2-Amino-4,6-di­methyl­pyrimidine–sorbic acid (1/1)

Sundaramoorthy Gomathi; Packianathan Thomas Muthiah

doi:10.1107/S1600536813018175

. 2013 Jul 10;69(Pt 8):o1235. doi: 10.1107/S1600536813018175

2-Amino-4,6-dimethylpyrimidine–sorbic acid (1/1)

Sundaramoorthy Gomathi ^a, Packianathan Thomas Muthiah ^a,^*

PMCID: PMC3793739 PMID: 24109326

Abstract

In the crystal of the title compound, C₆H₉N₃·C₆H₈O₂, the 2-amino-4,6-dimethylpyrimidine and sorbic acid molecules are linked through N—H⋯O and O—H⋯N hydrogen bonds, which generate a cyclic bimolecular heterosynthon with an R ₂ ²(8) graph-set motif. Further, two inversion-related pyrimidine molecules are base-paired via a pair of N—H⋯N hydrogen bonds, forming a cyclic bimolecular homosynthon with a graph-set of R ₂ ²(8). A discrete hetero tetrameric supramolecular unit along the b axis is formed by the fusion of two heterosynthons and one homosynthon. An aromatic π–π interaction [centroid–centroid distance = 3.7945 (16) Å] is observed between these tetrameric units.

Related literature

For aminopyrimidine–carboxylic acid interactions, see: Hunt et al. (1980 ▶). For related structures, see: Thanigaimani et al. (2007 ▶); Ebenezer & Muthiah (2010 ▶, 2012 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶); Etter (1990 ▶). graphic file with name e-69-o1235-scheme1.jpg

Experimental

Crystal data

C₆H₉N₃·C₆H₈O₂
M _r = 235.29
Triclinic,
a = 7.8441 (6) Å
b = 9.9413 (8) Å
c = 10.2846 (13) Å
α = 112.058 (7)°
β = 98.333 (8)°
γ = 111.306 (5)°
V = 654.69 (13) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.12 × 0.11 × 0.09 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T _min = 0.990, T _max = 0.993
9667 measured reflections
2280 independent reflections
1585 reflections with I > 2σ(I)
R _int = 0.048

Refinement

R[F ² > 2σ(F ²)] = 0.069
wR(F ²) = 0.210
S = 1.03
2280 reflections
169 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶), Mercury (Macrae et al., 2008 ▶) and POV-RAY (Cason, 2004 ▶); software used to prepare material for publication: PLATON.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536813018175/is5286sup1.cif

e-69-o1235-sup1.cif^{(23KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813018175/is5286Isup2.hkl

e-69-o1235-Isup2.hkl^{(109.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯N1	0.99 (4)	1.70 (4)	2.674 (3)	167 (4)
N2—H2A⋯N3ⁱ	0.89 (3)	2.19 (3)	3.076 (4)	176 (2)
N2—H2B⋯O1	0.86 (4)	2.10 (4)	2.946 (4)	171 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

SG thanks the UGC–SAP, India, for the award of an RFSMS. The authors thank the DST India (FIST programme) for the use of Bruker SMART APEXII diffractometer at the School of Chemistry, Bharathidasan University, Tiruchirappalli, Tamilnadu, India.

supplementary crystallographic information

Comment

The non-covalent interactions of aminopyrimidine with carboxylic acid derivatives are of immense significance, since they involve in many molecular recognition process of biological functions and protein-drug binding (Hunt et al.,1980). Sorbic acid is an antibacterial agent and widely used as a preservatives. Several salts and co-crystals involving 2-amino-4,6-dimethoxy/dimethyl pyrimidine and various carboxylates (Ebenezer & Muthiah, 2010) have already been reported from our laboratory.

The current investigation focuses on the supramolecular hydrogen-bonded patterns exhibited by the (1:1) co-crystal of 2-amino-4,6-dimethylpyrimidine with sorbic acid. The asymmetric unit of the titled co-crystal consists of one molecule of 2-amino-4,6-dimethylpyrimidine (AMPY) and a molecule of sorbic acid (SA) (Fig. 1). The SA molecule exists in the EE configuration. The extended conformation of SA can be inferred from the four torsion angles, C9—C10—C11—C12 = -178.1 (3)°, C10—C11—C12—C13 = 175.5 (3)°, C11—C12—C13—C14 = -179.0 (3)° and O1—C9—C10—C11 = 168.8 (3)°. The values are in close agreement with those in the literature (Thanigaimani et al., 2007).

The primary supramolecular synthon is assembled via N—H···O and O—H···N hydrogen bonds between the carboxylic group of SA and the amino pyrimidine moiety of AMPY to form a cyclic bimolecular heterosynthon with an R₂²(8) graph-set motif (Etter, 1990; Bernstein et al., 1995). Two centrosymmetric AMPY molecules are self-assembled to form complementary base pairing via a pair of N—H···N hydrogen bonds to form another R₂²(8) ring motif. The complementary base pairing involves 2-amino group and ring N3ⁱ atom of inversion related pyrimidine moiety of AMPY. The primary and secondary interactions lead to the generation of a discrete and stable linear hetero tetramer along the b axis (Ebenezer & Muthiah, 2012) which is a four-component supramolecule formed by the fusion of two centrosymmetric bimolecular heterosynthons [R₂²(8)] and a homosynthon [R₂²(8)] (Fig. 2). These discrete linear hetero tetrameric units are arranged in two dimensional space as sheets without any neighbouring interactions in the same plane.

The pyrimidine moiety of inversion related linear heterotetrameric units present in the parallel planes are stacked by an aromatic π–π interaction in a head to tail fashion (Fig. 3) with the interplanar distance of 3.580 Å, centroid to centroid distance of 3.7945 (16) Å [Cg–Cgⁱ; symmetry code: (i) 1 - x,1 - y,1 - z] and the slip angle of 19.36°.

Experimental

Hot aqueous solutions of 2-amino-4, 6-dimethylpyrimidine (31 mg, Aldrich) and sorbic acid (28 mg, Sisco) were mixed in a 1:1 molar ratio. The resulting solution was warmed over a water bath for half an hour and then kept at room temperature for crystallization. After a week, colorless prismatic crystals were obtained.