Subtle structural variation in copper metal-organic frameworks: syntheses, structures, magnetic properties and catalytic behaviour.

Two new copper metal-organic frameworks containing 5-nitro-1,3-benzenedicarboxylate (5-nbdc) have been prepared from the reaction between Cu(NO(3))(2).3H(2)O and H(2)(5-nbdc) in DMF at different temperatures. Single crystal X-ray structures of {[Cu(2)(5-nbdc)(2)(DMF)(2)].2DMF}(infinity) () and {[Cu(2)(5-nbdc)(2)(DMF)(2)].3(1/3)DMF}(infinity) () revealed similar sheet structures, containing triangular and hexagonal pores, but differences in the stacking of the sheets. Magnetic measurements on and are consistent with antiferromagnetic dimers containing a small quantity of paramagnetic impurity. The desolvated forms of and were applied as Lewis acid catalysts in the acetylation of methyl 4-hydroxybenzoate. When the reaction between Cu(NO(3))(2).3H(2)O and H(2)(5-nbdc) was carried out in a mixture of DMF and water, the reaction gave metallomacrocycles of formula [Cu(6)(5-nbdc)(6)(H(2)O)(12)(DMF)(6)] (). These assemble through hydrogen-bonding interactions to form a gross structure in which the macrocycle pores align into channels. The reaction between Cu(NO(3))(2).3H(2)O and 5-methylsulfanylmethyl-1,3-benzenedicarboxylic acid, H(2)(5-msbdc), in DMF-water gave {[Cu(2)(5-msbdc)(2)(OH(2))(2)].3DMF}(infinity) (), which contains similar sheets to those in and , whereas the reaction with 5-amino-1,3-benzenedicarboxylic acid, H(2)(5-abdc), gave {[Cu(2)(5-abdc)(2)(DMF)(2)]}(infinity) (), which has a previously reported network based on sheets containing rhombohedral pores. The reaction between Cu(NO(3))(2).3H(2)O and 2-methoxy-1,3-benzenedicarboxylic acid, H(2)(2-mbdc), in DMF gave [Cu(2)(2-mbdc)(2)(DMF)(2)] (). The presence of the substituent in the 2-position removes the co-planarity of the carboxylate groups, and the sheet structure adopted by contains rhomboidal pores.