organic compounds
3-Carboxyphenylboronic acid–theophylline (1/1)
aBulgarian Academy of Sciences, Institute of Mineralogy and Crystallography, Acad G. Bonchev str. build. 107, 1113 Sofia, Bulgaria
*Correspondence e-mail: blshivachev@gmail.com
The title two-component molecular crystal [systematic name: 3-(dihydroxyboranyl)benzoic acid–1,3-dimethyl-7H-purine-2,6-dione (1/1)], C7H7BO4·C7H8N4O2, comprises theophylline and 3-carboxyphenylboronic acid molecules in a 1:1 molar ratio. In the crystal, molecules are self-assembled by O—H⋯O and N—H⋯N hydrogen bonds, generating layers parallel to (-209). The layers are stacked through π–π [centroid–centroid distance = 3.546 (2) Å] and C—H⋯π interactions.
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536812029467/kp2425sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812029467/kp2425Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536812029467/kp2425Isup3.cml
Crystals of the title compound were obtained by slow evaporation of a 1:1 mol. mixture of theophylline and 3-carboxyphenyl boronic acid in water/MeOH (1:1 v/v) at room temperature.
All H atoms were placed in idealized positions (C—Haromatic = 0.93 Å; C—Hmethyl = 0.96 Å; N—H = 0.86 Å and O—H = 0.82 Å) and were constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C or N) and Uĩso~(H) = 1.5Ueq(O)
Theophylline (1,3-dimethyl-1H-purine-2,6(3H,7H)-dione) is a xanthine derivative chemically similar to caffeine and theobromine (Barnes, 2003). Apart from new perspectives in organic chemistry, (e.g. Suzuki coupling reactions)
are emerging in the fields of crystal engineering, biochemistry and medicinal chemistry. In most cases the usage of the Active Pharmaceutical Ingredients (APIs) has been routinely restricted to salts, polymorphs, hydrates or solvates form (Brittain, 1999). Here we present the structure of the two-component molecular crystal theophylline (THEO) and 3-carboxyphenyl boronic acid (CPHB).The ring systems are nearly planar with r.m.s. of 0.0045 and 0.0172 for the phenyl (C2/C3/C4/C5/C6/C7) and purine (C11/N4/C8/N1/C12/N2/C9/C10/N3) moieties. The boronic group is slightly twisted from the phenyl plane (the angle between the mean planes of the phenyl and B1/O3/O4 is 6.93 (8) °). The angle between the phenyl and purine mean planes of the two molecules is 4.52 (5) ° (Fig. 1). In the π and π–π interactions (Fig. 3): (i) an almost parallel π-π stacking involving the PHB and THEO aromatic rings (offset of 1.04 Å and distance separation of 3.546 Å between C2/C3/C4/C5/C6/C7 and C8/C9/C10N3/C11/N4 ring centroids); (ii) an offset π–π interaction between C2/C3/C4/C5/C6/C7 and N1/C12/N2/C9/C10/N3/C11/N4/C8 rings (with distance separation and offset for afore mentioned centroids of 4.603 and 3.18 Å respectively); (iii) a CHmethyl···..π interaction (C14···..CPHB ring, with C14 to C2/C3/C4/C5/C6/C7 centroid distance of 3.483 Å), and (iv) a T-shape CHmethyl···π interaction between C13 and CPHB aromatic ring (with shortest distance, C13···C4 of 3.582 (4) Å) (Fig. 3).
neighbouring CPHB molecules form dimmers through O2—H2···O3 hydrogen bond and thus R2,2(16) motif is observed (Table 1). Adjacent dimmers are linked through O3—H3···O1 bond and thus a tetramer of CPHB is generated [R4,4(12) motif]. The O3—H3···O1 bond produces C1,1(8) chains that propagate along b axis. The THEO molecules are linked together by N2—H2A···N1 hydrogen bond producing C1,1(4) chain that propagate along b axis (Fig. 2). The CPHB and THEO molecules (chains) are linked via O4—H4···O11 hydrogen bond and form layers parallel to the plane (-2 0 9) (interlayer distance of 3.507 Å). In addition to the extensive hydrogen bonding the structure reveals weak CH3···For background to theophylline and
see: Barnes (2003); Brittain (1999).Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell
CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).Fig. 1. Molecular structure of the title compound, with atom-numbering scheme and 50% probability displacement ellipsoids. | |
Fig. 2. Crystal packing of the title compound. Hydrogen bonds are shown by dashed lines. Symmetry codes are used: (i) 1 - x, 1 - y, 1 - z; (ii)x, 1 + y, z; (iii) x - 1, y, z; (iv)x, y - 1, z. | |
Fig. 3. Projection of the structure showing the interactions (π–π and CH3···π) within the layers, denoted by dotted lines. Symmetry codes are: (i) 2 - x, 2 - y, 1 - z; (ii) x, 3/2 - y, 1/2 + z. |
C7H7BO4·C7H8N4O2 | F(000) = 720 |
Mr = 346.11 | Dx = 1.511 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 13.185 (4) Å | Cell parameters from 22 reflections |
b = 9.189 (3) Å | θ = 18.4–19.8° |
c = 13.287 (4) Å | µ = 0.12 mm−1 |
β = 109.04 (3)° | T = 290 K |
V = 1521.7 (8) Å3 | Prism, colourless |
Z = 4 | 0.32 × 0.3 × 0.28 mm |
Enraf–Nonius CAD-4 diffractometer | Rint = 0.037 |
Radiation source: Enraf–Nonius FR590 | θmax = 26.0°, θmin = 1.6° |
Graphite monochromator | h = 0→16 |
non–profiled ω/2τ scans | k = −11→11 |
5890 measured reflections | l = −16→15 |
2972 independent reflections | 3 standard reflections every 120 min |
1949 reflections with I > 2σ(I) | 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)] = 0.050 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.145 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0783P)2 + 0.0279P] where P = (Fo2 + 2Fc2)/3 |
2972 reflections | (Δ/σ)max < 0.001 |
231 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
C7H7BO4·C7H8N4O2 | V = 1521.7 (8) Å3 |
Mr = 346.11 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.185 (4) Å | µ = 0.12 mm−1 |
b = 9.189 (3) Å | T = 290 K |
c = 13.287 (4) Å | 0.32 × 0.3 × 0.28 mm |
β = 109.04 (3)° |
Enraf–Nonius CAD-4 diffractometer | Rint = 0.037 |
5890 measured reflections | 3 standard reflections every 120 min |
2972 independent reflections | intensity decay: none |
1949 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.050 | 0 restraints |
wR(F2) = 0.145 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.30 e Å−3 |
2972 reflections | Δρmin = −0.27 e Å−3 |
231 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 | ||
C1 | 0.61757 (18) | 0.7493 (2) | 0.51103 (18) | 0.0351 (5) | |
C2 | 0.70843 (17) | 0.6460 (2) | 0.52797 (17) | 0.0325 (5) | |
C3 | 0.81135 (18) | 0.7002 (2) | 0.54821 (18) | 0.0386 (6) | |
H3A | 0.8229 | 0.8001 | 0.5496 | 0.046* | |
C4 | 0.89597 (19) | 0.6057 (3) | 0.5661 (2) | 0.0448 (6) | |
H4 | 0.965 | 0.6416 | 0.5788 | 0.054* | |
C5 | 0.87869 (18) | 0.4568 (2) | 0.56527 (19) | 0.0395 (6) | |
H5 | 0.937 | 0.3944 | 0.5777 | 0.047* | |
C6 | 0.77718 (18) | 0.3978 (2) | 0.54645 (18) | 0.0335 (5) | |
C7 | 0.69213 (17) | 0.4961 (2) | 0.52676 (17) | 0.0322 (5) | |
H7 | 0.6228 | 0.4606 | 0.5125 | 0.039* | |
B1 | 0.7584 (2) | 0.2280 (3) | 0.5481 (2) | 0.0366 (6) | |
O1 | 0.62796 (14) | 0.87975 (16) | 0.51616 (15) | 0.0515 (5) | |
O2 | 0.52453 (13) | 0.68396 (17) | 0.49021 (17) | 0.0531 (5) | |
H2 | 0.4779 | 0.7446 | 0.4868 | 0.08* | |
O3 | 0.65614 (12) | 0.17673 (16) | 0.51923 (15) | 0.0450 (5) | |
H3 | 0.6572 | 0.0876 | 0.522 | 0.067* | |
O4 | 0.83877 (13) | 0.12910 (17) | 0.57757 (16) | 0.0512 (5) | |
H4A | 0.8966 | 0.1715 | 0.5996 | 0.077* | |
C8 | 0.66439 (16) | 0.8169 (2) | 0.27274 (17) | 0.0308 (5) | |
C9 | 0.65008 (17) | 0.9642 (2) | 0.27539 (18) | 0.0328 (5) | |
C10 | 0.73564 (17) | 1.0648 (2) | 0.29647 (19) | 0.0356 (5) | |
C11 | 0.85224 (17) | 0.8449 (2) | 0.31589 (18) | 0.0353 (5) | |
C12 | 0.49854 (19) | 0.8503 (2) | 0.2413 (2) | 0.0423 (6) | |
H12 | 0.4256 | 0.8334 | 0.2265 | 0.051* | |
C13 | 0.93062 (19) | 1.0874 (3) | 0.3434 (2) | 0.0505 (7) | |
H13A | 0.9747 | 1.0576 | 0.3021 | 0.076* | |
H13B | 0.9706 | 1.0788 | 0.4178 | 0.076* | |
H13C | 0.909 | 1.1868 | 0.3271 | 0.076* | |
C14 | 0.7768 (2) | 0.5983 (2) | 0.2817 (2) | 0.0427 (6) | |
H14A | 0.7807 | 0.5529 | 0.348 | 0.064* | |
H14B | 0.8414 | 0.5786 | 0.2659 | 0.064* | |
H14C | 0.7164 | 0.5602 | 0.2259 | 0.064* | |
N1 | 0.57032 (15) | 0.7444 (2) | 0.25156 (16) | 0.0385 (5) | |
N2 | 0.54161 (14) | 0.9822 (2) | 0.25452 (16) | 0.0393 (5) | |
H2A | 0.5082 | 1.0635 | 0.2507 | 0.047* | |
N3 | 0.83506 (14) | 0.9941 (2) | 0.31754 (16) | 0.0372 (5) | |
N4 | 0.76421 (14) | 0.75608 (19) | 0.29013 (14) | 0.0327 (4) | |
O10 | 0.72989 (13) | 1.19763 (17) | 0.29774 (16) | 0.0522 (5) | |
O11 | 0.94299 (12) | 0.79504 (18) | 0.33659 (15) | 0.0497 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0373 (13) | 0.0233 (11) | 0.0456 (14) | −0.0044 (9) | 0.0150 (10) | 0.0005 (10) |
C2 | 0.0348 (12) | 0.0228 (11) | 0.0406 (13) | −0.0039 (9) | 0.0135 (10) | −0.0034 (9) |
C3 | 0.0385 (13) | 0.0252 (11) | 0.0512 (15) | −0.0084 (10) | 0.0134 (11) | −0.0032 (10) |
C4 | 0.0294 (13) | 0.0360 (13) | 0.0674 (18) | −0.0112 (10) | 0.0135 (12) | −0.0036 (12) |
C5 | 0.0293 (12) | 0.0322 (12) | 0.0562 (15) | 0.0027 (10) | 0.0128 (11) | 0.0011 (11) |
C6 | 0.0314 (12) | 0.0257 (11) | 0.0430 (13) | −0.0013 (9) | 0.0117 (10) | −0.0002 (9) |
C7 | 0.0273 (11) | 0.0234 (11) | 0.0476 (14) | −0.0055 (9) | 0.0145 (10) | −0.0010 (9) |
B1 | 0.0303 (13) | 0.0266 (13) | 0.0516 (17) | 0.0023 (10) | 0.0117 (12) | 0.0004 (11) |
O1 | 0.0522 (11) | 0.0198 (8) | 0.0809 (13) | −0.0022 (7) | 0.0195 (10) | −0.0018 (8) |
O2 | 0.0342 (10) | 0.0248 (8) | 0.1026 (15) | 0.0009 (7) | 0.0254 (10) | −0.0011 (9) |
O3 | 0.0310 (9) | 0.0195 (8) | 0.0829 (13) | 0.0010 (6) | 0.0164 (8) | 0.0006 (8) |
O4 | 0.0307 (9) | 0.0272 (9) | 0.0902 (14) | 0.0027 (7) | 0.0123 (9) | 0.0057 (8) |
C8 | 0.0260 (11) | 0.0255 (11) | 0.0398 (12) | 0.0004 (9) | 0.0091 (9) | 0.0026 (9) |
C9 | 0.0282 (11) | 0.0248 (11) | 0.0455 (13) | 0.0022 (9) | 0.0122 (10) | 0.0031 (9) |
C10 | 0.0294 (12) | 0.0278 (12) | 0.0494 (14) | −0.0012 (9) | 0.0127 (10) | 0.0017 (10) |
C11 | 0.0285 (12) | 0.0336 (12) | 0.0412 (13) | 0.0033 (10) | 0.0080 (10) | 0.0048 (10) |
C12 | 0.0278 (12) | 0.0291 (12) | 0.0680 (16) | −0.0024 (10) | 0.0128 (11) | 0.0022 (11) |
C13 | 0.0320 (13) | 0.0371 (13) | 0.0774 (19) | −0.0100 (10) | 0.0112 (13) | 0.0001 (12) |
C14 | 0.0411 (14) | 0.0251 (12) | 0.0592 (16) | 0.0055 (10) | 0.0127 (12) | −0.0003 (10) |
N1 | 0.0283 (10) | 0.0258 (9) | 0.0583 (13) | −0.0013 (8) | 0.0101 (9) | 0.0024 (9) |
N2 | 0.0274 (10) | 0.0228 (9) | 0.0651 (13) | 0.0017 (7) | 0.0117 (9) | 0.0022 (9) |
N3 | 0.0254 (9) | 0.0297 (10) | 0.0535 (12) | −0.0035 (8) | 0.0088 (8) | 0.0009 (9) |
N4 | 0.0269 (9) | 0.0239 (9) | 0.0465 (11) | 0.0026 (7) | 0.0106 (8) | 0.0023 (8) |
O10 | 0.0411 (10) | 0.0232 (9) | 0.0913 (14) | −0.0022 (7) | 0.0203 (9) | −0.0017 (8) |
O11 | 0.0258 (9) | 0.0420 (10) | 0.0761 (13) | 0.0071 (7) | 0.0097 (8) | 0.0067 (8) |
C1—O1 | 1.206 (3) | C8—N4 | 1.378 (3) |
C1—O2 | 1.312 (3) | C9—N2 | 1.375 (3) |
C1—C2 | 1.487 (3) | C9—C10 | 1.414 (3) |
C2—C3 | 1.387 (3) | C10—O10 | 1.223 (3) |
C2—C7 | 1.393 (3) | C10—N3 | 1.407 (3) |
C3—C4 | 1.372 (3) | C11—O11 | 1.226 (3) |
C3—H3A | 0.93 | C11—N4 | 1.368 (3) |
C4—C5 | 1.386 (3) | C11—N3 | 1.391 (3) |
C4—H4 | 0.93 | C12—N2 | 1.326 (3) |
C5—C6 | 1.389 (3) | C12—N1 | 1.333 (3) |
C5—H5 | 0.93 | C12—H12 | 0.93 |
C6—C7 | 1.397 (3) | C13—N3 | 1.469 (3) |
C6—B1 | 1.581 (3) | C13—H13A | 0.96 |
C7—H7 | 0.93 | C13—H13B | 0.96 |
B1—O4 | 1.353 (3) | C13—H13C | 0.96 |
B1—O3 | 1.360 (3) | C14—N4 | 1.468 (3) |
O2—H2 | 0.82 | C14—H14A | 0.96 |
O3—H3 | 0.82 | C14—H14B | 0.96 |
O4—H4A | 0.82 | C14—H14C | 0.96 |
C8—N1 | 1.354 (3) | N2—H2A | 0.86 |
C8—C9 | 1.369 (3) | ||
O1—C1—O2 | 123.2 (2) | N2—C9—C10 | 132.2 (2) |
O1—C1—C2 | 123.7 (2) | O10—C10—N3 | 121.1 (2) |
O2—C1—C2 | 113.07 (18) | O10—C10—C9 | 127.3 (2) |
C3—C2—C7 | 119.7 (2) | N3—C10—C9 | 111.63 (18) |
C3—C2—C1 | 119.28 (19) | O11—C11—N4 | 121.3 (2) |
C7—C2—C1 | 121.04 (19) | O11—C11—N3 | 121.1 (2) |
C4—C3—C2 | 119.7 (2) | N4—C11—N3 | 117.57 (19) |
C4—C3—H3A | 120.2 | N2—C12—N1 | 113.3 (2) |
C2—C3—H3A | 120.2 | N2—C12—H12 | 123.4 |
C3—C4—C5 | 120.1 (2) | N1—C12—H12 | 123.4 |
C3—C4—H4 | 120 | N3—C13—H13A | 109.5 |
C5—C4—H4 | 120 | N3—C13—H13B | 109.5 |
C4—C5—C6 | 122.2 (2) | H13A—C13—H13B | 109.5 |
C4—C5—H5 | 118.9 | N3—C13—H13C | 109.5 |
C6—C5—H5 | 118.9 | H13A—C13—H13C | 109.5 |
C5—C6—C7 | 116.63 (19) | H13B—C13—H13C | 109.5 |
C5—C6—B1 | 122.0 (2) | N4—C14—H14A | 109.5 |
C7—C6—B1 | 121.4 (2) | N4—C14—H14B | 109.5 |
C2—C7—C6 | 121.7 (2) | H14A—C14—H14B | 109.5 |
C2—C7—H7 | 119.1 | N4—C14—H14C | 109.5 |
C6—C7—H7 | 119.1 | H14A—C14—H14C | 109.5 |
O4—B1—O3 | 117.4 (2) | H14B—C14—H14C | 109.5 |
O4—B1—C6 | 123.7 (2) | C12—N1—C8 | 103.52 (18) |
O3—B1—C6 | 118.9 (2) | C12—N2—C9 | 106.80 (19) |
C1—O2—H2 | 109.5 | C12—N2—H2A | 126.6 |
B1—O3—H3 | 109.5 | C9—N2—H2A | 126.6 |
B1—O4—H4A | 109.5 | C11—N3—C10 | 126.73 (18) |
N1—C8—C9 | 111.54 (19) | C11—N3—C13 | 116.56 (18) |
N1—C8—N4 | 126.55 (19) | C10—N3—C13 | 116.70 (18) |
C9—C8—N4 | 121.91 (19) | C11—N4—C8 | 119.09 (18) |
C8—C9—N2 | 104.89 (19) | C11—N4—C14 | 120.05 (18) |
C8—C9—C10 | 122.96 (19) | C8—N4—C14 | 120.86 (18) |
O1—C1—C2—C3 | −1.7 (4) | C8—C9—C10—N3 | −2.1 (3) |
O2—C1—C2—C3 | 178.5 (2) | N2—C9—C10—N3 | 177.6 (2) |
O1—C1—C2—C7 | 176.4 (2) | N2—C12—N1—C8 | 0.1 (3) |
O2—C1—C2—C7 | −3.3 (3) | C9—C8—N1—C12 | 0.0 (3) |
C7—C2—C3—C4 | 0.5 (4) | N4—C8—N1—C12 | −180.0 (2) |
C1—C2—C3—C4 | 178.7 (2) | N1—C12—N2—C9 | −0.2 (3) |
C2—C3—C4—C5 | −0.8 (4) | C8—C9—N2—C12 | 0.2 (3) |
C3—C4—C5—C6 | 0.2 (4) | C10—C9—N2—C12 | −179.6 (2) |
C4—C5—C6—C7 | 0.8 (4) | O11—C11—N3—C10 | −179.4 (2) |
C4—C5—C6—B1 | −178.6 (2) | N4—C11—N3—C10 | 0.8 (3) |
C3—C2—C7—C6 | 0.6 (3) | O11—C11—N3—C13 | 1.0 (3) |
C1—C2—C7—C6 | −177.6 (2) | N4—C11—N3—C13 | −178.8 (2) |
C5—C6—C7—C2 | −1.2 (3) | O10—C10—N3—C11 | −178.2 (2) |
B1—C6—C7—C2 | 178.3 (2) | C9—C10—N3—C11 | 1.9 (3) |
C5—C6—B1—O4 | 6.6 (4) | O10—C10—N3—C13 | 1.4 (3) |
C7—C6—B1—O4 | −172.8 (2) | C9—C10—N3—C13 | −178.5 (2) |
C5—C6—B1—O3 | −173.9 (2) | O11—C11—N4—C8 | 176.8 (2) |
C7—C6—B1—O3 | 6.7 (4) | N3—C11—N4—C8 | −3.4 (3) |
N1—C8—C9—N2 | −0.1 (3) | O11—C11—N4—C14 | −3.0 (3) |
N4—C8—C9—N2 | 179.9 (2) | N3—C11—N4—C14 | 176.9 (2) |
N1—C8—C9—C10 | 179.7 (2) | N1—C8—N4—C11 | −176.7 (2) |
N4—C8—C9—C10 | −0.3 (4) | C9—C8—N4—C11 | 3.2 (3) |
C8—C9—C10—O10 | 178.0 (2) | N1—C8—N4—C14 | 3.0 (3) |
N2—C9—C10—O10 | −2.3 (4) | C9—C8—N4—C14 | −177.0 (2) |
Cg is the centroif of the C2–C7 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O1i | 0.82 | 1.94 | 2.753 (2) | 168 |
O2—H2···O3ii | 0.82 | 1.89 | 2.671 (2) | 160 |
O4—H4A···O11iii | 0.82 | 2.03 | 2.815 (3) | 160 |
N2—H2A···N1iv | 0.86 | 1.95 | 2.812 (3) | 177 |
C14—H14A···Cg | 0.96 | 2.59 | 3.483 (3) | 155 |
Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+1, −z+1; (iii) −x+2, −y+1, −z+1; (iv) −x+1, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C7H7BO4·C7H8N4O2 |
Mr | 346.11 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 290 |
a, b, c (Å) | 13.185 (4), 9.189 (3), 13.287 (4) |
β (°) | 109.04 (3) |
V (Å3) | 1521.7 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.32 × 0.3 × 0.28 |
Data collection | |
Diffractometer | Enraf–Nonius CAD-4 |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5890, 2972, 1949 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.616 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.050, 0.145, 1.03 |
No. of reflections | 2972 |
No. of parameters | 231 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.30, −0.27 |
Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).
Cg is the centroif of the C2–C7 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O1i | 0.82 | 1.94 | 2.753 (2) | 168.3 |
O2—H2···O3ii | 0.82 | 1.89 | 2.671 (2) | 159.7 |
O4—H4A···O11iii | 0.82 | 2.03 | 2.815 (3) | 160.4 |
N2—H2A···N1iv | 0.86 | 1.95 | 2.812 (3) | 176.9 |
C14—H14A···Cg | 0.96 | 2.59 | 3.483 (3) | 155 |
Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+1, −z+1; (iii) −x+2, −y+1, −z+1; (iv) −x+1, y+1/2, −z+1/2. |
Acknowledgements
This work was supported by Bulgarian National Fund of Scientific Research contract DRNF 02/1.
References
Barnes, P. J. (2003). Am. J. Respir. Crit. Care Med. 167, 813–818. Web of Science CrossRef PubMed Google Scholar
Brittain, H. G. (1999). In Polymorphism in Pharmaceutical Solids. Boca Raton, FL: Informa Health Care. Google Scholar
Enraf–Nonius (1994). CAD-4 EXPRESS. Enraf–Nonius, Delft, The Netherlands. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. 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.
Theophylline (1,3-dimethyl-1H-purine-2,6(3H,7H)-dione) is a xanthine derivative chemically similar to caffeine and theobromine (Barnes, 2003). Apart from new perspectives in organic chemistry, (e.g. Suzuki coupling reactions) boronic acids are emerging in the fields of crystal engineering, biochemistry and medicinal chemistry. In most cases the usage of the Active Pharmaceutical Ingredients (APIs) has been routinely restricted to salts, polymorphs, hydrates or solvates form (Brittain, 1999). Here we present the structure of the two-component molecular crystal theophylline (THEO) and 3-carboxyphenyl boronic acid (CPHB).
The ring systems are nearly planar with r.m.s. of 0.0045 and 0.0172 for the phenyl (C2/C3/C4/C5/C6/C7) and purine (C11/N4/C8/N1/C12/N2/C9/C10/N3) moieties. The boronic group is slightly twisted from the phenyl plane (the angle between the mean planes of the phenyl and B1/O3/O4 is 6.93 (8) °). The angle between the phenyl and purine mean planes of the two molecules is 4.52 (5) ° (Fig. 1). In the crystal structure neighbouring CPHB molecules form dimmers through O2—H2···O3 hydrogen bond and thus R2,2(16) motif is observed (Table 1). Adjacent dimmers are linked through O3—H3···O1 bond and thus a tetramer of CPHB is generated [R4,4(12) motif]. The O3—H3···O1 bond produces C1,1(8) chains that propagate along b axis. The THEO molecules are linked together by N2—H2A···N1 hydrogen bond producing C1,1(4) chain that propagate along b axis (Fig. 2). The CPHB and THEO molecules (chains) are linked via O4—H4···O11 hydrogen bond and form layers parallel to the plane (-2 0 9) (interlayer distance of 3.507 Å). In addition to the extensive hydrogen bonding the structure reveals weak CH3···π and π–π interactions (Fig. 3): (i) an almost parallel π-π stacking involving the PHB and THEO aromatic rings (offset of 1.04 Å and distance separation of 3.546 Å between C2/C3/C4/C5/C6/C7 and C8/C9/C10N3/C11/N4 ring centroids); (ii) an offset π–π interaction between C2/C3/C4/C5/C6/C7 and N1/C12/N2/C9/C10/N3/C11/N4/C8 rings (with distance separation and offset for afore mentioned centroids of 4.603 and 3.18 Å respectively); (iii) a CHmethyl···..π interaction (C14···..CPHB ring, with C14 to C2/C3/C4/C5/C6/C7 centroid distance of 3.483 Å), and (iv) a T-shape CHmethyl···π interaction between C13 and CPHB aromatic ring (with shortest distance, C13···C4 of 3.582 (4) Å) (Fig. 3).