Two Robust Porous Metal–Organic Frameworks Sustained by Distinct Catenation: Selective Gas Sorption and Single‐Crystal‐to‐Single‐Crystal Guest Exchange

Abstract

Assembly of copper(I) halide with a new tripodal ligand, benzene-1,3,5-triyl triisonicotinate (BTTP4), afforded two porous metal-organic frameworks, [Cu(2)I(2)(BTTP4)]⊃2CH(3)CN (1·2CH(3)CN) and [CuBr(BTTP4)]⊃(CH(3)CN·CHCl(3)·H(2)O) (2·solvents), which have been characterized by IR spectroscopy, thermogravimetry (TG), single-crystal, and powder X-ray diffraction (PXRD) methods. Compound 1 is a polycatenated 3D framework that consists of 2D (6,3) networks through inclined catenation, whereas 2 is a doubly interpenetrated 3D framework possessing the ThSi(2)-type (ths) (10,3)-b topology. Both frameworks contain 1D channels of effective sizes 9×12 and 10×10 Å(2), which amounts to 43 and 40% space volume accessible for solvent molecules, respectively. The TG and variable-temperature PXRD studies indicated that the frameworks can be completely evacuated while retaining the permanent porosity, which was further verified by measurement of the desolvated complex [Cu(2)I(2)(BTTP4)] (1'). The subsequent guest-exchange study on the solvent-free framework revealed that various solvent molecules can be adsorbed through a single-crystal-to-single-crystal manner, thus giving rise to the guest-captured structures [Cu(2)I(2)(BTTP4)]⊃C(6)H(6) (1·benzene), [Cu(2)I(2)(BTTP4)]⊃2C(7)H(8) (1·2 toluene), and [Cu(2)I(2)(BTTP4)]⊃2C(8)H(10) (1·2 ethylbenzene). The gas-adsorption investigation disclosed that two kinds of frameworks exhibited comparable CO(2) storage capacity (86-111 mL g(-1) at 1 atm) but nearly none for N(2) and H(2), thereby implying its separation ability of CO(2) over N(2) and H(2). The vapor-adsorption study revealed the preferential inclusion of aromatic guests over nonaromatic solvents by the empty framework, which is indicative of selectivity toward benzene over cyclohexane.

Finding a New Crystalline Sponge from a Crystallographic Database

“…Solvent exchange of hostcrystals of 2w ith CS 2 Host crystals of 2 were synthesized in test tubes on a2 0-mg scale in chloroform/acetonitrile according to the reported procedure. [9] After the mother liquor was removed by decantation, the crystals were washed by addition and decantation of CS 2 (5 5mL). The crystals were then soaked in fresh CS 2 (10 mL) in at est tube for 2d at room temperature.…”

“…Host crystals of 2 were synthesized in test tubes on a 20‐mg scale in chloroform/acetonitrile according to the reported procedure . After the mother liquor was removed by decantation, the crystals were washed by addition and decantation of CS 2 (5×5 mL).…”

“…Single-crystal X-ray analysisc learly showedt hat molecules of guest 3 were trapped in the 1D channel of host 2 (Figure 4), forming two columns along the b-axis. [11] Although the space group changed from P2/n (reported by Yang et al) [9] to P2 1 / c upon guest inclusion, the network structure of host 2 was essentially the same as its as-synthesized form. The carbonyl group of guest 3 was doubly hydrogen-bonded by two C arom À Hp rotons of host 2,w hich resulted in as lightly non-planar conformation of 3 (the dihedrala ngles between the aromatic ring and the acetyl group were 30.7(4)8 and 38.8(4)8 for the two crystallographicallyi nequivalent molecules of guest 3).…”

Porous zinc(II)-organic framework with potential open metal sites: Synthesis, structure and property

“…Nevertheless, the metal sites are coordinatively saturated in these structures. In order to achieve MOFs with structure avoiding formation of {Zn 4 O(O 2 C) 6 the free coordinated carboxamide group can serve as hydrogen bonding acceptors and donors, which may increase the stability of the porous structure; and (4) the coplanar rigidity of the ligand with acyl can significantly increase the interaction between the gas or guest molecules and pore internal surface thus enhancing the adsorption quantity [13][14][15][16][17][18][19][20][21][22] …”

Assembly and Crystal Structure of a 2D lead(II) Coordination Polymer with 1D Metal–Oxygen Chains

“…Coordination polymers, or metal-organic frameworks (MOFs) constructed from metal nodes and organic linkers as organic-inorganic hybrid solids, have received much attention not only on account of their potential applications in uminescencent, magnetic, sorption, and catalytic materials, [1][2][3] but also due to their intriguing topologies and structural types. [4][5][6][7][8][9] Nevertheless, most experimental and theoretical studies for MOFs has been concentrated on the deliberate control of coordination networks via selecting organic ligands, metal ions, solvent system, etc., especially new organic linkers contributing to the occurrence of the varieties of novel polymers.…”