J. Ravichandran et al. / Journal of Molecular Structure 1062 (2014) 147–157
149
(br s, 1H, NAH proton). 13C NMR (100.52 MHz, CDCl3) d/ppm: 165.6
2.4. General procedure for synthesis of metal complexes
(ArAC@N), 161.2 (CAOH), 132.2, 131.2, 118.5 and 117.0 (aromatic
carbons), 59.2, 56.8, 54.6 and 46.0 (CH2 carbons). Mass EI m/z:
235.16 [L1+2H]+.
All complexes were synthesized using the same procedure as
given below: A methanolic solution (20 mL) of ZnCl2 (0.54 g,
0.004 mol) was added slowly to an equimolar amount of appropri-
ate ligand (HL1–4, 0.004 mol) in methanol (20 mL) with constant
stirring. This mixture was stirred for 2 h, and the reaction was car-
ried out for 6 h under reflux. After cooling the reaction mixture to
room temperature, the resulting product was washed with diethyl
ether and dried in vacuo. Effort was taken to get single crystal,
complex 4 only gave crystals of good diffraction quality and other
complexes went unsuccessful.
2.3.2. Synthesis of 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-
methylphenol, HL2
The solid ligand HL2 was prepared by following the procedure
similar to that of HL1 using 5-methylsalicylaldehyde instead of sal-
icylaldehyde. Yield: 1.92 g, 77.63%. Color: Pale yellow. M.p.:
70.5 °C. Anal. Calc. for [C14H21N3O], (FW: 247.33): C, 67.98; H,
8.56; N, 16.99. Found: C, 67.96%; H, 8.63%; N, 17.02%. IR (KBr,
cmꢃ1): 3275
UV–Vis in methanol solution, kmax/nm (
325 (6089 and 2354,
pꢄ), 413 (826, n ? pꢄ). 1H NMR
m(AOH), 2947
m
(ANH), 1637
m
e
(C@N), 1369
m
(ArAO).
2.4.1. [Zn(HL1)Cl2], 1
/Mꢃ1 cmꢃ1): 246 and
Yield: 1.13 g, 76.4%. Color: Yellow. Anal. Calc. for [C13H19N3OCl2-
Zn], (FW: 369.59): C, 42.24; H, 5.18; N, 11.37. Found: C, 42.29%; H,
p
?
(399.72 MHz, CDCl3) d/ppm: 13.22 (br s, 1H, phenolic proton),
8.30 (s, 1H, imine proton), 7.11 (m, 1H, ArAH), 7.03
(d, J = 1.60 Hz, 1H, ArAH), 6.86 (d, J = 7.99 Hz, 1H, ArAH), 3.73
(t, J = 6.39 Hz, 2H, CH2 protons), 2.89 (t, J = 4.80 Hz, 4H, CH2 pro-
tons), 2.68 (t, J = 7.19 Hz, 2H, CH2 protons), 2.51 (br s, 4H, CH2 pro-
tons), 2.28 (s, 3H, CH3 protons), 1.97 (br s, 1H, NAH proton). 13C
NMR (100.52 MHz, CDCl3) d/ppm: 168.6 (ArAC@N), 158.8 (CAOH),
133.0, 131.2, 127.5, 118.4 and 116.7 (aromatic carbons), 59.3, 56.9,
54.7 and 46.0 (CH2 carbons), 20.3 (CH3). Mass EI m/z: 249.02
[L2+2H]+.
5.28%; N, 11.43%. IR (KBr, cmꢃ1): 3499
m
(AOH str. of CH3OH), 2985
(C@N), 1599
(NAH bend. of NHþ2 )
(ArAO). UV–Vis in DMF solution, kmax/nm (
/Mꢃ1 cmꢃ1):
m
(NAH str. of NHþ2 ), 1621
1355
255 (5778, ?
pꢄ), 328 (1719, n ? pꢄ). ESI-MS (H2O) display peaks
m
m
m
e
p
at: [ZnL1+2H]2+ (302), [ZnL1]+ (299), [L1+H] (234).
2.4.2. [Zn(HL2)Cl2], 2
Yield: 1.26 g, 82.3%. Color: Yellow. Anal. Calc. for [C14H21N3OCl2Zn],
(FW: 383.62): C, 43.83; H, 5.52; N, 10.95. Found: C, 43.86%; H,
5.59%; N, 10.98%. IR (KBr, cmꢃ1): 3489
m
(AOH str. of CH3OH),
(C@N), 1597 (NAH bend.
(ArAO). UV–Vis in DMF solution, kmax/nm
2983
m
(NAH str. of NHþ2 ), 1629
m
m
of NHþ2 ), 1354
m
2.3.3. Synthesis of 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-
chlorophenol, HL3
(e p ?
/Mꢃ1 cmꢃ1): 259 (6361, pꢄ), 338 (1882, n ? pꢄ). ESI-MS
(H2O) display peaks at: [ZnL2+H]2+ (314), [ZnL2]+ (313), [L2+H] (248).
The solid ligand HL3 was prepared by following the procedure
similar to that of HL1 using 5-chlorosalicylaldehyde instead of sal-
icylaldehyde. Yield: 1.96 g, 73.2%. Color: Yellow. M.p.: 69.5 °C.
Anal. Calc. for [C13H18N3OCl], (FW: 267.76): C, 58.31; H, 6.77; N,
15.69. Found: C, 58.29%; H, 6.82%; N, 15.65%. IR (KBr, cmꢃ1):
2.4.3. [Zn(HL3)Cl2], 3
Yield: 1.32 g, 81.9%. Color: Yellow. Anal. Calc. for [C13H18N3OCl3Zn],
(FW: 404.04): C, 38.64; H, 4.49; N, 10.4. Found: C, 38.67%; H, 4.62%;
N, 10.48%. IR (KBr, cmꢃ1): 3447
m
(AOH str. of CH3OH), 2981
(C@N), 1576
(NAH bend. of NHþ2 ), 1348
(ArAO). UV–Vis in DMF solution, kmax/nm (
/Mꢃ1 cmꢃ1): 269
m(NAH
3276
in methanol solution, kmax/nm (
and 1867,
pꢄ), 412 (874, n ? pꢄ). 1H NMR (399.72 MHz, CDCl3)
m
(AOH), 2947
m
(ANH), 1636
m
(C@N), 1360
m
(ArAO). UV–Vis
str. of NHþ2 ), 1627
m
m
e
/Mꢃ1 cmꢃ1): 244 and 326 (6117
m
e
p
?
(7386, p ?
pꢄ), 382 (6953, n ? pꢄ). ESI-MS (H2O) display peaks
d/ppm: 13.24 (br s, 1H, phenolic proton), 8.28 (s, 1H, imine proton),
7.23 (m, 2H, ArAH), 6.893 (d, J = 8.39 Hz, 1H, ArAH), 3.74 (t,
J = 6.99 Hz, 2H, CH2 protons), 2.89 (t, J = 4.60 Hz, 4H, CH2 protons),
2.68 (t, J = 6.79 Hz, 2H, CH2 protons), 2.50 (br s, 4H, CH2 protons),
2.05 (br s, 1H, NAH proton). 13C NMR (100.52 MHz, CDCl3)
d/ppm: 164.4 (ArAC@N), 160.0 (CAOH), 132.0, 130.3, 123.0,
119.5 and 118.6 (aromatic carbons), 59.0, 56.6, 54.6 and 46.0
(CH2 carbons). Mass EI m/z: 269.21 [L3+2H]+.
at: [ZnL3+H]2+ (334), [L3+2H]+ (270), [L3+H] (268).
2.4.4. [Zn(HL4)Cl2], 4
Yield: 1.84 g, 83.1%. Color: Yellow. Anal. Calc. for
[C13H18N3OBrCl2Zn], (FW: 448.49): C, 34.81; H, 4.04; N, 9.37.
Found: C, 34.86%; H, 4.13%; N, 9.42%. IR (KBr, cmꢃ1): 3441
m
(AOH str. of CH3OH), 2979
1586
(NAH bend. of NHþ2 ), 1383
tion, kmax/nm (e p ?
/Mꢃ1 cmꢃ1): 268 (6235, pꢄ), 382 (5133,
m
(NAH str. of NHþ2 ), 1622
m
(C@N),
m
m(ArAO). UV–Vis in DMF solu-
n ? pꢄ). ESI-MS (H2O) display peaks at: [ZnL4]2+ (375), [L4+2H]+
2.3.4. Synthesis of 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-
bromophenol, HL4
(314), [L4+H] (312).
The solid ligand HL4 was prepared by following the procedure
similar to that of HL1 using 5-bromosalicylaldehyde instead of sal-
icylaldehyde. Yield: 2.32 g, 74.30%. Color: Yellow. M.p.: 76 °C. Anal.
Calc. for [C13H18N3OBr], (FW: 312.21): C, 50.01; H, 5.81; N, 13.46.
Found: C, 50.03%; H, 5.86%; N, 13.43%. IR (KBr, cmꢃ1): 3275
2.5. Single crystal X-ray diffraction experiments
Single crystals suitable for X-ray diffraction measurements
were obtained by the slow evaporation of complex 4 in metha-
nol/DMF at room temperature. A pale yellow crystals obtained
was sorted using polarizing microscope (Leica DMLSP). Crystals
having good morphology were chosen for three-dimensional
m
(AOH), 2946
methanol solution, kmax/nm (
and 1882,
pꢄ), 414 (1273, n ? pꢄ). 1H NMR (399.72 MHz,
m
(ANH), 1634
m
(C@N), 1397
m(ArAO). UV–Vis in
e
/Mꢃ1 cmꢃ1): 251 and 328 (6390
p
?
intensity data collection.
A
crystal with dimensions of
CDCl3) d/ppm: 13.29 (br s, 1H, phenolic proton), 8.28 (s, 1H, imine
proton), 7.36 (d, J = 2.59 Hz, 2H, ArAH), 6.85 (d, J = 8.79 Hz, 1H,
ArAH), 3.74 (t, J = 6.99 Hz, 2H, CH2 protons), 2.89 (t, J = 4.80 Hz,
4H, CH2 protons), 2.68 (t, J = 2.99 Hz, 2H, CH2 protons), 2.50 (br s,
4H, CH2 protons), 1.79 (br s, 1H, NAH proton). 13C NMR
(100.52 MHz, CDCl3) d/ppm: 164.3 (ArAC@N), 160.4 (CAOH),
134.8, 133.3, 120.1, 119.1 and 109.8 (aromatic carbons), 59.0,
56.6, 54.6 and 46.0 (CH2 carbons). Mass EI m/z: 313.76 [L4+2H]+.
0.20 ꢅ 0.15 ꢅ 0.10 mm was mounted on a glass fiber for diffraction
experiment. X-ray single crystal data were collected on a ‘Kappa
Apex2 CCD diffractometer’ equipped with a fine-focus sealed tube
X-ray source and graphite monochromated Mo (K
the wavelength (k) of 0.71073 Å at room temperature (293 2 K).
The intensity data were collected using and scans with frame
a) radiation in
x
u
width of 0.5°. The frame integration and data reduction were per-
formed using ‘Bruker SAINT-plus’ (Version 7.06a) software. Empir-