organic compounds
L-Asparagine–L-tartaric acid (1/1)
aDepartment of Physics, Madurai Kamaraj University, Madurai 625 021, India, bDepartment of Physics, The Madura College, Madurai 625 011, India, and cDepartment of Food Science and Technology, University of Ruhuna, Mapalana, Kamburupitiya (81100), Sri Lanka
*Correspondence e-mail: plakshmannilantha@ymail.com
In the title compound, C4H8N2O3·C4H6O6, the amino acid molecule exists as a zwitterion and the carboxylic acid in an un-ionized state. The tartaric acid molecules are linked into layers parallel to the ab plane by O—H⋯O hydrogen bonds. The amino acid molecules are also linked into layers parallel to the ab plane by N—H⋯O and C—H⋯O hydrogen bonds. The alternating tartaric acid and amino acid layers are linked into a three-dimensional framework by N—H⋯O and O—H⋯O hydrogen bonds.
Related literature
Our interest in the determination of the structure of the title compound is due to recent advances in organic non-linear optical (NLO) materials on account of their widespread potential industrial applications. For studies on organic non-linear optical materials, see: Cole et al. (2000); Ravi et al. (1998); Sarma et al. (1997).
Experimental
Crystal data
|
Refinement
|
Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97.
Supporting information
https://doi.org/10.1107/S1600536810030771/ci5134sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810030771/ci5134Isup2.hkl
Colourless, prismatic single crystals of (I) were grown from a
of water containing L-asparagine and tartaric acid in a 1:1 stoichiometric ratio.In the absence of significant
effects, Friedel pairs were averaged. The was assigned based on the known configuration of L-arginine and L-tartaric acid. The H atoms were placed at calculated positions [O–H = 0.82 Å, N–H = 0.86 or 0.89 Å and C–H = 0.98 Å] and were allowed to ride on their respective parent atoms with Uiso(H) = 1.2Ueq(C,N) and 1.5Ueq(O).Amino acids and
form proton-transfer complexes and hence the ionization states and stoichiometry of individual molecules and their effect on aggregation patterns are of immense interest. Our interest in the determination of the structure of the title compound is due to recent advances in organic non-linear optical (NLO) materials on account of their widespread potential industrial applications. Results have shown that an inherent relationship exists between the structure of these materials and their observed properties. On the molecular scale, the extent of charge transfer is assumed to dominate the SHG output while on the supramolecular scale, a high SHG output requires non-centrosymmetry, strong intermolecular interactions and good phase-matching ability (Sarma et al., 1997: Ravi et al., 1998: Cole et al., 2000)Fig.1 illustrates the molecular structure of the title compound, (I), and the atomic numbering scheme adopted. The amino acid molecule exists as a zwitterion, an uncommon ionization state in the crystal structures of amino-carboxylic acid complexes. Usually, a proton transfer is favoured from the carboxylic acid to the amino acid in these complexes, the former exists in the anionic state and the latter in the cationic state. Similar zwitterionic state for the amino acid molecule is observed in L-phenylalanine fumaric acid and L-phenylalanine benzoic acid. The asparagine carboxylate skeleton, which includes O2, O3, C1 and C2 is nearly planar. The deviation of the amine N atom from the plane of the carboxylate group is 0.516 (2) Å. The twist of the carboxylate group of the asparagine molecule is described by ψ1 = 160.4 (6)° and ψ2 = -24.9 (9)°, corresponding to trans and cis arrangements. The side-chain conformations are observed as χ1 = 63.9 (8)°, χ21 = -80.7 (9)° and χ22 = 95.9 (8)° for the asparagine molecule.
The tartaric acid molecule is in the unionized state. The angle between the planes of the half molecules, O9/O8/C8/C7/O7 and O4/O5/C5/C6/O6 is 57.6 (3)°, which is closer to the value of 54.6° found in the structure of tartaric acid. The carbon skeleton of the tartrate molecule is non-planar, with a C5—C6—C7—C8 torsion angle of - 168.5 (6)°.
Fig. 2 shows the partial packing diagram in which there are large number of O—H···O and N—H···O hydrogen bonds. The tartaric acid molecules are linked into layers parallel to the ab plane by O—H···O hydrogen bonds. The amino acid molecules are linked into chains propagating along the b axis by N—H···O hydrogen bonds. The chains are arranged in layers parallel to the ab plane. The alternating tartaric acid and amino acid layers are linked into a three-dimensional framework by N—H···O and O—H···O hydrogen bonds. In addition, C—H···O hydrogen bonds are observed.
Our interest in the determination of the structure of the title compound is due to recent advances in organic non-linear optical (NLO) materials on account of their widespread potential industrial applications. For studies on organic non-linear optical materials, see: Cole et al. (2000); Ravi et al. (1998); Sarma et al. (1997).
Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell
CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atom-numbering scheme. | |
Fig. 2. Part of the crystal packing of (I), viewed down the a axis. Hydrogen bonds are shown as dashed lines. |
C4H8N2O3·C4H6O6 | F(000) = 296 |
Mr = 282.21 | Dx = 1.617 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 25 reflections |
a = 5.0860 (4) Å | θ = 2.7–25° |
b = 9.6720 (6) Å | µ = 0.15 mm−1 |
c = 11.8340 (8) Å | T = 293 K |
β = 95.311 (8)° | Block, colourless |
V = 579.64 (7) Å3 | 0.28 × 0.23 × 0.21 mm |
Z = 2 |
Nonius MACH-3 diffractometer | 1015 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.095 |
Graphite monochromator | θmax = 25.0°, θmin = 2.7° |
ω–2θ scans | h = 0→6 |
Absorption correction: ψ scan (North et al., 1968) | k = −1→11 |
Tmin = 0.959, Tmax = 0.969 | l = −14→13 |
1339 measured reflections | 2 standard reflections every 60 min |
1073 independent reflections | intensity decay: none |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.053 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.226 | H-atom parameters constrained |
S = 1.38 | w = 1/[σ2(Fo2) + (0.1143P)2 + 0.7291P] where P = (Fo2 + 2Fc2)/3 |
1073 reflections | (Δ/σ)max = 0.001 |
172 parameters | Δρmax = 0.34 e Å−3 |
1 restraint | Δρmin = −0.40 e Å−3 |
C4H8N2O3·C4H6O6 | V = 579.64 (7) Å3 |
Mr = 282.21 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 5.0860 (4) Å | µ = 0.15 mm−1 |
b = 9.6720 (6) Å | T = 293 K |
c = 11.8340 (8) Å | 0.28 × 0.23 × 0.21 mm |
β = 95.311 (8)° |
Nonius MACH-3 diffractometer | 1015 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.095 |
Tmin = 0.959, Tmax = 0.969 | 2 standard reflections every 60 min |
1339 measured reflections | intensity decay: none |
1073 independent reflections |
R[F2 > 2σ(F2)] = 0.053 | 1 restraint |
wR(F2) = 0.226 | H-atom parameters constrained |
S = 1.38 | Δρmax = 0.34 e Å−3 |
1073 reflections | Δρmin = −0.40 e Å−3 |
172 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.0957 (12) | 0.4538 (7) | 0.1832 (5) | 0.0531 (18) | |
O2 | 0.7732 (11) | 0.5170 (7) | 0.5295 (5) | 0.0459 (16) | |
O3 | 0.5946 (13) | 0.3196 (8) | 0.5798 (5) | 0.0544 (18) | |
N1 | 0.0876 (12) | 0.6710 (7) | 0.2495 (5) | 0.0377 (16) | |
H1A | −0.0578 | 0.6889 | 0.2091 | 0.045* | |
H1B | 0.1622 | 0.7336 | 0.2930 | 0.045* | |
N2 | 0.2460 (11) | 0.3066 (7) | 0.4019 (5) | 0.0322 (14) | |
H2A | 0.0730 | 0.3170 | 0.3847 | 0.039* | |
H2B | 0.2741 | 0.2509 | 0.4617 | 0.039* | |
H2C | 0.3176 | 0.2698 | 0.3430 | 0.039* | |
C1 | 0.6013 (12) | 0.4214 (8) | 0.5193 (5) | 0.0280 (15) | |
C2 | 0.3687 (13) | 0.4442 (8) | 0.4293 (5) | 0.0263 (15) | |
H2 | 0.2378 | 0.5013 | 0.4633 | 0.032* | |
C3 | 0.4415 (14) | 0.5175 (8) | 0.3216 (6) | 0.0333 (17) | |
H3A | 0.5336 | 0.6030 | 0.3420 | 0.040* | |
H3B | 0.5585 | 0.4592 | 0.2822 | 0.040* | |
C4 | 0.1954 (14) | 0.5483 (8) | 0.2447 (6) | 0.0328 (16) | |
O4 | 0.2756 (10) | −0.0470 (6) | −0.0292 (4) | 0.0378 (13) | |
H4 | 0.1664 | −0.0392 | −0.0843 | 0.057* | |
O5 | 0.4110 (10) | 0.1599 (6) | −0.0849 (5) | 0.0396 (14) | |
O6 | 0.8377 (9) | 0.1558 (6) | 0.0676 (4) | 0.0355 (13) | |
H6 | 0.7635 | 0.2283 | 0.0478 | 0.053* | |
O7 | 0.3467 (9) | 0.1735 (7) | 0.1895 (4) | 0.0385 (14) | |
H7 | 0.2136 | 0.1605 | 0.1462 | 0.058* | |
O8 | 0.7364 (9) | 0.1781 (7) | 0.3463 (5) | 0.0418 (15) | |
O9 | 0.9010 (10) | −0.0231 (6) | 0.2943 (5) | 0.0378 (14) | |
H9 | 1.0049 | −0.0102 | 0.3505 | 0.057* | |
C5 | 0.4314 (12) | 0.0606 (9) | −0.0232 (5) | 0.0283 (15) | |
C6 | 0.6460 (13) | 0.0500 (8) | 0.0750 (6) | 0.0269 (15) | |
H6A | 0.7333 | −0.0400 | 0.0712 | 0.032* | |
C7 | 0.5159 (12) | 0.0584 (8) | 0.1865 (6) | 0.0296 (15) | |
H7A | 0.4173 | −0.0268 | 0.1977 | 0.035* | |
C8 | 0.7309 (12) | 0.0778 (8) | 0.2842 (5) | 0.0274 (16) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.054 (4) | 0.034 (3) | 0.061 (4) | 0.011 (3) | −0.043 (3) | −0.010 (3) |
O2 | 0.034 (3) | 0.052 (4) | 0.047 (3) | −0.006 (3) | −0.025 (2) | 0.006 (3) |
O3 | 0.052 (4) | 0.050 (4) | 0.054 (4) | −0.010 (3) | −0.032 (3) | 0.018 (3) |
N1 | 0.034 (3) | 0.037 (4) | 0.039 (3) | 0.002 (3) | −0.017 (3) | −0.002 (3) |
N2 | 0.022 (3) | 0.039 (4) | 0.033 (3) | −0.003 (3) | −0.009 (2) | −0.001 (3) |
C1 | 0.017 (3) | 0.042 (4) | 0.023 (3) | 0.003 (3) | −0.008 (2) | −0.003 (3) |
C2 | 0.023 (3) | 0.033 (4) | 0.021 (3) | 0.003 (3) | −0.008 (3) | −0.004 (3) |
C3 | 0.027 (3) | 0.041 (4) | 0.030 (3) | −0.003 (3) | −0.010 (3) | 0.005 (3) |
C4 | 0.029 (3) | 0.036 (4) | 0.031 (3) | −0.001 (3) | −0.011 (3) | 0.003 (3) |
O4 | 0.035 (3) | 0.033 (3) | 0.041 (3) | −0.005 (3) | −0.023 (2) | 0.001 (3) |
O5 | 0.034 (3) | 0.043 (3) | 0.038 (3) | −0.001 (3) | −0.012 (2) | 0.008 (3) |
O6 | 0.023 (2) | 0.041 (3) | 0.040 (3) | −0.004 (2) | −0.0068 (19) | 0.001 (3) |
O7 | 0.021 (2) | 0.054 (4) | 0.037 (3) | 0.008 (2) | −0.0123 (19) | −0.008 (3) |
O8 | 0.023 (2) | 0.056 (4) | 0.044 (3) | 0.004 (3) | −0.015 (2) | −0.019 (3) |
O9 | 0.029 (3) | 0.041 (3) | 0.039 (3) | 0.006 (2) | −0.019 (2) | 0.000 (3) |
C5 | 0.021 (3) | 0.037 (4) | 0.026 (3) | 0.006 (3) | −0.007 (2) | −0.006 (3) |
C6 | 0.019 (3) | 0.029 (3) | 0.030 (4) | 0.001 (3) | −0.008 (3) | −0.002 (3) |
C7 | 0.019 (3) | 0.036 (4) | 0.031 (3) | 0.002 (3) | −0.011 (2) | −0.001 (3) |
C8 | 0.017 (3) | 0.039 (4) | 0.025 (3) | −0.002 (3) | −0.005 (2) | 0.003 (3) |
O1—C4 | 1.247 (10) | O4—C5 | 1.306 (10) |
O2—C1 | 1.271 (10) | O4—H4 | 0.82 |
O3—C1 | 1.219 (10) | O5—C5 | 1.205 (10) |
N1—C4 | 1.311 (11) | O6—C6 | 1.422 (9) |
N1—H1A | 0.86 | O6—H6 | 0.82 |
N1—H1B | 0.86 | O7—C7 | 1.409 (9) |
N2—C2 | 1.492 (10) | O7—H7 | 0.82 |
N2—H2A | 0.89 | O8—C8 | 1.215 (9) |
N2—H2B | 0.89 | O9—C8 | 1.302 (9) |
N2—H2C | 0.89 | O9—H9 | 0.82 |
C1—C2 | 1.533 (9) | C5—C6 | 1.522 (9) |
C2—C3 | 1.533 (10) | C6—C7 | 1.532 (10) |
C2—H2 | 0.98 | C6—H6A | 0.98 |
C3—C4 | 1.507 (9) | C7—C8 | 1.528 (8) |
C3—H3A | 0.97 | C7—H7A | 0.98 |
C3—H3B | 0.97 | ||
C4—N1—H1A | 120.0 | O1—C4—C3 | 118.6 (7) |
C4—N1—H1B | 120.0 | N1—C4—C3 | 118.7 (7) |
H1A—N1—H1B | 120.0 | C5—O4—H4 | 109.5 |
C2—N2—H2A | 109.5 | C6—O6—H6 | 109.5 |
C2—N2—H2B | 109.5 | C7—O7—H7 | 109.5 |
H2A—N2—H2B | 109.5 | C8—O9—H9 | 109.5 |
C2—N2—H2C | 109.5 | O5—C5—O4 | 125.7 (6) |
H2A—N2—H2C | 109.5 | O5—C5—C6 | 122.1 (7) |
H2B—N2—H2C | 109.5 | O4—C5—C6 | 112.1 (6) |
O3—C1—O2 | 126.0 (6) | O6—C6—C5 | 110.6 (6) |
O3—C1—C2 | 117.5 (6) | O6—C6—C7 | 111.6 (6) |
O2—C1—C2 | 116.2 (7) | C5—C6—C7 | 108.5 (5) |
N2—C2—C3 | 111.1 (5) | O6—C6—H6A | 108.7 |
N2—C2—C1 | 107.6 (6) | C5—C6—H6A | 108.7 |
C3—C2—C1 | 114.5 (5) | C7—C6—H6A | 108.7 |
N2—C2—H2 | 107.8 | O7—C7—C8 | 106.3 (6) |
C3—C2—H2 | 107.8 | O7—C7—C6 | 112.2 (6) |
C1—C2—H2 | 107.8 | C8—C7—C6 | 108.8 (5) |
C4—C3—C2 | 110.0 (6) | O7—C7—H7A | 109.8 |
C4—C3—H3A | 109.7 | C8—C7—H7A | 109.8 |
C2—C3—H3A | 109.7 | C6—C7—H7A | 109.8 |
C4—C3—H3B | 109.7 | O8—C8—O9 | 124.4 (6) |
C2—C3—H3B | 109.7 | O8—C8—C7 | 122.0 (6) |
H3A—C3—H3B | 108.2 | O9—C8—C7 | 113.6 (6) |
O1—C4—N1 | 122.6 (6) | ||
O3—C1—C2—N2 | −24.9 (9) | O5—C5—C6—C7 | 111.3 (8) |
O2—C1—C2—N2 | 160.4 (6) | O4—C5—C6—C7 | −67.4 (8) |
O3—C1—C2—C3 | −149.0 (7) | O6—C6—C7—O7 | 70.9 (7) |
O2—C1—C2—C3 | 36.4 (9) | C5—C6—C7—O7 | −51.2 (8) |
N2—C2—C3—C4 | 63.9 (8) | O6—C6—C7—C8 | −46.4 (8) |
C1—C2—C3—C4 | −173.9 (6) | C5—C6—C7—C8 | −168.5 (6) |
C2—C3—C4—O1 | −80.7 (9) | O7—C7—C8—O8 | −0.7 (9) |
C2—C3—C4—N1 | 95.9 (8) | C6—C7—C8—O8 | 120.3 (7) |
O5—C5—C6—O6 | −11.4 (9) | O7—C7—C8—O9 | 178.5 (6) |
O4—C5—C6—O6 | 170.0 (6) | C6—C7—C8—O9 | −60.6 (8) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O5i | 0.86 | 2.23 | 3.053 (8) | 160 |
N1—H1B···O3ii | 0.86 | 2.04 | 2.856 (9) | 159 |
N2—H2A···O8iii | 0.89 | 2.19 | 2.895 (8) | 136 |
N2—H2B···O2iv | 0.89 | 2.28 | 2.921 (9) | 129 |
N2—H2C···O7 | 0.89 | 2.06 | 2.912 (8) | 160 |
N2—H2C···O8 | 0.89 | 2.30 | 2.916 (8) | 126 |
O4—H4···O1v | 0.82 | 1.69 | 2.500 (6) | 168 |
O6—H6···O4vi | 0.82 | 2.19 | 2.959 (8) | 156 |
O7—H7···O6iii | 0.82 | 2.05 | 2.850 (7) | 166 |
O9—H9···O2vii | 0.82 | 1.75 | 2.570 (7) | 180 |
C2—H2···O2iii | 0.98 | 2.56 | 3.426 (9) | 147 |
C3—H3A···O3ii | 0.97 | 2.40 | 3.158 (10) | 134 |
Symmetry codes: (i) −x, y+1/2, −z; (ii) −x+1, y+1/2, −z+1; (iii) x−1, y, z; (iv) −x+1, y−1/2, −z+1; (v) −x, y−1/2, −z; (vi) −x+1, y+1/2, −z; (vii) −x+2, y−1/2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C4H8N2O3·C4H6O6 |
Mr | 282.21 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 293 |
a, b, c (Å) | 5.0860 (4), 9.6720 (6), 11.8340 (8) |
β (°) | 95.311 (8) |
V (Å3) | 579.64 (7) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.15 |
Crystal size (mm) | 0.28 × 0.23 × 0.21 |
Data collection | |
Diffractometer | Nonius MACH-3 |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.959, 0.969 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1339, 1073, 1015 |
Rint | 0.095 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.053, 0.226, 1.38 |
No. of reflections | 1073 |
No. of parameters | 172 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.40 |
Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1996), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O5i | 0.86 | 2.23 | 3.053 (8) | 160 |
N1—H1B···O3ii | 0.86 | 2.04 | 2.856 (9) | 159 |
N2—H2A···O8iii | 0.89 | 2.19 | 2.895 (8) | 136 |
N2—H2B···O2iv | 0.89 | 2.28 | 2.921 (9) | 129 |
N2—H2C···O7 | 0.89 | 2.06 | 2.912 (8) | 160 |
N2—H2C···O8 | 0.89 | 2.30 | 2.916 (8) | 126 |
O4—H4···O1v | 0.82 | 1.69 | 2.500 (6) | 168 |
O6—H6···O4vi | 0.82 | 2.19 | 2.959 (8) | 156 |
O7—H7···O6iii | 0.82 | 2.05 | 2.850 (7) | 166 |
O9—H9···O2vii | 0.82 | 1.75 | 2.570 (7) | 180 |
C2—H2···O2iii | 0.98 | 2.56 | 3.426 (9) | 147 |
C3—H3A···O3ii | 0.97 | 2.40 | 3.158 (10) | 134 |
Symmetry codes: (i) −x, y+1/2, −z; (ii) −x+1, y+1/2, −z+1; (iii) x−1, y, z; (iv) −x+1, y−1/2, −z+1; (v) −x, y−1/2, −z; (vi) −x+1, y+1/2, −z; (vii) −x+2, y−1/2, −z+1. |
Acknowledgements
SN thanks the CSIR for the funding provided under the Emeritus Scientist Scheme. JS thanks the management of The Madura College, Madurai, and DST–FIST for funding.
References
Cole, J. M., Wilson, C. C., Howard, J. A. K. & Cruickshank, F. R. (2000). Acta Cryst. B56, 1085–1093. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Enraf–Nonius (1994). CAD-4 EXPRESS. Enraf–Nonius, Delft, The Netherlands. Google Scholar
Harms, K. & Wocadlo, S. (1996). XCAD4. University of Marburg, Germany. Google Scholar
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359. CrossRef IUCr Journals Web of Science Google Scholar
Ravi, M., Gangopadhyay, P., Rao, D. N., Cohen, S., Agranat, I. & Radhakrishnan, T. P. (1998). Chem. Mater. 10, 2371–2377. Web of Science CSD CrossRef Google Scholar
Sarma, J. A. R. P., Allen, F. H., Hoy, V. J., Howard, J. A. K., Thaimattam, R., Biradha, K. & Desiraju, G. R. (1997). J. Chem. Soc. Chem. Commun. pp. 101–102. CSD CrossRef Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Amino acids and carboxylic acids form proton-transfer complexes and hence the ionization states and stoichiometry of individual molecules and their effect on aggregation patterns are of immense interest. Our interest in the determination of the structure of the title compound is due to recent advances in organic non-linear optical (NLO) materials on account of their widespread potential industrial applications. Results have shown that an inherent relationship exists between the structure of these materials and their observed properties. On the molecular scale, the extent of charge transfer is assumed to dominate the SHG output while on the supramolecular scale, a high SHG output requires non-centrosymmetry, strong intermolecular interactions and good phase-matching ability (Sarma et al., 1997: Ravi et al., 1998: Cole et al., 2000)
Fig.1 illustrates the molecular structure of the title compound, (I), and the atomic numbering scheme adopted. The amino acid molecule exists as a zwitterion, an uncommon ionization state in the crystal structures of amino-carboxylic acid complexes. Usually, a proton transfer is favoured from the carboxylic acid to the amino acid in these complexes, the former exists in the anionic state and the latter in the cationic state. Similar zwitterionic state for the amino acid molecule is observed in L-phenylalanine fumaric acid and L-phenylalanine benzoic acid. The asparagine carboxylate skeleton, which includes O2, O3, C1 and C2 is nearly planar. The deviation of the amine N atom from the plane of the carboxylate group is 0.516 (2) Å. The twist of the carboxylate group of the asparagine molecule is described by ψ1 = 160.4 (6)° and ψ2 = -24.9 (9)°, corresponding to trans and cis arrangements. The side-chain conformations are observed as χ1 = 63.9 (8)°, χ21 = -80.7 (9)° and χ22 = 95.9 (8)° for the asparagine molecule.
The tartaric acid molecule is in the unionized state. The angle between the planes of the half molecules, O9/O8/C8/C7/O7 and O4/O5/C5/C6/O6 is 57.6 (3)°, which is closer to the value of 54.6° found in the structure of tartaric acid. The carbon skeleton of the tartrate molecule is non-planar, with a C5—C6—C7—C8 torsion angle of - 168.5 (6)°.
Fig. 2 shows the partial packing diagram in which there are large number of O—H···O and N—H···O hydrogen bonds. The tartaric acid molecules are linked into layers parallel to the ab plane by O—H···O hydrogen bonds. The amino acid molecules are linked into chains propagating along the b axis by N—H···O hydrogen bonds. The chains are arranged in layers parallel to the ab plane. The alternating tartaric acid and amino acid layers are linked into a three-dimensional framework by N—H···O and O—H···O hydrogen bonds. In addition, C—H···O hydrogen bonds are observed.