N-(8-Quinolyl)­pyridine-2-carbox­amide

The title compound, C₁₅H₁₁N₃O, is basically planar except that the pyridine ring is slightly titled, the dihedral angle between the pyridyl and quinolyl rings being 3.55 (5)°. The crystal grows in two directions and the crystal packing is stabilized by π–π stacking interactions.

S1. Comment

Quinoxaline derivatives, such as XK469, showed unusual solid-tumor selectivity and activity against multidrug-resistant cancer cells (Gao et al., 1999). Some platinum complexes of pyridine and quinoline ligands, such as trans-dichlorodipyridineplatinum(II) and trans-amminedichloroquinolineplatinum(II), show comparable anticancer activity to cisplatin in cisplatin-sensitive and -resistant cell lines (Wong & Giandomenico, 1999). Moreover, some metallointercalators have been widely used in DNA structural and mechanistic studies (Erkkila et al., 1999). The aminoquinoline-based ligands possess strong fluorescent property which could be used as a probe for DNA binding (Fahrni and O'halloran, 1999; Nasir et al., 1999). Therefore, we synthesized the title compound, (I), in order to investigate their binding ability towards metal ions and DNA. This ligand contains pyridine, amide and quinoline nitrogen atoms which are able to coordinate to metal ions, such as Zn^II and Cu^II (Fahrni and O'halloran, 1999; Nasir et al., 1999; Amendola et al., 1999). Studies of the metal complexes of the ligand will be reported elsewhere. \scheme

The X-ray crystallographic study shows that both lengths and angles are within the normal ranges. The N2—C6 and N2—C7 bond distances in (I) are comparable to those in [N,N'-bis(2-pyridinecarboxamido)-1,2-benzene]copper(II) [1.337 (3) and 1.404 (2) Å; Chapman et al., 1980] and N,N'-(4,5-dichloro-o-phenylene)bis(4-tert-butylpyridine-2-carboxamide) [1.350 (4) and 1.401 (4) Å; Fun et al., 1999), while the C—C and C═O bond lengths are similar to those reported in [N,N'-bis(2-pyridinecarboxamide)-1,2-benzene]nickel(II) monohydrate (Stephens & Vagg, 1986). The molecule of (I) is almost planar, except that the pyridyl ring is slightly tilted, the dihedral angle between pyridyl and quinolyl rings being 3.55 (5)°. There are four intramolecular hydrogen bonds in the crystal (see Table 2) which could be the driving force to have N1 and N3 in the same side of the molecule.

The crystal is a thin plate and grows in two different directions which cross each other and the angle between these two orientations is 60.8°. There is a π–π stacking interaction between the adjacent molecules packed in the same direction. The distance between the two adjacent parallel aromatic rings [C1–C5/N1 and C7ⁱ–C11ⁱ/C15ⁱ; symmetry code: (i) 1 - x, 2 - y,-z] is 3.68 (2) Å, and the shortest distance is C2···C9ⁱ of 3.481 (4) Å. This kind of interaction belongs to the face-to-face type, with a little offset, and the molecules are arranged in a head-to-tail fashion, i.e. the pyridyl group faces the quinoline group.

In order to understand the electron-donating ability of the three N atoms, ab initio calculations (method HF/3–21g*) in GAUSSIAN98 (Frisch et al., 1998) were carried out. This gave rise to electron-distribution values of -0.731 e, -1.095 e and -0.746 e for N1, N2 and N3, respectively.

S2. Experimental

The title compound was obtained by the reaction of one molar equivalent of pyridine-2-carboxylic acid and 8-aminoquinoline in the presence of one molar equivalent of triphenyl phosphite in pyridine at 473 K for 4 h (Leung et al., 1991). Single crystals suitable for X-ray diffraction were recrystallized from pyridine and ethanol.

S3. Refinement

All H atoms were placed in geometrically calculated positions (C—H = 0.93 Å and N—H = 0.86 Å), with U_iso = 1.2U_eq(parent atom).

Computing details

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: SHELXTL(Sheldrick, 1997); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The structure of the title compound showing 50% probability displacement ellipsoids and the atom-numbering scheme.

N-(8-quinolyl)-2-pyridinecarboxamide

Crystal data

C15H11N3O	F(000) = 520
Mr = 249.27	Dx = 1.354 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.677 (2) Å	Cell parameters from 41 reflections
b = 7.915 (3) Å	θ = 5.2–15.1°
c = 20.408 (5) Å	µ = 0.09 mm^−1
β = 99.64 (2)°	T = 293 K
V = 1222.5 (6) Å^3	Thick plate, colorless
Z = 4	0.50 × 0.50 × 0.40 mm

Data collection

Siemens P4 diffractometer	1406 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.026
Graphite monochromator	θmax = 25.0°, θmin = 2.0°
2θ/ω scans	h = −1→9
Absorption correction: empirical (using intensity measurements) (North et al., 1968)	k = −1→9
Tmin = 0.956, Tmax = 0.965	l = −24→24
3082 measured reflections	3 standard reflections every 97 reflections
2149 independent reflections	intensity decay: 7.1%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.122	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0531P)^2 + 0.0469P] where P = (Fo^2 + 2Fc^2)/3
2149 reflections	(Δ/σ)max < 0.001
172 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.16 e Å^−3

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	0.20798 (18)	0.7992 (2)	−0.01580 (7)	0.0709 (5)
N1	0.6691 (2)	0.7271 (2)	0.01886 (8)	0.0547 (5)
N2	0.4150 (2)	0.8663 (2)	0.07432 (7)	0.0496 (4)
H2B	0.5261	0.8576	0.0893	0.060*
N3	0.5875 (2)	0.9591 (2)	0.19282 (8)	0.0569 (5)
C1	0.7989 (3)	0.6621 (3)	−0.00868 (11)	0.0645 (6)
H1A	0.9124	0.6632	0.0159	0.077*
C2	0.7751 (3)	0.5928 (3)	−0.07184 (12)	0.0698 (7)
H2A	0.8701	0.5485	−0.0891	0.084*
C3	0.6099 (3)	0.5910 (3)	−0.10802 (11)	0.0676 (6)
H3A	0.5898	0.5450	−0.1506	0.081*
C4	0.4720 (3)	0.6580 (3)	−0.08092 (10)	0.0590 (6)
H4A	0.3576	0.6583	−0.1048	0.071*
C5	0.5076 (2)	0.7247 (2)	−0.01761 (9)	0.0461 (5)
C6	0.3611 (3)	0.7997 (3)	0.01303 (9)	0.0494 (5)
C7	0.3154 (2)	0.9474 (2)	0.11667 (9)	0.0467 (5)
C8	0.1381 (2)	0.9819 (3)	0.10156 (10)	0.0549 (5)
H8A	0.0746	0.9491	0.0607	0.066*
C9	0.0517 (3)	1.0666 (3)	0.14763 (11)	0.0641 (6)
H9A	−0.0689	1.0878	0.1368	0.077*
C10	0.1402 (3)	1.1180 (3)	0.20734 (11)	0.0620 (6)
H10A	0.0807	1.1744	0.2369	0.074*
C11	0.3241 (3)	1.0855 (3)	0.22468 (10)	0.0531 (5)
C12	0.4277 (3)	1.1372 (3)	0.28501 (11)	0.0667 (6)
H12A	0.3759	1.1966	0.3161	0.080*
C13	0.6033 (3)	1.1003 (3)	0.29791 (11)	0.0736 (7)
H13A	0.6729	1.1344	0.3374	0.088*
C14	0.6763 (3)	1.0095 (3)	0.25017 (10)	0.0706 (7)
H14A	0.7959	0.9831	0.2597	0.085*
C15	0.4114 (2)	0.9977 (3)	0.17963 (9)	0.0469 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0489 (9)	0.0973 (13)	0.0616 (9)	0.0062 (9)	−0.0048 (7)	−0.0098 (9)
N1	0.0447 (10)	0.0606 (12)	0.0595 (10)	0.0006 (9)	0.0103 (8)	−0.0011 (8)
N2	0.0430 (9)	0.0589 (11)	0.0458 (9)	0.0045 (8)	0.0045 (7)	−0.0022 (8)
N3	0.0490 (10)	0.0721 (13)	0.0493 (10)	−0.0010 (9)	0.0072 (8)	−0.0012 (9)
C1	0.0493 (12)	0.0711 (16)	0.0744 (15)	0.0034 (12)	0.0143 (11)	−0.0004 (13)
C2	0.0755 (16)	0.0657 (16)	0.0746 (15)	0.0099 (13)	0.0311 (13)	0.0005 (13)
C3	0.0886 (17)	0.0640 (15)	0.0517 (13)	0.0073 (14)	0.0156 (12)	−0.0019 (11)
C4	0.0655 (13)	0.0598 (14)	0.0503 (12)	0.0040 (12)	0.0055 (10)	−0.0007 (11)
C5	0.0513 (11)	0.0434 (11)	0.0440 (10)	−0.0032 (10)	0.0090 (9)	0.0059 (9)
C6	0.0492 (12)	0.0507 (12)	0.0468 (11)	0.0000 (10)	0.0035 (9)	0.0063 (10)
C7	0.0486 (11)	0.0446 (12)	0.0476 (10)	0.0044 (10)	0.0104 (9)	0.0075 (9)
C8	0.0496 (12)	0.0630 (14)	0.0511 (11)	0.0070 (11)	0.0057 (9)	0.0081 (11)
C9	0.0545 (12)	0.0733 (16)	0.0666 (14)	0.0174 (12)	0.0165 (11)	0.0138 (12)
C10	0.0637 (14)	0.0599 (15)	0.0672 (14)	0.0148 (12)	0.0254 (12)	0.0064 (11)
C11	0.0656 (13)	0.0463 (12)	0.0504 (11)	0.0001 (11)	0.0184 (10)	0.0043 (10)
C12	0.0842 (17)	0.0598 (15)	0.0592 (13)	−0.0058 (13)	0.0210 (12)	−0.0062 (11)
C13	0.0789 (17)	0.0851 (19)	0.0557 (13)	−0.0134 (15)	0.0081 (12)	−0.0121 (13)
C14	0.0583 (13)	0.0947 (19)	0.0567 (13)	−0.0092 (14)	0.0039 (11)	−0.0083 (13)
C15	0.0479 (11)	0.0467 (12)	0.0478 (11)	−0.0001 (10)	0.0122 (9)	0.0063 (9)

Geometric parameters (Å, º)

O1—C6	1.223 (2)	C5—C6	1.498 (3)
N1—C1	1.327 (3)	C7—C8	1.372 (3)
N1—C5	1.335 (2)	C7—C15	1.427 (3)
N2—C6	1.357 (2)	C8—C9	1.408 (3)
N2—C7	1.401 (2)	C9—C10	1.355 (3)
N3—C14	1.314 (2)	C10—C11	1.420 (3)
N3—C15	1.368 (2)	C11—C12	1.410 (3)
C1—C2	1.384 (3)	C11—C15	1.408 (3)
C2—C3	1.357 (3)	C12—C13	1.361 (3)
C3—C4	1.380 (3)	C13—C14	1.401 (3)
C4—C5	1.380 (3)
C1—N1—C5	116.9 (2)	C8—C7—C15	119.4 (2)
C6—N2—C7	129.3 (2)	N2—C7—C15	115.5 (2)
C14—N3—C15	117.1 (2)	C7—C8—C9	120.4 (2)
N1—C1—C2	123.8 (2)	C10—C9—C8	121.5 (2)
C3—C2—C1	118.5 (2)	C9—C10—C11	119.9 (2)
C2—C3—C4	119.2 (2)	C12—C11—C15	116.9 (2)
C5—C4—C3	118.5 (2)	C12—C11—C10	123.8 (2)
N1—C5—C4	123.2 (2)	C15—C11—C10	119.2 (2)
N1—C5—C6	117.0 (2)	C13—C12—C11	120.1 (2)
C4—C5—C6	119.8 (2)	C12—C13—C14	118.3 (2)
O1—C6—N2	124.4 (2)	N3—C14—C13	124.5 (2)
O1—C6—C5	121.7 (2)	N3—C15—C11	123.0 (2)
N2—C6—C5	113.9 (2)	N3—C15—C7	117.3 (2)
C8—C7—N2	125.1 (2)	C11—C15—C7	119.7 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2B···N1	0.86	2.21	2.653 (2)	112
N2—H2B···N3	0.86	2.24	2.659 (2)	110
C4—H4A···O1	0.93	2.56	2.833 (3)	97
C8—H8A···O1	0.93	2.33	2.923 (3)	121