Clicked AC regioisomer cationic cyclodextrins for enantioseparation

Article abstract of DOI:10.1039/c4ra06279e

Novel AC regioisomer cationic cyclodextrins have been successfully prepared with azide/alkyne click chemistry. The clicked CDs were explored for the enantioseparation of acidic racemates in capillary electrophoresis.

Full text of DOI:10.1039/c4ra06279e

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COMMUNICATION
Clicked AC regioisomer cationic cyclodextrins for
enantioseparation
Cite this: RSC Adv., 2014, 4, 54512
*
Jie Zhou, Yun Liu, Yingying Lu, Jian Tang and Weihua Tang
Received 26th June 2014
Accepted 24th September 2014
DOI: 10.1039/c4ra06279e
www.rsc.org/advances
Novel AC regioisomer cationic cyclodextrins have been successfully of a clicked chiral stationary phase (CSP) for high performance
prepared with azide/alkyne click chemistry. The clicked CDs were liquid chromatography (HPLC) enantioseparations.23 Wang
explored for the enantioseparation of acidic racemates in capillary et al. also developed clicked CD-based CSP for enantiosepara-
electrophoresis.
tion in HPLC.24 A CD-derived macroporous organic polymer
monolith has also been developed via the click approach for
chiral capillary electrochromatography (CEC) and nano-LC.25
In this context, few researchers have explored the develop-
ment of clicked CD derivatives as a mobile phase for enantio-
separation in CE. In our earlier systematical work, we have
developed a library of mono-alkylimidazolium CDs and AC-
disubstituted CDs bearing both alkylimidazolium and ammo-
nium cationic sites.26–29 On the basis of practical experience, the
validation of CE methods using cationic CDs was difficult to
achieve because of the strong tendency of CDs to adsorb onto
the capillary wall, resulting in irreproducible EOF and analyte
migration times.30 Despite this drawback, the cationic CDs were
suitable for resolving acidic racemates by taking the advantage
of electrostatic interactions. Furthermore, the presence of the
imidazolium ring was demonstrated to be benecial to the
enantioseparation of dansyl amino acids because of the
formation of p–p conjunctions between the imidazole moiety of
the CDs and the aromatic moieties of the analytes.31
Chiral separations have attracted signicant attention in
academia and industry for both analytical and preparative
purposes.1,2 Capillary electrophoresis (CE) has been demon-
strated as a powerful analytical technique in the eld of phar-
maceutical,3,4 agrochemical,5 clinical and food analysis.6–10
Although the library of chiral selectors is rather large, cyclo-
dextrins (CD) and their derivatives have been considered to be
the most useful selectors in chiral CE.11,12 On the basis of
practical separations, selectively modied CD derivatives
prepared by converting hydroxyl groups to functional groups
can afford repeatable enantioseparation in run–run or batch–
batch processes.13,14 Among various CD derivatives that are
employed for chiral CE, most are functionalized through
traditional nucleophilic and electrophilic reactions with reac-
tive groups such as amino, carboxylic and sulfo groups.
However, conventional methods occasionally produce CD
derivatives with relatively low selectivity and efficiency. Click
chemistry, coined by Sharpless, is a newly demanding chemical
approach resulting in high efficiency and little or no side
products under mild reaction conditions.15 Extensive reports
have explored the copper-catalyzed azide/alkyne click reaction.
The mechanism of this ligand-free catalyzed cycloaddition
reaction was investigated by Rodionov.16 Munteanu et al. eval-
uated the regioselectivity of microwave-assisted Cu(I)-catalyzed
cycloaddition between azido and alkyne groups.17 Owing to its
advantages, this efficient method has been tremendously
employed in the elds of combinatorial chemistry,18 materials
science,19–21 and surface modication.22 In the eld of chro-
matographic applications, Zhang et al. reported the preparation
In view of the good enantioselectivities of AC regioisomer
diamino-b-cyclodextrins32 and hydroxyalkylammonium33 for the
enantioseparation of carboxylic acids, we were intrigued by the
possibility of developing efficient AC regioisomers with imida-
zolium functionality via click chemistry for the enantiosepara-
tion of amino acids. Herein, we propose the synthesis of clicked
AC regioisomer CDs for chiral recognition. The click synthesis
of 6A-2-hydroxyalkyl-1,2,3-triazole-6C-methoxyalkylimidazolium-b-
CD chloride is depicted in Scheme 1. With the clicked AC
regioisomer cationic CDs at hand, their molecular level chiral
recognition ability as chiral selectors in CE was evaluated.
As described in Scheme 1, the three-step synthesis of
disubstituted CDs started with an important AC regioisomer CD
intermediate,
6A-azido-6C-mesitylene-sulfonyl-b-cyclodextrin
Key Laboratory of So Chemistry and Functional Materials, Ministry of Education,
Nanjing University of Science and Technology, Nanjing, P. R. China. E-mail:
whtang@mail.njust.edu.cn; Fax: +86 25 8431 7311; Tel: +86 25 8431 7311
(Mess-N3-CD, 3), which was readily obtained according to our
previous protocol.27,28 A further nucleophilic addition between 3
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As summarized in Table 1, low pH led to longer elution time
because of the suppressive dissociation of silanol groups.
In the present study, a pH value of 6.0 seemed to be the best
choice for all the analytes in terms of selectivity, affording the
highest a values. For Dns-Thr, the selectivities were 1.02, 1.08
and 1.05 with increased pH buffer. Moreover, the maximum
peak resolutions were achieved at pH 6.0 for all racemates
except Dns-Aba and Dns-Nva. It is noteworthy that peak reso-
lutions were 1.7, 0.7 and 1.1 in the case of Dns-Nva.
All the analytes were well resolved under optimized condi-
tions using this CD. Consistent positive EOF was generated aer
a voltage was applied, which indicated that the triazole linkage
did not affect the orientation of the EOF even though the
linkage can be cationic charged. As shown in Table 2, the best
enantioseparations were achieved at 5 mM CD for most race-
mates. In general, the high concentrations of cationic CDs in
buffer resulted in longer elution because of the more signicant
adsorption at the interface wall of the capillary compared with
ionic or neutral CDs. For example, the elution time of Dns-Met
was only 17.2 min at 2.5 mM, while it was extended to 28.0 min
at 10 mM CD. It was exceptional that the migration time of Dns-
Ser obtained at 5 mM was slightly shorter than that at lower CD
concentrations. Compared with our previous reported AC-
dicationic CDs,27,28 this CD could realize satisfactory enantio-
separation with shorter analysis time (ca. #30 min). For most
cases, baseline separations (a > 1.01 and Rs > 1.5) were realized
at pH 6.0 though several analytes could not be resolved at
1.0 mM CD. The peak resolutions for Dns-Thr and pHyPAA
reached over 5.0 with 5.0 mM CD, whilst the selectivities were
1.01, 1.05, 1.14 and 1.03 from low to high concentration,
respectively. Dns-Phe and PCPAA were well resolved even at
1.0 mM CD. Representative electrophoretograms for selected
racemates are depicted in Fig. 2.
Scheme 1 Synthetic route of 6A-2-hydroxyethyl-1,2,3-triazole-6C-
methoxyalkylimidazolium-b-CD chlorides.
and methoxyalkylimidazole successfully introduced the imida-
zolium cation to the C6 position at the CD primary rim. A
crucial azide/alkyne 1,3-cycloaddition (click chemistry) reaction
using an organic soluble Cu catalyst afforded 6A-2-hydroxyalkyl-
1,2,3-triazole-6C-methoxyalkylimidazolium-b-CD
mesitylene
sulfonate 6 in ꢀ75% yield. The title product 7 was obtained
through anionic exchange with Amberlite (Cl) resin.
By varying the alkyl chain length of the methoxy-
alkylimidazole, two clicked AC regioisomer cationic CDs
were synthesized. All of them exhibit good enantioselectivities
towards negatively charged racemates. Herein, we took
6A-4-hydroxyethyl-1,2,3-triazole-6C-3-methoxypropylimidazolium-
b-cyclodextrin chloride (7b) as an example to illustrate the
enantioseparation capability of the synthesized CDs in chiral
CE. A series of Dns-amino acids and acidic enantiomers (see
Fig. 1) was selected as model analytes to evaluate the chiral
recognition ability of the clicked AC regioisomer CDs.
In a run of CE separation, the transportation of analytes is
primarily due to electroosmotic ow (EOF), which originates
from the electrical layer formed on the inter surface of the
capillary.34 Each sample run was performed in triplicate to
guarantee good reproducibility. Three pH values of buffer were
applied to evaluate elution behaviour changes with 5.0 mM CD.
In summary, we have explored click chemistry in the prep-
aration of AC regioisomer cationic CDs. The CDs demonstrated
moderate enantioselectivity towards ampholytic and acid race-
mates in CE. The highest selectivities and peak resolutions for
most analytes were observed with 5.0 mM CD at pH 6.0 BGEs.
Baseline enantioseparation of analytes could be achieved even
at 1.0 mM CD. Further investigations of the recognition
Table 1 Effect of buffer pH on chiral separations of selected analytes
with 5.0 mM CD
pH ¼ 5.0
Analytes t2
pH ¼ 6.0
t2
pH ¼ 7.0
t2
a
Rs
a
Rs
a
Rs
Dns-Aca 29.21 1.03 2.1 28.50 1.04 2.2
Dns-Met 24.98 1.01 1.1 24.23 1.02 1.2
Dns-Thr 27.95 1.02 1.8 26.80 1.08 5.7
Dns-Phe 24.58 1.03 2.3 23.15 1.06 2.6
Dns-Aba 24.78 1.03 2.7 23.12 1.06 2.5
19.04 1.02 1.7
20.14 1.01 1.4
19.92 1.05 3.3
18.32 1.03 1.8
16.06 1.02 1.7
16.83 1.01 1.2
16.83 1.02 1.1
Dns-Ser
31.58 1.02 1.5 29.97 1.04 1.5
Dns-Nva 26.75 1.02 1.7 24.40 1.02 0.7
pHyPAA 30.23 1.02 2.0 31.29 1.14 5.28 17.64 1.04 2.7
PCPAA
CHPAA
20.42 1.01 1.3 17.43 1.03 3.5
25.78 1.05 2.5 25.30 1.09 2.7
12.93 1.03 2.5
17.83 1.02 2.1
Fig. 1 Structures of racemic analytes used in current study.
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Table 2 Migration time (t2 minꢃ1) of the second enantiomer, selec-
tivity (a) and peak resolution (Rs) of analytes with different CD
concentrations in pH 6.0 BGEs
Methoxyalkylimidazole 2
Sodium hydride (3.0 g, 125 mmol) was added to a two neck
round-bottom ask under N2 atmosphere. Hexane was used to
remove the paraffin. DMF (30 mL) was added to dissolve sodium
hydride in an ice bath for 10 min. Then, imidazole solution
(9.2 g, 120 mmol) dissolved in DMF (30 mL) was slowly added.
Aerwards, 1-bromo-2-methoxyethane (16.68 g, 120 mmol) or 1-
bromo-3-methoxypropane (18.36 g, 120 mmol) was injected
using a syringe before overnight reuxing the reaction at 90 ꢁC.
The ltrate was extracted using CH2Cl2. The organic layer was
evaporated to yield the product as a brown liquid.
2.5 mM
Analytes t2
5 mM
10 mM
A
Rs
t2
a
Rs
t2
a
Rs
Dns-Aca 20.60 1.02 0.8
28.50 1.04 2.2 26.98 1.01 0.9
Dns-Met 17.23 1.01 0.33 24.23 1.02 1.2 28.01 1.01 0.8
Dns-Thr 24.15 1.03 0.9
Dns-Phe 19.58 1.05 1.1
Dns-Aba 22.58 1.06 1.0
26.80 1.08 5.7 26.30 1.06 2.9
23.15 1.06 2.6 20.87 1.02 2.1
23.12 1.06 2.5 25.05 1.04 1.9
29.97 1.04 1.5 31.84 1.00 0.6
24.40 1.02 0.7 28.30 1.02 0.8
31.29 1.14 5.3 30.12 1.03 1.6
17.43 1.03 3.5 21.05 1.04 2.3
25.30 1.09 2.7 24.50 1.03 1.2
Dns-Ser
29.67 1.02 0.8
Dns-Nva 18.41 1.08 2.4
pHyPAA 21.57 1.05 2.4
2-Methoxyethylimidazole 2a (11.75 g, 68.9%)
PCPAA
CHPAA
17.27 1.03 1.3
12.12 1.02 0.9
1H NMR (500 MHz, DMSO-d6) d: 8.13 (s, 1H, ]CH2im), 7.77
(s, 1H, ]CH5im), 7.62 (s, 1H, ]CH4im), 4.33 (t, 2H, –CH2-im),
3.85 (t, 2H, –CH2-OCH ), 3.30 (s, 3H, –OCH3); 13C NMR (125 MHz,
3
DMSO-d6), 131.5 (C2im), 122.9 (C4im), 126.6 (C5im), 74.1
(CH2-OCH ), 59.5 (–OCH3), 48.7 (CH2-im).
3
3-Methoxypropylimidazole 2b (13.5 g, 71.2%)
1H NMR (500 MHz, DMSO-d6) d: 8.13 (s, 1H, ]CH2im), 7.77
(s, 1H, ]CH5im), 7.64 (s, 1H, ]CH4im), 3.98 (s, 2H, –CH2-im),
3.57 (t, 2H, –CH2-OCH ), 3.30 (s, 3H, –OCH3), 1.94 (m, 2H, –CH2);
3
13C NMR (125 MHz, DMSO-d6) d: 132.8 (C2im), 122.9 (C4im),
126.6 (C5im), 68.9 (CH2-OCH ), 59.3 (–OCH3), 46.2 (CH2-im),
3
30.6 (CH2).
6A-Azido-6C-methoxyalkylimidazolium-b-cyclodextrin
mesitylene sulfonate 5
Under the protection of nitrogen, the reaction mixture of 3 (2.2
mmol, 3.0 g) and methoxyalkylimidazole (2a, 0.83 g, 6.6 mmol;
2b, 0.93 g, 6.6 mmol) in dry DMF (15 mL) was heated at 90 C
Fig.
2 Representative electrophoretograms of CE separations.
Conditions: 50 mM phosphate buffer with pH of 6.0; injection: 3.45
kPa for 5 s; voltage: 15 kV; detection: 214 nm.
ꢁ
under vigorous stirring for 2 days. Aer cooling to room
temperature, the reaction mixture was poured into acetone
(100 mL). The crude product was ltered and washed with
acetone (2 ꢂ 250 mL) before drying at 50 ꢁC under vacuum.
Aer recrystallization from water, the product 5 was obtained as
a white solid.
mechanism, especially the hydrogen bonding and p–p
conjunctions, remain to be conducted. Nevertheless, a prom-
ising approach for the exploration of clicked CD derivatives is
presented for aqueous processes such as chiral CE and catalysis.
6A-Azido-6C-2-methoxyethylimidazolium-b-cyclodextrin
mesitylene sulfonate 5a (2.78 g, 86%)
Experimental section
CE separations were performed on a P/ACE MDQ system (Full- 1H NMR (500 MHz, DMSO-d6) d: 9.13 (s, 1H, ]CH2im), 7.94
erton, CA, USA), equipped with an online photodiode array (s, 1H, ]CH5im), 7.77 (s, 1H, ]CH4im), 7.71 (s, 1H, ]CH4im),
(PDA) detector. NMR spectroscopy measurements were per- 7.34 (s, 2H, ]CH), 5.96–5.69 (m, 14H, OH-2 and OH-3), 4.95–
formed on a Bruker AVANCE 500 (500 MHz, Bruker Daltonics, 4.82 (m, 7H, H-1), 4.51–4.58 (m, 5H, OH-6), 4.21 (m, 2H,
Bremen, Germany). FT-IR characterization was achieved on a –CH2-im), 3.95 (m, 2H, CH2-OCH ), 3.64–3.49 (m, 26H, H-5, H-3
3
Bomen MB154S. All the racemates were purchased from Sigma and H-6), 3.35–3.29 (m, 14H, H-2 and H-4), 3.21 (s, 3H,
(St. Louis, MO, USA), with b-CD obtained from Tokyo Chemical –OCH3), 2.43 (s, 6H, –CH3-o-OMess), 2.17 (s, 3H, –CH3-p-OMess);
Industry (TCI, Japan). All the other chemicals were procured 13C NMR (125 MHz, DMSO-d6) 142.0 (Cipso), 136.2 (Co-OMess),
from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China) 136.1 (Cp-OMess), 129.7 (Cm-OMess), 129.51 (C2im), 122.96 (C4im),
and used without further purication unless stated. The buffers 126.61 (C5im), 101.7 (C1), 81.5 (C4), 73.3 (CH2-OCH ), 72.70 (C2),
3
for CE separation were prepared by dissolving NaH2PO4 in ultra- 72.1 (C3), 71.8 (C30), 71.6 (C5), 59.67 (C6), 59.3 (OCH3), 49.30
pure water and adjusted to the desired pH value. All mobile (CH2-im), 22.30 (CH3-o-OMess), 20.41(CH3-p-OMess). FT-IR (cmꢃ1
,
phases were freshly prepared and degassed prior to use. Mess- KBr): 3300 (O–H str), 2917 (C–H stre), 2102 (N^N str), 1670
N3-CD was prepared according to our previous report.28
(C]C str), 1367 (C–N str), 1143 (S]O str), 1012 (C–O–C stretch).
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6A-Azido-6C-3-methoxypropylimidazolium-b-cyclodextrin
mesitylene sulfonate 5b (2.8 g, 83%)
1H NMR (500 MHz, DMSO-d6) d: 9.12 (s, 1H, ]CH2im), 7.78
(s, 1H, ]CH5im), 7.72 (s, 1H, ]CH4im), 7.37 (s, 2H, ]CH), 5.94–
5.64 (m, 14H, OH-2 and OH-3), 4.97–4.79 (m, 7H, H-1), 4.63–4.57
129.7 (Cm-OMess), 137.8 (C2im), 131.5 (C–N), 130.9 (C4im), 128.4
(C5im), 123.20 (CH–N), 102.9 (C1), 84.5 (C4), 73.2 (C2), 73.00
(CH2-OCH ), 71.9 (C3), 72.6 (C5), 68.1 (C50), 60.5 (C6), 60.80
3
(CH2-OH), 48.7 (CH2-im), 27.4 (CH2-CN), 22.6 (CH3-o-OMess), 19.8
(CH3-p-OMess); FT-IR (cmꢃ1, KBr): 3311 (O–H str), 2927 (C–H str),
1643 (C]C str), 1333(C–N stre), 1161 (N]N str), 1012 (C–O–C str).
(m, 5H, OH-6), 4.21 (m, 2H, –CH2-im), 3.87 (m, 2H, CH2-OCH ),
3
3.62–3.47 (m, 26H, H-5, H-3 and H-6), 3.33–3.30 (m, 14H, H-2
and H-4), 3.22 (s, 3H, –OCH3), 2.69 (m, 2H, CH2), 2.45 (s, 6H,
–CH3-o-OMess), 2.25 (s, 3H, –CH3-p-OMess); 13C NMR (125 MHz,
DMSO-d6) d: 142.1 (Cipso), 136.4 (Co-OMess), 135.9 (Cp-OMess),
129.8 (Cm-OMess), 128.4 (C2im), 127.3 (C4im), 126.4 (C5im), 102.7
6A-4-Hydroxyethyl-1,2,3-triazole-6C-methoxyalkylimidazolium-
b-cyclodextrin chloride 7
An aqueous solution of 6a (1.0 g, 0.66 mmol) or 6b (1.0 g, 0.65
mmol) was immersed into a column lled with Amberlite IRA-
900 ion-exchange resin for 12 h. The eluent was collected and
evaporated to afford the title product 7 as a white solid.
(C1), 82.9 (C4), 73.2 (C2), 72.9(CH2-OCH ), 72.69 (C3), 68.2 (C5),
3
60.6 (CH2-OH), 60.5 (C6), 58.4 (OCH3), 48.65 (CH2-im), 29.7 (CH2),
22.8 (CH3-o-OMess), 19.5 (CH3-p-OMess); FT-IR (cmꢃ1, KBr):
3300 (O–H str), 2917 (C–H str), 2102 (N^N str), 1668 (C]C str),
1387 (C–N str), 1143 (S]O str), 1013 (C–O–C str).
6A-4-Hydroxyethyl-1,2,3-triazole-6C-2-
methoxyethylimidazolium-b-cyclodextrin chloride 7a
(0.85 g, 94%)
1H NMR (500 MHz, DMSO-d6) d: 9.11 (s, 1H, ]CH2im), 7.93 (s,
1H, ]CH), 7.77 (s, 1H, ]CH5im), 7.71 (s, 1H, ]CH4im), 5.96–
5.69 (m, 14H, OH-2 and OH-3), 4.95–4.82 (m, 7H, H-1), 4.58–4.51
6A-4-Hydroxyethyl-1,2,3-triazole-6C-methoxyalkylimidazolium-
b-cyclodextrin mesitylene sulfonate 6
A mixture of 5 (5a, 1.45 g, 1.0 mmol; 5b, 1.48 g, 1.0 mmol),
cuprous iodide triphenylphosphine (60 mg, 0.1 mmol), 3-butyn-
1-ol (0.076 mL, 1.2 mmol) and DMF (15 mL) was reuxed at 90
ꢁC for 1 day. The reaction mixture was poured into acetone to
precipitate the crude product. The title product 6 was recrys-
tallized two times from water to afford a white solid.
(m, 5H, OH-6), 4.21 (m, 2H, –CH2-im), 3.95 (m, 2H, CH2-OCH ),
3
3.64–3.49 (m, 26H, H-5, H-3 and H-6), 3.35–3.29 (m, 14H, H-2
and H-4), 3.21 (s, 3H, –OCH3), 2.88 (t, 2H, CH2-OH), 2.74–2.72
(t, 2H, CH2); 13C NMR (125 MHz, DMSO-d6) d: 137.8 (C2im), 131.5
(C–N), 130.7 (C4im), 128.4 (C5im), 123.2 (]CH–N), 102.9 (C1),
83.6 (C4), 73.2 (C2), 73.0 (CH2-OCH ), 71.9 (C3), 72.5 (C5), 68.1
3
6A-4-Hydroxyethyl-1,2,3-triazole-6C-2-methoxyethylimidazolium-b-
cyclodextrin mesitylene sulfonate 6a (1.2 g, 79%)
1H NMR (500 MHz, DMSO-d6) d: 9.11 (s, 1H, ]CH2im), 7.93 (s, 1H,
]CH), 7.77 (s, 1H, ]CH5im), 7.71 (s, 1H, ]CH4im), 7.37 (s, 2H,
CHben), 6.02–5.74 (m, 14H, OH-2 and OH-3), 5.04–4.82 (m, 7H, H-
1), 4.58–4.51 (m, 5H, OH-6), 4.21 (m, 2H, –CH2-im), 3.95 (m, 2H,
(C50), 60.8 (CH2-OH) 60.52 (C6), 58.5 (OCH3), 48.6 (CH2-im), 29.7
(CH2-CN); IR (cmꢃ1, KBr): 3311 (O–H str), 2927 (C–H str), 1637
(C]C str), 1333 (C–N str), 1157 (N]N str), 1020 (C–O–C str).
6A-4-Hydroxyethyl-1,2,3-triazole-6C-3-methoxypropylimidazolium-
b-cyclodextrin chloride 7b (0.8 g, 90%)
CH2-OCH ), 3.64–3.49 (m, 26H, H-5, H-3 and H-6), 3.35–3.23 (m,
1H NMR (500 MHz, DMSO-d6) d: 9.12 (s, 1H, ]CH2im), 7.93 (s,
1H, ]CH), 7.78 (s, 1H, ]CH5im), 7.72 (s, 1H, ]CH4im), 5.94–
5.64 (m, 14H, OH-2 and OH-3), 4.97–4.79 (m, 7H, H-1), 4.63–4.57
3
14H, H-2 and H-4), 3.17 (s, 3H, –OCH3), 2.88 (t, 2H, CH2-OH), 2.74–
2.72 (t, 2H, CH2), 2.40 (s, 6H, –CH3-o-OMess), 2.25 (s, 3H,
–CH3-p-OMess); 13C NMR (125 MHz, DMSO-d6) d: 142.0 (Cipso),136.2
(Co-OMess), 136.0 (Cp-OMess), 129.7 (Cmeta-OMess), 137.8 (]C2im),
131.50 (C–N), 130.70 (]C4im), 128.44 (]C5im), 123.2 (CH–N),
(m, 5H, OH-6), 4.23 (m, 2H, –CH2-im), 3.97 (m, 2H, CH2-OCH ),
3
3.64–3.50 (m, 26H, H-5, H-3 and H-6), 3.36–3.30 (m, 14H, H-2
and H-4), 3.25 (s, 3H, –OCH3), 2.89 (t, 2H, CH2-OH), 2.74–2.72
(t, 2H, CH2), 2.65 (m, 2H, CH2); 13C NMR (125 MHz, DMSO-d6) d:
137.4 (C2im), 131.5 (C–N), 130.7 (C4im), 128.4 (C5im), 123.7
102.9 (C1), 83.9 (C4), 73.2 (C2), 73.0 (CH2-OCH ), 71.9 (C3), 72.6
3
(C5), 68.1 (C50), 60.5 (C6), 60.8 (CH2-OH), 58.5 (OCH3),
48.65 (CH2-im), 29.70 (CH2-CN), 22.3 (CH3-ortho-OMess), 20.4
(CH3-para-OMess); FT-IR (cmꢃ1, KBr): 3311 (O–H str), 2927 (C–H str),
1637 (C]C str), 1333 (C–N str), 1157 (N]N str),1020 (C–O–C str).
(]CH–N), 102.7 (C1), 83.9 (C4), 73.2 (C2), 73.1 (CH2-OCH ), 72.69
3
(C3), 68.2 (C5), 60.6 (CH2-OH), 60.5 (C6), 58.4 (OCH3), 48.65
(CH2-im), 30.6 (CH2-CN), 29.7 (CH2); FT-IR (cmꢃ1, KBr): 3311
(O–H str), 2927 (C–H str), 1643 (C]C str), 1333 (C–N str), 1161
(N]N str), 1012 (C–O–C str).
6A-4-Hydroxyethyl-1,2,3-triazole-6C-2-methoxyethylimidazolium-
b-cyclodextrin mesitylene sulfonate 6b (1.2 g, 75%)
1H NMR (500 MHz, DMSO-d6) d: 9.12 (s, 1H, ]CH2im), 7.94
(s, 1H, ]CH), 7.78 (s, 1H, ]CH5im), 7.72 (s, 1H, ]CH4im), 7.33
(s, 2H, CHben), 6.01–5.73 (m, 14H, OH-2 and OH-3), 5.16–4.98
(m, 7H, H-1), 4.58–4.51 (m, 5H, OH-6), 4.21 (m, 2H, –CH2-im),
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