A Microporous Co(II)-Based 3-D Metal Organic Framework Built from Magnetic Infinite Rod-Shaped Secondary Building Units

Abstract

The synthesis and characterization of {[Co5(INA)3(HCOO)7(DMF)(H2O)]·2DMF·4H2O}∞ (INA? = the anion of isonicotinic acid) denoted as Co5-INA·2DMF·4H2O is reported. The compound was isolated from the reaction of Co(NO3)2·6H2O with HINA in the presence of HCOOH in N,N-dimethylformamide (DMF) at 100 °C. It exhibits a rigid 3-D porous structure based on Co5 repeating units which are linked through carboxylate ligands (from HCOO? and INA?) to form an infinite rod-shaped secondary building unit (SBU). The rods are connected through isonicotinate ligands to produce a unique (3,3,4,4,4-coordinated) 5-nodal 3D network with point symbol (4.5.6.72.9)(4.5.62.7.8)(4.5.7)2(5.62.73). Gas sorption studies revealed that Co5-INA displays a microporous structure with BET area 264.5 m2?g?1 and CO2 uptake of 1.96/1.29 mmol·g?1 at 273/298 K (1 bar), respectively. Magnetism studies revealed that Co5-INA displays spin canting behavior with a spin glass relaxation process at ca. 5.0 K.