Syntheses, characterization, and slow magnetic relaxation or luminescence properties of three new 2D coordination polymers

Abstract Three new 2D coordination polymers (CPs), namely, {[CoL0.5(4,4′-bbib)]}n (1), {[ZnL0.5(4,4′-bbib)]·3DMF·3H2O}n (2) and {[CdL0.5(4,4′-bbib)]·4H2O}n (3), have successfully been constructed by solvothermal method based on H4L, 4,4′-bbib and M(NO3)2 {M = Co (1), Zn (2), Cd (3); H4L = 5,5’-(1,3,6,8-tetraoxobenzo[lmn] [3,8]phenanthrolin-2,7-diyl)bis-1,3-benzenedicarboxylic acid; 4,4′-bbib = 4,4′-bis(benzoimidazo-1-yl)biphenyl}, and studied by structural analysis, magnetic properties and luminescence properties. The structural analysis shows that CPs 1-3 are 4-c 2D network structures with the point symbol of {32.62.72}, which are further expanded into 3D supramolecular architectures by the π … π and hydrogen bonding (O–H⋯O) interactions between the adjacent 2D layers. Magnetic properties show 1 presents a single-molecule magnet (SMM) and slow magnetic relaxation behavior with the energy barrier (Ueff) of 49.73 K and a pre-exponential factor (τ0) of 1.84 × 10−10 s. Luminescent experiments revealed that 2 and 3 can serve as sensors towards Fe3+ and nitroaromatic compounds (NACs) in aqueous medium with high sensitivity and selectivity.