Modified BINOL podands: Synthesis of dinaphthosulfide podands and their application in spectrophotometric determination of toxic metals

Article abstract of DOI:10.1080/10426500701372272

New dinaphthosulfide podands [3(a, b, and c)] were synthesized. The structures of these compounds were confirmed by IR, 1H NMR, 13C NMR, and Mass spectra. A simple, efficient, and sensitive procedure is described for the spectrophotometric determination of a trace amount of Ag+, Hg2+, Cr3+, Pb2+, and Ni2+ cations in the presence of Mn2+, Co2+, Cd2+ cations using the podand (3a). Formation constants of 1:1 complexes were determined from the absorbance-mole ratio data and found to vary in the order Pb2+ Ni2+ Hg2+ Cr3+ Ag+.

Full text of DOI:10.1080/10426500701372272

Phosphorus, Sulfur, and Silicon, 182:2115–2123, 2007
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500701372272
Modified BINOL Podands: Synthesis of Dinaphthosulfide
Podands and Their Application in Spectrophotometric
Determination of Toxic Metals
Abbas Shockravi
Marzieh Chaloosi
Esmael Rostami
Davood Heidaryan
Ali Shirzadmehr
Hanif Fattahi
Hamid Khoshsafar
Faculty of Chemistry, Tarbiat Moallem University, Tehran, Iran
New dinaphthosulfide podands [3(a, b, and c)] were synthesized. The structures
of these compounds were confirmed by IR, 1H NMR, 13C NMR, and Mass spectra.
A simple, efficient, and sensitive procedure is described for the spectrophotometric
determination of a trace amount of Ag+, Hg2+, Cr3+, Pb2+, and Ni2+ cations in the
presence of Mn2+, Co2+, Cd2+ cations using the podand (3a). Formation constants
of 1:1 complexes were determined from the absorbance-mole ratio data and found
to vary in the order Pb2+ > Ni2+ > Hg2+ > Cr3+ > Ag+.
Keywords BINOL; chromium; diamide; dinaphthosulfide; lead; Podand; spectrophotom-
etry; sulfide
INTRODUCTION
The design of a chemosensor for a cation or anion requires a receptor
unit or ligand that selectively interacts with the cation or anion, and a
method to read-out the binding using a change in a physical signal is a
very attractive subject in chemistry.1 This is due to the special structure
of their flexible donor atom containing chain and podand receptor sites
which can form complexes with many cations ranging from alkali and
alkaline earth metals to transition metals. By chemical modification of
Received January 17, 2007; accepted March 12, 2007.
We wish to thank and appreciate the Ministry of Science, Research, and Technology
of Islamic Republic of Iran (nano section), and also the Ministry of Research at Tarbiat
Moallem University in Tehran for their financial support.
Address correspondence to Abbas Shockravi, Faculty of Chemistry, Teacher Training
University, No. 49, Mofatteh Avenue, Tehran 15614, Iran. E-mail: shockravi @ yahoo.co.uk
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A. Shockravi et al.
the arms (e.g., changing the chain length or the donor atom) and under
certain experimental conditions, podand receptors can selectively form
complexes with metal ions.2
As a recognition motif, podand based receptors have been reported
to be used successfully as recognition components in electrochemi-
cal sensors3,4 and optical sensors.5−7 In order to construct ionophore
model systems, various macrocyclic compounds, such as crown ethers,
cryptands, and calixarenes, have been synthesizd and structurally char-
acterized. In addition to these macrocyclic compounds, podands have
been employed as noncyclic ionophore models.8
BINOL ((1, 1ꢀ-di (2-hydroxy naphthalene)) derivatives are an impor-
tant group of compounds which have been studied by many researchers
including our group.9 In continuation of our previous studies on the
synthesis of new dibenzosulfide and dibenzosulfoxide monomers and
macrocyclic compounds,10 we now wish to report new interesting di-
naphthosulfide podands (3(a, b and c)) as modified BINOL podands
and the podand (3a) was used in the determination of Ag+, Hg2+, Cr3+
,
Pb2+, and Ni2+ cations.
The dinaphthosulfide (1) was synthesized from 2-naphthol in a 76%
yield.11 The treatment of (1) with the α-chloroamides (2 (a, b and c)
in the presence of K2CO3 at reflux acetonitrile gave (3(a, b and c))
in 93%, 88% and 83% yields respectively (Scheme 1). α-Chloroamides
were synthesized from the reaction of various amines with chloroacetyl
chloride.
RESULTS AND DISCUSSION
In this work, the synthesis of some new podands (3(a, b and c)) by
the reaction of some α-chloroamides with (1) are described. Our motive
behind the synthesis of this type of ligands was to examine their possible
application in the cation recognition processes.
The electronic absorption spectra of the ligand (3a) with various con-
centrations are represented in (Figure 1). An examination of (Figure 1)
indicates that the electronic spectra of this ligand are largely dependent
on the concentration. Increasing the compound concentration results in
increasing the absorbance of both bands at 260.2 and 308.2 nm, where
beyond a certain concentration of the compound a very broad band is
observed. This behavior can be ascribed to the association of molecule
through intermolecular hydrogen bonding.
The electronic absorption spectra of the ligand and the complexes
with Ag+, Hg2+, Cr3+, Pb2+, Co2+, Mn2+, Cd2+ and Ni2+ in the same
concentration of cations are shown in (Figure 2). Under identical ex-
perimental conditions, the absorption characteristics of the complexes

Dinaphthosulfide Podands
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SCHEME 1
in solution are listed in (Table 1). As can be noticed, the electronic
spectra of the ligand-Co, Mn and ligand-Cd does not show absorptions.
Therefore, there are no interferences from Co2+, Cd2+, and Mn2+ in the
determination of Ag+, Hg2+, Cr3+, Pb2+, and Ni2+ with this ligand.
For evaluation of the formation constants from the absorbance vs
CM/CL mole ratio data, a non-linear, least-squares, curve fitting pro-
gram KINFIT was used.12 The program is based on the iterative ad-
justment of calculated values of absorbance to observed values by using
either the Wentworth matrix technique13 or the Powell procedure.14

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A. Shockravi et al.
Figure 1 Electronic spectra of the 3a ligand in DMSO at 1) 5×10−3 M, 2)
5×10−4 M, 3) 1×10−4 M, 4) 5×10−5 M, 5) 1×10−6 M.
One of the typical fitting curves of podand (3a) with cations us-
ing the above software are illustrated in (Figure 3), which clearly
shows that a 1:1 Pb2+ to (3a) complex is formed in solution. The re-
sults of formation constants are shown in (Table 1). As is evident from
(Table 1), the complexes stabilities of these cations with (3a) decrease
in the order of Pb2+ >Ni2+ >Hg2+ >Cr3+ >Ag+.
EXPERIMENTAL
All the experiments for the synthesis of podands were performed in an
efficient fume hood cupboard. All the materials were analytical reagent-
grade chemicals and pure solvents were purchased from Merck, Aldrich,
and Fluka chemical companies. Doubly distilled water was used for the
preparation of aqueous solutions. The podands were synthesized and
purified as described herein.
For spectrophotometric experiments, reagent grade nitrate salts
of lead, nickel, silver, mercury, cobalt, manganese, cadmium, and
chromium were available in highest purity and used without any fur-
ther purification.
UV-Vis absorption spectrophotometry was used for quantification of
complexation process. A set of solutions containing (3a) (1 × 10−6 M)

Dinaphthosulfide Podands
2119
Figure 2 Electronic spectra of complexes of 3a with 1) Cr2+, 2) Pb2+, 3) Ni2+
4) Ag+, 5) Hg2+, 6) Co2+, 7) 3a, 8) Mn2+, 9) Cd2+ in DMSO.
,
TABLE I Formation Constants and Maximum Wavelengths of Mn+
with Podand (3a) (in DMSO, at 23 1 C)
Pb
(II)
Hg
(II)
Ni
(II)
Cr
(III)
Ag
(I)
Mn Cd Co
(II) (II) (II) L∗
λ
264.4
261.2
276
267.6
261
258 257.8 259 260.2
max
(nm)
LogKf 4.81 0.04 1.23 0.03 2.12 0.19 0.8 0.06 0.45 0.25
—
—
—
—
∗L: Ligand.
with 100 ppm concentration of cations were placed in a UV cell of 1cm
path length in order to perform the spectrophotometric analysis. All
experiments were carried out at conditioned room temperature (23
1◦C).

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A. Shockravi et al.
Figure 3 Computer fit of absorbance vs Pb+2/(3a) mole ratio plot at 23
1
C:(x) experimental point; (o) calculated point; (=) experimental and calculated
points are the same within the resolution of the plot.
Apparatus
The melting points (uncorrected) were measured on an electrothermal
engineering LTD9100 apparatus. Mass spectra were obtained with Shi-
madzu GC-MS-QP 1100 EX model. IR spectra were measured on a
Perkin-Elmer model 543; 1H NMR and 13C NMR spectra were obtained
using Bruker Avance DRX 300 MHz apparatus. Absorption measure-
ments were recorded on a Philips UV-Vis spectrophotometer (Pu8750)
model.
Ligand Synthesis and Procedures—General Procedure
for the Preparation of α-Chloroamides
To a vigorously stirred solution of amine (0.002 mol (a 0.29 g, b 0.24
g and c 0.39 g)) and triethylamine (0.002 mol, d = 0.73 g/ml, 0.15 ml)
in an appropriate dried solvent (50 ml, CH2Cl2) was added a solution
of chloroacetyl chloride (0.002 mol, d = 1.42 g/ml, 0.32 ml) in the
same solvent (50 ml) at 0◦C. The reaction mixture was stirred at room
temperature for 6 h. The reaction mixture was quenched with distilled
water and then was extracted with CH2Cl2 (2 × 50 ml). The combined
organic layer was washed with 10% aqueous HCl solution (50 ml)
and water (50 ml), dried (Na2SO4), and evaporated to afford solid

Dinaphthosulfide Podands
2121
products which were purified by recrystallization from the appropriate
solvent.
Synthesis of (2a)
This compound was purified by recrystallization from ethanol to
afford brown crystals in 92% yield, mp 125–128◦C; IR (KBr): 3337,
3029, 2975, 1683, 1598, 1551, 1490, 1471, 1430, 1395, 1334, 1279, 833,
769 cm−1; 1H NMR (300 MHz, CDCl3): δ 4.32 (s, 2H), 7.46-7.50 (dd, J =
4.2 Hz, 1H), 7.55-7.59 (m, 2H), 8.17, 8.20 (d, J = 9 Hz, 1H,), 8.73-8.79
(m, 1H) 8.86, 8.86 (d, J = 3 Hz, 1H) ppm; 13C NMR (300 MHz, CDCl3):
δ 43.36, 116.82, 121.72, 122.56, 127.23, 127.97, 133.50, 136.48, 138.56,
148.55, 164.41 ppm.
Synthesis of (2b)
This compound was purified by recrystallization from ethanol to af-
ford white crystals in 81% yield, m.p. 99–101◦C; IR (KBr): 3264, 3059,
2978, 1658, 1601, 1546, 1489, 1443, 1418, 1368, 1342, 1231, 1198, 1104,
1
927, 784 cm−1; H NMR (300 MHz, CDCl3): δ 1.53, 1.56 (d, J = 9 Hz,
3H), 4.00–4.11 (dd, J = 15 Hz, 2H), 5.10–5.19 (m, 1H), 6.82 (b, 1H),
7.26–7.38 (m, 5H) ppm; 13C NMR (300 MHz, CDCl3): δ 21.64, 42.62,
49.22, 126.05, 127.61, 128.77, 142.28, 164.91 ppm.
Synthesis of (2c)
This compound was purified by recrystallization from ethanol to afford
white crystals in 86% yield, m.p. 150–153◦C; IR (KBr): 3341, 1667, 1598,
1535, 1504, 1442, 1410, 1315, 1252, 1158, 850, 787 cm−1; 1H NMR (300
MHz, CDCl3): δ 4.24(s, 2H), 7.45–7, 7.56 (m, 3H), 7.72–7.76 (m, 2H),
7.89–7.99 (m, 4H), 8.40 (broad, 1H) ppm; 13C NMR (300 MHz, CDCl3):
δ 42.89, 120.08, 122.81, 124.05, 129.10, 130.97, 139.06, 149.60, 152.59,
163.83 ppm.
Following the published procedures11 to a solution of 2-naphthol
(10 mmol, 1.44 g) in diethyl ether (50 ml) at room temperature a solu-
tion of SCl2(5.5 mmol, 0.92 ml, d = 1.62 g/ml) in diethyl ether (50 ml)
was added dropwise over a period of 1 h. After stirring for 2 h at room
temperature, the resulting precipitate was filtered and washed with
diethyl ether (2 × 30 ml), and then it was recrystallized from ethanol
to afford the product in 76% yield as white needles, m.p. = 212–214◦C.
General Procedure for the Preparation of Diamide Podands
To a mixture of (1) (1 mmol, 0.32 g) and potassium carbonate (2 mmol,
0.28 g) in CH3CN (50 ml) was added α-chloroamides (2 mmol(2a 0.44 g,

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A. Shockravi et al.
2b 0.40 g and 2c 0.55g)), and the suspension mixture was allowed to cool
to room temperature and subsequently poured into 700 ml of distilled
water. The precipitate was filtered and recrystallized from appropriate
solvents.
Synthesis of 1,1’- thiobis[2-(quinolin-8”-acetamide-2”-oxy]
naphthalene (3a)
This compound was purified by recrystallization from ethanol to af-
ford brown crystals in 93% yield, m.p. 190–193◦C; IR (KBr): 3348, 3059,
1687, 1616, 1592, 1536, 1500, 1483, 1459, 1383, 1327, 1261, 1204, 1148,
1077, 800, 754 cm−1; 1H NMR (300 MHz, CDCl3): δ 4.69 (s, 2H), 7.32–
7.34 (t, 1H), 7.39-7.44 (m, 2H), 7.52–7.58 (m, 3H), 7.77, 7.80 (d, J = 9
Hz, 1H), 8.10, 8.12 (d, J = 6 Hz, 1H), 8.39, 8.42 (d, J = 9 Hz, 1H), 8.52,
8.53 (d, J = 3 Hz, 1H), 8.73-8.76 (d, J = 9 Hz, 1H), 8.89, 8.92 (d, J =
9 Hz, 1H), 10.89 (s, 1H); 13C NMR (300 MHz, CDCl3): δ 68.47, 115.21,
117.24, 119.59, 122.33, 123.64, 124.09, 124.85, 127.22, 128.42, 129.39,
129.52, 130.22, 131.08, 133.18, 134.37, 141.35, 147.76, 151.98, 156.41,
166.76 ppm; MS: 115(35%), 116(40%), 143(100%), 170(60%), 187(40%),
257(10%), 316(15%), 358(20%).
Synthesis of 1,1’- thiobis[2-( phenyl ethyl amine-N-
acetamide-α-oxy)] naphthalene (3b)
This compound was purified by recrystallization from ethanol to af-
ford white crystals in 88% yield, mp 160–163◦C; IR (KBr): 3342, 3058,
3033 2978, 1652, 1589, 1526, 1501, 1458, 1279, 1211, 1070, 808, 693
cm −1; 1H NMR (300 MHz, CDCl3): δ 1.19, 1.22 (d, J = 9 Hz, 3H), 4.31–
4.42 (dd, J = 16 Hz, 2H), 5.02–5.07 (m, 1H), 6.83–6.86 (d, J = 9 Hz, 1H),
6.96–7.10 (m, 6H) 7.36–7.46 (m, 2H), 7.68–7.76 (dd, J = 9 Hz, 2H), 8.49,
8.52 (d, J = 8 Hz, 1H); 13C NMR (300 MHz, CDCl3): δ 68.47, 115.21,
117.24, 119.59, 122.33, 123.64, 124.09, 124.85, 127.22, 128.42, 129.39,
129.52, 130.22, 131.08, 133.15, 134.37, 141.35, 147.76, 151.98, 156.41,
166.76 ppm; MS: 98(42%), 109(38%), 130(25%), 145(35%), 158(100%),
161(38%), 215(40%), 298(18%).
Synthesis of 1, 1’-thiobis[2-(azobenzene-4”-acetamide-α-oxy)]
naphthalene (3c)
This compound was purified by recrystallization from ethanol to
afford yellow crystals in 83% yield, mp 259–262◦C; IR (KBr): 3313,
3056, 1682, 1598, 1533, 1505, 1412, 1304, 1262, 1240, 1090, 809,
684 cm−1 1H NMR (300 MHz, CDCl3): δ 4.84 (s, 2H), 7.32–7.34 (t,
;
J = 3 Hz, 1H), 7.39–7.44 (m, 2H), 7.52–7.58 (m, 3H), 7.78-7.90 (m,
8H), 8.52-8.55 (d, J = 9 Hz, 1H), 10.36 (s, 1H) ppm; 13C NMR (300
MHz, CDCl3): δ 68.47, 115.21, 117.24, 119.59, 122.33, 123.64, 124.09,

Dinaphthosulfide Podands
2123
124.85, 127.22, 128.42, 129.39, 129.52, 130.22, 131.08, 134.37, 141.35,
147.76, 151.98, 156.41, 166.76 ppm; MS: 73(30%), 74(60%), 77(60%),
87(45%), 93(35%), 115(50%), 120(70%), 144(100%), 149(40%), 160(38%),
225(20%), 246(18%), 275(23%), 299(38%).
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