A unique tetranuclear Cu-II-based 2D aggregate containing 26-membered Cu(II)ade macrocycles, [Cu-4(DMF)(6)(mu(4)-ade)(2)(mu(2)-Cl)(2)Cl-4](n) (1; Hade = adenine, DMF = N,N-dimethylformamide), was isolated by the reaction of CuCl2 and Hade in a mixed DMF-methanol medium and structurally characterized by X-ray crystallography, elemental analysis, Fourier transform infrared, fluorescence spectroscopy, and thermogravimetry-differential thermal analysis techniques. Unexpectedly, the adeninate in 1 represents an unprecedented tetradentate mu(4)-N1,N3,N7,N9-bridging mode, which significantly contributes to both the aggregate of four Cull cores within the subunit and the extension of the 2D covalent framework. Additionally, I displays the intense Hade-based fluorescence emission in solution at room temperature.