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Acta Crystallogr Sect E Struct Rep Online. 2010 September 1; 66(Pt 9): o2297–o2298.
Published online 2010 August 11. doi:  10.1107/S1600536810031703
PMCID: PMC3008143

Nifedipine–pyrazine (2/1)

Abstract

In the title compound, 2C17H18N2O6·C4H4N2 [systematic name: 3,5-dimethyl 2,6-dimethyl-4-(2-nitro­phen­yl)-1,4-di­hydro­pyridine-3,5-dicarboxyl­ate–pyrazine (2/1)], the complete pyrazine molecule is generated by crystallographic inversion symmetry. The center of the pyrazine ring lies on an inversion center. The nifedipine mol­ecules are linked into chains along the c axis through N—H(...)O hydrogen bonds, while the pyrazine mol­ecules are organized in the structure through van der Waals inter­actions.

Related literature

Co-crystalline materials are of pharmaceutical inter­est due to their ability to alter the physicochemical properties of active pharmaceutical ingredients (APIs) (Schultheiss et al., 2009 [triangle]) and provide drug repositioning or life-cycle management (Trask, 2007 [triangle]). The corresponding crystal structure of nifedipine has been reported (Triggle et al., 2003 [triangle]) and it also forms chains through N—H(...)O hydrogen bonds. Other crystalline forms also exist: polymorphs (Burger et al., 1996 [triangle]) solvates/hydrates (Caira et al., 2003 [triangle]) and a metal complex (Bontchev et al., 2003 [triangle]), as well as a non-crystalline, amorphous phase (Miyazaki et al., 2007 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2297-scheme1.jpg

Experimental

Crystal data

  • C19H20N3O6
  • M r = 386.38
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2297-efi1.jpg
  • a = 13.6278 (14) Å
  • b = 9.1594 (9) Å
  • c = 14.4432 (14) Å
  • β = 94.841 (4)°
  • V = 1796.4 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.11 mm−1
  • T = 120 K
  • 0.24 × 0.18 × 0.10 mm

Data collection

  • Bruker APEXII CCD diffractometer
  • 27572 measured reflections
  • 6070 independent reflections
  • 4916 reflections with I > 2σ(I)
  • R int = 0.036

Refinement

  • R[F 2 > 2σ(F 2)] = 0.043
  • wR(F 2) = 0.125
  • S = 1.07
  • 6070 reflections
  • 261 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.48 e Å−3
  • Δρmin = −0.24 e Å−3

Data collection: APEX2 (Bruker, 2007 [triangle]); cell refinement: SAINT (Bruker, 2007 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: PLATON (Spek, 2009 [triangle]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 [triangle]), PLATON and Mercury (Macrae et al., 2006 [triangle]).

Table 1
Selected torsion angles (°)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810031703/kj2152sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810031703/kj2152Isup2.hkl

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

Acknowledgments

We would like to thank Dr John Desper (Kansas State Univeristy) for the data collection and structure solution. We also thank Mr Eyal Barash and Dr Richard McClurg for their careful review of this manuscript.

supplementary crystallographic information

Comment

Designing, preparing, and characterizing cocrystalline materials is a rapidly growing area of research, especially in the area of pharmaceutics, due to their ability to alter the physicochemical properties of active pharmaceutical ingredients (APIs) (Schultheiss et al., 2009) and provide drug repositioning or life-cycle management (Trask, 2007). Cocrystals are multi-component crystals where the individual, neutral molecules are typically held together through hydrogen-bonding. Nifedipine (1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl) -3,5-pyridine dicarboxylic acid dimethyl ester),a calcium-channel blocker, is known to exist in a variety of crystalline forms: polymorphs (Burger et al., 1996), solvates/hydrates (Caira et al., 2003), and a metal complex (Bontchev et al., 2003), as well as a non-crystalline, amorphous phase (Miyazaki et al., 2007). Suprisingly, examples of nifedipine cocrystals have yet to be published in the open literature, and thus we report here the 2:1 cocrystal of nifedipine and pyrazine.

A view of the asymmetric unit of the title compound and its numbering scheme are displayed in Fig. 1. The material crystallizes in a 2:1 (nifedipine:pyrazine) stoichiometric ratio, although the asymmetric unit contains the components in a 1:0.5 ratio, because the center of the pyrazine ring resides on an inversion center. It should also be noted that the nitro-substituted phenyl ring is relatively orthogonal ("axial") to the dihydropyridine ring (Table 1) which is displayed in Fig. 1. Nonetheless, the nifedipine molecules are linked into linear, one-dimensional chains with a graph set notation of C(6) through N—H···O hydrogen bonds from the N—H moiety to a carbonyl moiety, Table 2. The hydrogen bonds are running along the crystallographic c axis. Interestingly, the pyrazine molecules are not participating in hydrogen bonding with nifedipine, but are organized in between nifedipine rows through multiple van der Waals interactions (Fig. 2). Upon extending the structure into three-dimensions, the organization of the pyrazine molecules within the crystal structure are clearly shown. The pyrazine molecules are not only between one-dimensional rows of nifedipine, but also 'sandwiched' between methyl-ester groups from neighboring nifedipine molecules.

Experimental

The title compound was prepared by adding solid nifedipine to a nearly saturated solution of pyrazine in methanol and allowed to stir for ~24 h at ambient temperature before filtering. Crystals of suitable size for single-crystal analysis were obtained directly from the experiment.

Refinement

The amino H-atom was located in a difference Fourier map. All other H-atoms were positioned geometrically and allowed to ride on their parent atoms with U(H) set to 1.5Ueq(C) for methyl and 1.2Ueq(C) for all other carbon atoms.

Figures

Fig. 1.
The asymmetric unit of the title compound, with the atom labeling scheme and 50% probability displacement ellipsoids.
Fig. 2.
View down the b axis displaying the hydrogen bonding (black-dashed lines) between nifedipine molecules. The pyrazine molecules (ball-and-stick mode) are positioned between the one-dimensional nifedipine rows (right). The direction of the a axis is the ...

Crystal data

C19H20N3O6F(000) = 812
Mr = 386.38Dx = 1.429 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 9767 reflections
a = 13.6278 (14) Åθ = 2.6–31.7°
b = 9.1594 (9) ŵ = 0.11 mm1
c = 14.4432 (14) ÅT = 120 K
β = 94.841 (4)°Prism, colourless
V = 1796.4 (3) Å30.24 × 0.18 × 0.10 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer4916 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.036
graphiteθmax = 31.8°, θmin = 2.6°
[var phi] and ω scansh = −20→19
27572 measured reflectionsk = −13→13
6070 independent reflectionsl = −17→21

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.125H atoms treated by a mixture of independent and constrained refinement
S = 1.07w = 1/[σ2(Fo2) + (0.070P)2 + 0.250P] where P = (Fo2 + 2Fc2)/3
6070 reflections(Δ/σ)max < 0.001
261 parametersΔρmax = 0.48 e Å3
0 restraintsΔρmin = −0.24 e Å3

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
N110.91012 (7)0.66064 (10)0.58015 (6)0.01904 (17)
H110.9275 (12)0.6672 (17)0.6420 (12)0.033 (4)*
C120.96337 (7)0.73800 (11)0.52067 (6)0.01680 (18)
C130.92963 (7)0.74418 (11)0.42914 (6)0.01588 (17)
C140.82937 (7)0.68380 (10)0.39640 (6)0.01536 (17)
H140.83230.64310.33240.018*
C150.80215 (7)0.56174 (10)0.46039 (6)0.01635 (17)
C160.83786 (7)0.56204 (11)0.55095 (7)0.01793 (18)
C221.05495 (8)0.80615 (12)0.56668 (7)0.0214 (2)
H22A1.05590.91040.55150.032*
H22B1.11290.75860.54440.032*
H22C1.05580.79400.63420.032*
C230.98313 (7)0.80823 (11)0.35653 (7)0.01736 (18)
O231.06719 (5)0.87616 (9)0.38444 (5)0.02116 (16)
O240.95391 (6)0.80104 (11)0.27468 (5)0.0315 (2)
C250.73593 (7)0.44528 (11)0.42414 (7)0.01813 (18)
O250.71443 (6)0.45992 (8)0.33133 (5)0.02199 (16)
O260.70447 (6)0.34517 (9)0.46697 (6)0.02589 (17)
C260.80877 (9)0.46176 (12)0.62596 (7)0.0237 (2)
H26A0.73730.46600.62910.036*
H26B0.84180.49210.68580.036*
H26C0.82820.36160.61210.036*
C271.11954 (9)0.93700 (14)0.31148 (8)0.0264 (2)
H27A1.18180.97890.33800.040*
H27B1.07951.01360.27950.040*
H27C1.13300.86010.26710.040*
C280.65577 (9)0.34450 (13)0.28780 (8)0.0276 (2)
H28A0.64010.36760.22190.041*
H28B0.59460.33470.31840.041*
H28C0.69260.25260.29340.041*
C310.75049 (7)0.80317 (10)0.39303 (6)0.01571 (17)
C320.67448 (7)0.82130 (11)0.32317 (7)0.01755 (18)
N320.66655 (7)0.73025 (10)0.23900 (6)0.01976 (17)
O320.73861 (6)0.71650 (9)0.19529 (5)0.02539 (17)
O330.58615 (6)0.67540 (9)0.21593 (6)0.02713 (18)
C330.60043 (8)0.92431 (12)0.32730 (7)0.0219 (2)
H330.54970.93200.27820.026*
C340.60109 (8)1.01542 (12)0.40326 (8)0.0239 (2)
H340.55121.08720.40680.029*
C350.67529 (8)1.00121 (12)0.47455 (7)0.0227 (2)
H350.67631.06340.52730.027*
C360.74769 (8)0.89694 (11)0.46907 (7)0.01926 (19)
H360.79750.88860.51890.023*
N410.45265 (8)0.46068 (12)0.41368 (7)0.0302 (2)
C420.45577 (9)0.37242 (13)0.48684 (9)0.0289 (2)
H420.42480.27960.48050.035*
C430.50253 (9)0.41122 (14)0.57190 (8)0.0297 (2)
H430.50270.34390.62200.036*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N110.0221 (4)0.0250 (4)0.0100 (3)−0.0011 (3)0.0008 (3)0.0011 (3)
C120.0176 (4)0.0209 (4)0.0119 (4)0.0010 (3)0.0011 (3)−0.0001 (3)
C130.0159 (4)0.0201 (4)0.0116 (4)−0.0002 (3)0.0012 (3)0.0004 (3)
C140.0169 (4)0.0183 (4)0.0109 (4)−0.0003 (3)0.0015 (3)−0.0002 (3)
C150.0170 (4)0.0175 (4)0.0147 (4)0.0003 (3)0.0025 (3)0.0005 (3)
C160.0199 (4)0.0197 (4)0.0145 (4)0.0015 (3)0.0032 (3)0.0013 (3)
C220.0200 (5)0.0293 (5)0.0143 (4)−0.0021 (4)−0.0014 (3)−0.0011 (4)
C230.0174 (4)0.0215 (4)0.0132 (4)0.0005 (3)0.0014 (3)−0.0002 (3)
O230.0211 (3)0.0285 (4)0.0141 (3)−0.0065 (3)0.0031 (3)−0.0004 (3)
O240.0279 (4)0.0550 (6)0.0111 (3)−0.0138 (4)−0.0004 (3)0.0043 (3)
C250.0182 (4)0.0187 (4)0.0178 (4)0.0024 (3)0.0029 (3)−0.0004 (3)
O250.0246 (4)0.0240 (4)0.0170 (3)−0.0059 (3)−0.0004 (3)−0.0019 (3)
O260.0308 (4)0.0224 (4)0.0247 (4)−0.0055 (3)0.0037 (3)0.0025 (3)
C260.0300 (5)0.0242 (5)0.0173 (4)−0.0007 (4)0.0043 (4)0.0057 (4)
C270.0270 (5)0.0335 (6)0.0196 (5)−0.0097 (4)0.0066 (4)0.0014 (4)
C280.0273 (5)0.0295 (5)0.0256 (5)−0.0089 (4)0.0003 (4)−0.0067 (4)
C310.0166 (4)0.0175 (4)0.0131 (4)−0.0010 (3)0.0018 (3)0.0015 (3)
C320.0188 (4)0.0202 (4)0.0135 (4)−0.0018 (3)0.0001 (3)0.0002 (3)
N320.0221 (4)0.0224 (4)0.0142 (4)0.0003 (3)−0.0022 (3)0.0010 (3)
O320.0270 (4)0.0339 (4)0.0155 (3)0.0015 (3)0.0033 (3)−0.0017 (3)
O330.0249 (4)0.0304 (4)0.0245 (4)−0.0054 (3)−0.0067 (3)−0.0025 (3)
C330.0204 (5)0.0244 (5)0.0204 (5)0.0022 (4)−0.0012 (3)0.0022 (4)
C340.0252 (5)0.0227 (5)0.0237 (5)0.0054 (4)0.0014 (4)0.0010 (4)
C350.0276 (5)0.0208 (4)0.0197 (5)0.0031 (4)0.0017 (4)−0.0029 (4)
C360.0223 (5)0.0204 (4)0.0149 (4)0.0009 (3)0.0002 (3)−0.0008 (3)
N410.0291 (5)0.0373 (5)0.0247 (5)−0.0013 (4)0.0058 (4)−0.0037 (4)
C420.0283 (6)0.0271 (5)0.0327 (6)−0.0038 (4)0.0101 (4)−0.0035 (5)
C430.0313 (6)0.0325 (6)0.0264 (5)0.0000 (5)0.0093 (4)0.0046 (5)

Geometric parameters (Å, °)

N11—C121.3682 (13)C27—H27A0.9800
N11—C161.3759 (13)C27—H27B0.9800
N11—H110.906 (17)C27—H27C0.9800
C12—C131.3636 (13)C28—H28A0.9800
C12—C221.4996 (14)C28—H28B0.9800
C13—C231.4507 (13)C28—H28C0.9800
C13—C141.5125 (13)C31—C321.3937 (13)
C14—C151.5165 (13)C31—C361.3973 (13)
C14—C311.5311 (13)C32—C331.3865 (14)
C14—H141.0000C32—N321.4706 (13)
C15—C161.3566 (13)N32—O321.2180 (12)
C15—C251.4651 (14)N32—O331.2257 (12)
C16—C261.4989 (14)C33—C341.3778 (15)
C22—H22A0.9800C33—H330.9500
C22—H22B0.9800C34—C351.3871 (15)
C22—H22C0.9800C34—H340.9500
C23—O241.2170 (12)C35—C361.3802 (14)
C23—O231.3357 (12)C35—H350.9500
O23—C271.4342 (12)C36—H360.9500
C25—O261.2050 (12)N41—C421.3282 (17)
C25—O251.3544 (12)N41—C43i1.3311 (17)
O25—C281.4377 (13)C42—C431.3819 (18)
C26—H26A0.9800C42—H420.9500
C26—H26B0.9800C43—N41i1.3311 (17)
C26—H26C0.9800C43—H430.9500
C12—N11—C16123.46 (8)O23—C27—H27B109.5
C12—N11—H11118.4 (10)H27A—C27—H27B109.5
C16—N11—H11117.8 (10)O23—C27—H27C109.5
C13—C12—N11118.48 (9)H27A—C27—H27C109.5
C13—C12—C22127.75 (9)H27B—C27—H27C109.5
N11—C12—C22113.77 (8)O25—C28—H28A109.5
C12—C13—C23124.66 (9)O25—C28—H28B109.5
C12—C13—C14120.65 (8)H28A—C28—H28B109.5
C23—C13—C14114.68 (8)O25—C28—H28C109.5
C13—C14—C15109.88 (8)H28A—C28—H28C109.5
C13—C14—C31111.23 (8)H28B—C28—H28C109.5
C15—C14—C31109.79 (8)C32—C31—C36115.33 (9)
C13—C14—H14108.6C32—C31—C14125.80 (8)
C15—C14—H14108.6C36—C31—C14118.66 (8)
C31—C14—H14108.6C33—C32—C31123.31 (9)
C16—C15—C25120.41 (9)C33—C32—N32114.74 (9)
C16—C15—C14119.99 (9)C31—C32—N32121.95 (9)
C25—C15—C14119.60 (8)O32—N32—O33123.91 (9)
C15—C16—N11119.08 (9)O32—N32—C32118.74 (9)
C15—C16—C26126.89 (9)O33—N32—C32117.32 (9)
N11—C16—C26114.01 (9)C34—C33—C32119.38 (10)
C12—C22—H22A109.5C34—C33—H33120.3
C12—C22—H22B109.5C32—C33—H33120.3
H22A—C22—H22B109.5C33—C34—C35119.32 (10)
C12—C22—H22C109.5C33—C34—H34120.3
H22A—C22—H22C109.5C35—C34—H34120.3
H22B—C22—H22C109.5C36—C35—C34120.14 (10)
O24—C23—O23121.36 (9)C36—C35—H35119.9
O24—C23—C13122.49 (9)C34—C35—H35119.9
O23—C23—C13116.15 (8)C35—C36—C31122.51 (9)
C23—O23—C27115.24 (8)C35—C36—H36118.7
O26—C25—O25121.79 (9)C31—C36—H36118.7
O26—C25—C15127.27 (9)C42—N41—C43i115.38 (11)
O25—C25—C15110.91 (8)C42—N41—C42ii106.16 (7)
C25—O25—C28115.21 (8)C43i—N41—C42ii137.11 (8)
C16—C26—H26A109.5N41—C42—C43122.15 (11)
C16—C26—H26B109.5N41—C42—H42118.9
H26A—C26—H26B109.5C43—C42—H42118.9
C16—C26—H26C109.5N41i—C43—C42122.46 (11)
H26A—C26—H26C109.5N41i—C43—H43118.8
H26B—C26—H26C109.5C42—C43—H43118.8
O23—C27—H27A109.5
C16—N11—C12—C1315.45 (15)C14—C15—C25—O26−176.60 (10)
C16—N11—C12—C22−164.07 (9)C16—C15—C25—O25−175.78 (9)
N11—C12—C13—C23−173.05 (9)C14—C15—C25—O255.23 (12)
C22—C12—C13—C236.40 (17)O26—C25—O25—C28−2.79 (14)
N11—C12—C13—C147.81 (14)C15—C25—O25—C28175.50 (8)
C22—C12—C13—C14−172.75 (9)C13—C14—C31—C32138.67 (9)
C12—C13—C14—C15−27.91 (12)C15—C14—C31—C32−99.50 (11)
C23—C13—C14—C15152.87 (8)C13—C14—C31—C36−46.76 (11)
C12—C13—C14—C3193.88 (10)C15—C14—C31—C3675.07 (11)
C23—C13—C14—C31−85.35 (10)C36—C31—C32—C33−0.04 (14)
C13—C14—C15—C1628.86 (12)C14—C31—C32—C33174.69 (9)
C31—C14—C15—C16−93.78 (10)C36—C31—C32—N32−179.46 (9)
C13—C14—C15—C25−152.15 (8)C14—C31—C32—N32−4.73 (15)
C31—C14—C15—C2585.21 (10)C33—C32—N32—O32130.11 (10)
C25—C15—C16—N11171.13 (9)C31—C32—N32—O32−50.42 (13)
C14—C15—C16—N11−9.89 (14)C33—C32—N32—O33−48.13 (12)
C25—C15—C16—C26−7.30 (15)C31—C32—N32—O33131.33 (10)
C14—C15—C16—C26171.68 (9)C31—C32—C33—C340.63 (16)
C12—N11—C16—C15−14.39 (15)N32—C32—C33—C34−179.91 (9)
C12—N11—C16—C26164.24 (9)C32—C33—C34—C35−0.67 (16)
C12—C13—C23—O24173.91 (11)C33—C34—C35—C360.14 (17)
C14—C13—C23—O24−6.90 (14)C34—C35—C36—C310.48 (16)
C12—C13—C23—O23−6.01 (15)C32—C31—C36—C35−0.51 (14)
C14—C13—C23—O23173.19 (8)C14—C31—C36—C35−175.64 (9)
O24—C23—O23—C27−0.71 (15)C43i—N41—C42—C43−0.10 (19)
C13—C23—O23—C27179.21 (9)C42ii—N41—C42—C43−169.14 (10)
C16—C15—C25—O262.38 (16)N41—C42—C43—N41i0.1 (2)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y, −z.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N11—H11···O24iii0.906 (17)1.942 (17)2.8444 (12)173.6 (15)

Symmetry codes: (iii) x, −y+3/2, z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: KJ2152).

References

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