Crystalline Metal Sulfonate Frameworks

With L13, in MeCN, the network [Ag(L13)(MeCN)o.5], 17a, was formed.This compound showed the expected linear coordination of silver ions by the pyridyl moieties. The remaining silver ion interacted with the sulfonate groups to form 24-membered rings (Fig. 17). 

The crystal structure of the dense phase, compound 17b, which had trigonal symmetry, showed a three-dimensional (3D) solid containing ID ribbons of silver ions (Fig. 18). Knowledge of this structure allowed an 

FIGURE 18. Three-dimensional structure of the dense phase, [Ag(L13)], 17b. The parallel ribbons of Ag ions permeating the structure are shown in black lines. 

The mechanism of interconversion of the open and dense forms of 17 (Fig. 19) can be viewed akin to the folding of a cardboard box, where the pyridyl-ligated Ag units form the top and the sulfonate ligated silver ions form the sides. The network would respond to removal of the guest MeCN molecules by filling the void by swinging one side of the box (AgSOs unit) into the void. 

FIGURE 19. Representation of the mechanism of conversion between solvated [Ag(Ll 3)(MeCN)], 17a(shown at left with MeCN molecules removed from the lower channel) and the dense phase [Ag(L13)], 17b. The three crystallographic types of Ag ions, which exist in a 2 1 1 ratio in 17b, are depicted as light, medium, and dark shades, respectively. 

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