Copper(II) camphorates with tunable pore size in metal-organic frameworks

Abstract

Three new homochiral metal organic coordination polymers [Cu 2 camph 2 dabco]•DMF•2H 2 O, [Cu 2 camph 2 bipy]•3DMF•2H 2 O, and [Cu 2 camph 2 bpe]•4DMF•2H 2 O (H 2 camph is (+) cam phoric acid, bipy is 4,4′ bipyridyl, bpe is trans bis(4 pyridyl)ethylene) were synthesized by heating copper(II) nitrate, (+) camphoric acid, and N donor ligands of different length (dabco, bipy, bpe) in DMF and characterized by powder X ray diffraction, IR spectroscopy, and TGA. The obtained compounds are isostructural with the previously reported porous zinc(II) cam phorates.Porous metal organic coordination polymers belong to a new class of compounds whose inorganic and organic building blocks are arranged so that an organic ligand bridges the metal cations in a hybrid framework. 1-4 Tre mendous interest in these compounds is due to that they offer many ways of the functional design of coordination polymers and thus can be used to prepare new materias. 5,6 In particular, optically pure ligands give structures with the same configuration of chiral centers. Such coordina tion polymers are referred to as enantiomerically pure (homochiral). 7 Porous homochiral coordination polymers are regarded as promising materials for the separation or purification of enantiomers in complex mixtures 8-11 and for the enantioselective catalysis. 12-15 Of particular interest in this regard is the synthesis of diverse families of porous homochiral frameworks with changeable metal atoms and tunable pore size for the selective sorption/ activation of the molecules of only the desired size and configuration. Synthesis of porous homochiral coordina tion polymers poses challenges and is essentially restricted by the selection of the constituent organic ligands. The traditional approach exploits ligands, which are required to be chiral and simultaneously possess a sufficient length and steric rigidity to impart porosity and stability to the structure. 7 Organic compounds featuring all the above properties are often poorly available or are difficult to synthesize. Recently 8 we have proposed a strategy for the construction of porous homochiral coordination poly mers that allows the control of the structural parameters (pore size and the configuration of chiral centers) of the metal organic frameworks. The strategy is based on a com bination of two simple ligands: a small chiral multimodal ligand forming chiral complexes with the metal cations and a rigid bridging ligand assembling these complexes into a porous framework. One of the advantages of our method is the usage of relatively simple and available enantiomerically pure ligands. Following this strategy, we have for the first time prepared a range of homochiral frameworks 16 with the tunable pore size based on zinc(II), (+) camphoric acid (H 2 camph), and rigid bridging ligands of different length (dabco (diazabicyclo[2.2.2]octane), bipy (4,4´ bipyridyl), and bpe (trans bis(4 pyridyl) ethylene).Here we report synthesis and powder X ray diffraction study of three novel coordination polymers (copper(II)

Binary co-crystals of the active pharmaceutical ingredient 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene and camphoric acid

“…The bioavailability and non-toxic nature of cam makes it a suitable candidate for pharmaceutical preparations. It has been extensively studied and used as a precursor for coordination polymer/MOF synthesis (Smart et al, 2013;Thuery, 2009;Dybtsev et al, 2009;Blake et al, 2012;Chen et al, 2009;Wu et al, 2010). The physiological effects of cam are described and exploited in a few reports (Lima et al, 2012), which essentially indicate the potential of cam as a co-crystal former.…”

Enantioselective adsorption in homochiral metal–organic frameworks: the pore size influence

“…There are occasional reports that the pore size has a substantial impact on the adsorption capacity and also on the selectivity of achiral MOFs. [20][21][22] A few publications [23][24][25][26][27] investigate the enantioselectivity of different chiral MOFs with tunable structures, however, a systematic study of the impact of the pore size of the chiral MOFs on the enantioselectivity has not yet been carried out. Here, we investigate the influence of the pore size of isoreticular chiral MOFs (i.e.…”