J. C. Patel et al.
3-(3-Phenyl-acryloyl)-2H-chromen-2-one (L1)
In continuation of our preceding work,[37,38] in the present arti-
cle we describes synthetic, characteristic, spectroscopic features
and thermal aspects of newly synthesized mixed ligand Cu(II)
complexes of 1,10-phenanthroline with coumarin derivatives.
Antituberculosis, antioxidant and antimicrobial screening have
been carried out for all compounds. Isoconversional methods of
Kissinger and Flynn–Wall–Ozawa (FWO) were used to evaluate
an activation energy and pre-exponential factor.
An ethanolic (50 ml) solution of 3-acetyl coumarin (0.01 M) and
benzaldehyde (0.01 M) was placed in a three-neck round-bottom
flask. A catalytic amount of piperidine (1.0 mL) was added in
reaction mass and the mixture was stirred for 10 min at room
temperature. After a clear solution was obtained the reaction
mixture was refluxed in a water bath for 6 h. Completion of the
reaction was monitored by thin-layer chromatography using
mobile-phase ethyl acetate–hexane (7:3). After completion of
the reaction, the mixture was allowed to come at room
temperature. A solid product separated out which was filtered
off, washed with cold ethanol and dried in air. It was recrystallized
from ethanol. Yield 77%; m.p. 142ꢀC. Anal. Calcd for C18H12O3 (%):
C, 78.25; H, 4.38. Found: C, 78.20; H, 4.32. 1H NMR (DMSO-d6
400 MHz): d 6.80 (1H, m, C6═H), 7.11–7.63 (8H, m, aromatic pro-
tons), d 7.77 (1H, d, J = 7.6, CH═CH═ protons), d 7.83 (1H, d,
J= 7.6 CH═CH═ protons), d 8.49 (1H, s, C4═H). 13C NMR (DMSO-d6
100 MHz): d 113.6 (C-4a), 117.1 (C-8), 118.9 (C-10,═CO═CH═),
124.7, 125.3, 126.0, 127.4, 128.8, 129.7, 133.6, 134.2, (eight different
types of aromatic carbons), 146.9 (C-11, ═CH═CH═), 147.3 (C-4),
152.2 (C-8a), 159.3 (C═O, lactone carbonyl of coumarin), 189.5
(C═O, a,b-unsaturated ketone). ESI-MS (m/z): 276.07, FT-IR (KBr,
cmꢁ1): 1610, n (C═O, a,b-unsaturated ketone), 1740, n (C═O, lactone
carbonyl of coumarin).
Experimental
Materials
Salicylaldehyde and ethyl acetoacetate used for the preparation of
3-acetyl coumarin were purchased from E. Merck (India) Ltd,
Mumbai. The nitrate of copper metal ion was used as the hydrated
salt, e.g. Cu(NO3)2.3H2O. Benzaldehyde, vanillin, p-nitrobenzaldehyde,
p-chlrobenzaldehyde and p-hydroxybenzaldehyde were purchased
from Aldrich Chemicals. Catalyst (piperidine) and solvents (chloro-
form, hexane, ethanol, DMSO) were of analytical grade and were
purchased commercially. The organic solvents were purified/dried
by a recommended method.[39]
Physical Measurements
Elemental analysis (C, H, N) was performed using a 2400-II CHN
analyzer (PerkinElmer, USA). Analyses of metal ions was carried
out by dissolution of the solid complexes in hot concentrated
nitric acid, further diluting with distilled water and filtered to re-
move the precipitated organic ligands. The remaining solution
was neutralized with ammonia solution and the metal ions were
titrated against EDTA. The melting point of all compounds was
measured using the open capillary tube method. FT-IR spectra
(400–4000 cmꢁ1) were recorded with a Spectrum GX-PerkinElmer
spectrophotometer using KBr pellets. 1H-NMR and 13C-NMR
spectra of ligands were recorded on a model Advance 400 Bruker
FT-NMR instrument using tetramethylsilane as internal standard and
DMSO-d6 as solvent. The fast atom bombardment (FAB) mass spec-
trum of the complexes was recorded at SAIF, CDRI, Lucknow with a
JEOL SX-102/DA-6000 mass spectrometer at room temperature us-
ing argon/xenon as the FAB gas. Electronic spectra (200–1200 nm)
were collected using a LAMBDA 19 UV–visible/near-infrared spectro-
photometer. Thermal stability and decomposition of the complexes
were determined by TG and DTG using a model 5000/2960 SDT (TA
Instruments, USA). The experiments were performed in N2 atmo-
sphere at a heating rate of 20ꢀC minꢁ1 in the temperature range
20–800ꢀC. Analysis by differential scanning calorimetry (DSC) was car-
ried out using a DSC-PYRIS-1 (PerkinElmer, USA). DSC analyses of
complexes were also evaluated from dynamic scanning experiments
at multiple heating rates of 2.5, 5, 10, 15 and 20ꢀC minꢁ1 respectively,
with the best resolution and comparative results found at a scanning
rate of 10ꢀC minꢁ1. Sample sizes ranging in mass from 3 to 8 mg were
heated in an Al2O3 crucible. Magnetic susceptibility measurements
were obtained by Gouy’s method using mercury tetrathiocyanato
cobaltate(II) as a calibrant (w = 16.44 ꢂ 10ꢁ6 c.g.s. units at 20ꢀC).
Diamagnetic corrections were made using Pascal’s constant.[40]
3-(3-(4-Chlorophenyl)acryloyl)-2H-chromen-2-one (L2)
L2 was synthesized by same method used for L1 by using
p-chlorobenzaldehyde as a substitute of benzaldehyde. Yield 70%;
m.p. 223ꢀC. Anal. Calcd for C18H11ClO3 (%): C, 69.58; H, 3.57. Found:
C, 69.40; H, 3.36. 1H NMR (DMSO-d6 400 MHz): d 6.86 (1H, m, C6═H),
d 7.12 (2H, d, J = 7.2, p-substituted phenyl ring), d 7.23 (1H, m,
aromatic protons), d 7.39 (2H, m, aromatic proton), d 7.63 (2H, d,
J = 7.2, p-substituted phenyl ring), d 7.88 (1H, d, J = 7.8, CH═CH═
protons), d 7.90 (1H, d, J = 7.8, CH═CH═ protons), d 8.52 (1H, s,
C4═H). 13C NMR (DMSO-d6 100 MHz): d 114.8 (C-4a), 116.5 (C-8),
118.6 (C-10, ═CO═CH═), 124.2, 125.1, 126.2, 127.9, 129.8,
130.0, 133.5, 134.6 (eight different types of aromatic carbons),
147.1 (C-11, ═CH═CH═), 147.6 (C-4), 151.5 (C-8a), 159.7 (C═O,
lactone carbonyl of coumarin), 190.2 (C═O, a,b-unsaturated
ketone). ESI-MS (m/z): 310.6, 312.7. FT-IR (KBr, cmꢁ1): 1618, n
(C═O, a,b-unsaturated ketone), 1742, n (C═O, lactone carbonyl
of coumarin).
3-(3-(4-Nitrophenyl)acryloyl)-2H-chromen-2-one (L3)
L3 was synthesized by the same method used for L1 by using
p-nitrobenzaldehyde as a substitute for benzaldehyde. Yield 68%;
m.p. 171ꢀC. Anal. Calcd for C18H11NO5 (%): C, 67.34; H, 3.45; N,
4.39. Found: C, 67.29; H, 3.37; N, 4.36. 1H NMR (DMSO-d6
400 MHz): d 6.90 (1H, m, C6═H), d 7.14 (2H, d, J = 7.2, p-substituted
phenyl ring), d 7.25 (1H, m, aromatic protons), d 7.45 (2H, m,
aromatic proton), d 7.78 (2H, d, J = 7.2, p-substituted phenyl
ring), d 7.86 (1H, d, J = 7.2, CH═CH═ protons), d 7.91 (1H, d,
J = 7.2, CH═CH═ protons), d 8.53 (1H, s, C4═H). 13C NMR (DMSO-
d6 100 MHz): d 114.1 (C-4a), 116.3 (C-8), 118.5 (C-10, ═CO═CH═),
124.9, 125.7, 126.9, 127.1, 129.5, 130.6, 134.8 (seven different
types of aromatic carbons), 146.8 (C-11, ═CH═CH═), 147.2
(C-4), 148.7 (C-17, carbon attached to phenolic NO2), 154.7 (C-8a),
159.6 (C═O, lactone carbonyl of coumarin), 189.7 (C═O,
a,b-unsaturated ketone). ESI-MS (m/z): 321.4, FT-IR (KBr, cmꢁ1):
1614, n (C═O, a,b-unsaturated ketone), 1738, n (C═O, lactone carbonyl
of coumarin), 1523 (ArNO2, asymmetric), 1347 (ArNO2, symmetric).
Synthesis of Ligands (L = L1–L5)
Neutral bidentate ligands were synthesized using Claisen–Schmidt
condensation by a reported method.[41] The Characterization
1
data of ligand L2 and L5(Mass, H NMR, 13C NMR, IR) is given in
Supplementary material(S1–S4 and S6–S9).
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Copyright © 2012 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. (2012)