Diphenic acid–4,4′-bi­pyridine (2/1)

In the title co-crystal, 2C₁₄H₁₀O₄·C₁₀H₈N₂, the diphenic acid mol­ecules form a centrosymmetric dimeric pair, through strong O—H...O hydrogen bonds involving a carboxyl­ic acid group from each mol­ecule. In the crystal structure, the dimers are linked by C—H...O interactions to form layers parallel to the (001) plane. The adjacent layers are interlinked by bi­pyridine mol­ecules, C₁₀H₈N₂, through O—H...N hydrogen bonds. The bipyridine molecule lies on a centre of symmetry.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.036
• wR factor = 0.054
• Data-to-parameter ratio = 12.6

checkCIF results

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S1. Comment

The binding properties of the carboxyl groups of benzoic acid and its derivatives are interesting themes of structural chemistry (Lam et al., 2003). The diphenic acid (biphenyl-2,2'-dicarboxylic acid) is an extremely versatile building block for the purposes of crystal engineering. In the crystal structure of this compound, molecules form infinite chains, via R₂²(8) carboxylic acid pairs (Fronczek et al., 1987). The co-crystal structure of diphenic acid, diphenic acid-acridine (1/1) has been reported (Shaameri et al., 2001). Herein, we report the co-crystal structure of diphenic acid-4,4'-bipyridine (2/1), (I), which comprises two acid and one base molecule.

The asymmetric unit of (I) consists of one molecule of diphenic acid and a half molecule of 4,4'-bipyridine. The other diphenic acid molecule and the other half of the bipyridine molecule are generated by the symmetry operations (2 − x, 1 − y, −z) and (1 − x, 2 − y, 1 − z), respectively. In the diphenic acid, one of the carboxylic acid group shows normal C—O distances [O1—C1 = 1.321 (3) and O2—C1 = 1.197 (3) Å], while in the other these distances are nearly equal [C14—O3 = 1.272 (2) and C14—O4 = 1.256 (2) Å] indicating that it exists as COO⁻ ion. However, no proton transfer from this carboxylic acid group to a N atom of the bipyridine is observed. Instead, the H⁺ ion is located at a distance of 1.33 (4) Å from O3 and 1.29 (4) Å from O4ⁱ indicating the formation of centrosymmetric diphenic acid dimer through strong O—H···O hydrogen bonds (Table 2). The dimers are linked through C4—H4···O2ⁱⁱⁱ and C6—H6···O3^iv interactions to form molecular layers parallel to the (0 0 1) plane. The adjacent layers are interlinked by the bipyridine molecules through O1—H1···N1ⁱⁱ hydrogen bonds. The symmetry codes are given in Table 2.

S2. Experimental

Diphenic acid and 4,4'-bipyridine were obtained from Aldrich. Equimolar quantities of diphenic acid (27 mg) and 4,4'-bipyridine (15 mg) were dissolved in 15 ml of ethanol. The resulting solution was then set aside to crystallize at room temperature.

S3. Refinement

The C-bound H atoms were placed at their geometrically calculated positions, with C—H = 0.95 Å and in the riding model with U_iso(H) = 1.2U_eq(C). Attempts to place H2 at the calculated position resulted in a non-planar R₂²(8) ring formation, with an O—H···O angle of 133°. Hence, H1 and H2 were located from a difference Fourier map and both positional and isotropic displacement parameters were refined. H2 is involved in nearly symmetrical O—H···O hydrogen bonds with O···H distances of 1.33 (4) and 1.29 (4) Å, respectively.

Computing details

Data collection: AFC Diffractometer Control (Molecular Structure Corporation, 1992); cell refinement: AFC Diffractometer Control; data reduction: TEXSAN (Molecular Structure Corporation, 1992); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

Figures

	Fig. 1. The structure of (I), showing 50% probability displacement ellipsoids and the atom-numbering scheme for one asymmetric unit. The other diphenic acid molecule and the other half of the bipyridine molecule are generated by the crystallographic inversion centres.
	Fig. 2. Molecular packing of (I), viewed down the a axis.

(I)

Crystal data

C28H20O8·C10H8N2	Z = 1
Mr = 640.62	F(000) = 334.00
Triclinic, P1	Dx = 1.326 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.7107 Å
a = 6.498 (2) Å	Cell parameters from 25 reflections
b = 8.002 (7) Å	θ = 13.2–16.3°
c = 16.208 (6) Å	µ = 0.09 mm^−1
α = 99.45 (5)°	T = 298 K
β = 100.93 (3)°	Block, colourless
γ = 98.42 (5)°	0.44 × 0.32 × 0.28 mm
V = 802.4 (8) Å^3

Data collection

AFC7R diffractometer	1448 reflections with I > 2σ(I)
Radiation source: X-ray tube	Rint = 0.016
Graphite monochromator	θmax = 25.0°, θmin = 2.2°
ω/2–θ scans	h = −7→7
Absorption correction: ψ scan (North et al., 1968)	k = 0→9
Tmin = 0.957, Tmax = 0.996	l = −19→18
3049 measured reflections	3 standard reflections every 250 reflections
2830 independent reflections	intensity decay: −0.9%

Refinement

Refinement on F	0 restraints
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.036	Weighting scheme based on measured s.u.'s w = 1/[(σ)^2(Fo) + 0.00016(Fo)^2]
wR(F^2) = 0.054	(Δ/σ)max < 0.001
S = 1.31	Δρmax = 0.30 e Å^−3
2830 reflections	Δρmin = −0.27 e Å^−3
225 parameters

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

	x	y	z	Uiso*/Ueq
O1	1.1226 (3)	0.6029 (2)	0.3652 (1)	0.0703 (6)
O2	0.8605 (3)	0.4039 (2)	0.2836 (1)	0.0895 (7)
O3	0.8094 (3)	0.3251 (2)	−0.0025 (1)	0.0666 (6)
O4	0.8892 (3)	0.5837 (2)	0.0816 (1)	0.0651 (6)
N1	0.7048 (4)	0.6498 (3)	0.5733 (1)	0.0713 (8)
C1	0.9452 (4)	0.5522 (3)	0.3054 (1)	0.0495 (7)
C2	0.8630 (3)	0.6970 (3)	0.2711 (1)	0.0431 (6)
C3	0.9730 (4)	0.8641 (3)	0.3042 (1)	0.0557 (7)
C4	0.8981 (4)	1.0036 (3)	0.2778 (2)	0.0650 (8)
C5	0.7092 (5)	0.9766 (3)	0.2186 (2)	0.0663 (9)
C6	0.5989 (4)	0.8119 (3)	0.1844 (1)	0.0566 (7)
C7	0.6748 (3)	0.6686 (3)	0.2078 (1)	0.0430 (6)
C8	0.5456 (3)	0.4946 (3)	0.1649 (1)	0.0449 (6)
C9	0.3618 (4)	0.4401 (3)	0.1923 (1)	0.0579 (8)
C10	0.2305 (4)	0.2831 (4)	0.1550 (2)	0.0671 (9)
C11	0.2781 (4)	0.1768 (3)	0.0886 (2)	0.0658 (8)
C12	0.4556 (4)	0.2291 (3)	0.0586 (1)	0.0558 (7)
C13	0.5910 (3)	0.3871 (3)	0.0953 (1)	0.0439 (6)
C14	0.7746 (3)	0.4365 (3)	0.0564 (1)	0.0455 (7)
C15	0.5568 (5)	0.7174 (4)	0.6042 (2)	0.083 (1)
C16	0.4722 (4)	0.8523 (4)	0.5777 (2)	0.079 (1)
C17	0.5414 (4)	0.9248 (3)	0.5146 (1)	0.0539 (7)
C18	0.6927 (5)	0.8521 (4)	0.4809 (2)	0.083 (1)
C19	0.7694 (5)	0.7169 (4)	0.5118 (2)	0.086 (1)
H1	1.177 (5)	0.499 (4)	0.388 (2)	0.13 (1)
H2	0.973 (6)	0.369 (4)	−0.038 (2)	0.16 (1)
H3	1.1026	0.8829	0.3459	0.0669
H4	0.9764	1.1171	0.3005	0.0780
H5	0.6544	1.0721	0.2011	0.0795
H6	0.4678	0.7955	0.1438	0.0679
H7	0.3253	0.5124	0.2379	0.0695
H8	0.1065	0.2486	0.1755	0.0806
H9	0.1890	0.0682	0.0637	0.0789
H10	0.4872	0.1564	0.0118	0.0669
H11	0.5043	0.6699	0.6479	0.1002
H12	0.3655	0.8955	0.6032	0.0953
H13	0.7454	0.8947	0.4361	0.0995
H14	0.8749	0.6697	0.4872	0.1037

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.072 (1)	0.058 (1)	0.071 (1)	0.0196 (9)	−0.0139 (9)	0.0136 (9)
O2	0.092 (1)	0.041 (1)	0.115 (2)	0.0108 (10)	−0.028 (1)	0.020 (1)
O3	0.064 (1)	0.066 (1)	0.063 (1)	0.0035 (9)	0.0230 (9)	−0.0095 (9)
O4	0.070 (1)	0.052 (1)	0.070 (1)	−0.0044 (9)	0.0312 (9)	−0.0003 (9)
N1	0.074 (2)	0.074 (2)	0.067 (1)	0.028 (1)	0.001 (1)	0.021 (1)
C1	0.056 (1)	0.043 (1)	0.050 (1)	0.017 (1)	0.009 (1)	0.010 (1)
C2	0.051 (1)	0.040 (1)	0.040 (1)	0.012 (1)	0.013 (1)	0.0083 (10)
C3	0.064 (2)	0.045 (1)	0.054 (1)	0.008 (1)	0.006 (1)	0.009 (1)
C4	0.088 (2)	0.039 (1)	0.064 (2)	0.006 (1)	0.010 (1)	0.008 (1)
C5	0.093 (2)	0.043 (1)	0.068 (2)	0.023 (1)	0.012 (2)	0.020 (1)
C6	0.067 (2)	0.052 (1)	0.052 (1)	0.022 (1)	0.005 (1)	0.014 (1)
C7	0.050 (1)	0.041 (1)	0.041 (1)	0.012 (1)	0.014 (1)	0.0094 (10)
C8	0.046 (1)	0.047 (1)	0.045 (1)	0.013 (1)	0.008 (1)	0.018 (1)
C9	0.054 (2)	0.066 (2)	0.057 (1)	0.012 (1)	0.018 (1)	0.016 (1)
C10	0.053 (2)	0.077 (2)	0.073 (2)	0.000 (1)	0.014 (1)	0.030 (2)
C11	0.059 (2)	0.059 (2)	0.070 (2)	−0.007 (1)	0.002 (1)	0.016 (1)
C12	0.057 (2)	0.049 (1)	0.056 (1)	0.005 (1)	0.005 (1)	0.008 (1)
C13	0.044 (1)	0.044 (1)	0.042 (1)	0.010 (1)	0.004 (1)	0.0094 (10)
C14	0.047 (1)	0.045 (1)	0.041 (1)	0.010 (1)	0.004 (1)	0.005 (1)
C15	0.088 (2)	0.107 (2)	0.074 (2)	0.037 (2)	0.020 (2)	0.050 (2)
C16	0.075 (2)	0.105 (2)	0.081 (2)	0.044 (2)	0.029 (2)	0.047 (2)
C17	0.053 (1)	0.064 (2)	0.044 (1)	0.015 (1)	0.002 (1)	0.013 (1)
C18	0.110 (2)	0.093 (2)	0.074 (2)	0.054 (2)	0.044 (2)	0.036 (2)
C19	0.106 (2)	0.089 (2)	0.084 (2)	0.051 (2)	0.035 (2)	0.025 (2)

Geometric parameters (Å, º)

O1—C1	1.321 (3)	C8—C9	1.389 (3)
O1—H1	1.04 (3)	C8—C13	1.408 (3)
O2—C1	1.197 (3)	C9—C10	1.383 (3)
O3—C14	1.272 (2)	C9—H7	0.95
O3—H2	1.33 (4)	C10—C11	1.370 (4)
O4—C14	1.256 (2)	C10—H8	0.95
N1—C15	1.309 (3)	C11—C12	1.372 (3)
N1—C19	1.313 (3)	C11—H9	0.95
C1—C2	1.489 (3)	C12—C13	1.399 (3)
C2—C3	1.388 (3)	C12—H10	0.95
C2—C7	1.402 (3)	C13—C14	1.486 (3)
C3—C4	1.379 (3)	C15—C16	1.375 (4)
C3—H3	0.95	C15—H11	0.95
C4—C5	1.372 (3)	C16—C17	1.370 (3)
C4—H4	0.95	C16—H12	0.95
C5—C6	1.375 (3)	C17—C17^i	1.497 (4)
C5—H5	0.95	C17—C18	1.368 (3)
C6—C7	1.393 (3)	C18—C19	1.382 (4)
C6—H6	0.95	C18—H13	0.95
C7—C8	1.498 (3)	C19—H14	0.95
C1—O1—H1	111 (1)	C9—C10—C11	120.5 (2)
C14—O3—H2	117 (1)	C9—C10—H8	119.7
C15—N1—C19	115.8 (2)	C11—C10—H8	119.8
O1—C1—O2	121.9 (2)	C10—C11—C12	119.3 (2)
O1—C1—C2	113.2 (2)	C10—C11—H9	120.4
O2—C1—C2	124.9 (2)	C12—C11—H9	120.4
C1—C2—C3	119.0 (2)	C11—C12—C13	121.3 (2)
C1—C2—C7	121.5 (2)	C11—C12—H10	119.3
C3—C2—C7	119.4 (2)	C13—C12—H10	119.3
C2—C3—C4	121.4 (2)	C8—C13—C12	119.6 (2)
C2—C3—H3	119.3	C8—C13—C14	122.7 (2)
C4—C3—H3	119.3	C12—C13—C14	117.7 (2)
C3—C4—C5	119.2 (2)	O3—C14—O4	122.2 (2)
C3—C4—H4	120.4	O3—C14—C13	117.5 (2)
C5—C4—H4	120.4	O4—C14—C13	120.2 (2)
C4—C5—C6	120.2 (2)	N1—C15—C16	124.3 (3)
C4—C5—H5	119.9	N1—C15—H11	117.8
C6—C5—H5	119.9	C16—C15—H11	117.8
C5—C6—C7	121.6 (2)	C15—C16—C17	120.2 (3)
C5—C6—H6	119.2	C15—C16—H12	119.9
C7—C6—H6	119.2	C17—C16—H12	119.9
C2—C7—C6	118.0 (2)	C16—C17—C17^i	122.1 (3)
C2—C7—C8	124.6 (2)	C16—C17—C18	115.6 (2)
C6—C7—C8	117.4 (2)	C17^i—C17—C18	122.3 (3)
C7—C8—C9	117.8 (2)	C17—C18—C19	120.3 (2)
C7—C8—C13	124.4 (2)	C17—C18—H13	119.8
C9—C8—C13	117.7 (2)	C19—C18—H13	119.8
C8—C9—C10	121.6 (2)	N1—C19—C18	123.8 (3)
C8—C9—H7	119.2	N1—C19—H14	118.1
C10—C9—H7	119.2	C18—C19—H14	118.1

Symmetry code: (i) −x+1, −y+2, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H2···O4^ii	1.33 (4)	1.29 (4)	2.618 (3)	171 (3)
O1—H1···N1^iii	1.04 (3)	1.65 (3)	2.691 (4)	172 (3)
C4—H4···O2^iv	0.95	2.56	3.235 (4)	128
C6—H6···O3^v	0.95	2.57	3.472 (4)	158
C3—H3···O1	0.95	2.33	2.683 (4)	101
C12—H10···O3	0.95	2.39	2.730 (4)	100

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