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A. Karmakar et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 159 (2016) 141–145
Scheme 1. Synthetic scheme of crown 1.
1,1-bis-(2-hydroxynaphthyl)phenylmethane (2a): A mixture of
2-naphthol (1.44 g, 10 mmol), benzaldehyde (0.584 g, 5.5 mmol) and
(
)-camphor-10-sulfonic acid (0.232 g, 1.0 mmol) in dry acetonitrile
was stirred at ambient temperature (25 °C). After 16 h, TLC showed
complete consumption of both the starting materials. The solid thus
formed was quenched with water, filtered, washed with water and
dried in air. The crude solid was recrystallized with hexane-ethyl
acetate to afford pure 2a (1.41 g, 75%).
2a: pink solid; mp 195–196 °C; IR (CHCl3): υ 3471, 3423, 3019, 1618,
1597,1513, 1491, 1468, 1390, 1253, 1046, 877 cm−1 1H NMR
;
(200 MHz, CD3COCD3): δ 7.13–7.38 (m, 12 H, ArCHAr, ArH), 7.74–7.84
(m, 4 H, ArH), 8.12 (d, J = 8.3 Hz, 2 H, ArH); 13C NMR (50 MHz,
CD3COCD3): δ 43.0, 120.1, 120.4, 123.6, 123.7, 126.8, 127.5, 128.8,
129.1, 129.7, 130.0, 130.5, 135.2, 143.3, 154.0; HRMS: m/z calc. for
Fig. 1. Structure of the xanthenocrown-5 (1) and bis-napthalenocrown-6 (2) and
bis(benzimidazolium)propane borontetrafluoride (BBIM-propane axels) (3a–3d).
C
27H20O2Na (M+Na): 399.1361; found: 399.1365.
bis-Napthalenocrown-6 (2): A mixture of 2a (0.790 g, 2.1 mmol),
pentaethyleneglycolditosylate (1.26 g, 2.3 mmol, 1.1 equiv) and
Cs2CO3 (1.73 g, 5.3 mmol, 2.5 equiv) in dry acetonitrile (30 ml) was
refluxed for 8 h when TLC showed complete consumption of both 2a
and the ditosylate. The solvent was removed under vacuo, cooled,
quenched with 1 N HCl and extracted with ethyl acetate. The organic
layer was washed with water, brine and dried (Na2SO4). Removal of
solvent afforded a thick mass which was purified by silica gel column
chromatography (using CHCl3 as eluant) to afford pure 2 (0.948 g, 78%).
2: light yellow solid; mp 155–156 °C; IR (CHCl3): υ 3058, 3016, 2874,
1622, 1598, 1511, 1492, 1451, 1451, 1295, 1259, 1243,1215, 1176, 928,
temperature controller unit (TCC −240 A). The steady state fluorescence
emission and excitation spectra were recorded with a Hitachi F-4500
spectrofluorometer equipped with a temperature controlled cell holder.
Temperature was controlled within 0.1 K by circulating water from a
constant temperature bath (Heto Holten, Denmark). Monte Carlo simu-
lations were performed using Spartan'14 molecular modeling software
from Wavefuntion Inc. (Irvine, CA, USA). Using Monte Carlo simulation
[12], global minima search for all the eight optimized complexes
neglecting solvent were performed using Merck molecular force-field
calculations (MMFF). Energy of the simulated equilibrium conformers
as well as global minima were calculated using single point calculation
by DFT/MPW1PW91 functional using 6-31G* basis set in Gaussian09.
806, 697 cm−1 1H NMR (200 MHz, CDCl3): δ 2.88–2.98 (m, 2 H,
;
OCH2CH2O), 3.10–3.21 (m, 2 H, OCH2CH2O),3.31–3.35 (m, 4 H,
2 × OCH2CH2O), 3.45–3.48 (m, 8 H, 4 × OCH2CH2O), 3.69–3.71 (m,
2 H, OCH2CH2O), 3.77–3.83 (m, 2 H,OCH2CH2O), 7.03–7.14 (m, 6 H,
ArCHAr, ArH), 7.23–7.30 (m, 6 H, ArH), 7.73–7.81 (m, 6 H, ArH); 13C
NMR (50 MHz, CDCl3):
2.3. Synthetic procedure of crown 1 and crown 2
δ 43.9, 68.4, 68.9, 70.3, 116.1, 122.7124.0, 124.8, 125.2, 125.8, 127.5,
128.1, 128.2, 128.7, 129.4, 133.4, 144.9, 155.2; HRMS:m/z calc. for
C
Xanthenocrown-5 (1): A mixture of 2-naphthol (1.44 g, 10 mmol),
4-formyl benzo-15-crown-5 (1a) (1.63 g, 5.5 mmol) and ( )-camphor-
10-sulfonic acid (CSA) (0.17 g, 0.75 mmol) in 2 ml of acetonitrile was
taken in a microwave vessel and irradiated (400 W, 63–64 °C) under
microwave. After 45 min, TLC showed complete consumption of the
starting material (2-naphthol) and formation of 1 as the only product.
The reaction mixture was quenched with saturated aqueous sodium
bicarbonate solution and extracted with ethyl acetate. The organic
layer was washed with brine, dried (Na2SO4) and evaporated under
reduced pressure to obtain a thick mass which was purified by column
chromatography on silica using CHCl3 as eluant to afford pure 1 (2.52 g,
92%).
37H39O6 (M+H): 579.2747; found: 579.2731.
3. Result and discussions
3.1. Photophysical study
Fig. 2 shows the electronic absorption spectra of two mixtures con-
taining (1 + 3d) and (2 + 3d) respectively in acetonitrile medium. To
obtain the CT bands, spectra of above solution (in acetonitrile medium)
1: pink solid; mp 187–188 °C; IR (CHCl3): υ 3017, 2929, 1636, 1593,
1513, 1456, 1431, 1401, 1250, 1240, 1215, 1139 cm−1 1HNMR
;
(200 MHz, CDCl3): δ 3.62 (s, 8 H, 4 × OCH2CH2O), 3.72–3.80 (m, 4 H,
2 × OCH2CH2O), 3.91–3.93 (m, 4 H, 2 × OCH2CH2O), 6.41 (s, 1 H,
ArCHAr), 6.63 (d, J = 8.2 Hz, 1 H, ArH), 6.93–6.94 (m, 1 H, ArH), 7.08
(dd, J = 8.2, 1.8 Hz, 1 H, ArH),7.37–7.48 (m, 4 H, ArH), 7.53–7.60 (m,
2 H, ArH), 7.80 (t, J = 9.1 Hz, 4 H, ArH), 8.37 (d, J = 8.5 Hz, 2 H, ArH);
13C NMR (50 MHz, CDCl3): δ 37.3, 69.0, 69.1, 69.5, 70.6, 70.9, 114.0,
114.9, 117.4, 117.8, 121.1, 122.7, 124.1, 126.6, 128.7, 131.0,
131.4138.2, 147.7, 148.7, 149.1; MS, m/z (%) = 571 (M+Na, 100).
Scheme 2. Synthetic scheme of crown 2.