Carbamate-linked (oligo)phenothiazines in mesoporous silica by post-synthetic grafting: Fluorescent redox-active hybrid materials

Article abstract of DOI:10.1002/ejoc.200900332

Mesoporous hybrid, materials of (oligo)phenothiazmes cova-lently grafted onto MCM-41 or SBA-15 silica have been readily prepared from (oligo)phenothiazinyl carbamates. The phenothiazine precursors show interesting electronic proper-ties according to elect

Full text of DOI:10.1002/ejoc.200900332

FULL PAPER
DOI: 10.1002/ejoc.200900332
Carbamate-Linked (Oligo)phenothiazines in Mesoporous Silica by
Post-Synthetic Grafting: Fluorescent Redox-Active Hybrid Materials
Adam W. Franz,[a] Zhou Zhou,[b] Raluca Turdean,[a] Alex Wagener,[b] Biprajit Sarkar,[c]
Martin Hartmann,[d] Stefan Ernst,[b] Werner R. Thiel,*[b] and Thomas J. J. Müller*[a]
Keywords: Cyclic voltammetry / Fluorescence / Heterocycles / Mesoporous materials / Radical ions
Mesoporous hybrid materials of (oligo)phenothiazines cova-
lently grafted onto MCM-41 or SBA-15 silica have been
readily prepared from (oligo)phenothiazinyl carbamates. The
phenothiazine precursors show interesting electronic proper-
ties according to electronic spectroscopy and cyclic voltam-
metry. The resulting electronically active hybrid materials
display fluorescence and can be oxidized to give stable radi-
cal-cationic species upon mild oxidation.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
Introduction
Mesoporous silica materials[1] contain regular and well-
ordered pores with very high specific surfaces (1000 m2/g)
that can be chemically modified through the reaction of the
Si–OH bonds present in the cavities.[2] As intriguing host
structures for functional molecules their applications in-
clude nanoscale chemistry and physics,[3] optical and mag-
netic materials,[4] catalysis,[5] and even functional materials
and molecular machines.[6] Particularly important for the
development of functional materials are electronically
active entities as mesoporous hosts are not only transparent
to visible light, but they can also stabilize reactive redox or
photoexcited intermediates. Of the redox-active heterocy-
cles, phenothiazines,[7] tricyclic nitrogen- and sulfur-con-
taining heterocycles that are well-established due to a broad
spectrum of pharmacological activity,[8] possess particularly
interesting properties. Owing to their low oxidation poten-
tials, they readily form stable radical cations by reversible
one-electron oxidations (Scheme 1) and some of their physi-
ological activity can be attributed to this type of reactiv-
ity.[9]
Scheme 1.
Furthermore, the radical cations give rise to a fingerprint
of characteristic, deep-colored absorptions.[7,10] As spectro-
scopic probes, phenothiazine derivatives have found entry
into molecular and supramolecular arrangements for pho-
toinduced electron transfer (PET) studies[11] and as motifs
in organic materials.[12] The inherent adsorption of pheno-
thiazines on silica surfaces is quite small[13] and does not
lead to irreversible anchorage. EPR studies of photo-oxid-
ized phenothiazines adsorbed on porous silica have shown
that radical cations are formed and presumably the silica
framework acts as an electron acceptor. This property has
been applied in a sensor system for the analysis of redox
enzymes in which phenothiazines serve as electron shuttles.
Interestingly, phenothiazines covalently bound to silica or
mesoporous silica have not been reported prior to our stud-
ies. Just recently, we disclosed a proof of principle for the
incorporation of functionalized phenothiazines in mesopo-
rous MCM-41 by post-synthetic grafting.[14]
As part of our program to synthesize and investigate
(oligo)phenothiazinyl-based molecular wires,[15] we have
communicated the syntheses, structures, and first cyclic vol-
tammetry measurements of directly linked phenothiazinyl
dyads, triads,[16] and oligomers,[17] which can be regarded as
models for polymer-based coupled electrophores. Herein,
we report on the syntheses and properties of various carb-
amate-based phenothiazines and (oligo)phenothiazines,
that is higher oligomers of phenothiazines, and the synthe-
[a] Institut für Organische Chemie und Makromolekulare Chemie,
Heinrich-Heine-Universität Düsseldorf,
Universitätsstraße 1, 40225 Düsseldorf, Germany
Fax: +49-211-81-14324
E-mail: ThomasJJ.Mueller@uni-duesseldorf.de
[b] Fachbereich Chemie, Technische Universität Kaiserslautern,
Erwin-Schrödinger-Str., 67661 Kaiserslautern, Germany
E-mail: thiel@chemie.uni-kl.de
[c] Institut für Anorganische Chemie, Universität Stuttgart,
Pfaffenwaldring 55, 70569 Stuttgart, Germany
[d] ECRC – Erlangen Catalysis Resource Center, Friedrich-Alexan-
der-Universität Erlangen–Nürnberg,
Egerlandstraße 3, 91058 Erlangen, Germany
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.200900332.
Eur. J. Org. Chem. 2009, 3895–3905
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3895

W. R. Thiel, T. J. J. Müller et al.
FULL PAPER
ses and properties of novel redox-active structured hybrid
materials by covalently grafting these electrochromophores
onto mesoporous silica.
Results and Discussion
Synthesis of Phenothiazinyl Building Blocks
Carbamates are synthetically accessible by straightfor-
ward addition of an alcohol to an isocyanate. The major
advantage of this approach lies in its highly atom-economic
use of both starting materials. The reaction proceeds with-
out the formation of any byproducts. Therefore, the retro-
synthetic analysis for carbamate-based phenothiazinyl and
(oligo)phenothiazinyl building blocks for incorporation
into mesoporous silica suggests carbamate formation from
a phenothiazinyl-substituted alcohol with a commercially
available triethoxysilyl-functionalized isocyanate (Scheme 2).
The alcohol in turn can be prepared by reduction of the
corresponding carbonyl compound.
Scheme 3. Synthesis of phenothiazinylcarbonyl compounds.
Scheme 2. Retrosynthetic analysis of carbamate-based (oligo)-
phenothiazinyl building blocks.
Phenothiazinyl aldehydes 1a and 1b (n = 0) are easily
prepared by Vilsmeier formylation of 10-methyl- or 10-n-
hexylphenothiazine and ketone 2 is obtained by alkylation
of the commercially available 2-acetylphenothiazine
(Scheme 3). For aldehydes with extended π conjugation, Su-
zuki cross-coupling is the most favorable, mild, and
straightforward access to functionalized phenothiazines.
Therefore, one-pot borylation–coupling of bromopheno-
thiazines 3[18] with 7-bromo-10-n-hexylphenothiazine-3-car-
baldehyde (4) or the coupling of 3a with p-formylphenyl-
boronic acid (5) leads to the aldehydes 1c, 1d, and 6 in
moderate-to-good yields.
Scheme 4. Reduction of (oligo)phenothiazinylcarbonyl compounds
1, 2, and 6 with LiAlH4 to the corresponding alcohols 7, 8, and 9.
3896
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3895–3905

Carbamate-Linked (Oligo)phenothiazines in Mesoporous Silica
By standard reduction with lithium aluminium hy- phenothiazine cores in the individual molecules. The first
dride[19] in diethyl ether at reflux the carbonyl compounds oxidation potentials stemming from the most electron-rich
1, 2, and 6 provide the corresponding alcohols 7, 8, and 9 phenothiazine core are found to range from E00/+1 = 542 mV
in good yields (Scheme 4). With these alcohols in hand the (terphenothiazine 11d) to E00/+1 = 768 mV (monophenothi-
stage is set for the introduction of the triethoxysilane linker azine 11a).
by isocyanate addition.
Table 1. Selected absorption and emission spectral[a] and cyclovol-
tammetric data for compounds 11–13.
Reaction of the alcohols 7, 8, and 9 with 3-(triethoxy-
silyl)propyl isocyanate (10)[20] in dry 1,4-dioxane or neat at
Com-
pound
Absorption
λmax,abs [nm] λmax,em [nm]
Emission
Stokes shift
˜
E00/+1 E0+1/+2 E0+2/+3
70 °C under argon and in the presence of dibutyltin dilaur-
ate (DBTL) as catalyst gave the desired carbamates 11–13
in quantitative yields (Scheme 5). The structures of the car-
bamates were unambiguously confirmed by 1H and 13C
NMR spectroscopy, mass spectrometry, and combustion
analyses or high-resolution mass spectrometry.
∆ν[c] [cm–1]
[mV] [mV]
[mV]
11a
11b
11c
11d
12
312, 290, 258
314, 260
366, 322, 268
373, 324, 270 474, 514 (sh)
322, 268, 240
312, 260
465
441
461
10500
9500
5600
5700
9600
10000
768
735
729
542
669
734
–
–
893
710
–
–
–
–
827
–
–
467
453
13
–
[a] Recorded in CH2Cl2, T = 20 °C. [b] Recorded in CH2Cl2, T =
–
20 °C, v = 100 mV/s, electrolyte: nBu4N+ PF6 , Pt working elec-
trode, Pt counter electrode, Ag/AgCl reference electrode. [c] ∆ν =
˜
λmax,abs – λmax,em [cm–1].
Synthesis of Mesoporous Hybrid Materials
The carbamate linker is sufficiently stable to allow post-
synthetic grafting of the electrophore units in toluene onto
MCM-41 or SBA-15 under reflux conditions. Unreacted
precursors were removed by Soxhlet extraction with dichlo-
romethane and the organic/inorganic hybrid materials ob-
tained [(oligo)phenothiazine@MCM-41 or (oligo)phenothi-
azine@SBA-15] are denoted as 14–16 (Scheme 6, Table 2).
To probe the size effect of different (oligo)phenothiazine
units in detail, the functionalized MCM-41 materials were
prepared under the same conditions. Elemental analyses
showed that the loading of MCM-41 with phenothiazines
varies (14a Ͼ 14b Ͼ 16 Ͼ 15 Ͼ 14c). We attribute these
differences to variations in the molecular size of the organic
unit. In particular, in the case of the biphenothiazine 11c,
only traces of nitrogen (ca. 0.1%) could be detected by ele-
mental analysis. In addition, TG-DTA analysis exhibited
only 1.8% mass loss in the temperature range of 300–
600 °C, which corresponds to a grafting of 0.03 mmol/g of
Scheme 5. Synthesis of (oligo)phenothiazinecarbamates 11–13.
Electronic Properties of the Carbamates 11–13
The electronic properties of the (oligo)phenothiazine-
carbamates 11–13 were investigated by absorption and
emission spectroscopy and by cyclic voltammetry (Table 1).
Most characteristically, for all the carbamates, the absorp-
tion in the UV region is accompanied by an intense blue-
to-greenish blue fluorescence. The emission maxima lie be-
tween 441 and 474 nm. The Stokes shifts are quite remark-
able and lie in the range ∆ν = 5600–10500 cm–1. Substantial
˜
Stokes shifts have also been observed for many other phe-
nothiazine derivatives[15,16] and can be attributed to signifi-
cant geometrical changes upon excitation from a highly
nonplanar ground state to a largely planar excited state.[21]
The electrochemical data for the phenothiazines prepared
in this work were obtained by cyclic voltammetry in the
anodic region (up to 1.2 V). For all the compounds revers-
Scheme 6. Mesoporous hybrid materials obtained by post-synthetic
ible oxidation steps are found, which reflects the number of grafting onto MCM-41 or SBA-15.
Eur. J. Org. Chem. 2009, 3895–3905
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3897

W. R. Thiel, T. J. J. Müller et al.
FULL PAPER
Table 2. The textural parameters of parent MCM-41, SBA-15, 14, 15, and 16 derived from nitrogen adsorption/desorption analysis and
the content of loaded phenothiazines in the hybrid materials.
Sample
Substrate
BET surface area
[m2 g–1]
Pore volume
[cm3 g–1]
Pore diameter
Content of phenothiazine[a]
[Å]
[mmolg–1]
[wt.-%]
Neat MCM-41
Neat SBA-15
MCM-41
MCM-41
MCM-41
SBA-15
SBA-15
MCM-41
MCM-41
1092
1101
814
846
996
806
716
935
903
0.95
1.58
0.62
0.68
0.90
1.19
0.96
0.80
0.72
28
65
23
23
28
60
56
26
23
–
–
–
–
14a
14b
14c
14c*
14d
15
0.41
0.34
0.03[b]
0.32
0.17
0.24
0.30
15.5
15.3
1.8[b]
23.4
17.2
12.6
13.9
16
[a] Calculated according to the content of nitrogen (CHN elemental analysis). [b] Calculated from the data of a TG-DTG analysis (weight
loss from 300–600 °C).
11c onto MCM-41. The molecular size of 11c was estimated
by molecular modeling to be about 2.9 nm, which is larger
than the mean pore size of the substrate MCM-41 (2.8 nm).
This size effect may hinder the diffusion of 11c into the
pore channels during the post-synthetic grafting process.
Therefore, only the “outer” surface of the support is decor-
ated with the redox-active organic substrate. We thus used
SBA-15 as the support for the grafting of the phenothiazine
dyad 11c and the even larger triad 11d. SBA-15 possesses
the same mesostructure as MCM-41, but provides a rela-
tively large medium pore diameter (6.5 nm in our case).
This led in the case of 14c* (SBA-15) to a significant in-
crease in the loading with respect to 14c (MCM-41).
Structural Properties of the Mesoporous Hybrid Materials
The powder XRD patterns of extracted neat MCM-41
and 14a–c, 15, and 16 are shown in Figure 1A; those of
samples 14c* and 14d together with neat SBA-15 are pre-
sented in Figure 1B. Neat MCM-41 shows four Bragg re-
flections from the (100), (110), (200), and (210) planes,
which can be indexed to a two-dimensional (2D) hexagonal
p6mm symmetry and indicate a highly ordered hexagonal
structure. Neat SBA-15 is characterized by three reflections
Figure 1. A: Powder XRD patterns of (a) parent MCM-41, (b) 14a,
(c) 14b, (d) 14c, (e) 15, and (f) 16; B: powder XRD patterns of
(g) parent SBA-15, (h) 14c*, and (i) 14d.
from the (100), (110), and (200) planes in the 2θ range of cylindrical channels.[24] SBA-15 displays a distinct hysteresis
0.8–2°, which can also be indexed to a hexagonal cell. After loop (type H1) and a sharp increase in the adsorption at
modification, all the samples still exhibit the first- [(100)] higher P/P0 values (0.65), which indicates a uniform meso-
and second-order reflections [(110) and (200)], which indi- structure with large pores.[25] The pore size distribution
cates the structural preservation of the materials. The lower curves of the neat supports and the hybrid samples are illus-
intensities of the modified samples in comparison with the trated in Figure S1 of the Supporting Information). The
neat materials can be attributed to a diminished mesostruc- volumes and pore sizes were calculated by using the Bar-
tural order and/or to a reduced scattering contrast between rett–Joyner–Halenda (BJH) method and the specific surface
the silica wall and the porous system.[22]
areas were obtained by Brunauer–Emmett–Teller (BET)
Nitrogen sorption was used to follow the changes in the treatment of the isotherm. The phenothiazine contents of
pore structure that result from modification of the surface the materials are given in Table 2. Clearly the specific sur-
by the grafting of the organic compounds. The specific sur- face areas, the pore sizes, and the pore volumes of all the
face areas and the textural properties of neat MCM-41, hybrid materials are smaller than those of neat MCM-41
SBA-15, and all hybrid samples are summarized in Table 2. and SBA-15 due to the presence of the organic fragments
Both parent mesoporous substrates exhibit type IV iso- in the pore channels.[26] However, the type IV isotherms and
therms, which is typical of periodic mesoporous materials the narrow pore size distributions are maintained in all the
(Figure 2, A and B).[23] The isotherm of MCM-41 shows no modified samples proving the ordering of the mesoporous
hysteresis, which indicates a uniform pore size and ordered structures of these materials.
3898
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3895–3905

Carbamate-Linked (Oligo)phenothiazines in Mesoporous Silica
IR and NMR Investigations
FTIR spectroscopy was used to provide information on
the organic modifications of the silica systems. The IR spec-
tra of all the hybrid materials are shown in Figure 3, except
sample 14c. In this case the characteristic absorptions of
the organic group could not be observed due to the small
amount of organic species in the material. For comparison,
the spectra of neat MCM-41 and SBA-15 are presented in
Figure S2 of the Supporting Information. The broad band
in the range of 3600–3200 cm–1 can be assigned to the O–
H stretching absorption of bonded internal Si–OH groups.
The band at around 1100 cm–1 is attributed to the asymmet-
ric Si–O–Si vibration, and the peak at 800 cm–1 to the sym-
metric Si–O–Si vibration. Absorptions at 950 and 460 cm–1
can be assigned to the bending vibrations of the surface
silanols and Si–O, respectively.[27] In addition to these
bands, which characterize the bulk SiO2 material, the an-
choring of the organic groups can be proved by the presence
of aliphatic CH stretching (3000–2700 cm–1) and defor-
mation vibrations (1470 cm–1).[28] Furthermore, typical
peaks of C=O carbamate stretching vibrations are observed
at about 1700 cm–1 These findings confirm the introduction
of carbamate-linked phenothiazine molecules in the meso-
porous supports.
Figure 3. FTIR spectra of (a) 14a, (b) 14b, (c) 14c*, (d) 14d, (e) 15,
and (f) 16.
vide information on the resonances in the solution 13C{1H}
NMR spectrum of 11c. The strong peak at δ = 8 ppm can
be assigned to the C–Si unit, which demonstrates that this
bond is not cleaved during the grafting process. The over-
lapping resonances between δ = 20 and 40 ppm are due to
the presence of alkyl groups. The peaks in the aromatic re-
gion can be assigned to the electron-rich phenothiazine
core. Compared with the spectrum in solution, a small
downfield shift of the carbon resonance of the C=O group
is observed, which can be assigned to an interaction be-
tween the carbonyl group and Brønsted/Lewis acidic sur-
face sites.[14]
The successful introduction and covalent ligation of the
phenothiazine components were additionally verified by so-
lid-state 13C CP-MAS NMR spectroscopy. All the hybrid
materials show solid-state 13C NMR spectra similar to
those of the corresponding free phenothiazines. Figure 4, as
an example, shows the spectrum of 14c*; the red lines pro-
Figure 4. 13C CP-MAS NMR spectra of 14c*; the lines give infor-
mation on the resonances in the solution NMR spectra of 11c.
Optical Properties of the Hybrid Materials
All the phenothiazine-containing hybrid materials show
several strong absorptions in the ultraviolet region (Fig-
ure 5, solid lines, and Table S4 of the Supporting Infor-
mation). These are similar to the absorptions of the pure
organic compounds (see Table 1). A slight redshift of the
peak maxima can be observed by increasing the number of
phenothiazine cores or by linking a phenyl group to the
phenothiazine site. On the basis of the absorption spectra of
the hybrid materials it can be postulated that the interaction
between the phenothiazine moieties and the silica frame-
work is only weak. The slight band-broadening in the spec-
tra of incorporated phenothiazine molecules compared with
the pure organic compounds in solution may be attributed
to weak π-electron interactions with surface hydroxy
groups. This phenomenon is often observed for aromatic
chromophores adsorbed on silica materials.[29]
Figure 2. A: N2 adsorption/desorption isotherms of (a) neat
MCM-41, (b) 14a, (c) 14b, (d) 14c, (e) 15, and (f) 16; B: N2 adsorp-
tion/desorption isotherms of (g) neat SBA-15, (h) 14c*, and (i) 14d
(adsorption points are marked by solid symbols and desorption
points by empty symbols).
Eur. J. Org. Chem. 2009, 3895–3905
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3899

W. R. Thiel, T. J. J. Müller et al.
FULL PAPER
precursor carbamates 11–13. This dual emission is either
caused by conformational biases as a consequence of re-
stricted molecular rotation and relaxation inside the pores
or by population of TICT (twisted intramolecular charge
transfer) states.[30]
Detection of Stable Phenothiazine Radical Cations in the
Materials
Phenothiazines in MCM-41 or SBA-15 form stable radi-
cal cations upon treatment with oxidizing agents
(Scheme 7). The oxidation of phenothiazine was carried out
with the one-electron acceptor antimony pentachloride in a
dichloromethane suspension, leaving SbCl6– as the counter-
ion.[31] For the materials 14a, 14b, and 16, functionalized
with monophenothiazine, a color change to red was ob-
served during the oxidation reaction (Figure 5, middle in-
set). This color change is manifested by an absorption band
at around 515 nm, which is typical of a phenothiazine radi-
cal cation (see parts a,b,d in Figure 5).[32] In contrast, oxi-
dation of the (oligo)phenothiazine functionalized materials
14c, 14c*, and 14d furnished greenish products with absorp-
tion spectra that are different to those of the monopheno-
thiazine radical cations. This result indicates besides pheno-
thiazine radical cations the presence of di- and even tri-
cationic species as a consequence of the oxidation of (oligo)-
phenothiazines.[33,34] Therefore, we assigned the broad ab-
sorption band in the Vis/NIR region to intramolecular
charge-transfer (CT) bands. Furthermore, because the oxi-
dation of phenothiazine moieties results in a considerable
structural change, from the butterfly conformation of the
native neutral form to the planar radical cation,[21] intermo-
lecular interactions between the native and oxidized pheno-
thiazine moieties within the pores can also be expected.
Hence, the observed solid-state UV/Vis spectra of the oxid-
ized materials 17–19 represent a superposition of intra- and
intermolecular electronic interactions, which accounts for
the formation of intensely colored materials. Note that the
resulting deeply colored materials 17–19 preserve their
color and thus the radical-cation nature of the oxidized hy-
Figure 5. UV/Vis absorption spectra of modified samples of
(a) 14a, (b) 14b, (c) 14c, (d) 16, (e) 14c*, (f) 14d, and (g) 15 (solid
lines), the absorptions of the corresponding radical-cation samples
17a, 17b, 17c, 19, 17c*, 17d, and 18 (dotted lines), and the emission
spectra of modified samples (dashed lines). The inset in the middle
exhibits the different colors of the solid products after oxidation.
The inset in the bottom panel shows the color change caused by
the oxidation of 14c* in suspension and in the solid state.
The photoluminescence spectra of the hybrid materials
are also shown in Figure 5 (dashed lines). Similar to the
corresponding purely organic precursors, the hybrid materi-
als show emission at about 440–470 nm. Only sample 15
reveals a pronounced bathochromic shift of the emission
maximum relative to its precursor 12; a similar effect was
observed in the absorption spectra of 15. At the moment
there is only speculation on this finding: 12 is the largest
phenothiazine that could be introduced into the narrow
pores of MCM-41. Interaction of the π system with the
walls of the support may cause an increase in the parallel
orientation of the phenyl ring and the phenothiazine moiety
and thus lead to a redshift of the absorption and emission.
In addition, for 14b, 14c, and 16, besides the expected max-
ima at around 430 nm, additional maxima at 390 nm can
be observed, which are absent in the solution spectra of the Scheme 7. Oxidation of mesoporous phenothiazinyl hybrids.
3900 Eur. J. Org. Chem. 2009, 3895–3905
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Carbamate-Linked (Oligo)phenothiazines in Mesoporous Silica
Universität, Düsseldorf, Germany, and the Fachbereich Chemie,
Technische Universität Kaiserslautern.
brid materials for weeks at ambient temperature when
stored under nitrogen.
The existence of stable phenothiazine radical cations in
the hybrid materials was additionally confirmed by EPR
spectroscopy. The EPR spectrum of 15 is shown as an ex-
Electrochemistry: Cyclic voltammetry experiments (EG & G po-
tentiostatic instrumentation) were performed under argon in dry
and degassed CH2Cl2 at room temperature and at scan rates of
ample in Figure 6 (the spectra of 14c* and 14d are shown 100, 250, 500, and 1000 mV/s. The electrolyte was Bu4NPF6
(0.025 ). The working electrode was a 1 mm platinum disk, the
counter-electrode was a platinum wire, and the reference electrode
was a Ag/AgCl electrode. The potentials were corrected to the in-
in the Supporting Information) and reveals a g value of
2.0051. Because the EPR signal is not resolved, hyperfine
coupling constants and anisotropic g tensors could not be
determined. However, the high symmetry of the EPR spec-
trum indicates that the phenothiazine radicals are in an iso-
tropic environment in the hybrid materials.
ternal standard of ferrocene/ferrocenium in CH2Cl2 (E00/+1
=
450 mV).[39]
Characterization of the Hybrid Materials: The loading of the silica
samples with organic groups was calculated from the nitrogen con-
tent of the elemental analysis obtained with a Carlo–Erba (model
EA 1108) Elemental Analyzer. Thermogravimetric and differential
thermogravimetric analyses (TG-DTG) were carried out with a
Rheometric Scientific STA 1500 analyzer using an alumina pan in
air and by heating from ambient temperature to 800 °C at a heating
rate of 5 °C/min. Powder X-ray diffraction (PXRD) patterns of the
solid samples were obtained with a Siemens D5005 diffractometer
with Cu-Kα radiation (λ = 1.5404 Å, 30 kV, 30 mA). N2 adsorption/
desorption isotherms were measured at 77 K with a Quantachrome
Autosorb 1 sorption analyzer after evacuating the samples at a tem-
perature of 120 °C for 12 h. The specific surface areas were calcu-
lated from the BET equation by using the adsorption data obtained
in the low relative pressure range of 0.04–0.2 and the pore size
distribution curves were obtained from the desorption branch by
the BJH method. The infrared spectra (KBr) were recorded using
Figure 6. Q-band EPR spectrum of 15 at 297 K.
a Jasco FT/IR-6100 spectrometer. Proton-decoupled solid-state 13
C
Conclusions
and 29Si CP-MAS NMR spectra were obtained with a Bruker DSX
Avance spectrometer at resonance frequencies of 100.6 and
79.5 MHz, respectively. UV/Vis diffuse reflectance spectra were re-
corded with a Perkin–Elmer Lambda-18 spectrophotometer with
neat MCM-41 or SBA-15 as the background standard. Q-band
CW EPR experiments were performed at 297 K with a Bruker
EMX 10–40 spectrometer.
A series of novel hybrid organic/inorganic mesoporous
silica materials have been synthesized by covalently grafting
carbamate-linked (oligo)phenothiazines onto MCM-41 or
SBA-15. The molecular precursors display fluorescence and
low oxidation potentials, that is, they possess favorable elec-
tronic properties for electronically active materials. Highly
ordered hexagonal mesoporous structures were confirmed
by XRD and N2 adsorption measurements. 13C CP-MAS
NMR and FTIR data show the successful incorporation of
the organic species into the solid materials. The existence
of stable phenothiazine radical cations in the materials is
clearly observed by UV/Vis and EPR spectroscopy. Further
2-Acetyl-10-hexyl-10H-phenothiazine (2): 2-Acetyl-10H-phenothi-
azine (9.61 g, 40 mmol) was dissolved in dry THF (100 mL), potas-
sium tert-butoxide (4.71 g, 42 mmol) was added, and the solution
was stirred at room temp. for 1 h. Then 1-bromohexane (10.2 mL,
72 mmol) was slowly added dropwise to the reaction mixture and
the stirring was continued at 70 °C for 16 h. The dark solution
was cooled to room temp and diluted with dichloromethane. The
studies towards increasing the phenothiazine content in the solution was washed with water and sodium sulfite solution, the
organic layer was dried with magnesium sulfate, and the solvents
were removed in vacuo. The residue was purified by chromatog-
raphy on silica gel (hexane/acetone, 15:1) to give 8.01 g (62%) of 2
pores and elucidating the properties of the novel hybrid sys-
tems are underway in our laboratories.
1
as an orange oil. Rf (hexane/acetone, 5:1) = 0.45. H NMR ([D6]-
acetone, 300 MHz): δ = 0.77 (t, J = 7.1 Hz, 3 H), 1.21 (m, 4 H),
1.34 (m, 2 H), 1.68 (m, 2 H), 2.43 (s, 3 H), 3.78 (t, J = 7.1 Hz, 2
H), 6.80 (m, 2 H), 6.99 (dd, J = 7.5, 1.5 Hz, 1 H), 7.07 (m, 2 H),
7.34 (m, 2 H) ppm. 13C NMR ([D6]acetone, 75 MHz): δ = 14.2
(CH3), 23.0 (CH2), 26.8 (CH3), 26.9 (CH2), 27.0 (CH2), 31.8 (CH2),
47.9 (CH2), 114.3 (CH), 116.2 (CH), 123.0 (CH), 123.2 (CH), 123.9
(Cquat), 125.0 (Cquat), 127.3 (CH), 127.6 (CH), 128.0 (CH), 136.8
Experimental Section
General: Reagents, catalysts, and solvents were purchased reagent
grade and used without further purification. THF, diethyl ether,
and 1,4-dioxane were dried and distilled according to standard pro-
cedures.[35] Phenothiazinecarbaldehyde 1 was prepared according
to procedures published in the literature.[36,37] Column chromatog-
raphy: silica gel 60, mesh 70–230. TLC: silica gel plates. 1H and
13C NMR spectra: CD2Cl2, CDCl3, and [D6]acetone (referenced to
Me4Si).[38] The assignments of quaternary C, CH, CH2, and CH3
were made by using DEPT spectroscopy. Elemental analyses were
carried out in the Microanalytical Laboratories of the Organisch-
Chemisches Institut, Ruprecht-Karls-Universität, Heidelberg, Ger-
many, the Institut für Pharmazeutische Chemie, Heinrich-Heine-
(Cquat), 145.0 (Cquat), 145.9 (Cquat), 197.4 (Cquat) ppm. IR (film): ν
˜
= 2955, 2929, 2856, 1680, 1592, 1559, 1463, 1444, 1378, 1357, 1324,
1275, 1226, 1132, 1108, 921, 810, 750, 636 cm–1. UV/Vis (CH2Cl2):
λmax (ε) = 246 (22600), 282 (22600), 374 (1500 L/molcm) nm. MS
(FAB+): m/z (%) = 325.3 (100) [M]+, 254.2 (19) [M – C5H11]+, 240.2
(15) [M – C6H13]+. C20H23NOS (325.3): calcd. C 73.53, H 7.24, N
4.39, S 9.49; found C 73.81, H 7.12, N 4.30, S 9.85.
Eur. J. Org. Chem. 2009, 3895–3905
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3901

W. R. Thiel, T. J. J. Müller et al.
FULL PAPER
4-(10-Hexyl-10H-phenothiazin-3-yl)benzaldehyde (6): A solution of
3-bromo-10-hexyl-10H-phenothiazine (3a; 1.83 g, 5.06 mmol), 4-
formylphenylboronic acid (5; 630 mg, 4.21 mmol), potassium car-
bonate (1.74 g, 12.6 mmol), and tetrakis(triphenylphosphane)palla-
dium (190 mg, 0.16 mmol) in a degassed mixture of dimethoxye-
thane (28 mL) and distilled water (14 mL) was stirred at reflux for
14 h under argon. After cooling to room temperature, a solution
of sodium sulfite and water was added to the reaction mixture.
The aqueous layer was washed several times with small portions
of dichloromethane, the combined organic layers were dried with
magnesium sulfate, and the solvents were removed in vacuo. The
residue was purified by chromatography on silica gel (hexane/di-
6.69–6.80 (m, 3 H), 6.97–7.06 (m, 4 H) ppm. 13C NMR (CD2Cl2,
75 MHz): δ = 14.6 (CH3), 23.4 (CH2), 27.3 (CH2), 27.6 (CH2), 32.2
(CH2), 48.1 (CH2), 65.0 (CH2), 116.1 (CH), 116.2 (CH), 123.0
(CH), 125.0 (Cquat), 125.6 (Cquat), 126.8 (CH), 126.9 (CH), 128.0
(CH), 136.1 (Cquat), 145.4 (Cquat), 146.0 (Cquat) ppm. IR (film): ν
˜
= 3346, 2954, 2827, 2855, 1577, 1496, 1467, 1444, 1362, 1333, 1287,
1244, 1040, 1011, 814, 747 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 260
(3700), 314 (7100 L/molcm) nm. MS (EI+): m/z (%) = 313.1 (92)
[M]+, 242.1 (78) [M – C5H11]+, 228.1 (100) [M – C6H11]+, 210.1
(35). C19H23NOS (313.5): calcd. C 72.80, H 7.40, N 4.47; found C
72.53, H 7.45, N 4.44.
(10,10Ј-Dihexyl-10H,10ЈH-3,3Ј-biphenothiazin-7-yl)methanol (7c):
According to GP1 and after chromatography on silica gel (hexane/
diethyl ether, 3:1) the alcohol 7c (415 mg, 76%) was isolated as
a yellow oil. Rf (hexane/acetone, 5:1) = 0.13. 1H NMR (CD2Cl2,
500 MHz): δ = 0.88 (t, J = 7.0 Hz, 6 H), 1.32 (m, 8 H), 1.44 (m, 4
H), 1.79 (m, 4 H), 3.85 (t, J = 7.0 Hz, 4 H), 4.54 (s, 2 H), 6.85 (d,
J = 8.0 Hz, 1 H), 6.90 (m, 4 H), 7.14 (m, 4 H), 7.30 (m, 2 H), 7.32
(dd, J = 2.0, J = 8.0 Hz, 2 H) ppm. 13C NMR (CD2Cl2, 125 MHz):
δ = 13.4 (2 C, CH3), 22.3 (2 C, CH2), 26.3 (2 C, CH2), 26.5 (2 C,
CH2), 31.1 (2 C, CH2), 47.1 (2 C, CH2), 64.0 (CH2), 114.9 (CH),
115.0 (CH), 115.1 (CH), 115.2 (CH), 121.9 (CH), 123.9 (Cquat),
124.0 (Cquat), 124.5 (2 C, CH), 124.7 (Cquat), 124.8 (2 C, CH), 125.7
(CH), 125.8 (CH), 126.9 (2 C, CH), 133.7 (2 C, Cquat), 135.1 (2 C,
Cquat), 143.8 (Cquat), 143.9 (Cquat), 144.0 (Cquat), 144.8 (Cquat) ppm.
1
ethyl ether, 10:1) to give 860 mg (43%) of 6 as an orange resin. H
NMR ([D6]acetone, 300 MHz): δ = 0.83 (t, J = 6.9 Hz, 3 H), 1.28
(m, 4 H), 1.45 (m, 2 H), 1.79 (m, 2 H), 3.95 (t, J = 7.0 Hz, 2 H),
6.97–7.22 (m, 4 H), 7.40–7.66 (m, 3 H), 7.81 (d, J = 8.3 Hz, 2 H),
7.94 (d, J = 8.3 Hz, 2 H), 10.03 (s, 1 H) ppm. 13C NMR ([D6]-
acetone, 75 MHz): δ = 14.2 (CH3), 23.2 (CH2), 27.1 (CH2), 27.5
(CH2), 32.1 (CH2), 47.9 (CH2), 116.7 (CH), 116.9 (CH), 123.5
(CH), 124.8 (Cquat), 126.4 (CH), 127.2 (CH), 127.5 (CH), 128.1
(CH), 128.4 (CH), 129.1 (CH), 129.8 (CH), 129.9 (CH), 130.4
(CH), 130.9 (CH), 134.3 (Cquat), 136.2 (Cquat), 145.6 (Cquat), 146.2
(Cquat), 146.6 (Cquat), 192.3 (CH) ppm. IR (film): ν = 2954, 2930,
˜
1696, 1602, 1574, 1465, 1444, 1362, 1334, 1251, 1214, 1171, 810,
749 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 252 (28800), 282 (2900), 302
(1900), 376 (1100 L/molcm) nm. MS (FAB+): m/z (%) = 387.3 (100)
[M]+, 358.3 (3) [M – CHO]+, 302.2 (22) [M – C6H13]+. C25H25NOS
(387.5): calcd. C 77.48, H 6.50, N 3.61; found C 77.05, H 6.61, N
3.50.
IR (KBr): ν = 2954, 2928, 1630, 1460, 1414, 1384, 1333, 1251, 1106,
˜
873, 808, 747 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 270 (52400), 324
(19200), 364 (12200 L/molcm) nm. MS (FAB+): m/z (%) = 594.4
(100) [M]+, 577.4 (37) [M – OH]+, 523.3 (16) [M – C5H11]+, 509.3
(32) [M – C6H13]+, 424.2 (30) [M – 2C6H13]+, 407.2 (32) [M –
General Procedure for the Reduction of Phenothiazinyl-Substituted
Carbonyl Compounds 1, 2, and 6 with Lithium Aluminium Hydride 2C6H13
– – 2C6H13 –
OH]+, 394.2 (14) [M CH2OH]+.
(GP1): A solution of the phenothiazinyl-substituted carbonyl com-
pound 1, 2, or 6 (1 equiv.) in dry diethyl ether (30 mL per equiv. of
carbonyl compound) was slowly added through a dropping funnel
to a well-stirred mixture of lithium aluminium hydride (2.0 equiv.)
in dry diethyl ether (20 mL per equiv. of LiAlH4) heated to 40 °C
over 20–30 min. The reaction mixture was stirred at 40 °C for 16 h
and was then cooled to 0 °C. Then water (50 mL) and diluted hy-
drochloric acid (10 mL) were added. The aqueous phase was
washed with small portions of diethyl ether, the combined organic
phases were dried with magnesium sulfate, and the solvents were
removed in vacuo. The residue was purified by chromatography on
silica gel to furnish the pure phenothiazinyl-substituted alcohols 7,
8, or 9 as solids or oils.
C37H42N2OS2·0.3CH2Cl2 (594.3 + 25.2): calcd. C 72.33, H 6.93, N
4.52; found C 72.30, H 6.74, N 4.52.
[10,10Ј-Dihexyl-7Ј-(10-hexyl-10H-phenothiazin-3-yl)-10H,10ЈH-
3,3Ј-biphenothiazin-7-yl]methanol (7d): According to GP1 and after
chromatography on silica gel (hexane/diethyl ether, 3:1) the alcohol
7d (152 mg, 61%) was isolated as a yellow oil. Rf (hexane/acetone,
1
5:1) = 0.13. H NMR (CD2Cl2, 500 MHz): δ = 0.88 (m, 9 H), 1.32
(m, 12 H), 1.44 (m, 6 H), 1.80 (m, 6 H), 3.85 (t, J = 7.0 Hz, 6 H),
4.54 (s, 2 H), 6.89 (m, 7 H), 7.14 (m, 4 H), 7.32 (m, 8 H) ppm. 13C
NMR (CD2Cl2, 125 MHz): δ = 13.4 (3 C, CH3), 22.3 (3 C, CH2),
26.2 (3 C, CH2), 26.5 (3 C, CH2), 31.1 (3 C, CH2), 47.1 (3 C, CH2),
64.0 (CH2), 114.9 (CH), 115.0 (CH), 115.1 (CH), 115.2 (CH), 121.9
(CH), 123.8 (Cquat), 124.0 (Cquat), 124.2 (Cquat), 124.5 (2 C, CH),
124.7 (CH), 124.8 (2 C, CH), 125.7 (CH), 125.8 (2 C, CH), 126.9
(3 C, CH), 133.6 (3 C, Cquat), 135.1 (3 C, Cquat), 143.9 (3 C, Cquat),
(10-Methyl-10H-phenothiazin-3-yl)methanol (7a): According to
GP1 and after chromatography on silica gel (hexane/diethyl ether,
5:1) the alcohol 7a (604 mg, 84%) was isolated as light-yellow need-
les, m.p. 132–133 °C. Rf (hexane/acetone, 5:1) = 0.08. 1H NMR
144.8 (Cquat) ppm. IR (KBr): ν = 2924, 2853, 1701, 1604, 1458,
˜
1376, 1330, 1239, 1104, 1039, 872, 805, 745 cm–1. UV/Vis (CH2Cl2):
(CD2Cl2, 300 MHz): δ = 3.27 (s, 3 H), 4.46 (s, 2 H), 6.74 (m, 2 H), λmax (ε) = 270 (24600), 324 (10600), 368 (8500 L/mol cm) nm.
6.85 (dt, J = 1.0, J = 7.5 Hz, 1 H), 7.05 (m, 3 H), 7.13 (m, 1 HRMS (MALDI-TOF): calcd. for 875.398; found 875.300.
H) ppm. 13C NMR (CD2Cl2, 75 MHz): δ = 35.6 (CH3), 64.7 (CH2), C37H42N2OS2·0.3 CH2Cl2 (594.3 + 25.2): calcd. C 72.33, H 6.93,
114.4 (CH), 114.5 (CH), 122.8 (CH), 123.4 (Cquat), 123.8 (Cquat),
126.2 (CH), 126.7 (CH), 127.3 (CH), 127.9 (CH), 135.9 (Cquat),
145.6 (Cquat), 146.2 (Cquat) ppm. MS (FAB+): m/z (%) = 243.2 (100)
[M]+, 228.2 (14) [M – CH3]+, 226.2 (22), 213.2 (11) [M –
CH2OH]+. C14H13NOS (243.3): calcd. C 69.11, H 5.39, N 5.76, S
13.18; found C 68.88, H 5.31, N 5.46, S 12.94.
N 4.52; found C 72.30, H 6.74, N 4.52.
[4-(10-Hexyl-10H-phenothiazin-3-yl)phenyl]methanol (8): According
to GP1 and after chromatography on silica gel (hexane/diethyl
ether, 4:1) the alcohol 8 (620 mg, 71%) was isolated as a yellow oil.
1H NMR ([D6]acetone, 300 MHz): δ = 0.86 (t, J = 7.1 Hz, 3 H),
1.27–1.42 (m, 4 H), 1.44 (m, 2 H), 1.80 (m, 2 H), 3.95 (t, J = 7.0 Hz,
2 H), 4.31 (t, J = 5.8 Hz, 1 H), 4.67 (d, J = 5.6 Hz, 2 H), 6.92–7.00
(m, 3 H), 7.14–7.23 (m, 2 H), 7.42 (dd, J = 2.6, J = 3.6 Hz, 3 H),
7.47 (dd, J = 2.2, J = 2.2 Hz, 1 H), 7.58 (d, J = 8.3 Hz, 2 H) ppm.
(10-Hexyl-10H-phenothiazin-3-yl)methanol (7b): According to GP1
and after chromatography on silica gel (hexane/diethyl ether, 4:1)
the alcohol 7b (770 mg, 77%) was isolated as a yellow oil. 1H NMR
(CD2Cl2, 300 MHz): δ = 0.76 (t, J = 7.0 Hz, 3 H), 1.15–1.35 (m, 6 13C NMR ([D6]acetone, 75 MHz): δ = 14.2 (CH3), 23.2 (CH2), 27.1
H), 1.60–1.70 (m, 2 H), 3.70 (t, J = 7.3 Hz, 2 H), 4.37 (br., 2 H),
(CH2), 27.5 (CH2), 32.1 (CH2), 47.9 (CH2), 116.7 (CH), 116.9
3902
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3895–3905

Carbamate-Linked (Oligo)phenothiazines in Mesoporous Silica
(CH), 123.5 (CH), 124.8 (Cquat), 126.4 (CH), 127.2 (CH), 127.5 H), 1.29–1.45 (m, 6 H), 1.60 (m, 2 H), 1.77 (m, 2 H), 3.13 (m, 2
(CH), 128.1 (CH), 128.4 (CH), 129.1 (CH), 129.8 (CH), 129.9 H), 3.80 (m, 6 H), 4.95 (br., 2 H), 5.17 (br., 1 H), 6.81–6.92 (m, 3
(CH), 130.4 (CH), 130.9 (CH), 134.3 (Cquat), 136.2 (Cquat), 145.6
H), 7.09–7.17 (m, 4 H) ppm. 13C NMR (CD2Cl2, 75 MHz): δ = 7.8
(CH2), 14.0 (CH3), 18.4 (CH3), 22.9 (CH2), 23.6 (CH2), 26.8 (CH2),
27.0 (CH2), 31.7 (CH2), 43.8 (CH2), 47.7 (CH2), 58.6 (CH2), 65.9
(Cquat), 146.2 (Cquat), 146.6 (Cquat) ppm. IR (film): ν = 3332, 2953,
˜
2928, 2856, 1601, 1576, 1491, 1459, 1364, 1250, 1193, 1039, 1011,
810, 787, 748 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 240 (18100), 270 (CH2), 115.4 (CH), 115.7 (CH), 122.6 (CH), 124.7 (Cquat), 125.1
(33300), 324 (8300 L/molcm) nm. MS (EI+): m/z (%) = 389.2 (56)
[M]+, 318.2 (40) [M – C5H11]+, 304.1 (100) [M – C6H13]+, 286.1
(28), 274.1 (20). C25H27NOS (389.5): calcd. C 77.08, H 6.99, N
3.60; found C 77.21, H 7.21, N 3.59.
(Cquat), 127.4 (CH), 127.5 (CH), 127.6 (CH), 127.6 (CH), 131.4
(Cquat), 145.4 (Cquat), 145.5 (Cquat), 156.5 (Cquat) ppm. IR (film): ν
˜
= 2972, 2928, 2886, 1722, 1529, 1466, 1333, 1243, 1166, 1104, 1080,
958, 777, 749 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 260 (31100), 314
(5100 L/molcm) nm. MS (EI+): m/z (%) = 560.3 (82) [M]+, 296.1
( 3 8) , 2 4 7 . 1 (1 00 ), 20 2. 0 ( 46 ). HR MS (E I) : c al cd . for
C29H44N2O5SSi 560.2740; found 560.2759.
1-(10-Hexyl-10H-phenothiazin-2-yl)ethanol (9): According to GP1
and after chromatography on silica gel (hexane/diethyl ether, 1:1,
then 2-propanol/hexane, 1:1) the alcohol 9 (3.84 g, 76%) was iso-
lated as a yellow oil. Rf (hexane/acetone, 5:1) = 0.37. 1H NMR
(CD2Cl2, 300 MHz): δ = 0.87 (m, 3 H), 1.30 (m, 3 H), 1.45 (m, 6
H), 1.78 (m, 2 H), 3.86 (t, J = 7.2 Hz, 2 H), 4.81 (q, J = 6.4 Hz, 1
H), 6.87 (m, 1 H), 6.91 (m, 3 H), 7.06 (m, 1 H), 7.10 (m, 1 H), 7.16
(m, 1 H) ppm. 13C NMR (CD2Cl2, 75 MHz): δ = 14.1 (CH3), 22.9
(CH2), 25.5 (CH3), 26.9 (CH2), 27.2 (CH2), 31.8 (CH2), 47.6 (CH2),
70.3 (CH), 113.0 (CH), 115.8 (CH), 119.6 (CH), 122.6 (CH), 123.9
(Cquat), 125.2 (Cquat), 127.4 (CH), 127.5 (2 C, CH), 145.7 (Cquat),
(10,10Ј-Dihexyl-10H,10ЈH-3,3Ј-biphenothiazin-7-yl)methyl 3-(Tri-
ethoxysilyl)propylcarbamate (11c): According to GP2 (with dioxane
as solvent) and after drying at 10–3 mbar for 1 d the carbamate
1
11c (2.40 g, 99%) was isolated as a brown oil. H NMR (CD2Cl2,
500 MHz): δ = 0.59 (t, J = 8.0 Hz, 2 H), 0.88 (t, J = 7.0 Hz, 6 H),
1.19 (t, J = 7.0 Hz, 9 H), 1.32 (m, 8 H), 1.44 (m, 4 H), 1.60 (m, 2
H), 1.80 (m, 4 H), 3.14 (q, J = 6.5 Hz, 2 H), 3.79 (q, J = 7.0 Hz, 6
H), 4.94 (s, 2 H), 5.17 (br., 1 H), 6.84 (d, J = 6.5 Hz, 1 H), 6.90
(m, 4 H), 7.14 (m, 4 H), 7.29 (m, 2 H), 7.33 (dd, J = 2.0, J =
6.5 Hz, 2 H) ppm. 13C NMR (CD2Cl2, 125 MHz): δ = 7.2 (CH2),
13.4 (CH3), 17.8 (CH3), 22.3 (CH2), 23.0 (CH2), 26.3 (CH2), 26.4
(CH2), 26.5 (CH2), 31.1 (CH2), 43.1 (CH2), 47.1 (CH2), 58.0 (CH2),
66.7 (CH2), 114.7 (CH), 115.0 (CH), 115.2 (CH), 121.9 (CH), 123.9
(Cquat), 124.5 (CH), 124.7 (CH), 124.8 (CH), 126.8 (CH), 126.9
(CH), 127.0 (CH), 127.1 (CH), 130.8 (Cquat), 133.6 (Cquat), 133.8
(Cquat), 143.6 (Cquat), 143.9 (Cquat), 144.5 (Cquat), 144.8 (Cquat),
145.9 (Cquat), 146.1 (Cquat) ppm. IR (film): ν = 3430, 3063, 2959,
˜
2928, 2856, 1706, 1596, 1586, 1572, 1464, 1444, 1421, 1366, 1321,
1288, 1252, 1239, 749 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 258
(33700), 312 (5600 L/molcm) nm. MS (EI+): m/z (%) = 327.1 (100)
[M]+, 256.1 (68) [M – C5H11]+, 242.0 (76) [M – C6H13]+.
C20H25NOS (327.3): calcd. C 73.35, H 7.69, N 4.28, S 9.79; found
C 73.04, H 7.78, N 4.15, S 9.44.
General Procedure for the Synthesis of the Phenothiazinyl-Substi-
tuted Carbamates 11–13 from the Phenothiazinyl-Substituted
Alcohols 7–9 with 3-(Triethoxysilyl)propyl Isocyanate (GP2): The
phenothiazinyl-substituted alcohol 7, 8, or 9 (1.0 equiv.), 3-(trieth-
oxysilyl)propyl isocyanate (10; 1.0 equiv.), and dibutyltin dilaurate
(DBTL; 0.002 equiv.) were placed under argon in a screw-capped
pressure vessel. In some cases dry 1,4-dioxane was added as a sol-
vent. The mixture was stirred at 70 °C for 16 h. After drying in
vacuo the phenothiazinyl-substituted carbamates 11–13 were iso-
lated as viscous oils.
155.3 (Cquat), 155.8 (Cquat) ppm. IR (film): ν = 3423, 2926, 1719,
˜
1638, 1509, 1459, 1332, 1212, 1077, 747 cm–1. UV/Vis (CH2Cl2):
λmax (qual.) = 268, 322, 366. HRMS (MALDI): calcd. for
C47H63N3O5S2Si 841.398; found 841.427. C47H63N3O5S2Si·
2C4H8O2 (841.3 + 176.1): calcd. C 64.86, H 7.82, N 4.13; found C
64.45, H 8.02, N 4.25.
[10,10Ј-Dihexyl-7Ј-(10-hexyl-10H-phenothiazin-3-yl)-10H,10ЈH-
3,3Ј-biphenothiazin-7-yl]methyl 3-(Triethoxysilyl)propylcarbamate
(11d): According to GP2 (with dioxane as solvent) and after drying
at 10–3 mbar for 1 d the carbamate 11d (2.40 g, 99%) was isolated
(10-Methyl-10H-phenothiazin-3-yl)methyl 3-(Triethoxysilyl)propyl-
carbamate (11a): According to GP2 (without solvent) and after
drying at 10–3 mbar for 1 d the carbamate 11a (970 mg, 99%) was
isolated as a dark-yellow oil. 1H NMR (CD2Cl2, 300 MHz): δ =
0.58 (t, J = 8.1 Hz, 2 H), 1.18 (t, J = 7.2 Hz, 9 H), 1.57 (m, 2 H),
3.12 (m, 2 H), 3.34 (s, 3 H), 3.77 (q, J = 7.1 Hz, 6 H), 4.94 (s, 2
H), 6.78 (m, 1 H), 6.82 (dd, J = 0.9, J = 7.8 Hz, 1 H), 6.92 (dt, J =
1.2, J = 7.5 Hz, 1 H), 7.09–7.20 (m, 4 H) ppm. 13C NMR (CD2Cl2,
75 MHz): δ = 7.8 (CH2), 18.4 (CH3), 23.6 (CH2), 35.5 (CH3), 43.8
(CH2), 58.6 (CH2), 65.9 (CH2), 114.2 (CH), 114.4 (CH), 122.7
(CH), 123.3 (Cquat), 123.7 (Cquat), 127.2 (CH), 127.3 (CH), 127.8
(2 C, CH), 131.5 (Cquat), 145.9 (2 C, Cquat), 156.5 (Cquat) ppm. IR
1
as a brown oil. H NMR (CD2Cl2, 500 MHz): δ = 0.60 (m, 2 H),
0.88 (m, 9 H), 1.20 (t, J = 7.0 Hz, 9 H), 1.31 (m, 12 H), 1.42 (m,
6 H), 1.58 (m, 2 H), 1.80 (m, 6 H), 3.11 (m, 2 H), 3.82 (q, J =
7.0 Hz, 6 H), 3.86 (m, 6 H), 4.95 (s, 2 H), 6.84 (m, 1 H), 6.89 (m,
6 H), 7.13 (m, 4 H), 7.32 (m, 8 H) ppm. 13C NMR (CD2Cl2,
125 MHz): δ = 7.2 (CH2), 13.4 (CH3), 14.1 (CH3), 17.8 (CH3), 22.3
(CH2), 23.0 (CH2), 23.4 (CH2), 26.3 (CH2), 26.4 (CH2), 26.5 (CH2),
31.1 (CH2), 42.6 (CH2), 47.1 (CH2), 47.2 (CH2), 58.0 (CH2), 66.7
(CH2), 114.7 (CH), 115.0 (CH), 115.1 (CH), 115.2 (CH), 121.9
(CH), 123.9 (Cquat), 124.0 (Cquat), 124.2 (Cquat), 124.5 (CH), 124.7
(Cquat), 124.8 (CH), 126.8 (CH), 126.9 (CH), 127.1 (CH), 130.8
(Cquat), 133.6 (Cquat), 133.7 (Cquat), 143.6 (Cquat), 143.7 (Cquat),
143.9 (Cquat), 144.5 (Cquat), 144.8 (Cquat), 157.7 (Cquat) ppm. IR
(film): ν = 3341, 2973, 2927, 2886, 1720, 1528, 1467, 1444, 1333,
˜
1250, 1165, 1104, 1080, 958, 812, 776, 752 cm–1. UV/Vis (CH2Cl2):
λmax (ε) = 258 (42000), 290 (6300), 312 (7000 L/molcm) nm. MS
(EI+): m/z (%) = 490.2 (100) [M]+, 226.1 (46). HRMS (EI+): calcd.
f o r C 2 4 H 3 4 N 2 O 5 S S i 4 9 0 . 1 9 5 8 ; f o u n d 4 9 0 . 1 9 5 6 .
C24H34N2O5SSi·0.2C10H21NO4Si (490.3 + 49.5): calcd. C 57.81, H
7.13, N 5.70; found C 57.74, H 7.09, N 5.62.
(film): ν = 3367, 2928, 1719, 1561, 1459, 1414, 1388, 1333, 1213,
˜
1195, 1079, 957, 874, 805 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 270
(9600), 324 (3900), 373 (3100 L/mol cm) nm. HRMS (MALDI):
calcd. for C65H82N4O5S3Si 1122.522; found 1122.533.
4-(10-Hexyl-10H-phenothiazin-3-yl)benzyl 3-(Triethoxysilyl)propyl-
carbamate (12): According to GP2 (without solvent) and after dry-
ing at 10–3 mbar for 1 d the carbamate 12 (724 mg, 99%) was iso-
(10-Hexyl-10H-phenothiazin-3-yl)methyl 3-(Triethoxysilyl)propyl-
carbamate (11b): According to GP2 (without solvent) and after
drying at 10–3 mbar for 1 d the carbamate 11b (1.09 g, 99%) was
1
lated as a yellow resin. H NMR (CD2Cl2, 300 MHz): δ = 0.60 (t,
1
isolated as a yellow oil. H NMR (CD2Cl2, 300 MHz): δ = 0.60 (t,
J = 6.9 Hz, 2 H), 0.87 (t, J = 7.0 Hz, 3 H), 1.19 (t, J = 7.0 Hz, 9
J = 7.8 Hz, 2 H), 0.88 (t, J = 7.1 Hz, 3 H), 1.21 (t, J = 7.0 Hz, 9 H), 1.30–1.47 (m, 6 H), 1.60 (m, 2 H), 1.80 (m, 2 H), 3.16 (m, 2
Eur. J. Org. Chem. 2009, 3895–3905
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3903

W. R. Thiel, T. J. J. Müller et al.
FULL PAPER
H), 3.79 (m, 8 H), 5.08 (br., 2 H), 5.31 (s, 1 H), 6.91 (t, J = 9.2 Hz,
for the synthesis of the samples 14a, 14b, 14c, 14c*, 15, and 16, the
3 H), 7.11–7.19 (m, 2 H), 7.38 (m, 4 H), 7.53 (d, J = 8.2 Hz) ppm. silica precursor (1.0 g) was heated for 24 h at reflux under nitrogen
13C NMR (CD2Cl2, 75 MHz): δ = 7.84 (CH2), 14.0 (CH3), 18.4 with the appropriate phenothiazine (ca. 1.0 mmol) in dry toluene
(CH3), 22.9 (CH2), 23.6 (CH2), 26.9 (CH2), 27.1 (CH2), 31.7 (CH2), (50 mL). The resulting solid was filtered and washed with toluene
43.8 (CH2), 47.7 (CH2), 58.6 (CH2), 66.2 (CH2), 115.7 (CH), 115.8 and dichloromethane. Subsequently it was subjected to Soxhlet ex-
(CH), 122.6 (CH), 124.5 (Cquat), 125.4 (Cquat), 125.7 (CH), 126.1
traction for 24 h under nitrogen with dichloromethane as the sol-
(CH), 126.6 (CH), 127.5 (CH), 127.6 (CH), 128.7 (CH), 135.0 vent. After being dried under a vacuum at room temperature, the
(Cquat), 136.1 (Cquat), 139.8 (Cquat), 144.9 (Cquat), 145.3 (Cquat), products 14a, 14b, 14c, and 16 were obtained as white powders
156.5 (Cquat) ppm. IR (film): ν = 3400, 2954, 2928, 2871, 1700,
and the products 14c* and 15 as yellow powders. Sample 14d was
˜
1535, 1492, 1464, 1279, 1251, 1195, 1105, 1017, 810, 793, 748 cm–1. prepared by a similar procedure except that the amount of 11d was
UV/Vis (CH2Cl2): λmax (ε) = 240 (144900), 268 (23900), 322
(6400 L/mol cm) nm. MS (FAB+): m/z (%) = 636.3 (100) [M]+,
565.2 (8) [M – C5H11]+, 551.2 (12) [M – C6H13]+. HRMS (FAB+):
calcd. for C35H48O5N2SiS 636.3053; found 636.3029.
0.135 mmol per 300 mg of SBA-15.
General Procedure for the Oxidation of the Hybrid Materials 14–16
with SbCl5: In a typical process, the hybrid material (0.10 g) was
suspended in dry dichloromethane (5 mL). The solution was stirred
at room temperature and a molar excess of SbCl5 was added. The
color of the samples immediately changed. The solids were filtered
off, extracted with dichloromethane, and dried under vacuum.
1-(10-Hexyl-10H-phenothiazin-2-yl)ethyl 3-(Triethoxysilyl)propyl-
carbamate (13): According to GP2 (without solvent) and after dry-
ing at 10–3 mbar for 1 d the carbamate 13 (1.52 g, 98%) was iso-
1
lated as a dark-yellow oil. H NMR (CD2Cl2, 300 MHz): δ = 0.59
Supporting Information (see also the footnote on the first page of
this article): Six figures; pore size distribution curves of hybrid ma-
terials, FT-IR spectra of MCM-41 and SBA-15, 13C CP-MAS
NMR spectra of 14d and solution 13C NMR spectra of 11d, Se-
lected adsorption and emission spectra of solid hybrid materials,
Q-band EPR spectra of 14c* and 14d.
(t, J = 8.8 Hz, 2 H), 0.87 (t, J = 7.0 Hz, 3 H), 1.20 (t, J = 7.0 Hz,
9 H), 1.31 (m, 4 H), 1.44 (m, 2 H), 1.47 (m, 4 H), 1.57 (m, 3 H),
1.78 (m, 2 H), 3.80 (q, J = 7.0 Hz, 6 H), 3.85 (t, J = 7.0 Hz, 2 H),
5.02 (br., 1 H), 5.68 (m, 1 H), 6.85 (m, 1 H), 6.91 (m, 3 H), 7.07
(d, J = 7.5 Hz, 1 H), 7.10 (d, J = 7.0 Hz, 1 H), 7.15 (t, J = 7.7 Hz,
1 H) ppm. 13C NMR (CD2Cl2, 75 MHz): δ = 7.9 (CH2), 14.1
(CH3), 18.5 (CH3), 22.7 (CH2), 23.0 (CH2), 23.7 (CH2), 26.9 (CH2),
27.2 (CH2), 31.9 (CH2), 43.8 (CH2), 47.7 (CH2), 58.7 (CH2), 113.7
(CH), 115.9 (CH), 120.1 (CH), 122.7 (CH), 124.4 (Cquat), 125.2
(Cquat), 127.4 (CH), 127.5 (CH), 127.6 (CH), 142.6 (Cquat), 145.7
Acknowledgments
The support of this work by the Deutsche Forschungsgemeinschaft
(DFG) (Priority Program SPP 1181 NANOMAT) and by the
Fonds der Chemischen Industrie is gratefully acknowledged. R.T.
is an Erasmus Socrates student and a recipient of a Consiliul
National al Cercetarii Stiintifice din Invatamantul Superior
(CNCSIS) grant (1315) and heartily wishes to thank Prof. I. Grosu
(Babes-Bolyai University, Cluj-Napoca) for his generous support.
(Cquat), 145.8 (Cquat), 156.0 (Cquat) ppm. IR (film): ν = 3343, 2974,
˜
2928, 2855, 1720, 1526, 1463, 1445, 1423, 1278, 1241, 1195, 1166,
1104, 1078, 957, 776, 751 cm–1. UV/Vis (CH2Cl2): λmax (ε) = 260
(28500), 312 (4400) nm. MS (FAB+): m/z (%) = 574.1 (100) [M]+,
310.1 (90). HRMS (FAB): calcd. for C30H46N2O5SSi 574.2897;
found 574.2859. C30H46N2O5SSi·0.3C10H21NO4Si (574.33 + 74.3):
calcd. C 61.07, H 8.12, N 4.96; found C 61.09, H 8.21, N 5.03.
[1] For recent reviews, see, for example: a) G. Kickelbick, Angew.
Chem. 2004, 116, 3164–3166; Angew. Chem. Int. Ed. 2004, 43,
3102–3104; b) A. Stein, Adv. Mater. 2003, 15, 763–775.
[2] a) R. Anwander, Chem. Mater. 2001, 13, 4419–4438; b) J. Mo-
rell, G. Wolter, M. Fröba, Chem. Mater. 2005, 17, 804–808; c)
C. Y. Ishii, T. Asefa, N. Coombs, M. J. MacLachlan, G. A.
Ozin, Chem. Commun. 1999, 2539–2540; d) S. Guan, S. In-
agaki, T. Ohsuna, O. Terasaki, J. Am. Chem. Soc. 2000, 122,
5660–5661; e) S. Inagaki, S. Guan, Y. Fukushima, T. Ohsuna,
O. Terasaki, J. Am. Chem. Soc. 1999, 121, 9611–9614; f) B. J.
Melde, B. T. Holland, C. F. Blanford, A. Stein, Chem. Mater.
1999, 11, 3302–3308; g) T. Asefa, M. J. MacLachlan, N. Co-
ombs, G. A. Ozin, Nature 1999, 402, 867–871; h) J. Sauer, F.
Marlow, B. Spliethoff, F. Schüth, Chem. Mater. 2002, 14, 217–
224; i) T. Abe, Y. Tachibana, M. Iwamoto, J. Chem. Soc.,
Chem. Commun. 1995, 1617–1618; j) K. R. Kloetstra, H.
van Bekkum, Stud. Surf. Sci. Catal. 1997, 105, 431–438; k)
V. R. Choudhary, S. K. Jana, B. P. Kiran, J. Catal. 2000, 192,
257–261; l) M. Iwamoto, T. Abe, Y. Tachibana, J. Mol. Catal.
A 2000, 155, 143–153; m) A. Wingen, N. Anastasievic, A.
Hollnagel, D. Werner, F. Schüth, J. Catal. 2000, 193, 248–254;
n) M. Fröba, R. Köhn, G. Bouffaud, O. Richard, G. van Tend-
eloo, Chem. Mater. 1999, 11, 2858–2865; o) A. Zecchina, D.
Scarano, G. Spoto, S. Bordiga, C. Lamberti, G. Bellussi, Stud.
Surf. Sci. Catal. 1998, 117, 343–350.
Synthesis of the MCM-41 and SBA-15 Supports: Siliceous MCM-
41 was synthesized as described in the literature.[40] A typical pro-
cedure was as follows: a 70% aqueous solution of ethylamine
(15.46 g, 240 mmol ethylamine) was added to a stirred solution of
distilled water (175 mL) and cetyltrimethylammonium bromide
(CTAB; 5.10 g, 14 mmol). Tetraethyl orthosilicate (TEOS; 20.80 g,
100 mmol) was added dropwise. The reaction mixture was stirred
for further 4 h at room temperature before being heated to 100 °C
for 1 d. The product was recovered by filtration and washed thor-
oughly with distilled water and dried at 80 °C for 12 h. The tem-
plate was eliminated by Soxhlet extraction with HCl/EtOH to ob-
tain a high content of Si–OH groups on the silica surface. SBA-15
was synthesized according to the procedure reported by Stucky and
co-workers.[41] In a typical preparation Pluronic 123 (4 g) was dis-
solved whilst stirring in 1.9  HCl (125 g) at room temperature.
The solution was heated to 40 °C before tetraethyl orthosilicate was
added. The resultant mixture was stirred for 20 h at 40 °C, followed
by aging at 100 °C for 24 h under static conditions. The solid prod-
uct was recovered by filtration and dried at 80 °C overnight. The
template was removed from the raw material by extraction with
ethanol under reflux conditions.
General Procedure for the Synthesis of the Phenothiazine-Function-
alized Hybrid Materials 14–16: Just before the grafting process, the
silica support was dehydrated carefully at 200 °C for 4 h. The aim
of this prior process was to avoid self-condensation of precursors
in the presence of surface H2O and to achieve more exposed single
silanol groups on the surface of the materials. In a typical process,
[3] a) R. Plass, S. Pelet, J. Krüger, M. Grätzel, U. Bach, J. Phys.
Chem. B 2002, 106, 7578–7580; b) X. Gao, S. Nie, J. Phys.
Chem. B 2003, 107, 11575–11578; c) F. J. Brieler, P. Grund-
mann, M. Fröba, L. Chen, P. J. Klar, W. Heimbrodt, H.-A.
Krug von Nidda, T. Kurz, A. Loidl, J. Am. Chem. Soc. 2004,
126, 797–907.
3904
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3895–3905

Carbamate-Linked (Oligo)phenothiazines in Mesoporous Silica
[4]
2007, 72, 6714–6725; e) A. W. Franz, F. Rominger, T. J. J.
Müller, J. Org. Chem. 2008, 73, 1795–1802.
[16] a) A. W. Franz, L. N. Popa, T. J. J. Müller, Tetrahedron Lett.
2008, 49, 3300–3303; b) C. S. Krämer, T. J. Zimmermann, M.
Sailer, T. J. J. Müller, Synthesis 2002, 1163–1170; c) C. S.
Krämer, K. Zeitler, T. J. J. Müller, Tetrahedron Lett. 2001, 42,
8619–8624.
a) F. J. Brieler, P. Grundmann, M. Fröba, L. Chen, P. J. Klar,
W. Heimbrodt, H.-A. Krug von Nidda, T. Kurz, A. Loidl,
Chem. Mater. 2005, 17, 795–803; b) A.-H. Lu, W.-C. Li, A.
Kiefer, W. Schmidt, E. Bill, G. Fink, F. Schüth, J. Am. Chem.
Soc. 2004, 126, 8616–8617.
a) D. E. de Vos, M. Dams, B. F. Sels, P. A. Jacobs, Chem. Rev.
2002, 102, 3615–3640; b) A. P. Wight, M. E. Davis, Chem. Rev.
2002, 102, 3589–3614; c) C. E. Song, S. Lee, Chem. Rev. 2002,
102, 3495–3524; d) A. Sayari, S. Hamoudi, Chem. Mater. 2001,
13, 3151–3168; e) M. Jia, A. Seifert, M. Berger, H. Giegengack,
S. Schulze, W. R. Thiel, Chem. Mater. 2004, 16, 877–882.
S. Angelos, E. Johansson, J. F. Stoddart, J. I. Zink, Adv. Funct.
Mater. 2007, 17, 2261–2271.
M. Sainsbury in Comprehensive Heterocyclic Chemistry (Eds.:
A. R. Katritzky, C. W. Rees), Pergamon Press, Oxford, 1984,
vol. 3, p. 995.
a) F. Mietzsch, Angew. Chem. 1954, 66, 363–371; b) M. Ione-
scu, H. Mantsch, Adv. Heterocycl. Chem. 1967, 8, 83–113; c)
C. Bodea, I. Silberg, Adv. Heterocycl. Chem. 1968, 9, 321–460;
d) L. Valzelli, S. Garattini in Principles of Psychopharmacology
(Ed.: W. G. Clark), Academic Press, New York, London, 1970,
pp. 255–258; e) C. O. Okafor, Heterocycles 1977, 7, 391–427; f)
Z. Eckstein, T. Urbanski, Adv. Heterocycl. Chem. 1978, 23, 1–
53; g) J. Szabo, J. Chem. Heterocycl. Compd. USSR (Engl.
Trans.) 1979, 15, 291–308; h) W. J. Albery, A. W. Foulds, K. J.
Hall, A. R. Hillman, R. G. Edgell, A. F. Orchard, Nature 1979,
282, 793–797.
[5]
[17] M. Sailer, A. W. Franz, T. J. J. Müller, Chem. Eur. J. 2008, 14,
2602–2614.
[18] a) M. Sailer, F. Rominger, T. J. J. Müller, J. Organomet. Chem.
2006, 691, 299–308; b) M. Sailer, R.-A. Gropeanu, T. J. J.
Müller, J. Org. Chem. 2003, 68, 7509–7512.
[19] a) A. Burger, A. C. Schmalz, J. Org. Chem. 1954, 19, 1841–
1846; b) T. Ishihara, H. Kakuta, H. Moritani, T. Ugawa, I.
Yanagisawa, Chem. Pharm. Bull. 2004, 52, 1151–1152.
[20] Wacker Chemie GmbH, DE 10 2004 028321 B3, 2005.
[21] L. Yang, J.-K. Feng, A.-M. Ren, J. Org. Chem. 2005, 70, 5987–
5996.
[22] a) W. Hammond, E. Prouzet, S. D. Mahanti, T. J. Pinnavaia,
Microporous Mesoporous Mater. 1999, 27, 19–25; b) M. H.
Lim, A. Stein, Chem. Mater. 1999, 11, 3285–3295; c) B. Marler,
U. Oberhagemann, S. Vortmann, H. Gies, Microporous Mater.
1996, 6, 375–383.
[23] S. J. Gregg, W. K. S. Sing, Adsorption, Surface Area and Poros-
ity, 2nd ed., Academic Press, London, 1982.
[6]
[7]
[8]
[24] a) M. Thommes, R. Kohn, M. Fröba, J. Phys. Chem. B 2000,
104, 7932–7943; b) M. Kruk, M. Jaroniec, A. Sayari, Langmuir
1997, 13, 6267–6273.
[25] a) K. Morishige, M. Ito, J. Chem. Phys. 2002, 117, 8036–8041;
b) P. I. Ravikovitch, A. V. Neimark, Colloid Surf. A 2001, 187,
11–21.
[9]
a) I. Forrest, F. Forrest, Biochim. Biophys. Acta 1958, 29, 441–
442; b) Y. Iida, Bull. Chem. Soc. Jpn. 1971, 44, 663–667; c) J.-
C. Moutet, G. Reverdy, Nouv. J. Chim. 1983, 7, 105–113.
[10] For the UV/Vis and EPR spectra of 10-methylphenothiazine,
see, for example: a) H. J. Shine, E. E. Mach, J. Org. Chem.
1965, 30, 2130–2139; b) H. J. Shine, D. R. Thompson, C. J.
Veneziani, Heterocycl. Chem. 1967, 4, 517–527; c) for the cy-
clovoltammetric and spectroscopic data of phenothiazine, see,
for example: L. A. Tinker, A. J. Bard, J. Am. Chem. Soc. 1979,
101, 2316–2319; d) B. Padusek, M. K. Kalinowski, Electro-
[26] M. Kruk, M. Jaroniec, Chem. Mater. 2001, 13, 3169–3183.
[27] a) X. S. Zhao, G. Q. Lu, J. Phys. Chem. B 1998, 102, 1556–
1561; b) A. Fidalgo, L. M. Ilharco, Chem. Eur. J. 2004, 10,
392–398.
[28] N. B. Colthup, An Introduction to Infrared and Raman Spec-
troscopy (Eds.: L. H. Daly, S. E. Wiberlwy), Academic Press,
Boston, 1990.
chim. Acta 1983, 28, 639–642; e) R. McIntyre, H. Gerischer, [29] P. A. Holland, H. T. Thomas, L. D. Weis, F. C. James, J. Am.
Ber. Bunsen Ges. Phys. Chem. 1984, 88, 963–969.
Chem. Soc. 1966, 88, 5075–5083.
[11] a) R. Duesing, G. Tapolsky, T. J. Meyer, J. Am. Chem. Soc.
1990, 112, 5378–5379; b) W. E. Jones, Jr., P. Chen, T. J. Meyer,
J. Am. Chem. Soc. 1992, 114, 387–388; c) A. M. Brun, A. Har-
riman, V. Heitz, J.-P. Sauvage, J. Am. Chem. Soc. 1991, 113,
8657–8663; d) H. D. Burrows, T. J. Kemp, M. J. Welburn, J.
Chem. Soc., Perkin Trans. 2 1973, 969–974; e) J.-P. Collin, S.
Guillerez, J.-P. Sauvage, J. Chem. Soc., Chem. Commun. 1989,
776–778; f) J. Daub, R. Engl, J. Kurzawa, S. E. Miller, S.
Schneider, A. Stockmann, M. R. Wasielewski, J. Phys. Chem.
A 2001, 105, 5655–5665.
[12] a) R. C. Wheland, J. L. Gillson, J. Am. Chem. Soc. 1976, 98,
3916–3925; b) P. Berges, J. Kudnig, G. Klar, E. Sanchez-Marti-
nez, R. Diaz-Calleja, Synth. Met. 1992, 46, 207–219; c) A.
Knorr, J. Daub, Angew. Chem. 1995, 107, 2925–2927; Angew.
Chem. Int. Ed. Engl. 1995, 34, 2664–2666; d) H. Spreitzer, M.
Scholz, G. Gescheidt, J. Daub, Liebigs Ann. 1996, 2069–2077;
e) H. Spreitzer, J. Daub, Chem. Eur. J. 1996, 2, 1150–1158.
[13] N. Nambu, S. Sakurai, T. Nagai, Chem. Pharm. Bull. 1974, 22,
1405–1410.
[30] B. Valeur, Molecular Fluorescence, Wiley-VCH, Weinheim,
2002.
[31] H. Oka, J. Mater. Chem. 2008, 18, 1927–1934.
[32] a) H. J. Shine in Organic Free Radicals (Ed.: W. A. Pryor),
American Chemical Society, Washington, DC, 1978; b) E.
Bosch, J. K. Kochi, J. Chem. Soc., Perkin Trans. 1 1995, 1057–
1064.
[33] T. Okamoto, M. Kuratsu, M. Kozaki, K. Hirotsu, A. Ichimura,
T. Matsushita, K. Okada, Org. Lett. 2004, 6, 3493–3496.
[34] J. K. Kochi, D. Sun, S. V. Rosokha, J. Am. Chem. Soc. 2004,
126, 1388–1401.
[35] H. G. O. Becker, R. Beckert, G. Domschke, E. Fanghänel,
W. D. Habicher, P. Metz, D. Pavel, K. Schwetlick (Eds.), Or-
ganikum, 21st ed., Wiley-VCH, Weinheim, 2001.
[36] N. P. Buu-Hoi, N. Hoan, J. Chem. Soc. 1951, 1834–1836.
[37] A. W. Franz, T. J. J. Müller, Synthesis 2008, 1121–1125.
[38] M. Hesse, H. Meier, B. Zeeh, Spektroskopische Methoden in der
organischen Chemie, Georg Thieme, Stuttgart, 1991, pp. 69.
[39] P. Zanello, in: Ferrocenes (Eds.: A. Togni, T. Hayashi), VCH,
Weinheim, 1995, p. 317.
[14] Z. Zhou, A. W. Franz, M. Hartmann, A. Seifert, T. J. J. Müller,
W. R. Thiel, Chem. Mater. 2008, 20, 4986–4992.
[15] a) T. J. J. Müller, Tetrahedron Lett. 1999, 40, 6563–6566; b)
C. S. Krämer, K. Zeitler, T. J. J. Müller, Org. Lett. 2000, 2,
3723–3726; c) C. S. Krämer, T. J. J. Müller, Eur. J. Org. Chem.
2003, 3534–3548; d) M. Hauck, J. Schönhaber, A. J. Zucchero,
K. I. Hardcastle, T. J. J. Müller, U. H. F. Bunz, J. Org. Chem.
[40] W. Y. Lin, Q. Cai, W. Q. Pang, Y. Yue, Chem. Commun. 1998,
2473–2474.
[41] D. Y. Zhao, Q. S. Huo, J. L. Feng, B. F. Chmelka, G. D. Stucky,
J. Am. Chem. Soc. 1998, 120, 6024–6036.
Received: March 27, 2009
Published Online: July 1, 2009
Eur. J. Org. Chem. 2009, 3895–3905
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3905