4-Amino-3-[(4-methoxy­phen­yl)amino­meth­yl]-1H-1,2,4-triazole-5(4H)-thione

Fun, H.-K.; Yeap, C.S.; Malladi, S.; Padaki, M.; Isloor, A.M.

doi:10.1107/S1600536809032607

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 9| September 2009| Page o2213

doi:10.1107/S1600536809032607

Open

access

4-Amino-3-[(4-methoxyphenyl)aminomethyl]-1H-1,2,4-triazole-5(4H)-thione

Hoong-Kun Fun,^a ^*‡ Chin Sing Yeap,^a § Shridhar Malladi,^b Mahesh Padaki ^b and Arun M. Isloor ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bDepartment of Chemistry, National Institute of Technology-Karnataka, Surathkal, Mangalore 575 025, India
^*Correspondence e-mail: hkfun@usm.my

(Received 17 August 2009; accepted 17 August 2009; online 22 August 2009)

The molecule of the title compound, C₁₀H₁₃N₅OS, is approximately planar, the dihedral angle between the triazole and benzene rings being 4.53 (10)°. The amino group adopts a pyramidal configuration. In the crystal structure, molecules are linked into two-dimensional networks parallel to (001) by intermolecular N—H⋯S and N—H⋯N hydrogen bonds. In addition, an S⋯S short contact of 3.3435 (7) Å is observed.

Related literature

For the pharmacological applications of 1,2,4-triazole derivatives, see: Amir et al. (2008 ); Isloor et al. (2009 ); Krzysztof et al. (2008 ); Kuş et al. (2008 ); Padmavathi et al. (2008 ). For the preparation, see: Holla & Udupa (1992 ). For related structures, see: Fun et al. (2009a ,b ). For the stability of the temperature controller used for data collection, see: Cosier & Glazer (1986 ).

Experimental

Crystal data

C₁₀H₁₃N₅OS
M_r = 251.31
Monoclinic, C 2
a = 11.5142 (2) Å
b = 5.8804 (1) Å
c = 16.6891 (3) Å
β = 95.292 (1)°
V = 1125.17 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.28 mm⁻¹
T = 100 K
0.33 × 0.18 × 0.02 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.913, T_max = 0.994
5827 measured reflections
2365 independent reflections
2126 reflections with I > 2σ(I)
R_int = 0.024

Refinement

R[F² > 2σ(F²)] = 0.031
wR(F²) = 0.068
S = 1.04
2365 reflections
171 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.26 e Å⁻³
Absolute structure: Flack (1983 ), 588 Friedel pairs
Flack parameter: 0.03 (7)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H1N2⋯S1ⁱ	0.84 (2)	2.55 (2)	3.3672 (18)	164 (2)
N4—H1N4⋯N5ⁱⁱ	0.82 (3)	2.60 (3)	3.410 (2)	169 (3)
N5—H1N5⋯N1ⁱⁱⁱ	0.89 (2)	2.48 (2)	3.133 (2)	130 (2)
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z]$ ; (ii) $[x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (iii) $[x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ .

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); 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/S1600536809032607/ci2889sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809032607/ci2889Isup2.hkl

checkCIF report

Comment top

1,2,4-triazole and its derivatives were reported to exhibit various pharmacological activities such as antimicrobial, analgesic, anti-inflammatory, anticancer and antioxidant properties (Amir et al., 2008; Krzysztof et al., 2008; Kuş et al., 2008; Padmavathi et al., 2008). A few derivatives of triazoles have exhibited antimicrobial activity (Isloor et al., 2009). Some of the present day drugs such as ribavirin (antiviral agent), rizatriptan (antimigraine agent), alprazolam (anxiolytic agent), fluconazole and itraconazole (antifungal agents) are the best examples for potent molecules possessing the triazole nucleus. The amino and mercapto groups of 1,2,4-triazoles serve as readily accessible nucleophilic centers for the preparation of N-bridged heterocycles. Keeping in view of the biological importance, we have synthesized the title compound and its crystal structure is reported here.

Bond lengths and angles in the title compound (Fig. 1) are comparable to those observed in related structures (Fun et al., 2009a,b). The molecule is approximately planar, with the dihedral angle between the triazole (N1/N2/C1/N3/C2) and benzene rings (C4-C9) being 4.53 (10)°.

In the crystal structure, the molecules are linked by intermolecular N2—H1N2···S1, N4—H1N4···N5 and N5—H1N5···N1 hydrogen bonds into a two-dimensional network parallel to ab plane (Fig. 2 and Table 1). In addition, a S···S(1-x, y, -z) short contact of 3.3435 (7) Å is observed.

Related literature top

For the pharmacological applications of 1,2,4-triazole derivatives, see: Amir et al. (2008); Isloor et al. (2009); Krzysztof et al. (2008); Kuş et al. (2008); Padmavathi et al. (2008). For the preparation, see: Holla & Udupa (1992). For related structures, see: Fun et al. (2009a,b). For the stability of the temperature controller used for data collection, see: Cosier & Glazer (1986).

Experimental top

2-[(4-Methoxyphenyl)amino]acetohydrazide (19.5 g, 0.1 mol) was added slowly to a solution of potassium hydroxide (8.4 g, 0.15 mol) in ethanol (150 ml). The resulting mixture was stirred well till a clear solution was obtained. Carbon disulfide (11.4 g, 0.15 mol) was added dropwise and the contents were stirred vigorously. Further stirring was continued for 24 h. The resulting mixture (Holla & Udupa, 1992) was diluted with 100 ml of ether and the precipitate formed was collected by filtration, washed with dry ether and dried at 338 K under vacuum. It was used for the next step without any purification.

A mixture of above synthesized potassium dithiocarbazinate (30.9 g, 0.1 mol), hydrazine hydrate (99%, 0.2 mol) and water (2 ml) was gently heated to boil for 30 min. Heating was continued until the evaluation of hydrogen sulfide ceases. The reaction mixture was cooled to room temperature, diluted with water (100 ml) and acidified with 2 N HCl. The solid mass that separated was collected by filtration, washed with water and dried. Recrystallization was done from ethanol (yield: 15.1 g, 67.7%; m.p. 484–486 K).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); 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 molecular structure of the title compound, with atom labels and 50% probability ellipsoids for non-H atoms.
	Fig. 2. The crystal structure of the title compound, viewed down the b axis, showing two-dimensional networks parallel to ab plane. Intermolecular hydrogen bonds are shown as dashed lines.

4-Amino-3-[(4-methoxyphenyl)aminomethyl]-1H-1,2,4-triazole- 5(4H)-thione top

Crystal data top

C₁₀H₁₃N₅OS	F(000) = 528
M_r = 251.31	D_x = 1.484 Mg m⁻³
Monoclinic, C2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C 2y	Cell parameters from 2961 reflections
a = 11.5142 (2) Å	θ = 3.6–32.2°
b = 5.8804 (1) Å	µ = 0.28 mm⁻¹
c = 16.6891 (3) Å	T = 100 K
β = 95.292 (1)°	Plate, colourless
V = 1125.17 (3) Å³	0.33 × 0.18 × 0.02 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2365 independent reflections
Radiation source: fine-focus sealed tube	2126 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.024
ϕ and ω scans	θ_max = 30.0°, θ_min = 3.6°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −15→16
T_min = 0.913, T_max = 0.994	k = −8→5
5827 measured reflections	l = −23→23

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)] = 0.031	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.068	w = 1/[σ²(F_o²) + (0.0277P)² + 0.6764P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.001
2365 reflections	Δρ_max = 0.33 e Å⁻³
171 parameters	Δρ_min = −0.26 e Å⁻³
1 restraint	Absolute structure: Flack (1983), 588 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.03 (7)

Crystal data top

C₁₀H₁₃N₅OS	V = 1125.17 (3) Å³
M_r = 251.31	Z = 4
Monoclinic, C2	Mo Kα radiation
a = 11.5142 (2) Å	µ = 0.28 mm⁻¹
b = 5.8804 (1) Å	T = 100 K
c = 16.6891 (3) Å	0.33 × 0.18 × 0.02 mm
β = 95.292 (1)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2365 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2126 reflections with I > 2σ(I)
T_min = 0.913, T_max = 0.994	R_int = 0.024
5827 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.031	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.068	Δρ_max = 0.33 e Å⁻³
S = 1.04	Δρ_min = −0.26 e Å⁻³
2365 reflections	Absolute structure: Flack (1983), 588 Friedel pairs
171 parameters	Absolute structure parameter: 0.03 (7)
1 restraint

Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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

	x	y	z	U_iso*/U_eq
S1	0.37035 (4)	0.34412 (9)	0.03759 (3)	0.01571 (11)
O1	−0.26796 (11)	1.2919 (3)	0.42305 (8)	0.0248 (4)
N1	0.07536 (13)	0.3929 (3)	0.13658 (9)	0.0171 (4)
N2	0.15394 (14)	0.2872 (3)	0.09067 (10)	0.0164 (4)
N3	0.23563 (13)	0.5947 (3)	0.13167 (9)	0.0136 (3)
N4	−0.02128 (14)	0.6826 (3)	0.24608 (10)	0.0167 (4)
N5	0.30984 (14)	0.7845 (3)	0.14247 (10)	0.0171 (4)
C1	0.25184 (15)	0.4074 (3)	0.08580 (11)	0.0144 (4)
C2	0.12844 (15)	0.5803 (4)	0.16083 (11)	0.0138 (4)
C3	0.08129 (16)	0.7617 (4)	0.21027 (12)	0.0158 (4)
H3A	0.1404	0.8072	0.2524	0.019*
H3B	0.0613	0.8933	0.1768	0.019*
C4	−0.08548 (14)	0.8413 (4)	0.28707 (10)	0.0146 (3)
C5	−0.04122 (16)	1.0556 (4)	0.31036 (12)	0.0174 (4)
H5A	0.0307	1.1019	0.2950	0.021*
C6	−0.10392 (16)	1.1985 (4)	0.35610 (12)	0.0187 (4)
H6A	−0.0732	1.3398	0.3715	0.022*
C7	−0.21184 (16)	1.1350 (4)	0.37941 (11)	0.0168 (4)
C8	−0.25711 (16)	0.9225 (4)	0.35578 (11)	0.0174 (4)
H8A	−0.3295	0.8776	0.3708	0.021*
C9	−0.19487 (15)	0.7792 (4)	0.31039 (11)	0.0163 (4)
H9A	−0.2261	0.6384	0.2949	0.020*
C10	−0.37125 (17)	1.2205 (4)	0.45705 (12)	0.0219 (5)
H10A	−0.3982	1.3406	0.4896	0.033*
H10B	−0.3545	1.0881	0.4897	0.033*
H10C	−0.4305	1.1848	0.4147	0.033*
H1N2	0.1335 (18)	0.175 (4)	0.0617 (13)	0.016 (6)*
H1N4	−0.063 (2)	0.601 (5)	0.2156 (15)	0.032 (7)*
H1N5	0.381 (2)	0.728 (5)	0.1550 (16)	0.047 (8)*
H2N5	0.3141 (19)	0.845 (6)	0.0921 (15)	0.042 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.01344 (18)	0.0157 (2)	0.0184 (2)	0.0019 (2)	0.00344 (15)	−0.0002 (2)
O1	0.0220 (7)	0.0201 (9)	0.0342 (8)	−0.0015 (6)	0.0123 (6)	−0.0096 (7)
N1	0.0157 (7)	0.0161 (10)	0.0201 (8)	−0.0007 (7)	0.0052 (6)	0.0000 (7)
N2	0.0186 (7)	0.0117 (9)	0.0197 (8)	−0.0021 (6)	0.0050 (6)	−0.0030 (7)
N3	0.0126 (7)	0.0149 (9)	0.0135 (7)	−0.0008 (6)	0.0015 (6)	−0.0003 (7)
N4	0.0150 (8)	0.0149 (9)	0.0208 (9)	−0.0039 (7)	0.0051 (7)	−0.0033 (7)
N5	0.0142 (7)	0.0148 (9)	0.0220 (9)	−0.0050 (6)	0.0006 (6)	−0.0019 (7)
C1	0.0143 (8)	0.0155 (10)	0.0135 (8)	0.0025 (7)	0.0011 (7)	0.0001 (7)
C2	0.0132 (8)	0.0156 (10)	0.0126 (9)	0.0022 (7)	0.0015 (7)	0.0029 (8)
C3	0.0151 (8)	0.0140 (10)	0.0183 (9)	−0.0012 (7)	0.0020 (7)	0.0006 (8)
C4	0.0153 (7)	0.0154 (9)	0.0132 (7)	0.0032 (9)	0.0012 (6)	0.0006 (10)
C5	0.0139 (9)	0.0176 (11)	0.0211 (10)	−0.0015 (8)	0.0043 (7)	0.0005 (8)
C6	0.0188 (9)	0.0146 (10)	0.0228 (10)	−0.0027 (8)	0.0020 (8)	−0.0037 (8)
C7	0.0174 (9)	0.0165 (10)	0.0167 (9)	0.0015 (8)	0.0030 (7)	−0.0005 (8)
C8	0.0157 (9)	0.0184 (10)	0.0187 (9)	−0.0014 (8)	0.0044 (7)	0.0013 (8)
C9	0.0163 (8)	0.0121 (10)	0.0203 (9)	−0.0024 (7)	0.0002 (7)	−0.0006 (8)
C10	0.0177 (9)	0.0258 (13)	0.0228 (10)	0.0016 (9)	0.0057 (8)	−0.0032 (9)

Geometric parameters (Å, º) top

S1—C1	1.6883 (18)	C3—H3A	0.97
O1—C7	1.373 (2)	C3—H3B	0.97
O1—C10	1.427 (2)	C4—C5	1.401 (3)
N1—C2	1.306 (3)	C4—C9	1.401 (2)
N1—N2	1.386 (2)	C5—C6	1.383 (3)
N2—C1	1.339 (2)	C5—H5A	0.93
N2—H1N2	0.84 (2)	C6—C7	1.387 (3)
N3—C1	1.364 (3)	C6—H6A	0.93
N3—C2	1.370 (2)	C7—C8	1.397 (3)
N3—N5	1.407 (2)	C8—C9	1.377 (3)
N4—C4	1.407 (3)	C8—H8A	0.93
N4—C3	1.448 (2)	C9—H9A	0.93
N4—H1N4	0.82 (3)	C10—H10A	0.96
N5—H1N5	0.89 (3)	C10—H10B	0.96
N5—H2N5	0.92 (3)	C10—H10C	0.96
C2—C3	1.482 (3)

C7—O1—C10	117.60 (17)	H3A—C3—H3B	108.1
C2—N1—N2	103.83 (15)	C5—C4—C9	118.09 (18)
C1—N2—N1	113.14 (16)	C5—C4—N4	122.53 (16)
C1—N2—H1N2	125.0 (14)	C9—C4—N4	119.3 (2)
N1—N2—H1N2	120.6 (14)	C6—C5—C4	120.33 (17)
C1—N3—C2	108.88 (16)	C6—C5—H5A	119.8
C1—N3—N5	126.84 (15)	C4—C5—H5A	119.8
C2—N3—N5	124.04 (17)	C5—C6—C7	121.20 (19)
C4—N4—C3	118.22 (18)	C5—C6—H6A	119.4
C4—N4—H1N4	112.7 (18)	C7—C6—H6A	119.4
C3—N4—H1N4	112.5 (17)	O1—C7—C6	116.46 (18)
N3—N5—H1N5	105.8 (19)	O1—C7—C8	124.69 (17)
N3—N5—H2N5	105.9 (18)	C6—C7—C8	118.83 (18)
H1N5—N5—H2N5	103 (2)	C9—C8—C7	120.19 (17)
N2—C1—N3	103.45 (15)	C9—C8—H8A	119.9
N2—C1—S1	129.38 (15)	C7—C8—H8A	119.9
N3—C1—S1	127.15 (15)	C8—C9—C4	121.4 (2)
N1—C2—N3	110.68 (18)	C8—C9—H9A	119.3
N1—C2—C3	126.50 (17)	C4—C9—H9A	119.3
N3—C2—C3	122.78 (18)	O1—C10—H10A	109.5
N4—C3—C2	110.69 (17)	O1—C10—H10B	109.5
N4—C3—H3A	109.5	H10A—C10—H10B	109.5
C2—C3—H3A	109.5	O1—C10—H10C	109.5
N4—C3—H3B	109.5	H10A—C10—H10C	109.5
C2—C3—H3B	109.5	H10B—C10—H10C	109.5

C2—N1—N2—C1	−0.9 (2)	N3—C2—C3—N4	−168.35 (17)
N1—N2—C1—N3	1.1 (2)	C3—N4—C4—C5	−14.9 (3)
N1—N2—C1—S1	179.40 (14)	C3—N4—C4—C9	169.36 (17)
C2—N3—C1—N2	−0.9 (2)	C9—C4—C5—C6	1.0 (3)
N5—N3—C1—N2	−175.43 (17)	N4—C4—C5—C6	−174.84 (19)
C2—N3—C1—S1	−179.25 (15)	C4—C5—C6—C7	−0.5 (3)
N5—N3—C1—S1	6.3 (3)	C10—O1—C7—C6	−171.73 (18)
N2—N1—C2—N3	0.2 (2)	C10—O1—C7—C8	10.0 (3)
N2—N1—C2—C3	177.94 (18)	C5—C6—C7—O1	−178.46 (18)
C1—N3—C2—N1	0.4 (2)	C5—C6—C7—C8	−0.1 (3)
N5—N3—C2—N1	175.13 (17)	O1—C7—C8—C9	178.47 (18)
C1—N3—C2—C3	−177.35 (17)	C6—C7—C8—C9	0.2 (3)
N5—N3—C2—C3	−2.7 (3)	C7—C8—C9—C4	0.2 (3)
C4—N4—C3—C2	−172.48 (15)	C5—C4—C9—C8	−0.8 (3)
N1—C2—C3—N4	14.2 (3)	N4—C4—C9—C8	175.13 (18)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H1N2···S1ⁱ	0.84 (2)	2.55 (2)	3.3672 (18)	164 (2)
N4—H1N4···N5ⁱⁱ	0.82 (3)	2.60 (3)	3.410 (2)	169 (3)
N5—H1N5···N1ⁱⁱⁱ	0.89 (2)	2.48 (2)	3.133 (2)	130 (2)

Symmetry codes: (i) −x+1/2, y−1/2, −z; (ii) x−1/2, y−1/2, z; (iii) x+1/2, y+1/2, z.

Experimental details

Crystal data
Chemical formula	C₁₀H₁₃N₅OS
M_r	251.31
Crystal system, space group	Monoclinic, C2
Temperature (K)	100
a, b, c (Å)	11.5142 (2), 5.8804 (1), 16.6891 (3)
β (°)	95.292 (1)
V (Å³)	1125.17 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.28
Crystal size (mm)	0.33 × 0.18 × 0.02

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.913, 0.994
No. of measured, independent and observed [I > 2σ(I)] reflections	5827, 2365, 2126
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.068, 1.04
No. of reflections	2365
No. of parameters	171
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.33, −0.26
Absolute structure	Flack (1983), 588 Friedel pairs
Absolute structure parameter	0.03 (7)

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), 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
N2—H1N2···S1ⁱ	0.84 (2)	2.55 (2)	3.3672 (18)	164 (2)
N4—H1N4···N5ⁱⁱ	0.82 (3)	2.60 (3)	3.410 (2)	169 (3)
N5—H1N5···N1ⁱⁱⁱ	0.89 (2)	2.48 (2)	3.133 (2)	130 (2)

Symmetry codes: (i) −x+1/2, y−1/2, −z; (ii) x−1/2, y−1/2, z; (iii) x+1/2, y+1/2, z.

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

§Thomson Reuters ResearcherID: A-5523-2009.

Acknowledgements

HKF thanks Universiti Sains Malaysia (USM) for the Research University Golden Goose grant No. 1001/PFIZIK/811012. CSY thanks USM for the award of a USM fellowship. AMI is grateful to the Head of the Department of Chemistry and Director, NITK, Surathkal, India, for providing research facilities.

References

Amir, M., Kumar, H. & Javed, S. A. (2008). Eur. J. Med. Chem. 43, 2056–2066. Web of Science CrossRef PubMed CAS Google Scholar
Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105–107. CrossRef CAS Web of Science IUCr Journals Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Fun, H.-K., Goh, J. H., Vijesh, A. M., Padaki, M. & Isloor, A. M. (2009a). Acta Cryst. E65, o1918–o1919. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Fun, H.-K., Liew, W.-C., Vijesh, A. M., Padaki, M. & Isloor, A. M. (2009b). Acta Cryst. E65, o1910–o1911. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Holla, B. S. & Udupa, K. V. (1992). Farmaco, 47, 305–318. PubMed CAS Web of Science Google Scholar
Isloor, A. M., Kalluraya, B. & Shetty, P. (2009). Eur. J. Med. Chem. 44, 3784–3787. Web of Science CrossRef PubMed CAS Google Scholar
Krzysztof, S., Tuzimski, T., Rzymowska, J., Kazimierz, P. & Kandefer-Szerszeń, M. (2008). Eur. J. Med. Chem. 43, 404–419. Web of Science PubMed Google Scholar
Kuş, C., Ayhan-Kılcıgil, G., Özbey, S., Kaynak, F. B., Kaya, M., Çoban, T. & Can-Eke, B. (2008). Bioorg. Med. Chem. 16, 4294–4303. Web of Science PubMed Google Scholar
Padmavathi, V., Thriveni, P., Reddy, G. S. & Deepti, D. (2008). Eur. J. Med. Chem. 43, 917–924. Web of Science CrossRef PubMed 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