4-Amino­pyridinium 4-amino­benzene­sulfonate 4-ammonio­benzene­sulfonate monohydrate

Hoong-Kun Fun; Samuel Robinson Jebas; A Sinthiya

doi:10.1107/S1600536808006259

. 2008 Mar 12;64(Pt 4):o697–o698. doi: 10.1107/S1600536808006259

4-Aminopyridinium 4-aminobenzenesulfonate 4-ammoniobenzenesulfonate monohydrate

Hoong-Kun Fun ^a,^*, Samuel Robinson Jebas ^a,^‡, A Sinthiya ^b

PMCID: PMC2960977 PMID: 21202089

Abstract

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—π interactions into a three-dimensional framework.

Related literature

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

Crystal data

C₅H₇N₂ ⁺·C₆H₆NO₃S⁻·C₆H₇NO₃S·H₂O
M _r = 458.53
Monoclinic,
a = 24.9902 (2) Å
b = 5.7475 (1) Å
c = 15.1930 (1) Å
β = 115.415 (1)°
V = 1971.00 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.32 mm⁻¹
T = 100.0 (1) K
0.35 × 0.18 × 0.08 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.895, T _max = 0.972
30055 measured reflections
9157 independent reflections
7528 reflections with I > 2σ(I)
R _int = 0.051

Refinement

R[F ² > 2σ(F ²)] = 0.048
wR(F ²) = 0.114
S = 1.06
9157 reflections
272 parameters
6 restraints
H-atom parameters constrained
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.66 e Å⁻³
Absolute structure: Flack (1983 ▶), 4029 Friedel pairs
Flack parameter: −0.01 (4)

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

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808006259/ci2568sup1.cif

e-64-0o697-sup1.cif^{(20.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808006259/ci2568Isup2.hkl

e-64-0o697-Isup2.hkl^{(246.1KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4B⋯O1Wⁱ	0.86	2.01	2.869 (2)	179
N2—H3N2⋯O3ⁱⁱ	0.90	1.98	2.8542 (19)	164
N1—H1N1⋯O6ⁱ	0.90	2.15	3.0111 (19)	160
N2—H1N2⋯O2ⁱⁱⁱ	0.90	1.92	2.8101 (19)	168
N2—H1N2⋯S1ⁱⁱⁱ	0.90	2.84	3.6066 (15)	144
N3—H1N3⋯O1^iv	0.90	2.13	2.879 (2)	140
N3—H1N3⋯O2W^v	0.90	2.26	2.928 (2)	131
N2—H2N2⋯N1^vi	0.90	1.91	2.799 (2)	168
N4—H4A⋯O4	0.86	2.14	2.9929 (19)	175
N1—H2N1⋯O5	0.90	2.19	3.0386 (19)	158
O1W—H1W1⋯O4^vii	0.87	1.88	2.7189 (15)	162
O2W—H1W2⋯O3	0.87	1.96	2.7921 (14)	160
C12—H12A⋯Cg1^vi	0.93	2.96	3.614 (19)	129

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) . Cg1 is the centroid of the C7–C12 benzene ring.

Acknowledgments

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.

supplementary crystallographic information

Comment

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.

Experimental

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.