organic compounds
Z)-2-phenylhydrazin-1-ylidene]naphthalen-2(1H)-one
of 1-[(aUnité de recherche de Chimie de l'Environnement et Moléculaire Structurale, Faculté du Sciences Exactes, Université de Constantine 1, 25000 Constantine, Algeria
*Correspondence e-mail: king.ali@hotmail.fr
In the title compound, C16H12N2O, the dihedral angle between the planes of the benzene ring and naphthalenone ring system is 1.89 (8)°; an intramolecular N—H⋯O hydrogen bond occurs between the imino group and the carbonyl group. In the crystal, molecules are linked by weak C—H⋯π interactions into supramolecular chains propagating along the [01-1] direction.
Keywords: crystal structure; hydrazone; naphthalenone; hydrogen bonding; C—H⋯π interactions.
CCDC reference: 1057924
1. Related literature
For general background to et al. (2004); Oueslati et al. (2004).
and their use in dyes, pigments and advanced materials, see: Lee2. Experimental
2.1. Crystal data
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2.2. Data collection
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2.3. Refinement
|
Data collection: APEX2 (Bruker, 2006); cell SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for publication: PLATON.
Supporting information
CCDC reference: 1057924
https://doi.org/10.1107/S2056989015006775/xu5845sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989015006775/xu5845Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989015006775/xu5845Isup3.cml
Treatment of aniline (0.02 mol) in 6 ml of 12M HCl and NaNO2 (0.0214 mol) in 8 ml of H2O for 30 min. To the obtained solution, was added dropwise a solution of naphthalen-2-ol, and the resulting brown precipitates were filtrated and washed with water, and dried in a desiccator for several days. Single crystals were obtained by slow evaporation from a pentane solution.
The imino-H atom was located in a difference Fourier map and refined freely with Uiso(H) = 1.2Ueq(N). Other H atoms were placed in geometrically idealized positions and refined as riding, with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C).
The azo dyes are by far the most important class, accounting for over 50% of all commercial dyes, and having been studied more than other class (Lee et al., 2004; Oueslati et al., 2004). Azo dyes contain at least one azo group (–N=N–) but can contain two (diazo), three(triazo), or, more rarely, four (tetrakisazo) or more (polyazo) azo groups. The azo group is attached to two groups, of which at least one, but more usually both are aromatic. They exist in the Trans form in which the band angle is 120°, the nitrogen atoms are sp2 hybridized. Almost without exception, azo dyes are made by diazotization of primary aromatic amine followed by coupling of the resultant diazonium salt with an electron-richnucleophile. We report here in the
of the title compound, obtained through the diazotization of aniline followed by a coupling reaction with2-naphthol.The molecular structure of (I) and the atom-numbering scheme are shown in Figure 1. Two aromatic rings A (C1—C6) and B (C7—C16) show a little deviation from planarity with a dihedral angle of 1.56°. Intramolecular hydrogen bonds are formed between the phenol hydroxyl groups and the nearest N atom in the aminobenze groups (Table 1).
For general background to
and their use in dyes, pigments and advanced materials, see: Lee et al. (2004); Oueslati et al. (2004).Data collection: APEX2 (Bruker, 2006); cell
SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. Ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. |
C16H12N2O | Z = 8 |
Mr = 248.28 | F(000) = 1040 |
Monoclinic, C2/c | Dx = 1.315 Mg m−3 |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 28.109 (5) Å | µ = 0.08 mm−1 |
b = 6.039 (5) Å | T = 293 K |
c = 15.181 (5) Å | Needle, red |
β = 103.243 (5)° | 0.09 × 0.04 × 0.01 mm |
V = 2508 (2) Å3 |
Bruker APEXII diffractometer | Rint = 0.034 |
Horizonally mounted graphite crystal monochromator | θmax = 26.0°, θmin = 2.8° |
CCD rotation images, thick slices scans | h = −33→34 |
4481 measured reflections | k = −7→7 |
2450 independent reflections | l = −18→18 |
1469 reflections with I > 2σ(I) |
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)] = 0.057 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.169 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.092P)2] where P = (Fo2 + 2Fc2)/3 |
2450 reflections | (Δ/σ)max < 0.001 |
176 parameters | Δρmax = 0.20 e Å−3 |
2 restraints | Δρmin = −0.20 e Å−3 |
C16H12N2O | V = 2508 (2) Å3 |
Mr = 248.28 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 28.109 (5) Å | µ = 0.08 mm−1 |
b = 6.039 (5) Å | T = 293 K |
c = 15.181 (5) Å | 0.09 × 0.04 × 0.01 mm |
β = 103.243 (5)° |
Bruker APEXII diffractometer | 1469 reflections with I > 2σ(I) |
4481 measured reflections | Rint = 0.034 |
2450 independent reflections |
R[F2 > 2σ(F2)] = 0.057 | 2 restraints |
wR(F2) = 0.169 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.20 e Å−3 |
2450 reflections | Δρmin = −0.20 e Å−3 |
176 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
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 | ||
O1 | 0.73024 (5) | 0.6381 (3) | 0.09280 (11) | 0.0762 (6) | |
N1 | 0.65766 (7) | 0.8669 (3) | 0.00890 (12) | 0.0551 (6) | |
N2 | 0.62773 (6) | 0.7373 (2) | 0.03831 (10) | 0.0496 (5) | |
C1 | 0.63841 (7) | 1.0493 (3) | −0.04642 (12) | 0.0507 (6) | |
C2 | 0.58893 (8) | 1.0917 (3) | −0.07177 (13) | 0.0581 (7) | |
C3 | 0.57264 (9) | 1.2751 (3) | −0.12414 (14) | 0.0647 (8) | |
C4 | 0.60525 (10) | 1.4165 (3) | −0.15058 (14) | 0.0668 (9) | |
C5 | 0.65432 (10) | 1.3745 (3) | −0.12602 (15) | 0.0708 (9) | |
C6 | 0.67128 (8) | 1.1886 (3) | −0.07340 (14) | 0.0627 (8) | |
C7 | 0.64663 (7) | 0.5645 (3) | 0.09114 (12) | 0.0474 (6) | |
C8 | 0.69840 (7) | 0.5157 (3) | 0.11735 (13) | 0.0571 (7) | |
C9 | 0.71329 (8) | 0.3216 (3) | 0.17167 (14) | 0.0663 (8) | |
C10 | 0.68014 (8) | 0.1878 (3) | 0.19510 (14) | 0.0629 (8) | |
C12 | 0.59514 (8) | 0.0806 (3) | 0.19309 (14) | 0.0618 (8) | |
C13 | 0.54622 (8) | 0.1209 (3) | 0.16897 (15) | 0.0667 (8) | |
C14 | 0.52907 (8) | 0.3124 (3) | 0.12094 (14) | 0.0642 (8) | |
C15 | 0.56100 (7) | 0.4592 (3) | 0.09687 (13) | 0.0560 (7) | |
C16 | 0.61175 (7) | 0.4199 (3) | 0.11928 (12) | 0.0465 (6) | |
C17 | 0.62863 (7) | 0.2274 (3) | 0.16940 (12) | 0.0511 (6) | |
H1 | 0.6900 (5) | 0.835 (4) | 0.022 (2) | 0.127 (11)* | |
H2 | 0.56680 | 0.99750 | −0.05370 | 0.0700* | |
H3 | 0.53930 | 1.30370 | −0.14180 | 0.0780* | |
H4 | 0.59390 | 1.54080 | −0.18520 | 0.0800* | |
H5 | 0.67630 | 1.46940 | −0.14430 | 0.0850* | |
H6 | 0.70460 | 1.15890 | −0.05660 | 0.0750* | |
H9 | 0.74640 | 0.28840 | 0.19080 | 0.0800* | |
H10 | 0.69120 | 0.06310 | 0.22980 | 0.0750* | |
H12 | 0.60650 | −0.04640 | 0.22580 | 0.0740* | |
H13 | 0.52430 | 0.02100 | 0.18450 | 0.0800* | |
H14 | 0.49570 | 0.34080 | 0.10510 | 0.0770* | |
H15 | 0.54900 | 0.58690 | 0.06520 | 0.0670* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0554 (9) | 0.0765 (10) | 0.0933 (12) | −0.0043 (7) | 0.0103 (8) | 0.0133 (8) |
N1 | 0.0601 (11) | 0.0475 (9) | 0.0584 (11) | 0.0026 (8) | 0.0153 (9) | 0.0031 (7) |
N2 | 0.0601 (10) | 0.0441 (8) | 0.0455 (9) | 0.0048 (7) | 0.0139 (8) | −0.0013 (7) |
C1 | 0.0666 (13) | 0.0414 (9) | 0.0457 (11) | 0.0035 (9) | 0.0160 (9) | −0.0021 (8) |
C2 | 0.0695 (14) | 0.0496 (11) | 0.0568 (13) | 0.0017 (9) | 0.0180 (11) | 0.0021 (9) |
C3 | 0.0791 (15) | 0.0538 (11) | 0.0594 (13) | 0.0129 (11) | 0.0119 (12) | 0.0008 (10) |
C4 | 0.0995 (19) | 0.0508 (11) | 0.0515 (13) | 0.0121 (12) | 0.0201 (12) | 0.0054 (9) |
C5 | 0.1042 (19) | 0.0529 (11) | 0.0638 (14) | −0.0047 (12) | 0.0371 (13) | 0.0041 (10) |
C6 | 0.0723 (14) | 0.0594 (12) | 0.0607 (13) | −0.0004 (10) | 0.0244 (11) | 0.0013 (10) |
C7 | 0.0555 (11) | 0.0441 (9) | 0.0411 (10) | 0.0051 (8) | 0.0080 (9) | −0.0020 (8) |
C8 | 0.0557 (13) | 0.0568 (11) | 0.0553 (12) | 0.0009 (10) | 0.0057 (10) | −0.0013 (9) |
C9 | 0.0566 (13) | 0.0693 (13) | 0.0664 (14) | 0.0093 (11) | 0.0003 (11) | 0.0102 (11) |
C10 | 0.0722 (15) | 0.0562 (12) | 0.0566 (12) | 0.0164 (10) | 0.0069 (11) | 0.0111 (10) |
C12 | 0.0806 (16) | 0.0512 (11) | 0.0556 (12) | 0.0085 (10) | 0.0198 (11) | 0.0076 (9) |
C13 | 0.0737 (15) | 0.0608 (12) | 0.0719 (15) | −0.0033 (11) | 0.0297 (12) | 0.0048 (11) |
C14 | 0.0583 (13) | 0.0662 (13) | 0.0704 (14) | 0.0050 (10) | 0.0195 (11) | 0.0013 (11) |
C15 | 0.0603 (13) | 0.0524 (10) | 0.0565 (12) | 0.0098 (9) | 0.0161 (10) | 0.0056 (9) |
C16 | 0.0568 (12) | 0.0436 (9) | 0.0394 (9) | 0.0064 (8) | 0.0117 (8) | −0.0039 (8) |
C17 | 0.0627 (13) | 0.0468 (10) | 0.0438 (10) | 0.0060 (9) | 0.0123 (9) | −0.0011 (8) |
O1—C8 | 1.280 (3) | C12—C13 | 1.361 (3) |
N1—N2 | 1.301 (3) | C13—C14 | 1.393 (3) |
N1—C1 | 1.415 (3) | C14—C15 | 1.369 (3) |
N2—C7 | 1.349 (3) | C15—C16 | 1.409 (3) |
N1—H1 | 0.906 (17) | C16—C17 | 1.411 (3) |
C1—C2 | 1.379 (3) | C2—H2 | 0.9300 |
C1—C6 | 1.379 (3) | C3—H3 | 0.9300 |
C2—C3 | 1.379 (3) | C4—H4 | 0.9300 |
C3—C4 | 1.378 (4) | C5—H5 | 0.9300 |
C4—C5 | 1.368 (4) | C6—H6 | 0.9300 |
C5—C6 | 1.397 (3) | C9—H9 | 0.9300 |
C7—C8 | 1.448 (3) | C10—H10 | 0.9300 |
C7—C16 | 1.449 (3) | C12—H12 | 0.9300 |
C8—C9 | 1.439 (3) | C13—H13 | 0.9300 |
C9—C10 | 1.342 (3) | C14—H14 | 0.9300 |
C10—C17 | 1.431 (3) | C15—H15 | 0.9300 |
C12—C17 | 1.399 (3) | ||
O1···N1 | 2.550 (3) | C4···H12iv | 2.9200 |
O1···N2 | 2.873 (3) | C5···H12iv | 3.0700 |
O1···H1 | 1.81 (2) | C8···H1 | 2.39 (3) |
O1···H6i | 2.7100 | C12···H4vi | 2.9400 |
N1···O1 | 2.550 (3) | C13···H4vi | 3.0800 |
N1···C10ii | 3.366 (4) | C14···H3v | 3.0700 |
N2···O1 | 2.873 (3) | C17···H4vi | 2.9600 |
N2···C4iii | 3.398 (4) | H1···O1 | 1.81 (2) |
N2···C12ii | 3.412 (4) | H1···C8 | 2.39 (3) |
N2···H2 | 2.5000 | H1···H6 | 2.3800 |
N2···H15 | 2.5100 | H2···N2 | 2.5000 |
C1···C16ii | 3.572 (4) | H3···C14v | 3.0700 |
C1···C17ii | 3.519 (4) | H3···H14v | 2.4800 |
C2···C16ii | 3.450 (4) | H4···C12vii | 2.9400 |
C4···N2ii | 3.398 (4) | H4···C13vii | 3.0800 |
C5···C7ii | 3.544 (4) | H4···C17vii | 2.9600 |
C6···C8ii | 3.443 (4) | H6···H1 | 2.3800 |
C6···C7ii | 3.559 (4) | H6···O1i | 2.7100 |
C7···C5iii | 3.544 (4) | H9···H10viii | 2.5100 |
C7···C6iii | 3.559 (4) | H10···H12 | 2.4600 |
C8···C6iii | 3.443 (4) | H10···H9ix | 2.5100 |
C10···N1iii | 3.366 (4) | H12···H10 | 2.4600 |
C12···N2iii | 3.412 (4) | H12···C3x | 3.0000 |
C16···C1iii | 3.572 (4) | H12···C4x | 2.9200 |
C16···C2iii | 3.450 (4) | H12···C5x | 3.0700 |
C17···C1iii | 3.519 (4) | H14···C3v | 3.0700 |
C3···H12iv | 3.0000 | H14···H3v | 2.4800 |
C3···H14v | 3.0700 | H15···N2 | 2.5100 |
N2—N1—C1 | 118.85 (18) | C7—C16—C15 | 122.93 (17) |
N1—N2—C7 | 118.17 (17) | C12—C17—C16 | 119.86 (18) |
N2—N1—H1 | 119.5 (16) | C10—C17—C12 | 121.51 (17) |
C1—N1—H1 | 121.6 (16) | C10—C17—C16 | 118.63 (17) |
N1—C1—C2 | 122.28 (18) | C1—C2—H2 | 120.00 |
N1—C1—C6 | 117.38 (18) | C3—C2—H2 | 120.00 |
C2—C1—C6 | 120.34 (18) | C2—C3—H3 | 120.00 |
C1—C2—C3 | 119.4 (2) | C4—C3—H3 | 120.00 |
C2—C3—C4 | 120.7 (2) | C3—C4—H4 | 120.00 |
C3—C4—C5 | 120.15 (19) | C5—C4—H4 | 120.00 |
C4—C5—C6 | 119.7 (2) | C4—C5—H5 | 120.00 |
C1—C6—C5 | 119.7 (2) | C6—C5—H5 | 120.00 |
C8—C7—C16 | 120.11 (16) | C1—C6—H6 | 120.00 |
N2—C7—C8 | 123.70 (17) | C5—C6—H6 | 120.00 |
N2—C7—C16 | 116.15 (17) | C8—C9—H9 | 120.00 |
C7—C8—C9 | 117.72 (18) | C10—C9—H9 | 120.00 |
O1—C8—C9 | 120.41 (19) | C9—C10—H10 | 118.00 |
O1—C8—C7 | 121.87 (17) | C17—C10—H10 | 118.00 |
C8—C9—C10 | 120.9 (2) | C13—C12—H12 | 120.00 |
C9—C10—C17 | 123.23 (18) | C17—C12—H12 | 119.00 |
C13—C12—C17 | 121.02 (18) | C12—C13—H13 | 120.00 |
C12—C13—C14 | 119.8 (2) | C14—C13—H13 | 120.00 |
C13—C14—C15 | 120.5 (2) | C13—C14—H14 | 120.00 |
C14—C15—C16 | 121.05 (18) | C15—C14—H14 | 120.00 |
C7—C16—C17 | 119.28 (18) | C14—C15—H15 | 119.00 |
C15—C16—C17 | 117.77 (17) | C16—C15—H15 | 119.00 |
C1—N1—N2—C7 | −179.84 (16) | C8—C7—C16—C15 | 179.34 (17) |
N2—N1—C1—C2 | −1.4 (3) | C8—C7—C16—C17 | −2.4 (3) |
N2—N1—C1—C6 | 177.41 (17) | O1—C8—C9—C10 | −177.61 (19) |
N1—N2—C7—C8 | 0.3 (3) | C7—C8—C9—C10 | 1.7 (3) |
N1—N2—C7—C16 | −177.64 (16) | C8—C9—C10—C17 | −0.6 (3) |
N1—C1—C2—C3 | 178.57 (18) | C9—C10—C17—C12 | 178.22 (19) |
C6—C1—C2—C3 | −0.2 (3) | C9—C10—C17—C16 | −2.0 (3) |
N1—C1—C6—C5 | −178.28 (18) | C17—C12—C13—C14 | −0.8 (3) |
C2—C1—C6—C5 | 0.5 (3) | C13—C12—C17—C10 | 179.41 (19) |
C1—C2—C3—C4 | −0.5 (3) | C13—C12—C17—C16 | −0.4 (3) |
C2—C3—C4—C5 | 0.9 (3) | C12—C13—C14—C15 | 0.8 (3) |
C3—C4—C5—C6 | −0.5 (3) | C13—C14—C15—C16 | 0.5 (3) |
C4—C5—C6—C1 | −0.2 (3) | C14—C15—C16—C7 | 176.67 (18) |
N2—C7—C8—O1 | 1.2 (3) | C14—C15—C16—C17 | −1.7 (3) |
N2—C7—C8—C9 | −178.06 (17) | C7—C16—C17—C10 | 3.4 (3) |
C16—C7—C8—O1 | 179.10 (18) | C7—C16—C17—C12 | −176.80 (17) |
C16—C7—C8—C9 | −0.2 (3) | C15—C16—C17—C10 | −178.21 (17) |
N2—C7—C16—C15 | −2.6 (3) | C15—C16—C17—C12 | 1.6 (3) |
N2—C7—C16—C17 | 175.67 (16) |
Symmetry codes: (i) −x+3/2, −y+3/2, −z; (ii) x, y+1, z; (iii) x, y−1, z; (iv) x, −y+1, z−1/2; (v) −x+1, −y+2, −z; (vi) x, −y+2, z+1/2; (vii) x, −y+2, z−1/2; (viii) −x+3/2, y+1/2, −z+1/2; (ix) −x+3/2, y−1/2, −z+1/2; (x) x, −y+1, z+1/2. |
Cg1 and Cg3 are the centroids of the C1–C6 and C12–C17 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1 | 0.906 (17) | 1.81 (2) | 2.550 (3) | 137 (2) |
C4—H4···Cg3vii | 0.93 | 2.76 | 3.568 (4) | 145 |
C12—H12···Cg1x | 0.93 | 2.83 | 3.612 (4) | 142 |
Symmetry codes: (vii) x, −y+2, z−1/2; (x) x, −y+1, z+1/2. |
Cg1 and Cg3 are the centroids of the C1–C6 and C12–C17 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1 | 0.906 (17) | 1.81 (2) | 2.550 (3) | 137 (2) |
C4—H4···Cg3i | 0.93 | 2.76 | 3.568 (4) | 145 |
C12—H12···Cg1ii | 0.93 | 2.83 | 3.612 (4) | 142 |
Symmetry codes: (i) x, −y+2, z−1/2; (ii) x, −y+1, z+1/2. |
References
Bruker (2006). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Lee, S. H., Kim, J. Y., Ko, J., Lee, J. Y. & Kim, J. S. (2004). J. Org. Chem. 69, 2902–2905. Web of Science CrossRef PubMed CAS Google Scholar
Oueslati, F., Dumazet-Bonnamour, I. & Lamartine, R. (2004). New J. Chem. 28, 1575–1578. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
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The azo dyes are by far the most important class, accounting for over 50% of all commercial dyes, and having been studied more than other class (Lee et al., 2004; Oueslati et al., 2004). Azo dyes contain at least one azo group (–N=N–) but can contain two (diazo), three(triazo), or, more rarely, four (tetrakisazo) or more (polyazo) azo groups. The azo group is attached to two groups, of which at least one, but more usually both are aromatic. They exist in the Trans form in which the band angle is 120°, the nitrogen atoms are sp2 hybridized. Almost without exception, azo dyes are made by diazotization of primary aromatic amine followed by coupling of the resultant diazonium salt with an electron-richnucleophile. We report here in the crystal structure of the title compound, obtained through the diazotization of aniline followed by a coupling reaction with2-naphthol.
The molecular structure of (I) and the atom-numbering scheme are shown in Figure 1. Two aromatic rings A (C1—C6) and B (C7—C16) show a little deviation from planarity with a dihedral angle of 1.56°. Intramolecular hydrogen bonds are formed between the phenol hydroxyl groups and the nearest N atom in the aminobenze groups (Table 1).