Assembly of Two Metal–Organic Frameworks Based on Distinct Cobalt Dimeric Building Blocks Induced by Ligand Modification: Gas Adsorption and Magnetic Properties

Abstract

Solvothermal reaction of 3,5-di(pyridin-4-yl) benzoic acid (HDPB) with Co(II) leads to a novel metal-organic framework, [CoO(DPB)(DMF)]· xS (1), which represents a rare reo-type net with trigonal prismatic cobalt dimer, [CoO(CO)N], as building blocks to construct a 3D framework containing three different types of nanoscale ML and ML polyhedron cages. More interestingly, under the same condition, the assembly of 4-methyl-3,5-di(pyridin-4-yl) benzoic acid (HMDPB) with Co(II) facilitates the formation of a cationic framework, [Co(MDPB)(DMF)](NO)· xS (2), with cobalt dimer, [Co(CO)N], as building blocks. Complex 2 represents the first example of a zeolite-like network with 48-nuclear SOD cage. The significant effect of subtle modification of ligand on the overall MOFs is discussed. Moreover, the gas adsorption studies reveal that 1 exhibits permanent porosity and selective CO uptake. Variable-temperature magnetic susceptibility measurements show that both 1 and 2 exhibit antiferromagnetic behavior.

Insight into the Construction of (3,6)-Connected rtl, ant, and Chiral anh Nets Based on Structural Investigation of Several MOFs via Steric Tuning of Linkers

“…However, in 6 , the two Co­(II) centers are connected through one μ-Cl and two μ 1,3 -carboxylate bridges with a Co–Cl–Co angle of 101.8° and a Co–Co distance of 3.6713 Å. Thus, the diverse magnetic behavior of the two MOFs may be related to different bridging fashions as well as Co–Co distances within dinuclear cobalt clusters. , …”

“…The reagents used were obtained commercially. Three ligands were prepared according to our previous work . Infrared spectra were obtained in KBr pellets on a VECTOR TM 22 spectrometer.…”

“…Various rotamers with tunable symmetries and conformation can be generated through the systematically tuned steric hindrance of substituents and further utilized to explore unique structures and unprecedented topologies. Also, in our previous work, on the basis of the tritopic pyridine-carboxylate ligand 3,5-bis­(pyridin-4-yl)­benzoic acid and its methyl-functionalized derivative 4-methyl-3,5-bis­(pyridin-4-yl)­benzoic acid with Co­(II) under the same conditions, we have delicately assembled two diverse frameworks, one consisting of three types of nanoscale cages with reo topology, and the other containing a 48-nuclear SOD cage with sod topology . The two diverse structures are significantly related to the incorporated substituents, which exert a subtle effect on the overall networks.…”

“…Herein, as a continuation of our effort in assembling MOFs based on multidentate ligands for multifunctional application, , we used the tritopic pyridine-carboxylate ligand 3,5-bis­(pyridin-4-yl)­benzoic acid (L-H) and its two functionalized derivatives 4-methyl-3,5-bis­(pyridin-4-yl)­benzoic acid (L-CH 3 ) and 4-methoxy-3,5-bis­(pyridin-4-yl)­benzoic acid (L-OCH 3 ) to assemble a series of Co-MOFs under solvothermal conditions (Scheme ). Interestingly, these six (3,6)-connected MOFs exhibit diverse topologies, which are rtl for 1 and 2 , ant for 3 and 4 , and chiral anh for 5 and 6 .…”

Viologen-Based Cationic Metal–Organic Framework for Efficient Cr2O72– Adsorption and Dye Separation

“…As a promising class of porous materials, metal–organic frameworks (MOFs) have caught considerable attention because of their tunability and diversity in structures and properties during the past decades. − High surface areas and tailorable pores of MOF materials endow them with many appealing applications, such as gas storage and separation, − catalysis, − in magnets, − luminescence and sensing, − and so forth. As a subclass of MOFs, cationic metal–organic frameworks (CMOFs), which possess positive networks, are advantageous in several particular applications including but not limited to colorimetric sensing, ion chromatography, water purification, and anionic pollutant removal. − Compared with neutral MOFs, CMOFs are rarely reported due to the formidable complexity and challenge for their syntheses.…”