitro benzaldehyde may occur to quench the luminescence of complexes 1−3 with the addition of nitrobenzaldehyde. As papers have reported before, complexes 1−3 may have a certain ability to catalyze the nucleophilic reactions of nitrobenzaldehyde.78,79 In the previous reports about asymmetric catalysis, most of the chiral coordination polymers involved are with big free volumes. Lin and his group designed and obtained some chiral porous coordination networks which demonstrate excellent enatioselective activities.80,81 It was also assumed that the pore size played an important role in the catalytic process; however, the reports for chiral coordination polymers with small free volumes or those without channels are rare. In general, Henry reactions would not occur in the absence of the catalysts. In order to explore the heterogeneous asymmetric catalytic activities of complexes 1−3, Henry reaction was selected as the probe reaction, and the influence of solvents on the reaction yield and enantiomeric excess (e.e. value) are investigated (Table 5). Normally, polar protic solvents accelerate the reaction with observed reaction yield in the following order: MeOH > EtOH > THF > CH2Cl2 > toluene. However, the Henry reaction did not occur when water was used as the solvent since the aromatic aldehydes cannot dissolve very well in water. In order to further explore the influence of central metal and the pore size of the complexes on the catalytic activity, complexes 1−3 were employed as catalysts to catalyze the

Table 4. Relationship of Y% and KSV with Different Molar Concentrations of 4-NBA entry

V4‑NBA /μL

[4-NBA]/ mM

I0

I

I0/I

Y%

KSV/M−1

1 2 3 4 5 6 7 8 9

200 300 400 500 600 700 800 900 1000

2.35 3.33 4.21 5.00 5.71 6.36 6.96 7.50 8.00

686 686 686 686 686 686 686 686 686

292 176 102 70 43 32 21 17 13

2.35 3.90 6.73 9.80 15.95 21.44 32.67 40.35 52.77

57.43 74.34 85.13 89.79 93.73 95.33 96.94 97.52 98.10

574 871 1361 1760 2618 3214 4550 5247 6471

Figure 8. Emission spectra of complex 1 suspension in MeOH with 4NBA, 3-NBA, and 2-NBA of 8 mM. The inset showing the magnified emission spectra of complex 1 upon addition of 3-NBA and 2-NBA with excitation at 285 nm.

and cyanobenzene. As indicated in the previous literature, the mechanism of fluorescence sensing can be attributed to the photoinduced electron transfer from an excited complex to the electron-deficient nitrobenzene adsorbed on the surface of the complex through interspecies contacts. The electron-poor aromatic NBA can obtain an electron from the excited ligand, and the excited state electrons are transferred from the F



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Table 5. Henry Reactions Results Catalyzed by Complex 1 in Different Solvents entry

solvents

yielda (%)

e.e. valueb (%)

1 2 3 4 5 6

H2O toluene CH2Cl2 THF EtOH MeOH

trace 60 30 63 75 89

20 15 13 19 21

Table 8. Henry Reactions Results Catalyzed by Complexes 1 for Different Substrates

a

Yield based on aldehydes. be.e. values were determined by HPLC, and the configuration was assigned as R by comparison of the optical rotation with the values from the literature.82

Henry reaction in methanol. The results suggested that complexes 1−3 were able to catalyze the Henry reaction with the activity order as 1 ≈ 2 > 3 (Table 6), which indicates that the central metal instead of the pore size plays important role in the heterogeneous catalytic process.

a


substituted aldehyde has the biggest steric effect toward the nucleophilic addition reaction; however, para- substituted aldehyde shows the smallest steric effect, which is consistent with the above experimental results. It is also proposed that the catalytic process occurred in the surface of the complex, and metal ions acted as the catalytic centers. Noticeably, the effects of the structure of the complexes on the catalytic activity are synergetic and complicated; it is not possible to suggest the exact relationship between the catalytic activity and the structure of the complexes at the current stage. Further studies are being conducted in our successive work. For all of the products for the Henry reaction (1H NMR and HPLC), see Figures S7 and S8).

Table 6. Henry Reactions Results Catalyzed by Complexes 1−3 entry

catalyst

metal ion

time (h)

yielda (%)

e.e. valueb (%)

1 2 3

complex 1 complex 2 complex 3

Zn Cd Co

24 24 24

89 85 71

21 20 13

a


Considering potential application, recovery and recycling efficiency are very important aspects for heterogeneous catalysts. As shown in Table 7, it was found that the yield

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CONCLUSION In summary, we report a new family of three isomorphic chiral coordination polymers with the 1D pseudo-nanotubes in the 2D layer structure built by a chiral dicarboxylic acid named (R)4-(4-(1-carboxyethoxy)phenoxy)-3-chlorobenzoic acid (H2cpca) and transition metal Zn(II), Cd(II), and Co(II) salts. It is found that the ionic radii of the central metal could influence the free volumes of coordination polymers. The complexes 1−3 have different medium second-order nonlinear optical activities, in which the complex 3 is the Co-based coordination polymers with SHG activities. Complexes 1−3 could serve as candidates for recognizing nitroaromatic aldehydes, the luminescence of which could be quenched by nitrobenzaldehyde. The three complexes also exhibit different heterogeneous asymmetric catalytic activities toward Henry reactions. The experimental results indicate that the metal centers instead of the pores in the coordination polymers play a key role in the catalytic processes.

Table 7. Henry Reactions Results Catalyzed by Complex 1 entry

times

time (h)

yielda (%)

e.e. valueb (%)

1 2 3 4 5

1 2 3 4 5

24 24 24 24 24

89 90 85 91 87

21 18 20 21 20

a


and e.e. value of the reaction changed little after complex 1 was used five times as the catalyst. At the same time, PXRD was also used to check the structure stability of complexes 1−3 (Figure S6). We found that the structures of complexes 1−3 remained unchanged after being used five times in the catalytic processes. As shown in Table 8, the dosage of 10% of complex 1 in a molar ratio leads to a 89% yield of 4-NBA. However, yields of only 73% and 60% are achieved for 3-NBA and 2-NBA, respectively. Many relevant reports suggested that this phenomenon may be caused by the channel selectivity. However, the pores in complex 1 are too small for nitrobenzaldehyde molecules to get inside. We assume that the different results achieved from the three substrates may be caused by the steric hindrance of the ortho-, meta- and parasubstitution effect toward the nucleophilic addition reaction of the carbonyl group instead of the channel selectivity. Ortho-

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.cgd.6b00593. Tables S1−S2 and Figures S1−S9 (PDF) Accession Codes

CCDC 1426284−1426287 contain 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 G



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(24) Fu, D. W.; Zhang, W.; Xiong, R. G. Cryst. Growth Des. 2008, 8, 3461. (25) Tang, Y. Z.; Zhou, M.; Huang, J.; Tan, Y. H.; Wu, J. S.; Wen, H. R. Inorg. Chem. 2013, 52, 1679. (26) Zhang, M.; Xue, X. D.; Zhang, J. H.; Xie, S. M.; Zhang, Y.; Yuan, L. M. Anal. Methods 2014, 6, 341. (27) Das, M. C.; Guo, Q. S.; He, Y. B.; Kim, J.; Zhao, C. G.; Hong, K. L.; Xiang, S. C.; Zhang, Z. J.; Thomas, K. M.; Krishna, R.; Chen, B. L. J. Am. Chem. Soc. 2012, 134, 8703. (28) Li, Z. J.; Yao, J.; Tao, Q.; Jiang, L.; Lu, T. B. Inorg. Chem. 2013, 52, 11694. (29) Xie, S. M.; Zhang, Z. J.; Wang, Z. Y.; Yuan, L. M. J. Am. Chem. Soc. 2011, 133, 11892. (30) Liu, B. Y.; Xuan, W. M.; Cui, Y. Adv. Mater. 2010, 22, 4112. (31) Yoon, M.; Srirambalaji, R.; Kim, K. Chem. Rev. 2012, 112, 1196. (32) Ma, L. Q.; Abney, C.; Lin, W. B. Chem. Soc. Rev. 2009, 38, 1248. (33) Seo, J. S.; Whang, D.; Lee, H.; Jun, S. I.; Oh, J.; Jeon, Y. J.; Kim, K. Nature 2000, 404, 982. (34) Falkowski, J. M.; Liu, S.; Lin, W. B. Isr. J. Chem. 2012, 52, 591. (35) Das, M. C.; Xiang, S. C.; Zhang, Z. J.; Chen, B. L. Angew. Chem., Int. Ed. 2011, 50, 10510. (36) Wu, C. D.; Hu, A. G.; Zhang, L.; Lin, W. B. J. Am. Chem. Soc. 2005, 127, 8940. (37) Dang, D. B.; Wu, P. Y.; He, C.; Xie, Z.; Duan, C. Y. J. Am. Chem. Soc. 2010, 132, 14321. (38) Cho, S. H.; Ma, B. Q.; Nguyen, S. T.; Hupp, J. T.; AlbrechtSchmitt, T. E. Chem. Commun. 2006, 2563. (39) Wang, M.; Xie, M. H.; Wu, C. D.; Wang, Y. G. Chem. Commun. 2009, 2396. (40) Gascon, J.; Corma, A.; Kapteijn, F.; Xamena Llabrés i Xamena, F. ACS Catal. 2014, 4, 361. (41) Zhu, W. T.; He, C.; Wu, P. Y.; Wu, X.; Duan, C. Y. Dalton Trans. 2012, 41, 3072. (42) Banerjee, M.; Das, S.; Yoon, M.; Choi, H. J.; Hyun, M. H.; Park, S. M.; Seo, G.; Kim, K. J. Am. Chem. Soc. 2009, 131, 7524. (43) Jones, S. C.; Bauer, C. A. J. Am. Chem. Soc. 2009, 131, 12516. (44) Garibay, S. J.; Wang, Z. Q.; Tanabe, K. K.; Cohen, S. M. Inorg. Chem. 2009, 48, 7341. (45) Liu, L.; Zhang, X.; Rang, S. M.; Yang, Y.; Dai, X. P.; Gao, J. S.; Xu, C. M.; He, J. RSC Adv. 2014, 4, 13093. (46) Peng, Y. W.; Gong, T. F.; Cui, Y. Chem. Commun. 2013, 49, 8253. (47) Regati, S.; He, Y. B.; Thimmaiah, M.; Li, P.; Xiang, S. C.; Chen, B. L.; Zhao, C. G. Chem. Commun. 2013, 49, 9836. (48) Han, Q. X.; He, C.; Zhao, M.; Qi, B.; Niu, J. Y.; Duan, C. Y. J. Am. Chem. Soc. 2013, 135, 10186. (49) Falkowski, J. M.; Sawano; Zhang, T. T.; Tsun, G.; Chen, Y.; Lockard, J. V.; Lin, W. B. J. Am. Chem. Soc. 2014, 136, 5213. (50) Wu, C. D.; Hu, A. G.; Zhang, L.; Lin, W. B. J. Am. Chem. Soc. 2005, 127, 8940. (51) Peng, Y. W.; Gong, T. F.; Cui, Y. Chem. Commun. 2013, 49, 8253. (52) Gedrich, K.; Heitbaum, M.; Notzon, A.; Senkovska, I.; Gedrich, K.; Heitbaum, M.; Notzon, A.; Senkovska, I.; Frö hlich, R.; Getzschmann, J.; Mueller, U.; Glorius, F.; Kaskel, S. Chem. - Eur. J. 2011, 17, 2099. (53) Wu, P. Y.; He, C.; Wang, J.; Peng, X. J.; Li, X. Z.; An, Y. L.; Duan, C. Y. J. Am. Chem. Soc. 2012, 134, 14991. (54) Evans, O. R.; Ngo, H. L.; Lin, W. B. J. Am. Chem. Soc. 2001, 123, 10395. (55) Ma, L. Q.; Wanderley, M. M.; Lin, W. B. ACS Catal. 2011, 1, 691. (56) Huang, Y. B.; Liu, T. F.; Lin, J. X.; Lu, J.; Lin, Z. J.; Cao, R. Inorg. Chem. 2011, 50, 2191. (57) Hou, Y. L.; Sun, W. Y.; Zhou, X. P.; Wang, J. H.; Li, D. Chem. Commun. 2014, 50, 2295. (58) Manna, P.; Tripuramallu, B. K.; Das, S. K. Cryst. Growth Des. 2014, 14, 278.

Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Authors

*(G.-F.H.) Tel.: +86 451 86609001. Fax: +86 451 86609151. E-mail: [email protected]. *(J.-S.G.) E-mail: [email protected]. 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. 21371052 and 21501050), Heilongjiang Postdoctoral Scientific Research Foundation (LBH-Q14138), and Natural Science Foundation Heilongjiang University (QL201307).

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REFERENCES

(1) Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M. Science 2013, 341, 974. (2) Zhu, Q. L.; Xu, Q. Chem. Soc. Rev. 2014, 43, 5468. (3) Furukawa, H.; Ko, N.; Go, Y. B.; Aratani, N.; Choi, S. B.; Choi, E.; Yazaydin, A.; Snurr, R. Q.; O’Keeffe, M.; Kim, J.; Yaghi, O. M. Science 2010, 329, 424. (4) Hwang, I. H.; Bae, J. M.; Hwang, Y. K.; Kim, H. Y.; Kim, C.; Huh, S.; Kim, S. J.; Kim, Y. Dalton Trans. 2013, 42, 15645. (5) Wang, C.; Liu, D. M.; Lin, W. B. J. Am. Chem. Soc. 2013, 135, 13222. (6) Hawes, C. S.; Nolvachai, Y.; Kulsing, C.; Knowles, G. P.; Chaffee, A. L.; Marriott, P. J.; Batten, S. R.; Turner, D. R. Chem. Commun. 2014, 50, 3735. (7) Hou, G. F.; Li, H. X.; Li, W. Z.; Yan, P. F.; Su, X. H.; Li, G. M. Cryst. Growth Des. 2013, 13, 3374. (8) Liu, Y. F.; Hou, G. F.; Yu, Y. H.; Yan, P. F.; Li, J. Y.; Li, G. M.; Gao, J. S. Cryst. Growth Des. 2013, 13, 3816. (9) Tan, Y. Q.; Liu, M.; Gao, J. K.; Yu, J. C.; Cui, Y. J.; Yang, Y.; Qian, G. D. Dalton Trans. 2014, 43, 8048. (10) Farrusseng, D.; Aguado, S.; Pinel, C. Angew. Chem., Int. Ed. 2009, 48, 7502. (11) Manna, K.; Zhang, T.; Lin, W. B. J. Am. Chem. Soc. 2014, 136, 6566. (12) Yi, X. C.; Huang, M. X.; Qi, Y.; Gao, E. Q. Dalton Trans. 2014, 43, 3691. (13) Karmakar, A.; Guedes da Silva, M. F. C.; Pombeiro, A. Dalton Trans. 2014, 43, 7795. (14) Hou, G. F.; Wang, X. D.; Yu, Y. H.; Gao, J. S.; Wen, B.; Yan, P. F. CrystEngComm 2013, 15, 249. (15) Parshamoni, S.; Sanda, S.; Jena, H. S.; Konar, S. Dalton Trans. 2014, 43, 7191. (16) Wu, P. Y.; Wang, J.; Li, Y. M.; He, C.; Xie, Z.; Duan, C. Y. Adv. Funct. Mater. 2011, 21, 2788. (17) Li, B. Y.; Zhang, Y. M.; Li, G. H.; Liu, D.; Chen, Y.; Hu, W. W.; Shi, Z.; Feng, S. H. CrystEngComm 2011, 13, 2457. (18) Lin, L.; Yu, R. M.; Yang, W. B.; Wu, X. Y.; Lu, C. Z. Cryst. Growth Des. 2012, 12, 3304. (19) Yang, X. L.; Wu, C. D. CrystEngComm 2014, 16, 4907. (c) He, W. W.; Yang, J.; Yang, Y.; Liu, Y. Y.; Ma, J. F. Dalton Trans. 2012, 41, 9737. (20) Banerjee, S.; Adarsh, N. N.; Dastidar, P. CrystEngComm 2009, 11, 746. (21) Wu, B. L.; Wang, S.; Wang, R. Y.; Xu, J. X.; Yuan, D. Q.; Hou, H. W. Cryst. Growth Des. 2013, 13, 518. (22) Zhang, H. T.; Li, Y. Z.; Wang, T. W.; Nfor, E. N.; Wang, H. Q.; You, X. Z. Eur. J. Inorg. Chem. 2006, 2006, 3532. (23) Chen, M.; Lu, Y.; Fan, J.; Lv, G. C.; Zhao, Y.; Zhang, Y.; Sun, W. Y. CrystEngComm 2012, 14, 2015. H



Article

(59) Sheldrick, G. M. Acta Crystallogr., Sect. A: Found. Crystallogr. 2008, 64, 112. (60) Cheetham, A. K.; Rao, C. N. R.; Feller, R. K. Chem. Commun. 2006, 4780. (61) Lin, J. D.; Wu, S. T.; Li, Z. H.; Du, S. W. CrystEngComm 2010, 12, 4252. (62) Chen, S. C.; Zhang, Z. H.; Zhou, Y. S.; Zhou, W. Y.; Li, Y. Z.; He, M. Y.; Chen, Q.; Du, M. Cryst. Growth Des. 2011, 11, 4190. (63) Blatov, V. A.; Shevchenko, A. P.; Serezhkin, V. N. J. Appl. Crystallogr. 2000, 33, 1193. (64) Kurtz, S. K.; Perry, T. T. J. Appl. Phys. 1968, 39, 3798. (65) Ye, H. T.; Ren, C. Y.; Hou, G. F.; Yu, Y. H.; Xu, X.; Gao, J. S.; Yan, P. F.; Ng, S. W. Cryst. Growth Des. 2014, 14, 3309. (66) Wang, C.; Zhang, T.; Lin, W. B. Chem. Rev. 2012, 112, 1084. (67) Yang, H.; Sang, R. L.; Xu, X.; Xu, L. Chem. Commun. 2013, 49, 2909. (68) Liu, G. N.; Zhang, M. J.; Liu, W. Q.; Sun, H.; Li, X. Y.; Li, K.; Ren, C. Z.; Zhang, Z. W.; Li, C. C. Dalton Trans. 2015, 44, 18882. (69) Manna, P.; Tripuramallu, B. K.; Das, S. K. Cryst. Growth Des. 2014, 14, 278. (70) Mishra, P.; Edubilli, S.; Mandal, B.; Gumma, S. J. Phys. Chem. C 2014, 118, 6847. (71) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7. (72) Spek, A. L. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2009, 65, 148. (73) Cui, Y. J.; Yue, Y. F.; Qian, G. D.; Chen, B. L. Chem. Rev. 2012, 112, 1126. (74) Li, S. L.; Lan, Y. Q.; Qin, J. S.; Ma, J. F.; Liu, J.; Yang, J. Cryst. Growth Des. 2009, 9, 4142. (75) Wang, G. Y.; Yang, L. L.; Li, Y.; Song, H.; Ruan, W. J.; Chang, Z.; Bu, X. H. Dalton Trans. 2013, 42, 12865. (76) Zheng, Q. S.; Yang, F. L.; Deng, M. L.; Ling, Y.; Liu, X. F.; Chen, Z. X.; Wang, Y. H.; Weng, L. H.; Zhou, Y. M. Inorg. Chem. 2013, 52, 10368. (77) Kim, T. K.; Lee, J. H.; Moon, D.; Moon, H. R. Inorg. Chem. 2013, 52, 589. (78) Jiao, Y.; Wang, J.; Wu, P. Y.; Zhao, L.; He, C.; Zhang, J.; Duan, C. Y. Chem. - Eur. J. 2014, 20, 2224. (79) Wu, X.; Lin, Z. H.; He, C.; Duan, C. Y. New J. Chem. 2012, 36, 161. (80) Wu, C. D.; Hu, A. G.; Zhang, L.; Lin, W. B. J. Am. Chem. Soc. 2005, 127, 8940. (81) Ma, L. Q.; Abney, C.; Lin, W. B. Chem. Soc. Rev. 2009, 38, 1248. (82) Kanagaraj, K.; Suresh, P.; Pitchumani, K. Org. Lett. 2010, 12, 4070.

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Synthesis, Structure, and Properties of a Series of Chiral Coordination

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