2D halogen-bonded organic frameworks were readily engineered by strong and directional effects of the primary Br⋯O and the secondary Br⋯π halogen bonding interactions from the tetrabromobenzene-1,4-dicarboxylic acid building molecule involving 100% supramolecular yields.
Halogen bonding is one of the most interesting noncovalent attractions capable of self-assembly and recognition processes in both solution and solid phase. In this contribution, we report on the formation of two solvates of tetrabromoterephthalic acid (H2Br4tp) with acetonitrile (MeCN) and methanol (MeOH) viz. H2Br4tp·2MeCN (1MeCN) and H2Br4tp·2MeOH (2MeOH). The host structures of both 1MeCN and 2MeOH are assembled via the occurrence of simultaneous Br···Br, Br···O, and Br···π halogen bonding interactions, existing between the H2Br4tp molecular tectons. Among them, the cooperative effect of the dominant halogen bond in combination with hydrogen bonding interactions gave rise to different supramolecular assemblies, whereas the strength of the halogen bond depends on the type of hydrogen bond between the molecules of H2Br4tp and the solvents. These materials show a reversible release/resorption of solvent molecules accompanied by evident crystallographic phase transitions.
Two new lanthanide-based coordination polymers, [Sm2(bzz)(ben)6(H2O)3]·0.5H2O (1) and [Eu(bbz)(ben)3] (2), were synthesized and characterized. The described products were formed from in situ-generated benzoate (ben) and N’-benzoylbenzohydrazide (bbz) ligands, which were the products of transformation of originally added benzhydrazide (bzz) under hydrothermal conditions. Compound 1 exhibits a one-dimensional (1D) double-chain structure built up from the connection of the central Sm3+ ions with a mixture of bzz and ben ligands. On the other hand, 2 features a 3D network with a 4-connected (66) dia topology constructed from dinuclear [Eu2(ben)6] secondary building units and bbz linkers. High-pressure CO2 sorption studies of activated 1 show that maximum uptake increases to exceptionally high values of 376.7 cm3 g−1 (42.5 wt%) under a pressure of 50 bar at 298 K with good recyclability. Meanwhile, 2 shows a typical red emission in the solid state at room temperature with the decay lifetime of 1.2 ms.
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