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J. McGinley et al. / Inorganica Chimica Acta 375 (2011) 57–62
Scheme 1. Preparation of 3 and 4. Reaction conditions: (i) 2, Et3N, DCM, Ar, 0 °C and (ii) BBr3, DCM.
2.2. Synthesis of 2
2.4. Synthesis of 4
2-Methoxy-5-nitrobenzoic acid (1.0 g, 5.1 mmol) was heated to
reflux under a guard tube in thionyl chloride (16 mL) for 4 h. The
solution was allowed to cool and the volatiles were removed under
reduced pressure to leave an off white solid (2). Yield quantitative.
m.p.: 84–88 °C (lit: 82–83 °C) [18]. IR (KBr, cmꢀ1): 3115, 3076,
1776, 1755, 1609, 1490, 1287, 1261, 1103, 1002, 750. 1H NMR
(CDCl3): dH = 4.07 (s, 3H, OCH3), 7.14 (d, 1H, ArH, J = 9.2 Hz), 8.47
(dd, 1H, ArH, J = 9.2 and 2.6 Hz), 9.56 (d, 1H, ArH, J = 2.6 Hz).
3 (0.050 g, 0.041 mmol) was dissolved in dry dichloromethane
(10 mL) and the solution was cooled to 0 °C under a flow of nitro-
gen. A 1 M solution of boron tribromide in dichloromethane
(0.065 mL) was added dropwise to the cooled flask. The solution
was allowed to rise to room temperature and stirring was contin-
ued for a further 12 h. The solution was cooled to 0 °C and water
(2 mL) was added dropwise. The solution was stirred for a further
30 min after which the biphasic solution was transferred to a sep-
arating funnel. The aqueous layer was removed and the organic
layer was washed with 1 M hydrochloric acid solution (2 mL) and
saturated brine solution (2 mL). The organic layer was dried over
sodium sulphate, filtered and the solvent removed under reduced
pressure. The residue was dissolved in methanol (3 mL) and pro-
duced immediate precipitation of a white solid. The solid was re-
moved by filtration, washed with methanol and dried in an oven
at 75 °C to give 4. Yield 33% (0.016 g, 0.013 mmol). m.p.: >250 °C.
LC/TCOF-MS: (M+Na)+ requires: 1201.5468 g, found: 1201.5526 g.
IR (KBr, cmꢀ1): 3362, 2960, 1667, 1651, 1607, 1524, 1484, 1341,
1300, 1205, 1126, 1039, 872, 839. 1H NMR (CDCl3): dH = 1.08 (s,
18H, t-Bu), 1.14 (s, 18H, t-Bu), 3.36 (d, 4H, ArCH2Ar, J = 13.2 Hz),
3.78 (m, 8H, NHCH2CH2NH), 4.09 (d, 4H, ArCH2Ar, J = 13.2 Hz),
4.65 (s, 4H, OCH2CO), 6.79 (d, 2H, ArH, J = 9.3 Hz), 6.84 (s, 4H,
ArH), 6.94 (s, 4H, ArH), 8.02 (dd, 2H, ArH, J = 9.3 and 2.3 Hz), 8.22
(s, 2H, OH), 8.55 (br s, 2H, NHOCCH2), 8.64 (d, 2H, ArH,
J = 2.3 Hz), 9.61 (br s, 2H, NHOCPh), 13.48 (s, 2H, OH). 13C NMR
(CDCl3): dC = 30.0, 30.5, 31.0, 32.8, 33.2, 37.6, 38.2, 73.5, 112.3,
117.7, 122.4, 124.5, 125.4, 125.8, 128.0, 131.7, 137.7, 142.1,
147.5, 147.5, 147.9, 166.0, 168.2, 169.0.
2.3. Synthesis of 3
A suspension of (1) (0.84 g, 0.78 mmol) and dry triethylamine
(4 mL) in dry dichloromethane (30 mL) was cooled to 0 °C under
an argon atmosphere. A solution of 2 (0.84 g, 3.90 mmol) in dichlo-
romethane (10 mL) was added dropwise through the septum
whilst maintaining cooling. After addition the solution was al-
lowed to rise to room temperature and the stirring was continued
for 11 h. The volatiles were removed under reduced pressure. The
residue was taken up in methanol (30 mL) and the insolubles were
isolated by filtration. The off white solid was dissolved in chloro-
form (80 mL) and washed with 1 M sodium hydroxide solution
(2 ꢁ 40 mL), 1 M hydrochloric acid solution (2 ꢁ 40 mL) and satu-
rated brine solution (3 ꢁ 40 mL). The organic layer was dried over
magnesium sulphate, the inorganic salts removed by filtration and
the solvent removed under reduced pressure. The residue was
treated with acetone (15 mL) to precipitate a white solid. The solid
was removed by filtration, washed with acetone and dried in an
oven at 75 °C to give 3. A second crop was obtained from the
mother liquor by cooling in a freezer at ꢀ20 °C overnight. Yield
46% (0.43 g, 0.36 mmol). m.p.: 160–164 °C. Anal. Calc. for
2.5. Metal complex titrations
C68H82N6O14: C, 67.63; H, 6.85; N, 6.96. Found: C, 67.81; H, 6.64;
N, 6.83%. IR (KBr, cmꢀ1): 2958, 1655, 1615, 1522, 1485, 1343,
1282, 1192, 1125, 1088, 1016, 874, 823, 749. 1H NMR (CDCl3):
dH = 1.03 (s, 18H, t-Bu), 1.20 (s, 18H, t-Bu), 3.24 (d, 4H, ArCH2Ar,
J = 13.2 Hz), 3.70 (m, 4H, NHCH2CH2NHOCPh), 3.78 (m, 4H,
NHCH2CH2NHOCPh), 3.98 (s, 6H, OCH3) 4.05 (d, 4H, ArCH2Ar,
J = 13.2 Hz), 4.66 (s, 4H, OCH2CO), 6.78 (d, 2H, ArH, J = 9.1 Hz),
6.85 (s, 4H, ArH), 6.88 (s, 4H, ArH), 7.92 (s, 2H, OH), 8.08 (m, 2H,
NHCH2CH2NHOCPh), 8.14 (dd, 2H, ArH, J = 9.1 & 2.8 Hz), 9.00 (d,
2H, ArH, J = 2.8 Hz), 9.12 (m, 2H, NHCH2CH2NHOCPh). 13C NMR
(CDCl3): dC = 29.9, 30.5, 30.9, 32.8, 33.1, 37.0, 39.8, 55.6, 73.7,
110.4, 120.9, 124.3, 125.2, 125.9, 126.8, 127.0, 131.4, 140.5,
141.9, 147.6, 147.7, 148.0, 160.5, 162.4, 168.3.
Metal complexation reactions were performed with either 3
or 4 in either d6-DMSO or a d6-DMSO/H2O mixture using stoichi-
ometric equivalents of metal salt solutions. The metal salts used
were either MIX or MIIX2: M = Na, Ag, Zn, Hg and X = perchlorate,
chloride or acetate.
2.6. Crystal structure determination
Crystallographic Data for 3: data were collected at 150(2) K
on a Bruker APEX II CCD diffractometer. The structure was
solved by direct methods and refined on F2 using all the reflec-
tions [18]. Hydrogen atoms were placed at calculated positions