The cyanide ligand can act as a strong sigma-donor and an effective pi-electron acceptor that exhibits versatile bridging abilities, such as terminal, mu(2)-C:N, mu(3)-C:C:N and mu(4)-C:C:N:N modes. These ligands play a key role in the formation of various copper(I) cyanide systems, including one-dimensional (1D) chains, two-dimensional (2D) layers and three-dimensional (3D) frameworks. According to the literature, numerous coordination polymers based on terminal, mu(2)-C:N and mu(3)-C,C,N bridging modes have been documented so far. However, systems based on the mu(4)-C:C:N:N bridging mode are relatively rare. In this work, a novel cyanide-bridged 3D Cu-I coordination framework, namely poly[(mu(2)-2,2'-biimidazole-kappa N-2(3):N-3')(mu(4)-cyanido-kappa C-4:C:N:N)(mu(2)-cyanido-kappa C-2:N) dicopper(I)], [Cu-2(CN)(2)(C6H6N4)](n), (I), was synthesized hydrothermally by reaction of environmentally friendly K-3[Fe(CN)(6)], CuCl2 center dot 2H(2)O and 2,2'-biimidazole (H(2)biim). It should be noted that cyanide ligands may act as reducing agents to reduce Cu-II to Cu-I under hydrothermal conditions. Compound (I) contains diverse types of bridging ligands, such as mu(4)-C:C:N:N-cyanide, mu(2)-C:N-cyanide and mu(2)-biimidazole. Interestingly, the [Cu-2] dimers are bridged by rare mu(4)-C:C:N:N-mode cyanide ligands giving rise to the first example of a 1D dimeric {[Cu-2(mu(4)-C:C:N:N)](n+)}(n) infinite chain. Furthermore, adjacent dimer-based chains are linked by mu(2)-C:N bridging cyanide ligands, generating a neutral 2D wave-like (4,4) layer structure. Finally, the 2D layers are joined together via bidentate bridging H(2)biim to create a 3D cuprous cyanide network. This arrangement leads to a systematic variation in dimensionality from 1D chain -> 2D sheet -> 3D framework by different types of bridging ligands. Compound (I) was further characterized by thermal analysis, solid-state UV-Vis diffuse-reflectance and photoluminescence studies. The solid-state UV-Vis diffuse-reflectance spectra show that compound (I) is a wide-gap semiconductor with band gaps of 3.18 eV. The photoluminescence study shows a strong blue-green photoluminescence at room temperature, which may be associated with metal-to-ligand charge transfer.