摘要
A series of new magnesium coordination polymers, [Mg 2 (BTEC) (H 2 O) 4 ]·2H 2 O (1), [Mg 2 (BTEC)(H 2 O) 6 ] (2), and [Mg 2 (BTEC) (H 2 O) 8 ] (3) (BTEC = 1,2,4,5-benzenetetracarboxylate anion), were synthesized from magnesium nitrate and 1,2,4,5- benzenetetracarboxylic acid with variable ratios of organic base under microwave-assisted solvothermal reactions at the temperature of 180 (1) or 150°C (2 and 3). The results from crystal structure analysis showed that 1 was a 3D metal-organic framework, 2 a 2D layer, and 3 a 1D ladder structure. In addition, heating 1 at the temperature of 150°C would convert it to 1a which can be a novel single-crystal-to-single-crystal transformation of coordination polymer. Single crystal of 1a has a new 3D structure with formula [Mg 15 (BTEC) 6 (HBTEC) 2 (H 2 O) 12 ]·4H 2 O, containing unsaturated magnesium sites. Further gas adsorption experiments revealed that 1a undergoes a highly selective sorption of hydrogen instead of nitrogen gases. Photoluminescence studies also displayed that 1a emits extra strong green luminescence around 510 nm under the excitation of ultraviolet light. © 2009 The Royal Society of Chemistry.