Unraveling the multi-functional behavior in a series of Metal Organic Frameworks

Three new 2D/3D Metal-Organic Frameworks (MOFs), ([Zn(2,6-ndc)(aldrithiol)]·3(H₂O))_n (1), ([Co(2,6-ndc)(aldrithiol)(H₂O)₂]·2(H₂O))_n (2), ([Cd₂(2,6-ndc)₂(aldrithiol)₂(H₂O)₂]·(aldrithiol)·(EtOH)·3(H₂O))_n (3), (2,6-ndc = 2,6-naphthalene dicarboxylic acid; aldrithiol = 4,4'-dipyridyl disulphide) have been synthesized and structurally characterized. Compounds 1 and 2 have 2D layered architectures with similar framework topology whereas 3 is a 2-fold interwoven three dimensional framework. Sorption studies reveal that compounds 1-3 selectively adsorbs CO₂ over other gases and H₂O over other solvents. Proton conductivity study of compounds 1 and 2 show highest values of 6.73 x 10^-7 S.cm^-1, 1.96 x 10^-5 S.cm^-1 at 318 K and 95% RH and these values are humidity dependent. Photoluminescent properties of compounds 1 and 3 show metal perturbed (π*–π and π*-n) intra ligand charge transfer transitions. Additionally, Compound 3 also displays reversible adsorption of molecular iodine. - Graphical abstarct: Three new 2D/3D interpenetrated MOFs are synthesized and their multifunctional material properties such as adsorption, proton conduction, iodine adsorption as well as luminscence have been explored. - Highlights: • We report multifunctional material properties in a series MOFs (Compounds 1-3) • All the compounds show selective adsorption of CO₂ over other gases and H₂O over other solvents. • The proton conduction property studies of all the compounds reveal the humidity dependent conductivity. • Compound 2 shows reversible adsorption of molecular iodine in the framework. • Photoluminescent properties of compounds 1 and 2 show metal perturbed intra ligand charge transfer transitions