organic compounds
Ethyl 2-[4-(1,3-benzothiazol-2-yl)anilino]acetate
aSchool of Chemical and Materials Engineering, Huangshi Institute of Technology, Huangshi 435003, People's Republic of China
*Correspondence e-mail: zy0340907@yahoo.com.cn
In the title compound, C17H16N2O2S, the dihedral angle between the benzothiazole ring system and the benzene ring is 1.20 (2)°. The substituted amino substituent is in an extended conformation with an N—C—C—O torsion angle of 179.4 (3)°. In the pairs of molecules are connected by intermolecular N—H⋯O and weak C—H⋯O hydrogen bonds, forming centrosymmetric dimers.
Related literature
For background to thioflavin T (ThT), a benzothiazole dye that exhibits enhanced fluorescence upon binding to amyloid fibrils, and its derivatives, see: Kung et al. (2001); Qu et al. (2007); Zhang & Zhao (2009). For the synthesis, see: Stephenson et al. (2007).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 2007); cell SAINT-Plus (Bruker, 2007); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Supporting information
https://doi.org/10.1107/S1600536810029442/lh5087sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810029442/lh5087Isup2.hkl
Compound (I) was synthesized according to the method described by Stephenson et al. (2007). Pale yellow single crystals suitable for an X-ray diffraction study were obtained by slow evaporation of an methanol solution.
All H atoms were placed in idealized positions [C—H(methyl)=0.96 Å, 0.97Å (methylene) and 0.93 Å (aromatic),with Uiso(H)= 1.5Ueq(methyl C) 1.2Ueq(other C). N-bounded hydrogen atom was found from the difference map and refined with the restraint of N—H = 0.86 (1)Å and Uiso(H) = 1.2 Ueq(N).
Thioflavin T (ThT) is a benzothiazole dye that exhibits enhanced fluorescence upon binding to amyloid fibrils and is commonly used to diagnose amyloid fibrils, both ex vivo and in vitro. Many derivatives of thioflavin T have been synthesized and evaluated recently (Kung et al., 2001; Qu et al., 2007; Zhang, et al., 2009). We are interested in developing fluorescent probes that are expected to bind to hydrophobic sites in proteins. With this in mind, the title compound, (I), was synthesized and we reported the
herein.In the molecular structure (Fig. 1), the dihedral angle between the benzothiazole ring system and the benzene ring is 1.20 (2)°. The substituted amino substituent is in an extended conformation with an N—C—C—O torsion angle of 179.4 (3)°. In the
pairs of molecules are connected by intermolecular N—H···O and weak C-H···O hydrogen bonds to form centrosymmetric dimers (Fig. 2).For background to thioflavin T (ThT), a benzothiazole dye that exhibits enhanced fluorescence upon binding to amyloid fibrils, see: Kung et al. (2001); Qu et al. (2007); Zhang & Zhao (2009).
Data collection: SMART (Bruker, 2007); cell
SAINT-Plus (Bruker, 2007); data reduction: SAINT-Plus (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. The molecular structure of (I), with displacement ellipsoids drawn at the 50% probability level. | |
Fig. 2. Part of the crystal structure of (I) showing hydrogen bonds as dashed lines. |
C17H16N2O2S | F(000) = 656 |
Mr = 312.38 | Dx = 1.343 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 3368 reflections |
a = 5.6303 (1) Å | θ = 2.5–26.1° |
b = 26.1604 (5) Å | µ = 0.22 mm−1 |
c = 10.5989 (2) Å | T = 298 K |
β = 98.294 (1)° | Block, pale-yellow |
V = 1544.79 (5) Å3 | 0.36 × 0.24 × 0.21 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | 3808 independent reflections |
Radiation source: fine-focus sealed tube | 3015 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.076 |
φ and ω scans | θmax = 28.3°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −7→6 |
Tmin = 0.926, Tmax = 0.956 | k = −34→34 |
11631 measured reflections | l = −10→14 |
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)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.145 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0584P)2 + 0.2785P] where P = (Fo2 + 2Fc2)/3 |
3808 reflections | (Δ/σ)max < 0.001 |
203 parameters | Δρmax = 0.39 e Å−3 |
1 restraint | Δρmin = −0.30 e Å−3 |
C17H16N2O2S | V = 1544.79 (5) Å3 |
Mr = 312.38 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 5.6303 (1) Å | µ = 0.22 mm−1 |
b = 26.1604 (5) Å | T = 298 K |
c = 10.5989 (2) Å | 0.36 × 0.24 × 0.21 mm |
β = 98.294 (1)° |
Bruker SMART CCD area-detector diffractometer | 3808 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 3015 reflections with I > 2σ(I) |
Tmin = 0.926, Tmax = 0.956 | Rint = 0.076 |
11631 measured reflections |
R[F2 > 2σ(F2)] = 0.058 | 1 restraint |
wR(F2) = 0.145 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.39 e Å−3 |
3808 reflections | Δρmin = −0.30 e Å−3 |
203 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.4095 (4) | 0.16282 (7) | 1.27189 (19) | 0.0459 (4) | |
C2 | 0.5567 (4) | 0.18305 (9) | 1.3771 (2) | 0.0584 (6) | |
H2 | 0.7050 | 0.1685 | 1.4067 | 0.070* | |
C3 | 0.4757 (5) | 0.22514 (9) | 1.4357 (2) | 0.0624 (6) | |
H3 | 0.5712 | 0.2397 | 1.5054 | 0.075* | |
C4 | 0.2521 (5) | 0.24629 (8) | 1.3919 (2) | 0.0614 (6) | |
H4 | 0.2007 | 0.2748 | 1.4330 | 0.074* | |
C5 | 0.1066 (4) | 0.22608 (8) | 1.2896 (2) | 0.0552 (5) | |
H5 | −0.0426 | 0.2406 | 1.2618 | 0.066* | |
C6 | 0.1840 (3) | 0.18348 (7) | 1.22724 (19) | 0.0429 (4) | |
C7 | 0.1778 (3) | 0.12057 (7) | 1.08723 (18) | 0.0388 (4) | |
C8 | 0.0933 (3) | 0.08695 (7) | 0.98019 (17) | 0.0383 (4) | |
C9 | 0.2312 (3) | 0.04687 (7) | 0.94479 (19) | 0.0459 (5) | |
H9 | 0.3815 | 0.0408 | 0.9915 | 0.055* | |
C10 | 0.1514 (3) | 0.01576 (7) | 0.84224 (19) | 0.0461 (5) | |
H10 | 0.2472 | −0.0110 | 0.8214 | 0.055* | |
C11 | −0.0722 (3) | 0.02423 (7) | 0.76967 (18) | 0.0404 (4) | |
C12 | −0.2144 (3) | 0.06424 (7) | 0.80651 (19) | 0.0444 (4) | |
H12 | −0.3657 | 0.0701 | 0.7608 | 0.053* | |
C13 | −0.1326 (3) | 0.09459 (7) | 0.90894 (19) | 0.0440 (4) | |
H13 | −0.2295 | 0.1209 | 0.9315 | 0.053* | |
C14 | −0.0362 (3) | −0.04854 (7) | 0.62537 (19) | 0.0448 (4) | |
H14A | −0.0175 | −0.0734 | 0.6941 | 0.054* | |
H14B | 0.1222 | −0.0394 | 0.6068 | 0.054* | |
C15 | −0.1818 (3) | −0.07146 (7) | 0.50852 (19) | 0.0439 (4) | |
C16 | −0.1958 (4) | −0.13779 (8) | 0.3566 (2) | 0.0503 (5) | |
H16A | −0.2157 | −0.1138 | 0.2860 | 0.060* | |
H16B | −0.3530 | −0.1502 | 0.3694 | 0.060* | |
C17 | −0.0407 (4) | −0.18121 (8) | 0.3288 (2) | 0.0621 (6) | |
H17A | 0.1178 | −0.1688 | 0.3228 | 0.093* | |
H17B | −0.1070 | −0.1968 | 0.2495 | 0.093* | |
H17C | −0.0329 | −0.2060 | 0.3961 | 0.093* | |
N1 | 0.0567 (3) | 0.15892 (6) | 1.12304 (15) | 0.0441 (4) | |
N2 | −0.1552 (3) | −0.00386 (7) | 0.66362 (18) | 0.0538 (5) | |
H2A | −0.294 (2) | 0.0014 (8) | 0.622 (2) | 0.065* | |
O1 | −0.0780 (3) | −0.11295 (5) | 0.47181 (14) | 0.0506 (4) | |
O2 | −0.3671 (3) | −0.05410 (6) | 0.45639 (16) | 0.0655 (5) | |
S1 | 0.46125 (9) | 0.11103 (2) | 1.17793 (6) | 0.05496 (19) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0511 (11) | 0.0454 (10) | 0.0419 (11) | −0.0041 (8) | 0.0096 (9) | −0.0032 (8) |
C2 | 0.0616 (13) | 0.0634 (13) | 0.0489 (13) | −0.0079 (10) | 0.0030 (10) | −0.0080 (10) |
C3 | 0.0821 (16) | 0.0581 (13) | 0.0474 (13) | −0.0199 (12) | 0.0104 (11) | −0.0098 (10) |
C4 | 0.0927 (17) | 0.0426 (11) | 0.0531 (13) | −0.0085 (11) | 0.0250 (13) | −0.0090 (10) |
C5 | 0.0695 (13) | 0.0426 (11) | 0.0554 (13) | 0.0028 (9) | 0.0160 (11) | −0.0009 (10) |
C6 | 0.0519 (11) | 0.0375 (9) | 0.0409 (10) | −0.0028 (8) | 0.0121 (8) | 0.0019 (8) |
C7 | 0.0396 (9) | 0.0392 (9) | 0.0374 (10) | 0.0001 (7) | 0.0049 (7) | 0.0034 (7) |
C8 | 0.0394 (9) | 0.0394 (9) | 0.0362 (10) | −0.0009 (7) | 0.0056 (7) | 0.0017 (7) |
C9 | 0.0423 (10) | 0.0463 (10) | 0.0463 (11) | 0.0070 (8) | −0.0032 (8) | −0.0016 (9) |
C10 | 0.0485 (10) | 0.0402 (10) | 0.0476 (12) | 0.0084 (8) | 0.0004 (9) | −0.0051 (8) |
C11 | 0.0428 (9) | 0.0380 (9) | 0.0399 (10) | −0.0026 (7) | 0.0038 (8) | 0.0003 (8) |
C12 | 0.0364 (9) | 0.0493 (10) | 0.0459 (11) | 0.0039 (7) | 0.0011 (8) | −0.0025 (9) |
C13 | 0.0422 (10) | 0.0439 (10) | 0.0463 (11) | 0.0056 (8) | 0.0073 (8) | −0.0023 (8) |
C14 | 0.0470 (10) | 0.0422 (10) | 0.0432 (11) | 0.0000 (8) | 0.0001 (8) | −0.0022 (8) |
C15 | 0.0479 (10) | 0.0413 (10) | 0.0421 (11) | −0.0022 (8) | 0.0051 (8) | −0.0011 (8) |
C16 | 0.0563 (12) | 0.0487 (11) | 0.0455 (12) | −0.0081 (9) | 0.0052 (9) | −0.0084 (9) |
C17 | 0.0786 (15) | 0.0489 (12) | 0.0609 (15) | −0.0035 (11) | 0.0173 (12) | −0.0134 (11) |
N1 | 0.0489 (9) | 0.0400 (8) | 0.0430 (9) | 0.0032 (7) | 0.0056 (7) | 0.0004 (7) |
N2 | 0.0507 (10) | 0.0511 (10) | 0.0544 (11) | 0.0084 (8) | −0.0106 (8) | −0.0151 (8) |
O1 | 0.0578 (8) | 0.0440 (7) | 0.0478 (9) | 0.0042 (6) | 0.0004 (6) | −0.0084 (6) |
O2 | 0.0596 (9) | 0.0661 (10) | 0.0640 (11) | 0.0166 (7) | −0.0141 (8) | −0.0198 (8) |
S1 | 0.0455 (3) | 0.0623 (3) | 0.0537 (4) | 0.0105 (2) | −0.0047 (2) | −0.0168 (3) |
C1—C2 | 1.394 (3) | C10—H10 | 0.9300 |
C1—C6 | 1.398 (3) | C11—N2 | 1.367 (2) |
C1—S1 | 1.731 (2) | C11—C12 | 1.407 (3) |
C2—C3 | 1.374 (3) | C12—C13 | 1.370 (3) |
C2—H2 | 0.9300 | C12—H12 | 0.9300 |
C3—C4 | 1.392 (4) | C13—H13 | 0.9300 |
C3—H3 | 0.9300 | C14—N2 | 1.434 (2) |
C4—C5 | 1.367 (3) | C14—C15 | 1.507 (3) |
C4—H4 | 0.9300 | C14—H14A | 0.9700 |
C5—C6 | 1.397 (3) | C14—H14B | 0.9700 |
C5—H5 | 0.9300 | C15—O2 | 1.197 (2) |
C6—N1 | 1.385 (2) | C15—O1 | 1.318 (2) |
C7—N1 | 1.300 (2) | C16—O1 | 1.456 (2) |
C7—C8 | 1.460 (3) | C16—C17 | 1.488 (3) |
C7—S1 | 1.7579 (18) | C16—H16A | 0.9700 |
C8—C9 | 1.388 (3) | C16—H16B | 0.9700 |
C8—C13 | 1.397 (3) | C17—H17A | 0.9600 |
C9—C10 | 1.380 (3) | C17—H17B | 0.9600 |
C9—H9 | 0.9300 | C17—H17C | 0.9600 |
C10—C11 | 1.395 (3) | N2—H2A | 0.853 (9) |
C2—C1—C6 | 122.01 (19) | C13—C12—C11 | 120.77 (17) |
C2—C1—S1 | 128.85 (17) | C13—C12—H12 | 119.6 |
C6—C1—S1 | 109.13 (14) | C11—C12—H12 | 119.6 |
C3—C2—C1 | 117.9 (2) | C12—C13—C8 | 121.42 (17) |
C3—C2—H2 | 121.1 | C12—C13—H13 | 119.3 |
C1—C2—H2 | 121.1 | C8—C13—H13 | 119.3 |
C2—C3—C4 | 120.7 (2) | N2—C14—C15 | 109.62 (15) |
C2—C3—H3 | 119.6 | N2—C14—H14A | 109.7 |
C4—C3—H3 | 119.6 | C15—C14—H14A | 109.7 |
C5—C4—C3 | 121.4 (2) | N2—C14—H14B | 109.7 |
C5—C4—H4 | 119.3 | C15—C14—H14B | 109.7 |
C3—C4—H4 | 119.3 | H14A—C14—H14B | 108.2 |
C4—C5—C6 | 119.4 (2) | O2—C15—O1 | 124.76 (18) |
C4—C5—H5 | 120.3 | O2—C15—C14 | 124.23 (18) |
C6—C5—H5 | 120.3 | O1—C15—C14 | 111.01 (16) |
N1—C6—C5 | 125.91 (19) | O1—C16—C17 | 107.31 (17) |
N1—C6—C1 | 115.52 (16) | O1—C16—H16A | 110.3 |
C5—C6—C1 | 118.57 (19) | C17—C16—H16A | 110.3 |
N1—C7—C8 | 124.46 (16) | O1—C16—H16B | 110.3 |
N1—C7—S1 | 115.02 (14) | C17—C16—H16B | 110.3 |
C8—C7—S1 | 120.52 (13) | H16A—C16—H16B | 108.5 |
C9—C8—C13 | 117.59 (17) | C16—C17—H17A | 109.5 |
C9—C8—C7 | 122.20 (16) | C16—C17—H17B | 109.5 |
C13—C8—C7 | 120.21 (16) | H17A—C17—H17B | 109.5 |
C10—C9—C8 | 121.81 (17) | C16—C17—H17C | 109.5 |
C10—C9—H9 | 119.1 | H17A—C17—H17C | 109.5 |
C8—C9—H9 | 119.1 | H17B—C17—H17C | 109.5 |
C9—C10—C11 | 120.39 (17) | C7—N1—C6 | 110.97 (16) |
C9—C10—H10 | 119.8 | C11—N2—C14 | 123.52 (16) |
C11—C10—H10 | 119.8 | C11—N2—H2A | 121.2 (16) |
N2—C11—C10 | 122.80 (17) | C14—N2—H2A | 114.6 (16) |
N2—C11—C12 | 119.18 (16) | C15—O1—C16 | 116.58 (16) |
C10—C11—C12 | 118.00 (17) | C1—S1—C7 | 89.35 (9) |
C6—C1—C2—C3 | −1.2 (3) | C10—C11—C12—C13 | 1.5 (3) |
S1—C1—C2—C3 | 179.40 (17) | C11—C12—C13—C8 | −0.1 (3) |
C1—C2—C3—C4 | 0.8 (3) | C9—C8—C13—C12 | −1.0 (3) |
C2—C3—C4—C5 | −0.1 (4) | C7—C8—C13—C12 | 178.72 (17) |
C3—C4—C5—C6 | −0.3 (3) | N2—C14—C15—O2 | 0.6 (3) |
C4—C5—C6—N1 | 179.89 (19) | N2—C14—C15—O1 | −179.36 (16) |
C4—C5—C6—C1 | 0.0 (3) | C8—C7—N1—C6 | 180.00 (16) |
C2—C1—C6—N1 | −179.10 (18) | S1—C7—N1—C6 | −0.2 (2) |
S1—C1—C6—N1 | 0.4 (2) | C5—C6—N1—C7 | 179.97 (18) |
C2—C1—C6—C5 | 0.8 (3) | C1—C6—N1—C7 | −0.1 (2) |
S1—C1—C6—C5 | −179.68 (15) | C10—C11—N2—C14 | 8.1 (3) |
N1—C7—C8—C9 | 179.13 (18) | C12—C11—N2—C14 | −173.43 (19) |
S1—C7—C8—C9 | −0.6 (3) | C15—C14—N2—C11 | 177.26 (18) |
N1—C7—C8—C13 | −0.6 (3) | O2—C15—O1—C16 | 2.3 (3) |
S1—C7—C8—C13 | 179.68 (14) | C14—C15—O1—C16 | −177.66 (16) |
C13—C8—C9—C10 | 0.7 (3) | C17—C16—O1—C15 | 176.34 (17) |
C7—C8—C9—C10 | −178.98 (18) | C2—C1—S1—C7 | 179.0 (2) |
C8—C9—C10—C11 | 0.6 (3) | C6—C1—S1—C7 | −0.41 (15) |
C9—C10—C11—N2 | 176.82 (19) | N1—C7—S1—C1 | 0.39 (15) |
C9—C10—C11—C12 | −1.7 (3) | C8—C7—S1—C1 | −179.83 (16) |
N2—C11—C12—C13 | −177.13 (19) |
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O2i | 0.93 | 2.60 | 3.390 (2) | 144 |
N2—H2A···O2i | 0.85 (1) | 2.40 (1) | 3.188 (2) | 154 (2) |
Symmetry code: (i) −x−1, −y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C17H16N2O2S |
Mr | 312.38 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 298 |
a, b, c (Å) | 5.6303 (1), 26.1604 (5), 10.5989 (2) |
β (°) | 98.294 (1) |
V (Å3) | 1544.79 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.22 |
Crystal size (mm) | 0.36 × 0.24 × 0.21 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.926, 0.956 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11631, 3808, 3015 |
Rint | 0.076 |
(sin θ/λ)max (Å−1) | 0.668 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.058, 0.145, 1.07 |
No. of reflections | 3808 |
No. of parameters | 203 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.39, −0.30 |
Computer programs: SMART (Bruker, 2007), SAINT-Plus (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O2i | 0.93 | 2.60 | 3.390 (2) | 143.6 |
N2—H2A···O2i | 0.853 (9) | 2.402 (13) | 3.188 (2) | 154 (2) |
Symmetry code: (i) −x−1, −y, −z+1. |
References
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Thioflavin T (ThT) is a benzothiazole dye that exhibits enhanced fluorescence upon binding to amyloid fibrils and is commonly used to diagnose amyloid fibrils, both ex vivo and in vitro. Many derivatives of thioflavin T have been synthesized and evaluated recently (Kung et al., 2001; Qu et al., 2007; Zhang, et al., 2009). We are interested in developing fluorescent probes that are expected to bind to hydrophobic sites in proteins. With this in mind, the title compound, (I), was synthesized and we reported the crystal structure herein.
In the molecular structure (Fig. 1), the dihedral angle between the benzothiazole ring system and the benzene ring is 1.20 (2)°. The substituted amino substituent is in an extended conformation with an N—C—C—O torsion angle of 179.4 (3)°. In the crystal structure, pairs of molecules are connected by intermolecular N—H···O and weak C-H···O hydrogen bonds to form centrosymmetric dimers (Fig. 2).