Caffeine–N-phthaloyl-β-alanine (1/1)

Moazzam H Bhatti; Uzma Yunus; Syed Raza Shah; Ulrich Flörke

doi:10.1107/S1600536812022696

. 2012 May 26;68(Pt 6):o1888. doi: 10.1107/S1600536812022696

Caffeine–N-phthaloyl-β-alanine (1/1)

Moazzam H Bhatti ^a,^*, Uzma Yunus ^a, Syed Raza Shah ^a, Ulrich Flörke ^b

PMCID: PMC3379448 PMID: 22719646

Abstract

The title co-crystal [systematic name: 3-(1,3-dioxoisoindolin-2-yl)propanoic acid–1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione (1/1)], C₈H₁₀N₄O₂·C₁₁H₉NO₄, is the combination of 1:1 adduct of N-phthaloyl-β-alanine with caffeine. The phthalimide and purine rings in the N-phthaloyl-β-alanine and caffeine molecules are essentially planar, with r.m.s. deviations of the fitted atoms of 0.0078 and 0.0118 Å, respectively. In the crystal, the two molecules are linked via an O—H⋯N hydrogen bond involving the intact carboxylic acid (COOH) group. The crystal structure is consolidated by C—H⋯O interactions. The H atoms of a methyl group of the caffeine molecule are disordered over two sets of sites of equal occupancy.

Related literature

For related structures, see: Bhatti et al. (2011 ▶); Feeder & Jones (1996 ▶).

Experimental

Crystal data

C₈H₁₀N₄O₂·C₁₁H₉NO₄
M _r = 413.39
Triclinic,
a = 8.3411 (17) Å
b = 9.0638 (18) Å
c = 13.162 (3) Å
α = 77.105 (4)°
β = 82.394 (4)°
γ = 72.865 (4)°
V = 924.6 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 130 K
0.42 × 0.40 × 0.35 mm

Data collection

Bruker SMART APEX diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T _min = 0.954, T _max = 0.962
8826 measured reflections
4378 independent reflections
3752 reflections with I > 2σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.106
S = 1.03
4378 reflections
277 parameters
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: SMART (Bruker, 2002 ▶); cell refinement: SAINT (Bruker, 2002 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL and local programs.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812022696/pv2544sup1.cif

e-68-o1888-sup1.cif^{(22.5KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812022696/pv2544Isup2.hkl

e-68-o1888-Isup2.hkl^{(214.5KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812022696/pv2544Isup3.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
O4—H4⋯N3ⁱ	0.84	1.83	2.6672 (13)	175
C3—H3A⋯O5ⁱⁱ	0.95	2.26	3.1447 (16)	155
C6—H6A⋯O3ⁱⁱⁱ	0.95	2.31	3.2283 (16)	162
C20—H20B⋯O6^iv	0.98	2.35	3.2559 (16)	154

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

Acknowledgments

The authors gratefully acknowledge Allama Iqbal Open University, Islamabad, Pakistan, for providing research facilities.

supplementary crystallographic information

Comment

Previously we have reported the synthesis and crystal structure of a 1:1 adduct of N-phthaloylglycine with caffeine (Bhatti et al., 2011). Now we have synthesized a 1:1 adduct of N-phthaloyl-β-alanine with caffeine and determined its crystal structure which is reported in this article.

The asymmetric unit of the title adduct is presented in Figure 1. The phthalimide and purine rings in the N-phthaloyl-β-alanine and caffeine molecules are essentailly planar with rms deviations of fitted atoms 0.0078 and 0.0118 Å, respectively; the dihedral angle between the mean-planes of these rings is 5.59 (5)°. The dihedral angle between phthlimide and propanoic acid is 6.5 (1)° slightly less than reported value of N-phthaloyl-β-alanine (Feeder & Jones, 1996). The carbon oxygen distance in the carboxylic acid group (COOH) show typical double and single bond values [C11—O3 = 1.2066 (15) Å and C11—O4 = 1.3312 (14) Å, respectively)], indicating intact protonation of carboxylic acid group. This is further strengthened by intermolecular O4—H4···N3 hydrogen bonding which link the two molecules (Fig. 2). The crystal structure is further consolidated by C—H···O type intermolecular interactions (Table 1).

Experimental

A mixture of N-phthaloyl-β-alanine (0.01 mol) and caffeine (0.01 mol) was heated in water (100 ml) for 2 h. The hot solution was filtered and the filtrate was set aside for one week. Colourless needle like crystals were obtained suitable for X-ray analysis.