Browsing by Author "Ching Kheng, C.K."

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1-Cyclohexyl-5-(4-methoxyphenyl)-1H-pyrazole-4-carboxy-lic acid
(2011) Fun, H.-K.; Ching Kheng, C.K.; Chandrakantha, B.; Isloor, A.M.; Shetty, P.
In the title compound, C17H20N2O 3, the meth-oxy-phenyl unit is disordered over two sets of sites in a 0.715 (4):0.285 (4) ratio. The pyrazole ring forms dihedral angles of 55.88 (16) and 72.6 (4)°with the benzene rings of its major and minor components, respectively. The cyclohexane ring adopts a chair conformation and its C-N bond is in an equatorial orientation. In the crystal, molecules are linked into inversion dimers by pairs of O-H?O hydrogen bonds, generating R 2 2(8) loops..
2-(2-Chloro-phenoxy)acetohydrazide
(2010) Fun, H.-K.; Ching Kheng, C.K.; Isloor, A.M.; Dhanya, D.; Shetty, P.
In the title compound, C8H9ClN2O 2, the acetohydrazide group is approximately planar, with the maximum deviation of 0.031 (2) Å. In the crystal, the mol-ecules are linked by N-H?N, N-H?O and C-H?O hydrogen bonds, with the acetohydrazide O atom accepting two C-H?O links and one N-H?O link. This results in infinite sheets lying parallel to (100).
2-(4-Bromo-phen-yl)-2-oxoethyl 2-meth-oxy-benzoate
(2011) Fun, H.-K.; Ching Kheng, C.K.; Garudachari, B.; Isloor, A.M.; Satyanarayan, M.N.
In the title mol-ecule, C 16H 13BrO 4, the dihedral angle between the benzene rings is 85.92 (10)°. In the crystal, mol-ecules are linked into chains along [100] via weak inter-molecular C - H?O hydrogen bonds. © Fun et al. 2011.
2-(4-Chloroanilino)-1-(4-chlorophenyl)ethanone
(2011) Fun, H.-K.; Ching Kheng, C.K.; Vijesh, A.M.; Isloor, A.M.; Arulmoli, T.
In the title compound, C14H11Cl2NO, the benzene rings form a dihedral angle of 3.14 (6)°. Overall, the molecule is close to being planar (r.m.s. deviation for all the non-H atoms = 0.054 Å). No significant directional intermolecular interactions are observed in the crystal structure.
2-(4-Chlorophenyl)-2-oxoethyl 3,4-dimethoxybenzoate
(2011) Fun, H.-K.; Ching Kheng, C.K.; Vijesh, A.M.; Isloor, A.M.; Arulmoli, T.
In the title compound, C17H15ClO5, the benzene rings forms a dihedral angle of 74.45 (10)°. In the crystal, molecules are linked into C(13) chains along [011] via C-H?O hydrogen bonds. The crystal packing also features short Cl?Cl contacts of 3.1253 (10) Å..
2-(4-methylphenoxy)acetohydrazide
(2011) Fun, H.-K.; Ching Kheng, C.K.; Malladi, S.; Vijesh, A.M.; Isloor, A.M.
In the title compound, C9H12N2O 2, the acetohydrazide group is approximately planar [maximum deviation = 0.034 (2) Å]. In the crystal, molecules are linked via intermolecular N - H?O, N - H?N and C - H?O hydrogen bonds into infinite two-dimensional networks parallel to (001).
2-Phenoxy-acetohydrazide
(2010) Fun, H.-K.; Ching Kheng, C.K.; Isloor, A.M.; Dhanya, D.; Shetty, P.
In the title compound, C8H10N2O 2, the acetohydrazide group is almost planar, with an r.m.s. deviation of 0.028 Å. In the crystal, the mol-ecules are linked by inter-molecular C-H?O, N-H?O and N-H?N hydrogen bonds into infinite sheets lying parallel to (001). The acetohydrazide O atom accepts two N-H?O links and one C-H?O link.
3-Ethyl-6-[3-(4-fluoro-phen-yl)-1H-pyrazol-4-yl]-1,2,4-triazolo[3,4-b][1,3, 4]thia-diazole
(2010) Fun, H.-K.; Ching Kheng, C.K.; Malladi, S.; Isloor, A.M.
In the title compound, C14H11FN6S, the 1,2,4-triazolo[3,4-b][1,3,4]thia-diazole ring system is essentially planar [maximum deviation = 0.022 (3) Å] and is inclined at dihedral angles of 15.00 (18) and 52.82 (16)° with respect to the pyrazole and phenyl rings. In the crystal, mol-ecules are linked into two-dimensional networks parallel to (100) via inter-molecular N - H?N and weak C - H?N hydrogen bonds. The crystal packing is further consolidated by weak ?-? stacking inter-actions, with a centroid-centroid distance of 3.590 (2) Å. The crystal studied was an inversion twin with a 0.37 (13):0.63 (13) domain ratio.
4-(1,2,4-triazol-1-yl)aniline
(2011) Fun, H.-K.; Ching Kheng, C.K.; Chandrakantha, B.; Isloor, A.M.; Shetty, P.
In the title compound, C8H8N4, the dihedral angle between the triazole ring [maximum deviation = 0.003 (1) Å] and the benzene ring is 34.57 (7)°. In the crystal, molecules are linked into sheets lying parallel to the ac plane via intermolecular N - H?N and C - H?N hydrogen bonds. Aromatic ?- ? [centroid-centroid distance = 3.6750 (8) Å] stacking and N - H? ? interactions are also observed.
4-Amino-3-(1-naphthyloxymethyl)-1H-1,2,4-triazole-5(4H)-thione
(2010) Fun, H.-K.; Ching Kheng, C.K.; Vijesh, A.M.; Malladi, S.; Isloor, A.M.
In the title compound, C13H12N4OS, the dihedral angle between the triazole and naphthalene ring systems is 67.42 (5)°. In the crystal, adjacent mol-ecules are linked via two pairs of inter-molecular N-H?S inter-actions, forming R 2 2(8) and R 2 2(10) ring motifs. Weak C-H?S inter-actions generate infinite chains along [001] and the structure is further consolidated by C-H?? bonds and aromatic ??? stacking inter-actions [distance between the centroids of the triazole rings = 3.2479 (7) Å].
Bis(4-aminopyridinium) sulfate monohy-drate
(2010) Ching Kheng, C.K.; Fun, H.-K.; Isloor, A.M.; Isloor, N.
The asymmetric unit of the title compound, 2C5H 7N2 +·SO4 2-·H2O, contains two 4-aminopyridinium cations (A and B), a sulfate dianion and a water molecule. One of the 4-aminopyridinium cations (B) is disordered over two orientations with refined site occupancies of 0.568 (4) and 0.432 (4). The non-H atoms of the 4-aminopyridinium cations are essentially coplanar, with a maximum deviation of 0.055 (1) Å (in cation A), 0.022 (3) Å (for the major component in cation B) and 0.009 (3) Å (for the minor component in cation B). In the crystal, the sulfate O atoms link the 4-aminopyridinium cations and water molecules into a three-dimensional network via intermolecular O-H?O, N-H?O and C-H?O hydrogen bonds. The crystal structure is further consolidated by N-H?O(water) and C-H?O(water) hydrogen bonds.
(E)-1-(2,4-Dichlorophen-yl)-3-[3-(4-methoxyphenyl)-1-phenyl-1H-pyrazol-4- yl]prop-2-en-1-one
(2011) Fun, H.-K.; Ching Kheng, C.K.; Malladi, S.; Hebbar, R.; Isloor, A.M.
In the title molecule, C25H18Cl2N 2O2, the dihedral angles between the pyrazole ring and its N- and C-bonded benzene rings are 8.28 (11) and 40.89 (10)°, respectively. The dihedral angle between the benzene rings is 39.03 (11)°. The title molecule exists in a trans conformation with respect to the acyclic C=C bond. In the crystal, molecules are linked into inversion dimers by pairs of inter-molecular C - H?O hydrogen bonds, generating R2 2(14) loops. © Fun et al. 2011.
(E)-1-(2,4-Dichlorophenyl)-3-(1,3-diphenyl-1H-pyrazol-4-yl)prop-2-en-1-one
(2011) Fun, H.-K.; Ching Kheng, C.K.; Malladi, S.; Isloor, A.M.; Shivananda, K.N.
In the title molecule, C24H16Cl2N 2O, the dihedral angles between the pyrazole ring and its N- and C-bonded phenyl rings are 7.06 (10) and 53.15 (10)°, respectively. The dihedral angle between the two pendant rings is 52.32 (10)°. The molecule exists in a trans conformation with respect to the acyclic C=C bond. In the crystal, inversion dimers occur in which each molecule is linked to the other by two C - H?O hydrogen bonds to the same acceptor O atom. There are also short Cl?Cl contacts [3.3492 (9) Å] and C - H?? interactions. © Fun et al. 2011.
(E)-1-(4-Chloro-phen-yl)ethanone semi-carbazone
(2009) Fun, H.-K.; Ching Kheng, C.K.; Padaki, M.; Malladi, S.; Isloor, A.M.
In the title compound, C9H10ClN3O, the semicarbazone group is approximately planar, with an r.m.s. deviation from the mean plane of 0.054 (1) Å. The dihedral angle between the least-squares planes through the semicarbazone group and the benzene ring is 30.46 (5)°. In the solid state, mol-ecules are linked via inter-molecular N - H?O and N - H?N hydrogen bonds, generating R22(9) ring motifs which, together with R22(8) ring motifs formed by pairs of inter-molecular N - H?O hydrogen bonds, lead to the formation of a seldom-observed mol-ecular trimer. Furthermore, N - H?O hydrogen bonds form R21(7) ring motifs with C - H?O hydrogen bonds, further consolidating the crystal structure. Mol-ecules are linked by these inter-molecular inter-actions, forming two-dimensional networks parallel to (100).
(E)-3-[3-(4-Bromophenyl)-1-phenyl-1H-pyrazol-4-yl]-1-(2,4-dichlorophenyl) prop-2-en-1-one
(2011) Fun, H.-K.; Ching Kheng, C.K.; Malladi, S.; Isloor, A.M.; Shivananda, K.N.
In the title molecule, C24H15BrCl2N 2O, the dihedral angles betwen the pyrazole ring and its N-bonded phenyl (A) and C-bonded bromo-benzene (B) rings are 10.34 (16) and 40.95 (15)°, respectively. The dihedral angle between rings A and B is 56.89 (17)°. The title molecule exists in a trans conformation with respect to the acyclic C=C bond. In the crystal, molecules are linked into inversion dimers by pairs of C - H?O hydrogen bonds, generating R 2 2(14) loops. The crystal structure is further consolidated by C - H?? interactions. © Fun et al. 2011.
Ethyl 1,5-diphenyl-1H-pyrazole-4-carboxylate
(2010) Fun, H.-K.; Ching Kheng, C.K.; Chandrakantha, B.; Isloor, A.M.; Shetty, P.
The asymmetric unit of the title compound, C18H 16N2O2, contains two independent molecules (A and B). In molecule A, the pyrazole ring is inclined at angles of 48.86 (6) and 60.80 (6)° with respect to the two phenyl rings; the corresponding angles for molecule B are 46.86 (6) and 58.63 (6)°. In the crystal, molecules of type A are linked into sheets parallel to (001) via weak C-H?O hydrogen bonds, whereas the molecules of type B are linked into chains along [010] via weak C-H?O hydrogen bonds.
Ethyl 1-cyclohexyl-5-(4-methoxyphenyl)-1H-pyrazole-4-carboxylate
(2011) Fun, H.-K.; Ching Kheng, C.K.; Chandrakantha, B.; Isloor, A.M.; Shetty, P.
In the title compound, C19H24N2O 3, the benzene ring forms a dihedral angle of 65.34 (7)°with the pyrazole ring. The cyclo-hexane ring adopts a chair conformation. In the crystal, molecules are linked into a22(22) ring motifs.
Ethyl 1-tert-butyl-5-phenyl-1H-pyrazole-4-carboxylate
(2010) Fun, H.-K.; Ching Kheng, C.K.; Chandrakantha, B.; Isloor, A.M.; Shetty, P.
In the title compound, C16H20N2O 2, the pyrazole ring is essentially planar [maximum deviation = 0.008 (2) Å] and is inclined at an angle of 82.82 (10)° with respect to the phenyl ring. The crystal packing is consolidated by pairs of intermolecular C-H?O hydrogen bonds, which link the molecules into centrosymmetric dimers stacked along the a axis.
Syntheses, crystal structures and antimicrobial studies of two new semicarbazone derivatives
(2014) Chia, T.S.; Ching Kheng, C.K.; Ooi, C.W.; Garudachari, B.; Isloor, N.A.; Isloor, A.M.; Fun, H.-K.
Two new derivatives of semicarbazone, (E)-2-(hexan-2-ylidene) hydrazinecarboxamide and (E)-2-(heptan-2-ylidene)hydrazinecarboxamide were synthesized and characterized by IR and 1H NMR. Their crystal structures were characterized by X-ray diffraction method. Compound (I) crystallizes in triclinic P 1 ?, a = 6.7679(7) Å, b = 7.1912(8) Å, c = 9.9969(11) Å, ? = 108.824(2), ? = 99.398(3), ? = 92.680(2), V = 451.75(8) Å3, Z = 2, R 1 = 0.043 and wR 2 = 0.140. Compound (II) crystallizes in triclinic P 1 ?, a = 6.7192(6) Å, b = 7.2094(6) Å, c = 11.2842(11) Å, ? = 103.303(2), ? = 106.198(2), ? = 91.219(1), V = 508.70(8) Å3, Z = 2, R 1 = 0.044 and wR 2 = 0.133. Their molecules adopt a L-shape conformation with C atom in C=N double bond acting as the junction point. The C=O double bond indicate the existence of semicarbazone group in keto-like form for both compounds in their solid state. In the crystal, the carbonyl O atom for both derivatives acts as a common acceptor in the intermolecular bifurcated N-H·O hydrogen bonding which linked the molecules into one-dimensional supramolecular ribbons. Antimicrobial studies by serial dilution method showed both compounds exhibit antibacterial property. Graphical Abstract: Two new semicarbazone derivatives are characterized by IR, 1H NMR and single crystal X-ray diffraction methods and their antibacterial activity was further investigated by screening against four different bacterial strains.[Figure not available: see fulltext.] © 2013 Springer Science+Business Media New York.
(Z)-1-(2,5-Dichloro-3-thien-yl)ethanone semicarbazone
(2009) Fun, H.-K.; Ching Kheng, C.K.; Vijesh, A.M.; Hegde, C.; Isloor, A.M.
The title mol-ecule, C7H7Cl2N 3OS, is approximately planar [maximum deviation = 0.062 (1) Å]. Short inter-molecular distances between the centroids of the five-membered rings [3.5340 (8) Å] indicate the existence of ?-? inter-actions. An inter-esting feature of the crystal structure is the presence of short intra-molecular Cl?N inter-actions [3.0015 (11) Å]. Mol-ecules are linked via pairs of inter-molecular N - H?O hydrogen bonds, generating R 2 2(8) ring motifs. Furthermore, N - H?O hydrogen bonds form R 2 1(7) ring motifs with C - H?O contacts, further consolidating the crystal structure. In the crystal, mol-ecules are linked by these inter-molecular inter-actions, forming chains along [001]. © 2009 Fun et al.