Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536810015230/rz2436sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536810015230/rz2436Isup2.hkl |
CCDC reference: 781267
Key indicators
- Single-crystal X-ray study
- T = 100 K
- Mean (C-C) = 0.003 Å
- R factor = 0.018
- wR factor = 0.041
- Data-to-parameter ratio = 16.3
checkCIF/PLATON results
No syntax errors found
Alert level C CHEMW01_ALERT_1_C The difference between the given and expected weight for compound is greater 1 mass unit. Check that all hydrogen atoms have been taken into account. PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density .... 2.04 PLAT222_ALERT_3_C Large Non-Solvent H Ueq(max)/Ueq(min) ... 4.00 Ratio PLAT309_ALERT_2_C Single Bonded Oxygen (C-O .GT. 1.3 Ang) ........ O1 PLAT432_ALERT_2_C Short Inter X...Y Contact C7 .. C9 .. 3.18 Ang. PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L= 0.600 3 PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L= 0.600 2
Alert level G REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 30.00 From the CIF: _reflns_number_total 3120 Count of symmetry unique reflns 1645 Completeness (_total/calc) 189.67% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 1475 Fraction of Friedel pairs measured 0.897 Are heavy atom types Z>Si present yes PLAT164_ALERT_4_G Nr. of Refined C-H H-Atoms in Heavy-Atom Struct. 8 PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels .......... 2 PLAT931_ALERT_5_G Check Twin Law ( 1 0 0)[ ] Estimated BASF 0.10 PLAT931_ALERT_5_G Check Twin Law ( )[ 1 0 0] Estimated BASF 0.10
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 7 ALERT level C = Check and explain 5 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 3 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 4 ALERT type 4 Improvement, methodology, query or suggestion 2 ALERT type 5 Informative message, check
The title compound was synthesized by adding 5-bromo-2-hydroxybenzaldehyde (0.402 g, 2 mmol) to a solution of 2-aminophenol (0.218 g, 2 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for half an hour. The resultant yellow solution was filtered and the filtrate was evaporated to give a yellow solid product. Yellow needle-shaped single crystals of the title compound suitable for x-ray structure determination were obtained from ethanol by slow evaporation at room temperature after nine days.
Hydroxyl H atom was placed in calculated positions with d(O—H) = 0.82 Å and the Uiso values was constrained to be 1.5Ueq of the carrier atom. The remaining H atoms were located from the difference map and isotropically refined. The highest residual electron density peak is located at 0.80 Å from Br1 and the deepest hole is located at 0.99 Å from Br1. The crystal studied was a twin with twin law 1 0 0, 0 1 0, 0 0 1, leading to a distribution (refined BASF parameter) of 0.09919/0.90081 (2).
Much attention has been given to Schiff base ligands due to their applications such as in coordination chemistry (Kagkelari et al., 2009), chelated boron catalyst (Wei & Atwood, 1998), pharmacological activities, anticancer (Dao et al., 2000), anti-HIV (Sriram et al., 2006), antibacterial and antifungal (Karthikeyan et al., 2006) activities. We have reported the crystal structures of Schiff base ligands which existed in a zwitterionic form i.e 2-((E)-{2-[(E)-2,3-dihydroxybenzylideneamino]-5-methylphenyl}- iminiomethyl)-6-hydroxyphenolate (Eltayeb et al., 2009) and (E)-4-allyl-2-{[(2-hydroxyphenyl)iminio]methyl}-6-methoxyphenolate (Eltayeb et al., 2010). Herein we report the crystal structure of the title zwitterionic Schiff base ligand (I).
The molecule of (I) (Fig. 1), C13H9BrNO2, crystallizes in a zwitterionic form with cationic iminium and anionic enolate, and exists in a trans configuration about the C═N bond [1.310 (2) Å]; the torsion angle C8–N1–C7–C6 is 179.25 (17)°. The molecule is almost planar with the dihedral angle between the two benzene rings of 2.31 (9)°. The hydroxy group is co-planar with the attached C8–C13 benzene ring with the r.m.s. of 0.0102 (2) Å for the seven non H atoms. Intramolecular N—H···O hydrogen bond between the NH+ and the phenolate O- generates an S(6) ring motif (Fig. 1; Table 1) which help to stabilize the planarity of the molecule (Bernstein et al., 1995). The bond distances are in normal ranges (Allen et al., 1987) and comparable with those found in related structures (Eltayeb et al., 2009, 2010; Tan & Liu, 2009).
In the crystal packing (Fig. 2), the zwitterions are linked through O2–H1O2···O1 hydrogen bonds into chains along the [101] and these chains are further connected through C11—H11A···Br1 interactions into a 2-D network perpendicular to the (101)-plane. The crystal is stabilized by O—H···O and weak C—H···Br interactions (Table 1). C···C [3.572 (3)-3.592 (3) Å] and C···Br [3.5633 (19)-3.7339 (18) Å] short contacts are observed.
For bond-length data, see: Allen et al. (1987). For hydrogen-bond motifs, see: Bernstein et al. (1995). For background to Schiff bases and their applications, see: Dao et al. (2000); Kagkelari et al. (2009); Karthikeyan et al. (2006); Sriram et al. (2006); Wei & Atwood (1998). For related structures, see: Eltayeb et al. (2009; 2010); Tan & Liu (2009). For the stability of the temperature controller used in the data collection, see Cosier & Glazer, (1986).
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
C13H10BrNO2 | F(000) = 292 |
Mr = 291.12 | Dx = 1.773 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 3120 reflections |
a = 4.6387 (3) Å | θ = 1.1–30.0° |
b = 18.9379 (13) Å | µ = 3.74 mm−1 |
c = 6.2270 (4) Å | T = 100 K |
β = 90.144 (3)° | Needle, yellow |
V = 547.02 (6) Å3 | 0.43 × 0.14 × 0.14 mm |
Z = 2 |
Bruker APEXII DUO CCD area-detector diffractometer | 3120 independent reflections |
Radiation source: sealed tube | 3034 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.026 |
φ and ω scans | θmax = 30.0°, θmin = 1.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −6→6 |
Tmin = 0.295, Tmax = 0.628 | k = −26→26 |
8575 measured reflections | l = −8→8 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.018 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.041 | w = 1/[σ2(Fo2) + (0.0035P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.02 | (Δ/σ)max < 0.001 |
3120 reflections | Δρmax = 0.59 e Å−3 |
191 parameters | Δρmin = −0.29 e Å−3 |
1 restraint | Absolute structure: Flack (1983), 1480 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.027 (7) |
C13H10BrNO2 | V = 547.02 (6) Å3 |
Mr = 291.12 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 4.6387 (3) Å | µ = 3.74 mm−1 |
b = 18.9379 (13) Å | T = 100 K |
c = 6.2270 (4) Å | 0.43 × 0.14 × 0.14 mm |
β = 90.144 (3)° |
Bruker APEXII DUO CCD area-detector diffractometer | 3120 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 3034 reflections with I > 2σ(I) |
Tmin = 0.295, Tmax = 0.628 | Rint = 0.026 |
8575 measured reflections |
R[F2 > 2σ(F2)] = 0.018 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.041 | Δρmax = 0.59 e Å−3 |
S = 1.02 | Δρmin = −0.29 e Å−3 |
3120 reflections | Absolute structure: Flack (1983), 1480 Friedel pairs |
191 parameters | Absolute structure parameter: 0.027 (7) |
1 restraint |
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 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. |
x | y | z | Uiso*/Ueq | ||
Br1 | 0.00526 (4) | 0.442840 (15) | 0.87673 (2) | 0.01554 (4) | |
O1 | 0.5191 (3) | 0.66300 (7) | 0.29008 (19) | 0.0152 (2) | |
O2 | 1.1314 (3) | 0.70088 (8) | 1.0194 (2) | 0.0166 (3) | |
H1O2 | 1.2697 | 0.6925 | 1.0976 | 0.025* | |
N1 | 0.8565 (3) | 0.69973 (8) | 0.6076 (2) | 0.0121 (3) | |
H1N1 | 0.802 (6) | 0.6976 (16) | 0.470 (5) | 0.026 (7)* | |
C1 | 0.4132 (4) | 0.61426 (10) | 0.4149 (3) | 0.0126 (3) | |
C2 | 0.1934 (4) | 0.56695 (10) | 0.3446 (3) | 0.0140 (3) | |
H2A | 0.133 (6) | 0.5756 (14) | 0.207 (4) | 0.020 (6)* | |
C3 | 0.0797 (4) | 0.51628 (10) | 0.4781 (3) | 0.0138 (3) | |
H3A | −0.064 (6) | 0.4852 (14) | 0.440 (4) | 0.021 (6)* | |
C4 | 0.1776 (4) | 0.51058 (9) | 0.6919 (3) | 0.0129 (3) | |
C5 | 0.3894 (4) | 0.55482 (9) | 0.7685 (3) | 0.0125 (3) | |
H5A | 0.450 (6) | 0.5535 (16) | 0.905 (4) | 0.026 (7)* | |
C6 | 0.5112 (4) | 0.60653 (9) | 0.6331 (3) | 0.0122 (3) | |
C7 | 0.7261 (4) | 0.65154 (9) | 0.7227 (3) | 0.0123 (3) | |
H7A | 0.787 (5) | 0.6470 (12) | 0.868 (4) | 0.009 (5)* | |
C8 | 1.0707 (4) | 0.74911 (9) | 0.6695 (3) | 0.0117 (3) | |
C9 | 1.2064 (4) | 0.74952 (9) | 0.8722 (3) | 0.0125 (3) | |
C10 | 1.4149 (4) | 0.80132 (10) | 0.9137 (3) | 0.0148 (3) | |
H10A | 1.494 (6) | 0.8047 (15) | 1.048 (5) | 0.022 (6)* | |
C11 | 1.4940 (4) | 0.84982 (10) | 0.7569 (3) | 0.0159 (3) | |
H11A | 1.639 (6) | 0.8847 (13) | 0.786 (4) | 0.018 (6)* | |
C12 | 1.3635 (4) | 0.84799 (10) | 0.5548 (3) | 0.0160 (3) | |
H12A | 1.427 (7) | 0.8788 (17) | 0.453 (5) | 0.036 (8)* | |
C13 | 1.1523 (4) | 0.79797 (9) | 0.5130 (3) | 0.0139 (3) | |
H13A | 1.045 (5) | 0.7956 (13) | 0.368 (3) | 0.014 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.01876 (7) | 0.01522 (7) | 0.01262 (6) | −0.00425 (9) | −0.00307 (5) | 0.00324 (8) |
O1 | 0.0161 (6) | 0.0183 (6) | 0.0113 (5) | −0.0031 (5) | −0.0034 (5) | 0.0033 (5) |
O2 | 0.0167 (6) | 0.0224 (7) | 0.0106 (6) | −0.0044 (5) | −0.0054 (5) | 0.0042 (5) |
N1 | 0.0122 (7) | 0.0140 (7) | 0.0102 (7) | −0.0004 (5) | −0.0033 (5) | 0.0003 (5) |
C1 | 0.0122 (7) | 0.0150 (8) | 0.0106 (7) | 0.0001 (6) | −0.0012 (5) | −0.0002 (6) |
C2 | 0.0156 (8) | 0.0172 (8) | 0.0092 (8) | −0.0007 (6) | −0.0030 (6) | −0.0007 (6) |
C3 | 0.0136 (8) | 0.0141 (8) | 0.0137 (8) | −0.0022 (6) | −0.0024 (6) | −0.0018 (6) |
C4 | 0.0142 (8) | 0.0120 (7) | 0.0126 (8) | −0.0007 (6) | −0.0003 (6) | 0.0015 (6) |
C5 | 0.0150 (8) | 0.0137 (8) | 0.0087 (8) | 0.0011 (6) | −0.0030 (6) | 0.0007 (6) |
C6 | 0.0116 (7) | 0.0140 (7) | 0.0109 (7) | 0.0014 (6) | −0.0014 (6) | −0.0021 (6) |
C7 | 0.0123 (8) | 0.0139 (8) | 0.0108 (8) | 0.0003 (6) | −0.0020 (6) | −0.0007 (6) |
C8 | 0.0114 (7) | 0.0114 (7) | 0.0122 (7) | 0.0001 (6) | −0.0033 (5) | −0.0010 (6) |
C9 | 0.0127 (7) | 0.0146 (8) | 0.0103 (7) | 0.0003 (6) | −0.0012 (6) | −0.0007 (6) |
C10 | 0.0146 (8) | 0.0174 (9) | 0.0123 (8) | −0.0012 (6) | −0.0044 (6) | −0.0020 (6) |
C11 | 0.0141 (8) | 0.0154 (8) | 0.0182 (8) | −0.0021 (7) | −0.0016 (7) | −0.0017 (6) |
C12 | 0.0172 (9) | 0.0147 (8) | 0.0161 (8) | −0.0007 (7) | −0.0011 (6) | 0.0022 (7) |
C13 | 0.0128 (8) | 0.0160 (8) | 0.0129 (8) | 0.0008 (6) | −0.0026 (6) | 0.0011 (6) |
Br1—C4 | 1.9011 (18) | C5—C6 | 1.411 (2) |
O1—C1 | 1.304 (2) | C5—H5A | 0.89 (2) |
O2—C9 | 1.346 (2) | C6—C7 | 1.424 (2) |
O2—H1O2 | 0.8200 | C7—H7A | 0.95 (2) |
N1—C7 | 1.310 (2) | C8—C13 | 1.397 (2) |
N1—C8 | 1.417 (2) | C8—C9 | 1.409 (2) |
N1—H1N1 | 0.89 (3) | C9—C10 | 1.401 (2) |
C1—C2 | 1.425 (2) | C10—C11 | 1.391 (3) |
C1—C6 | 1.439 (2) | C10—H10A | 0.92 (3) |
C2—C3 | 1.376 (3) | C11—C12 | 1.396 (3) |
C2—H2A | 0.91 (3) | C11—H11A | 0.96 (3) |
C3—C4 | 1.409 (2) | C12—C13 | 1.387 (3) |
C3—H3A | 0.92 (3) | C12—H12A | 0.91 (3) |
C4—C5 | 1.376 (3) | C13—H13A | 1.03 (2) |
C9—O2—H1O2 | 109.5 | N1—C7—C6 | 121.74 (16) |
C7—N1—C8 | 129.42 (16) | N1—C7—H7A | 116.6 (14) |
C7—N1—H1N1 | 111.3 (19) | C6—C7—H7A | 121.6 (14) |
C8—N1—H1N1 | 119.2 (18) | C13—C8—C9 | 120.02 (16) |
O1—C1—C2 | 122.15 (15) | C13—C8—N1 | 115.98 (15) |
O1—C1—C6 | 121.08 (16) | C9—C8—N1 | 123.97 (16) |
C2—C1—C6 | 116.76 (16) | O2—C9—C10 | 122.23 (15) |
C3—C2—C1 | 121.85 (16) | O2—C9—C8 | 119.39 (15) |
C3—C2—H2A | 125.0 (16) | C10—C9—C8 | 118.39 (16) |
C1—C2—H2A | 113.1 (17) | C11—C10—C9 | 121.08 (16) |
C2—C3—C4 | 120.08 (16) | C11—C10—H10A | 119.3 (18) |
C2—C3—H3A | 124.6 (16) | C9—C10—H10A | 119.6 (17) |
C4—C3—H3A | 115.3 (16) | C10—C11—C12 | 120.15 (17) |
C5—C4—C3 | 120.59 (16) | C10—C11—H11A | 120.5 (15) |
C5—C4—Br1 | 120.14 (13) | C12—C11—H11A | 119.4 (15) |
C3—C4—Br1 | 119.24 (13) | C13—C12—C11 | 119.38 (17) |
C4—C5—C6 | 120.14 (16) | C13—C12—H12A | 122 (2) |
C4—C5—H5A | 122 (2) | C11—C12—H12A | 118 (2) |
C6—C5—H5A | 118 (2) | C12—C13—C8 | 120.94 (16) |
C5—C6—C7 | 117.51 (15) | C12—C13—H13A | 122.2 (13) |
C5—C6—C1 | 120.57 (16) | C8—C13—H13A | 116.8 (13) |
C7—C6—C1 | 121.89 (16) | ||
O1—C1—C2—C3 | −179.04 (17) | C1—C6—C7—N1 | −3.8 (3) |
C6—C1—C2—C3 | 0.1 (3) | C7—N1—C8—C13 | −175.04 (17) |
C1—C2—C3—C4 | 0.8 (3) | C7—N1—C8—C9 | 7.1 (3) |
C2—C3—C4—C5 | −0.8 (3) | C13—C8—C9—O2 | −178.12 (16) |
C2—C3—C4—Br1 | 177.31 (14) | N1—C8—C9—O2 | −0.3 (3) |
C3—C4—C5—C6 | 0.0 (3) | C13—C8—C9—C10 | 2.3 (3) |
Br1—C4—C5—C6 | −178.09 (13) | N1—C8—C9—C10 | −179.92 (17) |
C4—C5—C6—C7 | 178.93 (16) | O2—C9—C10—C11 | 178.26 (18) |
C4—C5—C6—C1 | 0.8 (3) | C8—C9—C10—C11 | −2.1 (3) |
O1—C1—C6—C5 | 178.25 (17) | C9—C10—C11—C12 | 0.6 (3) |
C2—C1—C6—C5 | −0.8 (2) | C10—C11—C12—C13 | 0.8 (3) |
O1—C1—C6—C7 | 0.2 (3) | C11—C12—C13—C8 | −0.6 (3) |
C2—C1—C6—C7 | −178.85 (16) | C9—C8—C13—C12 | −0.9 (3) |
C8—N1—C7—C6 | 179.25 (17) | N1—C8—C13—C12 | −178.91 (16) |
C5—C6—C7—N1 | 178.12 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H1O2···O1i | 0.82 | 1.76 | 2.5641 (19) | 169 |
N1—H1N1···O1 | 0.89 (3) | 1.84 (3) | 2.6129 (18) | 143 (3) |
C7—H7A···O2 | 0.95 (2) | 2.12 (2) | 2.794 (2) | 127.1 (18) |
C11—H11A···Br1ii | 0.96 (3) | 2.89 (3) | 3.6982 (19) | 143.1 (19) |
Symmetry codes: (i) x+1, y, z+1; (ii) −x+2, y+1/2, −z+2. |
Experimental details
Crystal data | |
Chemical formula | C13H10BrNO2 |
Mr | 291.12 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 100 |
a, b, c (Å) | 4.6387 (3), 18.9379 (13), 6.2270 (4) |
β (°) | 90.144 (3) |
V (Å3) | 547.02 (6) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 3.74 |
Crystal size (mm) | 0.43 × 0.14 × 0.14 |
Data collection | |
Diffractometer | Bruker APEXII DUO CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2009) |
Tmin, Tmax | 0.295, 0.628 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8575, 3120, 3034 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.018, 0.041, 1.02 |
No. of reflections | 3120 |
No. of parameters | 191 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.59, −0.29 |
Absolute structure | Flack (1983), 1480 Friedel pairs |
Absolute structure parameter | 0.027 (7) |
Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H1O2···O1i | 0.82 | 1.76 | 2.5641 (19) | 169 |
N1—H1N1···O1 | 0.89 (3) | 1.84 (3) | 2.6129 (18) | 143 (3) |
C7—H7A···O2 | 0.95 (2) | 2.12 (2) | 2.794 (2) | 127.1 (18) |
C11—H11A···Br1ii | 0.96 (3) | 2.89 (3) | 3.6982 (19) | 143.1 (19) |
Symmetry codes: (i) x+1, y, z+1; (ii) −x+2, y+1/2, −z+2. |
Much attention has been given to Schiff base ligands due to their applications such as in coordination chemistry (Kagkelari et al., 2009), chelated boron catalyst (Wei & Atwood, 1998), pharmacological activities, anticancer (Dao et al., 2000), anti-HIV (Sriram et al., 2006), antibacterial and antifungal (Karthikeyan et al., 2006) activities. We have reported the crystal structures of Schiff base ligands which existed in a zwitterionic form i.e 2-((E)-{2-[(E)-2,3-dihydroxybenzylideneamino]-5-methylphenyl}- iminiomethyl)-6-hydroxyphenolate (Eltayeb et al., 2009) and (E)-4-allyl-2-{[(2-hydroxyphenyl)iminio]methyl}-6-methoxyphenolate (Eltayeb et al., 2010). Herein we report the crystal structure of the title zwitterionic Schiff base ligand (I).
The molecule of (I) (Fig. 1), C13H9BrNO2, crystallizes in a zwitterionic form with cationic iminium and anionic enolate, and exists in a trans configuration about the C═N bond [1.310 (2) Å]; the torsion angle C8–N1–C7–C6 is 179.25 (17)°. The molecule is almost planar with the dihedral angle between the two benzene rings of 2.31 (9)°. The hydroxy group is co-planar with the attached C8–C13 benzene ring with the r.m.s. of 0.0102 (2) Å for the seven non H atoms. Intramolecular N—H···O hydrogen bond between the NH+ and the phenolate O- generates an S(6) ring motif (Fig. 1; Table 1) which help to stabilize the planarity of the molecule (Bernstein et al., 1995). The bond distances are in normal ranges (Allen et al., 1987) and comparable with those found in related structures (Eltayeb et al., 2009, 2010; Tan & Liu, 2009).
In the crystal packing (Fig. 2), the zwitterions are linked through O2–H1O2···O1 hydrogen bonds into chains along the [101] and these chains are further connected through C11—H11A···Br1 interactions into a 2-D network perpendicular to the (101)-plane. The crystal is stabilized by O—H···O and weak C—H···Br interactions (Table 1). C···C [3.572 (3)-3.592 (3) Å] and C···Br [3.5633 (19)-3.7339 (18) Å] short contacts are observed.