Halogen···Halogen Interactions in the Supramolecular Assembly of 2D Coordination Polymers and the CO₂ Sorption Behavior

Abstract

Four new mixed-ligand divalent coordination polymers (CPs) [Cu2­(muco)2­(4-clpy)2] (1), [Cu2­(muco)2­(4-brpy)2] (2), [Zn2­(bdc)2­(4-clpy)2] (3), and [Zn2­(bdc)2­(4-brpy)2] (4) (H2muco = trans,trans-muconic acid or 1,3-butadiene-1,4-dicarbox­ylic acid; H2bdc = 1,4-benzene dicarbox­ylic acid; 4-clpy = 4-chloro­pyridine and 4-brpy = 4-bromo­pyridine) have been synthesized and well characterized by elemental analysis, infrared spectra, single-crystal X-ray diffraction techniques, powder X-ray diffraction patterns, and thermogravimetric analysis. All the compounds 1–4 have a two-dimensional (2D) coordination polymeric sheet structure. Of these, 1 and 2 are isotypical and form a 3D supramolecular aggregation based on type-I halogen–halogen interactions (Cl···Cl or Br···Br) and have an impact on CO2 sorption properties. For the first time, halogen–halogen interactions have been used as a tool in the construction of high-dimensional CPs for sorption studies. However, analogous compounds 3 and 4 are expanded to 3D supramolecular structures based on π···π interactions. These compounds have no halogen–halogen interactions and hence become nonporous toward CO2 sorption. It appears that the halogen–halogen interactions between the 2D sheets are desirable for the uptake of CO2 gas.

Novel Br⋅⋅⋅π(Chelate) Interaction in a 1D Coordination Polymer Revealing Aromaticity

“…Besides, halogen bonding interactions, comparable to hydrogen bond, have been utilized as an important tool in the context of crystal packing of supramolecular system . Recently, we have reported the use of halogen‐halogen interactions in the construction of high‐dimensional coordination polymers for sorption studies . However, there has been no evidence of halogen⋅⋅⋅π(chelate) interactions in the domain of metal‐organic crystal engineering.…”

Cl⋅⋅⋅Cl Halogen Bonding: Nature and Effect of Substituent at Electron Donor Cl atom

“…Moreover, the halogen bonding interactions involving various electron donors like N, O, S, etc. have been studied on numerous occasions but halogen bonding involving Cl as electron donor has been studied only on few occasions . Therefore, a detailed theoretical study on the nature and other electronic properties of the Cl⋅⋅⋅Cl halogen bond is necessary to gain better understanding about this bonding This study also aims to see the effect of substitution at the electron donor Cl atom on the strength and nature of the Cl⋅⋅⋅Cl interactions.…”

On the Importance of Halogen–Halogen Interactions in the Solid State of Fullerene Halides: A Combined Theoretical and Crystallographic Study

“…Finally, we have performed a search in the CSD (Cambridge Structural Database) in order to find experimental evidence of the impact of halogen-halogen interactions on the solid state architectures of halogenated C 60 s. exponentially, due to the recognition of its importance in biological systems and the design of new materials, leading to a plethora of theoretical and experimental studies devoted to this fruitful line of research [22][23][24][25]. Apart from the classical halogen bond, there is growing interest amongst the scientific community to properly understand weaker halogen-halogen interactions [26], which have shown a promising future as stabilizing agents of metal complexes [27,28], by governing the formation of novel solid state architectures [29][30][31] and even tuning the properties of biological and conjugated materials [32][33][34][35]. In this regard, the presence of both an electron-rich "belt" and an electro-positive σ-hole (Cl, Br and I) are key to describe the two types of X···X interactions, which are usually classified as either type I and II [36].…”