Benzene-1,2,4,5-tetra­carb­oxy­lic acid bis­(1,3,7-trimethyl-2,3,6,7-tetra­hydro-1H-purine-2,6-dione)

Hadi D Arman; Edward R T Tiekink

doi:10.1107/S1600536813022563

. 2013 Aug 17;69(Pt 9):o1443. doi: 10.1107/S1600536813022563

Benzene-1,2,4,5-tetracarboxylic acid bis(1,3,7-trimethyl-2,3,6,7-tetrahydro-1H-purine-2,6-dione)

Hadi D Arman ^a, Edward R T Tiekink ^b,^*

PMCID: PMC3884421 PMID: 24427071

Abstract

The asymmetric unit of the title co-crystal, C₁₀H₆O₈·2C₈H₁₀N₄O₂, comprises a centrosymmetric benzene-1,2,4,5-tetracarboxylic acid (LH₄) molecule and a molecule of caffeine in a general position. LH₄ is nonplanar, with the dihedral angles between the ring and pendent carboxylic acid groups being 44.22 (7) and 49.74 (7)°. By contrast, the caffeine molecule is planar (r.m.s. deviation = 0.040 Å). Supramolecular layers parallel to (-1-10) are sustained by carboxylic acid O—H⋯O(carbonyl) and O—H⋯N(imidazole) hydrogen bonds, as well as by methyl–carbonyl C—H⋯O interactions. These stack via π–π interactions between the benzene and imidazole rings [inter-centroid distance = 3.4503 (10) Å].

Related literature

For cocrystallization studies with benzene-1,2,4,5-tetracarboxylic acid, see: Arman & Tiekink (2013 ▶). graphic file with name e-69-o1443-scheme1.jpg

Experimental

Crystal data

C₁₀H₆O₈·2C₈H₁₀N₄O₂
M _r = 642.55
Triclinic,
a = 7.4570 (15) Å
b = 9.0490 (15) Å
c = 11.782 (2) Å
α = 68.800 (11)°
β = 81.124 (13)°
γ = 73.441 (9)°
V = 709.3 (2) Å³
Z = 1
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 98 K
0.55 × 0.30 × 0.25 mm

Data collection

Rigaku AFC12 Kappa/SATURN724 diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.838, T _max = 1
4935 measured reflections
3213 independent reflections
3006 reflections with I > 2σ(I)
R _int = 0.020
Standard reflections: 0

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.120
S = 1.04
3213 reflections
218 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Data collection: CrystalClear (Molecular Structure Corporation & Rigaku, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPII (Johnson, 1976 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536813022563/hg5340sup1.cif

e-69-o1443-sup1.cif^{(18.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813022563/hg5340Isup2.hkl

e-69-o1443-Isup2.hkl^{(154.4KB, hkl)}

Click here for additional data file.^{(11.8KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536813022563/hg5340Isup3.cml

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—H1O⋯N3ⁱ	0.86 (1)	1.83 (1)	2.6774 (17)	171 (2)
O4—H2O⋯O5	0.84 (2)	1.84 (2)	2.6571 (15)	162 (2)
C12—H12B⋯O6ⁱⁱ	0.98	2.30	3.239 (2)	159

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The authors gratefully thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (grant No. UM.C/HIR-MOHE/SC/03).

supplementary crystallographic information

1. Comment

The title co-crystal was investigated in continuation of recent structural studies of the products obtained from the co-crystallization of benzene-1,2,4,5-tetracarboxylic acid (LH₄) with various pyridyl-containing molecules (Arman & Tiekink, 2013).

The asymmetric unit comprises half a molecule of LH₄, being disposed about a centre of inversion, and a molecule of caffeine in a general position, Fig. 1. Twists are evident in LH₄ as seen in the dihedral angles of 44.22 (7) and 49.74 (7)° formed, respectively, between the O1- and O3-carboxylic acids and the benzene ring to which they are attached. The 14 non-hydrogen atoms of the caffeine molecule are co-planar with an r.m.s. deviation = 0.040 Å.

In the crystal packing, the HL₄ molecule forms two O2—H···O5-carbonyl and two O4—H···N3-imidazole hydrogen bonds to form a supramolecular chain constructed about centrosymmetric 26-membered {···HO—C₄OH···OCNCN}₂ synthons, Table 1. Chains are connected into a layer approximately parallel to (110) by methyl-C12—H···O6(carbonyl) interactions via centrosymmetric and 10-membered {···OCNCH}₂ synthons, Fig. 2. Layers are connected into a three-dimensional architecture by π–π interactions between the benzene and imidazolyl rings [inter-centroid distance = 3.4503 (10) Å, angle of inclination = 9.54 (7)° for symmetry operation x, y, 1 + z], Fig. 3.

2. Experimental

Crystals of (I) were obtained by the co-crystallization of caffeine (Sigma–Aldrich, 0.08 mmol) and benzene-1,2,4,5-tetracarboxylic acid (Sigma–Aldrich, 0.09 mmol) in acetone solution. Crystals were obtained by slow evaporation.