The construction of metal±organic framework (MOF) coordination polymers is currently receiving considerable attention owing to their potential properties as functional solid materials, as well as their fascinating framework structures. [1±3] Particularly widely explored have been MOFs with porous chiral structures in which chiral ligands, chiral templates, or chiral functionalization of achiral zeolites are used to perform enantioselective separations and syntheses. [4±7] It is challenging to prepare chiral MOF materials with known chiral topology from an achiral building unit.
Learning from nature©s minerals, and utilizing the welldefined coordination geometries of metal centers, some structures of minerals with specific functionality, such as perovsktie, [8] rutile, [9] PtS, [10] and feldspar [11] have been artificially produced by replacing monoatomic anions (O 2À , S 2À ) with polyatomic organic m ligands. The quartz phase, which is chiral, has unique piezoelectricity and thermally sensitive properties and is widely used in resonators and sensors. [12] Although the SiO 2 phase with quartz topology is thermodynamically more stable than cristobalite which has diamond topology, in nature or in artificial materials, known phases which have quartz topology are rare with only one example, a cyano-bridged coordination polymer, reported by Robson and co-workers. [13] Generally, most materials comprising fourconnected tetrahedral (T) units, including MOFs, exist in the diamond topology, [1c,d, 14] rather than the quartz topology, while SiO 2 and GeO 2 are minerals that have both a quartz polymorph and cristobalite with diamond topology. Interestingly, when cristobalite is quenched to room temperature, [15] it is transformed reconstructively to the quartz polymorph.
Herein we report the preparation of two quartzlike, chiral, open MOFs, Zn(ISN) 2 ¥2 H 2 O (ISN ¼ isonicotinate), assigned QMOF-1, with the low symmetry of a-quartz and InH(BDC) 2 (BDC ¼ terephthalate), QMOF-2, with the high symmetry of b-quartz. QMOF-1 with a large (~8.6 ä) left-handed channel was successfully synthesized with an asymmetric ISN ligand by using a low-temperature diffusion method (room temperature) similar to the preparation of metal carboxylate [17] . On using a highly distorted complex anion [In(O 2 CR) 4 ] À as the T block, [16] and terephthalate as a linear rod, we could assemble the anion-type b-quartzlike network QMOF-2 with a right-handed channel (~7.8 ä).
The preparation of QMOF-1 was carried out in a wide range of conditions: Zn(NO 3 ) 2 ¥6 H 2 O: 1.5±3.0 ISN: 1±10 triethylamine (TEA): 5±10 000 dimethylsulfoxide (DMSO): 0±20 000 ethanol. After one week, large colorless needlelike single crystals with dimensions up to 0.200 î 0.200 î 3 mm were obtained quantitatively (relative to Zn). QMOF-2 was solvothermally obtained from InCl 3 :terephthalate (1:2) at 160 8C for 3 days, yield 60 % (relative to In). The IR spectra showed that the carboxylate group in QMOF-1 has monodentate coordination to the metal center, while that in QMOF-2 is bidentate. [18] The single-crystal X-ray diffraction studies reveal that all the zinc ions in QMOF-1 are four-coordinate (Figure 1 a). [19] Each Zn atom is coordinated by two nitrogen atoms of two ISN ligands and two oxygen atoms of two carboxylate groups from two other ISN ligands. All of the T units are slightly distorted, the ZnÀO and ZnÀN bonds are 1.95 and 2.02 ä, respectively, and the angles of N(1)-Zn(1)-N(2), N(1)-Zn(1)-O(2), N(1)-Zn(1)-O(1), O(1)-Zn(1)-O(2) are 113.5, 117.5, 104.9, 100.48, respectively. The 3D twofold interpenetrated network with T blocks is characteristic of a 6 4 8 2 -b net, similar to that of a-quartz (Figure 2, Figure S1 in the supporting information). [1c] In the QMOF-1 structure, large Zn cations replace the Si atoms in quartz structure, and the long ISN anions replace the O atoms, so that the separation between two T units can be expanded to 8.813 ä, only slightly different from the Zn±Zn separations in the diamondoid network ZUSCHRIFTEN