2
IBRAHIM ET AL.
refluxed in acetone for 8 h, then the mixture was filtered off,
and washed with acetone. The product ‘methyl 2‐(allyloxy) benzo-
ate’ was obtained by concentration of the filtrate in a vacuum.
2. Synthesis of methyl‐3‐allyl‐2‐hydroxybenzoate based on Claisen
rearrangements.[8] Methyl 2‐(allyloxy) benzoate was refluxed for
24 h. The reaction mixture was cooled in an ice‐bath and the mix-
ture was extracted with ethyl acetate and washed with 0.2 M
NaOH solution. The basic solution was acidified with diluted
HCl. The methyl‐3‐allyl‐2‐hydroxybenzoate was obtained by con-
centrating the filtrate in a vacuum.
FIGURE
1
Chemical structure of 3‐ally‐salicylohydrazide and
dichlorvos
|
2
EXPERIMENTAL
Materials
|
2.1
Terbium chloride hexahydrate (TbCl3.6H2O) of analytical grade was
purchased from Sigma‐Aldrich. The stock solution was prepared in eth-
anol. Solvents were purchased from Sigma‐Aldrich and Fisher
chemicals of high pressure liquid chromatography (HPLC) grade. The
water used was bi‐distilled in the laboratory.
3. Methyl 3‐allyl‐2‐hydroxybenzoate (0.2 mol) and hydrazine
hydrate (0.3 mol) were refluxed in ethanol (100 mL) for 4 h. The
hydrazide was crystallized, filtered off and washed with ethanol.
Further purification was carried out by recrystallization from eth-
anol, yielding a pale butter yellow fine powder of S1. Melting
point = 162–164°C. Elemental Analysis: calculated: (C, 62.49;
H, 6.29; N, 14.57) found (C, 62.39; H, 6.24; N, 14.48). MS (ESI,
Material used in organic synthesis and salts used in work were of
analytical grade and used without further purification including: heavy
metals (nitrate of Ni2+, Cd2+and Pb2+), alkali metals (chlorides of Ca2+
,
,
positive mode): m/z
= 193.2 [M +
H]+, calculated mass
Na+ and K+ also NH4+), anions (sodium salt of CO32−, NO3
2−
for C10H12N2O2 192.22. IR (cm−1 KBr) ν(O − H) phenolic
3445 cm−1, ν(N − H) at 3319 cm−1, ν(C = O) 1638 cm−1, δ(N − H)
amide II band 1584 cm−1. Combination of δ(O − H) deformation
and ν(C − O) stretching vibration 1385–1352 cm−1, ν(C − N)
H2PO4−, HPO42−, Br−, and I−). Pesticides used in this work included
dichlorvos (P1), malathion (P2), Crotoxyphos (P3), chlorpyrifos (P4),
Paraoxon (P5), Profenofos (P6), Endosulfan (P7) and Heptachlor (P8).
All pesticides were of analytical standard brought from Sigma‐Aldrich.
1103 cm−1 1H NMR (850 MHz, DMSO‐d6) δ ppm 3.34 (2H, s,
.
h8), 4.65 (2H, s, NH2), 5.02–5.07 (2H, m, h10), 5.97 (1H, ddt,
h9), 6.79 (1H, m, h4), 7.24–7.27 (1H, m, h3), 7.67 (1H, dd, h5),
10.15–10.24 (1H, m, NH), 13.08–13.23 (1H, m, OH) (Figure S1
and S4).
|
2.2
Chemical and physical measurements
1H–NMR was performed on Bruker Ascend 850 MHz. Infrared spectra
were obtained on a 4100 JASCO Japan FT‐IR. Fluorescence spectra
were performed on a Jasco FP‐6300 spectrofluorometer with a
1.0 cm path using q Hellma quartz cell type 111‐QS with a 150 W
xenon lamp for excitation. Absorption spectra (UV–VIS) were deter-
mined using a Shimadzu UV‐1800, Double Beam photometric system,
and 1.0 cm path length cell. Elemental analysis (CHN) was performed
on a Elementer Vario EL. Mass spectra were recorded on a LTQ XL lin-
ear ion trap mass spectrometer.
|
2.4
Methods
Preparation of complex samples and testing samples was achieved
using stock solutions of materials and by adding a precise volume of
these to the solvent, then mixing. The desired measurement was taken
at room temperature (22–24°C) or using a water bath to raise sample
temperature. Fluorescence measurements were carried out in a 1‐cm
quartz cell and excitation wavelengths were selected based on excita-
tion and absorption spectra.
|
2.3
Ligand preparation
Synthesis of 3‐Ally‐salicylohydrazide (S1): was performed via three
steps, Figure 2 shows the scheme of preparation of the concerned
ligand S1:
|
2.5
Determination of quantum yield
1. A mixture of methyl 2‐hydroxybenzoate (0.1 mol), allyl bromide
The quantum yield (QY) of Tb(III)‐S1 [1:2] was determined in ethanol at a
concentrationof1μM.TheQYwascalculatedwith3‐(2‐benzothiazolyl)‐
7 diethylamino‐coumarin (Coumarin‐6) in ethanol (QY = 0.78) at a
concentration of 1 μM as the reference. Using a diluted solution to
maintain the absorbance values below 0.1 (at excitation wavelength)
(0.15 mol) and anhydrous potassium carbonate (0.2 mol) was
[9]
and to avoid inner filter effects, the QY was calculated using:
AR×IX×n2X
AX×IR×n2R
QX ¼ QR
(1)
where QR is the QY of the reference, AR and AX are absorbances of the
reference (R) and Tb(III)‐B1 (X) at the excitation wavelength (350 nm),
IR and IX are the integrated areas under the corrected emission spectra
of the reference and Tb(III)‐S1 and nR and nx are the refractive indices
FIGURE 2 Method of preparation of the organic ligand L1
of the solutions.