Two porous Ni-MOFs based on 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine showing solvent determined structures and distinctive sorption properties toward CO2 and alkanes

Abstract

By regulating the solvent used for synthesis, two porous Ni-MOFs, namely {[Ni₃(BTC)₂(TPT)_2/3(H₂O)_4.08(MeOH)_0.92]·2DMF·0.5H₂O·0.5MeOH}_n (1) and {[Ni₃(BTC)₂(TPT)₂(H₂O)₆]·6DMF}_n (2) (H₃BTC = 1,3,5-benzenetricarboxylic acid, TPT = 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine, DMF = N,N-dimethylformamide, and MeOH = methanol) were obtained. Compound 1 reveals a rigid 3D framework, while compound 2 shows a flexible 3-fold interpenetrated framework. Compound 1 exhibits a selective adsorption of CO₂ due to the sieving effect of the rigid framework containing two types of cages with small apertures. Noteworthily, the flexible compound 2 displays an obviously guest-induced structural transformation. The desolvated compound 2 reveals a much higher capacity toward CO₂ and n-C₄H₁₀ than those of N₂ CH₄, C₂H₆ and C₃H₈.