Glycine–d-tartaric acid (1/1)

In the title co-crystal, C2H5NO2·C4H6O6, the gylcine molecule is present in the zwitterion form. In the tartaric acid molecule there is a short intramolecular O—H⋯O contact. In the crystal, the tartaric acid molecules are linked via pairs of O—H⋯O hydrogen bonds, forming inversion dimers. These dimers are linked via a number of O—H⋯O and N—H⋯O hydrogen bonds involving the two components, forming a three-dimensional network.

In the title co-crystal, C 2 H 5 NO 2 ÁC 4 H 6 O 6 , the gylcine molecule is present in the zwitterion form. In the tartaric acid molecule there is a short intramolecular O-HÁ Á ÁO contact. In the crystal, the tartaric acid molecules are linked via pairs of O-HÁ Á ÁO hydrogen bonds, forming inversion dimers. These dimers are linked via a number of O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds involving the two components, forming a three-dimensional network.
Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT-NT (Bruker, 2004); data reduction: SAINT-NT and XPREP (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-32 (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009  Glycine is the simplest aminoacid that is not optically active. It is essential for biosynthesis of nucleic acids as well as the biosynthesis of bile acids, creatine phosphate and other amino acids. Its geometric features of non covalent interactions at atomic resolution are important in the structural assembly and functions of proteins. In the title compound(I), glycine is in the zwitterionic form. The tartaric acid molecule is in the un-ionized state. The angle between the planes of the half molecules O1/O2/C1/C2/O3 and O5/O6/C4/C3/O4 is 62.74 (3)°, which is closer to the value of 54.6° found in the structure of tartaric acid.
The molecular structure of (I) is shown in the ( Fig.1) and selected geometric parameters listed in Table 1. The bond lengths for C=N, C=O, C-C are within normal ranges (Allen 2002). The dihedral angle between planes of D-tartaric acid and glycine is 51.14 (9)°. The molecules related by the 2 1 screw along b axis are linked by intermolecular O-H···O hydrogen bond generating a supramolecular chain.
The carbon skeleton of tartaric molecule is non-planar with a C1-C2-C3-C4 torsion angle of 177.8 (1)°. Fig.2 shows the packing diagram in which there are a large number of N-H···O and O-H···O hydrogen bonds.

Experimental
Colourless single crystals were grown as transparent needles by slow evaporation method from a saturated aqueous solution containing glycine and D-tartaric acid in a 1:1 stoichiometric ratio.

Refinement
All the hydrogen atoms were geometrically fixed and allowed to ride on their parent atoms with C-H = 0.97and 0.98 Å, and U iso = 1.2 eq (C). Hydrogen atoms attached to O and N were refined isotropically.

Computing details
Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT-NT (Bruker, 2004); data reduction: SAINT-NT and XPREP (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-32 (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009   The molecular structure and labelling scheme for (I) with displacement ellipsoid of non-H atoms are drawn at the 30% probability level.    where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.49 e Å −3 Δρ min = −0.22 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.074 (5) 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 > 2sigma(F 2 ) is used only for calculating R-factors(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.