- Email: [email protected]
Synthesis, structure and gas adsorption properties of a microporous metal–organic framework assembled from a semi-rigid tripodal carboxylic acid ligand
Accepted Manuscript Synthesis, structure and gas adsorption properties of a microporous metal–organic framework assembled from a semirigid tripodal carboxylic acid ligand
Baohui Liu, Xin Li, Shengjun Dong, Mingkai Li, Yujiu Wang PII: DOI: Reference:
S1387-7003(17)30253-8 doi: 10.1016/j.inoche.2017.04.011 INOCHE 6616
To appear in:
Inorganic Chemistry Communications
Received date: Revised date: Accepted date:
31 March 2017 13 April 2017 15 April 2017
Please cite this article as: Baohui Liu, Xin Li, Shengjun Dong, Mingkai Li, Yujiu Wang , Synthesis, structure and gas adsorption properties of a microporous metal–organic framework assembled from a semi-rigid tripodal carboxylic acid ligand. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Inoche(2017), doi: 10.1016/j.inoche.2017.04.011
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Synthesis, structure and gas adsorption properties of a microporous metal–organic framework assembled from a semi-rigid tripodal carboxylic acid li-
PT
gand
Department of Cardiac Surgery, Binzhou Medical University Hospital, Binzhou Medical Univer-
SC
1
RI
Baohui Liu1§, Xin Li2§, Shengjun Dong1, Mingkai Li3, Yujiu Wang1*
sity, Binzhou, Shandong, China
Department of Pharmacology, School of Pharmacy, the Fourth Military Medical University, Xi’an,
MA
3
Department of gynecology, Binzhou People`s Hospital, Binzhou, Shandong, China
NU
2
AC
CE
PT E
D
China
§
These authors contributed equally to this paper.
* Corresponding author. E-mail address: [email protected].
Inorg. Chem. Commun
1
ACCEPTED MANUSCRIPT
Abstract. The design, synthesis, and structural characterization of a new cubic three-dimensional microporous metal–organic
framework
featuring
a
semi-rigid
tripodal
carboxylic
acid
ligand,
4,4′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda), is reported. Single-crystal X-ray diffraction analysis indicates that compound 1 possesses a novel (3,4,4)-connected network with the point symbol of {83}4{84.102}2{86}. In the framework of 1, there co-exist two types of 1D channels with different pore size (15 Å
PT
and 4.5 Å). The pore characteristics and gas sorption properties of this compound were investigated both at cryogenic temperatures and room temperature by experimentally measuring N2 and CO2 sorption isotherms. These
RI
studies show that compound 1 is highly porous with a pore volume of 0.98 cm3/g and BET surface of 1926 cm3/g.
Cu(II)-based MOF; (3,4,4)-connected topology; hierarchical porosity; gas sorption
MA
NU
Keywords:
SC
In addition, the activated 1 also shows excellent CO2 storage capacity around room temperature.
As an emerging class of hybrid crystalline materials, metal–organic frameworks (MOFs) that are self-assembled
D
from metal ions or clusters with organic ligands have attracted considerable attention owing to their great potential
PT E
in a wide variety of applications such as gas storage/separation, sensor, catalysis and fluorescent material [1-13]. Among the diverse applications of MOFs, gas storage and separation will probably play a key role in future due to
CE
the rising energy- and environment-related issues faced by our society [14]. The extremely high surface areas, adjustable pore sizes, as well as intriguing functionalities make them more competitive over other traditional ad-
AC
sorbent materials, such as zeolites, activated carbons, or diatomite. The ability to rationally design and modify the crystal structures of MOF materials is the key to achieve high adsorption capacity and selectivity to meet specific storage/separation needs and to increase the potential for commercial applications [15]. One particularly useful and extensively studied strategy in forming porous structures with controlled topology, large pore volume, and framework integrity is to make use of secondary building units (SBU) with different shapes, sizes, and binding modes [16]. For example, a family of highly porous MOFs have been constructed using Zn4O(COO)6 as the SBU
2
ACCEPTED MANUSCRIPT [17]. The octahedral geometry and six-fold connectivity of this SBU leads to a cubic structure. The paddle-wheel unit Cu2(COO)4(L2) is another type of SBU with a slightly different topology and connectivity from Zn4O(COO)6, typically resulting in a tetragonal (distorted cubic) structure. By simply varying the length of organic linkers, isostructural compounds with a range of pore space can be obtained with the same SBU. However, the increasing the
PT
length of ligand usually accompanies with framework interpenetration, which is not beneficial for obtaining high-
RI
ly porous MOFs. For instance, the combination of Cu2(COO)4 unit with H3BTC ligand affords the famous
SC
HKUST-1 [18]; when replacing the H3BTC ligand with the H3BTB ligand, Cu3(BTB)2 (MOF-14) with similar
NU
framework connection but 2-fold interpenetrated network was obtained [19].
In this study, we present the synthesis, structure and gas sorption properties of a novel non-interpenetrating cpbda
with a high pore volume and BET surface that constructed
MA
Cu(II)-based MOF
from the binuclear Cu2(COO)4 unit and a semi-rigid tripodal carboxylic acid. In the framework of this compound,
D
there exist two types of 1D channels along the c axis, one with a pore diameter of 15 Å and the other features a
PT E
pore diameter of 4.5 Å. We explored the porosity and gas sorption capacity of compound 1. The N2 adsorption at
CE
77 K shows compound 1 is microporous with BET surface of
AC
Single-crystal X-ray structural analysis shows that compound 1 possesses a 3D neutral framework and crystallizes in the tetragonal space group P4/nnc. The asymmetric unit of 1 contains three independent Cu atoms (Cu2 and Cu3 with an occupancy of 0.25), two coordinated water molecules and one fully deprotonated cpbda3- ligand (Fig S1). All the Cu2+ ions in 1 are five-coordinated by four carboxylic O atoms from four different cpbda3ligands and one O atom from a water molecule, resulting in a tetragonal pyramidal geometry. The Cu-O bond distances are in the range of 1.995(5) to 2.196(8) Å. The distance between Cu1 and Cu1A, Cu2 and Cu3 is 2.612(2) and 2.633(2) Å, respectively. There are two different binuclear Cu2+ units in the framework of 1, one is formed by 3
ACCEPTED MANUSCRIPT the Cu1 and Cu1A atoms and the other consists of the Cu2 and Cu3 atoms (Fig S2). The two benzene ring arms of the cpbda3- ligand bend significantly, resulting in a T-shape molecular geometry. The dihedral angles between the o
o
central benzene ring and the two side benzene rings are 77.9(7) (left) and 93.6(3) (right) (Fig S3). The most no-
ticeable structural feature of 1 is the co-existing of interlacing circular channels and quadrate channels with two
PT
different sizes (15 Å and 4.5 Å, Fig 1a). The larger one is formed by four paddle-wheel units and eight long arms
RI
from eight different cpbda3- ligands; the smaller one is shaped by two paddle-wheel units, two short arms and two
SC
long arms of the cpbda3- ligands. Moreover, we can find unique 1D helical chains running along c axis in the structure of 1. The helix is constructed by one short arm and one long arm of the adjacent cpbda3- ligands that connected by
NU
the paddle-wheel units, displaying left-handed and right-handed helical chains, with the pitch of the helix being 10.86(2)
MA
Å (Fig S4). Each large channel is surrounded by the eight small channels and each small channel is nearby two large channels. So the whole framework of 1 could be also regarded as a packing of small quadrate channels and
D
large circular channels in the ratio of 2:1 along the c axis. The total void volume available to guest molecules in 1
PT E
was estimated by PLATON/SOLV (probe radius of 1.2 Å) calculations to be 71.5% of the total crystal volume (Fig 1b), and low crystallography density of 0.64 g/cm3, corresponding to a theoretical pore volume of 1.12 cm3/g
CE
[19]. The free spaces are occupied by the structurally disordered solvent molecules. Topology analysis is applied
AC
in order to better understand the structure of compound 1. If the binuclear Cu units are viewed as 4-connected nodes and cpbda3- ligand could be judged as a 3-connected node, so the resulting structure of compound 1 could be simplified as a novel (3,4,4)-connected net with the point symbol of {83}4{84.102}2{86} which has not been reported in the literature (Fig 1c and Fig S5).
(Insert Fig. 1)
The PXRD pattern of the product is exactly the same as that of the simulated one from the crystal data, indicating its high phase purity (Fig S6). The thermal stability and the amount of guest molecules of 1 were evaluated by 4
ACCEPTED MANUSCRIPT thermogravimetric analysis (TGA). The TGA results indicated that all guest molecules (32.7%) of 1 can be removed at ca. 220°C and then the framework decomposition began to occur (Fig S7). Activation of DEF-containing samples of 1 by conventional heating in vacuum resulted in a non-porous material. Similar results were observed for the solvent-exchange activation method using dichloromethane, chloroform or alcohols like
PT
methanol or ethanol and then activated at low temperature. To address this problem, we use the supercritical CO2
RI
drying method to activate the anhydrous acetone-exchanged samples of 1. PXRD measurement shows that the
SC
crystallinity of the sample remains intact. In addition, the full activation of 1 has also been confirmed by the TGA data.
NU
In order to address the porosity of 1, gas sorption measurement was conducted. The N2 adsorption isotherm of
MA
activated 1 (1a) was measured at 77 K, which represents a typical reversible type I isotherm with a high adsorption capacity (Fig 2a). Based on the N2 isotherm, the Brunauer–Emmett–Teller (BET) surface area of 1a is about
D
1926 m2/g and the apparent Langmuir surface area is 2268 cm3/g. These values are comparable to those of the
PT E
highly porous MOFs such as MCF-19, NOTT-105, NOTT-125a and SNU-50 [20-22]. Meanwhile the pore volume is 0.98 cm3/g based on the maxim N2 uptake capacity. The fit of the adsorption data using the Horvath–Kawazoe
CE
method demonstrates the pore width distributes around about 0.6 and 1.1 nm (Fig S8). Establishment of perma-
AC
nent porosity prompts us to examine its utility as an adsorbent for CO2 capture. Accordingly, the CO2 sorption isotherms were collected up to 1 atm at two different temperatures of 273 K and 298 K. As shown in Fig. 2b, the isotherms are completely reversible and show no hysteresis. At 1 atm, 1a adsorbed CO2 of 102 and 58 cm3/g at 273 and 298 K, respectively, corresponding to about 40 and 22 CO2 molecules per unit cell. To understand the gas-framework interaction, the coverage dependent adsorption enthalpies were calculated using the virial-type expression equation by fitting the adsorption isotherms taken at 273 and 298 K to a Langmuir expression. 1a exhibits a Qst value of 26.3 kJ/mol at zero loading, which is similar to those of some highly porous MOFs, indicating
5
ACCEPTED MANUSCRIPT a moderate high CO2 binding ability [23-25]. It is well documented that open metal sites in MOFs are very beneficial for enhancing the adsorption capacities of gases [26]. (Insert Fig. 2)
PT
In summary, by utilizing a nanosized semi-rigid tripodal carboxylic acid ligand as the linker and a copper(II) paddlewheel as the SBU, we have successfully designed and constructed a new microporous Cu(II)-based MOF.
RI
In the structure of this MOF, there co-exist two types of 1D channels with different pore size (15 Å and 4.5 Å), which
SC
contributes to its high solvent-accessible free volume. Gas sorption studies confirm its high BET surface areas and ex-
PT E
D
MA
NU
cellent CO2 storage capacity around room temperature.
Appendix A. Supplementary material
CE
CCDC 1540952 (1) contains the supplementary crystallographic data for the title compound. This data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallo-
AC
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected]. Supplementary data associated with this article can be found, in the online version, at doi:
References [1] Y. Xiong, Y.-Z. Fan, R. Yang, S. Chen, M. Pan, J.-J. Jiang, C.-Y. Su, Chem. Commun. 50 (2014) 14631–14634. [2] Y. Ye, S. Xiong, X. Wu, L. Zhang, Z. Li, L. Wang, X. Ma, Q.-H. Chen, Z. Zhang, S. Xiang, Inorg. Chem. 55 (2016) 292–299.
6
ACCEPTED MANUSCRIPT [3] J.-M. Lin, C.-T. He, Y. Liu, P.-Q. Liao, D.-D. Zhou, J.-P. Zhang, X.-M. Chen, Angew. Chemie Int. Ed. 55 (2016) 4674–4678. [4] J. Liu, L. Chen, H. Cui, J. Zhang, L. Zhang, C.-Y. Su, Chem. Soc. Rev. 43 (2014) 6011–6061. [5] Q.-Y. Yang, K. Wu, J.-J. Jiang, C.-W. Hsu, M. Pan, J.-M. Lehn, C.-Y. Su, Chem. Commun. 50 (2014) 7702–7704. [6] Z.-W. Wei, C.-X. Chen, S.-P. Zheng, H.-P. Wang, Y.-N. Fan, Y.-Y. Ai, M. Pan, C.-Y. Su, Inorg. Chem. 55 (2016) 7311–7313.
PT
[7] X.-L. Yang, M.-H. Xie, C. Zou, Y. He, B. Chen, M. O’Keeffe, C.-D. Wu, J. Am. Chem. Soc. 134 (2012) 10638–10645.
RI
[8] H. Fei, J. Shin, Y.S. Meng, M. Adelhardt, J. Sutter, K. Meyer, S.M. Cohen, J. Am. Chem. Soc. 136 (2014)
SC
4965–4973.
[9] B.-B. Du, Y.-X. Zhu, M. Pan, M.-Q. Yue, Y.-J. Hou, K. Wu, L.-Y. Zhang, L. Chen, S.-Y. Yin, Y.-N. Fan,
NU
C.-Y. Su, Chem. Commun. 51 (2015) 12533–12536.
[10] Y.-X. Zhu, Z.-W. Wei, M. Pan, H.-P. Wang, J.-Y. Zhang, C.-Y. Su, Dalton. Trans. 45 (2016) 943–950. [11] G.-P. Li, G. Liu, Y.-Z. Li, L. Hou, Y.-Y. Wang, Z. Zhu, Inorg. Chem. 55 (2016) 3952–3959.
MA
[12] L. Hou, W.-J. Shi, Y.-Y. Wang, Y. Guo, C. Jin, Q.-Z. Shi, Chem. Commun. 47 (2011) 5464–5466. [13] H.-H. Wang, L.-N. Jia, L. Hou, W. Shi, Z. Zhu, Y.-Y. Wang, Inorg. Chem. 54 (2015) 1841–1846. [14] H.-C. Zhou, J.R. Long, O.M. Yaghi, Chem. Rev. 112 (2012) 673–674.
D
[15] L. Song, J. Zhang, L. Sun, F. Xu, F. Li, H. Zhang, X. Si, C. Jiao, Z. Li, S. Liu, Y. Liu, H. Zhou, D. Sun, Y.
PT E
Du, Z. Cao, Z. Gabelica, Energy Environ. Sci. 5 (2012) 7508–7520. [16] M. O’Keeffe, M.A. Peskov, S.J. Ramsden, O.M. Yaghi, Acc. Chem. Res. 41 (2008) 1782–1789. [17] Y.-B. Zhang, H. Furukawa, N. Ko, W. Nie, H.J. Park, S. Okajima, K.E. Cordova, H. Deng, J. Kim, O.M.
CE
Yaghi, J. Am. Chem. Soc. 137 (2015) 2641–2650. [18] Chui, S. S. Y.; Lo, S. M. F.; Charmant, J. P. H.; Orpen, A. G.; Williams, I. D. Science. 1999, 283 (5405),
AC
1148–1150.
[19] A.L. Spek, PLATON, a Multipurpose Crystallographic Tool, Untrecht University (2003). [20] Y.-B. Zhang, W.-X. Zhang, F.-Y. Feng, J.-P. Zhang, X.-M. Chen, Angew. Chemie Int. Ed. 48 (2009) 5287–5290.
[21] X. Lin, I. Telepeni, A.J. Blake, A. Dailly, C.M. Brown, J.M. Simmons, M. Zoppi, G.S. Walker, K.M. Thomas, T.J. Ma s, P. Hu
e s e , .R. Champness, M. Sch de , J. Am. Chem. Soc. 131 (2009) 2159–2171.
[22] N.H. Alsmail, M. Suyetin, Y. Yan, R. Cabot, C.P. Krap, J. Lü, T.L. Easun, E. Bichoutskaia, W. Lewis, A.J. Blake, M. Schröder, Chem. - A Eur. J. 20 (2014) 7317–7324. [23] F. Wang, Y. Tan, H. Yang, Y. Kang, J. Zhang, Chem. Commun. 48 (2012) 4842–4844.
7
ACCEPTED MANUSCRIPT [24] R. Luebke, J.F. Eubank, A.J. Cairns, Y. Belmabkhout, L. Wojtas, M. Eddaoudi, Chem. Commun. 48 (2012)
AC
CE
PT E
D
MA
NU
SC
RI
PT
1455–1457.
8
ACCEPTED MANUSCRIPT Captions for schemes and figures Fig. 1
(a) a representation for the formation of the network of 1; (b) the Connolly surface of 1 @1.8 Å; (c) the tiling of 1.
CE
PT E
D
MA
NU
SC
RI
PT
(a) 77 K N2 sorption isotherm for 1a; (b) CO2 sorption isotherms for 1a around room temperature.
AC
Fig. 2
9
D
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT E
Fig. 1
10
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT E
D
MA
NU
SC
Fig. 2
11
ACCEPTED MANUSCRIPT
AC
CE
PT E
D
MA
NU
SC
RI
PT
Graphical Abstract-Pictogram
12
ACCEPTED MANUSCRIPT
PT
Graphical Abstract-Synopsis
semi-rigid tripodal carboxylic acid ligand and binuclear Cu(II) units.
SC
[Cu3(cpbda)2(H2O)3](DEF)4, by using a
RI
We designed, synthesized, and characterized a new Cu(II)-based metal–organic framework material,
NU
This MOF features a novel (3,4,4)-connected network with the point symbol {83}4{84.102}2{86} which has not been observed in MOF chemistry. The co-existing of the circular channels (15 Å) and quadrate channels (4.5 Å)
MA
contributes to its high pore and Brunauer–Emmett–Teller (BET) surface area. In addition, In addition, the acti-
AC
CE
PT E
D
vated MOF also shows excellent CO2 storage capacity around room temperature.
13
ACCEPTED MANUSCRIPT
Research Highlights for
A new porous Cu(II)-based MOF was synthesized.
SC
RI
Two different types of 1D channels co-exist in the structure.
PT
Inorg. Chem. Commun.
AC
CE
PT E
D
MA
NU
High BET surface area and excellent CO2 adsorption capacity could be observed.
14
Baohui Liu, Xin Li, Shengjun Dong, Mingkai Li, Yujiu Wang PII: DOI: Reference:
S1387-7003(17)30253-8 doi: 10.1016/j.inoche.2017.04.011 INOCHE 6616
To appear in:
Inorganic Chemistry Communications
Received date: Revised date: Accepted date:
31 March 2017 13 April 2017 15 April 2017
Please cite this article as: Baohui Liu, Xin Li, Shengjun Dong, Mingkai Li, Yujiu Wang , Synthesis, structure and gas adsorption properties of a microporous metal–organic framework assembled from a semi-rigid tripodal carboxylic acid ligand. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Inoche(2017), doi: 10.1016/j.inoche.2017.04.011
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Synthesis, structure and gas adsorption properties of a microporous metal–organic framework assembled from a semi-rigid tripodal carboxylic acid li-
PT
gand
Department of Cardiac Surgery, Binzhou Medical University Hospital, Binzhou Medical Univer-
SC
1
RI
Baohui Liu1§, Xin Li2§, Shengjun Dong1, Mingkai Li3, Yujiu Wang1*
sity, Binzhou, Shandong, China
Department of Pharmacology, School of Pharmacy, the Fourth Military Medical University, Xi’an,
MA
3
Department of gynecology, Binzhou People`s Hospital, Binzhou, Shandong, China
NU
2
AC
CE
PT E
D
China
§
These authors contributed equally to this paper.
* Corresponding author. E-mail address: [email protected].
Inorg. Chem. Commun
1
ACCEPTED MANUSCRIPT
Abstract. The design, synthesis, and structural characterization of a new cubic three-dimensional microporous metal–organic
framework
featuring
a
semi-rigid
tripodal
carboxylic
acid
ligand,
4,4′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda), is reported. Single-crystal X-ray diffraction analysis indicates that compound 1 possesses a novel (3,4,4)-connected network with the point symbol of {83}4{84.102}2{86}. In the framework of 1, there co-exist two types of 1D channels with different pore size (15 Å
PT
and 4.5 Å). The pore characteristics and gas sorption properties of this compound were investigated both at cryogenic temperatures and room temperature by experimentally measuring N2 and CO2 sorption isotherms. These
RI
studies show that compound 1 is highly porous with a pore volume of 0.98 cm3/g and BET surface of 1926 cm3/g.
Cu(II)-based MOF; (3,4,4)-connected topology; hierarchical porosity; gas sorption
MA
NU
Keywords:
SC
In addition, the activated 1 also shows excellent CO2 storage capacity around room temperature.
As an emerging class of hybrid crystalline materials, metal–organic frameworks (MOFs) that are self-assembled
D
from metal ions or clusters with organic ligands have attracted considerable attention owing to their great potential
PT E
in a wide variety of applications such as gas storage/separation, sensor, catalysis and fluorescent material [1-13]. Among the diverse applications of MOFs, gas storage and separation will probably play a key role in future due to
CE
the rising energy- and environment-related issues faced by our society [14]. The extremely high surface areas, adjustable pore sizes, as well as intriguing functionalities make them more competitive over other traditional ad-
AC
sorbent materials, such as zeolites, activated carbons, or diatomite. The ability to rationally design and modify the crystal structures of MOF materials is the key to achieve high adsorption capacity and selectivity to meet specific storage/separation needs and to increase the potential for commercial applications [15]. One particularly useful and extensively studied strategy in forming porous structures with controlled topology, large pore volume, and framework integrity is to make use of secondary building units (SBU) with different shapes, sizes, and binding modes [16]. For example, a family of highly porous MOFs have been constructed using Zn4O(COO)6 as the SBU
2
ACCEPTED MANUSCRIPT [17]. The octahedral geometry and six-fold connectivity of this SBU leads to a cubic structure. The paddle-wheel unit Cu2(COO)4(L2) is another type of SBU with a slightly different topology and connectivity from Zn4O(COO)6, typically resulting in a tetragonal (distorted cubic) structure. By simply varying the length of organic linkers, isostructural compounds with a range of pore space can be obtained with the same SBU. However, the increasing the
PT
length of ligand usually accompanies with framework interpenetration, which is not beneficial for obtaining high-
RI
ly porous MOFs. For instance, the combination of Cu2(COO)4 unit with H3BTC ligand affords the famous
SC
HKUST-1 [18]; when replacing the H3BTC ligand with the H3BTB ligand, Cu3(BTB)2 (MOF-14) with similar
NU
framework connection but 2-fold interpenetrated network was obtained [19].
In this study, we present the synthesis, structure and gas sorption properties of a novel non-interpenetrating cpbda
with a high pore volume and BET surface that constructed
MA
Cu(II)-based MOF
from the binuclear Cu2(COO)4 unit and a semi-rigid tripodal carboxylic acid. In the framework of this compound,
D
there exist two types of 1D channels along the c axis, one with a pore diameter of 15 Å and the other features a
PT E
pore diameter of 4.5 Å. We explored the porosity and gas sorption capacity of compound 1. The N2 adsorption at
CE
77 K shows compound 1 is microporous with BET surface of
AC
Single-crystal X-ray structural analysis shows that compound 1 possesses a 3D neutral framework and crystallizes in the tetragonal space group P4/nnc. The asymmetric unit of 1 contains three independent Cu atoms (Cu2 and Cu3 with an occupancy of 0.25), two coordinated water molecules and one fully deprotonated cpbda3- ligand (Fig S1). All the Cu2+ ions in 1 are five-coordinated by four carboxylic O atoms from four different cpbda3ligands and one O atom from a water molecule, resulting in a tetragonal pyramidal geometry. The Cu-O bond distances are in the range of 1.995(5) to 2.196(8) Å. The distance between Cu1 and Cu1A, Cu2 and Cu3 is 2.612(2) and 2.633(2) Å, respectively. There are two different binuclear Cu2+ units in the framework of 1, one is formed by 3
ACCEPTED MANUSCRIPT the Cu1 and Cu1A atoms and the other consists of the Cu2 and Cu3 atoms (Fig S2). The two benzene ring arms of the cpbda3- ligand bend significantly, resulting in a T-shape molecular geometry. The dihedral angles between the o
o
central benzene ring and the two side benzene rings are 77.9(7) (left) and 93.6(3) (right) (Fig S3). The most no-
ticeable structural feature of 1 is the co-existing of interlacing circular channels and quadrate channels with two
PT
different sizes (15 Å and 4.5 Å, Fig 1a). The larger one is formed by four paddle-wheel units and eight long arms
RI
from eight different cpbda3- ligands; the smaller one is shaped by two paddle-wheel units, two short arms and two
SC
long arms of the cpbda3- ligands. Moreover, we can find unique 1D helical chains running along c axis in the structure of 1. The helix is constructed by one short arm and one long arm of the adjacent cpbda3- ligands that connected by
NU
the paddle-wheel units, displaying left-handed and right-handed helical chains, with the pitch of the helix being 10.86(2)
MA
Å (Fig S4). Each large channel is surrounded by the eight small channels and each small channel is nearby two large channels. So the whole framework of 1 could be also regarded as a packing of small quadrate channels and
D
large circular channels in the ratio of 2:1 along the c axis. The total void volume available to guest molecules in 1
PT E
was estimated by PLATON/SOLV (probe radius of 1.2 Å) calculations to be 71.5% of the total crystal volume (Fig 1b), and low crystallography density of 0.64 g/cm3, corresponding to a theoretical pore volume of 1.12 cm3/g
CE
[19]. The free spaces are occupied by the structurally disordered solvent molecules. Topology analysis is applied
AC
in order to better understand the structure of compound 1. If the binuclear Cu units are viewed as 4-connected nodes and cpbda3- ligand could be judged as a 3-connected node, so the resulting structure of compound 1 could be simplified as a novel (3,4,4)-connected net with the point symbol of {83}4{84.102}2{86} which has not been reported in the literature (Fig 1c and Fig S5).
(Insert Fig. 1)
The PXRD pattern of the product is exactly the same as that of the simulated one from the crystal data, indicating its high phase purity (Fig S6). The thermal stability and the amount of guest molecules of 1 were evaluated by 4
ACCEPTED MANUSCRIPT thermogravimetric analysis (TGA). The TGA results indicated that all guest molecules (32.7%) of 1 can be removed at ca. 220°C and then the framework decomposition began to occur (Fig S7). Activation of DEF-containing samples of 1 by conventional heating in vacuum resulted in a non-porous material. Similar results were observed for the solvent-exchange activation method using dichloromethane, chloroform or alcohols like
PT
methanol or ethanol and then activated at low temperature. To address this problem, we use the supercritical CO2
RI
drying method to activate the anhydrous acetone-exchanged samples of 1. PXRD measurement shows that the
SC
crystallinity of the sample remains intact. In addition, the full activation of 1 has also been confirmed by the TGA data.
NU
In order to address the porosity of 1, gas sorption measurement was conducted. The N2 adsorption isotherm of
MA
activated 1 (1a) was measured at 77 K, which represents a typical reversible type I isotherm with a high adsorption capacity (Fig 2a). Based on the N2 isotherm, the Brunauer–Emmett–Teller (BET) surface area of 1a is about
D
1926 m2/g and the apparent Langmuir surface area is 2268 cm3/g. These values are comparable to those of the
PT E
highly porous MOFs such as MCF-19, NOTT-105, NOTT-125a and SNU-50 [20-22]. Meanwhile the pore volume is 0.98 cm3/g based on the maxim N2 uptake capacity. The fit of the adsorption data using the Horvath–Kawazoe
CE
method demonstrates the pore width distributes around about 0.6 and 1.1 nm (Fig S8). Establishment of perma-
AC
nent porosity prompts us to examine its utility as an adsorbent for CO2 capture. Accordingly, the CO2 sorption isotherms were collected up to 1 atm at two different temperatures of 273 K and 298 K. As shown in Fig. 2b, the isotherms are completely reversible and show no hysteresis. At 1 atm, 1a adsorbed CO2 of 102 and 58 cm3/g at 273 and 298 K, respectively, corresponding to about 40 and 22 CO2 molecules per unit cell. To understand the gas-framework interaction, the coverage dependent adsorption enthalpies were calculated using the virial-type expression equation by fitting the adsorption isotherms taken at 273 and 298 K to a Langmuir expression. 1a exhibits a Qst value of 26.3 kJ/mol at zero loading, which is similar to those of some highly porous MOFs, indicating
5
ACCEPTED MANUSCRIPT a moderate high CO2 binding ability [23-25]. It is well documented that open metal sites in MOFs are very beneficial for enhancing the adsorption capacities of gases [26]. (Insert Fig. 2)
PT
In summary, by utilizing a nanosized semi-rigid tripodal carboxylic acid ligand as the linker and a copper(II) paddlewheel as the SBU, we have successfully designed and constructed a new microporous Cu(II)-based MOF.
RI
In the structure of this MOF, there co-exist two types of 1D channels with different pore size (15 Å and 4.5 Å), which
SC
contributes to its high solvent-accessible free volume. Gas sorption studies confirm its high BET surface areas and ex-
PT E
D
MA
NU
cellent CO2 storage capacity around room temperature.
Appendix A. Supplementary material
CE
CCDC 1540952 (1) contains the supplementary crystallographic data for the title compound. This data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallo-
AC
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected]. Supplementary data associated with this article can be found, in the online version, at doi:
References [1] Y. Xiong, Y.-Z. Fan, R. Yang, S. Chen, M. Pan, J.-J. Jiang, C.-Y. Su, Chem. Commun. 50 (2014) 14631–14634. [2] Y. Ye, S. Xiong, X. Wu, L. Zhang, Z. Li, L. Wang, X. Ma, Q.-H. Chen, Z. Zhang, S. Xiang, Inorg. Chem. 55 (2016) 292–299.
6
ACCEPTED MANUSCRIPT [3] J.-M. Lin, C.-T. He, Y. Liu, P.-Q. Liao, D.-D. Zhou, J.-P. Zhang, X.-M. Chen, Angew. Chemie Int. Ed. 55 (2016) 4674–4678. [4] J. Liu, L. Chen, H. Cui, J. Zhang, L. Zhang, C.-Y. Su, Chem. Soc. Rev. 43 (2014) 6011–6061. [5] Q.-Y. Yang, K. Wu, J.-J. Jiang, C.-W. Hsu, M. Pan, J.-M. Lehn, C.-Y. Su, Chem. Commun. 50 (2014) 7702–7704. [6] Z.-W. Wei, C.-X. Chen, S.-P. Zheng, H.-P. Wang, Y.-N. Fan, Y.-Y. Ai, M. Pan, C.-Y. Su, Inorg. Chem. 55 (2016) 7311–7313.
PT
[7] X.-L. Yang, M.-H. Xie, C. Zou, Y. He, B. Chen, M. O’Keeffe, C.-D. Wu, J. Am. Chem. Soc. 134 (2012) 10638–10645.
RI
[8] H. Fei, J. Shin, Y.S. Meng, M. Adelhardt, J. Sutter, K. Meyer, S.M. Cohen, J. Am. Chem. Soc. 136 (2014)
SC
4965–4973.
[9] B.-B. Du, Y.-X. Zhu, M. Pan, M.-Q. Yue, Y.-J. Hou, K. Wu, L.-Y. Zhang, L. Chen, S.-Y. Yin, Y.-N. Fan,
NU
C.-Y. Su, Chem. Commun. 51 (2015) 12533–12536.
[10] Y.-X. Zhu, Z.-W. Wei, M. Pan, H.-P. Wang, J.-Y. Zhang, C.-Y. Su, Dalton. Trans. 45 (2016) 943–950. [11] G.-P. Li, G. Liu, Y.-Z. Li, L. Hou, Y.-Y. Wang, Z. Zhu, Inorg. Chem. 55 (2016) 3952–3959.
MA
[12] L. Hou, W.-J. Shi, Y.-Y. Wang, Y. Guo, C. Jin, Q.-Z. Shi, Chem. Commun. 47 (2011) 5464–5466. [13] H.-H. Wang, L.-N. Jia, L. Hou, W. Shi, Z. Zhu, Y.-Y. Wang, Inorg. Chem. 54 (2015) 1841–1846. [14] H.-C. Zhou, J.R. Long, O.M. Yaghi, Chem. Rev. 112 (2012) 673–674.
D
[15] L. Song, J. Zhang, L. Sun, F. Xu, F. Li, H. Zhang, X. Si, C. Jiao, Z. Li, S. Liu, Y. Liu, H. Zhou, D. Sun, Y.
PT E
Du, Z. Cao, Z. Gabelica, Energy Environ. Sci. 5 (2012) 7508–7520. [16] M. O’Keeffe, M.A. Peskov, S.J. Ramsden, O.M. Yaghi, Acc. Chem. Res. 41 (2008) 1782–1789. [17] Y.-B. Zhang, H. Furukawa, N. Ko, W. Nie, H.J. Park, S. Okajima, K.E. Cordova, H. Deng, J. Kim, O.M.
CE
Yaghi, J. Am. Chem. Soc. 137 (2015) 2641–2650. [18] Chui, S. S. Y.; Lo, S. M. F.; Charmant, J. P. H.; Orpen, A. G.; Williams, I. D. Science. 1999, 283 (5405),
AC
1148–1150.
[19] A.L. Spek, PLATON, a Multipurpose Crystallographic Tool, Untrecht University (2003). [20] Y.-B. Zhang, W.-X. Zhang, F.-Y. Feng, J.-P. Zhang, X.-M. Chen, Angew. Chemie Int. Ed. 48 (2009) 5287–5290.
[21] X. Lin, I. Telepeni, A.J. Blake, A. Dailly, C.M. Brown, J.M. Simmons, M. Zoppi, G.S. Walker, K.M. Thomas, T.J. Ma s, P. Hu
e s e , .R. Champness, M. Sch de , J. Am. Chem. Soc. 131 (2009) 2159–2171.
[22] N.H. Alsmail, M. Suyetin, Y. Yan, R. Cabot, C.P. Krap, J. Lü, T.L. Easun, E. Bichoutskaia, W. Lewis, A.J. Blake, M. Schröder, Chem. - A Eur. J. 20 (2014) 7317–7324. [23] F. Wang, Y. Tan, H. Yang, Y. Kang, J. Zhang, Chem. Commun. 48 (2012) 4842–4844.
7
ACCEPTED MANUSCRIPT [24] R. Luebke, J.F. Eubank, A.J. Cairns, Y. Belmabkhout, L. Wojtas, M. Eddaoudi, Chem. Commun. 48 (2012)
AC
CE
PT E
D
MA
NU
SC
RI
PT
1455–1457.
8
ACCEPTED MANUSCRIPT Captions for schemes and figures Fig. 1
(a) a representation for the formation of the network of 1; (b) the Connolly surface of 1 @1.8 Å; (c) the tiling of 1.
CE
PT E
D
MA
NU
SC
RI
PT
(a) 77 K N2 sorption isotherm for 1a; (b) CO2 sorption isotherms for 1a around room temperature.
AC
Fig. 2
9
D
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT E
Fig. 1
10
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT E
D
MA
NU
SC
Fig. 2
11
ACCEPTED MANUSCRIPT
AC
CE
PT E
D
MA
NU
SC
RI
PT
Graphical Abstract-Pictogram
12
ACCEPTED MANUSCRIPT
PT
Graphical Abstract-Synopsis
semi-rigid tripodal carboxylic acid ligand and binuclear Cu(II) units.
SC
[Cu3(cpbda)2(H2O)3](DEF)4, by using a
RI
We designed, synthesized, and characterized a new Cu(II)-based metal–organic framework material,
NU
This MOF features a novel (3,4,4)-connected network with the point symbol {83}4{84.102}2{86} which has not been observed in MOF chemistry. The co-existing of the circular channels (15 Å) and quadrate channels (4.5 Å)
MA
contributes to its high pore and Brunauer–Emmett–Teller (BET) surface area. In addition, In addition, the acti-
AC
CE
PT E
D
vated MOF also shows excellent CO2 storage capacity around room temperature.
13
ACCEPTED MANUSCRIPT
Research Highlights for
A new porous Cu(II)-based MOF was synthesized.
SC
RI
Two different types of 1D channels co-exist in the structure.
PT
Inorg. Chem. Commun.
AC
CE
PT E
D
MA
NU
High BET surface area and excellent CO2 adsorption capacity could be observed.
14