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A heteroporous metal–organic framework, [Cd2(2,2′-DSB)2(INH)2(H2O)2]n(1), is fabricated by the reaction of CdI2, 2-mercaptobenzoic acid (2-MBAH), and isoniazid (INH). The X-ray structure of the compound 1shows the bridging INH and 2,2′-disulfanediyldibenzoic acid (H22,2′-DSBA) around the Cd(II) ion center. 2-MBAH has been in situdimerized to the formation of 2,2′-DSB2–(S–S-bonded dianion), which has further extended to form the 2D network. However, supramolecular assembly via π···π and hydrogen bonds strengthens the structural motif within the 3D array. Optical stimulation generated the thiol radical under an argon environment followed by the electron paramagnetic resonance (EPR) study, but upon exposure to air, the EPR signal gradually disappeared by the formation of the S–S bond, which was commonly known as a self-healing property. Again, compound 1exhibited as a semiconducting material with a band gap of 3.7 eV. The I–Vcharacteristics of 1show that the conductivity is intensified by an optical response. The Schottky diode property of 1shows a lower barrier height, a lower resistance, and a higher conductivity upon illumination at 360 nm.

Syntheses, structural characterizations, photoluminescence, and adsorption properties of three new azo-functionalized Cd(II)-MOFs, namely, {[Cd(azbpy)(msuc)]·2.5(H2O)}n(2), {[Cd(azbpy)(mglu)]·5(H2O)}n(3), and {[Cd1.5(azbpy)2(glu)]·(NO3)·MeOH}n(4) [where msuc2−= methylsuccinate; mglut2−= methylglutarate; glut2−= glutarate; azbpy = 4,4′-azobispyridine] have been reported. The compounds show different structures only with the variation of aliphatic dicarboxylates. The photoswitching behavior for the above-mentioned newly synthesized Cd(II)-MOFs along with one of our previously reported other azo-functionalized Cd(II)-MOF, namely, {[Cd(azbpy)(suc)]·2(H2O)}n(1), has been studied extensively. At photoilluminated condition, the conductivity values can draw a clear structure–property relationship among the structures of compounds 1–4. Single crystal structural analysis reveals that all the compounds exhibit a three-dimensional (3D) framework connected by azbpy linker and respective aliphatic dicarboxylate through their bis-chelating mono/bis oxo-bridging fashion. Compounds 1–3exhibit an iso-structural honeycomb like 3D framework showing the same coordination environments, where the metal-carboxylate 2D sheets of compounds 1–3are pillared by N,N′-donor azbpy linkers. On the other hand, compound 4exhibits a 2-fold interpenetrated 3D framework with a little difference in its coordination environment and the pillaring of 1D metal-carboxylate ladder by azbpy linkers. All the compounds significantly demonstrate their enhanced sensitivity under light rather than the dark condition. The gas and solvent vapor sorption studies have been performed for the synthesized compounds 2–4. Moreover, compound 2exhibits an enhanced type IV selective CO2adsorption isotherm over N2along with the appearance of gate opening phenomena in that.