A. Kormos et al. / Tetrahedron 69 (2013) 8142e8146
8145
3. Conclusion
mixture was poured into a water/ice mixture, and acidified to pH 2
using concentrated hydrochloric acid. The precipitate was filtered
off, and triturated with hot butyl acetate to give 1 or 2 as white
crystals.
In summary, we performed the anion recognition studies of new
5,5-dioxophenothiazine bis(phenylurea) and bis(phenylthiourea)
(1 and 2), which proved to be capable of complexing fluoride in the
presence of bases in acetonitrile. These results suggest that anion
receptors of similar structures with more acidic properties could
provide an opportunity for the development of selective sensor
molecules toward fluoride in basic media.
4.2.1. 1,10-(3,7-Di-tert-butyl-5,5-dioxo-5,10-dihydro-5 6-phenothia-
l
zine-1,9-diyl)bis(3-phenylurea) (1). Yield: 406 mg, 83%; mp
238e240 ꢁC; Rf 0.48 (silica gel TLC, MeOH/CH2Cl2 1:20); IR (KBr)
nmax 3404, 3286, 2960, 2906, 2870, 1650, 1610, 1574, 1510, 1444,
1364, 1296, 1250, 1227, 1142, 1103, 1055, 900, 883, 748, 730, 694,
4. Experimental
4.1. General
611, 540 cmꢀ1; 1H NMR (300 MHz, DMSO-d6)
d 1.34 (s, 18H), 6.92 (t,
J¼8 Hz, 2H), 7.11 (t, J¼8 Hz, 4H), 7.37 (d, J¼8 Hz, 4H), 7.65 (d, J¼2 Hz,
2H), 7.69 (d, J¼2 Hz, 2H), 8.64 (s, 2H, NH), 8.84 (s, 2H, NH), 9.65 (s,
1H, NH); 1H NMR (300 MHz, MeCN-d3)
d 1.36 (s, 18H), 7.00 (t,
Reagents were purchased from SigmaeAldrich Corporation
unless otherwise noted. Silica gel 60 F254 (Merck) plates were used
for TLC. Ratios of solvents for the eluents are given in volumes (mL/
mL). Solvents were dried and purified according to well-established
methods.33
J¼8 Hz, 2H), 7.19 (t, J¼8 Hz, 6H, phenyl H and NH), 7.36 (d, J¼8 Hz,
4H), 7.58 (s, 2H, NH), 7.64 (d, J¼2 Hz, 2H), 7.84 (d, J¼2 Hz, 2H), 9.19
(s, 1H, NH); 13C NMR (75.5 MHz, DMSO-d6)
d 30.88, 34.40, 114.20,
118.58, 121.48, 121.99, 126.66, 126.80, 128.60, 131.08, 139.25, 144.35,
153.71; MS calcd for C34H37N5O4S: 611.2. Found (MꢀH)ꢀ: 610.2.
Anal. Calcd for C34H37N5O4S: C, 66.75; H, 6.10; N, 11.45; S, 5.24.
Found: C, 66.51; H, 5.92; N, 11.18; S, 5.53.
IR spectra were recorded on a Bruker Alpha-T FT-IR spec-
trometer. 1H (500 MHz) NMR spectrum was obtained on a Bruker
DRX-500 Avance spectrometer. 1H (300 MHz) and 13C (75.5 MHz)
NMR spectra were obtained on a Bruker 300 Avance spectrometer.
Elemental analyses were performed on a Vario EL III instrument
(Elementanalyze Corporation). Mass spectra were recorded on an
Agilent-1200 Quadrupole LC/MS instrument using ESI method.
Melting points were taken on a Boetius micro-melting point ap-
paratus and were uncorrected. X-ray crystallographic data were
collected on a Rigaku R-AXIS-RAPID diffractometer (graphite
monochromator). Suitable single crystals for X-ray analysis were
obtained in the following way. Receptor 1: A solution of receptor 1
was prepared in 1:1 acetone/methanol mixture at rt. The solvent
was evaporated slowly, and a few days later crystals appeared in
the ampoule. Receptor 1eDMSO-d6: An almost saturated solution
of receptor 1 was prepared in DMSO-d6 at rt, and a few days later
crystals appeared on the surface of the solution. These crystals
could only be measured in a capillary. Receptor 1eClꢀ: Single
crystals of the 1eClꢀ complex were grown by slow evaporation of
a solution of receptor 1 and an excess of tetrabutylammonium
chloride in a methanol/acetone mixture. Deprotonated 1eFꢀ:
Single crystals of the deprotonated 1eFꢀ complex were grown by
slow evaporation of a solution of receptor 1 and 3 equiv of tet-
rabutylammonium fluoride in an acetonitrile/hexane mixture.
UVevis spectra were taken on a Unicam UV4-100 spectropho-
tometer. Quartz cuvettes with path lengths of 2, 10, and 40 mm
were used. Tetrabutylammonium sulfate was prepared by adding
1 equiv of tetrabutylammonium hydrogen sulfate to 1 equiv of
Bu4NOH dissolved in MeOH. After evaporating MeOH the salt was
dried under reduced pressure over P2O5. All of the other tetrabu-
tylammonium salts of anions were purchased from SigmaeAldrich
Corporation. The stability constants of complexes were determined
by global nonlinear regression analysis using SPECFIT/32Ô pro-
gram. The concentrations of the solutions of receptors 1 and 2 were
4.2.2. 1,10-(3,7-Di-tert-butyl-5,5-dioxo-5,10-dihydro-5 6-phenothia-
l
zine-1,9-diyl)bis(3-phenylthiourea) (2). Yield: 259 mg, 50%; mp
208e210 ꢁC; Rf 0.32 (silica gel TLC, EtOAc/hexane 1:2); IR (KBr) nmax
3354, 3280, 3163, 2962, 1609, 1592, 1542, 1527, 1489, 1290, 1278,
1231, 1130, 746, 695 cmꢀ1; 1H NMR (500 MHz, DMSO-d6)
d 1.32 (s,
18H), 7.11 (t, J¼8 Hz, 2H), 7.25 (t, J¼8 Hz, 4H), 7.48 (d, J¼8 Hz, 4H),
7.60 (d, J¼2 Hz, 2H), 7.74 (d, J¼2 Hz, 2H), 8.45 (s,1H, NH), 9.62 (s, 2H,
NH),10.12 (s, 2H, NH); 13C NMR (125 MHz, DMSO-d6)
d 30.84, 34.45,
115.96, 121.11, 124.22, 124.89, 127.14, 128.51, 130.23, 132.10, 138.79,
144.26, 180.98; MS calcd for C34H37N5O2S3: 643.2. Found (MH)ꢀ:
642.2. Anal. Calcd for C34H37N5O2S3: C, 63.42; H, 5.79; N, 10.88; S,
14.94. Found: C, 63.15; H, 5.67; N, 10.58; S, 14.69.
Acknowledgements
Financial support of the Hungarian Scientific Research Fund
(OTKA No. K 81127, K 75869, and PD 104618) is gratefully ac-
ꢀ
ꢀ
knowledged. The authors express their appreciation to Dr. Matyas
ꢀ
Czugler and Dr. Jozsef Nagy for helpful discussions.
Supplementary data
1H and 13C NMR spectra, NMR titration spectra, additional
UVevis titration spectra, and crystallographic data. Crystallo-
graphic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication nos. CCDC
923802e923805. Copies of the data can be obtained, free of charge,
on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK,
Supplementary data associated with this article can be found in the
1.3, 3.2, and 20 mM during the UVevis titrations. The concentrations
of the solutions of receptor 1 during the NMR titration were
0.77 mM, 1.77 mM, 2.58 mM, 3.37 mM, and 12.5 mM in the cases of
0, 0.25, 0.5, 0.75, and 1e4 equiv of Fꢀ, respectively (more dilute
solutions were needed because of the lower solubility of the
uncomplexed receptor).
References and notes
~
4.2. General procedure for the synthesis of receptors 1 and 2
To a stirred solution of diamine 330 (300 mg, 0.80 mmol) in
pyridine (3 mL) was added a solution of phenyl isocyanate (201 mg,
1.69 mmol) or phenyl isothiocyanate (326 mg, 2.41 mmol) in pyr-
idine (2 mL) at rt. After the reaction was complete, the reaction
ꢀ~
ꢀ
ꢀ