The engineering of metal-organic materials with specific properties using molecular building blocks approach is possible by understanding the interplay of different interactions involved in self-assembly processes. The interest in copper complexes of 1,10-phenanthroline and its derivatives is stemming from their potential application as antimicrobial, antiviral, anti-inflammatory, antitumor agents, enzyme inhibitors, or chemical nucleases [1].The discrete coordination compounds can be extended in coordination polymers by using the exo-bidentate N,N-bipyridyl-based ligand involving pyridine rings linked by aliphatic chain, such as 1,2-bis(4-pyridyl)ethane and other similar ligands. Here, we report the crystal structures of three new Cu(II) complexes: two mononuclear [Cu(acac)(phen)Cl]CH3OH (1) and [Cu(acac)(phen)(NO3)]CH3OH (2), and 1D coordination polymer {[Cu(acac)(bpe)(NO3)]}n (3), where phen = 1,10-phenanthroline; acac = acetylacetonate and bpe = 1,2-bis(4-pyridyl)ethane (Fig.1).figureFig.1. View of mononuclear complex 2 and fragment of polymeric chain in 3 Crystals of both mononuclear compounds are triclinic, for 1: P-1, a = 8.9974(7), b = 9.2215(7), c = 12.0605(10)Å, α = 102.498(7), β = 97.666(7), γ=106.561(7)°,V=915.84(13)Å3; for 2: P-1, a = 8.6096(9), b = 10.2314(7), c = 12.1027(13)Å, α = 105.200(7), β = 104.230(9), γ = 108.009(7)°, V= 914.24(15)Å3. In the structures 1 and 2, the Cu atom adjusts the square-pyramidal coordination surrounding composed by two phen nitrogen atoms, two oxygen atoms of acac mono-anion in the basal plane and the apical position is occupied by the chloride or the nitrate anion (Fig.1, a). The molecular packing reveals the intermolecular π–π stacking interactions between the chelate phen aromatic moieties. The interplanar separation between the adjacent center symmetry related phen moieties and centroid···centroid distances between the nearest overlapping six-membered rings are 3.434Å and 3.797Å in 1, and 3.360Å and 3.701Å in 2. The addition of exo-bidentate bpe ligand in reaction which leads to complex 2 results in the one-dimensional coordination polymer 3 without phen chelate ligand. Compound 3 crystallizes in the orthorhombic space group Pbca, a=15.5250(8), b=14.5784(5), c=15.7358(7)Å, V= 3561.5(3)Å3. The copper(II) ion exhibits again a distorted square-pyramidal N2O3 geometry formed by nitrogen atoms of two bpe ligands in cis-positions, two oxygen atoms from acac chelate, and nitrate anion in apical position. The Cu···Cu separation along the polymeric zigzag chain is 13.208Å and Cu···Cu distance between the next to nearest metals equals 15.736Å.