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

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 pi-pi 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.