Mixed‐Ligand Oxidovanadium(IV/V) Complexes Chelated by α‐Hydroxycarboxylate and 2‐(1H‐Imidazol‐2‐yl)pyridine: Localized Structures and Gas Adsorption

Abstract

Monomeric oxidovanadium(IV) citrate and malate, [VO-(H 2 cit)(Him-py)] • H 2 O (1) and [VO(R,S-Hmal)(Him-py)] (2), and an additive of mixed-valence oxidovanadiummalic acid, H 2 glyc = glycolic acid] have been isolated from the reactions of vanadyl sulfate with αhydroxycarboxylate (citrate, malate, and glycolate) and 2-(1Himidazol-2-yl)pyridine in acidic solutions, respectively. The citrate or malate chelates to vanadium atom tridentately through α-hydroxy, α-carboxy and β-carboxy groups that different with bidentate glycolate, while the other β-carboxy acidic group of citrate in 1 remains uncoordinated and participates in strong hydrogen bonds with water molecules. Further substitution of 2-(1H-imidazol-2-yl)pyridine for citrate in 1 results in the formation of [VO 2 (Him-py)(im-py)] 3 • 4.5H 2 O (4) in basic solution. With comparable chelation, 1 shares a similar VÀ O α-hydroxy distance [2.214( 2) Å] with that observed in FeVcofactor [2.156 av Å], [1] where a protonated model is suggested for the local chelated environment of FeV-cofactor in citratesubstituted V-nitrogenase variant. Interestingly, 2D porous structure of additive 3 features two types of irregular microchannels with diameters of 16.6 and 6.4 Å, respectively, which can adsorb CO 2 and O 2 for 9.28 and 29.68 mg/g at 29.89 bar, respectively, while little or no adsorption for H 2 , N 2 , and CH 4 .

Coordination-Driven Self-Assembly of Complexes Constructed from Two Helical Ligands: Synthesis, Structures, and Selective Gas Adsorption Properties

“…The PLATON calculations reveal the limited solvent-accessible void, which support the surface adsorption (Table S4). , The CO 2 , methanol, and ethanol vapor adsorption/desorption behavior was measured at room temperature, and the maximum quantities adsorbed by complexes 1 – 8 at P / P 0 = 0.99 are listed in Table . The CO 2 adsorption isotherms show that all of the complexes exhibit a relatively low adsorption capacity (Figure a).…”

1D Coordination Polymers Constructed from Pyridine-2,6-Dicarboxamide Ligands Showing Selective and Recyclable Adsorption toward Methanol Vapor

“…Gas (N 2 , H 2 , O 2 , CO 2 , CH 4 , ethylene, and acetylene) and alcohol vapor (methanol, ethanol, propanol, and isopropanol) adsorption was then obtained at room temperature (298 K). The experimental results showed that all the CPs exhibited no affinity for the selected nonpolar gas (N 2 , H 2 , O 2 , CH 4 , ethylene, and acetylene) during the adsorption process, which confirmed the nonporosity of the CPs, and the CPs had no surface adsorption toward the above gas at room temperature. , …”

“…The experimental results showed that all the CPs exhibited no affinity for the selected nonpolar gas (N 2 , H 2 , O 2 , CH 4 , ethylene, and acetylene) during the adsorption process, which confirmed the nonporosity of the CPs, and the CPs had no surface adsorption toward the above gas at room temperature. 63,64 The adsorption/desorption isotherms of CP 1−8 toward CO 2 , methanol, ethanol, propanol, and isopropanol vapor at room temperature are shown in Figures 10 and S17, and the quantities adsorbed of CP 1−8 at P/P 0 = 0.99 are provided in Table 2. The results showed that all of the adsorption isotherms belonged to a typical Type-III curve and exhibited remarkable desorption hysteresis.…”