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Acta Crystallogr Sect E Struct Rep Online. 2010 August 1; 66(Pt 8): o2010–o2011.
Published online 2010 July 14. doi:  10.1107/S1600536810027042
PMCID: PMC3007529

4-Amino­pyridinium 2-hy­droxy­benzoate

Abstract

In the salicylate anion of the title salt, C5H7N2 +·C7H5O3 , an intra­molecular O—H(...)O hydrogen bond generating an S(6) ring motif is observed. In the crystal structure, the cations and anions are linked into a two-dimensional network parallel to the ab plane by N—H(...)O and C—H(...)O hydrogen bonds. The network contains R 2 2(7) and R 1 2(4) ring motifs. Weak π–π inter­actions between the benzene and pyridinium rings [centroid–centroid distance = 3.688 (1) Å] are also observed.

Related literature

For the biological activity of 4-amino­pyridine, see: Schwid et al. (1997 [triangle]). For the crystal structure of 4-amino­pyridine, see: Chao & Schempp (1977 [triangle]); Anderson et al. (2005 [triangle]). For related structures, see: Bhattacharya et al. (1994 [triangle]); Karle et al. (2003 [triangle]); Gellert & Hsu (1988 [triangle]); Hemamalini & Fun (2010 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2010-scheme1.jpg

Experimental

Crystal data

  • C5H7N2 +·C7H5O3
  • M r = 232.24
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2010-efi1.jpg
  • a = 12.5801 (2) Å
  • b = 11.4157 (2) Å
  • c = 15.7560 (3) Å
  • V = 2262.73 (7) Å3
  • Z = 8
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 100 K
  • 0.29 × 0.17 × 0.08 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2009 [triangle]) T min = 0.971, T max = 0.992
  • 15672 measured reflections
  • 3010 independent reflections
  • 2303 reflections with I > 2σ(I)
  • R int = 0.057

Refinement

  • R[F 2 > 2σ(F 2)] = 0.059
  • wR(F 2) = 0.118
  • S = 1.09
  • 3010 reflections
  • 170 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.37 e Å−3
  • Δρmin = −0.26 e Å−3

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

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810027042/ci5130sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810027042/ci5130Isup2.hkl

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

Acknowledgments

HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Aminopyridines are key intermediates for the synthesis of important pharmaceuticals and agrochemicals. Particularly, 4-aminopyridine (fampridine) is used in the treatment of neurological ailments, such as multiple sclerosis (MS), with tests showing that fampridine improves motor function in MS patients (Schwid et al., 1997). The crystal structure of 4-amino pyridine was first reported by Chao and Schempp (1977) and a redetermination was reported by Anderson et al. (2005). Salicylic acid (SA) is a common component in liquid scintillation systems. Salts of salicylic acid are good candidates for dry solid scintillators. Knowledge of these structural data is important to the development of a fundamental understanding of its scintillating properties, and more generally a predictive capability for tailoring materials to achieve desired scintillation properties. The present study has been carried out in order to study the hydrogen bonding patterns present in the crystal structure of 4-aminopyridinium salicylate, (I).

The asymmetric unit of (I) (Fig. 1) contains one 4-aminopyridinium cation and one salicylate anion, indicating that proton transfer occurred during the co-crystallisation experiment. Protonation leads to the widening of C8—N1—C12 angle in the pyridine ring to 120.26 (16)°, compared to 115.25 (13)° in neutal 4-aminopyridine (Anderson et al., 2005). This type of protonation has been observed in various 4-aminopyridine acid complexes (Bhattacharya et al., 1994; Karle et al., 2003). The bond lengths (Allen et al., 1987) and angles are within normal ranges.

In the crystal packing (Fig. 2), the protonated N atom and the hydrogen atom attached to atom C12 are hydrogen-bonded to the carboxylate oxygen atoms (O2 and O3) via N1—H1N1···O3 and C12—H12A···O2 hydrogen bonds, leading to the formation of an R22(7) ring motif (Bernstein et al., 1995). The carboxylate O atoms of the salicylate anion act as acceptors of bifurcated N1—H1N1···O2 and N1—H1N1···O3 hydrogen bonds with the protonated aromatic ring N atom of the 4-aminopyridinium cation, forming a ring with the graph-set notation R21(4). Furthermore, these two motifs are connected via N2—H1N2···O2 and C11—H11A···O3 (Table 1) hydrogen bonds, forming a two-dimensional network parallel to the ab-plane. There is an intramolecular O1—H1O1···O3 hydrogen bond in the salicylate anion, which generates an S(6) ring motif. This motif is also observed in the crystal structures of 2-aminopyridinium salicylate (Gellert & Hsu, 1988) and 2-amino-5-chloropyridinium salicylate (Hemamalini & Fun, 2010). The crystal structure is further stabilized by π–π interactions between the benzene ring at (x, y, z) and pyridinium ring at (3/2-x, 1/2+y, z) with a centroid-to-centroid distance of 3.688 (1) Å.

Experimental

A hot methanol solution (20 ml) of 4-aminopyridine (0.04705 g, Aldrich) and salicylic acid (0.0691 g, Merck) was warmed for 30 min over a water bath. The solution was cooled slowly and kept at room temperature. After a few days, colourless crystals were obtained.

Refinement

Atoms H1N1, H1N2, H2N2 and H1O1 were located from a difference Fourier map and were refined freely [N–H= 0.86 (2)–0.96 (2) Å and O–H = 0.97 (3) Å]. The remaining H atoms were positioned geometrically [C–H = 0.93 Å] and were refined using a riding model, with Uiso(H) = 1.2 Ueq(C).

Figures

Fig. 1.
The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Dashed line indicates the intramolecular hydrogen bond.
Fig. 2.
The crystal packing of the title compound, showing a hydrogen-bonded (dashed lines) 2D network.

Crystal data

C5H7N2+·C7H5O3F(000) = 976
Mr = 232.24Dx = 1.363 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 2403 reflections
a = 12.5801 (2) Åθ = 2.6–28.5°
b = 11.4157 (2) ŵ = 0.10 mm1
c = 15.7560 (3) ÅT = 100 K
V = 2262.73 (7) Å3Plate, colourless
Z = 80.29 × 0.17 × 0.08 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer3010 independent reflections
Radiation source: fine-focus sealed tube2303 reflections with I > 2σ(I)
graphiteRint = 0.057
[var phi] and ω scansθmax = 29.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2009)h = −17→11
Tmin = 0.971, Tmax = 0.992k = −15→15
15672 measured reflectionsl = −21→16

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)] = 0.059Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.118H atoms treated by a mixture of independent and constrained refinement
S = 1.09w = 1/[σ2(Fo2) + (0.0323P)2 + 1.7134P] where P = (Fo2 + 2Fc2)/3
3010 reflections(Δ/σ)max = 0.001
170 parametersΔρmax = 0.37 e Å3
0 restraintsΔρmin = −0.26 e Å3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
O10.93694 (11)0.70642 (11)0.39307 (9)0.0267 (3)
O21.08510 (10)0.38258 (10)0.38336 (8)0.0216 (3)
O31.08570 (10)0.56634 (10)0.43059 (8)0.0204 (3)
C10.89745 (14)0.62078 (15)0.34345 (11)0.0184 (4)
C20.80559 (14)0.64452 (17)0.29653 (12)0.0227 (4)
H2A0.77390.71800.29990.027*
C30.76181 (15)0.55938 (18)0.24519 (12)0.0255 (4)
H3A0.70030.57570.21460.031*
C40.80871 (15)0.44924 (17)0.23863 (12)0.0242 (4)
H4A0.77920.39230.20360.029*
C50.89968 (14)0.42548 (16)0.28476 (11)0.0203 (4)
H5A0.93120.35200.28020.024*
C60.94544 (13)0.50956 (15)0.33810 (11)0.0163 (3)
C71.04482 (14)0.48238 (15)0.38720 (11)0.0164 (3)
N10.76523 (12)0.02312 (13)0.49686 (9)0.0182 (3)
N21.02794 (13)0.14710 (14)0.37198 (11)0.0217 (3)
C80.82546 (14)−0.05055 (15)0.45039 (11)0.0186 (4)
H8A0.8061−0.12900.44680.022*
C90.91367 (14)−0.01310 (15)0.40865 (11)0.0178 (4)
H9A0.9543−0.06550.37720.021*
C100.94313 (13)0.10635 (14)0.41341 (11)0.0162 (3)
C110.87938 (14)0.18104 (15)0.46358 (11)0.0170 (4)
H11A0.89700.25980.46920.020*
C120.79224 (14)0.13756 (15)0.50369 (11)0.0186 (4)
H12A0.75040.18730.53640.022*
H1N10.7029 (19)−0.003 (2)0.5260 (15)0.039 (7)*
H2N21.0665 (18)0.102 (2)0.3412 (15)0.032 (6)*
H1N21.0479 (19)0.222 (2)0.3735 (15)0.042 (7)*
H1O11.000 (2)0.669 (2)0.4166 (18)0.061 (9)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0301 (8)0.0199 (7)0.0302 (8)0.0066 (6)−0.0086 (6)−0.0064 (5)
O20.0199 (6)0.0150 (6)0.0297 (7)0.0019 (5)−0.0014 (6)−0.0015 (5)
O30.0196 (6)0.0173 (6)0.0242 (7)−0.0002 (5)−0.0051 (5)−0.0032 (5)
C10.0177 (8)0.0214 (9)0.0162 (9)−0.0010 (7)0.0016 (7)−0.0002 (7)
C20.0191 (9)0.0280 (9)0.0210 (10)0.0050 (8)0.0032 (7)0.0042 (7)
C30.0151 (9)0.0420 (11)0.0195 (9)−0.0039 (8)−0.0022 (7)0.0081 (8)
C40.0243 (10)0.0305 (10)0.0179 (9)−0.0106 (8)−0.0027 (8)0.0005 (8)
C50.0224 (9)0.0200 (8)0.0184 (9)−0.0060 (7)0.0012 (7)0.0008 (7)
C60.0151 (8)0.0193 (8)0.0146 (8)−0.0035 (7)0.0016 (6)0.0002 (6)
C70.0154 (8)0.0176 (8)0.0162 (8)−0.0026 (7)0.0014 (7)0.0006 (6)
N10.0153 (7)0.0189 (7)0.0205 (8)−0.0016 (6)0.0007 (6)0.0020 (6)
N20.0219 (8)0.0166 (8)0.0265 (9)−0.0017 (7)0.0073 (7)−0.0021 (6)
C80.0201 (9)0.0148 (8)0.0209 (9)−0.0010 (7)−0.0027 (7)0.0003 (7)
C90.0195 (8)0.0149 (8)0.0190 (9)0.0021 (7)0.0005 (7)−0.0014 (6)
C100.0158 (8)0.0174 (8)0.0155 (8)0.0003 (6)−0.0020 (7)0.0014 (6)
C110.0191 (9)0.0147 (8)0.0171 (9)0.0006 (7)−0.0025 (7)−0.0009 (6)
C120.0200 (9)0.0183 (8)0.0175 (9)0.0036 (7)−0.0009 (7)−0.0016 (7)

Geometric parameters (Å, °)

O1—C11.347 (2)N1—C81.348 (2)
O1—H1O10.97 (3)N1—C121.354 (2)
O2—C71.248 (2)N1—H1N10.96 (2)
O3—C71.285 (2)N2—C101.335 (2)
C1—C21.398 (3)N2—H2N20.86 (2)
C1—C61.408 (2)N2—H1N20.89 (3)
C2—C31.379 (3)C8—C91.359 (2)
C2—H2A0.93C8—H8A0.93
C3—C41.393 (3)C9—C101.415 (2)
C3—H3A0.93C9—H9A0.93
C4—C51.382 (3)C10—C111.412 (2)
C4—H4A0.93C11—C121.359 (2)
C5—C61.400 (2)C11—H11A0.93
C5—H5A0.93C12—H12A0.93
C6—C71.503 (2)
C1—O1—H1O1101.7 (16)C8—N1—C12120.26 (16)
O1—C1—C2118.11 (16)C8—N1—H1N1122.0 (14)
O1—C1—C6122.07 (16)C12—N1—H1N1117.7 (14)
C2—C1—C6119.82 (16)C10—N2—H2N2121.1 (15)
C3—C2—C1120.23 (17)C10—N2—H1N2123.1 (16)
C3—C2—H2A119.9H2N2—N2—H1N2116 (2)
C1—C2—H2A119.9N1—C8—C9121.71 (16)
C2—C3—C4120.70 (18)N1—C8—H8A119.1
C2—C3—H3A119.7C9—C8—H8A119.1
C4—C3—H3A119.7C8—C9—C10119.43 (16)
C5—C4—C3119.26 (17)C8—C9—H9A120.3
C5—C4—H4A120.4C10—C9—H9A120.3
C3—C4—H4A120.4N2—C10—C11121.15 (16)
C4—C5—C6121.44 (17)N2—C10—C9121.29 (16)
C4—C5—H5A119.3C11—C10—C9117.56 (16)
C6—C5—H5A119.3C12—C11—C10119.85 (16)
C5—C6—C1118.54 (16)C12—C11—H11A120.1
C5—C6—C7120.65 (16)C10—C11—H11A120.1
C1—C6—C7120.80 (15)N1—C12—C11121.17 (16)
O2—C7—O3122.97 (16)N1—C12—H12A119.4
O2—C7—C6120.08 (15)C11—C12—H12A119.4
O3—C7—C6116.94 (15)
O1—C1—C2—C3−179.61 (17)C1—C6—C7—O2178.36 (16)
C6—C1—C2—C30.1 (3)C5—C6—C7—O3175.74 (16)
C1—C2—C3—C4−0.6 (3)C1—C6—C7—O3−3.0 (2)
C2—C3—C4—C50.5 (3)C12—N1—C8—C9−0.6 (3)
C3—C4—C5—C60.2 (3)N1—C8—C9—C10−0.4 (3)
C4—C5—C6—C1−0.7 (3)C8—C9—C10—N2−178.64 (17)
C4—C5—C6—C7−179.52 (16)C8—C9—C10—C111.3 (2)
O1—C1—C6—C5−179.75 (16)N2—C10—C11—C12178.68 (17)
C2—C1—C6—C50.6 (2)C9—C10—C11—C12−1.2 (2)
O1—C1—C6—C7−0.9 (3)C8—N1—C12—C110.6 (3)
C2—C1—C6—C7179.35 (16)C10—C11—C12—N10.3 (3)
C5—C6—C7—O2−2.9 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1N1···O2i0.96 (2)2.48 (2)3.1394 (19)126 (2)
N1—H1N1···O3i0.96 (2)1.78 (2)2.7296 (19)172 (2)
N2—H1N2···O20.89 (2)1.90 (2)2.789 (2)176 (2)
O1—H1O1···O30.97 (3)1.61 (2)2.5316 (18)157 (2)
C11—H11A···O3ii0.932.553.360 (2)146
C12—H12A···O2i0.932.563.164 (2)123

Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) −x+2, −y+1, −z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CI5130).

References

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