PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2009 December 1; 65(Pt 12): o3044–o3045.
Published online 2009 November 11. doi:  10.1107/S160053680904625X
PMCID: PMC2971980

Imidazolium 4-amino­benzoate

Abstract

In the title salt, C3H5N2 +·C7H6NO2 , the carboxyl­ate group of the 4-amino­benzoate anion forms a dihedral angle of 13.23 (17)° with respect to the benzene ring. There are N—H(...)O hydrogen-bonding inter­actions between the anion and cation, and weak inter­molecular C—H(...)O contacts with carboxyl­ate O-atom acceptors of the 4-amino­benzoate anion result in extended three-dimensional R 4 4(22) and R 5 6(30) edge-fused rings along the [100], [010] and [001] directions.

Related literature

For the anti­microbial and anti­protozoal biological activity of imidazole, see: Kopanska et al. (2004 [triangle]); Sondhi et al. (2002 [triangle]). For the biological activity of 4-amino­benzoic acid, see: Lai & Marsh (1967 [triangle]); Robinson (1966 [triangle]). For related structures, see: Moreno-Fuquen et al. (1996 [triangle], 2009 [triangle]); McMullan et al. (1979 [triangle]). For hydrogen-bond motifs, see: Etter (1990 [triangle]). For hydrogen bonds, see: Nardelli (1995 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o3044-scheme1.jpg

Experimental

Crystal data

  • C3H5N2 +·C7H6NO2
  • M r = 205.22
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o3044-efi15.jpg
  • a = 7.2038 (5) Å
  • b = 11.6812 (6) Å
  • c = 12.0152 (6) Å
  • β = 105.223 (6)°
  • V = 975.59 (10) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 123 K
  • 0.20 × 0.15 × 0.12 mm

Data collection

  • Oxford Diffraction Gemini S diffractometer
  • Absorption correction: multi-scan (CrysAlis CCD; Oxford Diffraction, 2009 [triangle]) T min = 0.945, T max = 1.000
  • 8533 measured reflections
  • 2360 independent reflections
  • 1700 reflections with I > 2σ(I)
  • R int = 0.049

Refinement

  • R[F 2 > 2σ(F 2)] = 0.048
  • wR(F 2) = 0.115
  • S = 1.02
  • 2360 reflections
  • 153 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.28 e Å−3
  • Δρmin = −0.36 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2009 [triangle]); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2009 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]) and Mercury (Macrae et al., 2006 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680904625X/fj2253sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680904625X/fj2253Isup2.hkl

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

Acknowledgments

RMF is grateful to the Spanish Research Council (CSIC) for the use of a free-of-charge licence to the Cambridge Structural Database (Allen, 2002 [triangle]). RMF also wishes to thank the Universidad del Valle, Colombia, and Instituto de Química de São Carlos, Brazil for partial financial support.

supplementary crystallographic information

Comment

The title adduct, C7H6NO2-, C3H5N2+ (imidazolium 4-aminobenzoate), (I), is part of a series of studies on imidazole, which have been made in our research group (Moreno-Fuquen et al., 2009). Imidazole derivatives have a wide variety of agents holding biological activities and is used in the field of pharmaceuticals and medicine like antimicrobial and antiprotozoal (Kopanska et al., 2004) or anti-inflammatory agents (Sondhi et al., 2002). In turn, 4-Aminobenzoic acid (PABA) (Lai & Marsh, 1967) is an important biological molecule, involving the synthesis of folic acid (Robinson, 1966) and promoting the extension of hydrogen-bonded network structures. To continue research on the structural behavior of the imidazole molecule with different hydrogen bond donors, the system imidazolium 4-aminobenzoate adduct (I), is reported. The 4-aminobenzoic acid and 4-nitropyridine N-oxide (PABA+NPNO) molecular complex (Moreno-Fuquen et al., 1996) and the PABA and imidazole (IM) free molecules (McMullan et al., 1979) may be used as reference systems in order to compare to the title imidazolium salt. The molecular structure of (I) is shown in Fig. 1. The title compound shows a dihedral angle of 23.71 (8)°, between benzene and imidazole planes. In turn, the carboxylate group of 4-aminobenzoate shows a dihedral angle of 13.23 (17)° with respect to the benzene ring, following the same structural behavior of the group in the free PABA molecule and in the PABA+NPNO adduct. The (PABA), as well as other organic acids, shows the formation of centrosymmetric hydrogen-bonded dimers in its structure. As a product of the reaction with imidazole (IM), the dimer in the PABA molecule is broken, and begins the transference of the proton to the basic N-atom of the IM molecule forming the title adduct. Some structural changes in the formation of the imidazolium salt, are observed: N2—C8 bond length changes from 1.358 in the free IM molecule, to 1.3281 (17) Å in (I); C1—O1 and C6—C7 bond lengths change from 1.210 (4) and 1.366 (5) Å in the (PABA +NPNO) adduct to 1.2368 (16) and 1.3850 (18) Å in the title adduct. The other bond lengths and bond angles of (I) are in good agreement with the standard values and correspond to those observed in the IM free molecule and (PABA+NPNO) reference systems. The formation of the salt, resulting in N—H···O hydrogen-bonding interactions and C—H···O intermolecular weak contacts with carboxylate O-atoms acceptors: The two components of the adduct are connected via intermolecular N—H···O hydrogen bonds and C—H···O weak contacts, (Table 1) (Nardelli, 1995) and these interactions define an infinite three dimensional framework. In a first substructure, the strongest hydrogen bonds N—H···O interactions are responsible for crystal growth. Indeed, there are two intermolecular N—H···O hydrogen bond interactions which link one molecule of PABA and 2 molecules of IM. A third N—H···O hydrogen bond links two PABA molecules. All these interactions link the moieties into molecular sheets that extend in the b and c directions forming R56(30) (Etter, 1990) edge-fused rings (Fig. 2). In a second substructure, the PABA molecules are linked by N—H···O hydrogen-bonding and intermolecular C—H···O weak interactions which form a R44(22) e dge-fused rings along a and c directions (Fig 3). All of these interactions define the bulk structure of the crystal.

Experimental

The synthesis of the title compound (I) was carried out by slow evaporation of equimolar quantities of 4-aminobenzoic acid (0.625 g, 0.0046 mol) and imidazole (0.310 g) in 100 ml of a mixture of dry acetonitrile. Colourless blocks of a good quality, suitable for X-ray analysis with a melting point of 371 (1) K were obtained. The initial reagents were purchased from Aldrich Chemical Co., and were used as received.

Refinement

All H-atoms were located from difference maps and were positioned geometrically and refined using a riding model with C–H= 0.93–0.97 Å and Uiso(H)= 1.2Ueq(C).

Figures

Fig. 1.
An ORTEP-3 (Farrugia, 1997) plot of the title (I) compound, with the atomic labelling scheme. The shapes of the ellipsoids correspond to 50% probability contours of atomic displacement and, for the sake of clarity, H atoms are shown as spheres of arbitrary ...
Fig. 2.
The packing in the unit cell of (I) viewed down the a axis, showing the formation of R56(30) e dge-fused rings and also the hydrogen-bonding interactions as broken lines. Symmetry code: (i) -x + 1/2, y - 1/2, -z + 1/2; (ii) x - 1/2, -y + 3/2, z - 1/2; ...
Fig. 3.
The packing in the unit cell of (I) viewed down the b axis, showing the formation of R44(22) e dge-fused rings and also the hydrogen-bonding interactions as broken lines. Symmetry code: (i) x + 1/2, -y + 3/2, z - 1/2; (ii) x - 1/2, -y + 3/2, z - 1/2.

Crystal data

C3H5N2+·C7H6NO2F(000) = 432
Mr = 205.22Dx = 1.397 Mg m3
Monoclinic, P21/nMelting point: 443.0(10) K
Hall symbol: -P 2ynMo Kα radiation, λ = 0.71073 Å
a = 7.2038 (5) ÅCell parameters from 3056 reflections
b = 11.6812 (6) Åθ = 2.5–30.9°
c = 12.0152 (6) ŵ = 0.10 mm1
β = 105.223 (6)°T = 123 K
V = 975.59 (10) Å3Fragment, colourless
Z = 40.20 × 0.15 × 0.12 mm

Data collection

Oxford Diffraction Gemini S diffractometer2360 independent reflections
Radiation source: fine-focus sealed tube1700 reflections with I > 2σ(I)
graphiteRint = 0.049
ω scansθmax = 28.0°, θmin = 2.5°
Absorption correction: multi-scan (CrysAlis CCD; Oxford Diffraction, 2009)h = −9→9
Tmin = 0.945, Tmax = 1.000k = −13→15
8533 measured reflectionsl = −15→15

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.048H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.115w = 1/[σ2(Fo2) + (0.067P)2] where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
2360 reflectionsΔρmax = 0.28 e Å3
153 parametersΔρmin = −0.36 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.213 (14)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
O10.13700 (14)0.80374 (8)0.58020 (7)0.0227 (3)
O20.27846 (15)0.96304 (8)0.54056 (8)0.0243 (3)
N10.2159 (2)0.68622 (11)0.07332 (10)0.0247 (3)
N20.77001 (18)0.91059 (11)0.13156 (10)0.0246 (3)
N30.84977 (17)1.06234 (10)0.23605 (10)0.0231 (3)
C10.2104 (2)0.86668 (12)0.51343 (11)0.0201 (3)
C20.21134 (19)0.81695 (11)0.39852 (10)0.0187 (3)
C30.3206 (2)0.86798 (12)0.33249 (11)0.0218 (3)
H30.39540.93380.36130.026*
C40.3225 (2)0.82474 (12)0.22568 (11)0.0222 (3)
H40.39750.86150.18190.027*
C50.2148 (2)0.72728 (12)0.18135 (11)0.0206 (3)
C60.1034 (2)0.67656 (11)0.24708 (11)0.0212 (3)
H60.02740.61120.21810.025*
C70.10240 (19)0.72053 (11)0.35398 (11)0.0204 (3)
H70.02650.68450.39770.025*
C80.7922 (2)0.95506 (12)0.23596 (12)0.0238 (3)
H80.77010.91580.30050.029*
C90.8142 (2)0.99372 (12)0.06171 (12)0.0268 (4)
H90.80990.9859−0.01760.032*
C100.8650 (2)1.08847 (13)0.12684 (12)0.0266 (4)
H100.90391.15970.10210.032*
H1N0.175 (3)0.6098 (17)0.0598 (16)0.048 (5)*
H2N0.323 (3)0.7036 (15)0.0534 (16)0.044 (5)*
H3N0.729 (3)0.8341 (16)0.1097 (16)0.045 (5)*
H4N0.860 (3)1.1143 (18)0.2961 (19)0.060 (6)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0297 (6)0.0203 (5)0.0205 (5)−0.0014 (4)0.0109 (4)0.0007 (4)
O20.0344 (6)0.0186 (5)0.0202 (5)−0.0044 (4)0.0076 (4)−0.0017 (4)
N10.0300 (8)0.0252 (7)0.0200 (6)−0.0044 (6)0.0085 (5)−0.0036 (5)
N20.0290 (7)0.0209 (6)0.0257 (6)−0.0012 (5)0.0103 (5)−0.0042 (5)
N30.0257 (7)0.0216 (6)0.0233 (6)−0.0008 (5)0.0083 (5)−0.0044 (5)
C10.0210 (7)0.0198 (7)0.0188 (6)0.0031 (6)0.0041 (5)0.0016 (5)
C20.0213 (7)0.0176 (7)0.0167 (6)0.0013 (5)0.0042 (5)0.0011 (5)
C30.0252 (8)0.0194 (7)0.0209 (6)−0.0029 (6)0.0063 (6)−0.0002 (5)
C40.0260 (8)0.0225 (7)0.0199 (6)−0.0033 (6)0.0095 (5)0.0018 (5)
C50.0215 (7)0.0214 (7)0.0178 (6)0.0029 (6)0.0033 (5)0.0004 (5)
C60.0216 (7)0.0186 (7)0.0222 (6)−0.0026 (6)0.0038 (5)−0.0010 (5)
C70.0208 (7)0.0197 (7)0.0215 (7)−0.0009 (6)0.0066 (5)0.0021 (5)
C80.0272 (8)0.0217 (7)0.0231 (7)0.0020 (6)0.0076 (6)−0.0020 (5)
C90.0305 (8)0.0281 (8)0.0247 (7)−0.0031 (6)0.0122 (6)−0.0021 (6)
C100.0308 (8)0.0244 (8)0.0269 (7)−0.0005 (6)0.0118 (6)0.0021 (6)

Geometric parameters (Å, °)

O1—C11.2987 (16)C2—C71.3964 (18)
O2—C11.2368 (16)C3—C41.3825 (18)
N1—C51.3858 (17)C3—H30.9500
N1—H1N0.94 (2)C4—C51.4016 (19)
N1—H2N0.89 (2)C4—H40.9500
N2—C81.3281 (17)C5—C61.397 (2)
N2—C91.3745 (19)C6—C71.3850 (18)
N2—H3N0.956 (19)C6—H60.9500
N3—C81.3200 (19)C7—H70.9500
N3—C101.3794 (18)C8—H80.9500
N3—H4N0.93 (2)C9—C101.349 (2)
C1—C21.4996 (18)C9—H90.9500
C2—C31.3900 (19)C10—H100.9500
C5—N1—H1N114.3 (12)C5—C4—H4119.7
C5—N1—H2N113.1 (12)N1—C5—C6121.89 (13)
H1N—N1—H2N115.1 (18)N1—C5—C4119.88 (13)
C8—N2—C9108.10 (12)C6—C5—C4118.19 (12)
C8—N2—H3N125.2 (12)C7—C6—C5120.69 (12)
C9—N2—H3N126.6 (12)C7—C6—H6119.7
C8—N3—C10108.23 (12)C5—C6—H6119.7
C8—N3—H4N125.5 (13)C6—C7—C2121.02 (13)
C10—N3—H4N125.7 (13)C6—C7—H7119.5
O2—C1—O1123.37 (12)C2—C7—H7119.5
O2—C1—C2119.86 (12)N3—C8—N2109.39 (13)
O1—C1—C2116.77 (12)N3—C8—H8125.3
C3—C2—C7118.20 (12)N2—C8—H8125.3
C3—C2—C1119.96 (12)C10—C9—N2107.24 (13)
C7—C2—C1121.83 (12)C10—C9—H9126.4
C4—C3—C2121.20 (13)N2—C9—H9126.4
C4—C3—H3119.4C9—C10—N3107.04 (13)
C2—C3—H3119.4C9—C10—H10126.5
C3—C4—C5120.68 (13)N3—C10—H10126.5
C3—C4—H4119.7
O2—C1—C2—C312.6 (2)C4—C5—C6—C7−1.1 (2)
O1—C1—C2—C3−167.05 (12)C5—C6—C7—C20.5 (2)
O2—C1—C2—C7−166.47 (12)C3—C2—C7—C60.2 (2)
O1—C1—C2—C713.89 (18)C1—C2—C7—C6179.26 (12)
C7—C2—C3—C4−0.2 (2)C10—N3—C8—N20.15 (16)
C1—C2—C3—C4−179.26 (12)C9—N2—C8—N3−0.43 (16)
C2—C3—C4—C5−0.5 (2)C8—N2—C9—C100.55 (17)
C3—C4—C5—N1178.96 (13)N2—C9—C10—N3−0.45 (17)
C3—C4—C5—C61.1 (2)C8—N3—C10—C90.19 (16)
N1—C5—C6—C7−178.90 (13)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N3—H4N···O1i0.93 (2)1.76 (2)2.6869 (15)171 (2)
N2—H3N···O1ii0.956 (19)1.742 (19)2.6938 (15)173.5 (19)
N1—H1N···O2iii0.94 (2)2.17 (2)2.9495 (16)139.3 (17)
N1—H2N···O1ii0.89 (2)2.20 (2)3.0149 (17)152.0 (16)
C6—H6···O2iv0.952.553.3533 (16)142

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x+1/2, −y+3/2, z−1/2; (iii) −x+1/2, y−1/2, −z+1/2; (iv) x−1/2, −y+3/2, z−1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2253).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Etter, M. (1990). Acc. Chem. Res. 23, 120–126.
  • Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.
  • Kopanska, K., Najda, A., Justyna, Z., Chomicz, L., Piekarczyk, J., Myja, P. & Bretner, M. (2004). Bioorg. Med. Chem. 12, 2617–2624. [PubMed]
  • Lai, T. F. & Marsh, R. E. (1967). Acta Cryst. 22, 885–893.
  • Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457.
  • McMullan, R. K., Epstein, J., Ruble, J. R. & Craven, B. M. (1979). Acta Cryst. B35, 688–691.
  • Moreno-Fuquen, R., De Almeida Santos, R. H. & Lechat, J. R. (1996). Acta Cryst. C52, 220–222.
  • Moreno-Fuquen, R., Ellena, J. & Theodoro, J. E. (2009). Acta Cryst. E65, o2717. [PMC free article] [PubMed]
  • Nardelli, M. (1995). J. Appl. Cryst. 28, 659.
  • Oxford Diffraction (2009). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.
  • Robinson, F. A. (1966). The Vitamin Co-factors of Enzyme Systems, pp. 541–662. London: Pergamon.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Sondhi, S. M., Rajvanshi, S., Johar, M., Bharti, N., Azam, A. & Singh, A. K. (2002). Eur. J. Med. Chem. 37, 835–843. [PubMed]

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography