Framework solids with chiral structures

The construction of novel coordination polymers is a current interest in the field of supramolecular chemistry and crystal engineering, stemming from their potential applications as frinctional materials as well as their intriguing variety of architectures and molecular topologies. In particular, solid materials with either helical or chiral structures are of intense interest in chemistry and material science. Although solid materials with imusual structures are expected to increase in number, the exploration for preparing framework solids with chiral structures still remains a challenge. Thermal analysis is a fundamental tool for the characterization of these new coordination polymeric compounds. 

Xiong et al. also demonstrated that the chiral 2D framework [Cu(PPhj)(A,A( -(2-pyridyl-(4-pyridyl methyl)-amine)),5] C10 (9), with triangular cavities, synthesized from achiral components, [Cu(MeCN)j(PPh3)J[C10 ] and N,N -(2-pyridyl-(4-pyridyl methyl)-amine) can enantioselectively include 2-butanol [76]. Spontaneous resolution produced crystalline inclusion compound 91.5(2-butanol), which was structurally characterized. They manually separated the enantiomorphic forms of 91.5(2-butanol) according to their CD spectra in solid state and evacuated at 100°C to collect enantiopure 2-butanol. Although this work provides an economical route to enantioselective separation of racemic small diols, the separation... 

The diversity of ordered porous solids increases at an astonishing rate, particularly among the readily crystallised MOFs, and continues to olfer novel materials properties. There is no obvious barrier to the synthesis of a myriad of new zeolite, zeotype or hybrid structures. Challenges remain, however. For zeolitic aluminosilicates, the 10 A pore size restriction remains an important barrier, and an enantiomerically pure zeolite is still out of reach. For nonsilicate crystalline microporous solids, thermal and hydrothermal stability, rather than framework geometry, limit their applicability, since fully crystalline germanates and carboxylates with pores in the mesoporous range now exist, and these solids have enormous specific surface areas. In these hybrid solids the ability to choose chirality in the building units indicates that it will be possible to prepare these in chiral form the first examples have already been prepared. 

Pillar[5]arenes can rotate freely around every terphenylene linker, which results in the disorder within P5A-MOF-1 itself. On the other hand, the random distribution of enantiomeric pillar[5]arenes corresponding to their planar chirality also contributes to the disorder. Therefore, singlecrystal X-ray data is unable to discern the solid structure of P5A-MOF-1 as the extended framework. Non-interpenetrated IRMOF-16, incorporated with pillar[5]arenes with randomly distributed chirality and orientations around... 

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