Homochiral Porous Metal-Organic Frameworks Constructed from a V

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Homochiral Porous Metal-Organic Frameworks Constructed from a V-Shaped Alanine Derivative Based on Pyridyl-Dicarboxylate Qi Yue, Wei-Xiao Guo, Yuan-Yuan Wang, Xiao-Lu Hu, and En-Qing Gao Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.9b00152 • Publication Date (Web): 16 Mar 2019 Downloaded from http://pubs.acs.org on March 17, 2019

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Crystal Growth & Design

Homochiral Porous Metal-Organic Frameworks Constructed from a V-Shaped Alanine Derivative Based on Pyridyl-Dicarboxylate

Qi Yue*, Wei-Xiao Guo, Yuan-Yuan Wang, Xiao-Lu Hu and En-Qing Gao

School of Chemistry and Molecular Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, East China Normal University, Shanghai 200241, P.R. China

KEYWORDS: Homochiral MOFs, porosity, alanine derivative, pyridyl-dicarboxylate, CO2 adsorption.

ACS Paragon Plus Environment

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ABSTRACT

Three novel homochiral porous MOFs based on the H2PDBAla ligand and different divalent cations (Co(II)) and Cu(II)), namely [M(PDBAla)(bipy)(H2O)2]∙3H2O (M = Co 1 and Cu 2), [Cu(PDBAla)(bpea)]∙7H2O (3) (H2PDBAla = pyridine-2,6-dicarbonyl-bis(L-alanine), bipy = 4,4'bipyridine, bpea = 1,2-bis(4-pyridyl)ethane), have been synthesized and characterized in the assistance of N-donor ligands. The distinctive H2PDBAla ligands are coordinated to divalent metal ions by the different coordination modes, forming various helixes in compounds 1-3. Compounds 1 and 2 are isostructural and feature a 2-fold interpenetrating 3D framework with the cds topological net built by the combination right-handed helical chains and bipy ligands, whereas a 3D framework with the tcj topological net is observed in compound 3, wherein bpea ligands reinforce the 3D framework constructed by right-handed helical chains. Compounds 1 and 3 display high CO2 absorption capability and superior sorption enthalpies, reflecting the strong affinity of the frameworks for CO2. Moreover, compound 3 exhibits a small enantioselective separation performance for racemic alcohol.


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INTRUDUCTION Homochiral porous metal-organic frameworks (HPMOFs) as a class of chiral crystalline porous materials combining chirality and porosity have emerged highly promising for the enantioselective resolution of racemic mixture, enantioselective catalysis and recognition, etc.1-18 Therefore, the HPMOFs have been actively developed in recent decade, due to their high stability, large surface area and adjustable functionality, which benefits from varying organic building blocks. Those advantages are surpassing traditional inorganic and organic chiral porous materials. The alteration of chiral linkers not only tailor pore size and flexibility but also affect various functionality of synthesized frameworks. As an ideal chiral ligand, amino acid derivative utilizes low-cost and easy available natural amino acid as chiral source, meantime it enhances the rigidity of natural amino acid. It is an usual synthesized approach for the amino acid derivatives that the polycarboxylates as substitutional groups modify the amino groups of natural amino acids. Currently, the linear,1921

V-shaped18,22-23 and triangular24-27 amino acid derivatives have been researched for the

fabrication of the multifunctional HPMOFs. However, the few HPMOFs incorporating of permanent porosity and intriguing structures are reported.28-30 Using the pyridyl-carboxylate unit instead of common polycarboxylate group to decorate the natural amino acid is rarely been investigated.31-34 Therefore, the application of pyridyl-carboxylate-amino acid derivatives for construction of stable HPMOFs remains an unexplored field and affords great potential owing to diverse coordination patterns and plentiful coordination points in comparison to the usual polycarboxylate-amino acid derivatives. Actually, using different functional pyridine ligand is a very effectively method to change structure and property of framework compounds, not only for MOFs, but also for self-assembled supramolecular coordination complexes.35-38


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Accordingly, we have modified the –NH2 group of alanine with pyridine-2,6-dicarboxylate and designed an enantiopure alanine derivative H2PDBAla (Scheme 1). This distinctive chiral ligand possesses many features: (a) the enantiomeric alanine unit offers the chiral component; (b) the pyridyl-dicarboxylate unit improves the coordination diversity and rigidity of the chiral ligand; (c) the V-shaped coordination configuration of the chiral ligand is very favorable for achievement of the HPMOFs. Meanwhile, owing to the coexistence of L-alanine and pyridyl-dicarboxylate units, the semi-rigid H2PDBAla has the bifunctional groups of the -NH and the -C=O moieties, which furnish two types of guest accessible active sites. The -NH group acts as location of the CO2 adsorption and the -C=O group acts as location of the Lewis base. These features could facilitate to attain stable HPMOFs with attractive architectures and excellent properties. Furthermore, the introducing assistant N-donor ligands into chiral metal-pyridyl-dicarboxylate system should increase the space dimension and stability of HPMOFs. In this work, three novel HPMOFs with helixes have been successfully prepared by using the enantiopure alanine derivative H2PDBAla in the assistance of bipy and bpea ligands, namely two isostructural

[M(PDBAla)(bipy)(H2O)2]∙3H2O

(M

=

Co

1

and

Cu

2)

and

[Cu(PDBAla)(bpea)]∙7H2O (3). The detailed structures of title compounds have been described. The CO2 gas adsorption properties of compounds 1 and 3, as well as the enantioseparation of racemic 1-phenylethyl alcohol for 3 have been investigated.

EXPERIMENTAL SECTION Materials and Methods. All chemical reagents were commercial origin. Thermogravimetric analyses (TGA) were recorded on TGA Q500 V20.10 Build 36 thermogravimetric analyzer from room temperature to 800 °C at a heating rate of 10 °C/min under N2 atmosphere. Solid-state


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Circular dichroism (CD) spectra were carried out on a JASCO J-815 spectrometer. The IR spectra were carried out on a Bruker NicoletiS50 spectrometer (4000-400 cm-1). Elemental analyses were obtained using an Elementar Vario ELIIICHN elemental analyzer. Powder X-ray diffraction (PXRD) studies were performed using a Bruker D8 ADVANCE. CO2 adsorption isotherm were determined on a Micrometrics ASAP 2020 instrument at 195 K, and a Micrometrics ASAP 2020 PLUS HD88 instrument at 273 and 298 K. Synthesis of [Co(PDBAla)(bipy)(H2O)2]∙3H2O (1). A mixture of H2PDBAla (0.0093 g, 0.03 mmol), Co(NO3)2·6H2O (0.0175 g, 0.06 mmol), bipy (0.0094 g, 0.06 mmol), 2 ml H2O and 1 mL N,N'-dimethylformamide (DMF) was placed in a 20 mL scintillation vial and stirred for 30 min at room temperature, the resulting red suspending solution was heated to 90 °C for 48 h. The clear red solution was obtained while vial was cooled to the room temperature. Red square sheet crystals of 1 were finally isolated, when the clear solution slowly were evaporated at room temperature after 1 week (yield, 54 % based on H2PDBAla). Anal. Calc. For C23H31N5O11Co: C, 45.10; H, 5.10; N, 11.44 %. Found: C, 45.15; H, 5.08; N, 11.41 %. IR (KBr, cm-1): 3279(s), 2940(w), 1652(s), 1592(s), 1532(s), 1452(s), 1422(s), 1361(m), 1305(w), 1273(w), 1072(w), 1002(w), 873(w), 812(w), 672(w), 622(w). Synthesis of [Cu(PDBAla)(bipy)(H2O)2]∙3H2O (2). A blue suspension solution including H2PDBAla (0.0093 g, 0.03 mmol), Cu(NO3)2·6H2O (0.0073 g, 0.03 mmol), bipy (0.0094 g, 0.06 mmol), 2 ml H2O and 1 mL N,N-dimethylformamide (DMF) was placed in a 20 mL scintillation vial and stirred for 30 min at room temperature. And then, the final clear blue mixture solution was obtained when the 0.8 mL HNO3 (0.16 mol∙L-1) was put into the above suspension solution. Blue square sheet crystals of 2 were finally isolated, when the clear solution slowly were evaporated at room temperature after 1 week (yield, 27 % based on H2PDBAla). Anal. Calc. For


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C23H31N5O11Cu: C, 44.77; H, 5.06; N, 11.35 %. Found: C, 44.75; H, 5.02; N, 11.36 %. IR (KBr, cm-1): 3390(w), 3279(w), 2942(w), 1652(m), 1612(s), 1533(s), 1453(m), 1412(s), 1392(m), 1361(w), 1291(w), 1222(w), 1182(w), 1072(w),993(w), 873(w), 664(w), 633(w). Synthesis of [Cu(PDBAla)(bpea)]∙7H2O (3). The sodium salt of H2PDBAla (0.0105 g, 0.03 mmol) and bpea (0.0055 g, 0.03 mmol) were dissolved in 3 mL H2O with constant stirring, and Cu(NO3)2∙3H2O (0.0145 g, 0.06 mmol) was dissolved in 3 mL methanol. The 3 mL methanol solution including Cu(NO3)2 was slowly and carefully layered on top of the 3 mL H2O of mixed ligands via the using 6 mL buffer solution of H2O and MeOH (1:1) in a test tube. After two weeks, dark blue block-shaped crystals of 3 were grown on the wall of the tube in the region of buffer solution. Yield: 59 % (based on H2PDBAla). Anal. Calc. For C25H39N5O13Cu: C, 44.08; H, 5.77; N, 10.28 %. Found: C, 44.05; H, 5.73; N, 10.24 %. IR (KBr, cm-1): 3390(w), 2940(w), 2360(w), 1612(s), 1522(s), 1452(m), 1402(s), 1365(m), 1270(w), 1223(w), 1182(w), 1072(w), 1013(w), 862(w), 611(w), 543(w). Single Crystal X-ray Diffraction. X-ray single crystal diffraction data of compounds 1-3 were collected on a Bruker APEX II-CCD diffractometer with graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å) at 298 K. The structures were solved by the direct method and refined by the full-matrix least-squares techniques by means of the SHELXTL-2014 software. Non-H atoms were refined anisotropically. The H atoms of organic ligands were calculated at idealized positions and refined. The H atoms of coordinated H2O molecules were placed from difference Fourier maps. The SQUEEZE routine of PLATON program was employed to move the lattice water of severe thermal disorder in the pores. Compounds were formulated on the basis of the crystallographic data, thermogravimetric and elemental analysis. Crystallographic and structure


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refinement parameters of compounds 1-3 are listed in Table 1. Their main bond lengths and angles are tabled in Table S1-3.

RESULTS AND DISCUSSION Structural description Structure of [M(PDBAla)(bipy)(H2O)2]·3H2O (M = Co, 1 and Cu, 2). Single-crystal X-ray diffraction reveals that compounds 1 and 2 are isostructural except for the difference of metal ion, so only the detailed structure of 1 is depicted herein. These crystal structures belong to chiral P4322 space group of tetragonal system and possess a 3D two-fold interpenetrating framework. There are a half Co(II) ion, a half PDBAla2- anion, a half bipy ligand, one coordination and one and half lattice water molecules in the asymmetric unit (Figure 1a). The slightly distorted octahedral geometry of Co(II) center is located at a 2-fold axis and is six-coordinated by two coordinated water molecules (O4 and O4A), two carboxylate oxygen atoms (O1 and O1A) from two PDBAla2anions, and two nitrogen atoms (N3 and N4B) from two bipy ligands. The four oxygen atoms form the equatorial plane and the two nitrogen atoms occupy the axial positions with the N3-Co-N4B angle of 180.0 (0)°. The Co-O bond lengths span from 2.0575(12) to 2.1400(13) Å, and the Co-N bond lengths are 2.1443(19) (Co1-N3) and 2.1517(19) (Co2-N4B) Å. A four-angle star-shaped substructure viewed from the [001] direction is generated, when two carboxylate groups of the PDBAla2- anion adopting the monodentate coordination mode coordinate to two Co(II) ions. This substructure is composed of a single-stranded right-handed {Co-PDBAla} helical chain running along the c-axis. Such helical chain contains four Co(II) ions and four PDBAla2- anions per turn, and it helical pitch of 48.9650(2) Å is identical to the length of the c-axis (Figure 1b). Four adjacent four-angle star-shaped substructures encircle around


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central one to present a circular pattern observed from the c-axis, because of the presence of 26.474° dihedral angle between the two amide groups and the center pyridine ring in the helical chain. Interestingly, two nitrogen atoms of the amide groups and one nitrogen atom of the pyridine ring from one PDBAla2- anion define an uncoordinated chelating site (UCS) in the helical chain. The {Co-PDBAla} helical chains arranged in parallel with each other are further interlinked by the bipy ligands bridging Co(II) ions to create a HPMOF with large chiral channels (Figure 1c). It is worth noting that the uncoordinated chelating sites (UCSs) are regularly lined on the porous surface. Moreover, the –NH groups, the carbonyl O atoms and the uncoordinated carboxylate O atoms on the pore wall point toward the channels. These active sites could supply effective interactional positions for guest molecules to enhance adsorption ability of the framework for guest molecules. Topologically, Co(II) can be described as 4-connected node, and PDBAla2- anion and bipy ligand are regarded as simple linker, the single framework of 1 can be represented as a cds topological net with the Schläfli symbol of (65.8) (Figure S1). It is noteworthy that the large chiral interconnected void spaces exist in the single 3D framework of 1. The rectangular window has channel cross sections of about 16.98 Å × 16.46 Å, measured between two nearest Co(II) ions from diagonal positions. The V-shaped window has a distance of about 9.60 Å, measured between the nearest C and N atoms from two sharp-angled positions observed down the [100] and [010] directions (Figure 1d). The larger wave-like window has an edge-to-edge average distance of about 11.38 Å, measured between two nearest Co(II) ions from opposite edges observed along the [110] direction (Figure 1e). The van der Waals radius of the atoms have not taken into account when estimating the dimensions of the channels. The large void spaces are enough to accommodate another independent equivalent framework, resulting in a 2fold interpenetrated 3D architecture (Figure 2b). After the mutual interpenetration, the wave-like


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windows from two single frameworks are filled to each other in a parallel fashion observed along the [110] direction (Figure 2a), but the rectangular and V-shaped windows of two single frameworks are overlapped together observed along the [100] and [010] directions (Figure 2c). Fortunately, the final framework retains the rectangular and V-shape open chiral channels, although the interpenetration blocks the wave-like voids. Calculation using PLATON program gives the effective available volume of 29.5 % per unit cell for three lattice water molecules. Structure of [Cu(PDBALa)(bpea)]·7H2O (3). Compound 3 is crystallized in tetragonal system with chiral space group of P41. One Cu(II) ion, one PDBAla2- anion, one bpea ligand and seven lattice water molecules form the asymmetric unit of 3. As depicted in Figure 3a, the Cu(II) ion poses a slightly twisted square-pyramidal coordination environment {CuN2O3}, the base plane of the pyramid is comprised of two nitrogen atoms (N4 and N5B) from two bpea ligands and two carboxylate oxygen atoms (O1 and O6C) from two different PDBAla2- anions, and the axial position is occupied by one carbonyl oxygen atom (O4A) of the amide group from PDBAla2- anion. The Cu-O bond lengths range from 1.938(3) to 2.347(3) Å, and the Cu-N bond lengths are 2.038(3) and 2.060(3) Å. Different from the coordination manner of the PDBAla2- anion in 1, the PDBAla2- anion of 3 captures three Cu(II) ions via its two carboxylate groups adopting monodentate bridging mode and one carbonyl oxygen atom of amide group. Due to the unique coordination manner of the PDBAla2anion, a 3D {Cu-PDBAla} framework is achieved. Just like the compound 1, the uncoordinated chelating sites (UCSs) defined by the three nitrogen atoms also are equipped in the skeleton of 3, whereas two amide groups and the center pyridine ring are almost coplanar and have the dihedral angles of 1.481° and 3.067°, respectively. As illustrated in Figure 3b, the PDBAla2- fragments bridge the Cu(II) ions into a propeller-shaped single-stranded right-handed helical chain running


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along the c-axis. This fragment is made up of one amide group, one pyridine ring and one alanine unit of the PDBAla2- anion. Each helical chain includes four Cu(II) ions and four PDBAla2fragments per turn and its helical pitch of 19.0000 Å equals to the length of the c-axis. The neighboring helical chains are further integrated together to each other by another alanine units of the PDBAla2- anions, which are coordinated with the Cu(II) ions of the adjacent helical chains to develop a 3D {Cu-PDBAla} framework with 1D open chiral channels along the c-axis (Figure 3c). The square window of the chiral channel has a separation of about 13.2595(10) Å including van der Waals radius, measured between two nearest Cu(II) ions from opposite edges. In the framework 3, both PDBAla2- anions and Cu(II) ions can be taken as the 3-connected junctures and thus the {Cu-PDBAla} 3D framework is topologically rationalized as a ThSi2 net with a Schläfli symbol of (103) (Figure S2a). As linkers, the bpea ligands provide additional connection between the Cu(II) ions of adjacent helical chains to reinforce the stability of 3D {Cu-PDBAla} framework, but reduce the dimensions of the square windows to a separation of about 6.7728(3) Å (including van der Waals radius) (Figure 3d and 3e). When bpea ligands are simply seen as linkers, Cu(II) ions can be treated as 5-connected nodes, PDBAla2- ligands serve still as 3-connected nodes. Therefore, the overall 3D framework of 3 should be simplified as a (3,5)-connected tcj topological net with a Schläfli symbol of (52.6) (Figure S2b). Particularly, the uncoordinated chelating sites (UCSs), the carbonyl O atoms and the –NH groups of the amide groups are uniformly inserted on the channel surface. These functional groups point toward the chiral channels and should be available for separation of enantiomers and increase of the host-guest interactions. Calculation using PLATON program indicates the total available volume of 31.7 % per unit cell, which is occupied by seven lattice water molecules.


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Circular Dichroism (CD). The CD spectra of free H2PDBAla ligand and title compounds in the solid state have been charactered for further demonstrating their homochiral nature (Figure S3 and S4). The CD spectrum of free H2PDBAla ligand displays strong one positive Cotton peak at 291 nm and one negative Cotton peak at 202 nm. The CD spectra of compounds 1 and 2 exhibit similar Cotton peaks because of their isostructure: for 1, a strong and weaker positive Cotton peaks at 291 and 243 nm, respectively; for 2, a strong and weaker positive Cotton peaks at 309 nm and 241 nm, respectively. The CD spectrum of 3 shows only one strong positive Cotton peak at 295 nm. These enough prove the homochirality of title compounds and agree with the chiral frameworks identified by the single crystal structural analyses. Gas Adsorption Properties. To estimate the permanent porosity of chiral evacuated frameworks, N2 and CO2 gas adsorption isotherms were measured. The gas sorption properties of 1 and 3 are described here in detail because compounds 1 and 2 are isostructural. Prior to gas adsorption experiments, the water molecules in the pores of compounds 1 and 3 were removed by the method of exchanging solvent to obtain the evacuated frameworks 1' and 3'. (see ESI and Figure S5). 1' and 3' only exhibit surface adsorption of N2 at 77K since their aperture sizes are smaller than the kinetic diameter of N2 (Figure S6). The CO2 adsorption of 1' at 195 K exhibits a reversible type I isotherm with a little hysteresis loop (Figure 4a, I), a characteristic of microporous materials. The adsorption amount of CO2 gas is 70.6 cm3·g-1 (13.9 wt % at STP, 3.2 mmol·g-1) at 195 K and 1 atm. The Langmuir and BET surface area are calculated to be 201.3 and 126.3 m²·g1,

respectively. Since two-fold interpenetrated framework of 1 is very stable, the small hysteresis

loop reflects strong affinity of the host framework containing the active interacting sites for CO2 molecules.39 The CO2 adsorption isotherms at 273 and 298 K also show typical type I isotherms,


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as shown in Figure 4a, II and III. At 273 and 298 K, the CO2 uptakes of 1' at 1 atm are 14.4 (2.8 wt %) and 6.7 cm3·g-1 (1.3 wt %), respectively. In contrast to 1', the CO2 adsorption isotherm of 3' at 195 K displays an unusual stepped double S-shaped curve with obvious hysteresis (Figure 4b, I). The surface area calculated from Langmuir and BET equation are 533.6 and 358.7 m²∙g-1, respectively. The whole curve is divided into three steps, and each shows a typical type I profile. The steep increase of the CO2 uptake at very low pressures reveals the existence of intrinsic micropores in 3'.40 The adsorption saturation of the first step occurs at 0.07 atm (A point), where the adsorption amount is 70.5 cm3·g-1 (13.8 wt %). The second step starts at 0.08 atm and ends at 0.55 atm (B point), where the adsorption amount reaches 132.9 cm3·g-1 (26.1 wt %). The third step begins at 0.6 atm with the adsorption amount reaching 157.0 cm3·g-1 (30.8 wt %, 7.0 mmol·g-1) at 1 atm. Notably, the desorption isotherm also displays stepwise profile at the corresponding inflection points of the adsorption isotherm but do not retrace the adsorption route to cause an evident hysteresis loop. In general, stepwise adsorption isotherm and hysteresis loop could be ascribed to strong adsorbate-adsorbent interactions and/or occurrence of gate-opening phenomena related to flexible or dynamic porous frameworks.41-45 Therefore, the stepped CO2 adsorption isotherm of 3' at low temperature could be associated with its structural characters. At 195 K, the first step adsorption of 3' should be attributed to the -NH groups and uncoordinated chelating sites (UCSs) on the pore surfaces, and the second step stems from the expansion of the framework when CO2 molecules fill the channels. It open up the channels and lead to the steep uptake of the adsorbance in the first step of isotherm that the CO2 molecules interact strongly with the framework of 3' by means of those active interactional sites. Owing to the flexibility of the bpea ligand with trans-conformation, the


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dimensions of the window of channel are expanded along with CO2 continually entering the cavity of the framework, giving rise to the second sudden step in the isotherm. While the measured temperature increased to 273 K, the CO2 adsorption isotherm still shows stepwise adsorption stage with a large hysteresis loop (Figure 4b, II). The adsorption amount of initial step is 44.8 cm3·g-1 (8.8 wt %) in the pressure region of 0-0.9 atm. In the next step, the CO2 uptake is 64.6 cm3·g-1 (11.5 wt %) under 1 atm. This stepped adsorption behavior of 3' at 273 K originates from the slight stretch of the flexible bpea ligand when CO2 pressure increases to 0.9 atm.41,46 The other possible reason for large hysteresis loop could be that its structural feature of small window and large chamber brings about a hindrance for CO2 to diffuse out of pores.47 At 298 K, the no stepped CO2 adsorption isotherm is observed (Figure 4b, III). It has type I isotherm and CO2 uptake amounted to be 22.9 cm3·g-1 (4.5 wt %) under 1 atm. For 1' and 3', the distinct CO2 adsorption behaviors at all temperature region could be dependent on their structural differences. The larger void spaces and aperture sizes allow 3' to have higher CO2 adsorption capacity in comparison to 1'. The CO2 isotherms without stepwise profile for 1' and 3' at 298 K are due to the high thermal energy of the frameworks and CO2 molecules decrease their interactions.48 Additionally, the hysteresis loops of CO2 isotherms for 1' and 3' are open. This case could be attributed to the phenomenon of capillary condensation and the incomplete equilibrium during the adsorption process at low temperature and low pressure, because the mobility and diffusion of molecules are slower.49-51 To further estimate the affinity of 1' and 3' for CO2, the adsorption enthalpies (Qst) of CO2 were calculated using the virial model on the basis of the CO2 adsorption isotherms at 273 and 298 K to give 32.5 and 33.3 kJ∙mol-1 near zero coverage, respectively. These values are comparable to reported those of a majority of MOFs with large CO2 adsorption capability (Table S4), suggesting


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strong framework-CO2 interactions.52-56 The possible reason for the high enthalpy (Qst) is the pore surfaces decorated with the –NH groups and uncoordinated chelating sites (UCSs) provide active interacting sites to effectively enhance the host-guest interactions between evacuated frameworks and CO2 molecules. Although 1' and 3' display the large difference in adsorption capacity, they have relatively close adsorption enthalpies. This could mainly due to the affection of these similar active sites. These results confirm that 1' and 3' have permanent porosity and architectural stability and can potentially be used for CO2 separation. Enantioselective Separation. The homochirality and porosity of compounds 1 and 3 prompt us to investigate the enantioselective separation of racemic 1-phenylethyl alcohol. 1' has not enantioseparation ability, which is responsible for none penetration of 1-phenylethyl alcohol along the pore because 1' has the small pore size. 3' exhibits small chiral separation of 1-phenylethyl alcohol with an ee of 8 %, as shown in Figure S7. This relatively low enantioselective arises from the kinetic diameter of the alcohol is larger than the size of the channel window. Thus, it is speculated that the enantioselective separation of 3' could only occur on the chiral surface of the framework through hydrogen bonding, π∙∙∙π stacking interactions and stereochemical interaction of a chiral carbon atom between the aromatic alcohol and surface of the framework.57-59

CONCLUSION Using pyridyl-dicarboxylate unit to replace common polycarboxylate group has been designed a striking alanine derivative, on this basis, constructed desirable HPMOFs 1-3. Three compounds display beautiful 3D frameworks with different topologies built from right-handed helixes and ancillary N-donor ligands. Compounds exhibit high CO2 absorption capability and superior sorption enthalpies, indicating strong interactions between CO2 and frameworks, which benefits


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from the active sites of pore surface arising from the unique alanine derivative. In addition, compound 3 shows a small enantioselective separation ability of racemic alcohol. The design and synthesis of the unique pyridyl-dicarboxylate-based alanine derivative can provide a practicable and effective method for construction of functional HPMOFs with fascinating architectures and properties.

ASSOCIATED CONTENT Supporting Information The supporting information is available free of charge on the ACS Publications website at DOI:10.1021/. Power X-ray diffraction patterns, IR spectra, TGA, CD spectra, enantioselective separation experiments, related structural figures for the compounds, and X-ray crystallographic files of compounds 1-3 in CIF format. Accession Codes CCDC 1891960−1891962 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/data_request/cif, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected].

AUTHOR INFORMATION Corresponding Author * (Qi Yue) E-mail address: [email protected]. Telephone: +86 021 54340062.


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ACKNOWLEDGMENT This work was financially supported by the National Natural Science Foundation of China (NSFC No. 21101064).

REFERENCES (1) Yuan, G. Z.; Jiang. H.; Zhang, L. Y.; Liu. Y.; Cui, Y. Metallosalen-based crystalline porous materials: Synthesis and property. Coordination Chemistry Reviews. 2019, 378, 483-499. (2) Nguyen, K. D.; Kutzscher, C.; Drache, F.; Senkovska, I.; Kaskel, S. Chiral Functionalization of a Zirconium Metal-Organic Framework (DUT-67) as a Heterogeneous Catalyst in Asymmetric Michael Addition Reaction. Inorg. Chem. 2018, 57, 1483-1489. (3) Cheng, W.; Shen, F. C.; Xue, Y. S.; Luo, X.; Fang, M.; Lan, Y. Q.; Xu, Y. A Pair of Rare Three-Dimensional Chiral Polyoxometalate-Based Metal-Organic Framework Enantiomers Featuring Superior Performance as the Anode of Lithium-Ion Battery. ACS Appl. Energy Mater. 2018, 1, 4931-4938. (4) Zhao, X.; Nguyen, E. T.; Hong, A. N.; Feng, P.; Bu, X. Chiral Isocamphoric Acid: Founding a Large Family of Homochiral Porous Materials. Angew. Chem. Int. Ed. 2018, 57, 7101-7105. (5) Chan, J. Y.; Zhang, H.; Nolvachai, Y.; Hu, Y.; Zhu, H.; Forsyth, M.; Gu, Q.; Hoke, D. E.; Zhang, X.; Marriot, P. J.; Wang, H. Incorporation of Homochirality into a Zeolitic Imidazolate Framework Membrane for Efficient Chiral Separation. Angew. Chem. Int. Ed. 2018, 57, 1713017134.


16

Page 17 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(6) Gu, Z. G.; Fu, W. Q.; Wu, X.; Zhang, J. Liquid-phase epitaxial growth of a homochiral MOF thin film on poly(L-DOPA) functionalized substrate for improved enantiomer separation. Chem. Commun. 2016, 52, 772-775. (7) Asnaghi, D.; Corso, R.; Larpent, P.; Bassanetti, I.; Jouaiti, A.; Kyritsakas, N.; Comotti, A.; Sozzani, P.; Hosseini, M. W. Molecular tectonics: gas adsorption and chiral uptake of (L)- and (D)-tryptophan by homochiral porous coordination polymers. Chem. Commun. 2017, 53, 57405743. (8) Zhang, Q.; Lei, M.; Kong, F.; Yang, Y. A water-stable homochiral luminescent MOF constructed from an achiral acylamide-containing dicarboxylate ligand for enantioselective sensing of penicillamine. Chem. Commun. 2018, 54, 10901-10904. (9) Tanaka, K.; Kawakita, T.; Morawiak, M.; Urbanczyk-Lipkowska, Z. A novel homochiral metal-organic framework with an expanded open cage based on (R)-3,3΄-bis(6-carboxy-2naphthyl)-2,2΄-dihydroxy-1,1΄-binaphthyl: synthesis, X-ray structure and efficient HPLC enantiomer separation. CrystEngComm. 2019, 21, 487-493. (10) Tanaka, K.; Kinoshita, M.; Kayahara, J.; Uebayashi, Y.; Nakaji, K.; Morawiak, M.; et al. Asymmetric ring-opening reaction of meso-epoxides with aromatic amines using homochiral metal-organic frameworks as recyclable heterogeneous catalysts. RSC Advances. 2018, 8, 2813928146. (11) Bhattacharjee, S.; Khan, M. I.; Li, X.; Zhu, Q. L.; Wu, X. T.; Recent Progress in Asymmetric Catalysis and Chromatographic Separation by Chiral Metal-Organic Frameworks. Catalysts. 2018, 8, 120.


17


Page 18 of 31

(12) Zhao, X.; Wong, M.; Mao, C.; Trieu , T. X.; Zhang, J.; Feng, P.; et al. Size-Selective Crystallization of Homochiral Camphorate Metal-Organic Frameworks for Lanthanide Separation. J. Am. Chem. Soc. 2014, 136, 12572-12575. (13) Xia, Q.; Li, Z.; Tan, C.; Liu, Y.; Gong, W.; Cui, Y. Multivariate Metal-Organic Frameworks as Multifunctional Heterogeneous Asymmetric Catalysts for Sequential Reactions. J. Am. Chem. Soc. 2017, 139, 8259-8266. (14) Chen, X.; Jiang, H.; Hou, B.; Gong, W.; Liu, Y.; Cui, Y. Boosting Chemical Stability, Catalytic Activity, and Enantioselectivity of Metal-Organic Frameworks for Batch and Flow Reactions. J. Am. Chem. Soc. 2017, 139, 13476-13482. (15) Slater, B.; Wang, Z.; Jiang, S.; Hill, M. R.; Ladewig, B. P. Missing Linker Defects in a Homochiral Metal-Organic Framework: Tuning the Chiral Separation Capacity. J. Am. Chem. Soc. 2017, 139, 18322-18327. (16) Ullah, S.; Yunus, U.; Bhatti, M. H.; Southon, P. D.; Iqbal, K.; Zaidi, S. Homochiral Metal Organic Frameworks and Their Usage for the Enantio-Purification of Racemic Drugs. ChemistrySelect. 2018, 3, 10434-10438. (17) Zhao, Y. W.; Wang, Y.; Zhang, X. M. Homochiral MOF as Circular Dichroism Sensor for Enantioselective Recognition on Nature and Chirality of Unmodified Amino Acids. ACS Appl. Mater. Interfaces. 2017, 9, 20991-20999. (18) Kuang, R.; Zheng, L.; Chi, Y.; Shi, J.; Chen, X.; Zhang, C. Highly efficient electrochemical recognition and quantification of amine enantiomers based on a guest-free homochiral MOF. RSC Adv. 2017, 7, 11701-11706.


18

Page 19 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(19) Guan, G. X.; Liu, X.; Yue, Q.; Gao, E. Q. Homochiral Metal-Organic Frameworks Embedding Helicity Based on a Semirigid Alanine Derivative. Cryst. Growth Des. 2017, 18, 364372. (20) Liang, L. L.; Gao, Y. Y.; Yue, Q.; Gao, E, Q. Photoluminescence, magnetic and photocatalytic properties of three overlapping layered homochiral coordination polymers based on semi-rigid alanine ligands. Inorg. Chem. Acta. 2017, 461, 102-110. (21) Zhuo, C.; Wen, Y.; Hu, S.; Sheng, T.; Fu, R.; Xue, Z.; Zhang, H.; Li, H.; Yuan, J.; Chen, X.; Wu. X. Homochiral Metal-Organic Frameworks with Tunable Nanoscale Channel Array and Their Enantioseparation Performance against Chiral Diols. Inorg. Chem. 2017, 56, 6275−6280. (22) Guan, G. X.; Guo, W. X.; Liu, X.; Yue, Q.; Gao, E. Q. Homochiral coordination polymers constructed from V-shaped oxybisbenzoyl-based amino acid derivatives: structures, magnetic and photoluminescence properties. Dalton Trans. 2018, 47, 13990-14000. (23) Koh, L. L.; Ranford, J. O.; Robinson, W. T.; Svensson, Jan. O.; Tan, A. L. C.; Wu, D. Model for the Reduced Schiff Base Intermediate between Amino Acids and Pyridoxal: Copper(II) Complexes of N-(2-Hydroxybenzyl)amino Acids with Nonpolar Side Chains and the Crystal Structures of [Cu(N-(2-hydroxybenzyl)-D,L-alanine)(phen)], H2O and [Cu(N-(2-hydroxybenzyl)D,L-alanine)(imidazole)]. Inorg. Chem. 1996, 35, 6466-6472. (24) Karmakar, A.; Oliver, C. L.; Roy, S.; Ohrstrom, L. The synthesis, structure, topology and catalytic application of a novel cubane-based copper(II) metal-organic framework derived from a flexible amido tripodal acid. Dalton trans. 2015, 44, 10156-10165.


19


Page 20 of 31

(25) Wang, X.; Zhang, K.; Lv, L.; Chen, R.; Wang, W.; Wu, B. Homochiral Coordination Polymers Based on Amino Acid-Functionalized Isophthalic Acid: Synthesis, Structure Determination, and Optical Properties. Cryst. Growth Des. 2018, 18, 1799-17808. (26) Wu, X.; Zhang, H. B.; Xu, Z. X.; Zhang, J. Asymmetric induction in homochiral MOFs: from interweaving double helices to single helices. Chem. Commun. 2015, 51, 16331-16333. (27) Chen, Z.; Liu, X.; Zhang, C.; Zhang, Z.; Liang, F. Structure, adsorption and magnetic properties of chiral metal-organic frameworks bearing linear trinuclear secondary building blocks. Dalton Trans. 2011, 40, 1911-1918. (28) Xu, Z. X.; Liu, L.; Zhang, J. Synthesis of Metal-Organic Zeolites with Homochirality and High Porosity for Enantioselective Separation. Inorg. Chem. 2016, 55, 6355-6357. (29) Grancha, T.; Ferrando-Soria, J.; Proserpio, D. M.; Armentano, D.; Pardo, E. Toward Engineering Chiral Rodlike Metal-Organic Frameworks with Rare Topologies. Inorg. Chem. 2018, 57, 12869-12875. (30) Mon, M.; Bruno, R.; Tiburcio, E.; Casteran, P. E.; Ferrando-Soria, J.; Armentano, D.; Pardo, E. Efficient Capture of Organic Dyes and Crystallographic Snapshots by a Highly Crystalline Amino-Acid-Derived Metal-Organic Framework. Chem. Eur. J. 2018, 24, 17712-17718. (31) Nicasio, A. I.; Montilla, F.; Alvarez, E.; Colodrero, R. P.; Galindo, A. Synthesis and structural characterization of homochiral 2D coordination polymers of zinc and copper with conformationally flexible ditopic imidazolium-based dicarboxylate ligands. Dalton Trans. 2017, 46, 471-482.


20

Page 21 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(32) Sahoo, S. C.; Kundu, T.; Banerjee, R. Helical water chain mediated proton conductivity in homochiral metal-organic frameworks with unprecedented zeolitic unh-topology. J. Am. Chem. Soc. 2011, 133, 17950-17958. (33) Wu, B.; Wang, S.; Wang, R.; Xu, J.; Yuan, D.; Hou, H. Chiral Metallocycles Templated Novel Chiral Water Frameworks. Cryst. Growth Des. 2013, 13,518-525. (34) Kuang, X.; Ma, Y.; Su, H.; Zhang, J.; Dong, Y. B.; Tang, B. High-Performance Liquid Chromatographic Enantioseparation of Racemic Drugs Based on Homochiral Metal-Organic Framework. Anal. Chem. 2014, 86, 1277-1281. (35) Huang, S. L.; Lin, Y. J.; Andy Hor, T. S.; Jin, G. X. CpRh-Based Heterometallic Metallarectangles: Size-Dependent Borromean Link Structures and Catalytic Acyl Transfer. J. Am. Chem. Soc. 2013, 135, 8125-8128. (36) Li, H.; Han, Y. F.; Lin, Y. J.; Guo, Z. W.; Jin, G. X. Stepwise Construction of Discrete Heterometallic Coordination Cages Based on Self-Sorting Strategy. J. Am. Chem. Soc. 2014, 136, 2982-2985. (37) Huang, S. L.; Lin, Y. J.; Li, Z. H.; Jin, G. X. Self-Assembly of Molecular Borromean Rings from Bimetallic Coordination Rectangles. Angew. Chem. Int. Ed. 2014, 53, 11218-11222. (38) Lu, Y.; Zhang, H. N.; Jin, G. X. Molecular Borromean Rings Based on Half-Sandwich Organometallic Rectangles. Acc. Chem. Res. 2018, 51, 2148-2158. (39) Jayaramulu, K.; Reddy, J. S. K.; Hazra, A.; Balasubraanian, S.; Maji, T. K. ThreeDimensional Metal-Organic Framework with Highly Polar Pore Surface: H2 and CO2 Storage Characteristis. Inorg. Chem. 2012, 51, 7103-7111.


21


Page 22 of 31

(40) Chen, B.; Lv, Z. P.; Leong, C. F.; Zhao, Y.; DʼAlessandro, D. M.; Zuo, J. L. Crystal Structures, Gas Adsorption, and Electrochemical Properties of Electroactive Coordination Polymers Based on the Tetrathiafulvalene-Tetrabenzoate Ligand. Cryst. Growth Des. 2015, 15, 1861-1870. (41) Zhang, W. Q.; Wang, R. D.; Wu, Z. B.; Kang, Y. F.; Fan, Y. P.; Liang, X. Q.; Liu, P.; Wang, Y. Y. Comparative Study on Temperature-Dependent CO2 Sorption Behaviors of Two Isostructural N-Oxide-Functionalized 3D Dynamic Microporous MOFs. Inorg. Chem. 2018, 57, 1455-1463. (42) Wang, C.; Li, L. J.; Bell, J. G.; Lv, X. X.; Tang, S. F.; Zhao, X. B.; Thomas, K. M. Hysteretic Gas and Vapor Sorption in Flexible Interpenetrated Lanthanide-Based Metal-Organic Frameworks with

Coordinated

Molecular

Gating

via

Reversible

Single-Crystal-to-Single-Crystal

Transformation for Enhanced Selectivity. Chem. Mater. 2015, 27, 1502-1516. (43) Lama, P.; Aggarwal, H.; Bezuidenhout, C. X.; Barbour, L. J.; Giant Hysteretic Sorption of CO2: In Situ Crystallographic Visualization of Guest Binding within a Breathing Framework at 298 K. Angew. Chem. Int. Ed. 2016, 55, 13271-13275. (44) Zhao, Y. P.; Li, Y.; Cui, C. Y.; Xiao, Y.; Li, R.; Wang, S. H.; Zheng, F. K.; Guo, G. C. Tetrazole-Viologen-based Flexible Microporous Metal-Organic Framework with High CO2 Selective Uptake. Inorg. Chem. 2016, 55, 7335-7340. (45) Foo, M. L.; Matsuda, R.; Hijikata, Y.; Krishna, R.; Takata, M.; Kitagawa, S. An Adsorbate Discriminator Gate Effect in a Flexible Porous Coordination Polymer for Selective Adsorption of CO2 over C2H2. J. Am. Chem. Soc. 2016, 138, 3022-3030.


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Page 23 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(46) Choi, H. S.; Suh, M. P. Highly Selective CO2 Capture in Flexible 3D Coordination Polymer Networks. Angew. Chem. Int. Ed. 2009, 48, 6865-6869. (47) Yue, Q.; Yan, L.; Zhang, J. Y.; Gao, E. Q. Novel Functionalized Metal-Organic Framework Based on Unique Hexagonal Prismatic Clusters. Inorg. Chem. 2010, 49, 8647-8649. (48) Sanda, S.; Parshamoni, S.; Konar, S. Third-Generation Breathing Metal-Organic Framework with Selective, Stepwise, Reversible, and Hysteretic Adsorption Properties. Inorg. Chem. 2013, 52, 12866-12868. (49) Gregg, S. J.; Sing, K. S. W. Adsorption, Surface Area and Porosity. Academic: London, 1982. (50) Park, J. H.; Lee, W. R.; Kim, Y.; Lee, H. J.; Ryu, D. W.; Phang, W. J.; Hong, C. S. Interpenetration Control, Sorption Behavior, and Framework Flexibility in Zn(II) Metal-Organic Frameworks. Cryst. Growth Des. 2014, 14, 699−704. (51) Tomar, K.; Rajak, R.; Sanda, S.; Konar, S. Synthesis and Characterization of PolyhedralBased Metal-Organic Framework Using a Flexible Bipyrazole Ligand: Topological Analysis and Sorption Property Studies. Cryst. Growth Des. 2015, 15, 2732-2741. (52) Zhou, Y.; Liu, B.; Sun, X. D.; Li, J. T.; Li, G. H.; Huo, Q. S.; Liu, Y. L. Self-assembly of Homochiral Porous Supramolecular Organic Frameworks with Significant CO2 Capture and CO2/N2 Selectivity. Cryst. Growth Des. 2017, 17, 6653-6659. (53) Yuan, J. Q.; Li, J. T.; Kan, L.; Zou, L. F.; Zhao, J.; Li, D. S.; Li, G. H.; Zhang, L. R.; Liu, Y. L. A Microporous Heterovalent Copper-Organic Framework Based on [Cu2I]n and Cu2(CO2)4


23


Page 24 of 31

Secondary Building Units: High Performance for CO2 Adsorption and Separation and Iodine Sorption and Release. Cryst. Growth Des. 2018, 18, 5449-5455. (54) Liu, B.; Yao, S.; Liu, X.; Li, X.; Krishna, R.; Li, G.; Huo, Q.; Liu, Y. Two Analogous Polyhedron-Based MOFs with High Density of Lewis Basic Sites and Open Metal Sites: Significant CO2 Capture and Gas Selectivity Performance. ACS Appl. Mater. Interfaces. 2017, 9, 32820-32828. (55) Tan, Y. X.; Wang, F.; Zhang, J. Design and synthesis of multifunctional metal-organic zeolites. Chem. Soc. Rev. 2018, 47, 2130-2144. (56) Wang, F.; Kusaka, S.; Hijikata, Y.; Hosono, N.; Kitagawa, S. Development of a Porous Coordination Polymer with a High Gas Capacity Using a Thiophene-Based Bent Tetracarboxylate Ligand. ACS Appl. Mater. Interfaces. 2017, 9, 33455-33460. (57) Ryu, D. W.; Lee, W. R.; Lim, S. L.; Phang, W. J.; Hong, C. S. Two Homochiral Bimetallic Metal-Organic Frameworks Composed of a Paramagnetic Metalloligand and Chiral Camphorates: Multifunctional Properties of Sorption, Magnetism, and Enantioselective Separation. Cryst. Growth Des. 2014, 14, 6472-6477. (58) Liu, J.; Wang, F.; Ding, Q. R.; Zhang, J. Synthesis of an Enantipure Tetrazole-Based Homochiral CuI,II-MOF for Enantioselective Separation. Inorg. Chem. 2016, 55, 12520-12522. (59) Peng, Y.; Gong, T.; Zhang, K.; Lin, X.; Liu, Y.; Jiang, J, Cui, Y. Engineering chiral porous metal-organic frameworks for enantioselective adsorption and separation. Nat. Commun. 2014, 5, 4406-4414.


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Scheme 1. The structure of pyridyl-dicarboxylate alanine derivative (H2PDBAla).

Figure 1. (a) Coordination environment of the Co(II) ion in 1 (Symmetry codes: A = x, y, 0.25-z; B = 1+x, 1+y, z; C = 1-x, y, -z). All hydrogen atoms are omitted for clarity. (b) The single-stranded right-handed {Co-PDBAla} helical chain running along the c-axis. The 3D framework of 1 viewed from the (c) [001], (d) [100] and (e) [110] directions, respectively.


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Figure 2. The two-fold interpenetrating framework of 1 viewed from the (a) [110], (b) [001] and (c) [100] directions, respectively.


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Figure 3. (a) Coordination environment of the Cu(II) ion in 3 (Symmetry codes: A = 1+x, 1-y, 0.25+z; B = x, 1+y, z; C = 1+x, y, z). All hydrogen atoms are omitted for clarity. (b) The singlestranded right-handed helical chain running along the c-axis. (c) The 3D {Cu-PDBAla} framework of 3 constructed by the PDBAla2- anions and Cu(II) ions viewed down the c-axis. (d) The overall 3D framework of 3 viewed down the c-axis in the presence of the bpea ligand. (e) The overall 3D framework of 3 viewed down the a-axis.


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Figure 4. CO2 sorption isotherms of 1' (a) and 3' (b): 195 K (I), 273 K (II), 298 K (III). Filled and open symbols represent adsorption and desorption curves, respectively.


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Table 1. The crystallographic and structure refinement parameters of compounds 1-3. Compound

1

2

3

Formula

C23H24N5O8Co

C23H25N5O8Cu

C25H25N5O6Cu

Molecular weight

557.4

563.06

555.03

Crystal system

tetragonal

tetragonal

tetragonal

Space group

P4322

P4322

P41

a (Å)

8.0457(2)

7.9358(4)

13.2595(7)

b (Å)

8.0457(2)

7.9358(4)

13.2595(7)

c (Å)

48.965(2)

49.349(4)

19.0000(14)

α (°)

90

90

90

β (°)

90

90

90

γ (°)

90

90

90

Z

4

4

4

V(Å3)

3169.67(17)

3107.8(3)

3340.5(4)

ρcalcd (g cm-3)

1.168

1.203

1.104

μ (Mo Kα) (mm-1)

0.586

0.749

0.692

F(000)

1152

1164

1148

Reflections

44135 / 3978

42005 / 3798

45688 / 7343

Rint

0.0739

0.0320

0.0642

Data / restraints /

3978 / 2 / 179

3798 / 2 / 179

7343 / 4 / 334

Goodness-of-fit on F2

1.035

1.157

0.913

R1/wR2[I>2σ(I)]

0.0340, 0.0721

0.0350, 0.0865

0.0449, 0.1120

R1/wR2[all data]

0.0422, 0.0741

0.0371, 0.0909

0.0623, 0.1183

Largest residues (e A-3)

0.275, -0.218

0.300, -0.711

0.357, -0.207

collected/unique

parameters


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BRIEFS Novel HMOFs exhibiting distinctive helixes and high CO2 adsorption capability have been constructed by combination of V-shaped pyridyl-dicarboxylate alanine derivative and varied auxiliary N-donor ligands.

SYNOPSIS Three novel HPMOFs embedded by fascinating helixes have been synthesized using V-shaped pyridyl-dicarboxylate alanine derivative and different auxiliary N-donor ligands. Their distinctive structures and high CO2 adsorption capability are discussed in detail.


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For Table of Contents Use Only

Homochiral Porous Metal-Organic Frameworks Constructed from a V-Shaped Alanine Derivative Based on Pyridyl-Dicarboxylate

Qi Yue*, Wei-Xiao Guo, Yuan-Yuan Wang, Xiao-Lu Hu and En-Qing Gao


31

Homochiral Porous Metal-Organic Frameworks Constructed from a V

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