Metal–Organic Frameworks Based on Flexible
V-Shaped Polycarboxylate Acids: Hydrogen Bondings, Non-Interpenetrated
and Polycatenated
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Abstract
Solvothermal reactions of 4,4′-dicarboxydiphenylamine
(H<sub>2</sub>L) with 4,4′-bis(imidazol-1-yl)phenyl (BIP) and
4,4′-bis(imidazol-1-yl)diphenyl
(BIBP) in the presence of cobalt(II), cadmium(II), zinc(II) salts
in H<sub>2</sub>O/CH<sub>3</sub>CN or H<sub>2</sub>O/DMF produced
five new complexes, namely, [Co<sub>2</sub>(L)<sub>2</sub>(BIP)<sub>2</sub>·3H<sub>2</sub>O]<sub><i>n</i></sub> (<b>1</b>), [Co(L)(BIP)·2CH<sub>3</sub>CN]<sub><i>n</i></sub> (<b>2</b>), [Co(L)(BIBP)·H<sub>2</sub>O]<sub><i>n</i></sub> (<b>3</b>), [Cd(L)(BIBP)]<sub><i>n</i></sub> (<b>4</b>), [Zn(L)(BIBP)]<sub><i>n</i></sub> (<b>5</b>). Compound <b>1</b> has binuclear Co(II) clusters,
which are linked by L<sup>2–</sup> and BIP to generate a rare
three-dimensional (3D) non-interpenetrated <b>cds</b>-type framework,
and displays ferromagnetic character. Compound <b>2</b> possesses
unusual 3-fold 2D → 2D polycatenation of (4, 4) nets. Compound <b>3</b> reveals a (4, 4) grid topology with very strong hydrogen
bondings due to the abundant uncoordinated carboxyl groups, which
load in the structure like a freely dangling arm. Compound <b>3</b> also displays weak ferromagnetic character. Compounds <b>4</b> and <b>5</b> are isomorphic. H<sub>2</sub>L and BIBP ligands
in <b>4</b> and <b>5</b> interact with a metal center
to form wave-like 2D sheets. In addition, the thermal stabilities
and photochemical properties of compounds have been studied
