organic compounds
Glycine–phthalic acid (1/1)
aSchool of Physics, Bharathidasan University, Tiruchirappalli 620 024, India, bDepartment of Physics and Nanotechnology, SRM University, Kattankulathur 603 203, India, and cDepartment of Bioinformatics, School of Chemical and Biotechnology, SASTRA University, Thanjavur 613 401, India
*Correspondence e-mail: thamu@scbt.sastra.edu
In the title compound, C2H5NO2·C8H6O4, the glycine molecule exists as a zwitterion (2-azaniumylethanoate) with a positively charged amino group and a negatively charged carboxylate group. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the components into layers parallel to the ab plane. The central part of each layer is composed of hydrogen-bonded glycine while phthalic acid molecules interact with the in such a way that benzene rings protrude up and down from the layer.
Related literature
For related structures, see: Losev et al. (2011); Herbstein et al. (1981). For graph-set motifs, see: Bernstein et al. (1995). For head-to-tail hydrogen bonds, see: Sharma et al. (2006); Selvaraj et al. (2007).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: EXPOSE in IPDS-I Software (Stoe & Cie, 2000); cell CELL in IPDS-I Software; data reduction: INTEGRATE in IPDS-I Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97.
Supporting information
https://doi.org/10.1107/S160053681204977X/cv5360sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681204977X/cv5360Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S160053681204977X/cv5360Isup3.cml
The title complex was prepared by dissolving glycine and phthalic acid in a stoichiometric ratio in double distilled water. The resulting solution was heated to ca 50° C and the title cocrystal was obtained by a slow cooling method from an aqueous solution.
The H-atoms bound to nitrogen and oxygen were located from difference electron density maps and isotropically refined. All the remaining H atoms were placed in geometrically idealized positions (C—H = 0.95-0.99 Å) and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C).
As part of our studies on amino acids and
interactions (Sharma et al. 2006; Selvaraj et al., 2007), we report here the of the title cocrystal of glycine and phthalic acid, (I).The
of (I) contains one glycine molecule and one phthalic acid molecule (Fig. 1). The glycine molecule exists as a zwitterion with a positively charged amino group and a negatively charged carboxylate group as found in glycine-trimesic acid complex (Herbstein et al., 1981) and glycine-glutaric acid cocrystal (Losev et al., 2011), where glutaric acid exists as a neutral molecule. The phthalic acid exists as a neutral molecule with both carboxylic acid groups being unionized. The stoichiometry between the glycine and phthalic acid is 1:1.The crystal packing is stabilized by a network of N—H···O and O—H···O hydrogen bonds (Table 1). As illustrated in Fig. 2, the basic aggregation pattern observed in the complex is a layered architecture of zwitterionic glycine and neutral phthalic acid molecules. An antiparallel linear array of zwitterionic glycines are sandwiched between phthalic acid layers.
In (I), the zwitterionic glycine has one donor atom capable of forming three hydrogen bonds, and one of them forms bifurcated hydrogen bonds, while neutral phthalic acid can also forms three hydrogen bonds through two acceptors (Table 1). In the
the zwitterionic glycines are arranged in linear arrays along [010] direction. In each array, adjacent glycines are connected by a N1···O2 hydrogen bond which can be described as a head-to-tail sequence having a graph-set motif of C5 (Bernstein et al., 1995) (Fig. 3). In contrast to (I), no head-to-tail sequence was observed in glycine-glutaric acid cocrystal (Losev et al., 2011). As observed in many binary complexes of amino acids complexed with the neutral molecules in the complex do not interact among themselves. However, here, phthalic acid molecule is interconnected by zwitterionic glycines via two intermolecular N1···O3 hydrogen bonds. The glycine amino group acts as donor for 1-substituted carboxylic O3 atoms of the phthalic acid molecules emanating from different phthalic acids layers. Another carboxylic O5 atom acts as acceptor for an intermolecular hydrogen bond with the amino group of a glycine. The 2-substituted carboxylic group of the phthalic acid molecules in two different layers are interconnected by glycines. One carboxylic group in one layer interacts with the glycine in one layer, while its symmetry-related equivalents in the adjacent layers interacts with the glycine in the neighbouring layer [C12(4) graph-set motif]. The donor atoms (O4 and O6) of the phthalic acid molecule participate in intermolecular short and linear O—H···O hydrogen bonds with the carboxylate group of glycine. These hydrogen bonds produce C22(11) chains that run parallel to the a axis.For related structures, see: Losev et al. (2011); Herbstein et al. (1981). For graph-set motifs, see: Bernstein et al. (1995). For head-to-tail hydrogen bonds, see: Sharma et al. (2006); Selvaraj et al. (2007).
Data collection: EXPOSE in IPDS-I Software (Stoe & Cie, 2000); cell
CELL in IPDS-I Software (Stoe & Cie, 2000); data reduction: INTEGRATE in IPDS-I Software (Stoe & Cie, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. A content of asymmetric unit of (I) showing the atomic-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. | |
Fig. 2. Basic aggregation pattern in (I) viewed in [100]. Dashed lines denote hydrogen bonds. H atoms have been omitted for clarity. | |
Fig. 3. Head-to-tail sequences of zwitterionic glycine molecules in (I) viewed in [001]. Dashed lines denote hydrogen bonds. H atoms not involved in H-bonding were omitted for clarity. |
C2H5NO2·C8H6O4 | F(000) = 1008 |
Mr = 241.20 | Dx = 1.508 Mg m−3 |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 8000 reflections |
a = 7.9657 (5) Å | θ = 2.6–26.1° |
b = 11.3470 (7) Å | µ = 0.13 mm−1 |
c = 23.513 (2) Å | T = 173 K |
V = 2125.3 (3) Å3 | Block, colourless |
Z = 8 | 0.53 × 0.46 × 0.30 mm |
Stoe IPDS diffractometer | 1597 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.041 |
Graphite monochromator | θmax = 26.0°, θmin = 3.1° |
Detector resolution: 0.81Å pixels mm-1 | h = −9→9 |
phi rotation scans | k = −13→13 |
15716 measured reflections | l = −29→28 |
2077 independent reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.034 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.090 | w = 1/[σ2(Fo2) + (0.064P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.01 | (Δ/σ)max < 0.001 |
2077 reflections | Δρmax = 0.22 e Å−3 |
175 parameters | Δρmin = −0.19 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0086 (15) |
C2H5NO2·C8H6O4 | V = 2125.3 (3) Å3 |
Mr = 241.20 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 7.9657 (5) Å | µ = 0.13 mm−1 |
b = 11.3470 (7) Å | T = 173 K |
c = 23.513 (2) Å | 0.53 × 0.46 × 0.30 mm |
Stoe IPDS diffractometer | 1597 reflections with I > 2σ(I) |
15716 measured reflections | Rint = 0.041 |
2077 independent reflections |
R[F2 > 2σ(F2)] = 0.034 | 0 restraints |
wR(F2) = 0.090 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | Δρmax = 0.22 e Å−3 |
2077 reflections | Δρmin = −0.19 e Å−3 |
175 parameters |
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 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 > 2sigma(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 | ||
O3 | −0.06389 (12) | 0.23293 (9) | 0.08480 (4) | 0.0293 (3) | |
O4 | −0.00401 (15) | 0.40181 (9) | 0.12875 (4) | 0.0374 (3) | |
H4O | −0.058 (3) | 0.435 (2) | 0.0959 (11) | 0.075 (7)* | |
O5 | 0.00354 (13) | −0.05643 (9) | 0.12213 (4) | 0.0365 (3) | |
O6 | 0.19779 (12) | 0.05907 (9) | 0.08314 (4) | 0.0311 (3) | |
H6O | 0.205 (3) | −0.008 (2) | 0.0572 (10) | 0.072 (6)* | |
C3 | 0.06342 (15) | 0.22668 (12) | 0.17621 (5) | 0.0238 (3) | |
C4 | 0.10175 (15) | 0.10660 (12) | 0.17542 (5) | 0.0242 (3) | |
C5 | 0.15369 (17) | 0.05214 (13) | 0.22514 (6) | 0.0294 (3) | |
H5 | 0.1795 | −0.0296 | 0.2247 | 0.035* | |
C6 | 0.16855 (19) | 0.11483 (14) | 0.27541 (6) | 0.0347 (3) | |
H6 | 0.2054 | 0.0764 | 0.3091 | 0.042* | |
C7 | 0.12967 (18) | 0.23317 (14) | 0.27639 (6) | 0.0336 (3) | |
H7 | 0.1387 | 0.2765 | 0.3108 | 0.040* | |
C8 | 0.07751 (17) | 0.28854 (13) | 0.22713 (6) | 0.0278 (3) | |
H8 | 0.0508 | 0.3701 | 0.2280 | 0.033* | |
C9 | −0.00603 (16) | 0.28671 (12) | 0.12521 (5) | 0.0249 (3) | |
C10 | 0.09312 (16) | 0.03014 (11) | 0.12370 (5) | 0.0247 (3) | |
O1 | 0.75187 (11) | 0.11587 (8) | −0.01838 (4) | 0.0269 (2) | |
O2 | 0.65409 (12) | −0.01881 (8) | 0.04157 (4) | 0.0317 (3) | |
N1 | 0.59761 (16) | 0.29647 (10) | 0.03063 (5) | 0.0258 (3) | |
H1A | 0.543 (2) | 0.3538 (16) | 0.0511 (8) | 0.042 (5)* | |
H1B | 0.560 (2) | 0.2998 (17) | −0.0061 (9) | 0.051 (5)* | |
H1C | 0.704 (3) | 0.3178 (16) | 0.0329 (8) | 0.043 (5)* | |
C1 | 0.66689 (15) | 0.08474 (11) | 0.02398 (5) | 0.0226 (3) | |
C2 | 0.57097 (16) | 0.17890 (11) | 0.05551 (6) | 0.0249 (3) | |
H2A | 0.4497 | 0.1599 | 0.0546 | 0.030* | |
H2B | 0.6072 | 0.1798 | 0.0958 | 0.030* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O3 | 0.0348 (5) | 0.0245 (5) | 0.0286 (5) | −0.0013 (4) | −0.0052 (4) | −0.0042 (4) |
O4 | 0.0615 (7) | 0.0201 (6) | 0.0307 (6) | −0.0003 (5) | −0.0090 (5) | −0.0012 (4) |
O5 | 0.0476 (6) | 0.0296 (6) | 0.0322 (6) | −0.0152 (5) | 0.0070 (4) | −0.0067 (4) |
O6 | 0.0368 (5) | 0.0226 (5) | 0.0338 (5) | −0.0036 (4) | 0.0124 (4) | −0.0055 (4) |
C3 | 0.0231 (6) | 0.0230 (7) | 0.0251 (7) | −0.0023 (5) | 0.0022 (5) | −0.0020 (5) |
C4 | 0.0215 (6) | 0.0229 (7) | 0.0280 (7) | −0.0032 (5) | 0.0035 (5) | −0.0018 (5) |
C5 | 0.0318 (7) | 0.0250 (7) | 0.0315 (7) | 0.0004 (6) | 0.0006 (5) | 0.0024 (6) |
C6 | 0.0398 (8) | 0.0363 (9) | 0.0279 (7) | −0.0013 (6) | −0.0036 (6) | 0.0047 (6) |
C7 | 0.0408 (8) | 0.0355 (9) | 0.0245 (7) | −0.0047 (7) | −0.0017 (6) | −0.0044 (6) |
C8 | 0.0313 (7) | 0.0239 (7) | 0.0283 (7) | −0.0016 (5) | 0.0009 (5) | −0.0055 (5) |
C9 | 0.0269 (6) | 0.0213 (7) | 0.0266 (7) | −0.0011 (5) | 0.0014 (5) | −0.0026 (5) |
C10 | 0.0278 (6) | 0.0186 (7) | 0.0277 (7) | −0.0001 (5) | 0.0021 (5) | −0.0004 (5) |
O1 | 0.0323 (5) | 0.0227 (5) | 0.0256 (5) | −0.0013 (4) | 0.0069 (4) | −0.0038 (4) |
O2 | 0.0415 (6) | 0.0204 (5) | 0.0332 (5) | 0.0037 (4) | 0.0057 (4) | 0.0041 (4) |
N1 | 0.0293 (6) | 0.0192 (6) | 0.0288 (6) | 0.0010 (5) | 0.0024 (5) | −0.0043 (5) |
C1 | 0.0244 (6) | 0.0211 (7) | 0.0223 (6) | −0.0002 (5) | −0.0017 (5) | −0.0016 (5) |
C2 | 0.0283 (7) | 0.0216 (7) | 0.0247 (6) | −0.0002 (5) | 0.0040 (5) | −0.0012 (5) |
O3—C9 | 1.2197 (15) | C6—H6 | 0.9500 |
O4—C9 | 1.3088 (18) | C7—C8 | 1.382 (2) |
O4—H4O | 0.96 (3) | C7—H7 | 0.9500 |
O5—C10 | 1.2147 (16) | C8—H8 | 0.9500 |
O6—C10 | 1.3086 (16) | O1—C1 | 1.2550 (15) |
O6—H6O | 0.98 (2) | O2—C1 | 1.2498 (16) |
C3—C8 | 1.3925 (18) | N1—C2 | 1.4720 (17) |
C3—C4 | 1.396 (2) | N1—H1A | 0.917 (19) |
C3—C9 | 1.4859 (18) | N1—H1B | 0.91 (2) |
C4—C5 | 1.3855 (19) | N1—H1C | 0.88 (2) |
C4—C10 | 1.4955 (18) | C1—C2 | 1.5083 (18) |
C5—C6 | 1.385 (2) | C2—H2A | 0.9900 |
C5—H5 | 0.9500 | C2—H2B | 0.9900 |
C6—C7 | 1.378 (2) | ||
C9—O4—H4O | 109.8 (14) | O3—C9—C3 | 122.68 (13) |
C10—O6—H6O | 107.5 (13) | O4—C9—C3 | 113.67 (11) |
C8—C3—C4 | 119.06 (12) | O5—C10—O6 | 123.72 (12) |
C8—C3—C9 | 119.52 (12) | O5—C10—C4 | 121.39 (11) |
C4—C3—C9 | 121.20 (11) | O6—C10—C4 | 114.70 (11) |
C5—C4—C3 | 119.29 (12) | C2—N1—H1A | 111.5 (11) |
C5—C4—C10 | 116.18 (12) | C2—N1—H1B | 111.5 (12) |
C3—C4—C10 | 124.53 (12) | H1A—N1—H1B | 108.2 (16) |
C6—C5—C4 | 121.11 (13) | C2—N1—H1C | 111.3 (12) |
C6—C5—H5 | 119.4 | H1A—N1—H1C | 103.1 (16) |
C4—C5—H5 | 119.4 | H1B—N1—H1C | 110.9 (17) |
C7—C6—C5 | 119.71 (13) | O2—C1—O1 | 124.83 (12) |
C7—C6—H6 | 120.1 | O2—C1—C2 | 117.52 (11) |
C5—C6—H6 | 120.1 | O1—C1—C2 | 117.64 (11) |
C6—C7—C8 | 119.78 (13) | N1—C2—C1 | 111.94 (11) |
C6—C7—H7 | 120.1 | N1—C2—H2A | 109.2 |
C8—C7—H7 | 120.1 | C1—C2—H2A | 109.2 |
C7—C8—C3 | 121.05 (13) | N1—C2—H2B | 109.2 |
C7—C8—H8 | 119.5 | C1—C2—H2B | 109.2 |
C3—C8—H8 | 119.5 | H2A—C2—H2B | 107.9 |
O3—C9—O4 | 123.61 (13) | ||
C8—C3—C4—C5 | −0.36 (18) | C8—C3—C9—O3 | −159.60 (13) |
C9—C3—C4—C5 | −174.93 (12) | C4—C3—C9—O3 | 14.95 (19) |
C8—C3—C4—C10 | −179.55 (12) | C8—C3—C9—O4 | 18.29 (17) |
C9—C3—C4—C10 | 5.88 (19) | C4—C3—C9—O4 | −167.16 (12) |
C3—C4—C5—C6 | −0.2 (2) | C5—C4—C10—O5 | 59.45 (18) |
C10—C4—C5—C6 | 179.09 (12) | C3—C4—C10—O5 | −121.34 (15) |
C4—C5—C6—C7 | 0.6 (2) | C5—C4—C10—O6 | −115.59 (13) |
C5—C6—C7—C8 | −0.5 (2) | C3—C4—C10—O6 | 63.62 (17) |
C6—C7—C8—C3 | 0.0 (2) | O2—C1—C2—N1 | 179.74 (11) |
C4—C3—C8—C7 | 0.46 (19) | O1—C1—C2—N1 | −1.15 (17) |
C9—C3—C8—C7 | 175.12 (12) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O5i | 0.917 (19) | 1.992 (19) | 2.8398 (16) | 153.0 (16) |
N1—H1B···O3ii | 0.91 (2) | 2.13 (2) | 3.0219 (16) | 164.6 (17) |
N1—H1C···O2iii | 0.88 (2) | 2.181 (19) | 2.8934 (16) | 137.4 (15) |
N1—H1C···O3iv | 0.88 (2) | 2.416 (19) | 3.0681 (16) | 130.9 (15) |
O4—H4O···O2i | 0.96 (3) | 1.58 (3) | 2.5383 (14) | 175 (2) |
O6—H6O···O1v | 0.98 (2) | 1.56 (2) | 2.5337 (13) | 171 (2) |
Symmetry codes: (i) −x+1/2, y+1/2, z; (ii) x+1/2, −y+1/2, −z; (iii) −x+3/2, y+1/2, z; (iv) x+1, y, z; (v) −x+1, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | C2H5NO2·C8H6O4 |
Mr | 241.20 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 173 |
a, b, c (Å) | 7.9657 (5), 11.3470 (7), 23.513 (2) |
V (Å3) | 2125.3 (3) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.13 |
Crystal size (mm) | 0.53 × 0.46 × 0.30 |
Data collection | |
Diffractometer | Stoe IPDS |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 15716, 2077, 1597 |
Rint | 0.041 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.090, 1.01 |
No. of reflections | 2077 |
No. of parameters | 175 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.22, −0.19 |
Computer programs: EXPOSE in IPDS-I Software (Stoe & Cie, 2000), CELL in IPDS-I Software (Stoe & Cie, 2000), INTEGRATE in IPDS-I Software (Stoe & Cie, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009) and ORTEP-3 (Farrugia, 2012).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O5i | 0.917 (19) | 1.992 (19) | 2.8398 (16) | 153.0 (16) |
N1—H1B···O3ii | 0.91 (2) | 2.13 (2) | 3.0219 (16) | 164.6 (17) |
N1—H1C···O2iii | 0.88 (2) | 2.181 (19) | 2.8934 (16) | 137.4 (15) |
N1—H1C···O3iv | 0.88 (2) | 2.416 (19) | 3.0681 (16) | 130.9 (15) |
O4—H4O···O2i | 0.96 (3) | 1.58 (3) | 2.5383 (14) | 175 (2) |
O6—H6O···O1v | 0.98 (2) | 1.56 (2) | 2.5337 (13) | 171 (2) |
Symmetry codes: (i) −x+1/2, y+1/2, z; (ii) x+1/2, −y+1/2, −z; (iii) −x+3/2, y+1/2, z; (iv) x+1, y, z; (v) −x+1, −y, −z. |
Acknowledgements
TB thanks the University Grants Commission (UGC) for the award of a Research Fellowship under the Faculty Improvement Programme (FIP). We are grateful to Professor Helen Stoeckli-Evans, University of Neuchâtel, Switzerland, for measuring the X-ray diffraction data. ST thanks the management of SASTRA University for their encouragement.
References
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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.
As part of our studies on amino acids and carboxylic acids interactions (Sharma et al. 2006; Selvaraj et al., 2007), we report here the crystal structure of the title cocrystal of glycine and phthalic acid, (I).
The asymmetric unit of (I) contains one glycine molecule and one phthalic acid molecule (Fig. 1). The glycine molecule exists as a zwitterion with a positively charged amino group and a negatively charged carboxylate group as found in glycine-trimesic acid complex (Herbstein et al., 1981) and glycine-glutaric acid cocrystal (Losev et al., 2011), where glutaric acid exists as a neutral molecule. The phthalic acid exists as a neutral molecule with both carboxylic acid groups being unionized. The stoichiometry between the glycine and phthalic acid is 1:1.
The crystal packing is stabilized by a network of N—H···O and O—H···O hydrogen bonds (Table 1). As illustrated in Fig. 2, the basic aggregation pattern observed in the complex is a layered architecture of zwitterionic glycine and neutral phthalic acid molecules. An antiparallel linear array of zwitterionic glycines are sandwiched between phthalic acid layers.
In (I), the zwitterionic glycine has one donor atom capable of forming three hydrogen bonds, and one of them forms bifurcated hydrogen bonds, while neutral phthalic acid can also forms three hydrogen bonds through two acceptors (Table 1). In the crystal structure, the zwitterionic glycines are arranged in linear arrays along [010] direction. In each array, adjacent glycines are connected by a N1···O2 hydrogen bond which can be described as a head-to-tail sequence having a graph-set motif of C5 (Bernstein et al., 1995) (Fig. 3). In contrast to (I), no head-to-tail sequence was observed in glycine-glutaric acid cocrystal (Losev et al., 2011). As observed in many binary complexes of amino acids complexed with carboxylic acids, the neutral molecules in the complex do not interact among themselves. However, here, phthalic acid molecule is interconnected by zwitterionic glycines via two intermolecular N1···O3 hydrogen bonds. The glycine amino group acts as donor for 1-substituted carboxylic O3 atoms of the phthalic acid molecules emanating from different phthalic acids layers. Another carboxylic O5 atom acts as acceptor for an intermolecular hydrogen bond with the amino group of a glycine. The 2-substituted carboxylic group of the phthalic acid molecules in two different layers are interconnected by glycines. One carboxylic group in one layer interacts with the glycine in one layer, while its symmetry-related equivalents in the adjacent layers interacts with the glycine in the neighbouring layer [C12(4) graph-set motif]. The donor atoms (O4 and O6) of the phthalic acid molecule participate in intermolecular short and linear O—H···O hydrogen bonds with the carboxylate group of glycine. These hydrogen bonds produce C22(11) chains that run parallel to the a axis.