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Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 6| June 2013| Pages o903-o904

4-[(E)-(4-Eth­­oxy­benzyl­­idene)amino]­phenol

aDepartment of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand, bDepartment of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand, cFaculty of Traditional Thai Medicine, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand, dX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and eDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia
*Correspondence e-mail: suchada.c@psu.ac.th

(Received 24 April 2013; accepted 8 May 2013; online 18 May 2013)

The mol­ecule of the title compound, C15H15NO2, adopts a trans conformation with respect to the methyl­idene C=N bond and is twisted with a dihedral angle of 26.31 (5)° between the two substituted benzene rings. The eth­oxy group is almost coplanar with the bound benzene ring with a C—O—C—C torsion angle of −179.08 (9)°. In the crystal, mol­ecules are linked by O—H⋯N hydrogen bonds and weak C—H⋯O inter­actions into chains propagating in the [011] and [01-1] directions. C—H⋯π inter­actions are also present.

Related literature

For standard bond lengths, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-S19.]). For background to and applications of aza-stilbene, see: Cheng et al. (2010[Cheng, L.-X., Tang, J.-J., Luo, H., Jin, X.-L., Dai, F., Yang, J., Qian, Y.-P., Li, X.-Z. & Zhou, B. (2010). Bioorg. Med. Chem. Lett. 20, 2417-2420.]); da Silva et al. (2011[Silva, C. M. da, da Silva, D. L., Martins, C. V. B., de Resende, M. A., Dias, E. S., Magalhaes, T. F. F., Rodrigues, L. P., Sabino, A. A., Alves, R. B. & de Fatima, A. (2011). Chem. Biol. Drug Des. 78, 810-815.]); Kabir et al. (2008[Kabir, M. S., Engelbrecht, K., Polanowski, R., Krueger, S. M., Ignasiak, R., Rott, M., Schwan, W. R., Stemper, M. E., Reed, K. D., Sherman, D., Cook, J. M. & Monte, A. (2008). Bioorg. Med. Chem. Lett. 18, 5745-5749.]); Lu et al. (2012[Lu, J., Li, C., Chai, Y.-F., Yang, D.-Y. & Sun, C.-R. (2012). Bioorg. Med. Chem. Lett. 22, 5744-5747.]); Pavan et al. (2011[Pavan, F. R., de Carvalho, G. S. G., da Silva, A. D. & Leite, C. Q. F. (2011). Sci. World J. 11, 1113-1119.]). For related structures, see: Sun et al. (2011[Sun, L.-X., Yu, Y.-D. & Wei, G.-Y. (2011). Acta Cryst. E67, o1578.]); Wang (2009[Wang, C.-Y. (2009). Acta Cryst. E65, o741.]).

[Scheme 1]

Experimental

Crystal data
  • C15H15NO2

  • Mr = 241.28

  • Orthorhombic, P n a 21

  • a = 18.6882 (11) Å

  • b = 10.7420 (6) Å

  • c = 6.3186 (4) Å

  • V = 1268.45 (13) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.08 mm−1

  • T = 100 K

  • 0.59 × 0.27 × 0.25 mm

Data collection
  • Bruker SMART APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS, Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.952, Tmax = 0.979

  • 16922 measured reflections

  • 2382 independent reflections

  • 2319 reflections with I > 2σ(I)

  • Rint = 0.025

Refinement
  • R[F2 > 2σ(F2)] = 0.030

  • wR(F2) = 0.086

  • S = 1.10

  • 2382 reflections

  • 168 parameters

  • 1 restraint

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.35 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C8–C13 ring.

D—H⋯A D—H H⋯A DA D—H⋯A
O2—H1O2⋯N1i 0.83 (2) 1.87 (2) 2.6971 (12) 172 (2)
C6—H6A⋯O2ii 0.95 2.51 3.3956 (14) 156
C9—H9A⋯O2iii 0.95 2.38 3.3229 (13) 171
C14—H14BCg1iv 0.99 2.90 3.7668 (12) 147
Symmetry codes: (i) [-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z+{\script{1\over 2}}]; (ii) [-x+{\script{3\over 2}}, y+{\script{1\over 2}}, z-{\script{1\over 2}}]; (iii) [-x+{\script{3\over 2}}, y+{\script{1\over 2}}, z+{\script{1\over 2}}]; (iv) [-x+2, -y+1, z-{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS, Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS, Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

Aza-stilbene derivatives derived from the reaction of an aldehyde with hydrazine have been shown to possess potent biological activities such as antibacterial (Kabir et al., 2008), antifungal (da Silva et al., 2011), antimycobacterium tuberculosis (Pavan et al., 2011) and antioxidation (Cheng et al., 2010; Lu et al., 2012) properties. These interesting biological activities of aza-stilbene led us to synthesize the title compound, (I), and study its antibacterial activity. Our antibacterial assay showed that (I) exhibits moderate activity against Salmonella typhi with the minimun inhibition concentration (MIC) value of 18.75 µg/ml. We report here the crystal structure of the title compound.

The molecule of (I) (Fig. 1), C15H15NO2, is twisted and exists in a trans configuration with respect to the methylidene C7N1 double bond [1.2867 (13) Å] with the torsion angle C8–N1–C7–C1 = 179.23 (8)°. The dihedral angle between the two substituted benzene rings is 26.31 (5)°. The ethoxy group is co-planar with the bound benzene ring with the r.m.s. deviation of 0.0155 (1) Å for the nine non H-atoms and the C4–O1–C14–C15 angle is -179.08 (9)°. The bond distances are within the normal range (Allen et al., 1987) and are in agreement with those reported for related structures (Sun et al., 2011; Wang, 2009).

In the crystal structure (Fig. 2), the molecules are linked by O–H···N hydrogen bond and weak C—H···O interactions (Table 1) into chains propagating in the [011] and [011] directions. C—H···π interactions between the ethoxy group and the hydroxy substituted rings are also present (Table 1).

Related literature top

For standard bond lengths, see: Allen et al. (1987). For background to and applications of aza-stilbene, see: Cheng et al. (2010); da Silva et al. (2011); Kabir et al. (2008); Lu et al. (2012); Pavan et al. (2011). For related structures, see: Sun et al. (2011); Wang (2009).

Experimental top

The title compound (I) was prepared by dissolving 4-benzylideneaniline (5 mmol, 0.50 g) in ethanol (30 ml) and 4-ethoxybenzaldehyde (5 mmol, 0.70 ml) was slowly added with stirring. The solution was stirred at room temperature for around 3 hr yielding a white solid, which was filtered off and washed with cold ethanol and dried in air. Colourless block-shaped single crystals of (I) suitable for X-ray structure determination were recrystallized from methanol by slow evaporation at room temperature after several days, M. p. 470–472 K.

Refinement top

The hydroxyl H atom was located in a difference map and refined isotropically. The remaining H atoms were fixed geometrically and allowed to ride on their parent atoms, with d(C—H) = 0.95 Å for aromatic and CH, 0.99 Å for CH2 and 0.98 Å for CH3 atoms. The Uiso values were constrained to be 1.5Ueq of the carrier atom for methyl H atoms and 1.2Ueq for the remaining H atoms. A rotating group model was used for the methyl group. 1762 Friedel pairs were merged as there is insufficient anomalous dispersion to determine the absolute structure since Mo radiation was used for data collection.

Computing details top

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).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound showing 65% probability displacement ellipsoids.
[Figure 2] Fig. 2. Crystal packing of the title compound viewed along the c axis. Hydrogen bonds are drawn as dashed lines.
4-[(E)-(4-Ethoxybenzylidene)amino]phenol top
Crystal data top
C15H15NO2Dx = 1.263 Mg m3
Mr = 241.28Melting point = 470–472 K
Orthorhombic, Pna21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2nCell parameters from 2382 reflections
a = 18.6882 (11) Åθ = 2.2–32.0°
b = 10.7420 (6) ŵ = 0.08 mm1
c = 6.3186 (4) ÅT = 100 K
V = 1268.45 (13) Å3Block, colourless
Z = 40.59 × 0.27 × 0.25 mm
F(000) = 512
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
2382 independent reflections
Radiation source: fine-focus sealed tube2319 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.025
Detector resolution: 8.33 pixels mm-1θmax = 32.0°, θmin = 2.2°
ω scansh = 2727
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
k = 1615
Tmin = 0.952, Tmax = 0.979l = 99
16922 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.086H atoms treated by a mixture of independent and constrained refinement
S = 1.10 w = 1/[σ2(Fo2) + (0.0562P)2 + 0.1397P]
where P = (Fo2 + 2Fc2)/3
2382 reflections(Δ/σ)max = 0.001
168 parametersΔρmax = 0.35 e Å3
1 restraintΔρmin = 0.19 e Å3
Crystal data top
C15H15NO2V = 1268.45 (13) Å3
Mr = 241.28Z = 4
Orthorhombic, Pna21Mo Kα radiation
a = 18.6882 (11) ŵ = 0.08 mm1
b = 10.7420 (6) ÅT = 100 K
c = 6.3186 (4) Å0.59 × 0.27 × 0.25 mm
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
2382 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
2319 reflections with I > 2σ(I)
Tmin = 0.952, Tmax = 0.979Rint = 0.025
16922 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0301 restraint
wR(F2) = 0.086H atoms treated by a mixture of independent and constrained refinement
S = 1.10Δρmax = 0.35 e Å3
2382 reflectionsΔρmin = 0.19 e Å3
168 parameters
Special details top

Experimental. The data was collected with the Oxford Cryosystem Cobra low-temperature attachment.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O11.07262 (4)0.90374 (7)0.65280 (16)0.02092 (17)
O20.68429 (4)0.01683 (7)0.72655 (13)0.01662 (15)
H1O20.6732 (11)0.000 (2)0.851 (4)0.038 (5)*
N10.85372 (4)0.43914 (7)0.61658 (15)0.01367 (16)
C10.93803 (5)0.59761 (9)0.72367 (18)0.01420 (18)
C20.97668 (5)0.64779 (9)0.89339 (19)0.01686 (19)
H2A0.97250.61131.02980.020*
C31.02104 (6)0.75025 (10)0.86479 (19)0.0181 (2)
H3A1.04680.78350.98130.022*
C41.02770 (5)0.80430 (9)0.66463 (19)0.01595 (19)
C50.98933 (6)0.75587 (10)0.49369 (19)0.01789 (19)
H5A0.99340.79280.35760.021*
C60.94517 (6)0.65320 (10)0.52393 (19)0.01713 (19)
H6A0.91940.62010.40720.021*
C70.89365 (5)0.48741 (8)0.76077 (17)0.01413 (18)
H7A0.89440.45000.89700.017*
C80.81221 (5)0.33104 (9)0.65972 (16)0.01283 (17)
C90.78245 (5)0.30394 (9)0.85792 (16)0.01439 (18)
H9A0.79150.35720.97500.017*
C100.73949 (5)0.19880 (9)0.88339 (16)0.01468 (17)
H10A0.71900.18111.01760.018*
C110.72652 (5)0.11939 (8)0.71249 (17)0.01325 (17)
C120.75683 (6)0.14583 (9)0.51485 (17)0.01527 (18)
H12A0.74890.09130.39880.018*
C130.79848 (5)0.25179 (9)0.48866 (16)0.01442 (17)
H13A0.81780.27070.35340.017*
C141.08402 (6)0.95958 (10)0.4482 (2)0.0215 (2)
H14A1.03830.99140.39040.026*
H14B1.10370.89750.34820.026*
C151.13632 (6)1.06515 (11)0.4787 (3)0.0285 (3)
H15A1.14481.10650.34270.043*
H15B1.18161.03230.53350.043*
H15C1.11651.12530.57950.043*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0213 (3)0.0180 (3)0.0234 (4)0.0072 (3)0.0018 (3)0.0007 (3)
O20.0230 (3)0.0138 (3)0.0131 (3)0.0056 (2)0.0018 (3)0.0011 (3)
N10.0156 (3)0.0116 (3)0.0138 (4)0.0003 (3)0.0002 (3)0.0000 (3)
C10.0144 (4)0.0133 (3)0.0148 (4)0.0003 (3)0.0007 (3)0.0011 (3)
C20.0177 (4)0.0183 (4)0.0146 (4)0.0008 (3)0.0029 (4)0.0003 (4)
C30.0174 (4)0.0193 (4)0.0176 (5)0.0023 (3)0.0036 (4)0.0023 (4)
C40.0146 (4)0.0140 (4)0.0193 (5)0.0013 (3)0.0018 (4)0.0007 (4)
C50.0199 (4)0.0175 (4)0.0162 (5)0.0045 (3)0.0025 (4)0.0009 (4)
C60.0188 (4)0.0176 (4)0.0150 (4)0.0044 (3)0.0017 (4)0.0002 (4)
C70.0153 (4)0.0132 (4)0.0139 (4)0.0001 (3)0.0000 (3)0.0002 (3)
C80.0144 (3)0.0114 (3)0.0126 (4)0.0002 (3)0.0005 (3)0.0001 (3)
C90.0184 (4)0.0128 (4)0.0119 (4)0.0005 (3)0.0006 (3)0.0015 (3)
C100.0192 (4)0.0137 (4)0.0111 (4)0.0010 (3)0.0012 (4)0.0007 (3)
C110.0161 (4)0.0113 (3)0.0123 (4)0.0001 (3)0.0005 (3)0.0001 (3)
C120.0196 (4)0.0143 (4)0.0119 (4)0.0018 (3)0.0011 (4)0.0015 (3)
C130.0181 (4)0.0146 (4)0.0106 (4)0.0011 (3)0.0009 (4)0.0010 (3)
C140.0199 (4)0.0176 (4)0.0269 (6)0.0038 (3)0.0014 (4)0.0044 (4)
C150.0236 (5)0.0201 (5)0.0420 (8)0.0071 (4)0.0000 (5)0.0019 (5)
Geometric parameters (Å, º) top
O1—C41.3605 (11)C7—H7A0.9500
O1—C141.4412 (16)C8—C131.3996 (14)
O2—C111.3581 (11)C8—C91.4009 (14)
O2—H1O20.83 (3)C9—C101.3951 (13)
N1—C71.2867 (13)C9—H9A0.9500
N1—C81.4228 (12)C10—C111.3973 (14)
C1—C21.4008 (15)C10—H10A0.9500
C1—C61.4026 (16)C11—C121.4004 (15)
C1—C71.4643 (13)C12—C131.3887 (13)
C2—C31.3898 (14)C12—H12A0.9500
C2—H2A0.9500C13—H13A0.9500
C3—C41.3972 (16)C14—C151.5094 (15)
C3—H3A0.9500C14—H14A0.9900
C4—C51.3970 (15)C14—H14B0.9900
C5—C61.3906 (14)C15—H15A0.9800
C5—H5A0.9500C15—H15B0.9800
C6—H6A0.9500C15—H15C0.9800
C4—O1—C14117.86 (9)C10—C9—C8119.99 (9)
C11—O2—H1O2112.7 (15)C10—C9—H9A120.0
C7—N1—C8120.62 (9)C8—C9—H9A120.0
C2—C1—C6118.43 (9)C9—C10—C11120.33 (9)
C2—C1—C7118.72 (10)C9—C10—H10A119.8
C6—C1—C7122.83 (9)C11—C10—H10A119.8
C3—C2—C1120.85 (11)O2—C11—C10123.06 (9)
C3—C2—H2A119.6O2—C11—C12117.25 (9)
C1—C2—H2A119.6C10—C11—C12119.68 (9)
C2—C3—C4120.00 (10)C13—C12—C11119.95 (9)
C2—C3—H3A120.0C13—C12—H12A120.0
C4—C3—H3A120.0C11—C12—H12A120.0
O1—C4—C5124.52 (10)C12—C13—C8120.62 (9)
O1—C4—C3115.52 (9)C12—C13—H13A119.7
C5—C4—C3119.96 (9)C8—C13—H13A119.7
C6—C5—C4119.59 (10)O1—C14—C15107.10 (11)
C6—C5—H5A120.2O1—C14—H14A110.3
C4—C5—H5A120.2C15—C14—H14A110.3
C5—C6—C1121.18 (10)O1—C14—H14B110.3
C5—C6—H6A119.4C15—C14—H14B110.3
C1—C6—H6A119.4H14A—C14—H14B108.5
N1—C7—C1122.74 (9)C14—C15—H15A109.5
N1—C7—H7A118.6C14—C15—H15B109.5
C1—C7—H7A118.6H15A—C15—H15B109.5
C13—C8—C9119.41 (9)C14—C15—H15C109.5
C13—C8—N1116.65 (9)H15A—C15—H15C109.5
C9—C8—N1123.87 (9)H15B—C15—H15C109.5
C6—C1—C2—C30.01 (15)C6—C1—C7—N15.42 (15)
C7—C1—C2—C3178.24 (9)C7—N1—C8—C13150.56 (9)
C1—C2—C3—C40.20 (15)C7—N1—C8—C932.46 (13)
C14—O1—C4—C52.99 (14)C13—C8—C9—C100.07 (14)
C14—O1—C4—C3177.23 (9)N1—C8—C9—C10176.84 (9)
C2—C3—C4—O1179.72 (9)C8—C9—C10—C110.67 (14)
C2—C3—C4—C50.48 (15)C9—C10—C11—O2178.92 (9)
O1—C4—C5—C6179.64 (9)C9—C10—C11—C120.06 (15)
C3—C4—C5—C60.58 (16)O2—C11—C12—C13177.76 (9)
C4—C5—C6—C10.40 (16)C10—C11—C12—C131.16 (15)
C2—C1—C6—C50.12 (15)C11—C12—C13—C81.78 (15)
C7—C1—C6—C5178.27 (9)C9—C8—C13—C121.16 (14)
C8—N1—C7—C1179.23 (8)N1—C8—C13—C12178.29 (9)
C2—C1—C7—N1176.43 (9)C4—O1—C14—C15179.08 (9)
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the C8–C13 ring.
D—H···AD—HH···AD···AD—H···A
O2—H1O2···N1i0.83 (2)1.87 (2)2.6971 (12)172 (2)
C6—H6A···O2ii0.952.513.3956 (14)156
C9—H9A···O2iii0.952.383.3229 (13)171
C14—H14B···Cg1iv0.992.903.7668 (12)147
Symmetry codes: (i) x+3/2, y1/2, z+1/2; (ii) x+3/2, y+1/2, z1/2; (iii) x+3/2, y+1/2, z+1/2; (iv) x+2, y+1, z1/2.

Experimental details

Crystal data
Chemical formulaC15H15NO2
Mr241.28
Crystal system, space groupOrthorhombic, Pna21
Temperature (K)100
a, b, c (Å)18.6882 (11), 10.7420 (6), 6.3186 (4)
V3)1268.45 (13)
Z4
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.59 × 0.27 × 0.25
Data collection
DiffractometerBruker SMART APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.952, 0.979
No. of measured, independent and
observed [I > 2σ(I)] reflections
16922, 2382, 2319
Rint0.025
(sin θ/λ)max1)0.745
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.086, 1.10
No. of reflections2382
No. of parameters168
No. of restraints1
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.35, 0.19

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the C8–C13 ring.
D—H···AD—HH···AD···AD—H···A
O2—H1O2···N1i0.83 (2)1.87 (2)2.6971 (12)172 (2)
C6—H6A···O2ii0.952.513.3956 (14)156
C9—H9A···O2iii0.952.383.3229 (13)171
C14—H14B···Cg1iv0.992.903.7668 (12)147
Symmetry codes: (i) x+3/2, y1/2, z+1/2; (ii) x+3/2, y+1/2, z1/2; (iii) x+3/2, y+1/2, z+1/2; (iv) x+2, y+1, z1/2.
 

Footnotes

Thomson Reuters ResearcherID: A-5085-2009.

§Additional correspondence author, e-mail: hfun@usm.my. Thomson Reuters ResearcherID: A-3561-2009.

Acknowledgements

NK thanks the Center of Excellence for Innovation in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Education, and the Graduate School, Prince of Songkla University, for financial support. The authors extend their appreciation to the Malaysian Government and Universiti Sains Malaysia for APEX DE2012 grant No. 1002/PFIZIK/910323, and the Deanship of Scientific Research and the Research Center, College of Pharmacy, King Saud University.

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Volume 69| Part 6| June 2013| Pages o903-o904
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