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(NO₃)₂·3H₂O in the presence of pyz, successive precipitation of known yellow [(Cu^II)₂(pyz)]_n, new orange [Cu^II(pyz)]_n, and new dark blue {[Cu^I(pyz)₂]·I₅}_n polymeric solids was observed. Starting from the same salt in the presence of bpy resulted in the successive precipitation of known yellow [(Cu^II)₂(bpy)]_n and new brown {[Cu^II(NO₃)(bpy)₂]·I₃·(dmf·H₂O)}_n coordination polymers. By using either Cu(CH₃COO)₂·H₂O or Cu(BF₄)₂ as starting materials, both known forms, yellow [(Cu^II)₂(bpy)]_n and orange [Cu^II(bpy)]_n, precipitated successively. The new solids were characterized by IR spectroscopy and X-ray analysis. [Cu^II(pyz)]_n represents the missing member in the row of two-dimensional coordination networks with general formula [Cu^IX(pyz)]_n (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).