organic compounds
(2E)-1-(2,4-Dimethylquinolin-3-yl)-3-(thiophen-2-yl)prop-2-en-1-one†
aDepartment of Chemistry, BITS, Pilani – K. K. Birla Goa Campus, Goa 403 726, India, bDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia, and cChemistry Department, Faculty of Science, King Abdulaziz University, PO Box 80203 Jeddah, Saudi Arabia
*Correspondence e-mail: edward.tiekink@gmail.com
Two independent but virtually identical molecules comprise the 18H15NOS. With reference to the quinolin-3-yl group, the 3-(thiophen-2-yl)prop-2-en-1-one residue is almost perpendicular, with all but the carbonyl O atom lying to one side of the plane. This conformation is reflected by the C—C—C—C torsion angles of −102.2 (3) and 81.1 (3)° in the two independent molecules. The dihedral angle formed between the 13 non-H atoms directly associated with the quinolin-3-yl group and the thiophen-2-yl ring is 87.70 (11)° [83.85 (10)° for the second independent molecule]. The presence of C—H⋯O, C—H⋯N and π–π interactions [centroid–centroid distance = 3.5590 (12) Å] lead to supramolecular chains along the c-axis direction. These are connected along the a-axis direction by C—H⋯π interactions. The resultant supramolecular layers stack along the b axis.
in the title compound, CRelated literature
For background details and biological applications of quinolines, see: Kalluraya & Sreenivasa (1998); Xiang et al. (2006). For the biological activity of see: Dimmock et al. (1999); Siddiqui et al. (2008).
Experimental
Crystal data
|
Refinement
|
Data collection: CrysAlis PRO (Agilent, 2010); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997), DIAMOND (Brandenburg, 2006) and Qmol (Gans & Shalloway, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
10.1107/S1600536811031485/hg5075sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811031485/hg5075Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536811031485/hg5075Isup3.cml
A mixture of 3-acetyl-2,4-dimethylquinoline (0.01 M), 2-thiophenecarboxaldehyde (0.01 M) and a catalytic amount of KOH in distilled ethanol was stirred for 12 h at room temperature. The resulting mixture was neutralized with dilute acetic acid. The solid that formed was filtered, dried and purified by
using 1:3 mixture of ethyl acetate and hexane. Recrystallization was by slow evaporation of its acetone solution which yielded colourless needles. M.pt. 418–420 K. Yield: 82%.Carbon-bound H-atoms were placed in calculated positions [C—H 0.95 to 0.98 Å, Uiso(H) 1.2 to 1.5Ueq(C)] and were included in the
in the riding model approximation. Each thiophen-2-yl ring was found to be disordered so that there were two co-planar but oppositely orientated orientations for each. Pairs of 1,2- and 1,3-related distances involving the unprimed and primed atoms were restrained to within 0.01 Å of each other. Each ring was restrained to lie on a plane within 0.01 Å. The anisotropic displacement factors of the primed atoms were set to those of the unprimed ones, and were restrained to be nearly isotropic. From the the major component of the S1- and S2-containing rings were 0.765 (2) and 0.814 (2), respectively.Data collection: CrysAlis PRO (Agilent, 2010); cell
CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997), DIAMOND (Brandenburg, 2006) and Qmol (Gans & Shalloway, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).Fig. 1. The molecular structures of the two independent molecules comprising the asymmetric unit of (I) showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level. | |
Fig. 2. Overlay diagram of the two independent molecules comprising the asymmetric unit of (I). The first independent molecule (with the S1 atom) is shown in red. | |
Fig. 3. Assembly of molecules in the ac plane in (I) mediated by C—H···O (orange dashed lines), C—H···N (blue), C—H···π (purple) and π–π (pink) interactions. | |
Fig. 4. A view in projection down the a axis of the crystal packing in (I) highlighting the stacking of layers along the b axis. |
C18H15NOS | F(000) = 1232 |
Mr = 293.37 | Dx = 1.352 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 4109 reflections |
a = 10.4935 (4) Å | θ = 2.5–29.2° |
b = 23.8464 (8) Å | µ = 0.22 mm−1 |
c = 11.5464 (4) Å | T = 100 K |
β = 93.756 (3)° | Block, colourless |
V = 2883.07 (18) Å3 | 0.25 × 0.20 × 0.15 mm |
Z = 8 |
Agilent SuperNova Dual diffractometer with an Atlas detector | 6427 independent reflections |
Radiation source: SuperNova (Mo) X-ray Source | 4075 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.040 |
Detector resolution: 10.4041 pixels mm-1 | θmax = 27.5°, θmin = 2.5° |
ω scans | h = −13→13 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010) | k = −30→22 |
Tmin = 0.947, Tmax = 0.967 | l = −14→11 |
14916 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.160 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0713P)2 + 0.299P] where P = (Fo2 + 2Fc2)/3 |
6427 reflections | (Δ/σ)max < 0.001 |
409 parameters | Δρmax = 0.56 e Å−3 |
182 restraints | Δρmin = −0.46 e Å−3 |
C18H15NOS | V = 2883.07 (18) Å3 |
Mr = 293.37 | Z = 8 |
Monoclinic, P21/n | Mo Kα radiation |
a = 10.4935 (4) Å | µ = 0.22 mm−1 |
b = 23.8464 (8) Å | T = 100 K |
c = 11.5464 (4) Å | 0.25 × 0.20 × 0.15 mm |
β = 93.756 (3)° |
Agilent SuperNova Dual diffractometer with an Atlas detector | 6427 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010) | 4075 reflections with I > 2σ(I) |
Tmin = 0.947, Tmax = 0.967 | Rint = 0.040 |
14916 measured reflections |
R[F2 > 2σ(F2)] = 0.055 | 182 restraints |
wR(F2) = 0.160 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.56 e Å−3 |
6427 reflections | Δρmin = −0.46 e Å−3 |
409 parameters |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
S1 | 0.30670 (9) | 0.05958 (3) | 0.34043 (8) | 0.0224 (3) | 0.765 (2) |
S2 | 1.08225 (8) | 0.05541 (3) | 0.60970 (7) | 0.0228 (3) | 0.814 (2) |
S1' | 0.2891 (5) | 0.10382 (16) | 0.1135 (4) | 0.0224 (3) | 0.235 (2) |
S2' | 1.1144 (6) | 0.10712 (19) | 0.8273 (5) | 0.0228 (3) | 0.186 (2) |
O1 | 0.83016 (16) | 0.07720 (7) | 0.36269 (14) | 0.0240 (4) | |
O2 | 0.56274 (16) | 0.07794 (7) | 0.59472 (14) | 0.0259 (4) | |
N1 | 0.87096 (18) | 0.13639 (8) | 0.00826 (16) | 0.0182 (4) | |
N2 | 0.52776 (18) | 0.14083 (8) | 0.94581 (16) | 0.0181 (4) | |
C1 | 0.1610 (3) | 0.06381 (10) | 0.2659 (3) | 0.0246 (9) | 0.765 (2) |
H1 | 0.0835 | 0.0521 | 0.2965 | 0.029* | 0.765 (2) |
C2 | 0.1682 (4) | 0.08583 (10) | 0.1576 (3) | 0.0284 (9) | 0.765 (2) |
H2 | 0.0971 | 0.0912 | 0.1035 | 0.034* | 0.765 (2) |
C3 | 0.2925 (5) | 0.09927 (16) | 0.1371 (4) | 0.0253 (14) | 0.765 (2) |
H3 | 0.3144 | 0.1157 | 0.0661 | 0.030* | 0.765 (2) |
C1' | 0.1608 (11) | 0.0803 (2) | 0.1824 (9) | 0.0246 (9) | 0.235 (2) |
H1' | 0.0755 | 0.0803 | 0.1492 | 0.029* | 0.235 (2) |
C2' | 0.1964 (10) | 0.0612 (2) | 0.2923 (9) | 0.0284 (9) | 0.235 (2) |
H2' | 0.1379 | 0.0468 | 0.3442 | 0.034* | 0.235 (2) |
C3' | 0.3256 (10) | 0.0652 (2) | 0.3189 (7) | 0.0253 (14) | 0.235 (2) |
H3' | 0.3678 | 0.0542 | 0.3906 | 0.030* | 0.235 (2) |
C4 | 0.3847 (2) | 0.08728 (9) | 0.22700 (19) | 0.0194 (5) | |
C5 | 0.5200 (2) | 0.09698 (9) | 0.22462 (19) | 0.0176 (5) | |
H5 | 0.5482 | 0.1144 | 0.1569 | 0.021* | |
C6 | 0.6106 (2) | 0.08403 (10) | 0.3082 (2) | 0.0202 (5) | |
H6 | 0.5863 | 0.0667 | 0.3776 | 0.024* | |
C7 | 0.7457 (2) | 0.09599 (9) | 0.29473 (19) | 0.0179 (5) | |
C8 | 0.8360 (2) | 0.04453 (10) | 0.0864 (2) | 0.0245 (6) | |
H8A | 0.8668 | 0.0341 | 0.0111 | 0.037* | |
H8B | 0.7505 | 0.0289 | 0.0934 | 0.037* | |
H8C | 0.8944 | 0.0296 | 0.1487 | 0.037* | |
C9 | 0.8305 (2) | 0.10735 (10) | 0.09594 (19) | 0.0176 (5) | |
C10 | 0.7826 (2) | 0.13304 (9) | 0.19578 (19) | 0.0173 (5) | |
C11 | 0.7760 (2) | 0.19024 (9) | 0.20381 (19) | 0.0168 (5) | |
C12 | 0.7250 (2) | 0.21978 (10) | 0.3063 (2) | 0.0202 (5) | |
H12A | 0.6995 | 0.1920 | 0.3628 | 0.030* | |
H12B | 0.6507 | 0.2425 | 0.2802 | 0.030* | |
H12C | 0.7915 | 0.2441 | 0.3426 | 0.030* | |
C13 | 0.8209 (2) | 0.22287 (9) | 0.11100 (19) | 0.0164 (5) | |
C14 | 0.8211 (2) | 0.28242 (10) | 0.1100 (2) | 0.0204 (5) | |
H14 | 0.7912 | 0.3024 | 0.1740 | 0.024* | |
C15 | 0.8636 (2) | 0.31132 (10) | 0.0179 (2) | 0.0221 (5) | |
H15 | 0.8635 | 0.3512 | 0.0185 | 0.027* | |
C16 | 0.9074 (2) | 0.28255 (10) | −0.0774 (2) | 0.0213 (5) | |
H16 | 0.9358 | 0.3030 | −0.1415 | 0.026* | |
C17 | 0.9096 (2) | 0.22560 (10) | −0.0792 (2) | 0.0198 (5) | |
H17 | 0.9405 | 0.2067 | −0.1441 | 0.024* | |
C18 | 0.8664 (2) | 0.19410 (9) | 0.01481 (19) | 0.0162 (5) | |
C19 | 1.2324 (3) | 0.06405 (10) | 0.6756 (3) | 0.0227 (8) | 0.814 (2) |
H19 | 1.3088 | 0.0523 | 0.6429 | 0.027* | 0.814 (2) |
C20 | 1.2283 (3) | 0.08988 (9) | 0.7808 (3) | 0.0262 (8) | 0.814 (2) |
H20 | 1.3016 | 0.0983 | 0.8304 | 0.031* | 0.814 (2) |
C21 | 1.1044 (5) | 0.10228 (15) | 0.8064 (4) | 0.0231 (12) | 0.814 (2) |
H21 | 1.0851 | 0.1205 | 0.8763 | 0.028* | 0.814 (2) |
C19' | 1.2382 (12) | 0.0828 (3) | 0.7536 (10) | 0.0227 (8) | 0.186 (2) |
H19B | 1.3253 | 0.0851 | 0.7812 | 0.027* | 0.186 (2) |
C20' | 1.1962 (11) | 0.0594 (3) | 0.6493 (9) | 0.0262 (8) | 0.186 (2) |
H20B | 1.2514 | 0.0437 | 0.5959 | 0.031* | 0.186 (2) |
C21' | 1.0652 (12) | 0.0613 (2) | 0.6307 (7) | 0.0231 (12) | 0.186 (2) |
H21B | 1.0189 | 0.0473 | 0.5633 | 0.028* | 0.186 (2) |
C22 | 1.0104 (2) | 0.08626 (9) | 0.72294 (19) | 0.0186 (5) | |
C23 | 0.8752 (2) | 0.09631 (9) | 0.7276 (2) | 0.0172 (5) | |
H23 | 0.8484 | 0.1127 | 0.7970 | 0.021* | |
C24 | 0.7833 (2) | 0.08503 (9) | 0.6447 (2) | 0.0185 (5) | |
H24 | 0.8061 | 0.0684 | 0.5742 | 0.022* | |
C25 | 0.6489 (2) | 0.09748 (9) | 0.6595 (2) | 0.0184 (5) | |
C26 | 0.6714 (2) | 0.22170 (10) | 0.6441 (2) | 0.0211 (5) | |
H26A | 0.6954 | 0.1934 | 0.5880 | 0.032* | |
H26B | 0.7465 | 0.2441 | 0.6692 | 0.032* | |
H26C | 0.6054 | 0.2463 | 0.6078 | 0.032* | |
C27 | 0.6204 (2) | 0.19306 (10) | 0.74765 (19) | 0.0173 (5) | |
C28 | 0.6142 (2) | 0.13577 (9) | 0.75760 (19) | 0.0160 (5) | |
C29 | 0.5674 (2) | 0.11100 (10) | 0.85886 (19) | 0.0176 (5) | |
C30 | 0.5630 (2) | 0.04845 (9) | 0.8706 (2) | 0.0239 (6) | |
H30A | 0.5345 | 0.0386 | 0.9471 | 0.036* | |
H30B | 0.6484 | 0.0329 | 0.8623 | 0.036* | |
H30C | 0.5033 | 0.0329 | 0.8101 | 0.036* | |
C31 | 0.5763 (2) | 0.22622 (9) | 0.84016 (19) | 0.0161 (5) | |
C32 | 0.5758 (2) | 0.28574 (10) | 0.8390 (2) | 0.0201 (5) | |
H32 | 0.6059 | 0.3052 | 0.7744 | 0.024* | |
C33 | 0.5327 (2) | 0.31534 (10) | 0.9295 (2) | 0.0233 (6) | |
H33 | 0.5322 | 0.3552 | 0.9271 | 0.028* | |
C34 | 0.4888 (2) | 0.28715 (10) | 1.0269 (2) | 0.0227 (6) | |
H34 | 0.4601 | 0.3081 | 1.0901 | 0.027* | |
C35 | 0.4877 (2) | 0.22986 (10) | 1.0305 (2) | 0.0203 (5) | |
H35 | 0.4573 | 0.2112 | 1.0960 | 0.024* | |
C36 | 0.5314 (2) | 0.19812 (9) | 0.93734 (19) | 0.0163 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0241 (5) | 0.0243 (5) | 0.0195 (5) | −0.0060 (4) | 0.0075 (3) | −0.0004 (3) |
S2 | 0.0227 (5) | 0.0262 (5) | 0.0201 (4) | 0.0063 (3) | 0.0063 (3) | −0.0009 (3) |
S1' | 0.0241 (5) | 0.0243 (5) | 0.0195 (5) | −0.0060 (4) | 0.0075 (3) | −0.0004 (3) |
S2' | 0.0227 (5) | 0.0262 (5) | 0.0201 (4) | 0.0063 (3) | 0.0063 (3) | −0.0009 (3) |
O1 | 0.0256 (10) | 0.0285 (10) | 0.0174 (9) | 0.0003 (8) | −0.0019 (8) | 0.0032 (7) |
O2 | 0.0213 (9) | 0.0341 (10) | 0.0220 (9) | −0.0001 (8) | −0.0015 (8) | −0.0057 (8) |
N1 | 0.0164 (10) | 0.0207 (10) | 0.0176 (10) | −0.0011 (8) | 0.0014 (8) | −0.0021 (8) |
N2 | 0.0173 (10) | 0.0211 (10) | 0.0160 (10) | 0.0017 (8) | 0.0027 (8) | 0.0009 (8) |
C1 | 0.0109 (15) | 0.0289 (18) | 0.034 (2) | −0.0063 (14) | 0.0056 (16) | −0.0078 (16) |
C2 | 0.0205 (18) | 0.034 (2) | 0.031 (2) | −0.0014 (15) | 0.0037 (16) | 0.0022 (16) |
C3 | 0.023 (2) | 0.035 (2) | 0.018 (3) | −0.0026 (16) | −0.0002 (19) | 0.0067 (18) |
C1' | 0.0109 (15) | 0.0289 (18) | 0.034 (2) | −0.0063 (14) | 0.0056 (16) | −0.0078 (16) |
C2' | 0.0205 (18) | 0.034 (2) | 0.031 (2) | −0.0014 (15) | 0.0037 (16) | 0.0022 (16) |
C3' | 0.023 (2) | 0.035 (2) | 0.018 (3) | −0.0026 (16) | −0.0002 (19) | 0.0067 (18) |
C4 | 0.0207 (13) | 0.0170 (12) | 0.0211 (13) | −0.0017 (10) | 0.0062 (10) | −0.0041 (10) |
C5 | 0.0215 (13) | 0.0170 (11) | 0.0151 (11) | −0.0038 (10) | 0.0071 (10) | −0.0024 (9) |
C6 | 0.0235 (13) | 0.0211 (12) | 0.0168 (12) | −0.0040 (10) | 0.0064 (10) | −0.0020 (10) |
C7 | 0.0234 (13) | 0.0170 (12) | 0.0136 (11) | −0.0003 (10) | 0.0034 (10) | −0.0026 (9) |
C8 | 0.0302 (14) | 0.0206 (13) | 0.0234 (13) | −0.0020 (11) | 0.0065 (11) | −0.0035 (10) |
C9 | 0.0172 (12) | 0.0215 (12) | 0.0141 (11) | −0.0014 (10) | −0.0005 (10) | −0.0014 (9) |
C10 | 0.0129 (12) | 0.0242 (12) | 0.0147 (11) | −0.0028 (10) | 0.0008 (9) | 0.0007 (9) |
C11 | 0.0112 (11) | 0.0236 (12) | 0.0157 (11) | −0.0009 (10) | 0.0003 (9) | −0.0030 (10) |
C12 | 0.0203 (13) | 0.0225 (12) | 0.0183 (12) | 0.0009 (10) | 0.0053 (10) | −0.0037 (10) |
C13 | 0.0114 (11) | 0.0202 (12) | 0.0173 (12) | 0.0001 (9) | −0.0009 (9) | −0.0010 (9) |
C14 | 0.0161 (12) | 0.0215 (13) | 0.0234 (13) | 0.0018 (10) | 0.0002 (10) | −0.0043 (10) |
C15 | 0.0189 (13) | 0.0192 (12) | 0.0279 (14) | 0.0017 (10) | −0.0009 (11) | 0.0047 (10) |
C16 | 0.0169 (13) | 0.0269 (13) | 0.0202 (13) | −0.0002 (10) | 0.0016 (10) | 0.0074 (10) |
C17 | 0.0167 (12) | 0.0260 (13) | 0.0168 (12) | −0.0005 (10) | 0.0030 (10) | 0.0001 (10) |
C18 | 0.0108 (11) | 0.0218 (12) | 0.0159 (12) | −0.0025 (10) | −0.0003 (9) | 0.0000 (9) |
C19 | 0.0129 (15) | 0.0265 (17) | 0.0296 (19) | 0.0053 (13) | 0.0086 (14) | 0.0095 (14) |
C20 | 0.0179 (16) | 0.0256 (16) | 0.035 (2) | 0.0010 (13) | −0.0009 (15) | −0.0017 (14) |
C21 | 0.024 (2) | 0.0246 (19) | 0.020 (2) | 0.0005 (14) | −0.0058 (17) | −0.0020 (16) |
C19' | 0.0129 (15) | 0.0265 (17) | 0.0296 (19) | 0.0053 (13) | 0.0086 (14) | 0.0095 (14) |
C20' | 0.0179 (16) | 0.0256 (16) | 0.035 (2) | 0.0010 (13) | −0.0009 (15) | −0.0017 (14) |
C21' | 0.024 (2) | 0.0246 (19) | 0.020 (2) | 0.0005 (14) | −0.0058 (17) | −0.0020 (16) |
C22 | 0.0215 (13) | 0.0156 (11) | 0.0192 (12) | 0.0012 (10) | 0.0052 (10) | 0.0023 (9) |
C23 | 0.0202 (13) | 0.0155 (11) | 0.0164 (12) | −0.0013 (10) | 0.0059 (10) | 0.0014 (9) |
C24 | 0.0197 (13) | 0.0208 (12) | 0.0154 (12) | 0.0019 (10) | 0.0038 (10) | 0.0001 (10) |
C25 | 0.0200 (13) | 0.0197 (12) | 0.0155 (12) | 0.0002 (10) | 0.0025 (10) | 0.0031 (9) |
C26 | 0.0209 (13) | 0.0250 (13) | 0.0179 (12) | −0.0004 (10) | 0.0043 (10) | 0.0030 (10) |
C27 | 0.0119 (12) | 0.0227 (12) | 0.0171 (12) | −0.0015 (10) | −0.0001 (9) | 0.0032 (10) |
C28 | 0.0114 (11) | 0.0228 (12) | 0.0141 (11) | 0.0039 (9) | 0.0016 (9) | −0.0001 (9) |
C29 | 0.0143 (12) | 0.0218 (12) | 0.0168 (12) | 0.0016 (10) | 0.0012 (9) | 0.0023 (10) |
C30 | 0.0313 (14) | 0.0176 (12) | 0.0232 (13) | 0.0005 (11) | 0.0064 (11) | 0.0031 (10) |
C31 | 0.0108 (11) | 0.0196 (12) | 0.0180 (12) | 0.0007 (9) | 0.0017 (9) | −0.0009 (9) |
C32 | 0.0178 (13) | 0.0209 (12) | 0.0216 (13) | −0.0017 (10) | 0.0013 (10) | 0.0032 (10) |
C33 | 0.0179 (13) | 0.0189 (12) | 0.0330 (15) | 0.0002 (10) | 0.0011 (11) | −0.0040 (11) |
C34 | 0.0179 (13) | 0.0265 (13) | 0.0237 (13) | 0.0011 (10) | 0.0016 (10) | −0.0090 (11) |
C35 | 0.0167 (12) | 0.0250 (13) | 0.0195 (13) | 0.0024 (10) | 0.0027 (10) | −0.0010 (10) |
C36 | 0.0109 (11) | 0.0218 (12) | 0.0163 (12) | 0.0010 (9) | 0.0011 (9) | 0.0003 (10) |
S1—C1 | 1.708 (3) | C14—H14 | 0.9500 |
S1—C4 | 1.721 (2) | C15—C16 | 1.399 (3) |
S2—C22 | 1.717 (2) | C15—H15 | 0.9500 |
S2—C19 | 1.717 (3) | C16—C17 | 1.358 (3) |
S1'—C4 | 1.646 (5) | C16—H16 | 0.9500 |
S1'—C1' | 1.704 (8) | C17—C18 | 1.418 (3) |
S2'—C22 | 1.649 (6) | C17—H17 | 0.9500 |
S2'—C19' | 1.700 (8) | C19—C20 | 1.365 (4) |
O1—C7 | 1.229 (3) | C19—H19 | 0.9500 |
O2—C25 | 1.227 (3) | C20—C21 | 1.384 (5) |
N1—C9 | 1.319 (3) | C20—H20 | 0.9500 |
N1—C18 | 1.379 (3) | C21—C22 | 1.387 (4) |
N2—C29 | 1.320 (3) | C21—H21 | 0.9500 |
N2—C36 | 1.370 (3) | C19'—C20' | 1.374 (8) |
C1—C2 | 1.362 (4) | C19'—H19B | 0.9500 |
C1—H1 | 0.9500 | C20'—C21' | 1.379 (8) |
C2—C3 | 1.379 (5) | C20'—H20B | 0.9500 |
C2—H2 | 0.9500 | C21'—C22 | 1.378 (7) |
C3—C4 | 1.401 (5) | C21'—H21B | 0.9500 |
C3—H3 | 0.9500 | C22—C23 | 1.443 (3) |
C1'—C2' | 1.377 (8) | C23—C24 | 1.341 (3) |
C1'—H1' | 0.9500 | C23—H23 | 0.9500 |
C2'—C3' | 1.373 (8) | C24—C25 | 1.461 (3) |
C2'—H2' | 0.9500 | C24—H24 | 0.9500 |
C3'—C4 | 1.369 (7) | C25—C28 | 1.517 (3) |
C3'—H3' | 0.9500 | C26—C27 | 1.505 (3) |
C4—C5 | 1.440 (3) | C26—H26A | 0.9800 |
C5—C6 | 1.345 (3) | C26—H26B | 0.9800 |
C5—H5 | 0.9500 | C26—H26C | 0.9800 |
C6—C7 | 1.465 (3) | C27—C28 | 1.373 (3) |
C6—H6 | 0.9500 | C27—C31 | 1.430 (3) |
C7—C10 | 1.515 (3) | C28—C29 | 1.426 (3) |
C8—C9 | 1.503 (3) | C29—C30 | 1.499 (3) |
C8—H8A | 0.9800 | C30—H30A | 0.9800 |
C8—H8B | 0.9800 | C30—H30B | 0.9800 |
C8—H8C | 0.9800 | C30—H30C | 0.9800 |
C9—C10 | 1.426 (3) | C31—C36 | 1.414 (3) |
C10—C11 | 1.369 (3) | C31—C32 | 1.420 (3) |
C11—C13 | 1.429 (3) | C32—C33 | 1.362 (3) |
C11—C12 | 1.505 (3) | C32—H32 | 0.9500 |
C12—H12A | 0.9800 | C33—C34 | 1.413 (3) |
C12—H12B | 0.9800 | C33—H33 | 0.9500 |
C12—H12C | 0.9800 | C34—C35 | 1.367 (3) |
C13—C18 | 1.415 (3) | C34—H34 | 0.9500 |
C13—C14 | 1.420 (3) | C35—C36 | 1.416 (3) |
C14—C15 | 1.367 (3) | C35—H35 | 0.9500 |
C1—S1—C4 | 92.77 (15) | N1—C18—C13 | 122.8 (2) |
C22—S2—C19 | 92.72 (14) | N1—C18—C17 | 118.2 (2) |
C4—S1'—C1' | 90.5 (5) | C13—C18—C17 | 119.0 (2) |
C22—S2'—C19' | 91.3 (5) | C20—C19—S2 | 111.5 (2) |
C9—N1—C18 | 117.9 (2) | C20—C19—H19 | 124.2 |
C29—N2—C36 | 118.1 (2) | S2—C19—H19 | 124.2 |
C2—C1—S1 | 112.5 (3) | C19—C20—C21 | 111.8 (3) |
C2—C1—H1 | 123.7 | C19—C20—H20 | 124.1 |
S1—C1—H1 | 123.7 | C21—C20—H20 | 124.1 |
C1—C2—C3 | 110.9 (3) | C22—C21—C20 | 115.3 (4) |
C1—C2—H2 | 124.5 | C22—C21—H21 | 122.3 |
C3—C2—H2 | 124.5 | C20—C21—H21 | 122.3 |
C2—C3—C4 | 116.1 (4) | C20'—C19'—S2' | 111.5 (8) |
C2—C3—H3 | 121.9 | C20'—C19'—H19B | 124.3 |
C4—C3—H3 | 121.9 | S2'—C19'—H19B | 124.3 |
C2'—C1'—S1' | 111.3 (8) | C19'—C20'—C21' | 112.5 (7) |
C2'—C1'—H1' | 124.3 | C19'—C20'—H20B | 123.8 |
S1'—C1'—H1' | 124.3 | C21'—C20'—H20B | 123.8 |
C3'—C2'—C1' | 112.8 (7) | C20'—C21'—C22 | 110.8 (6) |
C3'—C2'—H2' | 123.6 | C20'—C21'—H21B | 124.6 |
C1'—C2'—H2' | 123.6 | C22—C21'—H21B | 124.6 |
C2'—C3'—C4 | 110.2 (6) | C21—C22—C21' | 110.0 (6) |
C2'—C3'—H3' | 124.9 | C21—C22—C23 | 125.8 (3) |
C4—C3'—H3' | 124.9 | C21'—C22—C23 | 124.2 (6) |
C3—C4—C3' | 109.1 (6) | C21—C22—S2' | 3.9 (4) |
C3—C4—C5 | 125.9 (3) | C21'—C22—S2' | 113.9 (5) |
C3'—C4—C5 | 125.0 (5) | C23—C22—S2' | 121.9 (3) |
C3—C4—S1' | 6.1 (4) | C21—C22—S2 | 108.6 (3) |
C3'—C4—S1' | 115.2 (5) | C21'—C22—S2 | 1.4 (5) |
C5—C4—S1' | 119.8 (3) | C23—C22—S2 | 125.55 (17) |
C3—C4—S1 | 107.6 (3) | S2'—C22—S2 | 112.5 (3) |
C3'—C4—S1 | 1.5 (5) | C24—C23—C22 | 127.1 (2) |
C5—C4—S1 | 126.48 (17) | C24—C23—H23 | 116.5 |
S1'—C4—S1 | 113.7 (2) | C22—C23—H23 | 116.5 |
C6—C5—C4 | 126.9 (2) | C23—C24—C25 | 122.0 (2) |
C6—C5—H5 | 116.6 | C23—C24—H24 | 119.0 |
C4—C5—H5 | 116.6 | C25—C24—H24 | 119.0 |
C5—C6—C7 | 121.5 (2) | O2—C25—C24 | 122.0 (2) |
C5—C6—H6 | 119.3 | O2—C25—C28 | 118.7 (2) |
C7—C6—H6 | 119.3 | C24—C25—C28 | 119.36 (19) |
O1—C7—C6 | 121.6 (2) | C27—C26—H26A | 109.5 |
O1—C7—C10 | 119.0 (2) | C27—C26—H26B | 109.5 |
C6—C7—C10 | 119.41 (19) | H26A—C26—H26B | 109.5 |
C9—C8—H8A | 109.5 | C27—C26—H26C | 109.5 |
C9—C8—H8B | 109.5 | H26A—C26—H26C | 109.5 |
H8A—C8—H8B | 109.5 | H26B—C26—H26C | 109.5 |
C9—C8—H8C | 109.5 | C28—C27—C31 | 117.9 (2) |
H8A—C8—H8C | 109.5 | C28—C27—C26 | 122.6 (2) |
H8B—C8—H8C | 109.5 | C31—C27—C26 | 119.4 (2) |
N1—C9—C10 | 122.9 (2) | C27—C28—C29 | 120.1 (2) |
N1—C9—C8 | 116.8 (2) | C27—C28—C25 | 121.4 (2) |
C10—C9—C8 | 120.3 (2) | C29—C28—C25 | 118.4 (2) |
C11—C10—C9 | 120.3 (2) | N2—C29—C28 | 122.9 (2) |
C11—C10—C7 | 120.9 (2) | N2—C29—C30 | 117.0 (2) |
C9—C10—C7 | 118.7 (2) | C28—C29—C30 | 120.1 (2) |
C10—C11—C13 | 118.1 (2) | C29—C30—H30A | 109.5 |
C10—C11—C12 | 122.8 (2) | C29—C30—H30B | 109.5 |
C13—C11—C12 | 119.1 (2) | H30A—C30—H30B | 109.5 |
C11—C12—H12A | 109.5 | C29—C30—H30C | 109.5 |
C11—C12—H12B | 109.5 | H30A—C30—H30C | 109.5 |
H12A—C12—H12B | 109.5 | H30B—C30—H30C | 109.5 |
C11—C12—H12C | 109.5 | C36—C31—C32 | 118.7 (2) |
H12A—C12—H12C | 109.5 | C36—C31—C27 | 118.2 (2) |
H12B—C12—H12C | 109.5 | C32—C31—C27 | 123.2 (2) |
C18—C13—C14 | 118.5 (2) | C33—C32—C31 | 120.8 (2) |
C18—C13—C11 | 118.0 (2) | C33—C32—H32 | 119.6 |
C14—C13—C11 | 123.5 (2) | C31—C32—H32 | 119.6 |
C15—C14—C13 | 120.7 (2) | C32—C33—C34 | 120.4 (2) |
C15—C14—H14 | 119.6 | C32—C33—H33 | 119.8 |
C13—C14—H14 | 119.6 | C34—C33—H33 | 119.8 |
C14—C15—C16 | 120.4 (2) | C35—C34—C33 | 120.3 (2) |
C14—C15—H15 | 119.8 | C35—C34—H34 | 119.9 |
C16—C15—H15 | 119.8 | C33—C34—H34 | 119.9 |
C17—C16—C15 | 120.6 (2) | C34—C35—C36 | 120.5 (2) |
C17—C16—H16 | 119.7 | C34—C35—H35 | 119.8 |
C15—C16—H16 | 119.7 | C36—C35—H35 | 119.8 |
C16—C17—C18 | 120.8 (2) | N2—C36—C31 | 122.8 (2) |
C16—C17—H17 | 119.6 | N2—C36—C35 | 117.8 (2) |
C18—C17—H17 | 119.6 | C31—C36—C35 | 119.4 (2) |
C4—S1—C1—C2 | −0.36 (11) | C22—S2—C19—C20 | −0.20 (10) |
S1—C1—C2—C3 | −0.33 (19) | S2—C19—C20—C21 | −0.04 (19) |
C1—C2—C3—C4 | 1.1 (3) | C19—C20—C21—C22 | 0.3 (3) |
C4—S1'—C1'—C2' | 1.0 (4) | C22—S2'—C19'—C20' | 0.5 (4) |
S1'—C1'—C2'—C3' | −0.7 (6) | S2'—C19'—C20'—C21' | −0.2 (6) |
C1'—C2'—C3'—C4 | −0.2 (6) | C19'—C20'—C21'—C22 | −0.3 (6) |
C2—C3—C4—C3' | −1.4 (4) | C20—C21—C22—C21' | −0.5 (4) |
C2—C3—C4—C5 | 179.2 (2) | C20—C21—C22—C23 | −177.6 (2) |
C2—C3—C4—S1 | −1.3 (3) | C20—C21—C22—S2 | −0.5 (3) |
C2'—C3'—C4—C3 | 0.9 (5) | C20'—C21'—C22—C21 | 0.4 (5) |
C2'—C3'—C4—C5 | −179.6 (3) | C20'—C21'—C22—C23 | 177.6 (3) |
C2'—C3'—C4—S1' | 1.0 (5) | C20'—C21'—C22—S2' | 0.6 (5) |
C2'—C3'—C4—S1 | −1 (8) | C20'—C21'—C22—S2 | −1 (8) |
C1'—S1'—C4—C3 | −1 (2) | C19'—S2'—C22—C21 | 2 (4) |
C1'—S1'—C4—C3' | −1.2 (4) | C19'—S2'—C22—C21' | −0.6 (4) |
C1'—S1'—C4—C5 | 179.4 (2) | C19'—S2'—C22—C23 | −177.7 (2) |
C1'—S1'—C4—S1 | −1.1 (3) | C19'—S2'—C22—S2 | −0.6 (3) |
C1—S1—C4—C3 | 0.9 (2) | C19—S2—C22—C21 | 0.38 (19) |
C1—S1—C4—C5 | −179.6 (2) | C19—S2—C22—C23 | 177.5 (2) |
C1—S1—C4—S1' | 0.96 (18) | C19—S2—C22—S2' | 0.55 (19) |
C3—C4—C5—C6 | −177.5 (3) | C21—C22—C23—C24 | 174.7 (3) |
C3'—C4—C5—C6 | 3.1 (4) | C21'—C22—C23—C24 | −2.0 (4) |
S1'—C4—C5—C6 | −177.5 (2) | S2'—C22—C23—C24 | 174.8 (2) |
S1—C4—C5—C6 | 3.1 (4) | S2—C22—C23—C24 | −2.0 (3) |
C4—C5—C6—C7 | 179.7 (2) | C22—C23—C24—C25 | −179.7 (2) |
C5—C6—C7—O1 | −169.4 (2) | C23—C24—C25—O2 | −165.9 (2) |
C5—C6—C7—C10 | 11.5 (3) | C23—C24—C25—C28 | 14.3 (3) |
C18—N1—C9—C10 | 0.1 (3) | C31—C27—C28—C29 | −1.2 (3) |
C18—N1—C9—C8 | 179.80 (19) | C26—C27—C28—C29 | 178.7 (2) |
N1—C9—C10—C11 | 0.5 (3) | C31—C27—C28—C25 | 175.06 (19) |
C8—C9—C10—C11 | −179.1 (2) | C26—C27—C28—C25 | −5.0 (3) |
N1—C9—C10—C7 | −176.5 (2) | O2—C25—C28—C27 | −98.7 (3) |
C8—C9—C10—C7 | 3.9 (3) | C24—C25—C28—C27 | 81.1 (3) |
O1—C7—C10—C11 | −98.3 (3) | O2—C25—C28—C29 | 77.7 (3) |
C6—C7—C10—C11 | 80.8 (3) | C24—C25—C28—C29 | −102.5 (3) |
O1—C7—C10—C9 | 78.7 (3) | C36—N2—C29—C28 | 0.4 (3) |
C6—C7—C10—C9 | −102.2 (3) | C36—N2—C29—C30 | 179.72 (19) |
C9—C10—C11—C13 | −1.4 (3) | C27—C28—C29—N2 | 0.4 (3) |
C7—C10—C11—C13 | 175.53 (19) | C25—C28—C29—N2 | −176.0 (2) |
C9—C10—C11—C12 | 179.3 (2) | C27—C28—C29—C30 | −178.8 (2) |
C7—C10—C11—C12 | −3.8 (3) | C25—C28—C29—C30 | 4.7 (3) |
C10—C11—C13—C18 | 1.7 (3) | C28—C27—C31—C36 | 1.2 (3) |
C12—C11—C13—C18 | −178.99 (19) | C26—C27—C31—C36 | −178.75 (19) |
C10—C11—C13—C14 | −178.9 (2) | C28—C27—C31—C32 | −178.9 (2) |
C12—C11—C13—C14 | 0.4 (3) | C26—C27—C31—C32 | 1.2 (3) |
C18—C13—C14—C15 | 0.3 (3) | C36—C31—C32—C33 | −0.1 (3) |
C11—C13—C14—C15 | −179.1 (2) | C27—C31—C32—C33 | 180.0 (2) |
C13—C14—C15—C16 | 0.3 (3) | C31—C32—C33—C34 | 0.6 (3) |
C14—C15—C16—C17 | −0.8 (3) | C32—C33—C34—C35 | −0.9 (3) |
C15—C16—C17—C18 | 0.7 (3) | C33—C34—C35—C36 | 0.6 (3) |
C9—N1—C18—C13 | 0.2 (3) | C29—N2—C36—C31 | −0.4 (3) |
C9—N1—C18—C17 | −179.94 (19) | C29—N2—C36—C35 | 179.47 (19) |
C14—C13—C18—N1 | 179.5 (2) | C32—C31—C36—N2 | 179.7 (2) |
C11—C13—C18—N1 | −1.1 (3) | C27—C31—C36—N2 | −0.4 (3) |
C14—C13—C18—C17 | −0.4 (3) | C32—C31—C36—C35 | −0.2 (3) |
C11—C13—C18—C17 | 179.03 (19) | C27—C31—C36—C35 | 179.71 (19) |
C16—C17—C18—N1 | −180.0 (2) | C34—C35—C36—N2 | −179.9 (2) |
C16—C17—C18—C13 | −0.1 (3) | C34—C35—C36—C31 | 0.0 (3) |
Cg1 and Cg2 are the centroids of the C31–C36 and C13–C18 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···N2i | 0.95 | 2.51 | 3.391 (3) | 154 |
C6—H6···O2 | 0.95 | 2.55 | 3.382 (3) | 146 |
C23—H23···N1ii | 0.95 | 2.50 | 3.382 (3) | 154 |
C24—H24···O1 | 0.95 | 2.48 | 3.330 (3) | 149 |
C12—H12c···Cg1iii | 0.98 | 2.67 | 142 | 4 (1) |
C26—H26c···Cg2iv | 0.98 | 2.67 | 143 | 4 (1) |
Symmetry codes: (i) x, y, z−1; (ii) x, y, z+1; (iii) x−1/2, −y−1/2, z−3/2; (iv) x−3/2, −y−1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C18H15NOS |
Mr | 293.37 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 100 |
a, b, c (Å) | 10.4935 (4), 23.8464 (8), 11.5464 (4) |
β (°) | 93.756 (3) |
V (Å3) | 2883.07 (18) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.22 |
Crystal size (mm) | 0.25 × 0.20 × 0.15 |
Data collection | |
Diffractometer | Agilent SuperNova Dual diffractometer with an Atlas detector |
Absorption correction | Multi-scan (CrysAlis PRO; Agilent, 2010) |
Tmin, Tmax | 0.947, 0.967 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14916, 6427, 4075 |
Rint | 0.040 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.160, 1.03 |
No. of reflections | 6427 |
No. of parameters | 409 |
No. of restraints | 182 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.56, −0.46 |
Computer programs: CrysAlis PRO (Agilent, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), DIAMOND (Brandenburg, 2006) and Qmol (Gans & Shalloway, 2001), publCIF (Westrip, 2010).
Cg1 and Cg2 are the centroids of the C31–C36 and C13–C18 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···N2i | 0.95 | 2.51 | 3.391 (3) | 154 |
C6—H6···O2 | 0.95 | 2.55 | 3.382 (3) | 146 |
C23—H23···N1ii | 0.95 | 2.50 | 3.382 (3) | 154 |
C24—H24···O1 | 0.95 | 2.48 | 3.330 (3) | 149 |
C12—H12c···Cg1iii | 0.98 | 2.67 | 142 | 3.499 (2) |
C26—H26c···Cg2iv | 0.98 | 2.67 | 143 | 3.503 (2) |
Symmetry codes: (i) x, y, z−1; (ii) x, y, z+1; (iii) x−1/2, −y−1/2, z−3/2; (iv) x−3/2, −y−1/2, z−1/2. |
Footnotes
†Additional correspondence author, e-mail: juliebhavana@yahoo.co.in.
Acknowledgements
PB acknowledges the Department of Science and Technology (DST), India, for a research grant (SR/FTP/CS-57/2007). The authors also thank the University of Malaya for support of the crystallographic facility.
References
Agilent (2010). CrysAlis PRO. Agilent Technologies, Yarnton, England. Google Scholar
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Dimmock, J. R., Elias, D. W., Beazely, M. A. & Kandepu, N. M. (1999). Curr. Med. Chem. 6, 1125–1149. Web of Science PubMed CAS Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Gans, J. & Shalloway, D. (2001). J. Mol. Graph. Model. 19, 557–559. Web of Science CrossRef PubMed CAS Google Scholar
Kalluraya, B. & Sreenivasa, S. (1998). Farmaco, 53, 399–404. Web of Science CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Siddiqui, Z. B., Asad, M. & Praveen, S. (2008). Med. Chem. Res. 17, 318–325. CrossRef CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Xiang, W., Tiekink, E. R. T., Iouri, K., Nikolai, K. & Mei, L. G. (2006). Eur. J. Pharm. Sci. 27, 175–187. Web of Science PubMed Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Chalcone derivatives have attracted wide attention owing to their occurrence in natural products and biologically active compounds (Dimmock et al., 1999; Siddiqui et al., 2008). Quinoline chalcone analogues have also gained notice due to their bioactivities such as anti-plasmodial, anti-microbial, anti-malarial and anti-cancer activities (Kalluraya & Sreenivasa, 1998; Xiang et al., 2006). It was in this context that the title compound, (I), was investigated.
Two independent molecules comprise the crystallographic asymmetric unit of (I), Fig. 1, and as may be seen from Fig. 2, the molecular conformations are almost identical with a minor variation in the relative orientations of the terminal thiophenyl rings. The 3-(thiophen-2-yl)prop-2-en-1-one residue is almost normal to the least-squares plane through the quinolin-3-yl group and three bound C substituents (r.m.s. deviations = 0.028 and 0.035 Å, respectively), i.e. 13 non-C atoms. This conformation is reflected in the C6—C7—C10—C9 and C24—C25—C28—C27 torsion angles of -102.2 (3) and 81.1 (3) °, respectively. With reference to the aforementioned quinolin-3-yl plane, the carbonyl-O lies to one side and the remaining atoms of the 3-(thiophen-2-yl)prop-2-en-1-one residue to the other. The dihedral angles formed between the quinolin-3-yl and thiophen-2-yl rings are 87.70 (11) and 83.85 (10) °, respectively. The conformation about the ethene bond is E [C5═C6 = 1.345 (3) Å, and C23═C24 = 1.341 (3) Å].
In the crystal packing, supramolecular layers are formed in the ac plane owing to a combination of C—H···O, C—H···N, C—H···π and π–π interactions, Table 1 and Fig. 3. The two independent molecules comprising the asymmetric unit are linked via the C—H···O interactions, to form an eight-membered {···O═C2H}2 synthon. These are linked into a supramolecular chain along the c axis by C—H···N and π–π interactions. The C—H···π contacts extend in the a direction. Layers stack along the b axis as illustrated in Fig. 4.