The cocrystal of 3-hydroxy-2-naphthoic acid and 4,4′-bipyridine

4,4′-Bipyridine cocrystallizes with 3-hydroxy-2-naphthoic acid in a 1:2 ratio to give a centrosymmetric three-component supra­molecular adduct, namely 3-hydroxy-2-naphthoic acid–4,4′-bipyridine (2/1), C₁₁H₈O₃·0.5C₁₀H₈N₂, in which 4,4′-bipyridine is located on an inversion center. The pyridine–carboxylic acid heterosynthon generates an infinite one-dimensional hydrogen-bonded chain via π–π inter­actions between naphthyl and 4,4′-bipyridine groups. The one-dimensional chains are further assembled into a three-dimensional network by weak C—H...π inter­actions between pyridyl and naphthyl rings, and C—H...O inter­actions between 3-hydroxy-2-naphthoic acid mol­ecules.

S1. Comment

Crystal engineering of organic molecules has been exploited in organic materials and even in active pharmaceutical ingredients (Desiraju, 2003; Almarsson & Zaworotko, 2004). Supramolecular synthons provide an effective strategy for synthesizing the specific organic supramolecular solids (Desiraju,1997). In particular, supramolecular heterosynthons have great advantages in designing the cocrystals of two or more components. For example, Bailey Walsh et al. (2003) inserted 4,4'-bipyridine between carboxylic acid moieties and utilized the pyridine–carboxylic acid heterosynthon to obtain several pharmaceutical cocrystals. Weak C—H···O interaction plays an important role in the heterosynthon. The pyridyl ring of 4,4'-bipyridine is also able to provide other weak interactions, such as π–π and C—H···π interactions. We have treated 4,4'-bipyridine with 3-hydroxy-2-naphthoic acid and obtained the crystalline supramolecular adduct (I), in which the pyridine–carboxylic acid heterosynthon generates a molecular complex which is engineered into a three-dimensional assembly by π–π and C—H···π interactions between pyridyl and naphthoic rings.

X-ray diffraction shows that the centrosymmetric three-component adduct is formed between 3-hydroxy-2-naphthoic acid and 4,4'-bipyridine in 2:1 ratio. The expected pyridine–carboxylic acid heterosynthon contains hydrogen-bonding [N1···O1 = 2.625 (2) A°] and C—H···O interaction (2.375 A°, 130.18°) between pyridyl ring and carboxylic acid group. The hydroxy group is involved in intramolecular hydrogen-bonding [O3···O2 = 2.557 (2) A°] with the carbonyl O atom (Table 2). The 4,4'-bipyridine molcule is located in the center of the adduct and on the inversion center, and the two pyridine rings are coplanar. Moreover, the naphthoic acid rings are parallel to the 4,4'-bipyridine molecule. The crystal packing of the adduct is controlled by two distinct weak interactions between the 4,4'-bipyridine and naphthoic acid rings. One naphthoic acid ring is involved in π–π interactions with a pyridyl ring at (x + 1, y, z) at a centroid–centroid distance of 3.630 Å (Table 3). Two adduct molecules connected together are parallel displaced and along a axis the adduct is linked into a one-dimensional infinite chain by face-to-face π stacking (Fig. 2). There also exists a point-to-face C15—H15···π interaction (H···centroid = 2.858 Å and C15—H15···π= 158°) between the CH group of a pyridyl ring and an adjacent naphthoic acid ring (−x, y − 1/2, 1/2 − z). Moreover, the hydroxy O atom is involved in C9—H9···O3 interactions (2.696 Å and 125.81°) with naphthoic acid rings related by (1 − x, y − 1/2, 1/2 − z). For the whole adduct molecule, the naphthoic acid rings lie in the end and pyridyl rings lie in the middle. Thus, each adduct molecule interacts with eight adjacent molecules in four directions, and each one-dimensional chain resulting from π–π interactions connects four chains through weak C—H ···π and C—H···O interactions into a three-dimensional assembly (Fig. 3), which exhibits intense photoluminescence at 534 nm upon photo-excitation at 365 nm. 3-Hydroxy-2-naphthoic acid exhibits luminescence at 524 nm upon excitation at 365 nm, which shows that the interactions between 3-hydroxy-2-naphthoic acid and 4,4'- bipyridine slightly affect the luminescent property. In conclusion, in the cocrystal 3-hydroxy-2-naphthoic acid interacts with 4,4'-bipyridine in four ways: O—H···N hydrogen-bonding, weak C—H···O, π–π stacking and C—H···π interactions. The four non-covalent interactions together with the C—H···O interactions between naphthoic acid molecules result in a three-dimensional supramolecular assembly. This result also demonstrates the fact that the pyridyl ring is an excellent cocrystal former.

S2. Experimental

A mixture of 3-hydroxy-2-naphthoic acid (0.075 g, 0.4 mmol) and 4,4'-bipyridine (0.032 g, 0.2 mmol) was stirred in enthanol (10 ml). The solution was kept in air and after several days yellow crystals were obtained with 70% yield.

S3. Refinement

All H atoms were constrained to ride on their parent atoms with U_iso(H) values of 1.2U_eq(parent atom) (C—H = 0.95 Å).

Computing details

Data collection: CrystalClear (Rigaku Corporation, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. A plot of adduct (I) with 30% probability displacement ellipsoids. The dashed lines indicate hydrogen bonds.
	Fig. 2. The one-dimensional structure of (I) along axis. The dashed lines indicate hydrogen bonds or π–π interactions
	Fig. 3. The three-dimensional structure of (I), viewed along the a axis. The dotted lines indicate C—H···O(π) interactions

3-hydroxy-2-naphthoic–4,4'-bipyridine (2/1)

Crystal data

C11H8O3·0.5C10H8N2	F(000) = 556
Mr = 266.27	Dx = 1.367 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.999 (5) Å	Cell parameters from 2304 reflections
b = 11.735 (7) Å	θ = 2.9–27.4°
c = 12.393 (7) Å	µ = 0.10 mm^−1
β = 98.799 (12)°	T = 293 K
V = 1293.4 (13) Å^3	Prism, yellow
Z = 4	0.44 × 0.38 × 0.10 mm

Data collection

Make and Model?? CCD diffractometer	2934 independent reflections
Radiation source: fine-focus sealed tube	1768 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
Detector resolution: 28.5714 pixels mm^-1	θmax = 27.4°, θmin = 2.3°
CCD_Profile_fitting scans	h = −11→11
Absorption correction: multi-scan ?	k = −13→15
Tmin = 0.821, Tmax = 1.000	l = −15→15
9720 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.054	H-atom parameters constrained
wR(F^2) = 0.158	w = 1/[σ^2(Fo^2) + (0.0944P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.96	(Δ/σ)max < 0.001
2934 reflections	Δρmax = 0.27 e Å^−3
182 parameters	Δρmin = −0.19 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.29 (2)

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.15570 (12)	0.05389 (12)	0.22487 (10)	0.0717 (4)
H1	0.0643	0.0462	0.1993	0.086*
O2	0.13676 (15)	0.19441 (15)	0.10344 (14)	0.0983 (5)
O3	0.37149 (18)	0.30019 (14)	0.06488 (12)	0.0971 (5)
H3	0.2812	0.2792	0.0545	0.117*
N1	−0.12165 (14)	0.01352 (13)	0.13242 (11)	0.0588 (4)
C1	0.21090 (19)	0.13774 (17)	0.17723 (15)	0.0633 (5)
C2	0.37275 (17)	0.16406 (15)	0.21240 (14)	0.0552 (4)
C3	0.4462 (2)	0.24535 (16)	0.15306 (15)	0.0650 (5)
C4	0.5967 (2)	0.26847 (18)	0.18401 (17)	0.0754 (6)
H4	0.6446	0.3225	0.1438	0.091*
C5	0.68033 (19)	0.21370 (17)	0.27386 (16)	0.0685 (5)
C6	0.8378 (2)	0.2340 (2)	0.3060 (2)	0.0927 (8)
H6	0.8886	0.2862	0.2657	0.111*
C7	0.9147 (2)	0.1795 (3)	0.3930 (3)	0.1102 (10)
H7	1.0195	0.1931	0.4122	0.132*
C8	0.8438 (3)	0.1035 (3)	0.4555 (2)	0.1070 (9)
H8	0.8992	0.0681	0.5180	0.128*
C9	0.6928 (2)	0.0803 (2)	0.42592 (19)	0.0876 (7)
H9	0.6451	0.0273	0.4675	0.105*
C10	0.60855 (18)	0.13392 (17)	0.33503 (15)	0.0646 (5)
C11	0.45347 (18)	0.11116 (16)	0.30113 (14)	0.0598 (5)
H11	0.4042	0.0577	0.3411	0.072*
C12	−0.16956 (19)	0.07572 (18)	0.04482 (17)	0.0737 (6)
H12	−0.1002	0.1252	0.0178	0.088*
C13	−0.31515 (18)	0.07213 (17)	−0.00897 (16)	0.0692 (6)
H13	−0.3436	0.1184	−0.0716	0.083*
C14	−0.22045 (19)	−0.05580 (17)	0.16810 (16)	0.0684 (5)
H14	−0.1881	−0.1016	0.2305	0.082*
C15	−0.36796 (18)	−0.06393 (16)	0.11825 (15)	0.0651 (5)
H15	−0.4344	−0.1150	0.1464	0.078*
C16	−0.41996 (15)	0.00183 (13)	0.02734 (12)	0.0482 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0449 (6)	0.0862 (10)	0.0820 (9)	−0.0066 (6)	0.0032 (6)	0.0061 (7)
O2	0.0602 (8)	0.1003 (12)	0.1237 (12)	−0.0072 (7)	−0.0199 (8)	0.0347 (9)
O3	0.0899 (10)	0.0976 (12)	0.0998 (11)	−0.0135 (9)	0.0014 (8)	0.0287 (9)
N1	0.0444 (7)	0.0642 (10)	0.0676 (9)	−0.0032 (6)	0.0076 (6)	−0.0012 (7)
C1	0.0491 (9)	0.0667 (12)	0.0718 (11)	0.0013 (8)	0.0014 (8)	−0.0057 (9)
C2	0.0463 (8)	0.0570 (10)	0.0619 (10)	−0.0009 (7)	0.0075 (8)	−0.0119 (8)
C3	0.0635 (10)	0.0634 (12)	0.0676 (11)	−0.0022 (9)	0.0079 (9)	−0.0051 (9)
C4	0.0646 (11)	0.0727 (13)	0.0929 (14)	−0.0166 (10)	0.0246 (11)	−0.0134 (11)
C5	0.0488 (9)	0.0717 (12)	0.0854 (13)	−0.0056 (8)	0.0114 (9)	−0.0300 (10)
C6	0.0530 (11)	0.1053 (19)	0.1207 (18)	−0.0148 (11)	0.0157 (12)	−0.0519 (15)
C7	0.0480 (11)	0.141 (3)	0.135 (2)	0.0041 (14)	−0.0056 (14)	−0.072 (2)
C8	0.0687 (14)	0.133 (2)	0.1091 (19)	0.0320 (15)	−0.0187 (14)	−0.0380 (17)
C9	0.0679 (12)	0.1027 (18)	0.0863 (15)	0.0162 (11)	−0.0076 (11)	−0.0147 (12)
C10	0.0494 (9)	0.0725 (13)	0.0699 (11)	0.0058 (8)	0.0022 (8)	−0.0215 (9)
C11	0.0479 (8)	0.0653 (11)	0.0658 (11)	−0.0008 (8)	0.0074 (8)	−0.0056 (8)
C12	0.0465 (9)	0.0862 (14)	0.0858 (14)	−0.0163 (9)	0.0021 (9)	0.0195 (11)
C13	0.0504 (9)	0.0788 (14)	0.0761 (12)	−0.0127 (8)	0.0023 (8)	0.0242 (9)
C14	0.0519 (9)	0.0785 (13)	0.0722 (12)	−0.0030 (9)	0.0010 (8)	0.0154 (9)
C15	0.0484 (8)	0.0729 (12)	0.0738 (12)	−0.0094 (8)	0.0083 (8)	0.0166 (9)
C16	0.0414 (7)	0.0500 (9)	0.0540 (9)	−0.0021 (6)	0.0103 (6)	−0.0049 (7)

Geometric parameters (Å, º)

O1—C1	1.286 (2)	C7—C8	1.398 (4)
O1—H1	0.8400	C7—H7	0.9500
O2—C1	1.240 (2)	C8—C9	1.379 (3)
O3—C3	1.355 (2)	C8—H8	0.9500
O3—H3	0.8400	C9—C10	1.407 (3)
N1—C12	1.324 (2)	C9—H9	0.9500
N1—C14	1.330 (2)	C10—C11	1.420 (2)
C1—C2	1.487 (2)	C11—H11	0.9500
C2—C11	1.370 (2)	C12—C13	1.377 (3)
C2—C3	1.427 (3)	C12—H12	0.9500
C3—C4	1.377 (3)	C13—C16	1.379 (2)
C4—C5	1.401 (3)	C13—H13	0.9500
C4—H4	0.9500	C14—C15	1.379 (2)
C5—C10	1.421 (3)	C14—H14	0.9500
C5—C6	1.432 (3)	C15—C16	1.387 (2)
C6—C7	1.350 (4)	C15—H15	0.9500
C6—H6	0.9500	C16—C16^i	1.496 (3)
C1—O1—H1	109.5	C7—C8—H8	120.2
C3—O3—H3	109.5	C8—C9—C10	120.8 (3)
C12—N1—C14	117.34 (14)	C8—C9—H9	119.6
O2—C1—O1	123.16 (16)	C10—C9—H9	119.6
O2—C1—C2	119.81 (17)	C9—C10—C11	122.5 (2)
O1—C1—C2	117.01 (16)	C9—C10—C5	119.28 (18)
C11—C2—C3	119.08 (15)	C11—C10—C5	118.21 (18)
C11—C2—C1	121.08 (16)	C2—C11—C10	121.91 (18)
C3—C2—C1	119.84 (16)	C2—C11—H11	119.0
O3—C3—C4	118.45 (18)	C10—C11—H11	119.0
O3—C3—C2	121.45 (16)	N1—C12—C13	123.12 (16)
C4—C3—C2	120.09 (18)	N1—C12—H12	118.4
C3—C4—C5	121.13 (19)	C13—C12—H12	118.4
C3—C4—H4	119.4	C12—C13—C16	120.53 (17)
C5—C4—H4	119.4	C12—C13—H13	119.7
C4—C5—C10	119.57 (16)	C16—C13—H13	119.7
C4—C5—C6	122.2 (2)	N1—C14—C15	122.69 (17)
C10—C5—C6	118.2 (2)	N1—C14—H14	118.7
C7—C6—C5	120.5 (2)	C15—C14—H14	118.7
C7—C6—H6	119.7	C14—C15—C16	120.51 (15)
C5—C6—H6	119.7	C14—C15—H15	119.7
C6—C7—C8	121.5 (2)	C16—C15—H15	119.7
C6—C7—H7	119.2	C13—C16—C15	115.80 (14)
C8—C7—H7	119.2	C13—C16—C16^i	121.91 (18)
C9—C8—C7	119.6 (3)	C15—C16—C16^i	122.29 (17)
C9—C8—H8	120.2

Symmetry code: (i) −x−1, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1	0.84	1.79	2.625 (2)	172
O3—H3···O2	0.84	1.81	2.557 (2)	147