Sulfate Encapsulation in Supramolecular Structures: Anion Binding
(30) [M + H+]. HRMS (ESI): m/z calcd. for C16H28N4O6Na
395.1906; found 395. 1908.
Acknowledgments
Financial support from Council of Scientific and Industrial Re-
search (CSIR), New Delhi and assistance from Natalia A. Platosz,
Department of Chemistry, Rutgers University for help in the prepa-
ration of this manuscript, are gratefully acknowledged.
I.10.3,6-Bis(aminomethyl)piperazine-2,5-dionebis(trifluoroacetic
Acid) (11): To an ice-cooled and stirred solution of BocDKP (10;
0.100 g, 0.268 mmol) in CH2Cl2 (1 mL) was added trifluoroacetic
acid (2 mL) and the reaction mixture was stirred and monitored by
TLC. The reaction was complete within 6 h and, after evaporation,
gave 11 (0.102 g, 96%) as a sticky solid, which was directly used in
the next reaction. 1H NMR (300 MHz, D2O): δ = 4.58 (m, 1 H,
CαH), 3.54–3.39 (m, 2 H, CβH) ppm. 13C NMR (75 MHz, D2O): δ
= 168.18, 51.78, 40.64 ppm. MS (ESI): m/z (%) = 173 (100) [M +
H+].
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II.1. 1,1Ј-(3,6-Dioxopiperazine-2,5-diyl)bis(methylene)bis[3-(3-
nitrophenyl)urea] (12): To a stirred and ice-cooled solution of 11
(0.400 g, 1 mmol) in DMF (20 mL), DIPEA (0.43 mL, 0.322 g,
2.5 mmol) was added. After 30 min, m-nitrophenyl isocyanate
(0.410 g, 2.5 mmol) in CH2Cl2 (10 mL) was added dropwise over
20 min and stirred for 24 h before the solvents were evaporated,
and mixed with methanol (20 mL), filtered, the residue heated to
reflux with methanol (10 mL) for 2 h and filtered to give pure 12
(0.370 g, 74 %); m.p. 246–249 °C. 1H NMR (600 MHz, [D6]-
DMSO): δ = 9.26 (s, 2 H, urea NH), 8.47 (s, 2 H, ArH), 8.3 (br. s,
2 H, amide NH), 7.73 (d, J = 7.88 Hz, 2 H, ArH), 7.59 (d, J =
7.88 Hz, 2 H, ArH), 7.47 (dt, J = 7.88, 8.29 Hz, 2 H, ArH), 6.47
(br. s, 2 H, urea NH), 4.0 (m, 2 H, CαH), 3.45, 3.5 (m, 4 H,
CβH2) ppm. 13C NMR (100 MHz, [D6]DMSO): δ = 167.2, 154.9,
148.0, 141.5, 129.8, 123.6, 115.5, 111.4, 54.2, 41.5 ppm. IR (KBr):
ν = 3341, 3190, 2928, 1684, 1633, 1573, 1446, 1254, 1124 cm–1. MS
˜
(ESI): m/z (%) = 523 (100) [M + Na+], 501 (30) [M + H+]. HRMS
(ESI): m/z calcd. for C20H20N8 NaO8 523.1312; found 523.1301.
II.2. 1,1Ј-(3,6-Dioxopiperazine-2,5-diyl)bis(methylene)bis[3-(4-
nitrophenyl)urea] (13): The reaction of 11 (0.400 g, 1 mmol) and
p-nitrophenyl isocyanate (0.410 g, 2.5 mmol), as described for 12,
afforded 13 (0.380 g, 76%); m.p. 308–310 °C. 1H NMR (400 MHz,
[D6]DMSO): δ = 9.49 (s, 2 H, urea NH), 8.29 (br. s, 2 H, amide
NH), 8.12 (d, J = 8.7 Hz, 4 H, ArH), 7.59 (d, J = 8.7 Hz, 4 H,
ArH), 6.59 (br. s, 2 H, urea NH), 4.01 (m, 2 H, CαH), 3.42, 3.54
(m, 4 H, CβH2) ppm. 13C NMR (100 MHz, [D6]DMSO): δ = 167.1,
154.4, 146.8, 140.4, 125.0, 116.8,54.1, 41.5 ppm. IR (KBr): ν =
˜
3341, 3190, 2928, 1684, 1633, 1573, 1446, 1254, 1124 cm–1. MS
(ESI): m/z (%) = 523 (100) [M + Na+], 501 (30) [M + H+]. HRMS
(ESI): m/z calcd. for C20H20N8 NaO8 523.1312; found 523.1301.
II.3. 1,1Ј-(3,6-Dioxopiperazine-2,5-diyl)bis(methylene)bis[3-(4-
nitrophenyl)thiourea] (14): The reaction of 11 (0.400 g, 1 mmol) and
p-nitrophenyl isothiocyanate (0.450 g, 2.5 mmol), as described for
12, afforded 14 (0.461 g, 86%); m.p. 264–265 °C. 1H NMR
(400 MHz, [D6]DMSO): δ = 10.41 (s, 2 H, urea NH), 8.22 (br. s, 2
H, urea NH), 8.22 (br. s, 2 H, amide NH), 8.17 (d, J = 8.29 Hz, 4
H, ArH), 7.87 (d, J = 7.88 Hz, 4 H, ArH), 4.24 (m, 2 H, CαH),
3.87, 3.94 (m, 4 H, CβH2) ppm. 13C NMR (100 MHz, [D6]DMSO):
δ = 180.2, 167.2, 147.0, 142.9, 124.4, 120.6, 53.8, 45.6 ppm. IR
[12] Crystal data for I: [C20H20N8O8·2(C16H36N)+·SO42–], mono-
clinic, P21, a = 10.0493(3), b = 16.3480(6), c = 18.1821(6) Å, β
= 105.298(2)°, V = 2881.22(1) Å3, Z = 2, μ = 1.05 mm–1, ρ =
1.247 gcm–3, 2θ(max.) = 136.04°, 21848 measured reflections,
8703 unique (Rint = 0.0284, Rs = 0.0220), full-matrix least-
squares refinement [684 parameters on F2, Flack parameter:
–0.01(4) for 3707 Friedel pairs], R1 = 0.075, wR2 = 0.158, for
8703 reflections with IϾ2σ(I), max./min. residual density:
0.78/–0.54 e–/Å3.
(KBr): ν = 3380, 3199, 1673, 1640, 1595, 1557, 1502, 1334, 1253,
˜
1110, 847, 749 cm–1. MS (ESI): m/z (%) = 533 (100) [M + H+].
HRMS (ESI): m/z calcd. for C20H20N8O6 NaS2 555.0827; found
555.0844.
Supporting Information (see footnote on the first page of this arti-
cle): X-ray crystallographic details, 1H NMR spectroscopy titration
studies, titrations and fit curves, 1H and 13C NMR spectra of all
compounds.
[13] Crystal data for II: [4(C20H20N8O6S2)·8(C16H36N)+·4(SO4)2–·
H2O], monoclinic, P21, a = 10.2409(1), b = 19.8608(2), c =
58.5086(6) Å, β = 93.857(1)°, V = 11873.3(2) Å3, Z = 2, μ =
Eur. J. Org. Chem. 2014, 7015–7022
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