Introduction of ferrocene-containing [2]rotaxanes onto siloxane, silsesquioxane and polysiloxanes via click chemistry

Article abstract of DOI:10.1039/c2dt31406a

The reaction of N₃(CH₂)₃Si(OTMS) ₃ (TMS = SiMe₃) with a dialkylammonium having hexynyl group 1, [FcCH₂NH₂CH₂C₆H ₄-4-O(CH₂)₄CCH]PF₆ (Fc = Fe(C ₅H₄)(C₅H₅)), in the presence of dibenzo[24]crown-8-ether (DB24C8) and [Cu{Fe(CN)₄}]PF₆ catalyst yielded the [2]rotaxane containing the dialkylammonium unit terminated by a bulky silyl group. Azides with a silsesquioxane group react similarly to form the corresponding [2]rotaxanes having a bulky silsesquioxane end group. The azide-functionalized polysiloxane, [-O-SiMe{(CH₂)₃N ₃}-]_n[-O-SiMe₂-]_m also undergoes a click reaction with 1 to produce the side chain polyrotaxane. Cyclic voltammograms of these rotaxanes and 1 [(DB24C8)1] show the Fe(ii)/Fe(iii) redox at the same potential, but with different current depending on their molecular weights. Addition of PdCl₂(MeCN)₂ to a solution of the side-chain polyrotaxane forms gel which regenerates the sol upon addition of PPh₃. The Royal Society of Chemistry 2013.

Full text of DOI:10.1039/c2dt31406a

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Introduction of ferrocene-containing [2]rotaxanes onto
siloxane, silsesquioxane and polysiloxanes via click
chemistry†
Cite this: Dalton Trans., 2013, 42, 1476
Gilbert Yu, Yuji Suzaki, Tomoko Abe and Kohtaro Osakada*
The reaction of N3(CH2)3Si(OTMS)3 (TMS = SiMe3) with a dialkylammonium having hexynyl group 1,
[FcCH2NH2CH2C6H4-4-O(CH2)4CuCH]PF6 (Fc = Fe(C5H4)(C5H5)), in the presence of dibenzo[24]crown-8-
ether (DB24C8) and [Cu{Fe(CN)4}]PF6 catalyst yielded the [2]rotaxane containing the dialkylammonium
unit terminated by a bulky silyl group. Azides with a silsesquioxane group react similarly to form the cor-
responding [2]rotaxanes having a bulky silsesquioxane end group. The azide-functionalized polysiloxane,
[–O–SiMe{(CH2)3N3}–]n[–O–SiMe2–]m also undergoes a click reaction with 1 to produce the side chain
polyrotaxane. Cyclic voltammograms of these rotaxanes and 1 [(DB24C8)1] show the Fe(II)/Fe(III) redox at
the same potential, but with different current depending on their molecular weights. Addition of
PdCl2(MeCN)2 to a solution of the side-chain polyrotaxane forms gel which regenerates the sol upon
addition of PPh3.
Received 29th June 2012,
Accepted 3rd October 2012
DOI: 10.1039/c2dt31406a
www.rsc.org/dalton
particles.8 In the course of our study on ferrocene-containing
rotaxanes and polyrotaxanes as well as their photo- and elec-
Introduction
Polyrotaxanes consisting of multiple rotaxane units in the mole- trochemical properties,9 we employed Ru-catalyzed olefin
cule exhibit unique physical and photochemical properties.1 metathesis reactions and the Huisgen coupling reaction,10,11
Since the discovery of efficient synthesis of polyrotaxanes2 of as the end-capping reaction in the rotaxane synthesis.12–14 The
cyclodextrins and poly(ethylene glycol), many polyrotaxanes latter, click reaction, produces a triazole ring efficiently and is
were reported by using polymers, such as polyoxyethylene, suited for introduction of the stopper group to a pseudorotax-
polyalkene, polyarylene, and polyenes as the axle com- ane. The azide group is thus a typical functional group for the
ponent.3,4 Polysiloxanes composed of Si–O–Si bonds are also bond-making process, and a polysiloxane equipped with an
attractive macromolecules in the backbone of polyrotaxanes azide group is easily obtained from commercially available
due to “organic–inorganic hybrid” properties with their polysiloxanes. In this paper, we report the synthesis of new
thermal resistance, chemical stability, excellent electrical insu- [2]rotaxanes and a polyrotaxane containing triazole groups
lation and hydrophobicity.5,6 Rotaxane-functionalized poly- and Si-containing end groups as part of the axle components
siloxanes can be regarded also as model compounds of silica as well as formation of a polymer network by addition of a Pd
whose surfaces are functionalized with supramolecules, complex to the synthesized polyrotaxane.
although the number of reports of such rotaxanes having silox-
ane groups has been quite limited.7,8 Harada reported poly-
pseudorotaxanes type inclusion complexes of poly-
(dimethylsiloxane) and cyclodextrins.7 Stoddart and Zink
reported a reversible “molecular valve”, which has surface
attachments of bistable rotaxanes for loading and release of
guest molecules in/from the pore of mesoporous silica
Results and discussion
Scheme 1 summarizes the synthesis of the rotaxanes in this
study. End-capping of the axle component, ferrocene-contain-
ing [2]pseudorotaxane, with azides having either bulky silyl or
silsesquioxane groups yields [2]rotaxanes with the Si-contain-
ing end groups (Scheme 1A). Polyrotaxanes having silicone as
an end group are obtained similarly by using azide-functiona-
lized polysiloxane (Scheme 1B).
Dialkylammonium [FcCH2NH2CH2C6H4-4-O(CH2)4CuCH]-
PF6 (Fc = Fe(C5H4)(C5H5)) (1) reacts with N3(CH2)3Si(OTMS)3
(2a, TMS = SiMe3) in the presence of DB24C8 and [Cu{Fe-
Chemical Resources Laboratory R1-3, Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku, Yokohama 226-8503, Japan. E-mail: kosakada@res.titech.ac.jp;
Fax: +81-45-924-5224; Tel: +81-45-924-5224
†Electronic supplementary information (ESI) available: Experimental section
including synthesis of 2c and 4 as well as characterization data for compounds.
CCDC reference numbers 888102. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c2dt31406a
1476 | Dalton Trans., 2013, 42, 1476–1482
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(CN)4}]PF6 to cause a Huisgen coupling reaction of the alkynyl heptaisobutyl silsesquioxane 2b (or 2c) catalyzed by [Cu-
and alkyl azide groups to yield [(DB24C8)FcCH2NH2CH2C6H4- (MeCN)4]PF6 produces the corresponding [2]rotaxane 3b in
4-O(CH2)4(CHN3)(CH2)3Si(OTMS)3]PF6 (3a, (C5H5)) in 58% iso- 68% yield (or 3c in 63% yield). The IR peaks of 3a (3163,
lated yield (eqn (1), Ha/Hb and Ha′/Hb′ are assigned to 3a and 3083 cm−1), 3b (3168, 3079 cm−1) and 3c (3155, 3072 cm−1),
3b respectively). A similar reaction of 1 using azidepropyl- assigned to vibration of the N–H bonds, are observed at lower
wavenumbers than those of 1 (3236 and 3262 cm−1) due to the
hydrogen bonding between the ammonium and oxygen atoms
of DB24C8. The IR of 3b and 3c contain a peak of the O–Si–O
chain vibration in the silasesquioxane unit at ν = 1108 and
1106 cm−1, respectively. The HR-ESI mass spectra of 3a, 3b
and 3c show peaks at m/z 1229.5223, 1750.6672 and
1873.7478, respectively, are assigned to cationic rotaxanes
[(DB24C8)(FcCH2NH2CH2C6H4-4-O(CH2)4(C2HN3)(CH2)3R)]+.
The 1H NMR spectrum of 3a in CDCl3 shows a signal at δ 7.35,
which is assigned to the triazole hydrogen, Ha (Fig. 1a).
The 1H NMR signals of NH2, NH2CH2, Hb and SiCH2
hydrogen atoms of 3a at δ 7.21, 4.56, 2.79 and 0.44, are
observed at quite similar positions to 3b (δ 7.18 (NH2), 4.56
(NH2CH2), 2.79 (Hb′) and 0.59–0.63 (SiCH2)). The formation of
these [2]rotaxanes involves initial complexation of DB24C8 to 1
forming pseudorotaxane [(DB24C8)1]. This step is followed by
“end-capping” of the axle molecule with the siloxanes via click
Scheme 1 Synthetic strategies for [2]rotaxane-functionalized (A) siloxane and
(B) polysiloxane via “end-capping”.
reaction.15,16
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Fig. 1 1H NMR spectra of (a) 3a (in CDCl3), (b) 3b (in CDCl3) and (c) 3d (in
DMSO-d6) (400 MHz, r.t.). Asterisks indicate the residual solvent peaks (CHCl3 or
DMSO-d5).
Fig. 2 ORTEP drawing of [(DB24C8)4] (30% probability). Some of the hydro-
groups, [–O–SiMe{(CH2)3N3}–]n[–O–SiMe2–]m (2d) (n/m = 0.13/
0.87), was used as a precursor of this polyrotaxane. The reac-
tion of 2d with [(DB24C8)1], generated in situ by mixing 1 and
gen atoms, a PF6 anion and AcOEt molecule were omitted.
1
DB24C8, yielded polyrotaxane 3d (eqn (2)). H NMR spectrum
Single crystals of a model pseudorotaxane, [(DB24C8)
FcCH2NH2CH2C6H4-4-nBu]PF6 ([(DB24C8)4]), were obtained by
recrystallization from the AcOEt/CHCl3/MeOH solution con-
taining DB24C8 and [FcCH2NH2CH2C6H4-4-nBu]PF6 (4). Fig. 2
depicts the molecular structure determined by X-ray crystallo-
graphy. The ammonium hydrogens, H1 and H2, have short
contacts with oxygen atoms of DB24C8, (N1–H1⋯O2: 2.146 Å,
N1–H1⋯O3: 2.175 Å, N1–H2⋯O1: 2.342 Å, N1–H2⋯O9:
2.551 Å), via N–H⋯O hydrogen bonds. A hydrogen atom of the
cyclopentadienyl ligand, H6, forms a C–H⋯π interaction with
a C6H4 ring of DB24C8. Similar hydrogen bonds (N–H⋯Ο:
2.18–2.53 Å) and CCp–H⋯π approach (3.09 Å) were also
observed in [(DB24C8)FcCH2NH2CH2C6H4-4-Me]PF6.14a The
distance between the hydrogen H6 and the aromatic plane is
3.15 Å. The IR spectroscopy of [(DB24C8)4] shows peaks
assigned to the stretching vibration of the NH2 group at 3198
and 3065 cm−1 which are similar to those of 3a, 3b and 3c.
The end-capping reaction using a bulky silyl group was
applied to synthesis of a side chain type polyrotaxane having
polysiloxane as the main chain. The polysiloxane with azide
of 3d in DMSO-d6 contains the signals at δ 7.08 (NH2), 4.44
(NH2CH2), 2.61 (Hb′′), 0.39 (SiCH2), 0.03 (Me). The 1H NMR
spectrum of 3d shows a H NMR signal with two peaks δ 7.76
1
and 7.81 assigned to Ha′′, which may be attributed to the 1,4-
triazole groups with different chemical environment in the
polymer chain.17,18 The ratio of repeating units, SiMeO group
with the rotaxane substituent and SiMe2O group, n/m, in 3d is
estimated to be 0.16/0.84 (obtained from 1H NMR peak ratio of
SiCH2 (δ 0.39) and SiMe (δ 0.03)) and 0.18/0.82 (by elemental
analysis). The starting polymer has a Mn of 7500–10 000, while
the observed molecular weight, Mn, of 2d and 3d was esti-
mated to be Mn = 19 500 and 28 500, respectively, by GPC using
polystyrene standard. The higher molecular weight of 3d com-
pared to that of 2d corresponds to the formation of
polyrotaxane.
The Fe(II)/Fe(III) redox peaks of the ferrocenylene unit in 1
and in the axle molecule of the cationic rotaxanes (3a, 3b, 3c,
3d) were observed at similar potentials (E1/2 = 0.25–0.26 V, vs.
Ferrocenium+/Ferrocene) in MeCN (Fig. 3). The peak current,
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Fig. 3 Cyclic voltammograms of (a) 1, (b) 3a, (c) 3b and (d) 3d in MeCN ([Fe] =
1.0 mM) containing 0.10 M nBu4NPF6. Dependence of peak current, Ipa, on
molecular weights of 1, 3a, 3b, 3c and 3d are shown in the inset.
Experimental
General
[FcCH2NH2CH2C6H4-4-OCH2CH2CH2CH2CCH]PF6 (Fc
= Fe-
(C5H4)(C5H5)),13 azidepropyl-heptaisobutyl substituted silases-
quioxane (2b),23 [{SiMe(CH2CH2CH2N3)O}n{SiMe2O}m] (2d)
(n/m = 0.13/0.87)12a were prepared according to the literature
method. Anhydrous solvents were purchased and used without
further purifications. Other materials are commercially avail-
able. Chrolopropyl-heptaisobutyl substituted silasesquioxane
and poly(dimethyl)-co-(methyl-chloropropyl)-siloxane, [{SiMe-
(CH2CH2CH2Cl)O}n{Si–Me2O}m] (Mn: 7500–10 000; 14–16%
mol chloropropyl units), was purchased from Aldrich and
Gelest, respectively. 1H and 13C{1H} NMR spectra were
acquired on a Varian MERCURY-300 (300 MHz) and a Bruker
AV-400M (400 MHz). The chemical shifts were referenced with
respect to CHCl3 (δ 7.26), DMSO-d5 (δ 2.49) or CHD2CN (δ 1.93)
Ipa, decreases with increasing molecular weight of the com-
pounds, 1 (−6.8 μA), 3a (−5.3 μA), 3b (−3.7 μA), 3c (−4.3 μA)
and 3d (−2.8 μA). Dependence of peak current, Ipa, on molecu-
lar weight of compounds, 1, 3a, 3b, 3c and 3d is also shown
(Fig. 3, inset). Plot of log (|Ipa|) vs. log Mn has a linear relation-
ship as expected from the Randles–Sevcik equation and the
Mark–Houwink relationship.19 The linear relationship indi-
cates the diffusion-controlled process, in which the redox of
ferrocene units in the compounds, 1, 3a, 3b, 3c and 3d, occurs
smoothly and that rate of the reaction is limited by diffusion
of the reactants.
Addition of PdCl2(MeCN)2 (100 mM) to MeCN solution con-
taining 3d ([triazole in 3d] = 300 mM) at 20 °C converts the
polyrotaxane solution to a gel. Coordination of two or more
triazole units from different molecules to a Pd center in eqn
(3) probably formed the three-dimensional network of the
gel.13,20–22 DSC measurement (temperature range: 30 to
150 °C, scan rate: 5 °C min−1) of the gel from 3d and
PdCl2(MeCN)2 exhibited a broad irreversible endothermic peak
at 120–140 °C on heating. This can be attributed to the
removal of MeCN molecules from the gel. Further addition of
PPh3 (100 mM) to the gel regenerates the sol with low viscosity.
This result seems to suggest that the Pd-triazole bond contrib-
ute to formation of the above gel.
In summary, we achieved the synthesis of ferrocene-con-
taining [2]rotaxanes, 3a, 3b and 3c and side-chain polyrotaxane
3d by using Huisgen coupling as the end-capping reaction.
These rotaxanes have silicone, silsesquioxane and polysiloxane
units and show reversible redox owing to their ferrocenyl
groups which depends on the molecular weight of the com-
pounds. The addition of PdCl2(MeCN)2 to MeCN solution of
side-chain polyrotaxane 3d induces the gelation. Further
studies on the compounds and their further functionalization
are now in progress.
1
for H, and CDCl3 (δ 77.0), DMSO-d6 (δ 39.7) or CD3CN (δ 1.3)
for 13C as internal standards. Assignments of the signals were
supported by 1H–1H cosy, HMQC and dept135 spectra. IR
absorption spectra were recorded on Shimadzu FT/IR-8100
spectrometers. High resolution electrospray ionization mass
spectrometry (HR-ESI-MS) was recorded on a Bruker micrOTOF
II. Elemental analysis was carried out with a LECO CHNS-932
CHNS or Yanaco MT-5 CHN autorecorder. Cyclic voltammetry
(CV) was measured in MeCN solutions containing 100 mM
nBu4NPF6 with ALS electrochemical analyzer Model-600A. The
measurement was carried out in a standard one compartment
cell equipped with a Ag+/Ag reference electrode, a platinum-
wire counter electrode, and a platinum-disk working electrode.
DSC was recorded by Seiko instrument DSC6200S.
Synthesis of [(DB24C8)(FcCH2NH2CH2C6H4-4-O(CH2)4-
(C2HN3)(CH2)3Si(OSiMe3)3)]PF6 (3a). A CH2Cl2 solution
(20
mL)
containing
[FcCH2NH2CH2C6H4-4-
OCH2CH2CH2CH2CCH]PF6 (1) (725 mg, 1.14 mmol), DB24C8
(514 mg, 1.1 mmol), 2a (400 mg, 1.1 mmol) and [Cu{Fe(CN)4}]
PF6 (776 mg, 2.1 mmol) was stirred for 48 h at room tempera-
ture. The addition of the resulting mixture to Et2O cause the
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separation of 3a as a yellow solid which was collected by fil- 50.03; H, 6.86; N, 2.95%. Found: C, 49.99; H, 6.78; N, 2.85%;
tration and dried under reduced pressure (804 mg, 0.61 mmol, HR-ESI-MS (eluent: acetone); calcd for C79H129FeN4O21Si8
58%).
1750.6687; found, m/z 1750.6672 [M − PF6]+; IR (KBr disk, r.t.)
1H NMR (400 MHz, CDCl3, r.t.) δ 0.09 (s, 27H, Me), 0.44 (m, ν 3168 (N–H), 3079 (N–H), 1108 (Si–O) cm−1
.
2H, SiCH2), 1.80–1.95 (6H, SiCH2CH2, OCH2CH2CH2), 2.79 (t,
Synthesis of [(DB24C8)(FcCH2NH2CH2C6H4-4-O(CH2)4(C2-
2H, CtriazoleCH2, J = 7.4 Hz), 3.44 (m, 4H, CH2-DB24C8), 3.60 HN3)(CH2)4(C2HN3)(CH2)3(C28H63O12Si8)]PF6 (3c). A CHCl3
(m, 4H, CH2-DB24C8), 3.73 (m, 4H, CH2-DB24C8), 3.82–4.18 solution (30 mL) containing [FcCH2NH2CH2C6H4-4-
(13H, Fe(C5H4)(C5H5), CH2-DB24C8), 3.92 (m, 2H, OCH2-axle, OCH2CH2CH2CH2CCH]PF6 (1) (185 mg, 0.33 mmol), DB24C8
J = 4.4 Hz), 4.08–4.16 (6H, CH2-DB24C8, NH2CH2), 4.23 (m, 4H, (151 mg, 0.33 mmol), 2c (280 mg, 0.27 mmol) and [Cu-
CH2-DB24C8), 4.29 (t, 2H, NtriazoleCH2, J = 7.2 Hz), 4.56 (m, 2H, (MeCN)4]PF6 (220 mg, 0.89 mmol) was stirred for 48 h at
NH2CH2), 6.73 (d, 2H, C6H4-axle, J = 8.4 Hz), 6.86–6.92 (m, 4H, 50 °C. The resulting solution was fractionated between H2O
C6H4-DB24C8), 6.93–6.98 (m, 4H, C6H4-DB24C8), 7.21 (brs, and CH2Cl2/hexane and the separated organic phased was
2H, NH2), 7.31 (d, 2H, C6H4-axle, J = 8.4 Hz), 7.35 (s, 1H, dried over MgSO4, filtered and evaporated to yield crude
C2HN3) ppm; 13C{1H} NMR (100 MHz, CDCl3, r.t.) δ 1.9 (Me), product which was purified by SiO2 column chromatography
11.5 (SiCH2), 25.0 (CtriazoleCH2), 25.5 (OCH2CH2CH2 or (eluent; Et2O/CHCl3 (1/1) then CH2Cl2/CHCl3 (1/2)) to give 3c
OCH2CH2CH2), 26.1 (OCH2CH2CH2 or OCH2CH2CH2), 28.8 as yellow solid (343 mg, 0.17 mmol, 63%).
(SiCH2CH2), 48.7 (NH2CH2), 51.8 (NH2CH2), 52.7 (NtriazoleCH2),
1H NMR (400 MHz, CDCl3, r.t.) δ 0.60–0.63 (2H, SiCH2),
67.7 (OCH2-axle), 68.5 (OCH2-crown), 69.0 (C5H5), 69.4 (C5H4), 0.602 (d, 6H, SiCH2, J = 7 Hz), 0.604 (d, 6H, SiCH2, J = 7 Hz),
70.0 (C5H4), 70.4 (OCH2-crown), 70.9 (OCH2-crown), 76.3 0.946 (d, 18H, Me, J = 7 Hz), 0.954 (d, 24H, Me, J = 7 Hz),
(C5H4), 113.1 (C6H4-crown), 114.5 (C6H4-axle), 121.0 (CtriazoleH), 1.71–1.77 (m, SiCH2CH2), 1.78–1.90 (13H, SiCH2CH,
122.0 (C6H4-crown), 124.0 (C6H4-axle), 131.0 (C6H4-axle), 147.8 OCH2CH2CH2, NCH2CH2CH2), 1.93–2.03 (4H, NtriazoleCH2),
(C6H4-crown), 159.7 (C6H4-axle) ppm; Anal. Calcd for 2.75 (t, 2H, CtriazoleCH2, J = 8 Hz), 2.78 (t, 2H, CtriazoleCH2, J =
C60H93F6FeN4O12PSi4: C, 52.39; H, 6.81; N, 4.07%. Found: C, 7 Hz), 3.44 (m, 4H, CH2-DB24C8), 3.59 (m, 4H, CH2-DB24C8),
52.57; H, 6.79; N, 3.91%; HR-ESI-MS (eluent: acetone); calcd 3.73 (m, 4H, CH2-DB24C8), 3.84 (s, 5H, C5H5), 3.85 (m, 4H,
for C60H93FeN4O12Si4 1229.5213; found, m/z 1229.5223 [M − CH2-DB24C8), 3.93 (t, 2H, OCH2-axle, J = 6 Hz), 4.01–4.03 (4H,
PF6]+; IR (KBr disk, r.t.) ν 3163 (N–H), 3083 (N–H) cm−1
Synthesis of [(DB24C8)(FcCH2NH2CH2C6H4-4-O(CH2)4- 4.22 (m, 4H, CH2-DB24C8), 4.29 (t, 2H, NtriazoleCH2, J = 7 Hz),
.
C5H4), 4.10 (m, 4H, CH2-DB24C8), 4.10–4.14 (2H, NH2CH2),
(C2HN3)(CH2)3(C28H63O12Si8)]PF6 (3b). A CHCl3 solution 4.35 (t, 2H, NtriazoleCH2, J = 7 Hz), 4.57 (m, 2H, NH2CH2), 6.72
(15 mL) containing [FcCH2NH2CH2C6H4-4-OCH2CH2CH2CH2- (d, 2H, C6H4-axle, J = 8 Hz), 6.89 (m, 4H, C6H4-DB24C8), 6.95
CCH]PF6 (1) (134 mg, 0.24 mmol), DB24C8 (110 mg, (m, 4H, C6H4-DB24C8), 7.18 (brs, 2H, NH2), 7.29–7.31 (3H,
0.24 mmol), 2b (200 mg, 0.20 mmol) and [Cu-(MeCN)4]PF6 C6H4-axle, C2HN3), 7.46 (1H, s, C2HN3) ppm; 13C{1H} NMR
(150 mg, 0.40 mmol) was stirred for 48 h at 50 °C. The result- (100 MHz, CDCl3, r.t.) δ 9.2 (SiCH2CH2), 22.37 (SiCH2CH),
ing solution was fractionated between H2O and CH2Cl2 and 22.43 (SiCH2CH), 23.80 (SiCH2CH), 23.84 (SiCH2CH), 24.1
the separated organic phased was dried over MgSO4, filtered (CH2), 24.9 (CtriazoleCH2), 25.2 (CtriazoleCH2), 25.64 (Me), 25.67
and evaporated to yield crude product which was purified by (Me), 25.9 (CH2), 26.3 (CH2), 28.5 (CH2), 29.8 (NtriazoleCH2CH2),
SiO2 column chromatography (eluent; CHCl3) to give 3b as 48.5 (NH2CH2), 49.8 (NtriazoleCH2), 51.7 (NH2CH2), 52.3 (Ntriazole
-
yellow solid (251 mg, 0.14 mmol, 68%). CH2), 67.5 (OCH2-axle), 68.4 (CH2-DB24C8), 68.8 (C5H5), 69.2
1H NMR (400 MHz, CDCl3, r.t.) δ 0.59–0.63 (16H, SiCH2), (C5H4), 69.8 (C5H4), 70.2 (CH2-DB24C8), 70.7 (CH2-DB24C8),
0.93–0.96 (42H, Me), 1.78–1.89 (11H, SiCH2CH, OCH2CH2CH2), 76.2 (C5H4), 113.0 (C6H4-DB24C8), 114.4 (C6H4-axle), 120.8
1.89 (m, 2H, SiCH2CH2), 2.79 (t, 2H, CtriazoleCH2, J = 7.2 Hz), (C2HN3), 121.1 (C2HN3), 121.8 (C6H4-DB24C8), 123.8 (C6H4-
3.44 (m, 4H, CH2-DB24C8), 3.60 (m, 4H, CH2-DB24C8), 3.60 axle), 130.9 (C6H4-axle), 147.2 (C2HN3), 147.68 (C6H4-DB24C8),
(m, 4H, CH2-DB24C8), 3.73 (m, 4H, CH2-DB24C8), 3.80–4.18 147.74 (C2HN3), 159.6 (C6H4-axle) ppm; Anal. Calcd for
(21H), 4.23 (m, 4H), 4.30 (2H), 4.56 (m, 2H, NH2CH2), 6.73 (d, C85H138F6FeN7O21PSi8: C, 50.55; H, 6.89; N, 4.85%. Found: C,
2H, C6H4-axle, J = 8.8 Hz), 6.88 (m, 4H, C6H4-DB24C8), 6.95 50.51; H, 6.74; N, 4.74%; HR-ESI-MS (eluent: acetone);
(m, 4H, C6H4-DB24C8), 7.18 (brs, 2H, NH2), 7.30 (d, 2H, C6H4- calcd for C85H138FeN7O21Si8 1873.7475; found, m/z 1873.7484
axle, J = 8.8 Hz), 7.34 (s, 1H, C2HN3) ppm; 13C{1H} NMR [M − PF6]+; IR (KBr disk, r.t.) ν 3155 (N–H), 3072 (N–H), 1106
(100 MHz, CDCl3, r.t.) δ 9.3 (SiCH2), 22.4 (SiCH2), 22.5 (SiCH2), (Si–O) cm−1
23.8 (SiCH2CH), 23.9 (SiCH2CH), 24.2 (CtriazoleCH2), 25.4 Synthesis of [2]rotaxane-functionalized siloxane, [–Ο–SiMe-
.
(OCH2CH2CH2 or OCH2CH2CH2), 25.7 (2 signals, Me), 26.0 {(–CH2CH2CH2(C2HN3)(CH2)4–O–C6H4–4-CH2NH2CH2Fc)
(OCH2CH2CH2 or OCH2CH2CH2), 28.7 (CtriazoleCH2CH2), 48.5 (DB24C8)(PF6)}–]n[–Ο–SiMe2–]m (3d). A CH2Cl2 solution
(NH2CH2), 51.7 (NH2CH2), 52.3 (NtriazoleCH2), 67.5 (OCH2-axle), (20
mL)
containing
[FcCH2NH2CH2C6H4-4-
68.4 (CH2-crown), 68.8 (C5H5), 69.2 (C5H4), 69.8 (C5H4), 70.3 OCH2CH2CH2CH2CCH]PF6 (1) (280 mg, 0.51 mmol), DB24C8
(CH2-crown), 70.7 (CH2-crown), 76.2 (C5H4), 113.0 (C6H4- (306 mg, 0.68 mmol), 2d (200 mg, 0.34 mmol of N3) and [Cu
crown), 114.4 (C6H4-axle), 120.7 (C2HN3), 121.9 (C6H4-crown), (MeCN)4]PF6 (254 mg, 0.682 mmol) was stirred for 48 h at r.t.
123.9 (C2HN3), 130.9 (C6H4-axle), 147.7 (C6H4-crown), 159.6 The resulting solution was washed with water and the separ-
(C6H4-axle) ppm; Anal. Calcd for C79H129F6FeN4O21PSi8: C, ated organic phased was evaporated to yield 3d as yellow solid
1480 | Dalton Trans., 2013, 42, 1476–1482
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(372 mg, 69%). The GPC analysis in THF vs. polystyrene stan-
dard show the generation of the products with high molecular
weight (Mn = 28500, Mw/Mn = 2.32).
Rotaxanes and Knots, ed. J.-P. Sauvage and C. Dietrich-
Buchecker, Wiley-VCH, Weinheim, 1999.
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1H NMR (400 MHz, DMSO-d6, r.t.) δ 0.03 (Me), 0.39 (SiCH2),
1.61–1.82 (SiCH2CH2, OCH2CH2CH2), 2.61 (CtriazoleCH2),
3.45–4.28 (CH2-DB24C8, NH2CH2, Fe(C5H5)(C5H4), OCH2-axle,
NtriazoleCH2), 4.44 (NH2CH2), 6.61 (C6H4-axle), 6.83–6.98 (C6H4-
DB24C8), 7.08 (NH2), 7.16 (C6H4-axle), 7.76 and 7.81 (Htriazole
)
ppm; Selected 13C{1H} NMR data (100 MHz, DMSO-d6, r.t.) δ
0.7 (Me), 13.6 (SiCH2), 24.7, 47.7, 51.0, 51.6, 67.7, 68.5, 68.7,
69.7, 70.1, 76.2, 112. 6, 113.9, 121.0, 121.5, 123.7, 130.5, 147.2,
158.7 ppm; Anal. Calcd for 3d (n/m = 0.18/0.82): C, 49.85; H,
6.33; N, 3.65; N, 3.52%. Found: C, 50.03; H, 6.44; N, 3.52%; IR
(KBr disk, r.t.) ν 3163 (N–H), 3075 (N–H) cm−1
Crystal structure determination of
.
[(DB24C8)-
(FcCH2NH2CH2C6H4-4-nBu]PF6 ([(DB24C8)4]). Single crystals
of [(DB24C8)(FcCH2NH2CH2C6H4-4-nBu)]PF6 for the X-ray diffr-
action study were obtained by recrystallization from AcOEt/
CHCl3/MeOH ( = 2.0 mL/3.0 mL/2.0 mL) solution containing
[FcCH2NH2CH2C6H4-4-nBu]PF6 (4) (50 mg, 0.10 mmol) and
DB24C8 (44 mg, 0.10 mmol) at r.t. (71 mg, 6.8 × 10−2 mmol,
68%). Anal. Calcd for C46H60F6FeNO8P + H2O: C, 56.74;
H, 6.42; 1.44%. Found: C, 56.40; H, 6.42; N, 1.35%; IR (KBr
disk, r.t.) ν 3198 (N–H), 3065 (N–H), 1736 (CvO), 841 (P–F),
558 (P–F) cm−1
.
X-ray crystal structure analyses of the obtained yellow
crystal were performed at a Rigaku AFC-10R Saturn CCD diffrac-
tometer with graphite monochromated Mo-Kα radiation.
Calculations were carried out by using a program package
Crystal StructureTM for Windows.24 The crystal of [(DB24C8)
(FcCH2NH2CH2C6H4-4-nBu)]PF6 ([(DB24C8)4]) was analyzed as
AcOEt solvate.
The occupancies of the disorder atom groups, O(6)–C(43)–
C(41) and O(7)–C(44)–C(42), and C(52)–C(53) and C(51)–C(54),
were determined to be 0.51/0.49 and 0.67/0.33 respectively.
Atoms of C(51), C(52), C(53) and C(54) were refined isotropically.
K.
Osakada,
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Acknowledgements
We thank our colleagues in the Center for Advanced Materials
Analysis, Technical Department, Tokyo Institute of Technology
for HR-ESI-MS measurement and elemental analysis. This
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for Young Scientists from the Ministry of Education, Culture,
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