organic compounds
Methyl 2-(4-hydroxy-1-methyl-2-oxo-1,2-dihydroquinolin-3-yl)acetate
aSTC "Institute for Single Crystals", National Academy of Sciences of Ukraine, 60 Lenina ave., Kharkiv 61001, Ukraine, and bNational University of Pharmacy, 4 Blyukhera ave., Kharkiv 61002, Ukraine
*Correspondence e-mail: sveta@xray.isc.kharkov.com
In the title compound, C13H13NO4, the bicyclic quinolone fragment and the ester group are approximately orthogonal, making a dihedral angle of 83.3 (2)° and an intramolecular C—H⋯O interaction occurs. In the crystal, intermolecular O—H⋯O hydrogen bonding generates a zigzag chain along the c axis.
Related literature
et al. (2010). For a related structure, see: Ukrainets et al. (2009). For van der Waals radii, see: Zefirov (1997). For reference bond lengths, see: Bürgi & Dunitz (1994).
of 4-hydroxy-2-oxo-1,2-dihydroquinolin-3-acetic acids reveal appreciable biological activity, see: UkrainetsExperimental
Crystal data
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Data collection
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Refinement
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Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell CrysAlis RED; data reduction: CrysAlis RED; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: XP (Siemens, 1998); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S1600536810046453/kp2282sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810046453/kp2282Isup2.hkl
(4-hydroxy-1-methyl-2-oxo-1,2-dihydroquinolin-3-yl)-acetic acid is synthesised using the published method (Ukrainets et al., 2010). Yield 96%; m.p. 452-454 K.
All hydrogen atoms were located from electron density difference maps and were refined in the riding mode approximation with Uiso constrained to be 1.5 times Ueq of the
for the methyl group and 1.2 times Ueq of the for the other atoms. The hydrogen atom of the hydroxyl group was refined in an isotropic mode.Esters of 4-hydroxy-2-oxo-1,2-dihydroquinolin-3-acetic acids reveal appreciable biological activity (Ukrainets et al., 2010). It is interesting that the ethyl ester possesses stronger anti-inflammory activity than methyl ester. On the contrary, the methyl ester has pronounced analgetic activity. In this paper we report the molecular and π interactions between the methyl group at N1-pyridyl atom and C1···C6 aromatic ring [-x, 1-y, 1-z; H···Cg distance (Cg is centre of aromatic ring) is 3.28 Å, C-H···Cg bond angle is 125 °].
of the (4-hydroxy-1-methyl-2-oxo-1,2- dihydroquinolin-3-yl)-acetic acid methyl ester (I) (Fig. 1) with a comparative analysis with previously studied ethyl analogue (II) (Ukrainets et al., 2009). In contrast to II the bicyclic fragment of I is not strictly planar (the C1—N1—C9—C8 torsion angle is -5.8 (2) °). The planar ester group at the C10 atom is orthogonal to the plane of quinoline ring (the C7—C8—C10—C11 torsion angle is 93.9 (1) °) and the C8—C10—C11—O3 torsion angle is -19.7 (2) °. The C9—O1 bond (1.251 (1) Å) is elongated comparing with its mean value (1.210 Å; Bürgi & Dunitz, 1994) owing to the formation of the intermolecular hydrogen bond O2—H2O···O1 (Table 1). The presence of this hydrogen bond determines the orientation of the hydrogen atom of hydroxy group despite of repulsion with one of hydrogen atoms of neighbouring methylene group: the H10a···H2O distance is 2.09 Å [the van der Waals radii sum is 2.34 Å (Zefirov, 1997)]. In the crystal packing the molecules are connected by the O2—H2O···O1 intermolecular hydrogen bond into a zigzag chain along the [0 0 1] direction (Table 1, Fig. 2). Neighbouring chains are connected by the C-H···Esters of 4-hydroxy-2-oxo-1,2-dihydroquinolin-3-acetic acids reveal appreciable
biological activity, see: Ukrainets et al. (2010). For a related structure, see: Ukrainets et al. (2009). For van der Waals radii, see: Zefirov (1997). For reference bond lengths, see: Bürgi & Dunitz (1994).
Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell
CrysAlis RED (Oxford Diffraction, 2005); data reduction: CrysAlis RED (Oxford Diffraction, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: XP (Siemens, 1998); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C13H13NO4 | F(000) = 520 |
Mr = 247.24 | Dx = 1.431 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 9.0792 (6) Å | Cell parameters from 3049 reflections |
b = 11.4904 (6) Å | θ = 2.9–32.1° |
c = 11.4071 (7) Å | µ = 0.11 mm−1 |
β = 105.272 (7)° | T = 293 K |
V = 1148.00 (12) Å3 | Block, colourless |
Z = 4 | 0.20 × 0.10 × 0.10 mm |
Oxford Xcalibur3 diffractometer | 1454 reflections with I > 2σ(I) |
Radiation source: Enhance (Mo) X-ray Source | Rint = 0.031 |
Graphite monochromator | θmax = 30.0°, θmin = 2.9° |
Detector resolution: 16.1827 pixels mm-1 | h = −12→12 |
ω scans | k = −15→16 |
11774 measured reflections | l = −16→16 |
3295 independent reflections |
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)] = 0.035 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.082 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.72 | w = 1/[σ2(Fo2) + (0.044P)2] where P = (Fo2 + 2Fc2)/3 |
3295 reflections | (Δ/σ)max < 0.001 |
169 parameters | Δρmax = 0.14 e Å−3 |
0 restraints | Δρmin = −0.14 e Å−3 |
C13H13NO4 | V = 1148.00 (12) Å3 |
Mr = 247.24 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.0792 (6) Å | µ = 0.11 mm−1 |
b = 11.4904 (6) Å | T = 293 K |
c = 11.4071 (7) Å | 0.20 × 0.10 × 0.10 mm |
β = 105.272 (7)° |
Oxford Xcalibur3 diffractometer | 1454 reflections with I > 2σ(I) |
11774 measured reflections | Rint = 0.031 |
3295 independent reflections |
R[F2 > 2σ(F2)] = 0.035 | 0 restraints |
wR(F2) = 0.082 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.72 | Δρmax = 0.14 e Å−3 |
3295 reflections | Δρmin = −0.14 e Å−3 |
169 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 | ||
N1 | 0.27207 (11) | 0.49052 (8) | 0.49471 (8) | 0.0442 (3) | |
O1 | 0.39749 (11) | 0.33292 (7) | 0.44953 (8) | 0.0582 (3) | |
O2 | 0.26304 (11) | 0.34913 (8) | 0.82386 (8) | 0.0565 (3) | |
H2O | 0.3143 (18) | 0.2811 (15) | 0.8511 (15) | 0.100 (6)* | |
O3 | 0.19057 (12) | 0.11214 (7) | 0.58965 (9) | 0.0613 (3) | |
O4 | 0.41580 (10) | 0.02233 (7) | 0.61834 (8) | 0.0576 (3) | |
C1 | 0.19562 (14) | 0.54717 (10) | 0.56935 (11) | 0.0412 (3) | |
C2 | 0.11931 (15) | 0.65295 (10) | 0.53520 (13) | 0.0538 (4) | |
H2 | 0.1204 | 0.6877 | 0.4618 | 0.065* | |
C3 | 0.04276 (16) | 0.70527 (12) | 0.61044 (14) | 0.0615 (4) | |
H3 | −0.0073 | 0.7755 | 0.5873 | 0.074* | |
C4 | 0.03911 (16) | 0.65520 (11) | 0.71953 (14) | 0.0591 (4) | |
H4 | −0.0132 | 0.6916 | 0.7693 | 0.071* | |
C5 | 0.11239 (14) | 0.55205 (11) | 0.75432 (12) | 0.0500 (3) | |
H5 | 0.1093 | 0.5183 | 0.8277 | 0.060* | |
C6 | 0.19244 (13) | 0.49640 (9) | 0.68027 (10) | 0.0404 (3) | |
C7 | 0.27042 (13) | 0.38819 (10) | 0.71437 (10) | 0.0411 (3) | |
C8 | 0.34114 (14) | 0.33278 (9) | 0.63922 (11) | 0.0416 (3) | |
C9 | 0.33855 (14) | 0.38309 (10) | 0.52337 (11) | 0.0433 (3) | |
C10 | 0.42339 (14) | 0.21863 (10) | 0.66808 (12) | 0.0487 (3) | |
H10B | 0.5113 | 0.2192 | 0.6348 | 0.058* | |
H10A | 0.4607 | 0.2112 | 0.7556 | 0.058* | |
C11 | 0.32703 (16) | 0.11471 (10) | 0.61955 (11) | 0.0439 (3) | |
C12 | 0.33896 (18) | −0.08538 (12) | 0.57708 (14) | 0.0681 (4) | |
H12C | 0.2641 | −0.1004 | 0.6209 | 0.102* | |
H12B | 0.4120 | −0.1477 | 0.5910 | 0.102* | |
H12A | 0.2895 | −0.0800 | 0.4918 | 0.102* | |
C13 | 0.27996 (17) | 0.54417 (12) | 0.38000 (11) | 0.0600 (4) | |
H13C | 0.3199 | 0.6217 | 0.3953 | 0.090* | |
H13B | 0.1795 | 0.5472 | 0.3254 | 0.090* | |
H13A | 0.3456 | 0.4988 | 0.3442 | 0.090* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0566 (7) | 0.0417 (6) | 0.0338 (6) | −0.0103 (5) | 0.0112 (5) | −0.0002 (4) |
O1 | 0.0705 (6) | 0.0588 (6) | 0.0493 (6) | −0.0083 (5) | 0.0230 (5) | −0.0177 (4) |
O2 | 0.0725 (7) | 0.0558 (6) | 0.0474 (6) | 0.0058 (5) | 0.0269 (5) | 0.0123 (5) |
O3 | 0.0581 (6) | 0.0474 (6) | 0.0775 (7) | −0.0025 (5) | 0.0159 (5) | −0.0014 (4) |
O4 | 0.0650 (6) | 0.0387 (5) | 0.0674 (6) | 0.0057 (4) | 0.0144 (5) | −0.0046 (4) |
C1 | 0.0428 (7) | 0.0371 (7) | 0.0410 (7) | −0.0088 (5) | 0.0064 (5) | −0.0028 (5) |
C2 | 0.0580 (9) | 0.0469 (8) | 0.0511 (9) | −0.0068 (7) | 0.0049 (7) | 0.0062 (6) |
C3 | 0.0560 (9) | 0.0444 (8) | 0.0781 (11) | 0.0047 (7) | 0.0071 (8) | −0.0007 (7) |
C4 | 0.0554 (9) | 0.0539 (9) | 0.0672 (10) | 0.0045 (7) | 0.0150 (7) | −0.0136 (7) |
C5 | 0.0506 (8) | 0.0524 (8) | 0.0467 (8) | −0.0019 (6) | 0.0125 (6) | −0.0069 (6) |
C6 | 0.0444 (7) | 0.0354 (6) | 0.0403 (7) | −0.0057 (5) | 0.0090 (5) | −0.0048 (5) |
C7 | 0.0478 (7) | 0.0382 (7) | 0.0375 (7) | −0.0080 (6) | 0.0117 (6) | −0.0002 (5) |
C8 | 0.0464 (7) | 0.0355 (6) | 0.0435 (7) | −0.0070 (5) | 0.0127 (6) | −0.0027 (5) |
C9 | 0.0468 (7) | 0.0417 (7) | 0.0423 (8) | −0.0117 (6) | 0.0131 (6) | −0.0099 (5) |
C10 | 0.0529 (8) | 0.0414 (7) | 0.0537 (8) | 0.0001 (6) | 0.0174 (6) | −0.0016 (6) |
C11 | 0.0577 (9) | 0.0385 (7) | 0.0377 (7) | 0.0003 (7) | 0.0164 (6) | 0.0019 (5) |
C12 | 0.0916 (11) | 0.0384 (8) | 0.0681 (10) | 0.0022 (7) | 0.0100 (8) | −0.0086 (6) |
C13 | 0.0731 (10) | 0.0644 (9) | 0.0426 (8) | −0.0146 (7) | 0.0152 (7) | 0.0062 (6) |
N1—C9 | 1.3751 (15) | C4—H4 | 0.9300 |
N1—C1 | 1.3936 (15) | C5—C6 | 1.4049 (16) |
N1—C13 | 1.4652 (15) | C5—H5 | 0.9300 |
O1—C9 | 1.2512 (14) | C6—C7 | 1.4330 (16) |
O2—C7 | 1.3454 (14) | C7—C8 | 1.3574 (16) |
O2—H2O | 0.921 (17) | C8—C9 | 1.4370 (17) |
O3—C11 | 1.1957 (14) | C8—C10 | 1.5023 (15) |
O4—C11 | 1.3351 (14) | C10—C11 | 1.4975 (17) |
O4—C12 | 1.4378 (15) | C10—H10B | 0.9700 |
C1—C6 | 1.4005 (16) | C10—H10A | 0.9700 |
C1—C2 | 1.4025 (17) | C12—H12C | 0.9600 |
C2—C3 | 1.3766 (19) | C12—H12B | 0.9600 |
C2—H2 | 0.9300 | C12—H12A | 0.9600 |
C3—C4 | 1.379 (2) | C13—H13C | 0.9600 |
C3—H3 | 0.9300 | C13—H13B | 0.9600 |
C4—C5 | 1.3660 (17) | C13—H13A | 0.9600 |
C9—N1—C1 | 122.15 (10) | C7—C8—C10 | 124.17 (11) |
C9—N1—C13 | 117.93 (11) | C9—C8—C10 | 116.07 (11) |
C1—N1—C13 | 119.90 (11) | O1—C9—N1 | 119.49 (11) |
C7—O2—H2O | 116.9 (10) | O1—C9—C8 | 121.83 (12) |
C11—O4—C12 | 116.46 (10) | N1—C9—C8 | 118.66 (11) |
N1—C1—C6 | 119.31 (11) | C11—C10—C8 | 114.01 (10) |
N1—C1—C2 | 121.62 (11) | C11—C10—H10B | 108.8 |
C6—C1—C2 | 119.06 (12) | C8—C10—H10B | 108.8 |
C3—C2—C1 | 119.92 (13) | C11—C10—H10A | 108.8 |
C3—C2—H2 | 120.0 | C8—C10—H10A | 108.8 |
C1—C2—H2 | 120.0 | H10B—C10—H10A | 107.6 |
C2—C3—C4 | 121.09 (13) | O3—C11—O4 | 124.09 (11) |
C2—C3—H3 | 119.5 | O3—C11—C10 | 125.86 (11) |
C4—C3—H3 | 119.5 | O4—C11—C10 | 110.01 (11) |
C5—C4—C3 | 119.90 (13) | O4—C12—H12C | 109.5 |
C5—C4—H4 | 120.1 | O4—C12—H12B | 109.5 |
C3—C4—H4 | 120.1 | H12C—C12—H12B | 109.5 |
C4—C5—C6 | 120.65 (13) | O4—C12—H12A | 109.5 |
C4—C5—H5 | 119.7 | H12C—C12—H12A | 109.5 |
C6—C5—H5 | 119.7 | H12B—C12—H12A | 109.5 |
C1—C6—C5 | 119.38 (11) | N1—C13—H13C | 109.5 |
C1—C6—C7 | 118.71 (11) | N1—C13—H13B | 109.5 |
C5—C6—C7 | 121.91 (11) | H13C—C13—H13B | 109.5 |
O2—C7—C8 | 125.26 (11) | N1—C13—H13A | 109.5 |
O2—C7—C6 | 113.55 (10) | H13C—C13—H13A | 109.5 |
C8—C7—C6 | 121.18 (11) | H13B—C13—H13A | 109.5 |
C7—C8—C9 | 119.75 (11) | ||
C9—N1—C1—C6 | 3.30 (16) | O2—C7—C8—C9 | 178.97 (10) |
C13—N1—C1—C6 | −178.30 (10) | C6—C7—C8—C9 | 0.14 (17) |
C9—N1—C1—C2 | −175.55 (11) | O2—C7—C8—C10 | −0.41 (19) |
C13—N1—C1—C2 | 2.85 (17) | C6—C7—C8—C10 | −179.24 (10) |
N1—C1—C2—C3 | 178.85 (11) | C1—N1—C9—O1 | 175.57 (11) |
C6—C1—C2—C3 | −0.01 (17) | C13—N1—C9—O1 | −2.86 (16) |
C1—C2—C3—C4 | −0.2 (2) | C1—N1—C9—C8 | −5.80 (16) |
C2—C3—C4—C5 | 0.0 (2) | C13—N1—C9—C8 | 175.77 (11) |
C3—C4—C5—C6 | 0.3 (2) | C7—C8—C9—O1 | −177.38 (11) |
N1—C1—C6—C5 | −178.52 (11) | C10—C8—C9—O1 | 2.05 (17) |
C2—C1—C6—C5 | 0.36 (16) | C7—C8—C9—N1 | 4.03 (17) |
N1—C1—C6—C7 | 0.99 (15) | C10—C8—C9—N1 | −176.54 (10) |
C2—C1—C6—C7 | 179.87 (11) | C7—C8—C10—C11 | 93.90 (14) |
C4—C5—C6—C1 | −0.53 (18) | C9—C8—C10—C11 | −85.50 (13) |
C4—C5—C6—C7 | 179.98 (11) | C12—O4—C11—O3 | 0.54 (18) |
C1—C6—C7—O2 | 178.39 (10) | C12—O4—C11—C10 | 178.27 (11) |
C5—C6—C7—O2 | −2.12 (16) | C8—C10—C11—O3 | −19.67 (18) |
C1—C6—C7—C8 | −2.65 (16) | C8—C10—C11—O4 | 162.65 (10) |
C5—C6—C7—C8 | 176.84 (12) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2O···O1i | 0.921 (17) | 1.760 (17) | 2.6456 (12) | 160.2 (15) |
C10—H10A···O1i | 0.97 | 2.48 | 3.3335 (16) | 147 |
C5—H5···O2 | 0.93 | 2.40 | 2.7138 (16) | 100 |
Symmetry code: (i) x, −y+1/2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C13H13NO4 |
Mr | 247.24 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 9.0792 (6), 11.4904 (6), 11.4071 (7) |
β (°) | 105.272 (7) |
V (Å3) | 1148.00 (12) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.20 × 0.10 × 0.10 |
Data collection | |
Diffractometer | Oxford Xcalibur3 |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11774, 3295, 1454 |
Rint | 0.031 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.082, 0.72 |
No. of reflections | 3295 |
No. of parameters | 169 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.14, −0.14 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2005), CrysAlis RED (Oxford Diffraction, 2005), SHELXTL (Sheldrick, 2008), XP (Siemens, 1998).
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2O···O1i | 0.921 (17) | 1.760 (17) | 2.6456 (12) | 160.2 (15) |
C10—H10A···O1i | 0.97 | 2.48 | 3.3335 (16) | 146.8 |
Symmetry code: (i) x, −y+1/2, z+1/2. |
References
Bürgi, H.-B. & Dunitz, J. D. (1994). Structure Correlation, Vol. 2, pp. 767–784. Weinheim: VCH. Google Scholar
Oxford Diffraction (2005). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Siemens (1998). XP. Siemens Analytical X-ray Division Inc., Karlsruhe, Germany. Google Scholar
Ukrainets, I. V., Mospanova, E. V., Davidenko, A. A., Tkach, A. A. & Gorokhova, O. V. (2010). Khim. Geterotsikl. Soedin. pp. 1173–1184. Google Scholar
Ukrainets, I. V., Shishkina, S. V., Shishkin, O. V., Davidenko, A. A. & Tkach, A. A. (2009). Acta Cryst. E65, o968. Web of Science CSD CrossRef IUCr Journals Google Scholar
Zefirov, Yu. V. (1997). Kristallografiya, 42, 936–958. CAS Google Scholar
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Esters of 4-hydroxy-2-oxo-1,2-dihydroquinolin-3-acetic acids reveal appreciable biological activity (Ukrainets et al., 2010). It is interesting that the ethyl ester possesses stronger anti-inflammory activity than methyl ester. On the contrary, the methyl ester has pronounced analgetic activity. In this paper we report the molecular and crystal structure of the (4-hydroxy-1-methyl-2-oxo-1,2- dihydroquinolin-3-yl)-acetic acid methyl ester (I) (Fig. 1) with a comparative analysis with previously studied ethyl analogue (II) (Ukrainets et al., 2009). In contrast to II the bicyclic fragment of I is not strictly planar (the C1—N1—C9—C8 torsion angle is -5.8 (2) °). The planar ester group at the C10 atom is orthogonal to the plane of quinoline ring (the C7—C8—C10—C11 torsion angle is 93.9 (1) °) and the C8—C10—C11—O3 torsion angle is -19.7 (2) °. The C9—O1 bond (1.251 (1) Å) is elongated comparing with its mean value (1.210 Å; Bürgi & Dunitz, 1994) owing to the formation of the intermolecular hydrogen bond O2—H2O···O1 (Table 1). The presence of this hydrogen bond determines the orientation of the hydrogen atom of hydroxy group despite of repulsion with one of hydrogen atoms of neighbouring methylene group: the H10a···H2O distance is 2.09 Å [the van der Waals radii sum is 2.34 Å (Zefirov, 1997)]. In the crystal packing the molecules are connected by the O2—H2O···O1 intermolecular hydrogen bond into a zigzag chain along the [0 0 1] direction (Table 1, Fig. 2). Neighbouring chains are connected by the C-H···π interactions between the methyl group at N1-pyridyl atom and C1···C6 aromatic ring [-x, 1-y, 1-z; H···Cg distance (Cg is centre of aromatic ring) is 3.28 Å, C-H···Cg bond angle is 125 °].