On the way to copper(I) iodide coordination polymers with specific luminescent properties, the in situ reduction of Cu(II) in the presence of KI and bidentate N-heteroatomic ligand, either pyrazine (pyz) or 4,4'-bipyridine (bpy), resulted in one two-dimensional and two three-dimensional new coordination networks. Starting from Cu(NO)·3HO in the presence of pyz, successive precipitation of known yellow [(CuI)(pyz)], new orange [CuI(pyz)], and new dark blue {[Cu(pyz)]·I} polymeric solids was observed. Starting from the same salt in the presence of bpy resulted in the successive precipitation of known yellow [(CuI)(bpy)] and new brown {[Cu(NO)(bpy)]·I·(dmf·HO)} coordination polymers. By using either Cu(CHCOO)·HO or Cu(BF) as starting materials, both known forms, yellow [(CuI)(bpy)] and orange [CuI(bpy)], precipitated successively. The new solids were characterized by IR spectroscopy and X-ray analysis. [CuI(pyz)] represents the missing member in the row of two-dimensional coordination networks with general formula [CuX(pyz)] (X = Cl, Br, I). Its steady state and time-resolved characterization together with DFT and TDDFT calculations revealed that the emission at room temperature is mainly delayed fluorescence originating from mixed singlet metal-to-ligand charge transfer and halide-to-ligand charge transfer states, while that at 77 K is phosphorescence, associated with the small singlet-triplet energy differences (ΔE = 70 meV).