3-Acetyl-1-(3-methyl­phen­yl)-5-phenyl-1H-pyrazole-4-carbonitrile

Abdel-Aziz, H.A.; Al-Obaid, A.-R.M.; Ghabbour, H.A.; Hemamalini, M.; Fun, H.-K.

doi:10.1107/S160053681200181X

organic compounds

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ISSN: 2056-9890

Volume 68| Part 2| February 2012| Pages o485-o486

doi:10.1107/S160053681200181X

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3-Acetyl-1-(3-methylphenyl)-5-phenyl-1H-pyrazole-4-carbonitrile

Hatem A. Abdel-Aziz,^a Abdul-Rahman M. Al-Obaid,^a Hazem A. Ghabbour,^a Madhukar Hemamalini ^b and Hoong-Kun Fun ^b ^*‡

^aDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia, and ^bX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
^*Correspondence e-mail: hkfun@usm.my

(Received 13 January 2012; accepted 15 January 2012; online 21 January 2012)

In the title compound, C₁₉H₁₅N₃O, the central pyrazole ring makes dihedral angles of 35.52 (12) and 62.21 (11)° with the attached phenyl and methyl-substituted phenyl rings, respectively. The corresponding angle between the phenyl and methyl-substituted phenyl rings is 62.90 (11)°. In the crystal, molecules are connected by weak C—H⋯O hydrogen bonds, forming supramolecular chains propagating along the a-axis direction.

Related literature

For details and applications of pyrazole compounds, see: Kovbasyuk et al. (2004 ); Sachse et al. (2008 ); De Geest et al. (2007 ); Roy et al. (2008 ). For related structures, see: Fun et al. (2011a ,b ,c ). For further synthetic details, see: Nassar et al. (2011 ).

Experimental

Crystal data

C₁₉H₁₅N₃O
M_r = 301.34
Monoclinic, P 2₁ /c
a = 11.8544 (8) Å
b = 7.6731 (6) Å
c = 17.4048 (15) Å
β = 96.202 (6)°
V = 1573.9 (2) Å³
Z = 4
Cu Kα radiation
μ = 0.65 mm⁻¹
T = 296 K
0.55 × 0.21 × 0.16 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.717, T_max = 0.902
8352 measured reflections
2776 independent reflections
1804 reflections with I > 2σ(I)
R_int = 0.091

Refinement

R[F² > 2σ(F²)] = 0.059
wR(F²) = 0.227
S = 1.05
2776 reflections
209 parameters
H-atom parameters constrained
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.37 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3A⋯O1ⁱ	0.93	2.56	3.444 (3)	160
Symmetry code: (i) x-1, y, z.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681200181X/hb6607sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681200181X/hb6607Isup2.hkl

Supporting information file. DOI: 10.1107/S160053681200181X/hb6607Isup3.cml

checkCIF report

Comment top

Pyrazole-based ligands have attracted considerable attention due to their bridging nature and possibility for easy functionalization with various additional donor groups (Kovbasyuk et al., 2004; Sachse et al., 2008). In particular, azomethine-functionalized pyrazoles have been used extensively as ligands in the field of coordination chemistry and catalysis (De Geest et al., 2007; Roy et al., 2008). The crystal structures of 4-(1,3-Diphenyl-4,5-dihydro-1H-pyrazol-5-yl)-1,3-diphenyl- 1H-pyrazole, 3-Methyl-5-oxo-4-(2-phenylhydrazinylidene)-4,5- dihydro-1H-pyrazole-1-carbothioamide and (2E)-3-(1,3- Diphenyl-1H-pyrazol-4-yl)-1-phenylprop-2-en-1-one (Fun et al., 2011a,b,c) have been reported from our laboratory. In continuation of our studies of pyrazole compounds, the crystal structure determination of the title compound has been undertaken.

The asymmetric unit of the title compound is shown in Fig. 1. The central pyrazole (N1,N2/C9–C11) ring makes dihedral angles of 35.52 (12) and 62.21 (11)° with the attached phenyl (C12–C17) and methyl substituted pheny (C1–C6) rings. The corresponding angle between the phenyl (C12–C17) and methyl substituted (C1–C6) phenyl rings is 62.90 (11)°.

In the crystal structure (Fig. 2), molecules are connected by weak intermolecular C—H···O (Table 1) hydrogen bonds, forming supramolecular chains propagating along the a-axis direction.

Related literature top

For details and applications of pyrazole compounds, see: Kovbasyuk et al. (2004); Sachse et al. (2008); De Geest et al. (2007); Roy et al. (2008). For related structures, see: Fun et al. (2011a,b,c). For further synthetic details, see: Nassar et al. (2011).

Experimental top

The title compound was prepared according to the reported method (Nassar et al., 2011). Colourless blocks were obtained by slowly evaporating from ethanol at room temperature.

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

	Fig. 1. The asymmetric unit of the title compound, showing 50% probability displacement ellipsoids.
	Fig. 2. The crystal packing of title compound (I).

3-Acetyl-1-(3-methylphenyl)-5-phenyl-1H-pyrazole-4-carbonitrile top

Crystal data top

C₁₉H₁₅N₃O	F(000) = 632
M_r = 301.34	D_x = 1.272 Mg m⁻³
Monoclinic, P2₁/c	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2ybc	Cell parameters from 1651 reflections
a = 11.8544 (8) Å	θ = 6.3–66.5°
b = 7.6731 (6) Å	µ = 0.65 mm⁻¹
c = 17.4048 (15) Å	T = 296 K
β = 96.202 (6)°	Block, colourless
V = 1573.9 (2) Å³	0.55 × 0.21 × 0.16 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD diffractometer	2776 independent reflections
Radiation source: fine-focus sealed tube	1804 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.091
ϕ and ω scans	θ_max = 67.4°, θ_min = 3.8°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −11→14
T_min = 0.717, T_max = 0.902	k = −9→8
8352 measured reflections	l = −19→20

Refinement top

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)] = 0.059	H-atom parameters constrained
wR(F²) = 0.227	w = 1/[σ²(F_o²) + (0.1264P)² + 0.0573P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
2776 reflections	Δρ_max = 0.27 e Å⁻³
209 parameters	Δρ_min = −0.37 e Å⁻³
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0042 (13)

Crystal data top

C₁₉H₁₅N₃O	V = 1573.9 (2) Å³
M_r = 301.34	Z = 4
Monoclinic, P2₁/c	Cu Kα radiation
a = 11.8544 (8) Å	µ = 0.65 mm⁻¹
b = 7.6731 (6) Å	T = 296 K
c = 17.4048 (15) Å	0.55 × 0.21 × 0.16 mm
β = 96.202 (6)°

Data collection top

Bruker SMART APEXII CCD diffractometer	2776 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	1804 reflections with I > 2σ(I)
T_min = 0.717, T_max = 0.902	R_int = 0.091
8352 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.059	0 restraints
wR(F²) = 0.227	H-atom parameters constrained
S = 1.05	Δρ_max = 0.27 e Å⁻³
2776 reflections	Δρ_min = −0.37 e Å⁻³
209 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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

	x	y	z	U_iso*/U_eq
C1	0.18649 (19)	−0.0026 (3)	0.85181 (12)	0.0503 (7)
H1A	0.2331	−0.0955	0.8688	0.060*
C2	0.0758 (2)	0.0011 (3)	0.86879 (13)	0.0550 (7)
C3	0.0088 (2)	0.1432 (3)	0.84253 (14)	0.0586 (7)
H3A	−0.0662	0.1492	0.8534	0.070*
C4	0.0527 (2)	0.2746 (3)	0.80077 (14)	0.0590 (7)
H4A	0.0064	0.3677	0.7837	0.071*
C5	0.1629 (2)	0.2711 (3)	0.78384 (13)	0.0538 (6)
H5A	0.1924	0.3604	0.7559	0.065*
C6	0.22883 (19)	0.1295 (3)	0.80997 (12)	0.0461 (6)
N1	0.34545 (16)	0.1197 (2)	0.79402 (11)	0.0489 (6)
N2	0.42757 (17)	0.1217 (2)	0.85538 (11)	0.0523 (6)
C9	0.5249 (2)	0.1171 (3)	0.82443 (14)	0.0482 (6)
C10	0.5062 (2)	0.1118 (3)	0.74350 (13)	0.0496 (7)
C11	0.38934 (19)	0.1128 (2)	0.72492 (13)	0.0458 (6)
C12	0.32137 (19)	0.1023 (3)	0.64932 (13)	0.0480 (6)
C13	0.2211 (2)	0.0089 (3)	0.63772 (13)	0.0521 (6)
H13A	0.1937	−0.0474	0.6792	0.062*
C14	0.1610 (2)	−0.0016 (3)	0.56516 (14)	0.0615 (7)
H14A	0.0931	−0.0634	0.5583	0.074*
C15	0.2016 (2)	0.0791 (4)	0.50341 (16)	0.0684 (8)
H15A	0.1609	0.0724	0.4547	0.082*
C16	0.3012 (2)	0.1689 (3)	0.51313 (15)	0.0687 (8)
H16A	0.3289	0.2213	0.4708	0.082*
C17	0.3613 (2)	0.1829 (3)	0.58552 (13)	0.0588 (7)
H17A	0.4286	0.2462	0.5918	0.071*
C18	0.5895 (2)	0.1047 (3)	0.69062 (17)	0.0593 (7)
N4	0.6559 (2)	0.1033 (3)	0.64697 (16)	0.0835 (8)
C20	0.6343 (2)	0.1168 (3)	0.87444 (16)	0.0569 (7)
O1	0.72089 (16)	0.0876 (3)	0.84499 (12)	0.0754 (6)
C23	0.0279 (3)	−0.1453 (4)	0.91259 (19)	0.0857 (10)
H23A	0.0861	−0.2303	0.9263	0.129*
H23D	−0.0337	−0.1989	0.8808	0.129*
H23B	0.0008	−0.1002	0.9587	0.129*
C21	0.6332 (2)	0.1535 (4)	0.95825 (15)	0.0720 (8)
H21A	0.7093	0.1493	0.9834	0.108*
H21B	0.5877	0.0677	0.9806	0.108*
H21C	0.6018	0.2672	0.9648	0.108*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0445 (16)	0.0626 (13)	0.0437 (14)	0.0026 (10)	0.0046 (11)	0.0018 (9)
C2	0.0493 (16)	0.0690 (14)	0.0472 (13)	−0.0093 (11)	0.0078 (11)	−0.0001 (10)
C3	0.0421 (15)	0.0816 (16)	0.0528 (15)	0.0036 (11)	0.0086 (12)	−0.0018 (11)
C4	0.0484 (16)	0.0692 (14)	0.0592 (16)	0.0083 (12)	0.0045 (12)	0.0040 (11)
C5	0.0506 (15)	0.0614 (13)	0.0499 (14)	0.0022 (11)	0.0078 (11)	0.0052 (10)
C6	0.0397 (15)	0.0631 (12)	0.0358 (13)	0.0000 (9)	0.0048 (10)	−0.0027 (9)
N1	0.0401 (12)	0.0642 (11)	0.0426 (12)	0.0001 (8)	0.0054 (9)	−0.0009 (8)
N2	0.0423 (13)	0.0694 (12)	0.0443 (12)	−0.0013 (9)	0.0009 (10)	−0.0006 (8)
C9	0.0412 (15)	0.0551 (12)	0.0491 (15)	−0.0021 (9)	0.0083 (11)	−0.0004 (9)
C10	0.0449 (15)	0.0538 (12)	0.0515 (15)	0.0006 (9)	0.0112 (11)	−0.0009 (9)
C11	0.0479 (16)	0.0495 (11)	0.0413 (14)	−0.0013 (9)	0.0105 (11)	0.0015 (8)
C12	0.0470 (15)	0.0528 (12)	0.0452 (14)	0.0058 (9)	0.0100 (11)	−0.0015 (8)
C13	0.0524 (15)	0.0598 (13)	0.0446 (13)	0.0006 (11)	0.0080 (11)	−0.0033 (9)
C14	0.0573 (17)	0.0707 (15)	0.0553 (15)	0.0001 (12)	0.0007 (13)	−0.0077 (12)
C15	0.074 (2)	0.0811 (17)	0.0479 (16)	0.0099 (14)	−0.0039 (14)	−0.0015 (12)
C16	0.083 (2)	0.0761 (16)	0.0487 (16)	0.0035 (14)	0.0133 (14)	0.0132 (12)
C17	0.0654 (17)	0.0610 (14)	0.0510 (15)	−0.0043 (11)	0.0112 (12)	0.0052 (10)
C18	0.0510 (18)	0.0670 (15)	0.0610 (18)	−0.0022 (11)	0.0110 (14)	−0.0011 (11)
N4	0.0713 (18)	0.1056 (18)	0.0788 (19)	0.0031 (13)	0.0314 (15)	0.0018 (13)
C20	0.0425 (16)	0.0623 (14)	0.0655 (17)	−0.0066 (11)	0.0044 (13)	0.0035 (11)
O1	0.0429 (13)	0.0973 (14)	0.0857 (15)	−0.0028 (9)	0.0053 (11)	−0.0070 (10)
C23	0.077 (2)	0.096 (2)	0.088 (2)	−0.0160 (16)	0.0272 (18)	0.0198 (16)
C21	0.0598 (17)	0.0930 (19)	0.0603 (17)	−0.0084 (14)	−0.0071 (14)	−0.0044 (14)

Geometric parameters (Å, º) top

C1—C6	1.375 (3)	C12—C13	1.384 (3)
C1—C2	1.376 (3)	C12—C17	1.398 (3)
C1—H1A	0.9300	C13—C14	1.384 (3)
C2—C3	1.396 (3)	C13—H13A	0.9300
C2—C23	1.503 (4)	C14—C15	1.372 (4)
C3—C4	1.377 (3)	C14—H14A	0.9300
C3—H3A	0.9300	C15—C16	1.362 (4)
C4—C5	1.370 (3)	C15—H15A	0.9300
C4—H4A	0.9300	C16—C17	1.383 (4)
C5—C6	1.386 (3)	C16—H16A	0.9300
C5—H5A	0.9300	C17—H17A	0.9300
C6—N1	1.441 (3)	C18—N4	1.151 (3)
N1—C11	1.362 (3)	C20—O1	1.217 (3)
N1—N2	1.365 (3)	C20—C21	1.487 (4)
N2—C9	1.325 (3)	C23—H23A	0.9600
C9—C10	1.403 (3)	C23—H23D	0.9600
C9—C20	1.482 (3)	C23—H23B	0.9600
C10—C11	1.388 (3)	C21—H21A	0.9600
C10—C18	1.422 (4)	C21—H21B	0.9600
C11—C12	1.469 (3)	C21—H21C	0.9600

C6—C1—C2	120.6 (2)	C17—C12—C11	119.2 (2)
C6—C1—H1A	119.7	C14—C13—C12	120.8 (2)
C2—C1—H1A	119.7	C14—C13—H13A	119.6
C1—C2—C3	117.9 (2)	C12—C13—H13A	119.6
C1—C2—C23	121.0 (2)	C15—C14—C13	120.0 (2)
C3—C2—C23	121.2 (2)	C15—C14—H14A	120.0
C4—C3—C2	120.7 (2)	C13—C14—H14A	120.0
C4—C3—H3A	119.6	C16—C15—C14	120.3 (2)
C2—C3—H3A	119.6	C16—C15—H15A	119.9
C5—C4—C3	121.5 (2)	C14—C15—H15A	119.9
C5—C4—H4A	119.3	C15—C16—C17	120.5 (2)
C3—C4—H4A	119.3	C15—C16—H16A	119.8
C4—C5—C6	117.5 (2)	C17—C16—H16A	119.8
C4—C5—H5A	121.3	C16—C17—C12	120.2 (2)
C6—C5—H5A	121.3	C16—C17—H17A	119.9
C1—C6—C5	121.8 (2)	C12—C17—H17A	119.9
C1—C6—N1	118.43 (19)	N4—C18—C10	178.1 (3)
C5—C6—N1	119.8 (2)	O1—C20—C9	118.5 (2)
C11—N1—N2	112.52 (19)	O1—C20—C21	123.0 (2)
C11—N1—C6	129.64 (18)	C9—C20—C21	118.4 (3)
N2—N1—C6	117.81 (19)	C2—C23—H23A	109.5
C9—N2—N1	105.08 (19)	C2—C23—H23D	109.5
N2—C9—C10	111.1 (2)	H23A—C23—H23D	109.5
N2—C9—C20	120.4 (2)	C2—C23—H23B	109.5
C10—C9—C20	128.5 (3)	H23A—C23—H23B	109.5
C11—C10—C9	106.2 (2)	H23D—C23—H23B	109.5
C11—C10—C18	126.5 (2)	C20—C21—H21A	109.5
C9—C10—C18	127.3 (2)	C20—C21—H21B	109.5
N1—C11—C10	105.15 (19)	H21A—C21—H21B	109.5
N1—C11—C12	124.6 (2)	C20—C21—H21C	109.5
C10—C11—C12	130.2 (2)	H21A—C21—H21C	109.5
C13—C12—C17	118.2 (2)	H21B—C21—H21C	109.5
C13—C12—C11	122.6 (2)

C6—C1—C2—C3	−0.3 (3)	C6—N1—C11—C10	177.65 (19)
C6—C1—C2—C23	178.3 (2)	N2—N1—C11—C12	177.50 (17)
C1—C2—C3—C4	0.2 (3)	C6—N1—C11—C12	−4.4 (3)
C23—C2—C3—C4	−178.4 (3)	C9—C10—C11—N1	0.4 (2)
C2—C3—C4—C5	−0.3 (4)	C18—C10—C11—N1	179.7 (2)
C3—C4—C5—C6	0.4 (4)	C9—C10—C11—C12	−177.45 (19)
C2—C1—C6—C5	0.4 (3)	C18—C10—C11—C12	1.9 (3)
C2—C1—C6—N1	179.76 (18)	N1—C11—C12—C13	−36.0 (3)
C4—C5—C6—C1	−0.5 (3)	C10—C11—C12—C13	141.5 (2)
C4—C5—C6—N1	−179.78 (19)	N1—C11—C12—C17	146.9 (2)
C1—C6—N1—C11	119.3 (2)	C10—C11—C12—C17	−35.6 (3)
C5—C6—N1—C11	−61.3 (3)	C17—C12—C13—C14	−1.1 (3)
C1—C6—N1—N2	−62.6 (2)	C11—C12—C13—C14	−178.3 (2)
C5—C6—N1—N2	116.7 (2)	C12—C13—C14—C15	0.9 (4)
C11—N1—N2—C9	0.4 (2)	C13—C14—C15—C16	0.3 (4)
C6—N1—N2—C9	−177.99 (17)	C14—C15—C16—C17	−1.3 (4)
N1—N2—C9—C10	−0.1 (2)	C15—C16—C17—C12	1.1 (4)
N1—N2—C9—C20	−179.71 (19)	C13—C12—C17—C16	0.2 (3)
N2—C9—C10—C11	−0.2 (2)	C11—C12—C17—C16	177.4 (2)
C20—C9—C10—C11	179.4 (2)	N2—C9—C20—O1	169.6 (2)
N2—C9—C10—C18	−179.5 (2)	C10—C9—C20—O1	−9.9 (3)
C20—C9—C10—C18	0.0 (4)	N2—C9—C20—C21	−10.8 (3)
N2—N1—C11—C10	−0.5 (2)	C10—C9—C20—C21	169.7 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3A···O1ⁱ	0.93	2.56	3.444 (3)	160

Symmetry code: (i) x−1, y, z.

Experimental details

Crystal data
Chemical formula	C₁₉H₁₅N₃O
M_r	301.34
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	11.8544 (8), 7.6731 (6), 17.4048 (15)
β (°)	96.202 (6)
V (Å³)	1573.9 (2)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.65
Crystal size (mm)	0.55 × 0.21 × 0.16

Data collection
Diffractometer	Bruker SMART APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.717, 0.902
No. of measured, independent and observed [I > 2σ(I)] reflections	8352, 2776, 1804
R_int	0.091
(sin θ/λ)_max (Å⁻¹)	0.599

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.059, 0.227, 1.05
No. of reflections	2776
No. of parameters	209
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.27, −0.37

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3A···O1ⁱ	0.93	2.56	3.444 (3)	160

Symmetry code: (i) x−1, y, z.

Footnotes

‡Visiting Professor, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia. Thomson Reuters ResearcherID: A-3561-2009.

Acknowledgements

HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University Grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship. HAA, AMA and HAG thank Universiti Sains Malaysia and King Saud University for supporting this study.

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