Acta Cryst. (2009). E65, o2381 [ doi:10.1107/S1600536809035557 ]
The title chiral photochromic Schiff base compound, C16H17NO2, was synthesized from (R)-1-phenylethylamine and 5-methoxysalicylaldehyde. The molecule of the title compound exists in the phenol-imine tautomeric form. The dihedral angle between the two aromatic rings is 62.61 (11)°. An intramolecular O-H
N hydrogen bond with an ON distance of 2.589 (2) Å is observed. The crystal packing is stabilized by C-H![[pi]](/logos/entities/pi_rmgif.gif)
interactions involving the aromatic ring.
Treatment of equimolar R-1-phenylethylamine and 5-methoxysalicylaldehyde in methanol at 298 K overnight gave rise to a yellow-green compound (I). Prismatic crystals of (I) were grown from the resulting solution over a period of several days (yield 39.0%). Analysis found: C 73.98, H 6.49, N 5.37%; calculated for C16H17NO2: C 75.27, H 6.71, N, 5.49%. (precipitates containing non-stoichiometric cystalline water) m.p. 371 K. IR (Nujol, ν, cm-1): 1632 (imine band). UV-VIS (diffuse reflectance, nm): 255, 329, 470s h.
All H atoms were located in a difference map and refined freely [O-H = 0.98 (3) Å and C-H = 0.91 (3)-1.02 (3) Å]. Friedel pairs were merged.
Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
![[Figure 1]](./ci2897fig1thm.gif)
| Fig. 1. The molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. |
| C16H17NO2 | F(000) = 272 |
| Mr = 255.31 | Dx = 1.253 Mg m−3 |
| Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: P 2yb | Cell parameters from 1657 reflections |
| a = 8.270 (4) Å | θ = 2.5–27.5° |
| b = 5.886 (3) Å | µ = 0.08 mm−1 |
| c = 13.920 (7) Å | T = 100 K |
| β = 93.254 (7)° | Plate, yellow |
| V = 676.4 (6) Å3 | 0.21 × 0.19 × 0.07 mm |
| Z = 2 |
| Brruker SMART CCD area-detector diffractometer | 1677 independent reflections |
| Radiation source: fine-focus sealed tube | 1454 reflections with I > 2σ(I) |
| graphite | Rint = 0.074 |
| Detector resolution: 8.333 pixels mm-1 | θmax = 27.5°, θmin = 1.5° |
| φ and ω scans | h = −10→8 |
| Absorption correction: multi-scan (SADABS; Bruker, 1998) | k = −7→7 |
| Tmin = 0.983, Tmax = 0.994 | l = −17→16 |
| 3805 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)] = 0.042 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.088 | All H-atom parameters refined |
| S = 0.99 | w = 1/[σ2(Fo2) + (0.038P)2] where P = (Fo2 + 2Fc2)/3 |
| 1677 reflections | (Δ/σ)max = 0.001 |
| 240 parameters | Δρmax = 0.31 e Å−3 |
| 1 restraint | Δρmin = −0.18 e Å−3 |
| C16H17NO2 | V = 676.4 (6) Å3 |
| Mr = 255.31 | Z = 2 |
| Monoclinic, P21 | Mo Kα radiation |
| a = 8.270 (4) Å | µ = 0.08 mm−1 |
| b = 5.886 (3) Å | T = 100 K |
| c = 13.920 (7) Å | 0.21 × 0.19 × 0.07 mm |
| β = 93.254 (7)° |
| Brruker SMART CCD area-detector diffractometer | 1677 independent reflections |
| Absorption correction: multi-scan (SADABS; Bruker, 1998) | 1454 reflections with I > 2σ(I) |
| Tmin = 0.983, Tmax = 0.994 | Rint = 0.074 |
| 3805 measured reflections | θmax = 27.5° |
| R[F2 > 2σ(F2)] = 0.042 | All H-atom parameters refined |
| wR(F2) = 0.088 | Δρmax = 0.31 e Å−3 |
| S = 0.99 | Δρmin = −0.18 e Å−3 |
| 1677 reflections | Absolute structure: ? |
| 240 parameters | Flack parameter: ? |
| 1 restraint | Rogers parameter: ? |
Experimental. 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 > 2sigma(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. |
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. |
| x | y | z | Uiso*/Ueq | ||
| O1 | −0.10235 (18) | 0.3421 (3) | 0.24677 (11) | 0.0246 (4) | |
| O2 | −0.34502 (18) | 0.0560 (3) | −0.11019 (11) | 0.0236 (4) | |
| N1 | 0.0495 (2) | −0.0409 (3) | 0.26781 (13) | 0.0209 (4) | |
| C1 | −0.1599 (2) | 0.2610 (4) | 0.15989 (16) | 0.0204 (5) | |
| C2 | −0.2717 (3) | 0.3907 (4) | 0.10592 (17) | 0.0235 (5) | |
| C3 | −0.3316 (2) | 0.3147 (4) | 0.01743 (17) | 0.0214 (5) | |
| C4 | −0.2782 (2) | 0.1095 (4) | −0.02039 (15) | 0.0202 (5) | |
| C5 | −0.1684 (3) | −0.0231 (4) | 0.03255 (16) | 0.0200 (5) | |
| C6 | −0.1087 (2) | 0.0500 (4) | 0.12470 (15) | 0.0190 (5) | |
| C7 | 0.0002 (2) | −0.0964 (4) | 0.18197 (16) | 0.0198 (5) | |
| C8 | 0.1607 (3) | −0.1916 (4) | 0.32334 (16) | 0.0204 (5) | |
| C9 | 0.0764 (3) | −0.2731 (5) | 0.41192 (19) | 0.0253 (6) | |
| C10 | 0.3138 (2) | −0.0565 (4) | 0.34822 (15) | 0.0200 (5) | |
| C15 | 0.4606 (3) | −0.1240 (5) | 0.31292 (16) | 0.0237 (5) | |
| C14 | 0.5988 (3) | 0.0075 (5) | 0.32986 (17) | 0.0265 (6) | |
| C13 | 0.5917 (3) | 0.2063 (5) | 0.38184 (17) | 0.0269 (6) | |
| C12 | 0.4471 (3) | 0.2741 (5) | 0.41913 (16) | 0.0251 (5) | |
| C11 | 0.3098 (3) | 0.1428 (4) | 0.40203 (16) | 0.0224 (5) | |
| C16 | −0.3038 (3) | −0.1589 (5) | −0.14857 (18) | 0.0255 (6) | |
| H1 | −0.041 (3) | 0.216 (6) | 0.2758 (19) | 0.044 (9)* | |
| H2 | −0.307 (3) | 0.526 (5) | 0.1294 (16) | 0.020 (6)* | |
| H3 | −0.408 (3) | 0.398 (5) | −0.0179 (16) | 0.024 (6)* | |
| H5 | −0.129 (3) | −0.164 (4) | 0.0095 (14) | 0.013 (6)* | |
| H7 | 0.039 (3) | −0.236 (5) | 0.1538 (15) | 0.021 (6)* | |
| H8 | 0.186 (3) | −0.326 (5) | 0.2845 (16) | 0.022 (6)* | |
| H15 | 0.466 (3) | −0.261 (5) | 0.2753 (19) | 0.036 (8)* | |
| H14 | 0.701 (3) | −0.044 (5) | 0.3014 (16) | 0.030 (7)* | |
| H13 | 0.684 (3) | 0.319 (6) | 0.390 (2) | 0.046 (8)* | |
| H12 | 0.443 (3) | 0.421 (5) | 0.4568 (16) | 0.028 (7)* | |
| H11 | 0.210 (3) | 0.198 (5) | 0.4247 (16) | 0.029 (6)* | |
| H9A | 0.045 (3) | −0.149 (5) | 0.4484 (17) | 0.031 (7)* | |
| H16A | −0.330 (3) | −0.274 (5) | −0.1053 (18) | 0.031 (7)* | |
| H9B | −0.020 (3) | −0.371 (5) | 0.3935 (16) | 0.026 (6)* | |
| H16B | −0.191 (3) | −0.172 (4) | −0.1610 (14) | 0.014 (5)* | |
| H9C | 0.147 (3) | −0.381 (6) | 0.4531 (19) | 0.043 (8)* | |
| H16C | −0.365 (3) | −0.172 (5) | −0.2090 (18) | 0.027 (7)* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| O1 | 0.0236 (8) | 0.0249 (10) | 0.0252 (9) | −0.0010 (8) | 0.0002 (7) | −0.0063 (8) |
| O2 | 0.0230 (8) | 0.0276 (10) | 0.0198 (8) | 0.0002 (7) | −0.0012 (6) | 0.0021 (8) |
| N1 | 0.0171 (8) | 0.0238 (11) | 0.0218 (10) | −0.0012 (8) | 0.0011 (7) | −0.0013 (9) |
| C1 | 0.0191 (10) | 0.0217 (14) | 0.0208 (12) | −0.0029 (10) | 0.0046 (9) | −0.0015 (10) |
| C2 | 0.0208 (10) | 0.0195 (13) | 0.0306 (13) | 0.0001 (10) | 0.0055 (9) | −0.0011 (12) |
| C3 | 0.0144 (10) | 0.0230 (13) | 0.0268 (13) | 0.0015 (9) | 0.0023 (9) | 0.0066 (11) |
| C4 | 0.0174 (10) | 0.0251 (14) | 0.0184 (12) | −0.0031 (9) | 0.0035 (9) | 0.0022 (10) |
| C5 | 0.0173 (10) | 0.0210 (13) | 0.0219 (12) | −0.0021 (9) | 0.0033 (8) | −0.0003 (10) |
| C6 | 0.0160 (9) | 0.0203 (12) | 0.0209 (11) | −0.0021 (9) | 0.0031 (9) | 0.0001 (10) |
| C7 | 0.0155 (9) | 0.0230 (13) | 0.0212 (12) | −0.0017 (9) | 0.0043 (8) | 0.0002 (10) |
| C8 | 0.0202 (10) | 0.0194 (12) | 0.0215 (12) | 0.0014 (9) | 0.0002 (9) | −0.0014 (10) |
| C9 | 0.0233 (11) | 0.0265 (14) | 0.0263 (13) | −0.0046 (11) | 0.0019 (10) | 0.0000 (11) |
| C10 | 0.0219 (10) | 0.0228 (13) | 0.0149 (11) | −0.0009 (10) | −0.0015 (8) | 0.0034 (10) |
| C15 | 0.0234 (11) | 0.0286 (14) | 0.0193 (12) | 0.0033 (10) | 0.0024 (9) | 0.0005 (11) |
| C14 | 0.0213 (11) | 0.0342 (16) | 0.0242 (13) | 0.0011 (10) | 0.0042 (9) | 0.0044 (11) |
| C13 | 0.0258 (12) | 0.0322 (15) | 0.0224 (13) | −0.0081 (11) | −0.0012 (10) | 0.0043 (11) |
| C12 | 0.0302 (12) | 0.0255 (14) | 0.0192 (12) | −0.0041 (11) | −0.0014 (9) | 0.0002 (11) |
| C11 | 0.0219 (11) | 0.0233 (13) | 0.0219 (12) | 0.0021 (10) | 0.0011 (9) | 0.0000 (10) |
| C16 | 0.0269 (12) | 0.0280 (15) | 0.0217 (14) | 0.0011 (11) | 0.0011 (10) | −0.0009 (12) |
| O1—C1 | 1.361 (3) | C8—H8 | 0.99 (3) |
| O1—H1 | 0.98 (3) | C9—H9A | 0.93 (3) |
| O2—C4 | 1.374 (3) | C9—H9B | 1.00 (3) |
| O2—C16 | 1.422 (3) | C9—H9C | 1.02 (3) |
| N1—C7 | 1.283 (3) | C10—C15 | 1.393 (3) |
| N1—C8 | 1.466 (3) | C10—C11 | 1.393 (3) |
| C1—C2 | 1.387 (3) | C15—C14 | 1.390 (4) |
| C1—C6 | 1.409 (3) | C15—H15 | 0.96 (3) |
| C2—C3 | 1.376 (3) | C14—C13 | 1.379 (4) |
| C2—H2 | 0.91 (3) | C14—H14 | 1.00 (2) |
| C3—C4 | 1.399 (3) | C13—C12 | 1.389 (3) |
| C3—H3 | 0.92 (3) | C13—H13 | 1.01 (3) |
| C4—C5 | 1.379 (3) | C12—C11 | 1.383 (3) |
| C5—C6 | 1.415 (3) | C12—H12 | 1.01 (3) |
| C5—H5 | 0.95 (2) | C11—H11 | 0.95 (3) |
| C6—C7 | 1.452 (3) | C16—H16A | 0.94 (3) |
| C7—H7 | 0.97 (3) | C16—H16B | 0.96 (2) |
| C8—C10 | 1.519 (3) | C16—H16C | 0.96 (3) |
| C8—C9 | 1.528 (3) | ||
| C1—O1—H1 | 104.5 (17) | C8—C9—H9A | 110.3 (16) |
| C4—O2—C16 | 116.9 (2) | C8—C9—H9B | 111.4 (13) |
| C7—N1—C8 | 119.6 (2) | H9A—C9—H9B | 111 (2) |
| O1—C1—C2 | 118.5 (2) | C8—C9—H9C | 112.1 (14) |
| O1—C1—C6 | 121.4 (2) | H9A—C9—H9C | 110 (2) |
| C2—C1—C6 | 120.1 (2) | H9B—C9—H9C | 102 (2) |
| C3—C2—C1 | 120.0 (2) | C15—C10—C11 | 118.5 (2) |
| C3—C2—H2 | 119.8 (16) | C15—C10—C8 | 120.2 (2) |
| C1—C2—H2 | 120.2 (16) | C11—C10—C8 | 121.22 (19) |
| C2—C3—C4 | 120.8 (2) | C14—C15—C10 | 120.4 (2) |
| C2—C3—H3 | 120.4 (16) | C14—C15—H15 | 119.8 (16) |
| C4—C3—H3 | 118.8 (16) | C10—C15—H15 | 119.8 (16) |
| O2—C4—C5 | 125.1 (2) | C13—C14—C15 | 120.2 (2) |
| O2—C4—C3 | 114.9 (2) | C13—C14—H14 | 121.9 (17) |
| C5—C4—C3 | 120.0 (2) | C15—C14—H14 | 117.9 (17) |
| C4—C5—C6 | 119.9 (2) | C14—C13—C12 | 120.2 (2) |
| C4—C5—H5 | 122.7 (14) | C14—C13—H13 | 124.3 (17) |
| C6—C5—H5 | 117.4 (14) | C12—C13—H13 | 115.3 (18) |
| C1—C6—C5 | 119.1 (2) | C11—C12—C13 | 119.4 (2) |
| C1—C6—C7 | 121.4 (2) | C11—C12—H12 | 121.2 (14) |
| C5—C6—C7 | 119.4 (2) | C13—C12—H12 | 119.4 (14) |
| N1—C7—C6 | 121.0 (2) | C12—C11—C10 | 121.2 (2) |
| N1—C7—H7 | 119.8 (14) | C12—C11—H11 | 117.8 (17) |
| C6—C7—H7 | 119.2 (14) | C10—C11—H11 | 120.8 (17) |
| N1—C8—C10 | 107.1 (2) | O2—C16—H16A | 109.4 (17) |
| N1—C8—C9 | 108.32 (18) | O2—C16—H16B | 113.2 (14) |
| C10—C8—C9 | 113.1 (2) | H16A—C16—H16B | 109 (2) |
| N1—C8—H8 | 110.1 (14) | O2—C16—H16C | 106.1 (17) |
| C10—C8—H8 | 110.1 (14) | H16A—C16—H16C | 112 (2) |
| C9—C8—H8 | 108.1 (14) | H16B—C16—H16C | 107.6 (18) |
| O1—C1—C2—C3 | 179.53 (18) | C1—C6—C7—N1 | 2.0 (3) |
| C6—C1—C2—C3 | −0.6 (3) | C5—C6—C7—N1 | −176.18 (18) |
| C1—C2—C3—C4 | −1.6 (3) | C7—N1—C8—C10 | 120.2 (2) |
| C16—O2—C4—C5 | 3.7 (3) | C7—N1—C8—C9 | −117.5 (2) |
| C16—O2—C4—C3 | −175.42 (18) | N1—C8—C10—C15 | −116.8 (2) |
| C2—C3—C4—O2 | −178.62 (18) | C9—C8—C10—C15 | 124.0 (2) |
| C2—C3—C4—C5 | 2.2 (3) | N1—C8—C10—C11 | 59.8 (3) |
| O2—C4—C5—C6 | −179.69 (17) | C9—C8—C10—C11 | −59.5 (3) |
| C3—C4—C5—C6 | −0.6 (3) | C11—C10—C15—C14 | −1.1 (3) |
| O1—C1—C6—C5 | −177.98 (17) | C8—C10—C15—C14 | 175.5 (2) |
| C2—C1—C6—C5 | 2.2 (3) | C10—C15—C14—C13 | 0.0 (4) |
| O1—C1—C6—C7 | 3.8 (3) | C15—C14—C13—C12 | 1.2 (4) |
| C2—C1—C6—C7 | −176.03 (19) | C14—C13—C12—C11 | −1.3 (4) |
| C4—C5—C6—C1 | −1.5 (3) | C13—C12—C11—C10 | 0.1 (4) |
| C4—C5—C6—C7 | 176.70 (19) | C15—C10—C11—C12 | 1.1 (3) |
| C8—N1—C7—C6 | −179.40 (18) | C8—C10—C11—C12 | −175.5 (2) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O1—H1···N1 | 0.97 (3) | 1.72 (5) | 2.589 (2) | 151 (3) |
| C12—H12···Cg1i | 1.03 (4) | 2.72 (3) | 3.536 (3) | 137 (3) |
| C16—H16C···Cg1ii | 0.98 (4) | 2.71 (3) | 3.563 (3) | 149 (3) |
| Symmetry codes: (i) −x+1, y+1/2, −z+1; (ii) −x, y−1/2, −z. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O1—H1···N1 | 0.97 (3) | 1.72 (5) | 2.589 (2) | 151 (3) |
| C12—H12···Cg1i | 1.03 (4) | 2.72 (3) | 3.536 (3) | 137 (3) |
| C16—H16C···Cg1ii | 0.98 (4) | 2.71 (3) | 3.563 (3) | 149 (3) |
| Symmetry codes: (i) −x+1, y+1/2, −z+1; (ii) −x, y−1/2, −z. |
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Because of structural flexibility and their application for switching materials and so on, Schiff base compounds are one of the most extensively used ligands in the field of coordination chemistry (Yamada, 1999). Especially, aiming at multifunctional chiral materials, we have investigated Schiff base CuII, NiII, or ZnII complexes in view of thermally induced structural phase transition in the solid state (Akitsu & Einaga, 2004), structural change by occlusion of solvents (Akitsu & Einaga, 2005a), chiral conformational change in a solution induced by a photochromic solute (Akitsu & Einaga, 2005b,2006a; Akitsu, 2007), and novel induced CD to achiral metallodendrimers (Akitsu et al., 2009). On the other hand, free Schiff base ligands (Akitsu et al., 2004, Akitsu & Einaga, 2006b) have been also studied as multifunctional components, for example photochromic and thermochromic or fluorescence materials (Hadjoudis et al., 2004) and nonlinear optical materials (Sliwa et al., 2005) and so on. In order to clarify the role of electron-donating methoxy group, as free ligands for tautomerism and photochromism (Hadjoudis et al., 1987), crystal structure of the title compound, (I), has been determined.
Crystal structure of (I) is similar to those of the analogous derivatives (Santoni & Rehder, 2004; Akitsu & Einaga, 2006b). Molecule of (I) (Fig. 1) adopts an E configuration with respect to the imine C═N double bond with a C6—C7—N1—C8 torsion angle of -179.40 (18)°. Thus, the π-conjugate system around the imine group is essentially planar. The C1—O1 bond distance of 1.361 (3) Å suggests that it is in the phenol-imine tautomer. The contraction of the C7═N1 bond [1.283 (3) Å] is also in agreement with the phenol-imine tautomer. As for the methoxy group, the O2—C4 and O2—C16 bond distaces are 1.374 (3) and 1.422 (3) Å, respectively, and the C4—O2—C16 bond angle is 116.9 (2)°. Beside them, geometric parameters reported here agree with corresponding values reported for analogous Schiff base compounds containing the 1-phenylethylamine group (Antonov et al., 1995; Liu et al., 1997). The planarity of (I) is stabilized by an intramolecular O—H···N hydrogen bond (Table 1). However, there is no intermolecular hydrogen bonds associated with the methoxy group. The crystal packing is stabilized by C—H···π interactions involving the C10-C15 ring.