Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536810031703/kj2152sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536810031703/kj2152Isup2.hkl |
CCDC reference: 792398
Key indicators
- Single-crystal X-ray study
- T = 120 K
- Mean (C-C) = 0.001 Å
- R factor = 0.043
- wR factor = 0.125
- Data-to-parameter ratio = 23.3
checkCIF/PLATON results
No syntax errors found
Alert level C PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) ..... 1 PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L= 0.600 20 PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L= 0.600 61
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
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.
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.
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.
Cocrystalline materials are of pharmaceutical interest 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). The corresponding crystal structure of nifedipine has been reported (Triggle et al., 2003) and it also forms chains through N—H···O hydrogen bonds. Other crystalline forms also exist: 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).
Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), PLATON (Spek, 2009) and Mercury (Macrae et al., 2006).
C19H20N3O6 | F(000) = 812 |
Mr = 386.38 | Dx = 1.429 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 9767 reflections |
a = 13.6278 (14) Å | θ = 2.6–31.7° |
b = 9.1594 (9) Å | µ = 0.11 mm−1 |
c = 14.4432 (14) Å | T = 120 K |
β = 94.841 (4)° | Prism, colourless |
V = 1796.4 (3) Å3 | 0.24 × 0.18 × 0.10 mm |
Z = 4 |
Bruker APEXII CCD diffractometer | 4916 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.036 |
Graphite monochromator | θmax = 31.8°, θmin = 2.6° |
φ and ω scans | h = −20→19 |
27572 measured reflections | k = −13→13 |
6070 independent reflections | l = −17→21 |
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)] = 0.043 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.125 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | w = 1/[σ2(Fo2) + (0.070P)2 + 0.250P] where P = (Fo2 + 2Fc2)/3 |
6070 reflections | (Δ/σ)max < 0.001 |
261 parameters | Δρmax = 0.48 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
C19H20N3O6 | V = 1796.4 (3) Å3 |
Mr = 386.38 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.6278 (14) Å | µ = 0.11 mm−1 |
b = 9.1594 (9) Å | T = 120 K |
c = 14.4432 (14) Å | 0.24 × 0.18 × 0.10 mm |
β = 94.841 (4)° |
Bruker APEXII CCD diffractometer | 4916 reflections with I > 2σ(I) |
27572 measured reflections | Rint = 0.036 |
6070 independent reflections |
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.125 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.48 e Å−3 |
6070 reflections | Δρmin = −0.24 e Å−3 |
261 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 | ||
N11 | 0.91012 (7) | 0.66064 (10) | 0.58015 (6) | 0.01904 (17) | |
H11 | 0.9275 (12) | 0.6672 (17) | 0.6420 (12) | 0.033 (4)* | |
C12 | 0.96337 (7) | 0.73800 (11) | 0.52067 (6) | 0.01680 (18) | |
C13 | 0.92963 (7) | 0.74418 (11) | 0.42914 (6) | 0.01588 (17) | |
C14 | 0.82937 (7) | 0.68380 (10) | 0.39640 (6) | 0.01536 (17) | |
H14 | 0.8323 | 0.6431 | 0.3324 | 0.018* | |
C15 | 0.80215 (7) | 0.56174 (10) | 0.46039 (6) | 0.01635 (17) | |
C16 | 0.83786 (7) | 0.56204 (11) | 0.55095 (7) | 0.01793 (18) | |
C22 | 1.05495 (8) | 0.80615 (12) | 0.56668 (7) | 0.0214 (2) | |
H22A | 1.0559 | 0.9104 | 0.5515 | 0.032* | |
H22B | 1.1129 | 0.7586 | 0.5444 | 0.032* | |
H22C | 1.0558 | 0.7940 | 0.6342 | 0.032* | |
C23 | 0.98313 (7) | 0.80823 (11) | 0.35653 (7) | 0.01736 (18) | |
O23 | 1.06719 (5) | 0.87616 (9) | 0.38444 (5) | 0.02116 (16) | |
O24 | 0.95391 (6) | 0.80104 (11) | 0.27468 (5) | 0.0315 (2) | |
C25 | 0.73593 (7) | 0.44528 (11) | 0.42414 (7) | 0.01813 (18) | |
O25 | 0.71443 (6) | 0.45992 (8) | 0.33133 (5) | 0.02199 (16) | |
O26 | 0.70447 (6) | 0.34517 (9) | 0.46697 (6) | 0.02589 (17) | |
C26 | 0.80877 (9) | 0.46176 (12) | 0.62596 (7) | 0.0237 (2) | |
H26A | 0.7373 | 0.4660 | 0.6291 | 0.036* | |
H26B | 0.8418 | 0.4921 | 0.6858 | 0.036* | |
H26C | 0.8282 | 0.3616 | 0.6121 | 0.036* | |
C27 | 1.11954 (9) | 0.93700 (14) | 0.31148 (8) | 0.0264 (2) | |
H27A | 1.1818 | 0.9789 | 0.3380 | 0.040* | |
H27B | 1.0795 | 1.0136 | 0.2795 | 0.040* | |
H27C | 1.1330 | 0.8601 | 0.2671 | 0.040* | |
C28 | 0.65577 (9) | 0.34450 (13) | 0.28780 (8) | 0.0276 (2) | |
H28A | 0.6401 | 0.3676 | 0.2219 | 0.041* | |
H28B | 0.5946 | 0.3347 | 0.3184 | 0.041* | |
H28C | 0.6926 | 0.2526 | 0.2934 | 0.041* | |
C31 | 0.75049 (7) | 0.80317 (10) | 0.39303 (6) | 0.01571 (17) | |
C32 | 0.67448 (7) | 0.82130 (11) | 0.32317 (7) | 0.01755 (18) | |
N32 | 0.66655 (7) | 0.73025 (10) | 0.23900 (6) | 0.01976 (17) | |
O32 | 0.73861 (6) | 0.71650 (9) | 0.19529 (5) | 0.02539 (17) | |
O33 | 0.58615 (6) | 0.67540 (9) | 0.21593 (6) | 0.02713 (18) | |
C33 | 0.60043 (8) | 0.92431 (12) | 0.32730 (7) | 0.0219 (2) | |
H33 | 0.5497 | 0.9320 | 0.2782 | 0.026* | |
C34 | 0.60109 (8) | 1.01542 (12) | 0.40326 (8) | 0.0239 (2) | |
H34 | 0.5512 | 1.0872 | 0.4068 | 0.029* | |
C35 | 0.67529 (8) | 1.00121 (12) | 0.47455 (7) | 0.0227 (2) | |
H35 | 0.6763 | 1.0634 | 0.5273 | 0.027* | |
C36 | 0.74769 (8) | 0.89694 (11) | 0.46907 (7) | 0.01926 (19) | |
H36 | 0.7975 | 0.8886 | 0.5189 | 0.023* | |
N41 | 0.45265 (8) | 0.46068 (12) | 0.41368 (7) | 0.0302 (2) | |
C42 | 0.45577 (9) | 0.37242 (13) | 0.48684 (9) | 0.0289 (2) | |
H42 | 0.4248 | 0.2796 | 0.4805 | 0.035* | |
C43 | 0.50253 (9) | 0.41122 (14) | 0.57190 (8) | 0.0297 (2) | |
H43 | 0.5027 | 0.3439 | 0.6220 | 0.036* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N11 | 0.0221 (4) | 0.0250 (4) | 0.0100 (3) | −0.0011 (3) | 0.0008 (3) | 0.0011 (3) |
C12 | 0.0176 (4) | 0.0209 (4) | 0.0119 (4) | 0.0010 (3) | 0.0011 (3) | −0.0001 (3) |
C13 | 0.0159 (4) | 0.0201 (4) | 0.0116 (4) | −0.0002 (3) | 0.0012 (3) | 0.0004 (3) |
C14 | 0.0169 (4) | 0.0183 (4) | 0.0109 (4) | −0.0003 (3) | 0.0015 (3) | −0.0002 (3) |
C15 | 0.0170 (4) | 0.0175 (4) | 0.0147 (4) | 0.0003 (3) | 0.0025 (3) | 0.0005 (3) |
C16 | 0.0199 (4) | 0.0197 (4) | 0.0145 (4) | 0.0015 (3) | 0.0032 (3) | 0.0013 (3) |
C22 | 0.0200 (5) | 0.0293 (5) | 0.0143 (4) | −0.0021 (4) | −0.0014 (3) | −0.0011 (4) |
C23 | 0.0174 (4) | 0.0215 (4) | 0.0132 (4) | 0.0005 (3) | 0.0014 (3) | −0.0002 (3) |
O23 | 0.0211 (3) | 0.0285 (4) | 0.0141 (3) | −0.0065 (3) | 0.0031 (3) | −0.0004 (3) |
O24 | 0.0279 (4) | 0.0550 (6) | 0.0111 (3) | −0.0138 (4) | −0.0004 (3) | 0.0043 (3) |
C25 | 0.0182 (4) | 0.0187 (4) | 0.0178 (4) | 0.0024 (3) | 0.0029 (3) | −0.0004 (3) |
O25 | 0.0246 (4) | 0.0240 (4) | 0.0170 (3) | −0.0059 (3) | −0.0004 (3) | −0.0019 (3) |
O26 | 0.0308 (4) | 0.0224 (4) | 0.0247 (4) | −0.0055 (3) | 0.0037 (3) | 0.0025 (3) |
C26 | 0.0300 (5) | 0.0242 (5) | 0.0173 (4) | −0.0007 (4) | 0.0043 (4) | 0.0057 (4) |
C27 | 0.0270 (5) | 0.0335 (6) | 0.0196 (5) | −0.0097 (4) | 0.0066 (4) | 0.0014 (4) |
C28 | 0.0273 (5) | 0.0295 (5) | 0.0256 (5) | −0.0089 (4) | 0.0003 (4) | −0.0067 (4) |
C31 | 0.0166 (4) | 0.0175 (4) | 0.0131 (4) | −0.0010 (3) | 0.0018 (3) | 0.0015 (3) |
C32 | 0.0188 (4) | 0.0202 (4) | 0.0135 (4) | −0.0018 (3) | 0.0001 (3) | 0.0002 (3) |
N32 | 0.0221 (4) | 0.0224 (4) | 0.0142 (4) | 0.0003 (3) | −0.0022 (3) | 0.0010 (3) |
O32 | 0.0270 (4) | 0.0339 (4) | 0.0155 (3) | 0.0015 (3) | 0.0033 (3) | −0.0017 (3) |
O33 | 0.0249 (4) | 0.0304 (4) | 0.0245 (4) | −0.0054 (3) | −0.0067 (3) | −0.0025 (3) |
C33 | 0.0204 (5) | 0.0244 (5) | 0.0204 (5) | 0.0022 (4) | −0.0012 (3) | 0.0022 (4) |
C34 | 0.0252 (5) | 0.0227 (5) | 0.0237 (5) | 0.0054 (4) | 0.0014 (4) | 0.0010 (4) |
C35 | 0.0276 (5) | 0.0208 (4) | 0.0197 (5) | 0.0031 (4) | 0.0017 (4) | −0.0029 (4) |
C36 | 0.0223 (5) | 0.0204 (4) | 0.0149 (4) | 0.0009 (3) | 0.0002 (3) | −0.0008 (3) |
N41 | 0.0291 (5) | 0.0373 (5) | 0.0247 (5) | −0.0013 (4) | 0.0058 (4) | −0.0037 (4) |
C42 | 0.0283 (6) | 0.0271 (5) | 0.0327 (6) | −0.0038 (4) | 0.0101 (4) | −0.0035 (5) |
C43 | 0.0313 (6) | 0.0325 (6) | 0.0264 (5) | 0.0000 (5) | 0.0093 (4) | 0.0046 (5) |
N11—C12 | 1.3682 (13) | C27—H27A | 0.9800 |
N11—C16 | 1.3759 (13) | C27—H27B | 0.9800 |
N11—H11 | 0.906 (17) | C27—H27C | 0.9800 |
C12—C13 | 1.3636 (13) | C28—H28A | 0.9800 |
C12—C22 | 1.4996 (14) | C28—H28B | 0.9800 |
C13—C23 | 1.4507 (13) | C28—H28C | 0.9800 |
C13—C14 | 1.5125 (13) | C31—C32 | 1.3937 (13) |
C14—C15 | 1.5165 (13) | C31—C36 | 1.3973 (13) |
C14—C31 | 1.5311 (13) | C32—C33 | 1.3865 (14) |
C14—H14 | 1.0000 | C32—N32 | 1.4706 (13) |
C15—C16 | 1.3566 (13) | N32—O32 | 1.2180 (12) |
C15—C25 | 1.4651 (14) | N32—O33 | 1.2257 (12) |
C16—C26 | 1.4989 (14) | C33—C34 | 1.3778 (15) |
C22—H22A | 0.9800 | C33—H33 | 0.9500 |
C22—H22B | 0.9800 | C34—C35 | 1.3871 (15) |
C22—H22C | 0.9800 | C34—H34 | 0.9500 |
C23—O24 | 1.2170 (12) | C35—C36 | 1.3802 (14) |
C23—O23 | 1.3357 (12) | C35—H35 | 0.9500 |
O23—C27 | 1.4342 (12) | C36—H36 | 0.9500 |
C25—O26 | 1.2050 (12) | N41—C42 | 1.3282 (17) |
C25—O25 | 1.3544 (12) | N41—C43i | 1.3311 (17) |
O25—C28 | 1.4377 (13) | C42—C43 | 1.3819 (18) |
C26—H26A | 0.9800 | C42—H42 | 0.9500 |
C26—H26B | 0.9800 | C43—N41i | 1.3311 (17) |
C26—H26C | 0.9800 | C43—H43 | 0.9500 |
C12—N11—C16 | 123.46 (8) | O23—C27—H27B | 109.5 |
C12—N11—H11 | 118.4 (10) | H27A—C27—H27B | 109.5 |
C16—N11—H11 | 117.8 (10) | O23—C27—H27C | 109.5 |
C13—C12—N11 | 118.48 (9) | H27A—C27—H27C | 109.5 |
C13—C12—C22 | 127.75 (9) | H27B—C27—H27C | 109.5 |
N11—C12—C22 | 113.77 (8) | O25—C28—H28A | 109.5 |
C12—C13—C23 | 124.66 (9) | O25—C28—H28B | 109.5 |
C12—C13—C14 | 120.65 (8) | H28A—C28—H28B | 109.5 |
C23—C13—C14 | 114.68 (8) | O25—C28—H28C | 109.5 |
C13—C14—C15 | 109.88 (8) | H28A—C28—H28C | 109.5 |
C13—C14—C31 | 111.23 (8) | H28B—C28—H28C | 109.5 |
C15—C14—C31 | 109.79 (8) | C32—C31—C36 | 115.33 (9) |
C13—C14—H14 | 108.6 | C32—C31—C14 | 125.80 (8) |
C15—C14—H14 | 108.6 | C36—C31—C14 | 118.66 (8) |
C31—C14—H14 | 108.6 | C33—C32—C31 | 123.31 (9) |
C16—C15—C25 | 120.41 (9) | C33—C32—N32 | 114.74 (9) |
C16—C15—C14 | 119.99 (9) | C31—C32—N32 | 121.95 (9) |
C25—C15—C14 | 119.60 (8) | O32—N32—O33 | 123.91 (9) |
C15—C16—N11 | 119.08 (9) | O32—N32—C32 | 118.74 (9) |
C15—C16—C26 | 126.89 (9) | O33—N32—C32 | 117.32 (9) |
N11—C16—C26 | 114.01 (9) | C34—C33—C32 | 119.38 (10) |
C12—C22—H22A | 109.5 | C34—C33—H33 | 120.3 |
C12—C22—H22B | 109.5 | C32—C33—H33 | 120.3 |
H22A—C22—H22B | 109.5 | C33—C34—C35 | 119.32 (10) |
C12—C22—H22C | 109.5 | C33—C34—H34 | 120.3 |
H22A—C22—H22C | 109.5 | C35—C34—H34 | 120.3 |
H22B—C22—H22C | 109.5 | C36—C35—C34 | 120.14 (10) |
O24—C23—O23 | 121.36 (9) | C36—C35—H35 | 119.9 |
O24—C23—C13 | 122.49 (9) | C34—C35—H35 | 119.9 |
O23—C23—C13 | 116.15 (8) | C35—C36—C31 | 122.51 (9) |
C23—O23—C27 | 115.24 (8) | C35—C36—H36 | 118.7 |
O26—C25—O25 | 121.79 (9) | C31—C36—H36 | 118.7 |
O26—C25—C15 | 127.27 (9) | C42—N41—C43i | 115.38 (11) |
O25—C25—C15 | 110.91 (8) | C42—N41—C42ii | 106.16 (7) |
C25—O25—C28 | 115.21 (8) | C43i—N41—C42ii | 137.11 (8) |
C16—C26—H26A | 109.5 | N41—C42—C43 | 122.15 (11) |
C16—C26—H26B | 109.5 | N41—C42—H42 | 118.9 |
H26A—C26—H26B | 109.5 | C43—C42—H42 | 118.9 |
C16—C26—H26C | 109.5 | N41i—C43—C42 | 122.46 (11) |
H26A—C26—H26C | 109.5 | N41i—C43—H43 | 118.8 |
H26B—C26—H26C | 109.5 | C42—C43—H43 | 118.8 |
O23—C27—H27A | 109.5 | ||
C16—N11—C12—C13 | 15.45 (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—O25 | 5.23 (12) |
C22—C12—C13—C23 | 6.40 (17) | O26—C25—O25—C28 | −2.79 (14) |
N11—C12—C13—C14 | 7.81 (14) | C15—C25—O25—C28 | 175.50 (8) |
C22—C12—C13—C14 | −172.75 (9) | C13—C14—C31—C32 | 138.67 (9) |
C12—C13—C14—C15 | −27.91 (12) | C15—C14—C31—C32 | −99.50 (11) |
C23—C13—C14—C15 | 152.87 (8) | C13—C14—C31—C36 | −46.76 (11) |
C12—C13—C14—C31 | 93.88 (10) | C15—C14—C31—C36 | 75.07 (11) |
C23—C13—C14—C31 | −85.35 (10) | C36—C31—C32—C33 | −0.04 (14) |
C13—C14—C15—C16 | 28.86 (12) | C14—C31—C32—C33 | 174.69 (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—C25 | 85.21 (10) | C33—C32—N32—O32 | 130.11 (10) |
C25—C15—C16—N11 | 171.13 (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—O33 | 131.33 (10) |
C14—C15—C16—C26 | 171.68 (9) | C31—C32—C33—C34 | 0.63 (16) |
C12—N11—C16—C15 | −14.39 (15) | N32—C32—C33—C34 | −179.91 (9) |
C12—N11—C16—C26 | 164.24 (9) | C32—C33—C34—C35 | −0.67 (16) |
C12—C13—C23—O24 | 173.91 (11) | C33—C34—C35—C36 | 0.14 (17) |
C14—C13—C23—O24 | −6.90 (14) | C34—C35—C36—C31 | 0.48 (16) |
C12—C13—C23—O23 | −6.01 (15) | C32—C31—C36—C35 | −0.51 (14) |
C14—C13—C23—O23 | 173.19 (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—C27 | 179.21 (9) | C42ii—N41—C42—C43 | −169.14 (10) |
C16—C15—C25—O26 | 2.38 (16) | N41—C42—C43—N41i | 0.1 (2) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H11···O24iii | 0.906 (17) | 1.942 (17) | 2.8444 (12) | 173.6 (15) |
Symmetry code: (iii) x, −y+3/2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C19H20N3O6 |
Mr | 386.38 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 120 |
a, b, c (Å) | 13.6278 (14), 9.1594 (9), 14.4432 (14) |
β (°) | 94.841 (4) |
V (Å3) | 1796.4 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.24 × 0.18 × 0.10 |
Data collection | |
Diffractometer | Bruker APEXII CCD |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 27572, 6070, 4916 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.742 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.125, 1.07 |
No. of reflections | 6070 |
No. of parameters | 261 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.48, −0.24 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), PLATON (Spek, 2009) and Mercury (Macrae et al., 2006).
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H11···O24i | 0.906 (17) | 1.942 (17) | 2.8444 (12) | 173.6 (15) |
Symmetry code: (i) x, −y+3/2, z+1/2. |
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.