3D semiconducting Co–MOFs based on 5‐(hydroxymethyl)isophthalic acid and imidazole derivatives: syntheses and crystal structures

Two three‐dimensional cobalt‐based metal–organic frameworks with 5‐(hydroxymethyl)isophthalic acid (H 2 HIPA), namely poly[[μ 2 ‐1,4‐bis(2‐methyl‐1 H ‐imidazol‐1‐yl)benzene‐κ 2 N 3 : N 3′ ][μ 2 ‐5‐(hydroxymethyl)isophthalato‐κ 2 O 1 : O 3 ]cobalt(II)], [Co(C 9 H 6 O 5 )(C 14 H 14 N 4 )] n ( 1 ), and poly[tris[μ 2 ‐1,4‐bis(1 H ‐imidazol‐1‐yl)benzene‐κ 2 N 3 : N 3′ ]bis[μ 3 ‐5‐(hydroxymethyl)isophthalato‐κ 2 O 1 : O 3 : O 5 ]dicobalt(II)], [Co 2 (C 9 H 6 O 5 ) 2 (C 12 H 10 N 4 ) 3 ] n ( 2 ), were synthesized under similar hydrothermal conditions. Single‐crystal X‐ray diffraction analyses revealed that 5‐(hydroxymethyl)isophthalate (HIPA 2− ) and 1,4‐bis(2‐methyl‐1 H ‐imidazol‐1‐yl)benzene (1,4‐BMIB) are simple linkers connecting cobalt centres to build a fourfold interpenetration dia framework in complex 1 . However, complex 2 is a pillared‐layer framework with a (3,6)‐connected network constructed by 1,4‐bis(1 H ‐imidazol‐1‐yl)benzene (1,4‐DIB) linkers, 3‐connected HIPA 2− ligands and 6‐connected Co II centres. The above significant structural differences can be ascribed to the introduction of the different auxiliary N ‐donor ligands. Moreover, UV–Vis spectroscopy and Mott–Schottky measurements confirmed that complexes 1 and 2 are typical n‐type semiconductors.