Adsorption of Polar Volatile Organic Compounds by a Crystalline Network Structure Based on a Bis(benzimidazole)NiCl₂ Complex

Abstract

The development of efficient technologies to adsorb volatile organic compounds (VOCs) is desirable given their adverse effects on human health and the environment. Herein, we report a crystalline material formed by intermolecular hydrogen bonds among bis­(benzimidazole)­NiCl2 complexes, where bis­(benzimidazole) is phenylbis­(benzimidazol-2-yl)­methane), in conjunction with π–π stacking interactions as an adsorbent for polar VOCs such as ethers, aldehydes, ketones, carboxylic acids, esters, and chloroalkanes. The adsorbent maintains its single-crystalline state during the adsorption of the polar VOCs. A single-crystal X-ray diffraction study revealed that the intermolecular hydrogen bonds are the driving force for adsorption. We also found that the adsorption of oxygenated compounds (e.g., ethers, aldehydes, ketones, and esters) is more favorable than that of chloroalkanes such as chloroform and dichloromethane. Thus, this material can be used as an adsorbent for polar VOCs and as a separation material.

Synthesis, Structural Characterization, and Guest Exchange Properties of Hydrogen-Bonded Organic Frameworks Based on Bis(benzimidazole)ZnCl2 Complexes

“…As the incorporation of acetone or MeOH induces steric repulsion between molecules of 4 , the framework structures can be expected to change. This mechanism, induced by the cleavage of hydrogen bonds followed by the formation of alternate hydrogen bonds with organic molecules, is similar to that for VOC adsorption by the aforementioned A -based HOF (Figure b) . Previous HOF studies have mainly focused on HOFs that are assembled due to strong hydrogen bonds such as those among carboxylic acids, N-heterocycles, and charge-assisted building blocks for the purpose of being able to systematically design such frameworks; however, strategies based on strong hydrogen bonds tend to provide rigid HOFs. , Although several flexible HOFs formed by strong hydrogen bonds are known, they do not show the cleavage of intermolecular hydrogen bonds upon exposure to organic vapors .…”

“…We have recently found a flexible HOF based on a nickel dichlorido complex that bears a phenylbis­(benzimidazol-2-yl)­methane ligand ( A ; Figure a), which is assembled via intermolecular N–H···Cl hydrogen bonds . The A -based HOF adsorbs volatile organic compounds (VOCs) with hydrogen acceptor sites such as acetone, propionaldehyde (CH 3 CH 2 CHO), acetic acid (CH 3 COOH), tetrahydrofuran (THF), diethyl ether (Et 2 O), chloroform (CHCl 3 ), and dichloromethane (CH 2 Cl 2 ).…”

Competitive Adsorption of a Binary VOC Mixture from the Gas Phase onto Activated Carbon Modified with Malic Acid

“…Volatile organic compounds (VOCs) are organic compounds that are characterized by high vapor pressure values and by boiling temperature up to 250 °C (under normal conditions) . The substance considered as VOCs belongs to different groups of organic compounds, e.g., alcohols, esters, ketones, and aliphatic and aromatic hydrocarbons . Due to their properties, they evaporate easily and are slightly soluble in water.…”

“…1 The substance considered as VOCs belongs to different groups of organic compounds, e.g., alcohols, esters, ketones, and aliphatic and aromatic hydrocarbons. 2 Due to their properties, they evaporate easily and are slightly soluble in water. Volatile organic compounds are chemicals generated by many industries, such as automotive painting, petroleum refineries, solvent-based processes, plastic and rubber production, pesticide manufacturing, manufacture of electronic equipment, and pharmaceutical industry.…”

Regulation of conjugate rigid plane structures for achieving transformation of fluorescence recognition properties

“…Bisbenzimidazole ring is a simple and stable conjugate structure, which can emit fluorescence with a large Stokes shift and high fluorescence quantum yield through excited-state intermolecular proton transfer in molecules 1–4 (ESIPT). Therefore, it is an important heterocyclic motif in organic synthesis and has many potential applications in the research field, such as tunable luminescence, 5,6 anticancer properties, 7 crystal engineering, 8–10 the recovery of heavy metals from aqueous solutions 11 and volatile organic compounds 12 (VOCs). On account of this, research on metal cation ion coordination and adsorption of fluorescence probe materials has been attracting significant attention.…”