Full Paper
tography (50% to 70% EtOAc in toluene (v/v)) and crystallization
the pseudo-rotaxane geometry, resulting in a higher associa-
from nitromethane, 9 was obtained as a white solid (1.37 g, 23%).
tion constant observed for V1.
3
1H NMR (CDCl3, 400 MHz): d = 7.76 (d, 8H, J(H,H)=8.3 Hz), 7.24 (d,
3
8H, J(H,H)=8.2 Hz), 7.17–7.10 (m, 10H, ArH glycoluril), 6.76 (s, 4H,
2
side-wall), 4.69 (d, 4H, J(H,H)=15.9 Hz), 4.20–4.10 (m, 12H), 3.88–
Conclusion
3.83 (m, 8H), 3.69–3.66 (m, 8H), 3.65–3.61 (m 8H), 2.24 (s, 12H).
13C NMR (CDCl3, 75 MHz): d = 157.27, 146.88, 144.38, 133.17,
132.42, 130.03, 129.65, 129.31, 128.36, 128.22, 127.78, 127.47,
115.77, 84.94, 69.21, 68.98, 68.28, 44.44, 20.93. Maldi-TOF MS (m/z):
1532 [M]+.
The flexibility of the new porphyrin hosts H21 and Zn1 is ex-
pressed in their complex conformational behavior upon the
binding of guests. Insertion of a zinc ion in the porphyrin
causes a structural change in the host cavity which is attribut-
ed to an intramolecular coordination between the zinc ion and
the oxygen atoms in the crown ether-like spacers. The binding
of guests on the inside of the cavities induces large conforma-
tional changes throughout the hosts. Despite the binding of
guests by induced-fit mechanisms, in many cases still high as-
sociation constants are obtained, which shows that not only
“lock and key”, but also “induced-fit” binding can lead to the
formation of strong complexes. Future work is directed on in-
vestigating the threading and catalytic properties of the MnIII
analogue of 1 in a processive system using double bond-con-
taining polymers as substrates.
Free base porphyrin host (H21): A suspension of 9 (120 mg,
0.078 mmol), 5,10,15,20-tetrakis(meso-p-hydroxyphenyl)porphyrin
10 (53 mg, 0.078 mmol), and K2CO3 (100 mg, 0.72 mmol) in DMF
(250 mL) was reacted for 16 h under argon atmosphere at 1108C.
After cooling, filtration of the salts and evaporation of the solvent
the product was purified by column chromatography (3% MeOH
in CHCl3 (v/v)) followed by preparative TLC (7/7/1 toluene/EtOAc/
MeOH (v/v/v). The product was dissolved in a minimal amount of
CHCl3 and to this solution n-hexane was added. A precipitate was
formed, which was collected by centrifugation and dried under
vacuum, yielding 16 mg (13%) of H21 as a purple solid. M.p.>
3008C (dec). 1H NMR (CDCl3 400 MHz): d = 8.79 (s, 4H), 8.77 (s,
3
3
4H), 8.05 (d, 4H, J(H,H)=7.1 Hz), 7.75 (t, 4H, ArH, J(H,H)=7.7 Hz),
7.4–7.35 (m, 8H, ArH), 7.03–6.96 (m, 6H), 6.93–6.90 (m, 4H), 6.37 (s,
2
4H), 4.30 (d, 4H, J(H,H)=15.6 Hz), 4.17–4.11 (m, 4H), 4.00–3.94 (m,
Experimental Section
4H), 3.79 (d, 4H, J=15.5 Hz), 3.12–3.06 (m, 4H), 3.01–2.95 (m, 4H),
2.87–2.81 (m, 4H), 2.69–2.64 (m, 4H), 2.14–2.08 (m, 4H), 1.92–1.86
(m, 4H), À2.62 (s, 2H, NH); see Figure 1 for proton assignments.
13C NMR (CDCl3, 75 MHz): d = 159.23, 157.36, 146.50, 135.42,
133.99, 131.71, 130.25, 129.80, 128.69, 128.50, 127.96, 119.93,
118.75, 115.61, 113.20, 85.30, 70.05, 69.32, 68.43, 68.33, 44.30.
General
All of the syntheses were carried out under an inert nitrogen or
argon atmosphere. Chloroform and acetonitrile used in titration ex-
periments were distilled from CaCl2. Dichloromethane, 1,2-dichloro-
ethane, and methanol were distilled from CaH2. Pyrrole was puri-
fied over a plug of alumina prior to use. Salicylaldehyde was
vacuum distilled. Catechol was recrystallized from dichloromethane
prior to use. MgSO4 and K2CO3 were dried in an oven (1508C). All
other solvents and chemicals were commercial materials and used
as received. Merck silica gel (60H) was used for column chroma-
tography, and Merck silica gel F254 plates were used for thin layer
chromatography and preparative TLC. Molecular modeling calcula-
tions were performed with the use of Spartan (equilibrium geome-
try determination by molecular mechanics using MMFF). Fluores-
cence experiments were performed on a Perkin–Elmer LS50B lumi-
nescent spectrometer equipped with a thermostatted cuvette
holder. UV/Vis spectra were recorded on a Cary 100 Conc (Varian,
Middelburg) UV/Vis spectrometer. Maldi-TOF mass spectrometry
was performed on a Bruker Biflex III spectrometer. NMR spectra
Maldi-TOF MS (m/z): 1522 [M]+. HR-ESI-MS calcd for [C92H80N8O14
+
H]+: 1521.58722; found: 1521.58410. calcd for [C92H80N8O14 +Na]+:
1543.56917; found: 1543.57147.
Zinc porphyrin host (Zn1): Compound H21 (10 mg, 6.6 mmol) and
zinc acetate dihydrate (50 mg 0.23 mmol) were dissolved in a mix-
ture of MeOH and CH2Cl2 (1:1 (v/v), 10 mL). The mixture was stirred
at room temperature for one hour. The solvents were evaporated
and the salts were removed by chromatography over a plug of
silica (eluent MeOH/CHCl3 1:10 (v/v)). After precipitation in n-
hexane, 10 mg (96%) of Zn1 was obtained as a purple solid.
M.p.>3008C. 1H NMR (CDCl3 400 MHz): d = 8.83 (s, 4H), 8.79 (s,
4H), 7.93 (br s, 4H), 7.69 (t, 4H, 3J(H,H)=7.2 Hz), 7.36 (d, 4H,
3J(H,H)=8.1 Hz), 7.24 (br s, 4H), 7.05–6.99 (m, 6H), 6.61 (br, 4H),
6.98 (br s, 4H), 4.02 (br s, 4H), 3.89 (br s, 4H), 3.67 (br s, 4H), 3.47
(br s, 4H), 3.11 (br s, 4H), 2.82 (br s, 4H), 2.78 (br s, 4H), 2.59 (br s,
4H), 2.20 (br s, 4H), 1.95 (br s, 4H); see Figure 3 for proton assign-
ments. 13C NMR ([D6]DMSO, 75 MHz): d = 158.78, 156.55, 149.25,
149.14, 146.58, 135.72, 133.29, 132.28, 130.99, 130.43, 129.50,
128.56, 128.48, 127.74, 119.69, 116.99, 115.81, 113.81, 84.49, 69.04,
68.89, 68.57, 68.45, 43.83.Maldi-TOF MS (m/z): 1585.3 [M]+.
1
were taken on a Varian Inova 400 (400 MHz, H and 2D spectra) or
on a Bruker DMX300 (75 MHz, 13C spectra) and calibrated to an in-
ternal standard of tetramethylsilane. Abbreviations used are: s sing-
let, d doublet, t triplet, dd double doublet, m multiplet. Ditosylate
7,[34,35] tetrakis(chloromethyl)diphenylglycoluril 8,[36] methyl violo-
gen V1, and double-blocked viologen V5[18] were synthesized ac-
cording to literature procedures.
4-(tert-Butyl-diphenyl-silanyloxymethyl)-pyridine (P1): 4-Pyridyl-
carbinol (1.0 g, 9.2 mmol) and imidazole (1.0 g, 14.7 mmol), were
dissolved in CH2Cl2 (50 mL) and tert-butyl-chlorodiphenyl-silane
(3.0 g, 11 mmol) was slowly added to this solution. The mixture
was stirred at room temperature for 4 h, washed with water, the
organic layer was concentrated, and the product was purified by
column chromatography (50% EtOAc/CH2Cl2 (v/v)). Crystallization
from nitromethane yielded 2.1 g (6.04 mmol, 66%) of P1 as a color-
Syntheses
Tetratosyl host molecule (9): Compounds 7 (4.5 g, 7.6 mmol) and
8 (1.8 g, 3.8 mmol) were dissolved in freshly distilled 1,2-dichloro-
ethane (300 mL). SnCl4 (4 mL, 32 mmol) was added and the mixture
was refluxed under argon for 16 h. After cooling, aqueous 6m HCl
(10 mL) was added and the mixture was refluxed for another
30 min. After cooling CH2Cl2 (100 mL) was added and the organic
layer was washed with aqueous 1m HCl (3ꢂ100 mL) and water
and evaporated to dryness. After purification by column chroma-
1
3
less solid. H NMR (CDCl3 400 MHz): d = 8.56 (d, 2H, ArH, J(H,H)=
3
5.2 Hz), 7.67 (d, 4H, J(H,H)=7.2 Hz), 7.35–7.47 (m, 6H), 7.28 (d, 2H,
3J(H,H)=5.2 Hz), 4.76 (s, 2H), 1.12 (s, 9H). 13C NMR (CDCl3 75 MHz):
Chem. Eur. J. 2014, 20, 11574 – 11583
11581
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim