Aqua(1,10-phenanthroline-κ2 N,N′)(dl-threoninato-κ2 N,O 1)copper(II) chloride dihydrate

The asymmetric unit of the title compound, [Cu(C4H8NO3)(C12H8N2)(H2O)]Cl·2H2O, contains a complex cation, a chloride anion and two water molecules. The CuII ion has a distorted square-pyramidal coordination geometry formed by one bidentate phenanthroline ligand, one O,N-bidentate dl-threoninate ligand and one apical water molecule. In the crystal structure, intermolecular O—H⋯O, N—H⋯O, N—H⋯Cl and O—H⋯Cl hydrogen bonds link the components into layers. A single weak intermolecular C—H⋯O interaction connects these layers into a three-dimensional network.

The asymmetric unit of the title compound, [Cu(C 4 H 8 NO 3 )-(C 12 H 8 N 2 )(H 2 O)]ClÁ2H 2 O, contains a complex cation, a chloride anion and two water molecules. The Cu II ion has a distorted square-pyramidal coordination geometry formed by one bidentate phenanthroline ligand, one O,N-bidentate dlthreoninate ligand and one apical water molecule. In the crystal structure, intermolecular O-HÁ Á ÁO, N-HÁ Á ÁO, N-HÁ Á ÁCl and O-HÁ Á ÁCl hydrogen bonds link the components into layers. A single weak intermolecular C-HÁ Á ÁO interaction connects these layers into a three-dimensional network.

Comment
The interaction of transition metal complexes with DNA is a vibrant area of research and has long been investigated in relation to the development of new reagents for molecular biology, biotechnology and medicine (Vaidyanathan et al., 2003;Rao et al., 2008;Kumar et al., 2007). Among all the transition metals, copper is the most widely used metals in these studies as it is a bioessential element with +1 and +2 oxidation states (Patel et al., 2006;Wang et al., 2007;Vaidyanathan et al., 2003). Copper(II) complexes have been found to be useful in the treatment of many diseases as well as cancer.
Copper(II) complexes of 1,10-phenanthroline and its derivatives exhibit various biological activities such as antimicrobial, antimycobaterial, anticandida and antitumor activities. Copper complexes of amino acids have been reported to exhibit effective antitumor and artificial nuclease activity. Several reports have also shown that these complexes show efficient DNA cleavage activity by either oxidative or hydrolytic pathways (Kumar et al., 2007;Zhang et al., 2004;Rao et al., 2007).
The asymmetric unit of the title compound ( Fig. 1) consists of one Cu II complex cation, one chlorine anion and two water molecules. The Cu II ion is coordinated by N1 and N2 atoms from the phenanthroline ligand and N3 and O1 atoms from the threoninato ligand in the basal plane and the O1W water molecule is coordinated in the apical site to form a distorted square-pyramidal geometry. The bond lengths are within normal values (Allen et al., 1987) and are comparable to those observed for a closely related structure (Lu et al., 2004).

Experimental
To an ethanolic solution (10.0 ml) of copper(II) chloride dihydrate (0.1708 g, 1 mmol), an ethanolic solution (10.0 ml) of DL-threonine (0.1191 g, 1 mmol) was added. After a few minutes, an ethanolic solution (20.0 ml) of 1,10-phenanthroline (0.1982 g, 1 mmol) was added dropwise to the mixture solution. The pH of the resulting solution was then adjusted to pH 8 by adding a few drops of NaOH aqueous solution. The blue solution was filtered and left to evaporate slowly at room temperature. Blue blocky single crystals of the title compound suitable for X-ray diffraction were obtained after a few days.

Refinement
H atoms attached to N and O atoms were located from difference Fourier map and allowed to ride on their parent atoms and constrained to be 1.5U eq for the water molecules and 1.2U eq for the amino group. The remaining H atoms were positioned supplementary materials sup-2 geometrically and refined using a riding model, with U iso (H) = 1.2 or 1.5 U eq (C

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.