Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104004500/fr1468sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104004500/fr1468Isup2.hkl |
CCDC reference: 237949
Enoxacin was a gift from Rhone-Poulenc Rohrer Pakistan (Pvt) LTD, Wah Cant., Pakistan. It was recrystallized from dimethylformamide, affording colourless needles of (I) [m.p. 497–498 K (decomposes)].
The H atoms were located from a difference Fourier synthesis and were allowed to refine with isotropic displacement parameters. The final difference map was free of any chemically significant features.
Data collection: COLLECT (Nonius, 1998); cell refinement: HKL DENZO (Otwinowski & Minor, 1997); data reduction: SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.
Fig. 1. A drawing of the zwitterion of (I), with displacement ellipsoids plotted at the 50% probability level. | |
Fig. 2. A drawing of the unit cell of (I), showing the hydrogen bonding (dashed lines). |
C15H17FN4O3·3H2O | F(000) = 792 |
Mr = 374.37 | Dx = 1.439 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 7267 reflections |
a = 13.618 (3) Å | θ = 3.1–27.5° |
b = 7.2963 (13) Å | µ = 0.12 mm−1 |
c = 18.316 (5) Å | T = 173 K |
β = 108.282 (12)° | Needle, colourless |
V = 1728.0 (7) Å3 | 0.32 × 0.06 × 0.05 mm |
Z = 4 |
Nonius KappaCCD area-detector diffractometer | 3945 independent reflections |
Radiation source: fine-focus sealed tube | 3146 reflections with I > 2.0σ(I) |
Graphite monochromator | Rint = 0.023 |
ω and ϕ scans | θmax = 27.5°, θmin = 3.1° |
Absorption correction: multi-scan (SORTAV; Blessing, 1997) | h = −17→17 |
Tmin = 0.95, Tmax = 0.99 | k = −8→9 |
7267 measured reflections | l = −23→23 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.036 | All H-atom parameters refined |
wR(F2) = 0.097 | w = 1/[σ2(Fo2) + (0.0458P)2 + 0.3941P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max = 0.001 |
3945 reflections | Δρmax = 0.27 e Å−3 |
328 parameters | Δρmin = −0.21 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.011 (2) |
C15H17FN4O3·3H2O | V = 1728.0 (7) Å3 |
Mr = 374.37 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.618 (3) Å | µ = 0.12 mm−1 |
b = 7.2963 (13) Å | T = 173 K |
c = 18.316 (5) Å | 0.32 × 0.06 × 0.05 mm |
β = 108.282 (12)° |
Nonius KappaCCD area-detector diffractometer | 3945 independent reflections |
Absorption correction: multi-scan (SORTAV; Blessing, 1997) | 3146 reflections with I > 2.0σ(I) |
Tmin = 0.95, Tmax = 0.99 | Rint = 0.023 |
7267 measured reflections |
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.097 | All H-atom parameters refined |
S = 1.04 | Δρmax = 0.27 e Å−3 |
3945 reflections | Δρmin = −0.21 e Å−3 |
328 parameters |
x | y | z | Uiso*/Ueq | ||
F1 | 0.29770 (6) | 0.27964 (12) | 0.53436 (4) | 0.0289 (2) | |
O1 | 0.67934 (7) | 0.19112 (14) | 0.66058 (5) | 0.0257 (2) | |
O2 | 0.91105 (7) | 0.03255 (13) | 0.56589 (5) | 0.0258 (2) | |
O5 | 1.06737 (9) | 0.22321 (15) | 0.53753 (7) | 0.0332 (3) | |
H051 | 1.0188 (18) | 0.155 (3) | 0.5526 (13) | 0.064 (6)* | |
H052 | 1.0873 (18) | 0.152 (3) | 0.5065 (14) | 0.065 (7)* | |
O6 | 0.89926 (10) | 0.40362 (17) | 0.42202 (7) | 0.0435 (3) | |
H061 | 0.9024 (17) | 0.521 (4) | 0.4338 (13) | 0.066 (7)* | |
H062 | 0.953 (2) | 0.345 (4) | 0.4603 (15) | 0.083 (8)* | |
O3 | 0.89070 (7) | 0.18629 (14) | 0.66493 (5) | 0.0268 (2) | |
N1 | 0.62254 (8) | 0.18047 (14) | 0.42644 (6) | 0.0184 (2) | |
N2 | 0.44810 (8) | 0.23710 (14) | 0.40407 (6) | 0.0180 (2) | |
N3 | 0.27088 (8) | 0.27278 (14) | 0.37190 (6) | 0.0190 (2) | |
N4 | 0.08989 (9) | 0.36270 (16) | 0.24593 (7) | 0.0234 (3) | |
H41 | 0.1121 (14) | 0.479 (3) | 0.2330 (10) | 0.042 (5)* | |
H42 | 0.0214 (16) | 0.336 (3) | 0.2116 (11) | 0.045 (5)* | |
O4 | 0.17460 (8) | 0.67580 (13) | 0.20501 (6) | 0.0266 (2) | |
H041 | 0.1484 (17) | 0.758 (3) | 0.1656 (13) | 0.054 (6)* | |
H042 | 0.2061 (18) | 0.736 (3) | 0.2489 (13) | 0.057 (6)* | |
C1 | 0.71860 (10) | 0.15107 (17) | 0.47545 (7) | 0.0183 (3) | |
C2 | 0.74411 (9) | 0.15115 (16) | 0.55405 (7) | 0.0174 (3) | |
C3 | 0.66554 (9) | 0.18642 (16) | 0.59000 (7) | 0.0178 (3) | |
C4 | 0.56202 (9) | 0.21544 (16) | 0.53554 (7) | 0.0172 (2) | |
C5 | 0.47566 (10) | 0.24360 (17) | 0.56079 (7) | 0.0192 (3) | |
C6 | 0.38046 (10) | 0.26461 (17) | 0.50840 (7) | 0.0197 (3) | |
C7 | 0.36631 (9) | 0.26157 (16) | 0.42782 (7) | 0.0174 (3) | |
C8 | 0.54200 (9) | 0.21219 (15) | 0.45582 (7) | 0.0166 (2) | |
C9 | 0.60532 (11) | 0.18860 (19) | 0.34258 (7) | 0.0231 (3) | |
C10 | 0.60074 (14) | 0.3837 (2) | 0.31392 (9) | 0.0346 (4) | |
C11 | 0.85649 (9) | 0.11979 (17) | 0.59828 (7) | 0.0189 (3) | |
C12 | 0.19312 (10) | 0.40322 (18) | 0.38136 (8) | 0.0230 (3) | |
C13 | 0.08697 (10) | 0.3612 (2) | 0.32636 (8) | 0.0241 (3) | |
C14 | 0.16531 (11) | 0.2232 (2) | 0.23734 (8) | 0.0266 (3) | |
C15 | 0.27263 (10) | 0.26361 (19) | 0.29235 (8) | 0.0237 (3) | |
H1 | 0.7706 (12) | 0.133 (2) | 0.4508 (8) | 0.020 (4)* | |
H5 | 0.4829 (13) | 0.246 (2) | 0.6137 (10) | 0.029 (4)* | |
H9A | 0.6615 (12) | 0.119 (2) | 0.3338 (8) | 0.023 (4)* | |
H9B | 0.5389 (14) | 0.121 (2) | 0.3164 (10) | 0.035 (4)* | |
H10A | 0.6620 (16) | 0.451 (3) | 0.3421 (11) | 0.052 (6)* | |
H10B | 0.5983 (14) | 0.383 (3) | 0.2597 (12) | 0.049 (5)* | |
H10C | 0.5383 (15) | 0.449 (3) | 0.3179 (10) | 0.045 (5)* | |
H12A | 0.1904 (13) | 0.399 (2) | 0.4336 (10) | 0.033 (4)* | |
H12B | 0.2137 (11) | 0.531 (2) | 0.3700 (8) | 0.024 (4)* | |
H13A | 0.0643 (13) | 0.241 (2) | 0.3359 (9) | 0.028 (4)* | |
H13B | 0.0369 (12) | 0.457 (2) | 0.3308 (9) | 0.030 (4)* | |
H14A | 0.1411 (13) | 0.098 (2) | 0.2476 (9) | 0.032 (4)* | |
H14B | 0.1658 (13) | 0.228 (2) | 0.1862 (10) | 0.026 (4)* | |
H15A | 0.3195 (12) | 0.164 (2) | 0.2887 (9) | 0.024 (4)* | |
H15B | 0.2999 (12) | 0.380 (2) | 0.2794 (9) | 0.026 (4)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F1 | 0.0160 (4) | 0.0485 (5) | 0.0229 (4) | 0.0049 (3) | 0.0072 (3) | −0.0009 (3) |
O1 | 0.0180 (5) | 0.0418 (6) | 0.0149 (4) | −0.0010 (4) | 0.0018 (4) | 0.0002 (4) |
O2 | 0.0177 (5) | 0.0321 (5) | 0.0266 (5) | 0.0041 (4) | 0.0056 (4) | −0.0033 (4) |
O5 | 0.0354 (6) | 0.0288 (5) | 0.0396 (6) | −0.0055 (4) | 0.0176 (5) | −0.0084 (4) |
O6 | 0.0525 (8) | 0.0321 (6) | 0.0329 (6) | −0.0033 (5) | −0.0055 (5) | −0.0062 (5) |
O3 | 0.0159 (5) | 0.0368 (6) | 0.0220 (5) | 0.0045 (4) | −0.0022 (4) | −0.0063 (4) |
N1 | 0.0146 (5) | 0.0249 (5) | 0.0146 (5) | 0.0002 (4) | 0.0029 (4) | −0.0002 (4) |
N2 | 0.0140 (5) | 0.0206 (5) | 0.0171 (5) | 0.0006 (4) | 0.0016 (4) | 0.0003 (4) |
N3 | 0.0136 (5) | 0.0231 (5) | 0.0171 (5) | 0.0035 (4) | 0.0000 (4) | −0.0012 (4) |
N4 | 0.0146 (5) | 0.0250 (6) | 0.0249 (6) | −0.0019 (4) | −0.0021 (4) | 0.0043 (4) |
O4 | 0.0291 (6) | 0.0269 (5) | 0.0210 (5) | −0.0038 (4) | 0.0040 (4) | 0.0005 (4) |
C1 | 0.0132 (6) | 0.0210 (6) | 0.0197 (6) | −0.0001 (4) | 0.0036 (5) | −0.0003 (4) |
C2 | 0.0132 (6) | 0.0194 (6) | 0.0171 (6) | −0.0001 (4) | 0.0011 (5) | 0.0001 (4) |
C3 | 0.0157 (6) | 0.0189 (6) | 0.0167 (6) | −0.0012 (4) | 0.0018 (5) | −0.0001 (4) |
C4 | 0.0149 (6) | 0.0182 (6) | 0.0164 (6) | −0.0008 (4) | 0.0020 (5) | −0.0004 (4) |
C5 | 0.0186 (6) | 0.0229 (6) | 0.0155 (6) | −0.0002 (5) | 0.0042 (5) | −0.0013 (4) |
C6 | 0.0151 (6) | 0.0242 (6) | 0.0206 (6) | 0.0010 (5) | 0.0065 (5) | −0.0017 (5) |
C7 | 0.0149 (6) | 0.0163 (6) | 0.0187 (6) | 0.0000 (4) | 0.0018 (5) | −0.0009 (4) |
C8 | 0.0140 (6) | 0.0175 (6) | 0.0166 (6) | 0.0001 (4) | 0.0024 (5) | −0.0002 (4) |
C9 | 0.0195 (7) | 0.0341 (7) | 0.0145 (6) | 0.0019 (5) | 0.0035 (5) | −0.0025 (5) |
C10 | 0.0424 (10) | 0.0414 (9) | 0.0226 (7) | 0.0074 (7) | 0.0139 (7) | 0.0078 (6) |
C11 | 0.0153 (6) | 0.0185 (6) | 0.0212 (6) | 0.0005 (4) | 0.0034 (5) | 0.0023 (4) |
C12 | 0.0158 (6) | 0.0254 (7) | 0.0244 (7) | 0.0054 (5) | 0.0016 (5) | −0.0024 (5) |
C13 | 0.0141 (6) | 0.0284 (7) | 0.0267 (7) | 0.0014 (5) | 0.0018 (5) | 0.0038 (5) |
C14 | 0.0216 (7) | 0.0308 (7) | 0.0216 (7) | 0.0014 (5) | −0.0017 (5) | −0.0025 (5) |
C15 | 0.0176 (6) | 0.0314 (7) | 0.0186 (6) | 0.0033 (5) | 0.0006 (5) | −0.0002 (5) |
F1—C6 | 1.3581 (15) | C2—C3 | 1.445 (2) |
O1—C3 | 1.2471 (16) | C2—C11 | 1.508 (2) |
O2—C11 | 1.2593 (16) | C3—C4 | 1.465 (2) |
O5—H051 | 0.94 (2) | C4—C8 | 1.399 (2) |
O5—H052 | 0.87 (3) | C4—C5 | 1.407 (2) |
O6—H061 | 0.88 (3) | C5—C6 | 1.358 (2) |
O6—H062 | 0.94 (3) | C5—H5 | 0.94 (2) |
O3—C11 | 1.259 (2) | C6—C7 | 1.428 (2) |
N1—C1 | 1.351 (2) | C9—C10 | 1.512 (2) |
N1—C8 | 1.384 (2) | C9—H9A | 0.97 (2) |
N1—C9 | 1.481 (2) | C9—H9B | 1.01 (2) |
N2—C7 | 1.329 (2) | C10—H10A | 0.97 (2) |
N2—C8 | 1.344 (2) | C10—H10B | 0.98 (2) |
N3—C7 | 1.382 (2) | C10—H10C | 1.00 (2) |
N3—C15 | 1.466 (2) | C12—C13 | 1.512 (2) |
N3—C12 | 1.474 (2) | C12—H12A | 0.97 (2) |
N4—C13 | 1.486 (2) | C12—H12B | 1.02 (2) |
N4—C14 | 1.489 (2) | C13—H13A | 0.96 (2) |
N4—H41 | 0.96 (2) | C13—H13B | 1.00 (2) |
N4—H42 | 0.97 (2) | C14—C15 | 1.521 (2) |
O4—H041 | 0.92 (2) | C14—H14A | 1.01 (2) |
O4—H042 | 0.90 (2) | C14—H14B | 0.94 (2) |
C1—C2 | 1.371 (2) | C15—H15A | 0.98 (2) |
C1—H1 | 0.96 (2) | C15—H15B | 0.99 (2) |
H051—O5—H052 | 105 (2) | N1—C9—C10 | 111.96 (11) |
H061—O6—H062 | 107 (2) | N1—C9—H9A | 105.9 (9) |
C1—N1—C8 | 119.23 (10) | C10—C9—H9A | 112.7 (9) |
C1—N1—C9 | 120.05 (11) | N1—C9—H9B | 107.4 (10) |
C8—N1—C9 | 120.64 (10) | C10—C9—H9B | 111.3 (10) |
C7—N2—C8 | 119.81 (11) | H9A—C9—H9B | 107.3 (13) |
C7—N3—C15 | 115.41 (10) | C9—C10—H10A | 111.0 (12) |
C7—N3—C12 | 119.64 (10) | C9—C10—H10B | 109.3 (12) |
C15—N3—C12 | 112.49 (10) | H10A—C10—H10B | 107.0 (16) |
C13—N4—C14 | 109.48 (10) | C9—C10—H10C | 111.7 (11) |
C13—N4—H41 | 111.2 (11) | H10A—C10—H10C | 109.3 (17) |
C14—N4—H41 | 107.4 (11) | H10B—C10—H10C | 108.4 (15) |
C13—N4—H42 | 108.9 (11) | O3—C11—O2 | 123.91 (11) |
C14—N4—H42 | 110.4 (11) | O3—C11—C2 | 117.84 (11) |
H41—N4—H42 | 109.5 (15) | O2—C11—C2 | 118.23 (11) |
H041—O4—H042 | 109.8 (19) | N3—C12—C13 | 111.27 (11) |
N1—C1—C2 | 124.82 (12) | N3—C12—H12A | 110.2 (10) |
N1—C1—H1 | 114.3 (9) | C13—C12—H12A | 109.1 (10) |
C2—C1—H1 | 120.8 (9) | N3—C12—H12B | 108.4 (8) |
C1—C2—C3 | 119.92 (11) | C13—C12—H12B | 108.6 (8) |
C1—C2—C11 | 116.38 (11) | H12A—C12—H12B | 109.4 (13) |
C3—C2—C11 | 123.66 (11) | N4—C13—C12 | 109.99 (11) |
O1—C3—C2 | 125.81 (11) | N4—C13—H13A | 107.3 (10) |
O1—C3—C4 | 120.12 (11) | C12—C13—H13A | 110.9 (10) |
C2—C3—C4 | 114.06 (11) | N4—C13—H13B | 107.9 (9) |
C8—C4—C5 | 115.85 (11) | C12—C13—H13B | 109.8 (9) |
C8—C4—C3 | 122.64 (11) | H13A—C13—H13B | 110.7 (14) |
C5—C4—C3 | 121.49 (11) | N4—C14—C15 | 110.40 (11) |
C6—C5—C4 | 119.69 (12) | N4—C14—H14A | 108.9 (9) |
C6—C5—H5 | 119.6 (10) | C15—C14—H14A | 110.8 (9) |
C4—C5—H5 | 120.7 (10) | N4—C14—H14B | 107.7 (10) |
C5—C6—F1 | 118.36 (11) | C15—C14—H14B | 110.3 (10) |
C5—C6—C7 | 121.20 (12) | H14A—C14—H14B | 108.7 (13) |
F1—C6—C7 | 120.37 (11) | N3—C15—C14 | 110.81 (12) |
N2—C7—N3 | 117.09 (11) | N3—C15—H15A | 108.3 (9) |
N2—C7—C6 | 119.04 (11) | C14—C15—H15A | 108.8 (9) |
N3—C7—C6 | 123.77 (11) | N3—C15—H15B | 108.9 (9) |
N2—C8—N1 | 116.30 (11) | C14—C15—H15B | 111.3 (9) |
N2—C8—C4 | 124.38 (11) | H15A—C15—H15B | 108.6 (13) |
N1—C8—C4 | 119.32 (11) | ||
C8—N1—C1—C2 | −0.47 (18) | F1—C6—C7—N3 | −0.17 (18) |
C9—N1—C1—C2 | 176.19 (11) | C7—N2—C8—N1 | 177.54 (10) |
N1—C1—C2—C3 | −0.68 (19) | C7—N2—C8—C4 | −2.07 (18) |
N1—C1—C2—C11 | −178.60 (11) | C1—N1—C8—N2 | −178.83 (10) |
C1—C2—C3—O1 | −179.57 (12) | C9—N1—C8—N2 | 4.53 (16) |
C11—C2—C3—O1 | −1.81 (19) | C1—N1—C8—C4 | 0.81 (17) |
C1—C2—C3—C4 | 1.36 (16) | C9—N1—C8—C4 | −175.84 (11) |
C11—C2—C3—C4 | 179.12 (11) | C5—C4—C8—N2 | 1.25 (17) |
O1—C3—C4—C8 | 179.83 (11) | C3—C4—C8—N2 | 179.59 (11) |
C2—C3—C4—C8 | −1.04 (16) | C5—C4—C8—N1 | −178.36 (11) |
O1—C3—C4—C5 | −1.92 (18) | C3—C4—C8—N1 | −0.02 (17) |
C2—C3—C4—C5 | 177.21 (11) | C1—N1—C9—C10 | −98.51 (14) |
C8—C4—C5—C6 | 0.30 (17) | C8—N1—C9—C10 | 78.11 (15) |
C3—C4—C5—C6 | −178.06 (11) | C1—C2—C11—O3 | 152.93 (12) |
C4—C5—C6—F1 | 175.79 (11) | C3—C2—C11—O3 | −24.90 (18) |
C4—C5—C6—C7 | −0.99 (19) | C1—C2—C11—O2 | −25.47 (17) |
C8—N2—C7—N3 | −175.30 (10) | C3—C2—C11—O2 | 156.70 (12) |
C8—N2—C7—C6 | 1.27 (17) | C7—N3—C12—C13 | −165.17 (11) |
C15—N3—C7—N2 | −2.43 (15) | C15—N3—C12—C13 | 54.49 (15) |
C12—N3—C7—N2 | −141.67 (12) | C14—N4—C13—C12 | 59.33 (14) |
C15—N3—C7—C6 | −178.83 (11) | N3—C12—C13—N4 | −56.81 (15) |
C12—N3—C7—C6 | 41.93 (17) | C13—N4—C14—C15 | −59.20 (15) |
C5—C6—C7—N2 | 0.21 (18) | C7—N3—C15—C14 | 164.02 (11) |
F1—C6—C7—N2 | −176.50 (11) | C12—N3—C15—C14 | −53.87 (14) |
C5—C6—C7—N3 | 176.55 (11) | N4—C14—C15—N3 | 56.25 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
O5—H051···O2 | 0.94 (2) | 1.80 (3) | 2.726 (2) | 170 (2) |
O5—H052···O2i | 0.87 (3) | 1.89 (3) | 2.740 (2) | 162 (2) |
O6—H061···O5ii | 0.88 (3) | 1.95 (3) | 2.821 (2) | 171 (2) |
O6—H062···O5 | 0.94 (3) | 1.96 (3) | 2.900 (2) | 178 (2) |
N4—H41···O4 | 0.96 (2) | 1.82 (2) | 2.767 (2) | 169 (2) |
N4—H42···O3iii | 0.97 (2) | 1.72 (2) | 2.676 (2) | 168 (2) |
O4—H041···O6iv | 0.92 (2) | 1.86 (2) | 2.779 (2) | 173 (2) |
O4—H042···O1v | 0.90 (2) | 1.96 (2) | 2.809 (2) | 157 (2) |
Symmetry codes: (i) −x+2, −y, −z+1; (ii) −x+2, −y+1, −z+1; (iii) x−1, −y+1/2, z−1/2; (iv) −x+1, y+1/2, −z+1/2; (v) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C15H17FN4O3·3H2O |
Mr | 374.37 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 173 |
a, b, c (Å) | 13.618 (3), 7.2963 (13), 18.316 (5) |
β (°) | 108.282 (12) |
V (Å3) | 1728.0 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.32 × 0.06 × 0.05 |
Data collection | |
Diffractometer | Nonius KappaCCD area-detector diffractometer |
Absorption correction | Multi-scan (SORTAV; Blessing, 1997) |
Tmin, Tmax | 0.95, 0.99 |
No. of measured, independent and observed [I > 2.0σ(I)] reflections | 7267, 3945, 3146 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.097, 1.04 |
No. of reflections | 3945 |
No. of parameters | 328 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.27, −0.21 |
Computer programs: COLLECT (Nonius, 1998), HKL DENZO (Otwinowski & Minor, 1997), SCALEPACK (Otwinowski & Minor, 1997), SAPI91 (Fan, 1991), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976), SHELXL97.
F1—C6 | 1.3581 (15) | N2—C7 | 1.329 (2) |
O1—C3 | 1.2471 (16) | N2—C8 | 1.344 (2) |
O2—C11 | 1.2593 (16) | N3—C7 | 1.382 (2) |
O3—C11 | 1.259 (2) | N3—C15 | 1.466 (2) |
N1—C1 | 1.351 (2) | N3—C12 | 1.474 (2) |
N1—C8 | 1.384 (2) | N4—C13 | 1.486 (2) |
N1—C9 | 1.481 (2) | N4—C14 | 1.489 (2) |
C1—N1—C8 | 119.23 (10) | C7—N3—C15 | 115.41 (10) |
C1—N1—C9 | 120.05 (11) | C7—N3—C12 | 119.64 (10) |
C8—N1—C9 | 120.64 (10) | C15—N3—C12 | 112.49 (10) |
C7—N2—C8 | 119.81 (11) | C13—N4—C14 | 109.48 (10) |
D—H···A | D—H | H···A | D···A | D—H···A |
O5—H051···O2 | 0.94 (2) | 1.80 (3) | 2.726 (2) | 170 (2) |
O5—H052···O2i | 0.87 (3) | 1.89 (3) | 2.740 (2) | 162 (2) |
O6—H061···O5ii | 0.88 (3) | 1.95 (3) | 2.821 (2) | 171 (2) |
O6—H062···O5 | 0.94 (3) | 1.96 (3) | 2.900 (2) | 178 (2) |
N4—H41···O4 | 0.96 (2) | 1.82 (2) | 2.767 (2) | 169 (2) |
N4—H42···O3iii | 0.97 (2) | 1.72 (2) | 2.676 (2) | 168 (2) |
O4—H041···O6iv | 0.92 (2) | 1.86 (2) | 2.779 (2) | 173 (2) |
O4—H042···O1v | 0.90 (2) | 1.96 (2) | 2.809 (2) | 157 (2) |
Symmetry codes: (i) −x+2, −y, −z+1; (ii) −x+2, −y+1, −z+1; (iii) x−1, −y+1/2, z−1/2; (iv) −x+1, y+1/2, −z+1/2; (v) −x+1, −y+1, −z+1. |
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Enoxacin belongs to the second generation fluoroquinolone antimicrobial agents (Smith, 2000). Its structure-activity relationship (Koga et al., 1980; Domagala et al., 1986; Domagala, 1994; Gootz & Brighty, 1996) and pharmacokinetics (Wise et al., 1986) have been extensively studied. Like other quinolone antimicrobials, it exerts its action by inhibiting enzyme DNA-gyrase, which is responsible for the continuous introduction of negative supercoils into DNA (Alfred et al., 1996; Gootz et al., 1994). Enoxacin, the naphthyridone analogue of norfloxacin, possesses roughly similar antibacterial activity but improved bioavailability over the latter (Gaja, 1992; Child et al., 1995). There are a number of reported drug interactions of enoxacin with milk, food, antacids and H2-receptor antagonists. Drug interactions have been reported when enoxacin is co-administered with magnesium and aluminium hydroxide, resulting in decreased levels of enoxacin in plasma and urine (Jaehde et al., 1994). There is additional evidence of the formation of complexes with Mg and Ca cations at pH 7.4, the binding sites being first the carbonyl and carboxyl groups, then the N4 piperazinyl atom (Lecomte & Chenon, 1996). In this paper, we report the structure of enoxacin trihydrate, (I). \sch
The structure of (I) is composed of a zwitterionic molecule of enoxacin (Fig. 1) and three molecules of water of solvation in an asymmetric unit, forming a strong network of hydrogen bonds (Fig. 2). The zwitterion is composed of an essentially planar naphthyridine ring system [maximum deviation for C6 0.0269 (10) Å], which is substituted with ethyl, fluoro, oxo, carboxyl and piperazinium groups. The carboxylate group lies out of the plane of the naphthyridine ring system, with an angle 26.13 (6)° between the mean planes formed by the two entities. The ethyl group attached to N1 is oriented approximately at a right angle to the plane of the naphthyridine ring [80.80 (11)°]. The piperazinium ring adopts a chair conformation, with puckering parameters (Cremer & Pople, 1975) Q = 0.571 (1) Å, θ = 175.4 (1)° and ϕ = 357 (2)°.
The zwitterions are stacked in the form of sheets lying parallel to each other and are hydrogen-bonded via a piperazinium ammonium H atom and a carboxylate moiety in a head-to-tail manner. The crystal structure of (I) is further strengthened by the involvement of the other ammonium H atom in a hydrogen bond with a hydration water molecule, which is also hydrogen-bonded to another zwitterion through its carbonyl function. As a matter of fact, the O and H atoms of all water molecules are involved in strong hydrogen bonding; details of the hydrogen bonding are given in Table 2.
A search of the Cambridge Structural Database (Version 1.6, 2003 release; Allen, 2002) yielded only one entry containing the piperazinyl-oxo-naphthyridine-carboxylate moiety, namely nalidixic acid (Datta et al., 1995), while there are 32 structures in the database containing the quinoline ring system instead of the naphthyridine ring system.