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

Angevine, D.J.; Benedict, J.B.

doi:10.1107/S2414314622005107

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 7| Part 5| May 2022| x220510

https://doi.org/10.1107/S2414314622005107

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

Devin J. Angevine ^a and Jason B. Benedict ^a ^*

^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 π–π stacking interactions into a three-dimensional network. The anion features an intramolecular O—H⋯O hydrogen bond.

Keywords: crystal structure; organic co-crystal; vanillic acid; bipyridine ethylene.

CCDC reference: 2172156

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 ). 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 ; Wang et al., 2007 ). In addition, as the ΔpK_a value between o-vanillic acid (pK_a = 2.5) and bipyridine ethylene (pK_a = 5.5) is approximately 3, the observed salt formation can reasonably be expected due to the acid–base crystalline complexes ΔpK_a rule (Cruz-Cabeza, 2012 ).

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, Table 1). These trimolecular units (Fig. 2) then stack through aromatic π–π 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 and 4). The stacks then sit aside of an alternating stack of units and are cross-linked through C—H⋯O type hydrogen bonds (Fig. 5). When viewed down [101], the slipped stacks can be seen running along [101], with alternating domains parallel to [010] (Fig. 6).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	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) ; (ii) .

Figure 1
The asymmetric unit of the title molecular salt showing 50% displacement ellipsoids.

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
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
Top down view of the π-stacked trimolecular units. Offset units are shown in different colors.

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
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.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₂H₁₂N₂²⁺·2C₈H₇O₄⁻
M_r	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)
V (Å³)	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 )
T_min, T_max	0.552, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	20958, 3650, 2905
R_int	0.066
(sin θ/λ)_max (Å⁻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
Δρ_max, Δρ_min (e Å⁻³)	0.53, −0.22
Computer programs: APEX2 and SAINT (Bruker, 2016), olex2.solve (Bourhis et al., 2015 ), SHELXL (Sheldrick, 2008 ), and OLEX2 (Dolomanov et al., 2009 ).

Structural data

CCDC reference: 2172156

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314622005107/hb4406sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314622005107/hb4406Isup2.hkl

checkCIF report

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⁺·2C₈H₇O₄⁻	F(000) = 544
M_r = 518.51	D_x = 1.391 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.543 (2) Å	Cell parameters from 4917 reflections
b = 20.729 (5) Å	θ = 2.6–30.2°
c = 7.7061 (17) Å	µ = 0.10 mm⁻¹
β = 114.898 (4)°	T = 90 K
V = 1237.8 (5) Å³	Plate, clear colourless
Z = 2	0.58 × 0.25 × 0.02 mm

Data collection top

Bruker APEXII CCD diffractometer	2905 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.066
Absorption correction: multi-scan (SADABS; Bruker, 2016)	θ_max = 30.2°, θ_min = 2.0°
T_min = 0.552, T_max = 0.746	h = −11→12
20958 measured reflections	k = −29→29
3650 independent reflections	l = −10→10

Refinement top

Refinement on F²	Primary atom site location: iterative
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.047	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.132	w = 1/[σ²(F_o²) + (0.0606P)² + 0.4983P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max < 0.001
3650 reflections	Δρ_max = 0.53 e Å⁻³
181 parameters	Δρ_min = −0.22 e Å⁻³
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 U_iso(H) = 1.2U_eq(C).

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

	x	y	z	U_iso*/U_eq
O2	0.24089 (12)	0.42238 (4)	0.25115 (13)	0.0198 (2)
O3	0.56630 (12)	0.41986 (5)	0.42339 (13)	0.0225 (2)
O1	−0.04982 (12)	0.36590 (4)	0.01841 (14)	0.0217 (2)
O4	0.71834 (12)	0.35219 (5)	0.32767 (15)	0.0254 (2)
N1	−0.02080 (14)	0.41143 (5)	−0.43034 (15)	0.0171 (2)
C6	0.41360 (15)	0.34659 (6)	0.17054 (16)	0.0147 (2)
C7	0.25353 (15)	0.37113 (5)	0.14897 (16)	0.0145 (2)
C2	0.09975 (15)	0.34088 (6)	0.02102 (17)	0.0158 (2)
C11	0.26852 (16)	0.47304 (6)	−0.16647 (17)	0.0173 (2)
C8	0.57618 (16)	0.37522 (6)	0.31710 (17)	0.0175 (2)
C5	0.41996 (16)	0.29391 (6)	0.06001 (18)	0.0185 (2)
H5	0.528263	0.277301	0.073926	0.022*
C13	−0.03901 (16)	0.45885 (6)	−0.32230 (18)	0.0179 (2)
H13	−0.151365	0.470811	−0.337355	0.022*
C9	0.13651 (17)	0.39427 (6)	−0.41449 (18)	0.0194 (2)
H9	0.146696	0.360930	−0.493684	0.023*
C3	0.10839 (16)	0.28915 (6)	−0.08833 (18)	0.0190 (2)
H3	0.005280	0.269293	−0.176397	0.023*
C14	0.41779 (16)	0.50517 (6)	−0.01775 (18)	0.0198 (2)
H14	0.395078	0.536024	0.059892	0.024*
C12	0.10275 (16)	0.49066 (6)	−0.18939 (18)	0.0188 (2)
H12	0.087893	0.524298	−0.113955	0.023*
C10	0.28331 (16)	0.42435 (6)	−0.28499 (18)	0.0194 (2)
H10	0.393602	0.412167	−0.276192	0.023*
C4	0.26890 (17)	0.26605 (6)	−0.06931 (18)	0.0207 (3)
H4	0.273946	0.230930	−0.145981	0.025*
C1	−0.20613 (18)	0.33220 (7)	−0.0933 (2)	0.0270 (3)
H1A	−0.233819	0.337474	−0.229464	0.041*
H1B	−0.300275	0.349769	−0.066656	0.041*
H1C	−0.191431	0.286266	−0.060228	0.041*
H2	0.357 (3)	0.4327 (11)	0.340 (3)	0.055 (6)*
H1	−0.131 (3)	0.3851 (10)	−0.532 (3)	0.056 (6)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O2	0.0201 (5)	0.0218 (4)	0.0187 (4)	−0.0005 (3)	0.0094 (4)	−0.0056 (3)
O3	0.0197 (5)	0.0270 (5)	0.0186 (4)	−0.0036 (4)	0.0060 (4)	−0.0076 (4)
O1	0.0138 (4)	0.0248 (5)	0.0271 (5)	−0.0010 (3)	0.0092 (4)	−0.0032 (4)
O4	0.0142 (4)	0.0300 (5)	0.0291 (5)	−0.0030 (4)	0.0063 (4)	−0.0096 (4)
N1	0.0155 (5)	0.0192 (5)	0.0148 (5)	−0.0025 (4)	0.0047 (4)	0.0013 (4)
C6	0.0138 (5)	0.0171 (5)	0.0130 (5)	−0.0019 (4)	0.0055 (4)	0.0002 (4)
C7	0.0163 (5)	0.0159 (5)	0.0123 (5)	−0.0012 (4)	0.0068 (4)	0.0005 (4)
C2	0.0144 (5)	0.0185 (5)	0.0150 (5)	0.0002 (4)	0.0067 (4)	0.0022 (4)
C11	0.0168 (6)	0.0190 (5)	0.0144 (5)	−0.0017 (4)	0.0049 (4)	0.0029 (4)
C8	0.0160 (6)	0.0205 (6)	0.0150 (5)	−0.0035 (4)	0.0056 (4)	0.0002 (4)
C5	0.0162 (6)	0.0202 (6)	0.0195 (6)	0.0001 (4)	0.0080 (5)	−0.0016 (4)
C13	0.0163 (6)	0.0192 (5)	0.0177 (6)	0.0010 (4)	0.0066 (5)	0.0026 (4)
C9	0.0193 (6)	0.0223 (6)	0.0176 (6)	−0.0007 (5)	0.0088 (5)	−0.0008 (4)
C3	0.0163 (6)	0.0214 (6)	0.0170 (6)	−0.0031 (4)	0.0046 (5)	−0.0021 (4)
C14	0.0189 (6)	0.0209 (6)	0.0190 (6)	−0.0017 (4)	0.0074 (5)	−0.0016 (5)
C12	0.0183 (6)	0.0186 (5)	0.0186 (6)	−0.0010 (4)	0.0070 (5)	−0.0002 (4)
C10	0.0153 (6)	0.0242 (6)	0.0194 (6)	−0.0002 (4)	0.0079 (5)	0.0010 (5)
C4	0.0213 (6)	0.0204 (6)	0.0207 (6)	−0.0021 (5)	0.0092 (5)	−0.0063 (5)
C1	0.0159 (6)	0.0304 (7)	0.0335 (7)	−0.0028 (5)	0.0090 (6)	−0.0009 (6)

Geometric parameters (Å, º) top

O2—C7	1.3535 (14)	C5—H5	0.9500
O2—H2	0.96 (2)	C5—C4	1.3818 (18)
O3—C8	1.2618 (15)	C13—H13	0.9500
O1—C2	1.3713 (15)	C13—C12	1.3806 (17)
O1—C1	1.4297 (16)	C9—H9	0.9500
O4—C8	1.2753 (16)	C9—C10	1.3797 (18)
N1—C13	1.3389 (16)	C3—H3	0.9500
N1—C9	1.3451 (17)	C3—C4	1.4005 (18)
N1—H1	1.09 (2)	C14—C14ⁱ	1.330 (3)
C6—C7	1.4018 (16)	C14—H14	0.9500
C6—C8	1.4954 (16)	C12—H12	0.9500
C6—C5	1.3999 (16)	C10—H10	0.9500
C7—C2	1.4144 (17)	C4—H4	0.9500
C2—C3	1.3849 (17)	C1—H1A	0.9800
C11—C14	1.4672 (17)	C1—H1B	0.9800
C11—C12	1.3998 (18)	C1—H1C	0.9800
C11—C10	1.4020 (17)

C7—O2—H2	105.9 (13)	C12—C13—H13	119.4
C2—O1—C1	116.90 (10)	N1—C9—H9	119.5
C13—N1—C9	120.72 (11)	N1—C9—C10	121.02 (11)
C13—N1—H1	121.6 (12)	C10—C9—H9	119.5
C9—N1—H1	117.7 (12)	C2—C3—H3	119.9
C7—C6—C8	119.67 (10)	C2—C3—C4	120.11 (11)
C5—C6—C7	119.79 (11)	C4—C3—H3	119.9
C5—C6—C8	120.50 (11)	C11—C14—H14	117.2
O2—C7—C6	121.91 (10)	C14ⁱ—C14—C11	125.64 (15)
O2—C7—C2	118.38 (10)	C14ⁱ—C14—H14	117.2
C6—C7—C2	119.68 (11)	C11—C12—H12	120.2
O1—C2—C7	115.39 (10)	C13—C12—C11	119.60 (12)
O1—C2—C3	124.89 (11)	C13—C12—H12	120.2
C3—C2—C7	119.71 (11)	C11—C10—H10	120.2
C12—C11—C14	118.72 (11)	C9—C10—C11	119.52 (11)
C12—C11—C10	118.00 (11)	C9—C10—H10	120.2
C10—C11—C14	123.27 (11)	C5—C4—C3	120.57 (12)
O3—C8—O4	123.73 (11)	C5—C4—H4	119.7
O3—C8—C6	119.12 (11)	C3—C4—H4	119.7
O4—C8—C6	117.15 (11)	O1—C1—H1A	109.5
C6—C5—H5	120.0	O1—C1—H1B	109.5
C4—C5—C6	120.07 (11)	O1—C1—H1C	109.5
C4—C5—H5	120.0	H1A—C1—H1B	109.5
N1—C13—H13	119.4	H1A—C1—H1C	109.5
N1—C13—C12	121.11 (11)	H1B—C1—H1C	109.5

O2—C7—C2—O1	−2.15 (15)	C8—C6—C5—C4	177.25 (11)
O2—C7—C2—C3	178.70 (11)	C5—C6—C7—O2	−179.29 (11)
O1—C2—C3—C4	−177.73 (11)	C5—C6—C7—C2	2.46 (17)
N1—C13—C12—C11	−0.18 (18)	C5—C6—C8—O3	−175.32 (11)
N1—C9—C10—C11	0.76 (18)	C5—C6—C8—O4	4.15 (17)
C6—C7—C2—O1	176.16 (10)	C13—N1—C9—C10	0.90 (18)
C6—C7—C2—C3	−2.99 (17)	C9—N1—C13—C12	−1.20 (18)
C6—C5—C4—C3	−1.40 (19)	C14—C11—C12—C13	−176.93 (11)
C7—C6—C8—O3	2.21 (17)	C14—C11—C10—C9	176.58 (11)
C7—C6—C8—O4	−178.32 (11)	C12—C11—C14—C14ⁱ	−178.18 (16)
C7—C6—C5—C4	−0.28 (18)	C12—C11—C10—C9	−2.06 (18)
C7—C2—C3—C4	1.34 (18)	C10—C11—C14—C14ⁱ	3.2 (2)
C2—C3—C4—C5	0.9 (2)	C10—C11—C12—C13	1.78 (18)
C8—C6—C7—O2	3.16 (17)	C1—O1—C2—C7	−173.35 (11)
C8—C6—C7—C2	−175.09 (10)	C1—O1—C2—C3	5.75 (18)

Symmetry code: (i) −x+1, −y+1, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4ⁱⁱ	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···O2ⁱⁱⁱ	0.95	2.52	3.1831 (16)	127
C13—H13···O3ⁱⁱ	0.95	2.57	3.2092 (17)	125
C12—H12···O1ⁱⁱⁱ	0.95	2.46	3.3591 (17)	159

Symmetry codes: (ii) x−1, y, z−1; (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).

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