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Acta Cryst. (2008). E64, o697-o698    [ doi:10.1107/S1600536808006259 ]

4-Aminopyridinium 4-aminobenzenesulfonate 4-ammoniobenzenesulfonate monohydrate

H.-K. Fun, S. R. Jebas and A. Sinthiya

Abstract top

The asymmetric unit of the title compound, C5H7N2+·C6H6NO3S-·C6H7NO3S·H2O, contains one 4-ammoniobenzenesulfonate zwitterion (+H3NC6H4SO3-), one 4-aminobenzenesulfonate anion (H2NC6H4SO3-), one 4-aminopyridinium cation and two half-molecules of water, each lying on a twofold rotation axis. The various ions and molecules in the structure are linked through N-H...O, N-H...N and N-H...S hydrogen bonds and C-H-[pi] interactions into a three-dimensional framework.

Comment top

4-Aminopyridine (Fampridine) is used clinically in Lambert-Eaton myasthenic syndrome and multiple sclerosis because by blocking potassium channels it prolongs the action potentials thereby increasing the transmitter release at the neuromuscular junction (Judge et al., 2006; Schwid et al., 1997; Strupp et al., 2004). The crystal structure of 4-aminopyridine has already been reported (Chao & Schempp, 1977; Anderson et al., 2005). Sulfanilic acid (4-aminobenzenesulfonic acid or p-anilinesulfonic acid) readily forms diazo compounds and is used to make dyes and sulpha drugs. The crystal structure of monoclinic and orthorhombic polymorphs of sulfanilic acid monohydrate have been reported (Rae & Maslen, 1962; Banu & Golzar Hossain, 2006).

The asymmetric unit of the title compound contains one 4-ammoniobenzenesulfonate zwitterion (+H3NC6H4SO3-), one 4-aminobenzenesulfonate anion (H2NC6H4SO3-), one 4-aminopyridinium cation and one-half of two water molecules both lying on a twofold rotation axis.

The bond lengths and angles of the 4-aminopyridinium cation agree with those previously reported (Chao & Schempp, 1977; Anderson et al., 2005). A decrease in the C13—N4 bond length [1.326 (2) Å] is observed. Protonation of atom N3 of the 4-aminopyridine results in the widening of the C15—N3—C16 angle to 120.53 (15)° which is 115.25 (3)° in the neutral 4-aminopyridine molecule (Chao & Schempp, 1977; Anderson et al., 2005). The pyridinium ring is essentially planar, with a maximium deviation of 0.007 (1) Å for atom C13.

The bond lengths and angles of the 4-ammoniobenzenesulfonate zwitterion 4-aminobenzenesulfonate anion are found to be essentially the same and agree with those reported earlier (Rae & Maslen, 1962; Banu & Golzar Hossain, 2006). The C9—C10—C11 [122.08 (14) Å] angle in the zwitterion is widened compared to the corresponding angle [C3—C4—C5 119.18 (14) Å] in the 4-aminobenzenesulfonate anion. The aromatic rings of the anion and zwitterion are found to be planar, with maximium deviations of 0.019 (2) and 0.010 (2) Å, respectively, for atoms C4 and C7. Within the asymmetric unit, pyridinium ring forms dihedral angles of 9.52 (9)° and 6.19 (9)°, respectively, with the C1—C6 and C7—C12 rings. The dihedral angle between the C1—C6 and C7—C12 rings is 5.29 (9)°.

In the crystal structure, the cations and anions/zwitterions are stacked into layers parallel to the bc plane (Fig. 2). All sulfonyl oxygen atoms are involved in hydrogen bonding with the amino group. The water molecules link the various ions into a three-dimensional framework. A π-π stacking interaction is observed between the pyridinium ring (C13—C17/N3) and the C1—C6 benzene ring of the anion, with a centroid to centroid distance of 3.737 (1) Å. The crystal structure is further stabilized by weak C12—H12A···π interactions involving the C7—C12 benzene ring of the zwitterion.

Related literature top

For related literature, see: Anderson et al. (2005); Banu & Golzar Hossain (2006); Chao & Schempp (1977); Judge & Bever (2006); Rae & Maslen (1962); Schwid et al. (1997); Strupp et al. (2004).

Experimental top

Solutions of 4-aminopyridine and sulfanilic acid in ethanol were mixed in a molar ratio of 1:2. The solution was stirred well for 30 min and heated at 303 K for 2 h. Yellow crystals of the title compound were obtained by slow evaporation after a period of two weeks.

Refinement top

After checking their presence in a difference map, all H atoms were placed in calculated positions (C—H = 0.93 Å and N—H = 0.86 or 0.90 Å) and refined using a riding model, with Uiso(H) = 1.2Ueq(C,N).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering.
[Figure 2] Fig. 2. The crystal packing of the title compound, viewed approximately down the c axis. Hydrogen bonds are shown as dashed lines.
4-Aminopyridinium 4-aminobenzenesulfonate 4-ammoniobenzenesulfonate monohydrate top
Crystal data top
C5H7N2+·C6H6NO3S–·C6H7NO3S·H2OF000 = 960
Mr = 458.53Dx = 1.545 Mg m−3
Monoclinic, C2Mo Kα radiation
λ = 0.71073 Å
Hall symbol: C 2yCell parameters from 6986 reflections
a = 24.9902 (2) Åθ = 2.7–35.1º
b = 5.7475 (1) ŵ = 0.32 mm−1
c = 15.1930 (1) ÅT = 100.0 (1) K
β = 115.415 (1)ºPlate, yellow
V = 1971.00 (4) Å30.35 × 0.18 × 0.08 mm
Z = 4
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		Rint = 0.051
φ and ω scansθmax = 36.2º
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		θmin = 1.5º
Tmin = 0.895, Tmax = 0.972h = −41→41
30055 measured reflectionsk = −9→9
9157 independent reflectionsl = −25→25
7528 reflections with I > 2σ(I)
Refinement top
Refinement on F2H-atom parameters constrained
Least-squares matrix: full  w = 1/[σ2(Fo2) + (0.0544P)2]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.048(Δ/σ)max = 0.001
wR(F2) = 0.114Δρmax = 0.43 e Å−3
S = 1.06Δρmin = −0.66 e Å−3
9157 reflectionsExtinction correction: none
272 parametersAbsolute structure: Flack (1983), 4029 Friedel pairs
6 restraintsFlack parameter: −0.01 (4)
Crystal data top
C5H7N2+·C6H6NO3S–·C6H7NO3S·H2OV = 1971.00 (4) Å3
Mr = 458.53Z = 4
Monoclinic, C2Mo Kα
a = 24.9902 (2) ŵ = 0.32 mm−1
b = 5.7475 (1) ÅT = 100.0 (1) K
c = 15.1930 (1) Å0.35 × 0.18 × 0.08 mm
β = 115.415 (1)º
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		9157 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		7528 reflections with I > 2σ(I)
Tmin = 0.895, Tmax = 0.972Rint = 0.051
30055 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.048H-atom parameters constrained
wR(F2) = 0.114Δρmax = 0.43 e Å−3
S = 1.06Δρmin = −0.66 e Å−3
9157 reflectionsAbsolute structure: Flack (1983), 4029 Friedel pairs
272 parametersFlack parameter: −0.01 (4)
6 restraints
Special details top

Geometry. Experimental. The low-temperature data was collected with the Oxford Crysosystem Cobra low-temperature attachement.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
S10.367717 (17)0.30668 (6)−0.07087 (3)0.01197 (7)
S20.349420 (17)1.00691 (6)0.42455 (3)0.01122 (7)
O10.41498 (6)0.4675 (2)−0.06022 (10)0.0217 (3)
O20.31451 (5)0.3430 (2)−0.16138 (8)0.0158 (2)
O30.38660 (5)0.0621 (2)−0.06024 (9)0.0157 (2)
O40.39347 (5)0.8372 (2)0.42552 (8)0.0146 (2)
O50.29296 (5)0.9811 (2)0.33955 (8)0.0147 (2)
O60.37175 (5)1.2447 (2)0.43941 (8)0.0148 (2)
N10.30210 (6)0.5120 (3)0.25477 (10)0.0144 (2)
H1N10.330.4560.31110.017*
H2N10.29630.66340.2630.017*
N20.30594 (6)0.8065 (3)0.77520 (9)0.0129 (2)
H1N20.30840.65270.78750.016*
H2N20.26910.85280.76350.016*
H3N20.33640.86640.82750.016*
N30.50936 (7)0.5548 (3)0.15575 (11)0.0228 (3)
H1N30.52010.57860.10720.027*
N40.46259 (7)0.4675 (3)0.38104 (11)0.0205 (3)
H4A0.44060.56910.39110.025*
H4B0.47420.34620.41750.025*
C10.34758 (7)0.3645 (3)0.02502 (11)0.0106 (3)
C20.35850 (7)0.2020 (3)0.09866 (11)0.0142 (3)
H2A0.37590.06010.09690.017*
C30.34344 (8)0.2509 (3)0.17467 (12)0.0145 (3)
H3A0.35070.14140.22360.017*
C40.31746 (7)0.4633 (3)0.17813 (11)0.0120 (3)
C50.30432 (7)0.6223 (3)0.10179 (12)0.0142 (3)
H5A0.28520.76120.10170.017*
C60.31977 (7)0.5733 (3)0.02616 (12)0.0145 (3)
H6A0.31150.6805−0.02390.017*
C70.33669 (7)0.9400 (3)0.52796 (11)0.0110 (3)
C80.35436 (7)0.7288 (3)0.57586 (12)0.0143 (3)
H8A0.3730.61820.5540.017*
C90.34381 (8)0.6843 (3)0.65743 (12)0.0144 (3)
H9A0.35550.54380.69060.017*
C100.31584 (7)0.8516 (3)0.68843 (11)0.0112 (3)
C110.29681 (7)1.0617 (3)0.63989 (12)0.0132 (3)
H11A0.27741.17070.6610.016*
C120.30754 (7)1.1049 (3)0.55864 (11)0.0133 (3)
H12A0.29521.24430.52480.016*
C130.47866 (7)0.4979 (3)0.30921 (12)0.0164 (3)
C140.51422 (8)0.3311 (3)0.28971 (14)0.0211 (3)
H14A0.52780.19980.32880.025*
C150.52825 (8)0.3652 (4)0.21303 (14)0.0218 (4)
H15A0.55130.25540.20020.026*
C160.47601 (9)0.7162 (4)0.17268 (14)0.0244 (4)
H16A0.46320.84550.13220.029*
C170.46057 (8)0.6940 (4)0.24815 (13)0.0213 (4)
H17A0.4380.80890.25920.026*
O1W0.51.0580 (4)0.50.0317 (5)
H1W10.52960.96260.52530.048*
O2W0.5−0.1247 (3)00.0196 (4)
H1W20.4689−0.035−0.01960.029*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.01387 (17)0.01226 (16)0.01171 (16)−0.00155 (13)0.00731 (14)−0.00131 (13)
S20.01273 (17)0.01111 (15)0.01161 (16)−0.00077 (13)0.00692 (13)−0.00047 (13)
O10.0231 (7)0.0258 (7)0.0228 (6)−0.0136 (5)0.0160 (5)−0.0090 (5)
O20.0201 (6)0.0144 (6)0.0110 (5)0.0003 (4)0.0048 (4)0.0008 (4)
O30.0170 (6)0.0153 (5)0.0146 (5)0.0045 (4)0.0067 (5)−0.0004 (4)
O40.0150 (5)0.0149 (6)0.0170 (5)0.0016 (4)0.0097 (5)−0.0016 (4)
O50.0145 (5)0.0175 (6)0.0109 (5)−0.0005 (4)0.0042 (4)−0.0014 (4)
O60.0190 (6)0.0116 (5)0.0156 (5)−0.0025 (4)0.0091 (5)−0.0001 (4)
N10.0188 (6)0.0133 (6)0.0140 (6)0.0011 (5)0.0097 (5)−0.0005 (5)
N20.0156 (6)0.0125 (5)0.0113 (5)−0.0002 (5)0.0064 (5)0.0001 (5)
N30.0204 (8)0.0333 (9)0.0189 (7)−0.0037 (6)0.0123 (6)−0.0033 (6)
N40.0241 (8)0.0220 (8)0.0209 (7)0.0005 (6)0.0150 (6)−0.0014 (5)
C10.0105 (6)0.0109 (6)0.0104 (6)−0.0007 (5)0.0045 (5)−0.0002 (5)
C20.0176 (8)0.0123 (6)0.0144 (7)0.0022 (5)0.0085 (6)0.0015 (5)
C30.0195 (8)0.0118 (6)0.0148 (7)0.0020 (5)0.0097 (6)0.0029 (5)
C40.0118 (7)0.0128 (7)0.0125 (6)−0.0011 (5)0.0063 (6)−0.0010 (5)
C50.0168 (8)0.0116 (6)0.0157 (7)0.0009 (5)0.0085 (6)0.0004 (5)
C60.0182 (8)0.0127 (6)0.0135 (7)0.0015 (6)0.0074 (6)0.0014 (5)
C70.0116 (7)0.0112 (6)0.0110 (6)−0.0004 (5)0.0057 (5)−0.0003 (5)
C80.0176 (8)0.0119 (6)0.0149 (7)0.0032 (6)0.0087 (6)0.0014 (5)
C90.0178 (8)0.0120 (6)0.0157 (7)0.0024 (5)0.0092 (6)0.0018 (5)
C100.0123 (7)0.0113 (6)0.0104 (6)−0.0009 (5)0.0053 (5)0.0000 (5)
C110.0158 (7)0.0116 (6)0.0141 (7)0.0009 (5)0.0082 (6)−0.0004 (5)
C120.0168 (7)0.0115 (6)0.0124 (7)0.0008 (5)0.0071 (6)0.0010 (5)
C130.0134 (7)0.0201 (7)0.0165 (7)−0.0022 (6)0.0073 (6)−0.0046 (6)
C140.0219 (9)0.0196 (8)0.0250 (9)−0.0014 (7)0.0132 (7)−0.0031 (7)
C150.0204 (9)0.0253 (9)0.0241 (9)−0.0032 (7)0.0136 (7)−0.0067 (7)
C160.0215 (9)0.0315 (10)0.0232 (9)0.0013 (8)0.0123 (8)0.0046 (8)
C170.0192 (9)0.0255 (9)0.0221 (9)0.0040 (7)0.0116 (7)0.0017 (7)
O1W0.0145 (9)0.0162 (9)0.0556 (14)00.0067 (9)0
O2W0.0160 (8)0.0161 (8)0.0278 (10)00.0104 (7)0
Geometric parameters (Å, °) top
S1—O11.4531 (13)C3—H3A0.93
S1—O21.4604 (12)C4—C51.400 (2)
S1—O31.4692 (13)C5—C61.389 (2)
S1—C11.7651 (15)C5—H5A0.93
S2—O51.4548 (12)C6—H6A0.93
S2—O61.4570 (13)C7—C81.386 (2)
S2—O41.4661 (12)C7—C121.392 (2)
S2—C71.7737 (15)C8—C91.397 (2)
N1—C41.4016 (19)C8—H8A0.93
N1—H1N10.90C9—C101.385 (2)
N1—H2N10.90C9—H9A0.93
N2—C101.4650 (19)C10—C111.388 (2)
N2—H1N20.90C11—C121.393 (2)
N2—H2N20.90C11—H11A0.93
N2—H3N20.90C12—H12A0.93
N3—C161.343 (3)C13—C171.405 (3)
N3—C151.347 (3)C13—C141.422 (2)
N3—H1N30.90C14—C151.367 (3)
N4—C131.326 (2)C14—H14A0.93
N4—H4A0.86C15—H15A0.93
N4—H4B0.86C16—C171.364 (2)
C1—C61.391 (2)C16—H16A0.93
C1—C21.392 (2)C17—H17A0.93
C2—C31.388 (2)O1W—H1W10.87
C2—H2A0.93O2W—H1W20.87
C3—C41.395 (2)
O1—S1—O2112.46 (8)C6—C5—C4120.22 (15)
O1—S1—O3112.88 (8)C6—C5—H5A119.9
O2—S1—O3111.08 (7)C4—C5—H5A119.9
O1—S1—C1107.12 (7)C5—C6—C1120.20 (14)
O2—S1—C1106.46 (7)C5—C6—H6A119.9
O3—S1—C1106.34 (7)C1—C6—H6A119.9
O5—S2—O6113.23 (7)C8—C7—C12120.98 (14)
O5—S2—O4112.27 (7)C8—C7—S2121.12 (12)
O6—S2—O4112.74 (7)C12—C7—S2117.90 (12)
O5—S2—C7106.85 (7)C7—C8—C9119.16 (15)
O6—S2—C7105.57 (7)C7—C8—H8A120.4
O4—S2—C7105.45 (7)C9—C8—H8A120.4
C4—N1—H1N1109.9C10—C9—C8119.31 (15)
C4—N1—H2N1115.3C10—C9—H9A120.3
H1N1—N1—H2N1108.6C8—C9—H9A120.3
C10—N2—H1N2109.7C9—C10—C11122.08 (14)
C10—N2—H2N2108.9C9—C10—N2119.21 (14)
H1N2—N2—H2N2107.7C11—C10—N2118.71 (14)
C10—N2—H3N2108.7C10—C11—C12118.26 (15)
H1N2—N2—H3N2103.7C10—C11—H11A120.9
H2N2—N2—H3N2117.9C12—C11—H11A120.9
C16—N3—C15120.58 (15)C7—C12—C11120.19 (15)
C16—N3—H1N3118.7C7—C12—H12A119.9
C15—N3—H1N3120.6C11—C12—H12A119.9
C13—N4—H4A120N4—C13—C17121.57 (16)
C13—N4—H4B120N4—C13—C14121.31 (17)
H4A—N4—H4B120C17—C13—C14117.11 (16)
C6—C1—C2119.74 (14)C15—C14—C13119.51 (18)
C6—C1—S1119.59 (12)C15—C14—H14A120.2
C2—C1—S1120.67 (12)C13—C14—H14A120.2
C3—C2—C1120.20 (15)N3—C15—C14121.31 (17)
C3—C2—H2A119.9N3—C15—H15A119.3
C1—C2—H2A119.9C14—C15—H15A119.3
C2—C3—C4120.37 (15)N3—C16—C17121.27 (19)
C2—C3—H3A119.8N3—C16—H16A119.4
C4—C3—H3A119.8C17—C16—H16A119.4
C3—C4—C5119.18 (14)C16—C17—C13120.20 (18)
C3—C4—N1120.25 (14)C16—C17—H17A119.9
C5—C4—N1120.50 (14)C13—C17—H17A119.9
O1—S1—C1—C668.17 (14)O6—S2—C7—C1245.63 (14)
O2—S1—C1—C6−52.35 (14)O4—S2—C7—C12165.19 (12)
O3—S1—C1—C6−170.88 (13)C12—C7—C8—C9−1.5 (2)
O1—S1—C1—C2−112.74 (14)S2—C7—C8—C9179.53 (13)
O2—S1—C1—C2126.73 (13)C7—C8—C9—C100.2 (2)
O3—S1—C1—C28.21 (15)C8—C9—C10—C111.2 (2)
C6—C1—C2—C3−2.1 (2)C8—C9—C10—N2−178.73 (15)
S1—C1—C2—C3178.85 (13)C9—C10—C11—C12−1.3 (2)
C1—C2—C3—C4−0.2 (2)N2—C10—C11—C12178.68 (14)
C2—C3—C4—C52.8 (2)C8—C7—C12—C111.4 (2)
C2—C3—C4—N1179.77 (15)S2—C7—C12—C11−179.55 (12)
C3—C4—C5—C6−3.2 (2)C10—C11—C12—C7−0.1 (2)
N1—C4—C5—C6179.86 (15)N4—C13—C14—C15177.91 (17)
C4—C5—C6—C11.0 (2)C17—C13—C14—C15−1.1 (3)
C2—C1—C6—C51.7 (2)C16—N3—C15—C140.0 (3)
S1—C1—C6—C5−179.22 (13)C13—C14—C15—N30.4 (3)
O5—S2—C7—C8103.83 (14)C15—N3—C16—C170.3 (3)
O6—S2—C7—C8−135.36 (14)N3—C16—C17—C13−1.1 (3)
O4—S2—C7—C8−15.81 (15)N4—C13—C17—C16−177.60 (18)
O5—S2—C7—C12−75.17 (14)C14—C13—C17—C161.4 (3)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N4—H4B···O1Wi0.862.012.869 (2)179
N2—H3N2···O3ii0.901.982.8542 (19)164
N1—H1N1···O6i0.902.153.0111 (19)160
N2—H1N2···O2iii0.901.922.8101 (19)168
N2—H1N2···S1iii0.902.843.6066 (15)144
N3—H1N3···O1iv0.902.132.879 (2)140
N3—H1N3···O2Wv0.902.262.928 (2)131
N2—H2N2···N1vi0.901.912.799 (2)168
N4—H4A···O40.862.142.9929 (19)175
N1—H2N1···O50.902.193.0386 (19)158
O1W—H1W1···O4vii0.871.882.7189 (15)162
O2W—H1W2···O30.871.962.7921 (14)160
C12—H12A···Cg1vi0.932.963.614 (19)129
Symmetry codes: (i) x, y−1, z; (ii) x, y+1, z+1; (iii) x, y, z+1; (iv) −x+1, y, −z; (v) x, y+1, z; (vi) −x+1/2, y+1/2, −z+1; (vii) −x+1, y, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N4—H4B···O1Wi0.862.012.869 (2)179
N2—H3N2···O3ii0.901.982.8542 (19)164
N1—H1N1···O6i0.902.153.0111 (19)160
N2—H1N2···O2iii0.901.922.8101 (19)168
N2—H1N2···S1iii0.902.843.6066 (15)144
N3—H1N3···O1iv0.902.132.879 (2)140
N3—H1N3···O2Wv0.902.262.928 (2)131
N2—H2N2···N1vi0.901.912.799 (2)168
N4—H4A···O40.862.142.9929 (19)175
N1—H2N1···O50.902.193.0386 (19)158
O1W—H1W1···O4vii0.871.882.7189 (15)162
O2W—H1W2···O30.871.962.7921 (14)160
C12—H12A···Cg1vi0.932.963.614 (19)129
Symmetry codes: (i) x, y−1, z; (ii) x, y+1, z+1; (iii) x, y, z+1; (iv) −x+1, y, −z; (v) x, y+1, z; (vi) −x+1/2, y+1/2, −z+1; (vii) −x+1, y, −z+1.
Acknowledgements top

FHK and SRJ thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. SRJ thanks the Universiti Sains Malaysia for the award of a post-doctoral research fellowship.

references
References top

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