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4,4'-(Ethene-1,2-diyl)dipyridinium bis­(2-hy­dr­oxy-3-meth­­oxy­benzoate)

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aDepartment of Chemistry, The State University of New York at Buffalo, Buffalo, New York 14260-3000, USA
*Correspondence e-mail: jbb6@buffalo.edu

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 30 March 2022; accepted 11 May 2022; online 17 May 2022)

In the title double proton-transfer salt, C12H12N22+·2C8H7O4, consisting of a 1:2 ratio of 4,4'-(ethene-1,2-diyl)dipyridinium cations (trans bipyridinium ethyl­ene) to 2-hy­droxy-3-meth­oxy­benzoate anions (o-vanillate), the complete cation is generated by crystallographic inversion symmetry and it is linked to adjacent o-vanillate anions by N—H⋯O hydrogen bonds, forming trimolecular assemblies. The trimers are linked by C—H⋯O hydrogen bonds as well as aromatic ππ stacking inter­actions into a three-dimensional network. The anion features an intra­molecular O—H⋯O hydrogen bond.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

2-Hy­droxy-3-meth­oxy­benzoic acid (o-vanillic acid, C7H8O4) is similar in nature to its isomeric counterpart 4-hy­droxy-3-meth­oxy­benzoic acid (p-vanillic acid), with the exception of the hydroxyl-group positioning. Much like its counterpart, o-vanillic acid is being investigated for its medicinal benefits, such as its anti-allergic inflammatory effects (Kim et al., 2017[Kim, Y.-Y., Je, I.-G., Kim, M. J., Kang, B.-C., Choi, Y.-A., Baek, M.-C., Lee, B., Choi, J. K., Park, H. R., Shin, T.-Y., Lee, S., Yoon, S.-B., Lee, S.-R., Khang, D. & Kim, S.-H. (2017). Acta Pharmacol. Sin. 38, 90-99.]). Despite its potential usage for medicinal purposes, there is a significant lack of structural data on this compound and its salts. As such it is beneficial to study the solid-state forms of o-vanillic acid and its salts to better understand its inter­actions. To achieve this, bi­pyridine ethyl­ene (C12H10N2) was selected due to its demonstrated ability to form both simple and complex hydrogen-bonded networks (MacGillivray et al., 2000[MacGillivray, L. R., Reid, J. L. & Ripmeester, J. A. (2000). J. Am. Chem. Soc. 122, 7817-7818.]; Wang et al., 2007[Wang, J., Ding, L. & Yang, C. (2007). CrystEngComm, 9, 591-594.]). In addition, as the ΔpKa value between o-vanillic acid (pKa = 2.5) and bi­pyridine ethyl­ene (pKa = 5.5) is approximately 3, the observed salt formation can reasonably be expected due to the acid–base crystalline complexes ΔpKa rule (Cruz-Cabeza, 2012[Cruz-Cabeza, A. J. (2012). CrystEngComm, 14, 6362-6365.]).

The structure of the resulting bipyridinium ethyl­ene bis-o-vanillate mol­ecular salt, C12H12N22+·2C8H7O4, exhibits monoclinic (P21/c) symmetry at 90 K: the complete cation is generated by crystallographic inversion symmetry. A trimolecular unit consisting of one bipyridinium ethyl­ene cation (BPyE) with two o-vanillate anions, each of which accepts an N1—H1⋯O4 hydrogen bond from the pyridinium N atoms of the cation is observed, in which the H1⋯O4 distance of 1.45 (2) Å and the N1⋯O4 separation of 2.5402 (15) Å are notably short. The cation–anion bonding is consolidated by a C13—H13⋯O3 link and within the anion, an S(6) intra­molecular O2—H2⋯O3 hydrogen bond is observed between the hydroxyl group and the O atom of the carboxyl group (Fig. 1[link], Table 1[link]). These trimolecular units (Fig. 2[link]) then stack through aromatic ππ inter­actions [shortest centroid–centroid separation = 3.5125 (11) Å between the N1/C9–C13 and C2–C7 rings] with an approximately one third unit offset (Figs. 3[link] and 4[link]). The stacks then sit aside of an alternating stack of units and are cross-linked through C—H⋯O type hydrogen bonds (Fig. 5[link]). When viewed down [101], the slipped stacks can be seen running along [101], with alternating domains parallel to [010] (Fig. 6[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯O4i 1.09 (2) 1.45 (2) 2.5402 (15) 178 (2)
O2—H2⋯O3 0.96 (2) 1.64 (2) 2.5270 (14) 150 (2)
C13—H13⋯O2ii 0.95 2.52 3.1831 (16) 127
C13—H13⋯O3i 0.95 2.57 3.2092 (17) 125
C12—H12⋯O1ii 0.95 2.46 3.3591 (17) 159
Symmetry codes: (i) [x-1, y, z-1]; (ii) [-x, -y+1, -z].
[Figure 1]
Figure 1
The asymmetric unit of the title mol­ecular salt showing 50% displacement ellipsoids.
[Figure 2]
Figure 2
A trimolecular unit of the synthesized salt consisting of two o-vanillate anions and one bipyridinium ethyl­ene cation. Hydrogen-bonding inter­actions are shown as red dashed lines with distances displayed between inter­acting heteroatoms.
[Figure 3]
Figure 3
Side on view of the π-stacked trimolecular units. Offset units are shown in different colors. Distances, in Å, are shown between inter­acting ring centroids.
[Figure 4]
Figure 4
Top down view of the π-stacked trimolecular units. Offset units are shown in different colors.
[Figure 5]
Figure 5
A single layer of the side by side trimolecular unit inter­actions are shown. Hydrogen-bonding inter­actions are shown as dashed blue lines; C—H⋯O type hydrogen-bonding inter­actions are shown as solid green lines.
[Figure 6]
Figure 6
View down [101] showing slipped stacks running along [101] with alternating domains parallel to [010] being highlighted in pink and blue. Hydrogen-bonding inter­actions are shown as blue dashed lines.

Synthesis and crystallization

A 1:2 molar ratio of bi­pyridine ethyl­ene (182.2 mg, 1 mmol) and o-vanillic acid (336.2 mg, 2 mmol) were dissolved into a vial of excess methanol. The resulting solution was vortexed for 30 s at 3,000 rpm on a VWR Mini Vortexer MV I. The solution was then stored in the dark uncapped to allow for crystal formation while the solvent slowly evaporated.

Refinement

Crystal data, data collection, and structure refinement details are summarized in Table 2[link].

Table 2
Experimental details

Crystal data
Chemical formula C12H12N22+·2C8H7O4
Mr 518.51
Crystal system, space group Monoclinic, P21/c
Temperature (K) 90
a, b, c (Å) 8.543 (2), 20.729 (5), 7.7061 (17)
β (°) 114.898 (4)
V3) 1237.8 (5)
Z 2
Radiation type Mo Kα
μ (mm−1) 0.10
Crystal size (mm) 0.58 × 0.25 × 0.02
 
Data collection
Diffractometer Bruker APEXII CCD
Absorption correction Multi-scan (SADABS; Bruker, 2016[Bruker (2016). APEX2, SADABS and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.552, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 20958, 3650, 2905
Rint 0.066
(sin θ/λ)max−1) 0.708
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.047, 0.132, 1.03
No. of reflections 3650
No. of parameters 181
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.53, −0.22
Computer programs: APEX2 and SAINT (Bruker, 2016[Bruker (2016). APEX2, SADABS and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), olex2.solve (Bourhis et al., 2015[Bourhis, L. J., Dolomanov, O. V., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2015). Acta Cryst. A71, 59-75.]), SHELXL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

Structural data


Computing details top

Data collection: APEXII (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: olex2.solve (Bourhis et al., 2015); program(s) used to refine structure: SHELXL (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

4,4'-(Ethene-1,2-diyl)dipyridinium bis(2-hydroxy-3-methoxybenzoate) top
Crystal data top
C12H12N22+·2C8H7O4F(000) = 544
Mr = 518.51Dx = 1.391 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 8.543 (2) ÅCell parameters from 4917 reflections
b = 20.729 (5) Åθ = 2.6–30.2°
c = 7.7061 (17) ŵ = 0.10 mm1
β = 114.898 (4)°T = 90 K
V = 1237.8 (5) Å3Plate, clear colourless
Z = 20.58 × 0.25 × 0.02 mm
Data collection top
Bruker APEXII CCD
diffractometer
2905 reflections with I > 2σ(I)
φ and ω scansRint = 0.066
Absorption correction: multi-scan
(SADABS; Bruker, 2016)
θmax = 30.2°, θmin = 2.0°
Tmin = 0.552, Tmax = 0.746h = 1112
20958 measured reflectionsk = 2929
3650 independent reflectionsl = 1010
Refinement top
Refinement on F2Primary atom site location: iterative
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.047H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.132 w = 1/[σ2(Fo2) + (0.0606P)2 + 0.4983P]
where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max < 0.001
3650 reflectionsΔρmax = 0.53 e Å3
181 parametersΔρmin = 0.22 e Å3
0 restraints
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. H atoms attached to heteroatoms were freely refined isotropically. H atoms connected to carbon atoms were placed geometrically (C—H = 0.95 Å) and refined as riding atoms with Uiso(H) = 1.2Ueq(C).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O20.24089 (12)0.42238 (4)0.25115 (13)0.0198 (2)
O30.56630 (12)0.41986 (5)0.42339 (13)0.0225 (2)
O10.04982 (12)0.36590 (4)0.01841 (14)0.0217 (2)
O40.71834 (12)0.35219 (5)0.32767 (15)0.0254 (2)
N10.02080 (14)0.41143 (5)0.43034 (15)0.0171 (2)
C60.41360 (15)0.34659 (6)0.17054 (16)0.0147 (2)
C70.25353 (15)0.37113 (5)0.14897 (16)0.0145 (2)
C20.09975 (15)0.34088 (6)0.02102 (17)0.0158 (2)
C110.26852 (16)0.47304 (6)0.16647 (17)0.0173 (2)
C80.57618 (16)0.37522 (6)0.31710 (17)0.0175 (2)
C50.41996 (16)0.29391 (6)0.06001 (18)0.0185 (2)
H50.5282630.2773010.0739260.022*
C130.03901 (16)0.45885 (6)0.32230 (18)0.0179 (2)
H130.1513650.4708110.3373550.022*
C90.13651 (17)0.39427 (6)0.41449 (18)0.0194 (2)
H90.1466960.3609300.4936840.023*
C30.10839 (16)0.28915 (6)0.08833 (18)0.0190 (2)
H30.0052800.2692930.1763970.023*
C140.41779 (16)0.50517 (6)0.01775 (18)0.0198 (2)
H140.3950780.5360240.0598920.024*
C120.10275 (16)0.49066 (6)0.18939 (18)0.0188 (2)
H120.0878930.5242980.1139550.023*
C100.28331 (16)0.42435 (6)0.28499 (18)0.0194 (2)
H100.3936020.4121670.2761920.023*
C40.26890 (17)0.26605 (6)0.06931 (18)0.0207 (3)
H40.2739460.2309300.1459810.025*
C10.20613 (18)0.33220 (7)0.0933 (2)0.0270 (3)
H1A0.2338190.3374740.2294640.041*
H1B0.3002750.3497690.0666560.041*
H1C0.1914310.2862660.0602280.041*
H20.357 (3)0.4327 (11)0.340 (3)0.055 (6)*
H10.131 (3)0.3851 (10)0.532 (3)0.056 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O20.0201 (5)0.0218 (4)0.0187 (4)0.0005 (3)0.0094 (4)0.0056 (3)
O30.0197 (5)0.0270 (5)0.0186 (4)0.0036 (4)0.0060 (4)0.0076 (4)
O10.0138 (4)0.0248 (5)0.0271 (5)0.0010 (3)0.0092 (4)0.0032 (4)
O40.0142 (4)0.0300 (5)0.0291 (5)0.0030 (4)0.0063 (4)0.0096 (4)
N10.0155 (5)0.0192 (5)0.0148 (5)0.0025 (4)0.0047 (4)0.0013 (4)
C60.0138 (5)0.0171 (5)0.0130 (5)0.0019 (4)0.0055 (4)0.0002 (4)
C70.0163 (5)0.0159 (5)0.0123 (5)0.0012 (4)0.0068 (4)0.0005 (4)
C20.0144 (5)0.0185 (5)0.0150 (5)0.0002 (4)0.0067 (4)0.0022 (4)
C110.0168 (6)0.0190 (5)0.0144 (5)0.0017 (4)0.0049 (4)0.0029 (4)
C80.0160 (6)0.0205 (6)0.0150 (5)0.0035 (4)0.0056 (4)0.0002 (4)
C50.0162 (6)0.0202 (6)0.0195 (6)0.0001 (4)0.0080 (5)0.0016 (4)
C130.0163 (6)0.0192 (5)0.0177 (6)0.0010 (4)0.0066 (5)0.0026 (4)
C90.0193 (6)0.0223 (6)0.0176 (6)0.0007 (5)0.0088 (5)0.0008 (4)
C30.0163 (6)0.0214 (6)0.0170 (6)0.0031 (4)0.0046 (5)0.0021 (4)
C140.0189 (6)0.0209 (6)0.0190 (6)0.0017 (4)0.0074 (5)0.0016 (5)
C120.0183 (6)0.0186 (5)0.0186 (6)0.0010 (4)0.0070 (5)0.0002 (4)
C100.0153 (6)0.0242 (6)0.0194 (6)0.0002 (4)0.0079 (5)0.0010 (5)
C40.0213 (6)0.0204 (6)0.0207 (6)0.0021 (5)0.0092 (5)0.0063 (5)
C10.0159 (6)0.0304 (7)0.0335 (7)0.0028 (5)0.0090 (6)0.0009 (6)
Geometric parameters (Å, º) top
O2—C71.3535 (14)C5—H50.9500
O2—H20.96 (2)C5—C41.3818 (18)
O3—C81.2618 (15)C13—H130.9500
O1—C21.3713 (15)C13—C121.3806 (17)
O1—C11.4297 (16)C9—H90.9500
O4—C81.2753 (16)C9—C101.3797 (18)
N1—C131.3389 (16)C3—H30.9500
N1—C91.3451 (17)C3—C41.4005 (18)
N1—H11.09 (2)C14—C14i1.330 (3)
C6—C71.4018 (16)C14—H140.9500
C6—C81.4954 (16)C12—H120.9500
C6—C51.3999 (16)C10—H100.9500
C7—C21.4144 (17)C4—H40.9500
C2—C31.3849 (17)C1—H1A0.9800
C11—C141.4672 (17)C1—H1B0.9800
C11—C121.3998 (18)C1—H1C0.9800
C11—C101.4020 (17)
C7—O2—H2105.9 (13)C12—C13—H13119.4
C2—O1—C1116.90 (10)N1—C9—H9119.5
C13—N1—C9120.72 (11)N1—C9—C10121.02 (11)
C13—N1—H1121.6 (12)C10—C9—H9119.5
C9—N1—H1117.7 (12)C2—C3—H3119.9
C7—C6—C8119.67 (10)C2—C3—C4120.11 (11)
C5—C6—C7119.79 (11)C4—C3—H3119.9
C5—C6—C8120.50 (11)C11—C14—H14117.2
O2—C7—C6121.91 (10)C14i—C14—C11125.64 (15)
O2—C7—C2118.38 (10)C14i—C14—H14117.2
C6—C7—C2119.68 (11)C11—C12—H12120.2
O1—C2—C7115.39 (10)C13—C12—C11119.60 (12)
O1—C2—C3124.89 (11)C13—C12—H12120.2
C3—C2—C7119.71 (11)C11—C10—H10120.2
C12—C11—C14118.72 (11)C9—C10—C11119.52 (11)
C12—C11—C10118.00 (11)C9—C10—H10120.2
C10—C11—C14123.27 (11)C5—C4—C3120.57 (12)
O3—C8—O4123.73 (11)C5—C4—H4119.7
O3—C8—C6119.12 (11)C3—C4—H4119.7
O4—C8—C6117.15 (11)O1—C1—H1A109.5
C6—C5—H5120.0O1—C1—H1B109.5
C4—C5—C6120.07 (11)O1—C1—H1C109.5
C4—C5—H5120.0H1A—C1—H1B109.5
N1—C13—H13119.4H1A—C1—H1C109.5
N1—C13—C12121.11 (11)H1B—C1—H1C109.5
O2—C7—C2—O12.15 (15)C8—C6—C5—C4177.25 (11)
O2—C7—C2—C3178.70 (11)C5—C6—C7—O2179.29 (11)
O1—C2—C3—C4177.73 (11)C5—C6—C7—C22.46 (17)
N1—C13—C12—C110.18 (18)C5—C6—C8—O3175.32 (11)
N1—C9—C10—C110.76 (18)C5—C6—C8—O44.15 (17)
C6—C7—C2—O1176.16 (10)C13—N1—C9—C100.90 (18)
C6—C7—C2—C32.99 (17)C9—N1—C13—C121.20 (18)
C6—C5—C4—C31.40 (19)C14—C11—C12—C13176.93 (11)
C7—C6—C8—O32.21 (17)C14—C11—C10—C9176.58 (11)
C7—C6—C8—O4178.32 (11)C12—C11—C14—C14i178.18 (16)
C7—C6—C5—C40.28 (18)C12—C11—C10—C92.06 (18)
C7—C2—C3—C41.34 (18)C10—C11—C14—C14i3.2 (2)
C2—C3—C4—C50.9 (2)C10—C11—C12—C131.78 (18)
C8—C6—C7—O23.16 (17)C1—O1—C2—C7173.35 (11)
C8—C6—C7—C2175.09 (10)C1—O1—C2—C35.75 (18)
Symmetry code: (i) x+1, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O4ii1.09 (2)1.45 (2)2.5402 (15)178 (2)
O2—H2···O30.96 (2)1.64 (2)2.5270 (14)150 (2)
C13—H13···O2iii0.952.523.1831 (16)127
C13—H13···O3ii0.952.573.2092 (17)125
C12—H12···O1iii0.952.463.3591 (17)159
Symmetry codes: (ii) x1, y, z1; (iii) x, y+1, z.
 

Funding information

Funding for this research was provided by: National Science Foundation, Directorate for Mathematical and Physical Sciences (award No. DMR-2003932).

References

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