Article pubs.acs.org/IC
A Porous Metal−Organic Framework [Zn2(bdc)(L‑lac)] as a Coating Material for Capillary Columns of Gas Chromatography Dan-Dan Zheng,†,§ Li Wang,*,†,§ Tao Yang,‡,§ Yan Zhang,† Qian Wang,† Mohamedally Kurmoo,⊥ and Ming-Hua Zeng*,‡ †
College of Chemistry & Chemical Engineering, Xinjiang Normal University, Urumqi 830054, P. R. China Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, P. R. China ⊥ Institut de Chimie de Strasbourg, CNRS-UMR 7177, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg, France ‡
S Supporting Information *
ABSTRACT: The wide diversity in the structure, pore size, high surface area, adsorption affinity, and selective penetration renders metal−organic frameworks (MOF) attractive as highly efficient adsorbents for chromatographic separation. We report the results of chromatographic separation of four families of biochemically important compounds, viz., linear alkyl hydrocarbons (aldehyde, acid, and ketone), aromatic hydrocarbons (aldehyde, acid, and alcohol), cyclic hydrocarbons (ketone, alcohol, and ester) and aromatic hydrocarbons (ether, ester, and ester with alcohol) with two phenyls, employing the porous MOF [Zn2(bdc)(L-lac)] (L-lac = L-lactate; bdc = 1,4-benzenedicarboxylate) as the retention material of the capillary column. Its good performance relies on the robustness and chemical and thermal stability of the framework, the permanent porosity, and, most importantly, the host−guest interaction sites. The results from this work will also help in understanding the intermolecular forces based on host−guest interaction between the MOF and analytes.
■
advantages:15 (a) organic ligands can be easily designed and modified using the power of organic synthesis; (b) because of the fixed coordination geometries of both organic ligands and metal ions, a certain combination of rigid organic and inorganic building units always produces a specific polarized framework. By taking advantage of their regularity, rigidity/flexibility, variety, and designability in both structure and properties, MOFs are being regarded as advanced porous materials in separation science.15 Several attempts have been made to use MOFs for the LC separation of large molecules such as drugs,16 dyes,17 pollutants,18 peptides,19 and proteins20 because the separation of LC is usually performed at room temperature and it is not necessary to evaporate the analytes. However, much less attention has been paid to the separation of large molecules using GC because the high thermal stability is the primary requirement of the selected MOFs. Furthermore, most MOFs are not robust enough to show permanent porosity either because of a lack of rigidity resulting in the collapse of the framework upon guest removal or because host−guest interaction sites are too few in the porous framework to be useful for selective adsorption and separation. Therefore, the exploration of MOFs with robust pores, high thermal stability, and host−guest interaction sites for potential application in GC separation remains challenging.
INTRODUCTION The attractive properties of metal−organic frameworks (MOF), such as permanent porosity, high surface area, uniform structured cavities, and the availability of in-pore functionality and outer-surface modification, are favorable for different applications.1 For example, we have reported the first highly stable MOF [M3(lac)2(pybz)2] (M = Zn, Co) with double walls and iodine capture.2 We have also produced porous 4-foldinterpenetrated chiral frameworks exhibiting vapochromism, gas sorption, and a poisoning effect.3 The first stage of the MOF research area has experienced major development on the synthesis and design of novel topologies with variable chemical functionalities of the pores and surfaces. Yet, the second stage is still under development and the application of MOFs in gas storage, separation, catalysis, sensing, imaging, and other areas and of these materials as gas (GC) and liquid chromatographic (LC) stationary phases for separation are still in their infancy.4−14 GC separation is one of the most promising applications of MOFs. Despite considerable successful attempts being made to synthesize robust, porous metal−organic materials, those capable of selective adsorption and separation in GC have met with only limited success. Table S1 gives details of the application of MOFs as a GC stationary phase for separation. Compared to the other stationary phases used in commercial columns, such as a liquid-silicon-based material used in GC, octadecylsilyl (C18) used in LC, etc., the application of MOFs as GC and LC stationary phases for separation has unique © XXXX American Chemical Society
Received: June 2, 2017
A
DOI: 10.1021/acs.inorgchem.7b01413 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
The untreated column was first washed with 1 M NaOH for 2 h, followed by ultrapure water for 1 h, 0.1 M HCl for 2 h, and again with ultrapure water until the washings were neutral. It was then dried naturally. We adopted the following method23 to load the columns with [Zn2(bdc)(L-lac)]: a 10 mL ethanol suspension of [Zn2(bdc)(L-lac)] (1 mg·mL−1) was filled into the capillary column under the pressure of a vacuum pump (one end of the capillary column was sealed, and the other end was connected to a vacuum system to gradually remove the solvent under vacuum), and then it was pushed through the column to leave a wet coating layer on the inner wall of the capillary column. After coating, the capillary column settled for 2 h for conditioning under nitrogen. An additional 4 h of further conditioning of the capillary column was needed using a temperature program including three steps: 35 °C for 30 min, ramp from 35 to 200 °C at a rate of 2 °C·min−1, and 200 °C for 120 min. Besides, all of the temperatures in this experiment are below 200 °C. Thus, the stationary phase particles stabilized onto the inner wall of the [Zn2(bdc)(L-lac)]-coated column can withstand high gas flows and does not damage expensive detectors during experiments.
Here we chose linear alkyl hydrocarbons (aldehyde, acid, and ketone), aromatic hydrocarbons (aldehyde, acid, and alcohol), cyclic hydrocarbons (ketone, alcohol, and ester), and aromatic hydrocarbons (ether, ester, and ester with alcohol) with two phenyls as the targets because they have significant impact on food, medicine, and flavor with their antimicrobial and antibacterial activity.21 In this work, we report the use of a porous MOF, [Zn2(bdc)(L-lac)], as a coating material in a capillary column for GC separation. Using MOF-coated capillary column can overcome the disadvantages of poor resolution from diffusion resistance on bulky MOF packing column. After removing the coordinated and uncoordinated solvent molecules, there are many specific polarized sites in the organic ligands with benzene rings and carboxyl and hydroxyl groups and unsaturated metal sites. The robust and permanent porosity, good thermal and chemical stabilities and host−guest interaction sites make MOF excellent GC stationary phases. This work can provide a strong case of the application of MOF for GC separation of larger molecular and complex compounds. It can also aid in the understanding of intermolecular forces and the structural basis of these forces.
■
■
RESULTS AND DISCUSSION Structure and Characterization of Coating Materials of a GC Capillary. Two important factors for the effective separation are (a) the structure of the stationary phase and (b) its morphology within the column. The as-synthesized [Zn2(bdc)(L-lac)(DMF)]·DMF having pores of roughly 5 Å diameter are interconnected in three directions, in which ZnII ions and L-lactate ligands form one-dimensional (1D) chiral chains running along the a axis, and these chains are further linked by benzenedicarboxylate to form a three-dimensional (3D) coordination polymer. Upon heat pretreatment of a MOF-coated capillary column, both the coordinated and uncoordinated DMF molecules were removed and the channel cross-linked to produce the mesoporous open framework [Zn2(bdc)(L-lac)]; the size of the channels running along the a direction is around 9.4 × 20.4 Å2 (Figure 1). There are several specific sites in [Zn2(bdc)(L-lac)], which include unsaturated Zn metal sites and deprotonated 1,4-benzenedicarboxylate and L-lactate.
EXPERIMENTAL SECTION
Materials and Methods. All chemicals, reagents, and adsorbates used were analytical grade/chromatographic pure and were used without further treatment. An untreated fused-silica capillary column with a polyimide outer coating (10 m long ×0.25 mm internal diameter) was purchased from Yongnian Ruifeng Chromatography Ltd. (Hebei, China). GC measurements were performed on an Agilent 6890N (USA) with a flame ionization detector, a split injection port, and a capillary control unit. Nitrogen (99.999%) was used as the carrier gas with a constant velocity of 32 cm·s−1. The injector temperature was maintained at 250 °C, and the detector temperature was held at 250 °C. The instrument control and data acquisition were carried out by ChemStation software. The powder X-ray diffraction (PXRD) patterns were measured at 298 K on a Bruker D8 ADVANCE X-ray diffractometer (Germany) using Cu Kα radiation in the 2θ range from 5° to 70°. The Fourier transform infrared (FT-IR) spectra were recorded from KBr pellets in the range of 4000−600 cm−1 on a FT-IR TENSOR 27 (Germany) at room temperature. A total of 5 mg of the sample was mixed thoroughly with 500 mg of dried KBr. The thermogravimetric (TG) experiment was carried out on a simultaneous STA 409 PC Luxx thermal analyzer instrument (Germany), at a heating rate of 10 °C·min−1 in flowing N2 from 30 to 800 °C. Scanning electron microscopy (SEM) images were recorded on a Hitachi SU8010 scanning electron microscope (Japan). The elemental analysis (EI) experiment was performed on a Vario EL III elemental analyzer (Germany). Synthesis of the MOF. [Zn2(bdc)(L-lac)(DMF)]·DMF (DMF = dimethylformamide) was synthesized according to the literature.22 A DMF (10 mL) solution containing Zn(NO3)2·6H2O (300 mg, 1.0 mmol), L-lactic acid [(S)-2-hydroxypropionic acid] (45 mg, 0.5 mmol), and 1,4-benzenedicarboxylic acid (83 mg, 0.5 mmol) was placed in a Teflon-lined stainless steel autoclave and heated at 120 °C for 2 days. Following slow cooling of the autoclave to room temperature, the colorless rods were collected, washed with DMF, and dried. The yield of [Zn2(bdc)(L-lac)(DMF)]·DMF based on Zn is 89%. Elem anal. Calcd for [Zn2(bdc)(L-lac)(DMF)]·(DMF): C, 38.56; H, 4.17; N, 5.29. Found: C, 38.86; H, 4.43; N, 5.94. The desolvated [Zn2(bdc)(L-lac)] was obtained by heating [Zn2(bdc)(L-lac)(DMF)]· DMF at 220 °C for 2 h. Calcd: C, 34.49; H, 2.09; N, 0.00. Found: C, 33.97; H, 2.11; N, 0.07. Capillary Pretreatment and Preparation of a [Zn2(bdc)(Llac)]-Coated Capillary Column. A pretreatment of the commercially available untreated fused-silica capillary column (10 m length × 0.25 mm internal diameter) was necessary before loading with the MOF.
Figure 1. (a) View of the structure of as-synthesized [Zn2(bdc)(Llac)(DMF)]·DMF along the a axis with coordinated and solvent DMF molecules. (b) View along the a axis of the structure of [Zn2(bdc)(Llac)] with the coordinated and uncoordinated solvent DMF molecules removed, leaving a 1D prismatic channel of around 9.4 × 20.4 Å2. B
DOI: 10.1021/acs.inorgchem.7b01413 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
(DMF)]·DMF, a [Zn2(bdc)(L-lac)]-coated capillary column, and cross-sectioned SEM images of the coated columns. The fabricated column had an approximate 1−2-μm-thick MOF coating on the inner wall. GC Separation. Adsorptive separations refer to the process by which a mixture is separated based on differences in the adsorption/desorption behavior of distinct components and have a wide range of industrial applications. To evaluate the separation performance of the [Zn2(bdc)(L-lac)]-coated capillary column, four groups of compounds having different functional groups [R−OH, H−C(R)O, C(RR′)O, HO− C(R)O, R−O−C(R′)O, and R−O−R′] substituted for linear alkyl hydrocarbons, aromatic hydrocarbons, cyclic hydrocarbons, and aromatic hydrocarbons with two phenyls were selected. Polarity is an important factor affecting the selectivity for the separation of the compounds with different functional groups. To investigate its effect, McReynolds constants were measured to evaluate the polarity of the [Zn2(bdc)(L-lac)] stationary phases24 (see the Supporting Information). The McReynolds constants show weak polarity for [Zn2(bdc)(L-lac)], which is compared to that of dioctyl phthalate24 (Table S2). The whole separation design of four series of compounds is illustrated in Scheme 1. First, three compounds of the linear alkyl hydrocarbons decanal [decyl aldehyde] (A1), decanoic acid (A2), and methyl nonyl ketone [2-undecan-2-one] (A3) were selected as test solutes. Following injection of a mixture of the three compounds, A1, A3, and A2 were sequentially eluted (Figure 4a). These compounds contain a common straightchain paraffin backbone but with different functional groups H−C(R)O, HO−C(R′)O, and C(RR′)O. There are three interactions between A2 and the MOF, which induce the maximum retention of A2: dipole−dipole interaction25 between polarized C−O/CO of the MOF and the HO− C(R)O group of A2; interaction of unsaturated Zn2+ sites of the MOF with the HO−C(R)O groups of A2; weak hydrogen-bonding interaction26 between the MOF and HO− C(R)O groups of A2. For A3 and A1, there is dipole−dipole interaction between polarized C−O/CO of the MOF and C(RR′)O and H−C(R)O groups of adsorbates, and the dipole−dipole interaction between the adsorbate and adsorbent is larger in C(RR′)O than in H−C(R)O, so A3 is eluted later than A1. The comparison of the FT-IR spectra of the MOF, organic adsorbate, and their organic−MOF composite supports the above statements concerning the interaction between the adsorbate and MOF (Figure S3). For example, the CO stretching vibration of decanal at 1723 cm−1 is shifted to 1729 cm−1 when it is on the MOF. The order of magnitude is similar to that in the systematic study by Umadevi et al. demonstrating the variation from 1706 to 1719 cm−1 of the CO stretching mode of propionic acid in a different mole fraction with 2propanol. They associated this dependence to hydrogen bonding.27 The following assignments were also made: 2900 cm−1 (stretching CH3) and 1379 and 1460 cm−1 (CH2 deformation).28 For comparison to the linear alkyl hydrocarbons, we chose three compounds with the same aromatic phenyl and ene (C C) structures with different functional groups of H−C(R)O, HO−C(R)O, and R−OH: trans-cinnamaldehyde [(E)-3phenylprop-2-en-1-al] (B1), trans-cinnamic acid [(E)-3-phenylprop-2-enoic acid] (B2), and cinnamic alcohol [(E)-3-phenylprop-2-en-1-ol] (B3) as test solutes. The elution times were on
The similar PXRD patterns of the solvated and desolvated forms confirm the crystallinity and thermal stability (Figure S1) in agreement with the TG measurements (Figure S2). In the assynthesized [Zn2(bdc)(L-lac)(DMF)]·DMF, the pores are occupied by coordinated and guest DMF molecules that can readily be removed at a temperature of 220 °C. A TG analysis on the crystalline product of this compound indicates an approximately 28.0% loss of weight between 25 and 220 °C, which is due to the total weight of the coordinated and uncoordinated DMF molecules (calcd 27.6%). There is no significant shift or broadening of the peaks of the PXRD pattern of the desolvated form compared to those of the as-synthesized compound. The column was thermally stable up to 350 °C, which is suitable for GC (normally the work temperature of the oven for GC is below or at 200 °C). The corresponding solvent-accessible volume of the microporous MOF [Zn2(bdc)(L-lac)] was estimated to be as high as 41%, assuming a guest-free structure. The permanent porosity and Langmuir surface area was estimated to be 190 m2·g−1, which is similar to that of typical microporous zeolites.22 The structure of the MOF has permanent porosity and good thermal and chemical stabilities. All of these features suggest that it might be a potential candidate for the stationary phase. Figure 2 shows the flowchart of the whole GC. Figure 3 shows a photograph of the crystals of [Zn2(bdc)(L-lac)-
Figure 2. Flowchart of GC separation.
Figure 3. (a) Photograph of crystals of [Zn2(bdc)(L-lac)(DMF)]· DMF, (b) a [Zn2(bdc)(L-lac)]-coated capillary column, (c) SEM images of the cross section of the capillary column, and (d) morphology of [Zn2(bdc)(L-lac)] deposited on the inner wall of the capillary column.
C
DOI: 10.1021/acs.inorgchem.7b01413 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry Scheme 1. Illustration for the Separation Design of Four Series of Compounds
Figure 4. Representative GC chromatograms on the MOF-coated open tubular column for separation of the following: (a) A1, decanal [decyl aldehyde]; A2, decanoic acid; A3, methyl nonyl ketone [2-undecan-2-one]; (b) B1, trans-cinnamaldehyde [(E)-3-phenylprop-2-en-1-al]; B2, transcinnamic acid [(E)-3-phenylprop-2-enoic acid]; B3, cinnamic alcohol [(E)-3-phenylprop-2-en-1-ol]; (c) C1, menthone [2-isopropyl-5methylcyclohexanone]; C2, thymol [2-isopropyl-5-methylphenol]; C3, menthyl acetate [2-isopropyl-5-methylcyclohexyl acetate]; (d) D1, diphenyl ether [1-phenoxybenzene]; D2, benzyl benzoate; D3, benzyl salicylate [benzyl 2-hydroxybenzoate]. All injection volumes are 0.1 μL, and the flow rate is 1 mL·min−1. The details of the compounds are shown in Table 1.
and MOF];29 (c) weak hydrogen bonding [H donors of R−OH and B2 and C−O/CO of MOF], and (d) unsaturated Zn2+ sites [MOF and HO−C(R)O of B2]. In the case of B3, there are three kinds of interactions between B3 and the MOF: (a) dipole−dipole, (b) C−H···π, and hydrogen bonding. As for B1,
the order B1 < B3 < B2 (Figure 4b). With four interactions between B2 and the MOF, it has accordingly the longest retention time. The interactions comprise (a) dipole−dipole [C−O/CO of the MOF with C−O/CO of B2], (b) C− H···π attractive [H+ and the π electron from both adsorbates D
DOI: 10.1021/acs.inorgchem.7b01413 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry Table 1. Interactions and Chromatographic Elution Sequence
there are only two interactions: (a) dipole−dipole; (b) C− H···π between B1 and the MOF. For the third series, we chose three compounds from aromatic hydrocarbons to cycloalkanes as test solutes: menthone [2-isopropyl-5-methylcyclohexanone] (C1), thymol [2-isopropyl-5-methylphenol] (C2), and menthyl acetate [2isopropyl-5-methylcyclohexyl acetate] (C3). The mixtures were eluted in the order of C1, C3, and C2 (Figure 4c). Among them, C1 and C3 have naphthenic hydrocarbon structures, while C2 has a phenyl ring. C1 has the polarized ketone structure RC(R′)O, while C3 has the ester RO−C(R′)O. Here C2 eluted last because of dipole−dipole, C−H···π attractive, and weak hydrogen-bonding interactions between C2 and the MOF, while C3 eluted later than C1 because the dipole−dipole interaction between the adsorbate and adsorbent is RO-C(R′)O > C(RR′)O. The last series chosen have aromatic hydrocarbons (ether, ester, and ester with alcohol) with two phenyls as test solutes: diphenyl ether [1-phenoxybenzene] (D1), benzyl benzoate (D2), and benzyl salicylate [benzyl 2-hydroxybenzoate] (D3). The order of elution time was D1 < D2 < D3 (Figure 4d). There are two possible interactions between these three compounds and the MOF [Zn2(bdc)(L-lac)]: (a) dipole− dipole [C−O/CO of the MOF and C−O/CO of the adsorbates] and (b) C−H···π [H+−π from both the adsorbates and MOF]. In addition to the two interactions, D3 also makes a hydrogen bond between its R−OH and C−O/CO of the MOF. D2 is eluted slower than D1 because the dipole−dipole interaction is larger in RO−C(R′)O than in R−O−R′. Figure 5 gives the four main interactions between the adsorbate and adsorbent in this work. The point of this work not only affords an example of using a porous MOF, [Zn2(bdc)(L-lac)], as the coated material in the
Figure 5. Four main interactions between adsorbate and adsorbent: (a) unsaturated Zn2+ sites; (b) dipole−dipole; (c) C−H···π attraction and (d) H- bond.
capillary column for GC separation but also can help in understanding the intermolecular forces based on host−guest interaction between the MOF and analytes in gas flow conditions. From the four groups of analysts, we can draw the following conclusions: (i) more host−guest interacting sites, more host−guest interaction types, stronger interaction between the host and guest. For example, during separation of the B group, there are four interactions between B2 and the MOF, which induce the last elution of B2, while there are three kinds of interaction between B3 and the MOF, which induce E
DOI: 10.1021/acs.inorgchem.7b01413 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
importantly, the separation targets can be expanded from aldehyde, alcohol, ester, and amine to acids, which are favorable for the unsaturated Zn2+ sites. Also, we tried other porous MOFs like MOF5, but we did not get ideal separation results. Thus, a polarization gradient for the rich polarized groups, unsaturated metal sites, weak van der Waals interaction, and hydrogen-bonding interaction are important for the chromatographic separation.
the second elution of B3, and there are two kinds of interactions between B1 and the MOF, which induce the first elution of B1. (ii) Unsaturated metal-coordinated sites delay the retention time more than other interactions (dipole− dipole, C−H···π, and hydrogen bonding). For example, during separation of the molecules within the A and B groups, unsaturated Zn2+ sites of the MOF interact with HO−C(R) O groups > polarized C−O/CO groups, which induce the last elution of A2 and B2. (iii) The C−H···π attractive interaction between aromatic hydrocarbons and the MOF is stronger than those of cycloalkanes and MOFs. For example, C2 eluted last mostly because of C−H···π attractive interaction between C2 and the MOF. Separation Ability and Reusability of a [Zn2(bdc)(Llac)]-Coated Column. To judge the separation ability of the [Zn2(bdc)(L-lac)]-coated column for organic compounds, the results of the separation are expressed as retention factors (k), separation factors (α), and resolutions (RS) (Table S3). As shown in Table S3, all chromatographic resolution values (RS) are higher than 1.5 (the request for separation of two compounds), even more, some of them higher than 6. This result suggests that the [Zn2(bdc)(L-lac)]-coated material is a good candidate of the stationary phase for GC separation. All of the experiment in this work has been reproduced using more than one column and more than 300 turns on every column. The [Zn2(bdc)(L-lac)]-coated columns were physically and chemically robust and were shown to be reusable (>300 injections; Figure S4). Figure S4 shows of the 50th, 100th, 150th, 200th, and 250th turns of the separation results of diphenyl ether, benzyl benzoate, and benzyl salicylate, using one [Zn2(bdc)(L-lac)]-coated column. These results confirm that the [Zn2(bdc)(L-lac)]-coated column is stable, and separation is reproducible. Furthermore, subjecting the column to different split ratios has no significant influence on the retention time and selectivity (Figure S5). According to the literature,7 the recognition ability of the MOF-coated column is often compared to the widely used commercial column,DB-1 [100% poly(dimethylsiloxane)]. For separation of the multiaromatic hydrocarbons (ether, ester, and ester with alcohol, that is, the fourth group of analytes D1, D2, and D3), the [Zn2(bdc)(L-lac)]-coated column showed more effective recognition ability than the commercial DB-1 column (Figure S6). The chromatographic activity of [Zn2(bdc)(L-lac)] may be compared to those of other MOFs such as [Cd(D-cam)(tmdpy)]30 and [Mn3(HCOO)2(D-cam)2(DMF)2].31 Although they all are MOFs being used as coating materials in capillary columns for GC separation, different structures, different physical and chemical properties, different weak interactions, and different host−guest sites, together with the robust and permanent porosity and good thermal and chemical stabilities, all lead to their different separation properties. For example, for the coating material [Mn3(HCOO)2(D-cam)2(DMF)2], there are more specific sites from the three mixed organic ligands HCOO−, D-cam, and DMF, thus affording a polarization gradient for the rich polarized CO, C−O, and N−CO groups. In this case, it is more suitable for the separation of targets including aldehyde, alcohol, ester, and amine. In contrast, [Zn2(bdc)(L-lac)] used in the present work provides not only the polarization gradient of the CO, C−O, and N− CO groups for separation but also the unsaturated Zn2+ sites coming from the departure of the coordinated and uncoordinated DMF molecules for more efficient separation. More
■
CONCLUSION In summary, we have successfully developed a stationary phase of a Zn-based MOF with large pores exhibiting specific recognition and selectivity for the separation of several families of biochemically important compounds with different functional groups [R−OH, H−C(R)O, C(RR′)O, HO− (R)CO, RO−(R′)CO, and R−O−R′]. This porous MOF material proves to be very promising as a stationary phase for GC separation application.
■
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b01413. Characterization (PXRD and TG) of the MOF, the FTIR of the analyte and MOF, chromatographic parameters of GC separation, GC chromatograms, and the McReynolds constants for the [Zn2(bdc)(L-lac)]-coated column (PDF)
■
AUTHOR INFORMATION
Corresponding Authors
*E-mail:
[email protected] (L.W.). *E-mail:
[email protected] (M.-H.Z.). ORCID
Li Wang: 0000-0002-7425-6872 Tao Yang: 0000-0003-1864-8545 Mohamedally Kurmoo: 0000-0002-5205-8410 Author Contributions §
These authors contributed equally to this work.
Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS This work is supported by the NSFC (Grants 21371147, 21365021, 21371037, and 51762039) and XJSF (Grant QN2016YX0126). M.K. is funded by the CNRS (France).
■
REFERENCES
(1) Kreno, L. E.; Leong, K.; Farha, O. K.; Allendorf, M.; Van Duyne, R. P.; Hupp, J. T. Metal-Organic Framework Materials as Chemical Sensors. Chem. Rev. 2012, 112, 1105−1125. (2) Zeng, M. H.; Yin, Z.; Tan, Y. X.; Zhang, W. X.; He, Y. P.; Kurmoo, M. Nanoporous Cobalt(II) MOF Exhibiting Four Magnetic Ground States and Changes in Gas Sorption upon Post-Synthetic Modification. J. Am. Chem. Soc. 2014, 136, 4680−4688. (3) Zeng, M. H.; Tan, Y. X.; He, Y. P.; Yin, Z.; Chen, Q.; Kurmoo, M. A porous 4-fold-interpenetrated chiral framework exhibiting vapochromism, single-crystal-to-single-crystal solvent exchange, gas sorption, and a poisoning effect. Inorg. Chem. 2013, 52, 2353−2360. (4) Lin, J. M.; He, C. T.; Liao, P. Q.; Lin, R. B.; Zhang, J. P. Structural, energetic, and dynamic insights into the abnormal xylene
F
DOI: 10.1021/acs.inorgchem.7b01413 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry separation behavior of hierarchical porous crystal. Sci. Rep. 2015, 5, 11537. (5) Gu, Z. Y.; Yang, C. X.; Chang, N. A.; Yan, X. P. Metal−organic frameworks for analytical chemistry: from sample collection to chromatographic separation. Acc. Chem. Res. 2012, 45, 734−745. (6) Chen, B. L.; Liang, C. D.; Yang, J.; Contreras, D. S.; Clancy, Y. L.; Lobkovsky, E. B.; Yaghi, O. M.; Dai, S. A Microporous Metal-Organic Framework for Gas-Chromatographic Separation of Alkanes. Angew. Chem. 2006, 118, 1418−1421. (7) Finsy, V.; Verelst, H.; Alaerts, L.; De Vos, D.; Jacobs, P. A.; Baron, G. V.; Denayer, J. F. Pore-Filling-Dependent Selectivity Effects in the Vapor-Phase Separation of Xylene Isomers on the MetalOrganic Framework MIL-47. J. Am. Chem. Soc. 2008, 130, 7110−7118. (8) Alaerts, L.; Maes, M.; Giebeler, L.; Jacobs, P. A.; Martens, J. A.; Denayer, J. F.; Kirschhock, C. E. A.; De Vos, D. E. Selective adsorption and separation of ortho-substituted alkylaromatics with the microporous aluminum terephthalate MIL-53. J. Am. Chem. Soc. 2008, 130, 14170−14178. (9) Gu, Z. Y.; Yan, X. P. Metal-Organic Framework MIL-101 for High-Resolution Gas-Chromatographic Separation of Xylene Isomers and Ethylbenzene. Angew. Chem., Int. Ed. 2010, 49, 1477−1480. (10) Chang, N.; Gu, Z. Y.; Yan, X. P. Zeolitic imidazolate framework8 nanocrystal coated capillary for molecular sieving of branched alkanes from linear alkanes along with high-resolution chromatographic separation of linear alkanes. J. Am. Chem. Soc. 2010, 132, 13645−13647. (11) Chang, N.; Gu, Z. Y.; Wang, H. F.; Yan, X. P. Metal−organicframework-based tandem molecular sieves as a dual platform for selective microextraction and high-resolution gas chromatographic separation of n-alkanes in complex matrixes. Anal. Chem. 2011, 83, 7094−7101. (12) Chang, N.; Gu, Z. Y.; Wang, H. F.; Yan, X. P. Metal-organicframework-based tandem molecular sieves as a dual platform for selective microextraction and high-resolution gas chromatographic separation of n-alkanes in complex matrixes. Anal. Chem. 2011, 83, 7094−7101. (13) Xie, S. M.; Yuan, L. M. Recent progress of chiral stationary phases for separation of enantiomers in gas chromatography. J. Sep. Sci. 2017, 40, 124−137. (14) He, C. T.; Jiang, L.; Ye, Z. M.; Krishna, R.; Zhong, Z. S.; Liao, P. Q.; Xu, J.; Ouyang, G.; Zhang, J.-P.; Chen, X. M. Exceptional Hydrophobicity of a Large-Pore Metal-Organic Zeolite. J. Am. Chem. Soc. 2015, 137, 7217−7223. (15) Li, J. R.; Sculley, J.; Zhou, H. C. Metal-Organic Frameworks for Separations. Chem. Rev. 2012, 112, 869−932. (16) Horcajada, P.; Serre, C.; Vallet-Regí, M.; Sebban, M.; Taulelle, F.; Férey, G. Metal-Organic Frameworks as Efficient Materials for Drug Delivery. Angew. Chem., Int. Ed. 2006, 45, 5974−5978. (17) He, Y. C.; Yang, J.; Kan, W. Q.; Zhang, H. M.; Liu, Y. Y.; Ma, J. F. A new microporous anionic metal-organic framework as a platform for highly selective adsorption and separation of organic dyes. J. Mater. Chem. A 2015, 3, 1675−1681. (18) Cychosz, K. A.; Wong-Foy, A. G.; Matzger, A. J. Liquid phase adsorption by microporous coordination polymers: removal of organosulfur compounds. J. Am. Chem. Soc. 2008, 130, 6938−6939. (19) Huang, H. Y.; Lin, C. L.; Wu, C. Y.; Cheng, Y. J.; Lin, C. H. Metal organic framework-organic polymer monolith stationary phases for capillary electrochromatography and nano-liquid chromatography. Anal. Chim. Acta 2013, 779, 96−103. (20) Gu, Z. Y.; Chen, Y. J.; Jiang, J. Q.; Yan, X. P. Metal-organic frameworks for efficient enrichment of peptides with simultaneous exclusion of proteins from complex biological samples. Chem. Commun. 2011, 47, 4787−4789. (21) Michiels, J.; Missotten, J.; Dierick, N.; Fremaut, D.; Maene, P.; De Smet, S. In vitro degradation and in vivo passage kinetics of carvacrol, thymol, eugenol and trans-cinnamaldehyde along the gastrointestinal tract of piglets. J. Sci. Food Agric. 2008, 88, 2371−2381. (22) Dybtsev, D. N.; Nuzhdin, A. L.; Chun, H.; Bryliakov, K. P.; Talsi, E. P.; Fedin, V. P.; Kim, K. A homochiral metal-organic material
with permanent porosity, enantioselective sorption properties, and catalytic activity. Angew. Chem., Int. Ed. 2006, 45, 916−920. (23) Nikelly, J. G. Preparation of porous layer open tubular columns by the dynamic method. Anal. Chem. 1972, 44, 623−625. (24) McReynolds, W. O. Characterization of some liquid phases. J. Chromatogr. Sci. 1970, 8, 685−691. (25) Li, W. K.; Zhou, G. D.; Mak, T. C. Advanced Structural Inorganic Chemistry; Oxford University Press, 2008. (26) Jeffrey, G. A. Hydrogen-bonding: an update. Crystallogr. Rev. 2003, 9, 135−176. (27) Umadevi, M.; Thomas, A. E. Fourier transformed infrared spectral investigations of molecular interactions in propionic acid-2propanol binary system. Spectrochim. Acta, Part A 2010, 75, 1181− 1190. (28) Francis, S. A. Intensities of some characteristic infrared bands of ketones and esters. J. Chem. Phys. 1951, 19, 942−948. (29) Tsuzuki, S. CH/π interactions. Annu. Rep. Prog. Chem., Sect. C: Phys. Chem. 2012, 108, 69−95. (30) Zhang, Y.; Wang, L.; Zeng, M. H.; Kurmoo, M. Fabrication of a Capillary Column Coated with the Four-Fold-Interpenetrated MOF Cd(D-Cam)(tmdpy) for Gas Chromatographic Separation. Inorg. Chem. Commun. 2017, 83, 123−126. (31) Zheng, D. D.; Zhang, Y.; Wang, L.; Kurmoo, M.; Zeng, M. H. A rod-spacer mixed ligands MOF [Mn3(HCOO)2(Dcam)2(DMF)2]n as coating material for gas chromatography capillary colum. Inorg. Chem. Commun. 2017, 82, 34−38.
G
DOI: 10.1021/acs.inorgchem.7b01413 Inorg. Chem. XXXX, XXX, XXX−XXX
