Synthesis of some novel tetraimidazolium salts derived from diphenyl- and dimethylglycolurils

Article abstract of DOI:10.1007/s00706-007-0805-0

Several new tetrabromo compounds based on diphenyl- and dimethylglycolurils were synthesized. Sequential treatment of these compounds with imidazole, methyl iodide, and sodium tetrafluoroborate gave their corresponding tetra imidazolium salts. Some of the

Full text of DOI:10.1007/s00706-007-0805-0

Monatsh Chem 139, 639–645 (2008)
DOI 10.1007/s00706-007-0805-0
Printed in The Netherlands
Synthesis of some novel tetraimidazolium salts derived from diphenyl-
and dimethylglycolurils
Mohammad Rahimizadeh, Esmaeel Rezaei Seresht, Neda Golari, Mehdi Bakavoli
Department of Chemistry, School of Sciences, Ferdowsi University, Mashhad, Iran
Received 26 August 2007; Accepted 6 September 2007; Published online 12 May 2008
# Springer-Verlag 2008
Abstract Several new tetrabromo compounds based
on diphenyl- and dimethylglycolurils were synthe-
sized. Sequential treatment of these compounds with
imidazole, methyl iodide, and sodium tetrafluorobo-
rate gave their corresponding tetra imidazolium salts.
Some of these compounds because of their low melt-
ing points can be registered as a potential and new
class of ionic liquids.
molecular clips with a large variety of side walls
have been synthesized, and the supramolecular chem-
istry of these clips has been extensively studied [4].
Some effort has been directed toward modifying the
glycoluril framework of the hosts. The urea func-
tionalities in the glycoluril framework have been
replaced by thiourea and guanidine groups [5] and
clips have been synthesized starting from dimethyl-
glycoluril [6], dipyridylglycoluril [7], ditoluylglyco-
luril [8], and bipyridylglycoluril [9].
Keywords Receptors; Heterocycles; Electrophilic substitu-
tion; Molecular clips; Ionic liquids.
Introduction
The design and synthesis of host molecules for the
binding of neutral guest molecules continues to be
an area of interest in supramolecular chemistry [1].
In the past decade, Nolte and his co-workers in-
troduced a series of host molecules derived from
the concave molecule diphenylglycoluril which were
able to bind neutral aromatic guest molecules, such
as resorcinol [2].
These ‘‘U-shaped’’ clips bind dihydroxybenzenes
by means of hydrogen bonding between the hydrox-
yl groups of the guest and the urea carbonyl groups
of the host and by ꢀꢀꢀ stacking interactions be-
tween the guest and the host side walls [3]. Also,
Correspondence: Mehdi Bakavoli, Department of Chemistry,
School of Sciences, Ferdowsi University, Mashhad 91375-
1436, Iran. E-mail: mbakavoli@yahoo.com
Scheme 1

640
M. Rahimizadeh et al.
Scheme 2
Scheme 3

Novel tetraimidazolium salts
641
In this paper we describe the synthesis of new mo-
lecular clips which contain four alkyl arms substituted
with bromine atoms, imidazole, and imidazolium rings.
The building block 9 was prepared from urea and
1,2-diphenylethanedione under azeotropic distilla-
tion [11]. Subsequent reaction of 9 with paraformal-
dehyde in the presence of NaOH in DMSO yielded
the cyclic ether 10 [12] (Scheme 2). The glycoluril
derivative 11 that was used as second building block
was synthesized from urea and 2,3-butanedione [13].
Reaction of 11 with formaldehyde solution yielded
the cyclic ether 12 [13].
Results and discussion
The starting 2 was prepared by bromination of 1,4-
bis(2-hydroxyethoxy)benzene (1) using carbon tetra-
bromide and triphenylphosphine [10]. Compounds
3–5 were obtained from hydroquinone by means of a
base-catalyzed oxygen alkylation reaction with 6–8
(Scheme 1).
To obtain the clip molecules 13–19, the cyclic
ethers 10 and 12 were reacted with the aromatic side
walls 2–5 in a mixture of acetic anhydride and TFA
Scheme 4

642
M. Rahimizadeh et al.
at 110ꢁC. The reaction took place via a Friedel-
Crafts alkylation mechanism (Scheme 3).
mixturewas concentrated invacuo and the resulting residuewas
partitioned between 150 cm3 water and 150cm3 chloroform.
The organic layer was evaporated to dryness and the precipi-
tate was washed with sodium hydroxide solution (3ꢂ50 cm3,
1 N), water (2ꢂ50 cm3), and n-hexane (2ꢂ50 cm3), and
dried in vacuo.
Spectral evidence and elemental analyses clearly
confirmed the formation of the molecular clips 13–
19. For example, the 1H NMR spectrum of 14 showed
the methyl protons as a singlet at ꢁ ¼ 1.75ppm, the
methylene protons of the four bromoalkyl arms as
two multiplets at ꢁ ¼ 3.56–3.66 and 4.06–4.26ppm,
the nonequivalent CH2N protons as two doublets at
ꢁ ¼ 3.89 and 5.47 ppm (J ¼ 16Hz), and finally the
aromatic protons as a singlet at ꢁ ¼ 6.63 ppm.
1,4-Di(3-bromopropoxy)benzene (3, C12H16Br2O2)
The title compound was obtained according to the general pro-
cedure starting with 6 and hydroquinone. Yield 12.7g (40%);
mp 64–66ꢁC; 1H NMR (100 MHz, CDCl3): ꢁ ¼ 2.29 (qui, J ¼
6 Hz, 4H), 3.80 (t, J ¼ 6 Hz, 4H), 4.05 (t, J ¼ 6 Hz, 4H), 6.84
(s, 4H) ppm; IR (KBr): ꢂꢀ¼ 822, 1030, 1233, 1505, 2945cmꢀ1
1,4-Di(4-bromobutoxy)benzene (4, C14H20Br2O2)
.
The molecular clips 13–19 could now be used
as starting materials for the preparation of several
new clips (20–26). So, upon reaction of 13–19 with
an excess of imidazole in DMF in the presence of
KOH, the clip molecules 20–26 were synthesized
The title compound was obtained according to the general pro-
cedure starting with 7 and hydroquinone. Yield 18.8g (55%);
mp 82–84ꢁC; 1H NMR (100 MHz, CDCl3): ꢁ ¼ 1.70–2.20 (m,
8H), 3.48 (t, J ¼ 6 Hz, 4H), 3.94 (t, J ¼ 6 Hz, 4H), 6.81 (s, 4H)
1
ppm; IR (KBr): ꢂꢀ¼ 826, 1017, 1233, 1510, 2946 cmꢀ1
1,4-Di[(6-bromohexyl)oxy]benzene (6, C18H28Br2O2)
.
(Scheme 3). In the H NMR spectrum of 21, three
singlet peaks pertaining to the imidazole rings pro-
tons appeared clearly at ꢁ ¼ 6.88, 7.04, and 7.59 ppm.
In the next step, 20–26 were converted to imidazo-
lium salts 27–33 using methyl iodide as methylating
agent. These salts were water-soluble and the treat-
ment of them with sodium tetrafluoroborate in hot
water gave 34–40 via an anion exchange reaction
(Scheme 4). The success of the methylation was
The title compound was obtained according to the general
procedure starting with 8 and hydroquinone. Yield 15.7g
(40%); mp 81–83ꢁC; 1H NMR (100 MHz, CDCl3): ꢁ ¼
1.04–1.40 (m, 8H), 1.65–2.00 (m, 8H), 3.41 (t, J ¼ 6 Hz,
4H), 3.90 (t, J ¼ 6 Hz, 4H), 6.80 (s, 4H) ppm; IR (KBr):
ꢂꢀ¼ 835, 1035, 1225, 1510, 2950 cmꢀ1
.
3a,6a-Diphenylperhydroimidazo[4,5-d]imidazole-2,5-dione
1
(9) was synthesized according to Ref. [11]; IR and H NMR
1
confirmed well by the H NMR spectra. Firstly, by
emerging of a singlet peak belonging to the methyl
groups bonded to the positively charged nitrogen
atoms and secondly, by taking place of downfield
shifts in the imidazole rings protons due to the positive
charge created on the rings. So in the 1H NMR spec-
trum of 35, the methyl groups bonded to the posi-
tively charged nitrogens appeared as a singlet at ꢁ ¼
3.94ppm and the imidazole rings protons were ob-
served as three singlets at ꢁ ¼ 7.52, 7.73, and 9.09 ppm.
spectra of the compound were identical with the one described
in Ref. [11].
8b,8c-Diphenylperhydro-2,6-dioxa-3a,4a,7a,8a-tetraaza-
cyclopenta[def]fluorene-4,8-dione (10) was synthesized ac-
cording to Ref. [12]; IR and 1H NMR spectra of the
compound were identical with the one described in Ref. [12].
3a,6a-Dimethylperhydroimidazo[4,5-d]imidazole-2,5-dione
(11) was synthesized according to Ref. [13]; mp 343–345ꢁC.
8b,8c-Dimethylperhydro-2,6-dioxa-3a,4a,7a,8a-tetraazacy-
clopenta[def]fluorene-4,8-dione (12) was synthesized accord-
ing to Ref. [13]; mp 350.
Experimental
General Procedure for Synthesis of Molecular Clips 13–19
A 2.64mmol cyclic ether 10 and 12 were dissolved in a
mixture of 2.64 cm3 TFA and 2.64cm3 acetic anhydride and
the solution was heated at 95ꢁC for 30min. Then, 5.28 mmol
dibromo 2–5 were added to the solution and the mixture
heated for 1 h. After cooling, MeOH was added carefully
and the resulting precipitate was filtered off, washed with
MeOH, and dried in vacuo.
Melting points were recorded on an Electrothermal type 9100
melting point apparatus. The IR spectra were obtained on a
4300 Shimadzu spectrometer and only noteworthy absorptions
are listed. The 1H NMR (100 MHz) spectra were recorded on
a Bruker AC 100 spectrometer. Chemical shifts are reported in
ppm downfield from TMS as internal standard; coupling con-
stant J are given in Hertz. Elemental analysis was performed
on a Thermo Finnigan Flash EA microanalyzer. 1,4-Di(2-bro-
moethoxy)benzene (2) was synthesized according to Ref. [10];
mp 111–113ꢁC.
1,4,8,11-Tetra(2-bromoethoxy)-13b,13c-diphenyl-5,7,12,
13b,13c,14-hexa-hydro-5a,6a,12a,13a-tetraazabenzo-
[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(13, C40H38Br4N4O6)
General procedure for synthesis of aromatic side walls 3–5
A mixture of 0.36 mol dibromo 6–8, 9.90g hydroquinone
(90 mmol), and 37.26 g potassium carbonate (0.27mol) in
60cm3 acetone was refluxed under N2 for 24 h. The reaction
The title compound was obtained according to the general
procedure starting with 2 and 10. Yield 1.96g (75%);

Novel tetraimidazolium salts
643
1
mp 244–246ꢁC; H NMR (CDCl3): ꢁ ¼ 3.45–4.40 (m, 20H),
1,4,8,11-Tetra[(6-bromohexyl)oxy]-13b,13c-dimethyl-5,7,12,
13b,13c,14-hexa-hydro-5a,6a,12a,13a-tetraazabenzo-
[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(19, C46H66Br4N4O6)
5.55 (d, J ¼ 16Hz, 4H), 6.59 (s, 4H), 7.09 (s, 10H) ppm; IR
(KBr): ꢂꢀ¼ 1090, 1260, 1505, 1690, 3065cmꢀ1
.
1,4,8,11-Tetra(2-bromoethoxy)-13b,13c-dimethyl-5,7,12,
13b,13c,14-hexa-hydro-5a,6a,12a,13a-tetraazabenzo-
[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(14, C30H34Br4N4O6)
The title compound was obtained according to the general
procedure starting with 5 and 12. Yield 2.59g (90%); mp
176–180ꢁC; 1H NMR (CDCl3): ꢁ ¼ 1.33–2.17 (m, 32H),
1.66 (s, 6H), 3.41 (t, J ¼ 6 Hz, 8H), 3.65–4.10 (m, 12H),
5.42 (d, J ¼ 16Hz, 4H), 6.68 (s, 4H) ppm.
The title compound was obtained according to the gen-
eral procedure starting with 2 and 12. Yield 1.83 g
(80%); mp 259–262ꢁC; 1H NMR (CDCl3): ꢁ ¼ 1.75 (s,
6H) 3.54–4.40 (m, 20H), 5.47 (d, J ¼ 16 Hz, 4H), 6.62 (s,
4H) ppm; IR (KBr): ꢂꢀ¼ 1090, 1265, 1360, 1500, 1690,
General procedure for synthesis of molecular clips 20–26
To a mixture of 0.90g KOH (16mmol) in 10 cm3 DMF was
added 0.27 g imidazole (4mmol) and the mixture was stirred
at room temperature for 30min. Then, a solution of 1 mmol
tetrabromo clips 13–19 in 10cm3 DMF was gradually added
and the reaction mixture was stirred at room temperature for
24h. The reaction mixture was poured into 200 cm3 water,
filtered, and the product was dried in vacuo.
2920 cmꢀ1
.
1,4,8,11-Tetra(3-bromopropoxy)-13b,13c-diphenyl-5,7,12,
13b,13c,14-hexahydro-5a,6a,12a,13a-tetraazabenzo-
[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(15, C44H46Br4N4O6)
1,4,8,11-Tetra[2-(1H-1-imidazolyl)ethoxy]-13b,13c-diphenyl-
5,7,12,13b,13c,14-hexahydro-5a,6a,12a,13a-tetraaza-
benzo[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(20, C52H50N12O6)
The title compound was obtained according to the general
procedure starting with 3 and 10. Yield 2.00g (73%);
1
mp 250–253ꢁC; H NMR (CDCl3): ꢁ ¼ 2.36 (qui, J ¼ 6 Hz,
8H), 3.55–3.90 (m, 12H), 4.07 (t, J ¼ 6 Hz, 8H), 5.55 (d,
J ¼ 16 Hz, 4H), 6.72 (s, 4H), 7.08 (s, 10H) ppm; IR (KBr):
The title compound was obtained according to the general
procedure starting with 13 and imidazole. Yield 0.81g
(86%); mp 285–289ꢁC; 1H NMR (CDCl3): ꢁ ¼ 3.74 (d,
J ¼ 16 Hz, 4H), 4.05–4.55 (m, 16H), 5.51 (d, J ¼ 16 Hz,
4H), 6.52 (s, 4H), 7.02 (s, 4H), 7.13 (s, 14H), 7.68 (s, 4H)
ꢂꢀ¼ 1070, 1255, 1460, 1705, 2940 cmꢀ1
.
1,4,8,11-Tetra(3-bromopropoxy)-13b,13c-dimethyl-5,7,12,
13b,13c,14-hexahydro-5a,6a,12a,13a-tetraazabenzo-
[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(16, C34H42Br4N4O6)
ppm; IR (KBr): ꢂꢀ¼ 1240, 1462, 1705, 2960, 3070cmꢀ1
.
1,4,8,11-Tetra[2-(1H-1-imidazolyl)ethoxy]-13b,13c-dimethyl-
5,7,12,13b,13c,14-hexahydro-5a,6a,12a,13a-tetraaza-
benzo[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(21, C42H46N12O6)
The title compound was obtained according to the general
procedure starting with 3 and 12. Yield 1.90g (78%); mp
1
132–134ꢁC. H NMR (CDCl3): ꢁ ¼ 1.89 (s, 6H), 2.32 (qui,
J ¼ 6 Hz, 8H), 3.50–4.20 (m, 20H), 5.45 (d, J ¼ 16 Hz, 4H),
6.72 (s, 4H) ppm; IR (KBr): ꢂꢀ¼ 1100, 1260, 1355, 1470,
The title compound was obtained according to the general
procedure starting with 14 and imidazole. Yield 0.56g
1695, 2940 cmꢀ1
.
1
(69%); mp 248–252ꢁC; H NMR (CDCl3): ꢁ ¼ 1.71 (s, 6H)
3.65–4.35 (m, 20H), 5.36 (d, J ¼ 16 Hz, 4H), 6.40 (s, 4H),
1,4,8,11-Tetra(4-bromobutoxy)-13b,13c-diphenyl-5,7,12,-
13b,13c,14-hexahydro-5a,6a,12a,13a-tetraazabenzo-
[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(17, C48H54Br4N4O6)
6.88 (s, 4H), 7.04 (s, 4H), 7.59 (s, 4H) ppm; IR (KBr):
.
ꢂꢀ¼ 1260, 1355, 1470, 1700, 3075cmꢀ1
1,4,8,11-Tetra[3-(1H-1-imidazolyl)propoxy]-13b,13c-diphenyl-
5,7,12,13b,13c,14-hexahydro-5a,6a,12a,13a-tetraaza-
benzo[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(22, C56H58N12O6)
The title compound was obtained according to the general
procedure starting with 4 and 10. Yield 2.53g (87%); mp
199–202ꢁC; 1H NMR (CDCl3): ꢁ ¼ 1.70–2.35 (m, 16H),
3.30–4.13 (m, 20H), 5.50 (d, J ¼ 16 Hz, 4H), 6.62 (s, 4H),
7.03 (s, 10H) ppm; IR (KBr): ꢂꢀ¼ 1070, 1254, 1353, 1461,
The title compound was obtained according to the general
procedure starting with 15 and imidazole. Yield 0.85g
(86%); mp 230–233ꢁC; 1H NMR (CDCl3): ꢁ ¼ 2.03 (qui,
J ¼ 6 Hz, 8H), 3.50–4.08 (m, 12H), 4.22 (t, J ¼ 6 Hz, 8H),
5.67 (d, J ¼ 16 Hz, 4H), 6.59 (s, 4H), 6.90 (s, 4H), 7.01 (s,
4H), 7.16 (s, 10H), 7.52 (s, 4H) ppm; IR (KBr): ꢂꢀ¼ 1255,
1711, 2925 cmꢀ1
.
1,4,8,11-Tetra(4-bromobutoxy)-13b,13c-dimethyl-5,7,12,-
13b,13c,14-hexahydro-5a,6a,12a,13a-tetraazabenzo-
[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(18, C38H50Br4N4O6)
1358, 1465, 1705, 2970cmꢀ1
.
1,4,8,11-Tetra[3-(1H-1-imidazolyl)propoxy]-13b,13c-dimethyl-
5,7,12,13b,13c,14-hexahydro-5a,6a,12a,13a-tetraaza-
benzo[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(23, C46H54N12O6)
The title compound was obtained according to the general
procedure starting with 4 and 12. Yield 2.37g (92%); mp
1
176–179ꢁC; H NMR (CDCl3): ꢁ ¼ 1.63 (s, 6H) 1.75–2.24
(m, 16H), 3.43 (t, J ¼ 6 Hz, 8H), 3.65–4.10 (m, 12H), 5.37
(d, J ¼ 16 Hz, 4H) 6.64 (s, 4H) ppm; IR (KBr): ꢂꢀ¼ 1088,
The title compound was obtained according to the general
procedure starting with 16 and imidazole. Yield 0.60g
1254, 1356, 1465, 1703, 2942 cmꢀ1
.

644
M. Rahimizadeh et al.
1
(69%); mp 86–88ꢁC; 1H NMR (CDCl3): ꢁ ¼ 1.78 (s, 6H), 2.04
(qui, J ¼ 6 Hz, 8H), 3.50–4.30 (m, 20H), 5.54 (d, J ¼ 16Hz,
4H), 6.55 (s, 4H), 6.83 (s, 4H), 6.95 (s, 4H), 7.43 (s, 4H) ppm;
(81%); mp 275–278ꢁC; H NMR (Acetone-d6): ꢁ ¼ 3.83 (d,
J ¼ 16 Hz, 4H), 4.01 (s, 12H), 4.34–4.50 (m, 8H), 4.76 (t,
J ¼ 6 Hz, 8H), 5.52 (d, J ¼ 16 Hz, 4H), 6.77 (s, 4H), 7.16 (s,
10H), 7.57 (s, 4H), 7.77 (s, 4H), 9.21 (s, 4H) ppm; IR (KBr):
IR (KBr): ꢂꢀ¼ 1085, 1260, 1473, 1702, 3055cmꢀ1
.
ꢂꢀ¼ 1104, 1231, 1370, 1464, 1710, 2935 cmꢀ1
.
1,4,8,11-Tetra[4-(1H-1-imidazolyl)butoxy]-13b,13c-diphenyl-
5,7,12,13b,13c,14-hexahydro-5a,6a,12a,13a-tetraaza-
benzo[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(24, C60H66N12O6)
1-[2-(13b,13c-Dimethyl-4,8,11-tri[2-(3-methyl-1H-imidazol-
3-ium-1-yl)ethoxy]-6,13-dioxo-5,7,12,13b,13c,14-hexahydro-
5a,6a,12a,13a-tetraazabenzo[5,6]azuleno[2,1,8-ija]benzo-
[f]azulen-1-yloxy)ethyl]-3-methyl-1H-imidazol-3-ium
tetrakis(tetrafluoroborate) (35, C46H58B4F16N12O6)
The title compound was obtained according to the general
procedure starting with 17 and imidazole. Yield 0.90 g
(86%); mp 163–166ꢁC; 1H NMR (CDCl3): ꢁ ¼ 1.60–2.25
(m, 16H), 3.60–4.23 (m, 20H), 5.58 (d, J ¼ 16Hz, 4H), 6.60
(s, 4H), 6.95 (s, 4H), 7.10 (s, 14H), 7.55 (s, 4H), 7.08 (s,
10H) ppm; IR (KBr): ꢂꢀ¼ 1073, 1256, 1353, 1461, 1706,
The title compound was obtained according to the general
procedure starting with 21 and methyl iodide. Yield 0.20 g
1
(82%); mp 225–227ꢁC; H NMR (Acetone-d6): ꢁ ¼ 1.84 (s,
6H), 3.94 (s, 12H), 4.14 (d, J ¼ 16Hz, 8H), 4.25–4.40 (m,
8H), 4.73 (t, J ¼ 6 Hz, 8H), 5.32 (d, J ¼ 16Hz, 4H), 6.74 (s,
4H), 7.52 (s, 4H), 7.73 (s, 4H), 9.09 (s, 4H) ppm; IR (KBr):
2934 cmꢀ1
.
1,4,8,11-Tetra[4-(1H-1-imidazolyl)butoxy]-13b,13c-dimethyl-
5,7,12,13b,13c,14-hexahydro-5a,6a,12a,13a-tetraaza-
benzo[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(25, C50H62N12O6)
ꢂꢀ¼ 1090, 1272, 1365, 1475, 1690, 3050 cmꢀ1
.
1-[2-(13b,13c-Diphenyl-4,8,11-tri[3-(3-methyl-1H-imidazol-
3-ium-1-yl)propoxy]-6,13-dioxo-5,7,12,13b,13c,14-hexahydro-
5a,6a,12a,13a-tetraazabenzo[5,6]azuleno[2,1,8-ija]benzo-
[f]azulen-1-yloxy)ethyl]-3-methyl-1H-imidazol-3-ium
The title compound was obtained according to the general
procedure starting with 18 and imidazole. Yield 0.62 g
(67%); mp 110–113ꢁC; 1H NMR (CDCl3): ꢁ ¼ 1.72 (s,
6H), 1.80–2.25 (m, 16H), 3.65–4.10 (m, 20H), 5.48 (d,
J ¼ 16 Hz, 4H), 6.59 (s, 4H), 6.88 (s, 4H), 6.98 (s, 4H),
7.49 (s, 4H) ppm; IR (KBr): ꢂꢀ¼ 1084, 1255, 1357, 1697,
tetrakis(tetrafluoroborate) (36, C60H70B4F16N12O6)
The title compound was obtained according to the general
procedure starting with 22 and methyl iodide. Yield 0.21 g
(76%); mp 194–196ꢁC; 1H NMR (Acetone-d6): ꢁ ¼ 2.35
(qui, J ¼ 6 Hz, 8H), 3.70–4.20 (m, 24H), 4.69 (t, J ¼ 6 Hz,
8H), 5.63 (d, J ¼ 16Hz, 4H), 6.78 (s, 4H), 7.23 (s, 4H), 7.61
(s, 4H), 7.72 (s, 4H), 9.01 (s, 4H) ppm; IR (KBr): ꢂꢀ¼ 1095,
2931 cmꢀ1
.
1,4,8,11-Tetra[6-(1H-1-imidazolyl)hexyl]oxy-13b,13c-dimethyl-
5,7,12,13b,13c,14-hexahydro-5a,6a,12a,13a-tetraaza-
benzo[5,6]azuleno[2,1,8-ija]benzo[f]azulene-6,13-dione
(26, C58H78N12O6)
1260, 1370, 1465, 1695, 3070cmꢀ1
.
The title compound was obtained according to the general
procedure starting with 19 and imidazole. Yield 0.72 g
1-[2-(13b,13c-Dimethyl-4,8,11-tri[3-(3-methyl-1H-imidazol-
3-ium-1-yl)propoxy]-6,13-dioxo-5,7,12,13b,13c,14-hexahydro-
5a,6a,12a,13a-tetraazabenzo[5,6]azuleno[2,1,8-ija]benzo-
[f]azulen-1-yloxy)ethyl]-3-methyl-1H-imidazol-3-ium
1
(69%); viscous oil; H NMR (CDCl3): ꢁ ¼ 1.15–2.05 (m,
32H), 1.89 (s, 6H), 3.60–4.15 (m, 20H), 5. 49 (d, J ¼ 16 Hz,
4H), 6.65 (s, 4H), 6.91 (s, 4H), 7.03 (s, 4H), 7.47 (s,
4H) ppm.
tetrakis(tetrafluoroborate) (37, C50H66B4F16N12O6)
The title compound was obtained according to the general
procedure starting with 23 and methyl iodide. Yield 0.21 g
(82%); mp 68–70ꢁC; 1H NMR (Acetone-d6): ꢁ ¼ 1.93
(s, 6H), 2.30 (qui, J ¼ 6 Hz, 8H), 3.70–4.35 (m, 24H), 4.62
(t, J ¼ 6 Hz, 8H), 5.44 (d, J ¼ 16Hz, 4H), 6.76 (s, 4H), 7.56 (s,
4H), 7.65 (s, 4H), 8.96 (s, 4H) ppm; IR (KBr): ꢂꢀ¼ 1105,
General procedure for synthesis of molecular clips 34–40
A solution of 0.2 mmol tetraimidazo clips 20–26, 5 cm3 meth-
yl iodide, and 5 cm3 dichloromethane was refluxed for 16h.
After concentration in vacuo, the oily residue was dissolved in
30cm3 hot water and then a solution of 0.21 g sodium tetra-
fluoroborate (2mmol) in 15 cm3 water was added and the
reaction mixture was stirred at room temperature for 48h.
Finally, the product was filtered off, washed with water, and
dried in vacuo.
1265, 1370, 1470, 1705, 3050cmꢀ1
.
1-[2-(13b,13c-Diphenyl-4,8,11-tri[4-(3-methyl-1H-imidazol-
3-ium-1-yl)butoxy]-6,13-dioxo-5,7,12,13b,13c,14-hexahydro-
5a,6a,12a,13a-tetraazabenzo[5,6]azuleno[2,1,8-ija]benzo-
[f]azulen-1-yloxy)ethyl]-3-methyl-1H-imidazol-3-ium
tetrakis(tetrafluoroborate) (38, C64H78B4F16N12O6)
1-[2-(13b,13c-Diphenyl-4,8,11-tri[2-(3-methyl-1H-imidazol-
3-ium-1-yl)ethoxy]-6,13-dioxo-5,7,12,13b,13c,14-hexahydro-
5a,6a,12a,13a-tetraazabenzo[5,6]azuleno[2,1,8-ija]benzo-
[f]azulen-1-yloxy)ethyl]-3-methyl-1H-imidazol-3-ium
tetrakis(tetrafluoroborate) (34, C56H62B4F16N12O6)
The title compound was obtained according to the general
procedure starting with 24 and methyl iodide. Yield 0.21 g
1
(72%); mp 85–87ꢁC; H NMR (Acetone-d6): ꢁ ¼ 1.65–2.53
The title compound was obtained according to the general
procedure starting with 20 and methyl iodide. Yield 0.22 g
(m, 16H), 3.50–4.25 (m, 24H), 4.43 (t, J ¼ 6 Hz, 8H), 5.60 (d,
J ¼ 16 Hz, 4H), 6.65 (s, 4H), 7.20 (s, 10H), 7.58 (s, 4H), 7.70

Novel tetraimidazolium salts
645
(s, 4H), 8.90 (s, 4H) ppm; IR (KBr): ꢂꢀ¼ 1168, 1257, 1304,
References
1463, 1695, 3071 cmꢀ1
.
1. Lehn JM (1996) Comprehensive Supramoleacular Chem-
istry, vol 2. Elsevier Science Ltd., Oxford
2. Sijbesma RP, Kentgens APM, Lutz ETG, Van der Maas
JH, Nolte RJM (1993) J Am Chem Soc 115:8999
3. a) Sijbesma RP, Nolte RJM (1995) Top Curr Chem
179:25; b) Rowan AE, Elemans JAAW, Nolte RJM
(1999) Acc Chem Res 32:995
4. Reek JNH, Priem AH, Engelkamp H, Rowan AE,
Elemans JAAW, Nolte RJM (1997) J Am Chem Soc
119:9956
1-[2-(13b,13c-Dimethyl-4,8,11-tri[4-(3-methyl-1H-imidazol-
3-ium-1-yl)butoxy]-6,13-dioxo-5,7,12,13b,13c,14-hexahydro-
5a,6a,12a,13a-tetraazabenzo[5,6]azuleno[2,1,8-ija]benzo-
[f]azulen-1-yloxy)ethyl]-3-methyl-1H-imidazol-3-ium
tetrakis(tetrafluoroborate) (39, C54H74B4F16N12O6)
The title compound was obtained according to the general
procedure starting with 25 and methyl iodide. Yield 0.21 g
(79%); viscous oil; 1H NMR (Acetone-d6): ꢁ ¼ 1.60–2.45
(m, 22H), 3.60–4.25 (m, 24H), 4.33 (t, J ¼ 6 Hz, 8H), 5.38
(d, J ¼ 16 Hz, 4H), 6.58 (s, 4H), 7.49 (s, 4H), 7.59 (s, 4H),
8.87 (s, 4H) ppm; IR (KBr): 1163, 1255, 1353, 1466, 1686,
5. Kim J, Jung IS, Kim SY, Lee E, Kang JK, Sakamoto S,
Yamaguchi K, Kim K (2000) J Am Chem Soc 122:540
6. Van Numen JLM, Nolte RJM (1997) Chem Soc Perkin
Trans 2:1473
3073 cmꢀ1
.
7. Reek JNH, Kros A, Nolte RJM (1996) Chem Commun
245
8. Reek JNH, Engelkamp H, Rowan AE, Elemans JAAW,
Nolte RJM (1998) Chem Eur J 4:716
9. Elemans JAAW, de Gelder R, Rowan AE, Nolte RJM
(1998) Chem Commun:1553
1-[2-(13b,13c-Dimethyl-4,8,11-tri[6-(3-methyl-1H-imidazol-
3-ium-1-yl)hexyl]oxy-6,13-dioxo-5,7,12,13b,13c,14-hexahydro-
5a,6a,12a,13a-tetraazabenzo[5,6]azuleno[2,1,8-ija]benzo-
[f]azulen-1-yloxy)ethyl]-3-methyl-1H-imidazol-3-ium
tetrakis(tetrafluoroborate) (40, C62H90B4F16N12O6)
The title compound was obtained according to the general
procedure starting with 26 and methyl iodide. Yield 0.20 g
(69%); viscous oil; 1H NMR (Acetone-d6): ꢁ ¼ 1.10–1.95
(m, 32H), 1.78 (s, 6H), 3.50–4.40 (m, 32H), 5.37 (d,
J ¼ 16 Hz, 4H), 6.58 (s, 4H), 7.53 (s, 4H), 7.64 (s, 4H), 8.79
(s, 4H) ppm; IR (KBr): 1163, 1255, 1353, 1466, 1686,
10. Pinto MR, Kristal BM, Schanze KS (2003) Langmuir
19:6523
11. Butler AR, Leitch EJ (1980) Chem Soc Perkin Trans
2:103
12. Niele FGM, Nolte RJM (1988) J Am Chem Soc 110:172
13. Jansen K, Wego A, Buschmann HJ, Schollmeyer E,
3073 cmꢀ1
.
Dopp D (2003) Des Monomers Polym 6:43
¨