A. Hens
InorganicChemistryCommunications119(2020)108144
ArH), 3.82 (benzyl CH2, s), 2.66 and 2.54 (CH2, t), 2.27 (CH3, s), 4.83
calc
ref
calc
molecule was defined as δX
[ppm] = σX – σX
where TMS was
used as a reference molecule optimized at the same level of theory
[30,31]. In order to account for the solvent effect, I used the integral
(OH, bs).
2.5.2. Synthesis of 2-(((3-(((2-hydroxybenzyl)(2-(dimethylamino)ethyl)
amino)methyl)-2-hydroxy-5-methylbenzyl)(2-(dimethylamino)ethyl)
amino)methyl)phenol [H3L]
2-hydroxyisophthalaldehyde [B] (6.75 g, 45 mmol) was taken in
50 ml dry ether solution and the mixture was stirred for 45 min. It was
followed by stepwise addition Then LiAlH4 was added to this solution
mixture under low temperature and inert N2 atmosphere. The mixture
was stirred for 5 h. After vigorous reduction of carbonyl group the
solvent of the mixture was removed under reduced pressure. The de-
sired crude product 2,6-bis(hydroxymethyl)phenol [C] was dissolved in
minimum volume of acetic acid/ HBr solution (33% of HBr) with stir-
ring for overnight. All the additions were take place under ice cold
condition. Solid crude product was washed by water thoroughly and
dried in vacuum. The obtained crude product 2,6-bis(bromomethyl)
phenol [D] was dissolved in minimum volume of heptane. The white
crystalline product [D] was coming out from the solvent. 12.5 g
(45 mmol) of [D] was taken in dry diethyl ether solution. After
that ~ 25 ml Et3N solution was added to this solution drop wise under
low temperature condition and stirred for 10 min at room temperature.
17.45 g (90 mmol) of previously synthesized reduced Schiff base [A]
was dissolved in dry ether and added drop wise with the solution
containing dissolved [D]. All these arrangements were taken under
nitrogen atmosphere. The whole system was stirred for overnight. The
solvent was then removed by rotary evaporator and extraction was
carried out under DCM: H2O mixture in separating funnel to get crude
product. Finally the DCM solvent was removed by rotary evaporator.
Yield: 26.45 g (90%). Elemental Anal. Calcd. for C31H44N4O3: C, 71.51;
H, 8.52; N, 10.76. Found: C, 71.66; H, 8.49; N, 10.36. ESI-MS (CH3CN):
m/z Calcd. 261.1163, Found: 261.0964 (100%) (H3L + 2H)2+. 1H NMR
{300 MHz, CDCl3, δ (ppm), J (Hz)}: 6.392–6.44 (5H, ArH J = 7.149),
3.51 (H7, s), 3.42 (H10, s), 2.38 (H9, H8, q), 2.30 (H27, s) and 2.12
(H28, s) 4.81 (OH, bs).
2.4. Crystallographic study
The single crystal suitable for X-ray crystallographic analysis of the
complex [Zn2L·2H2O].ClO4·H2O was obtained by slow evaporation of
aqua-methanolic solution. The X-ray intensity data were collected on
Bruker AXS SMART APEX CCD diffractometer (Mo Kα, λ = 0.71073 Å)
at 293 K. The detector was placed at a distance 6.03 cm from the
crystal. Total 606 frames were collected with a scan width of 0.3° in
different settings of φ. The data were reduced in SAINT, SADABS ver-
sion 6.02 and version 2.03 packages [33]. Metal atom was located by
Patterson Method and the rest of the non-hydrogen atoms were
emerged from successive Fourier synthesis. The structure was refined
by full matrix least-square procedure on F2. All non-hydrogen atoms
were refined anisotropically. The structure was solved by direct
methods and refined by full-matrix least squares on F2 using the
SHELXL-2014 package [34] and Olex2 program [34]. Molecular
software. Relevant crystal data are given in table 1.
2.5. Synthesis of complex
2.5.1. Synthesis of 2-((2-(dimethylamino)ethylamino)methyl)phenol [A]
N,N dimethylethanediamine (4.733 g, 45 mmol) was added to the
methanolic solution of salicylaldehyde (5.66 g, 45 mmol) and the
mixture was stirred for 8 h. It was followed by stepwise addition of
sodium cyanoborohydride to this solution mixture under ice cold con-
dition. The solvent was removed under reduced pressure. The crude
mass was subjected to column chromatography on a silica gel column
(60–120 mesh) using 5% ethylacetate in hexane solution. A colorless
solid was obtained after removal of solvent under reduced pressure to
afford the desired reduced Schiff base [A]. Yield: 8.03 g (92%).
Elemental Anal. Calcd. for C11H18N2O: C, 68.01; H, 9.34; N, 14.42.
Found: C, 68.12; H, 9.22; N, 14.36. ESI-MS (CH3CN): m/z Calcd.
194.1430, Found: 194.1784 (100%). 1H NMR {300 MHz, CDCl3, δ
(ppm), J (Hz)}: 8.93 (H1, d, J = 5.9), 8.08 (H10, s), 6.6–6.79 (4H,
2.5.3. Synthesis of complex [Zn2L·2H2O].ClO4·H2O
An aqueous solution of Zn(ClO4).6H2O (0.230 g, 0.60 mM) was
added to a methanolic solution of H3L (0.150 g, 0.29 mM) and the
reaction mixture was warmed in water bath with care. A dilute me-
thanolic solution of Et3N (0.090 g, 0.90 mM) was added to the reaction
mixture to maintain at pH of 7–8; followed by refluxing for 2 h with
afforded air and was then allowed to cool to room temperature. The
reaction mixture was filtered and dried in rotary evaporator to obtain a
white residue. The residue was washed with methanol–water mixture
and finally dried in vacuum. Colorless single crystals suitable for dif-
fraction were obtained from water-methanol (4:1) mixture. Yield:
0.210 g (88%). 1H NMR {δ (ppm) ar = aromatic, Me (N) = amine-
methyl, Me (C) = aromatic-methyl, Bz = benzyl, My = methylene}:
7.41 (H10, ar), 7.22 (H2, ar), 7.19 (H3, ar), 7.01 (H4, ar), 3.88 (H7, Bz),
3.8 (H10, Bz), 2.75 (H8, My), 2.55 (H9, My), 2.33 (H27, Me(N)) and
2.19 (H29, Me(C)). ESI-MS (CH3CN): m/z Calcd. 647.1730, Found:
647.1784 (100%). Molar conductance, ΛM: (CH3CN solution) 126 Ω−1
Table 1
Crystal data and structure refinement parameters for [Zn2L·2H2O]
.ClO4·H2O.
[Zn2L·2H2O].ClO4·H2O
Formula
C31H45ClN4O10Zn2
799.90
Mr
Crystal system
Monoclinic
P21/c
Space group
aÅ
12.5990(4)
24.5485(7)
12.8906(4)
90
b/Å
c/Å
α /°
β/°
cm2 mol−1
.
115.528(2)
90
γ/°
V /Å3
Z
3597.7(2)
4
3. Result and discussion
D
calcd/mg m−3
1.477
3.1. Synthesis and characterization
μ/mm−1
1.466
θ/°
1.659–27.493
273(2)
T /K
The heptadentate symmetrical N4O3 ligand H3L was made to react
with Zn(ClO4)2·6H2O in a ratio of 1:2 in methanol and water mixture at
room temperature in air to produce complex of composition
[Zn2L·2H2O].ClO4·H2O in excellent yield as a form of colorless crystal-
line solid. The synthesis of the complex was given in schematic pre-
GOF on F2
8253
0.0594, 0.1490
1.035
a
b
R1 = Σ∣∣Fo∣- ∣Fc∣∣/ Σ∣ Fo∣.
wR2 = [Σ[w(Fo - Fc2)2]/Σ[w(Fo2)2]]1/2
.
2
3