organic compounds
2,3-Diaminopyridinium 4-hydroxybenzoate
aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 Universiti Sains Malaysia, Penang, Malaysia
*Correspondence e-mail: hkfun@usm.my
In the title compound, C5H8N3+·C7H5O3−, the pyridine N atom is protonated. In the 4-hydroxybenzoate anion, the carboxylate group is twisted slightly out of the benzene ring plane by an angle of 3.77 (5)°. The protonated N atom and one of the two amino groups are hydrogen-bonded to the 4-hydroxybenzoate anion through a pair of N—H⋯O hydrogen bonds, forming an R22(8) ring motif. The is further stabilized by O—H⋯O and C—H⋯O hydrogen bonds and π–π interactions involving the pyridinium rings [centroid–centroid distance of 3.6277 (5) Å], leading to the formation of a three-dimensional network.
Related literature
For general background to substituted pyridines, see: Pozharski et al. (1997); Katritzky et al. (1996). For details of hydrogen bonding, see: Jeffrey & Saenger (1991); Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).
Experimental
Crystal data
|
Refinement
|
Data collection: APEX2 (Bruker, 2005); cell SAINT (Bruker, 2005); data reduction: SAINT; 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, 2009).
Supporting information
10.1107/S1600536809020832/ci2813sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809020832/ci2813Isup2.hkl
Hot methanol solutions (20 ml) of 2,3-diaminopyridine (27 mg, Aldrich) and 4-hydroxybenzoic acid (35 mg, Merck) were mixed and warmed over a heating magnetic stirrer for 5 minutes. The resulting solution was allowed to cool slowly at room temperature. Crystals of the title compound appeared from the mother liquor after a few days.
All the H atoms were located in a difference Fourier map and allowed to refine freely [N–H = 0.86–0.91 Å, C–H = 0.95–1.01 (15)Å and O–H = 0.89 (18) Å]
Data collection: APEX2 (Bruker, 2005); cell
SAINT (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, 2009).Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme. Dashed lines indicate hydrogen bonds. | |
Fig. 2. Crystal packing of the title compound, showing a part of the three-dimensional network. Hydrogen bonds are shown as dashed lines. |
C5H8N3+·C7H5O3− | F(000) = 520 |
Mr = 247.25 | Dx = 1.356 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 9979 reflections |
a = 10.2915 (2) Å | θ = 2.7–37.8° |
b = 11.4946 (2) Å | µ = 0.10 mm−1 |
c = 11.0921 (2) Å | T = 100 K |
β = 112.644 (1)° | Plate, brown |
V = 1211.01 (4) Å3 | 0.51 × 0.39 × 0.14 mm |
Z = 4 |
Bruker SMART APEXII CCD area-detector diffractometer | 5296 independent reflections |
Radiation source: fine-focus sealed tube | 4257 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.034 |
ϕ and ω scans | θmax = 35.0°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −16→16 |
Tmin = 0.950, Tmax = 0.986 | k = −16→18 |
25821 measured reflections | l = −17→17 |
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.138 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0817P)2 + 0.1673P] where P = (Fo2 + 2Fc2)/3 |
5296 reflections | (Δ/σ)max = 0.001 |
215 parameters | Δρmax = 0.65 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
C5H8N3+·C7H5O3− | V = 1211.01 (4) Å3 |
Mr = 247.25 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.2915 (2) Å | µ = 0.10 mm−1 |
b = 11.4946 (2) Å | T = 100 K |
c = 11.0921 (2) Å | 0.51 × 0.39 × 0.14 mm |
β = 112.644 (1)° |
Bruker SMART APEXII CCD area-detector diffractometer | 5296 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 4257 reflections with I > 2σ(I) |
Tmin = 0.950, Tmax = 0.986 | Rint = 0.034 |
25821 measured reflections |
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.138 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.65 e Å−3 |
5296 reflections | Δρmin = −0.19 e Å−3 |
215 parameters |
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems 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 > 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 | ||
O1 | 0.45467 (8) | 0.16900 (6) | 0.43336 (6) | 0.02563 (15) | |
O2 | 0.84786 (7) | 0.61461 (5) | 0.52034 (5) | 0.02074 (13) | |
O3 | 0.73136 (6) | 0.62156 (5) | 0.30541 (5) | 0.01784 (12) | |
N1 | 1.01845 (8) | 0.79427 (6) | 0.49674 (6) | 0.01857 (14) | |
N2 | 0.87767 (8) | 0.81703 (7) | 0.27844 (7) | 0.02195 (15) | |
N3 | 1.05767 (9) | 0.99458 (8) | 0.25977 (7) | 0.02666 (17) | |
C1 | 0.57827 (9) | 0.42070 (7) | 0.30431 (7) | 0.01757 (14) | |
C2 | 0.50323 (9) | 0.32084 (7) | 0.30618 (7) | 0.01879 (15) | |
C3 | 0.52248 (9) | 0.26810 (7) | 0.42538 (7) | 0.01899 (15) | |
C4 | 0.61617 (11) | 0.31656 (8) | 0.54174 (8) | 0.02518 (18) | |
C5 | 0.69083 (10) | 0.41624 (8) | 0.53881 (7) | 0.02324 (17) | |
C6 | 0.67313 (8) | 0.46970 (7) | 0.41995 (7) | 0.01604 (14) | |
C7 | 0.75521 (8) | 0.57533 (6) | 0.41592 (7) | 0.01540 (14) | |
C8 | 0.99181 (9) | 0.84838 (7) | 0.38181 (7) | 0.01678 (14) | |
C9 | 1.08674 (9) | 0.93716 (7) | 0.37590 (7) | 0.01803 (15) | |
C10 | 1.20049 (9) | 0.96332 (8) | 0.48910 (8) | 0.02092 (16) | |
C11 | 1.22331 (9) | 0.90438 (8) | 0.60700 (8) | 0.02314 (17) | |
C12 | 1.13117 (10) | 0.82008 (8) | 0.60867 (8) | 0.02224 (17) | |
H1 | 0.5647 (15) | 0.4565 (11) | 0.2226 (13) | 0.031 (3)* | |
H2 | 0.4376 (14) | 0.2854 (12) | 0.2229 (13) | 0.029 (3)* | |
H4 | 0.6280 (18) | 0.2759 (15) | 0.6232 (17) | 0.051 (4)* | |
H5 | 0.7615 (17) | 0.4479 (13) | 0.6225 (15) | 0.039 (4)* | |
H10 | 1.2669 (14) | 1.0227 (12) | 0.4848 (12) | 0.028 (3)* | |
H11 | 1.3091 (16) | 0.9246 (13) | 0.6883 (14) | 0.039 (4)* | |
H12 | 1.1341 (17) | 0.7745 (14) | 0.6809 (15) | 0.043 (4)* | |
H1N1 | 0.9588 (15) | 0.7391 (12) | 0.4987 (13) | 0.031 (3)* | |
H1N2 | 0.8601 (17) | 0.8454 (12) | 0.2011 (15) | 0.033 (3)* | |
H2N2 | 0.8275 (15) | 0.7565 (12) | 0.2854 (13) | 0.027 (3)* | |
H1N3 | 0.9924 (17) | 0.9660 (13) | 0.1840 (15) | 0.040 (4)* | |
H2N3 | 1.1284 (16) | 1.0365 (12) | 0.2548 (14) | 0.034 (3)* | |
H1O1 | 0.3995 (19) | 0.1445 (15) | 0.3531 (18) | 0.051 (5)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0299 (3) | 0.0248 (3) | 0.0172 (3) | −0.0123 (2) | 0.0034 (2) | 0.0013 (2) |
O2 | 0.0238 (3) | 0.0217 (3) | 0.0141 (2) | −0.0059 (2) | 0.0044 (2) | −0.00153 (19) |
O3 | 0.0188 (3) | 0.0178 (3) | 0.0149 (2) | 0.0002 (2) | 0.00434 (19) | 0.00308 (19) |
N1 | 0.0200 (3) | 0.0194 (3) | 0.0148 (3) | −0.0020 (2) | 0.0051 (2) | 0.0018 (2) |
N2 | 0.0232 (3) | 0.0234 (3) | 0.0154 (3) | −0.0072 (3) | 0.0031 (2) | 0.0021 (2) |
N3 | 0.0284 (4) | 0.0324 (4) | 0.0171 (3) | −0.0118 (3) | 0.0065 (3) | 0.0037 (3) |
C1 | 0.0190 (3) | 0.0187 (3) | 0.0131 (3) | −0.0014 (3) | 0.0041 (2) | 0.0005 (2) |
C2 | 0.0198 (4) | 0.0205 (3) | 0.0131 (3) | −0.0037 (3) | 0.0031 (2) | −0.0007 (2) |
C3 | 0.0202 (4) | 0.0199 (3) | 0.0150 (3) | −0.0046 (3) | 0.0047 (3) | −0.0001 (2) |
C4 | 0.0316 (5) | 0.0273 (4) | 0.0130 (3) | −0.0114 (3) | 0.0046 (3) | 0.0008 (3) |
C5 | 0.0286 (4) | 0.0251 (4) | 0.0131 (3) | −0.0099 (3) | 0.0049 (3) | −0.0015 (3) |
C6 | 0.0173 (3) | 0.0167 (3) | 0.0131 (3) | −0.0016 (2) | 0.0048 (2) | −0.0007 (2) |
C7 | 0.0167 (3) | 0.0152 (3) | 0.0140 (3) | 0.0013 (2) | 0.0055 (2) | −0.0002 (2) |
C8 | 0.0177 (3) | 0.0174 (3) | 0.0143 (3) | −0.0003 (3) | 0.0052 (2) | 0.0001 (2) |
C9 | 0.0183 (3) | 0.0204 (3) | 0.0155 (3) | −0.0023 (3) | 0.0066 (2) | 0.0000 (2) |
C10 | 0.0192 (4) | 0.0249 (4) | 0.0178 (3) | −0.0044 (3) | 0.0062 (3) | −0.0010 (3) |
C11 | 0.0200 (4) | 0.0294 (4) | 0.0166 (3) | −0.0029 (3) | 0.0032 (3) | −0.0007 (3) |
C12 | 0.0230 (4) | 0.0262 (4) | 0.0145 (3) | −0.0014 (3) | 0.0038 (3) | 0.0023 (3) |
O1—C3 | 1.3565 (10) | C2—C3 | 1.3976 (11) |
O1—H1O1 | 0.897 (18) | C2—H2 | 0.997 (13) |
O2—C7 | 1.2666 (9) | C3—C4 | 1.3956 (11) |
O3—C7 | 1.2702 (9) | C4—C5 | 1.3869 (12) |
N1—C8 | 1.3484 (10) | C4—H4 | 0.982 (17) |
N1—C12 | 1.3661 (11) | C5—C6 | 1.4014 (11) |
N1—H1N1 | 0.888 (15) | C5—H5 | 1.001 (15) |
N2—C8 | 1.3369 (10) | C6—C7 | 1.4896 (11) |
N2—H1N2 | 0.869 (15) | C8—C9 | 1.4316 (11) |
N2—H2N2 | 0.887 (14) | C9—C10 | 1.3805 (11) |
N3—C9 | 1.3739 (10) | C10—C11 | 1.4100 (12) |
N3—H1N3 | 0.911 (16) | C10—H10 | 0.981 (14) |
N3—H2N3 | 0.892 (15) | C11—C12 | 1.3608 (13) |
C1—C2 | 1.3881 (11) | C11—H11 | 1.017 (15) |
C1—C6 | 1.3969 (10) | C12—H12 | 0.948 (15) |
C1—H1 | 0.955 (13) | ||
C3—O1—H1O1 | 110.1 (11) | C4—C5—H5 | 119.3 (8) |
C8—N1—C12 | 123.47 (7) | C6—C5—H5 | 119.9 (9) |
C8—N1—H1N1 | 117.5 (9) | C1—C6—C5 | 118.61 (7) |
C12—N1—H1N1 | 119.1 (9) | C1—C6—C7 | 120.33 (6) |
C8—N2—H1N2 | 121.7 (10) | C5—C6—C7 | 121.05 (7) |
C8—N2—H2N2 | 119.1 (9) | O2—C7—O3 | 122.08 (7) |
H1N2—N2—H2N2 | 118.2 (13) | O2—C7—C6 | 119.94 (6) |
C9—N3—H1N3 | 120.6 (10) | O3—C7—C6 | 117.96 (6) |
C9—N3—H2N3 | 115.4 (9) | N2—C8—N1 | 118.57 (7) |
H1N3—N3—H2N3 | 117.8 (13) | N2—C8—C9 | 122.86 (7) |
C2—C1—C6 | 121.05 (7) | N1—C8—C9 | 118.57 (7) |
C2—C1—H1 | 119.4 (8) | N3—C9—C10 | 123.40 (8) |
C6—C1—H1 | 119.5 (8) | N3—C9—C8 | 118.64 (7) |
C1—C2—C3 | 119.72 (7) | C10—C9—C8 | 117.92 (7) |
C1—C2—H2 | 120.4 (8) | C9—C10—C11 | 121.27 (8) |
C3—C2—H2 | 119.9 (8) | C9—C10—H10 | 118.1 (8) |
O1—C3—C4 | 117.67 (7) | C11—C10—H10 | 120.6 (8) |
O1—C3—C2 | 122.47 (7) | C12—C11—C10 | 119.12 (8) |
C4—C3—C2 | 119.85 (7) | C12—C11—H11 | 121.5 (8) |
C5—C4—C3 | 119.99 (7) | C10—C11—H11 | 119.4 (8) |
C5—C4—H4 | 122.8 (10) | C11—C12—N1 | 119.65 (7) |
C3—C4—H4 | 117.2 (10) | C11—C12—H12 | 127.5 (10) |
C4—C5—C6 | 120.78 (7) | N1—C12—H12 | 112.8 (10) |
C6—C1—C2—C3 | −0.01 (13) | C5—C6—C7—O3 | −178.02 (8) |
C1—C2—C3—O1 | −178.47 (8) | C12—N1—C8—N2 | −179.40 (8) |
C1—C2—C3—C4 | 0.46 (14) | C12—N1—C8—C9 | 0.41 (12) |
O1—C3—C4—C5 | 178.40 (9) | N2—C8—C9—N3 | 1.55 (13) |
C2—C3—C4—C5 | −0.57 (15) | N1—C8—C9—N3 | −178.25 (8) |
C3—C4—C5—C6 | 0.24 (15) | N2—C8—C9—C10 | 179.31 (8) |
C2—C1—C6—C5 | −0.32 (13) | N1—C8—C9—C10 | −0.49 (12) |
C2—C1—C6—C7 | 178.59 (7) | N3—C9—C10—C11 | 177.91 (9) |
C4—C5—C6—C1 | 0.21 (14) | C8—C9—C10—C11 | 0.26 (13) |
C4—C5—C6—C7 | −178.70 (9) | C9—C10—C11—C12 | 0.06 (14) |
C1—C6—C7—O2 | −175.21 (8) | C10—C11—C12—N1 | −0.16 (14) |
C5—C6—C7—O2 | 3.67 (12) | C8—N1—C12—C11 | −0.08 (13) |
C1—C6—C7—O3 | 3.09 (11) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N1···O2 | 0.89 (2) | 1.903 (15) | 2.7874 (9) | 173 (1) |
N2—H2N2···O3 | 0.89 (1) | 1.898 (14) | 2.7843 (9) | 176 (1) |
N2—H1N2···O2i | 0.87 (1) | 2.014 (15) | 2.8689 (9) | 168 (1) |
N3—H1N3···O2i | 0.91 (2) | 2.071 (16) | 2.9790 (10) | 174 (1) |
N3—H2N3···O3ii | 0.89 (2) | 2.057 (15) | 2.9285 (10) | 166 (1) |
O1—H1O1···O3iii | 0.90 (2) | 1.775 (19) | 2.6595 (8) | 168 (2) |
C2—H2···O3iii | 1.00 (1) | 2.500 (14) | 3.2104 (10) | 128 (1) |
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x+2, y+1/2, −z+1/2; (iii) −x+1, y−1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C5H8N3+·C7H5O3− |
Mr | 247.25 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 100 |
a, b, c (Å) | 10.2915 (2), 11.4946 (2), 11.0921 (2) |
β (°) | 112.644 (1) |
V (Å3) | 1211.01 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.51 × 0.39 × 0.14 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.950, 0.986 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 25821, 5296, 4257 |
Rint | 0.034 |
(sin θ/λ)max (Å−1) | 0.807 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.138, 1.04 |
No. of reflections | 5296 |
No. of parameters | 215 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.65, −0.19 |
Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N1···O2 | 0.89 (2) | 1.903 (15) | 2.7874 (9) | 173 (1) |
N2—H2N2···O3 | 0.89 (1) | 1.898 (14) | 2.7843 (9) | 176 (1) |
N2—H1N2···O2i | 0.87 (1) | 2.014 (15) | 2.8689 (9) | 168 (1) |
N3—H1N3···O2i | 0.91 (2) | 2.071 (16) | 2.9790 (10) | 174 (1) |
N3—H2N3···O3ii | 0.89 (2) | 2.057 (15) | 2.9285 (10) | 166 (1) |
O1—H1O1···O3iii | 0.90 (2) | 1.775 (19) | 2.6595 (8) | 168 (2) |
C2—H2···O3iii | 1.00 (1) | 2.500 (14) | 3.2104 (10) | 128 (1) |
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x+2, y+1/2, −z+1/2; (iii) −x+1, y−1/2, −z+1/2. |
Footnotes
‡Thomson Reuters ResearcherID: A-3561-2009.
Acknowledgements
HKF and KB thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. KB thanks Universiti Sains Malaysia for a post–doctoral research fellowship. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012.
References
Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–S19. CrossRef Web of Science Google Scholar
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105–107. CrossRef CAS Web of Science IUCr Journals Google Scholar
Jeffrey, G. A. (1997). An Introduction to Hydrogen Bonding. Oxford University Press. Google Scholar
Jeffrey, G. A. & Saenger, W. (1991). Hydrogen Bonding in Biological Structures. Berlin: Springer. Google Scholar
Katritzky, A. R., Rees, C. W. & Scriven, E. F. V. (1996). Comprehensive Heterocyclic Chemistry II. Oxford: Pergamon Press. Google Scholar
Pozharski, A. F., Soldatenkov, A. T. & Katritzky, A. R. (1997). Heterocycles in Life and Society. New York: Wiley. Google Scholar
Scheiner, S. (1997). Hydrogen Bonding, A Theoretical Perspective. Oxford University Press. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Pyridine and its derivatives play an important role in heterocyclic chemistry (Pozharski et al., 1997; Katritzky et al., 1996)). Pyridine and its substituted derivatives are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997;Scheiner, 1997). Since our aim is to study some interesting hydrogen-bonding interactions, the crystal structure of the title compound is presented here.
The asymmetric unit of the title compound (Fig 1), contains one 2,3-diaminopyridinium cation and one 4-hydroxybenzoate anion. The bond lengths (Allen et al., 1987) and angles are normal. The 2,3-diaminopyridinium cation is planar to within ±0.015 (1) Å. The protonation of N1 atom resulted in a slight increase in the C8—N1—C12 angle [123.47 (7)°]. In the anion, the carboxylate group is twisted slightly away from the attached ring; the dihedral angle between C1-C6 and O2/O3/C7/C6 planes is 3.77 (5)°.
In the crystal packing (Fig. 2), the protonated N1 atom and the 2-amino group (N2) is hydrogen-bonded to the carboxylate oxygen atoms (O2 and O3) via a pair of N—H···O hydrogen bonds forming a ring motif R22(8) (Bernstein et al., 1995). The amino groups (N2 and N3) are involved in N—H···O hydrogen bonding interactions to form a R12(7) ring motif. The hydroxyl group hydrogen atom is also hydrogen-bonded to the carboxylate oxygen atom through O—H···O hydrogen bonds. Moreover O—H···O and C—H···O hydrogen bonds form a R12(6) ring motif (Table 1 and Fig 2). The crystal structure is further stabilized by π-π stacking interactions between the pyridinium rings (C8—C12/N1) at (x, y, z) and (2-x, 2-y, 1-z), with a centroid-to-centroid distance of 3.6277 (5) Å.