A hexagonal C3-symmetric (H2O)7 guest fits well into a C3-symmetric terbium complex cavity

A C3-symmetric terbium complex {[Tb2(pztc)3]⋅6.5H2O}n (1) (pztc = pyrazine-2,3,5,6-tetracarboxylate), with hexagonal cavities, has been synthesized under hydrothermal conditions and characterized by X-ray single-crystal diffraction, elemental analysis, IR, TGA, PXRD and fluorescence measurements. The layer structure of the 2D complex is just like the structure of graphite. The most appealing structure is that a hexagonal C3-symmetric (H2O)7 guest fits into the hexagonal C3-symmetric terbium complex cavity very fitly. Furthermore, when the water clusters are driven off, the framework does not collapse and the luminescence intensity increases.