1,2,3-Triazole-Diketopyrrolopyrrole Derivatives with Tunable Solubility and Intermolecular Interactions

Article abstract of DOI:10.1002/ejoc.201600120

1,2,3-Triazole rings bearing hydrophobic aliphatic or hydrophilic oligoether chains were easily introduced at the two ends of the conjugated skeleton of bisthiophene-diketopyrrolopyrrole (TDPP) derivatives by simple click cycloaddition reactions. The combination of side chains with different structures and polarities on the triazole rings with the side chains on the N-atoms of the lactam groups of the TDPP moiety enabled the solubility and the solid-state spectroscopic properties of the resulting conjugated molecules to be tuned. Formation of nanostructured aggregates and dependence of their spectroscopic behavior on the substitution pattern were investigated.

Full text of DOI:10.1002/ejoc.201600120

DOI: 10.1002/ejoc.201600120
Full Paper
Dyes/Pigments
1,2,3-Triazole–Diketopyrrolopyrrole Derivatives with Tunable
Solubility and Intermolecular Interactions
Angela Punzi,[a] Eliana Maiorano,[a] Francesca Nicoletta,[b] Davide Blasi,[c,d]
Antonio Ardizzone,[c,d] Nora Ventosa,[c,d] Imma Ratera,[c,d] Jaume Veciana*[c,d] and
Gianluca Maria Farinola*[a,e]
Abstract: 1,2,3-Triazole rings bearing hydrophobic aliphatic or on the N-atoms of the lactam groups of the TDPP moiety
hydrophilic oligoether chains were easily introduced at the enabled the solubility and the solid-state spectroscopic proper-
two ends of the conjugated skeleton of bisthiophene–diketo- ties of the resulting conjugated molecules to be tuned. Forma-
pyrrolopyrrole (TDPP) derivatives by simple click cycloaddition tion of nanostructured aggregates and dependence of their
reactions. The combination of side chains with different struc- spectroscopic behavior on the substitution pattern were investi-
tures and polarities on the triazole rings with the side chains gated.
Introduction
cess to families of homologous molecules with finely tunable
optical and electronic properties.
In recent years, diketopyrrolo[3,4-c]pyrrole (DPP) structures
(already well known as high-performance organic industrial pig-
ments) have been widely explored as building blocks in the
synthesis of a variety of functional materials with diverse appli-
cations ranging from photonics and electronics to biology.
These include fluorescent probes,[4] two-photon-absorbing ma-
terials,[3h,4,5] dye lasers,[6] organic light-emitting diodes,[7] or-
ganic thin-film transistors, and organic photovoltaics.[8] The in-
troduction of substituents of various lengths and polarities,
most commonly on the N-atom of the lactam groups of the
DPP unit in the conjugated backbone, enables fine-tuning of
the solubility and molecular packing, which, in turn, impact the
photophysical properties in the solid state as well as the
charge-transport characteristics of the DPP-based com-
pounds.[9] Recently, polar triethylene glycol (TEG) chains have
been reported as good stack-inducing agents for DPP deriva-
tives:[10] a 3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-
dione (TDPP) based copolymer functionalized with TEG side
chains for high-mobility organic field-effect transistors (electron
mobilities up to 3 cm2 V –1s–1) was reported by Patil et al.,[10a]
whereas Yang et al. demonstrated that the strong self-assem-
bling effect awarded by the TEG side chains is useful to improve
the photovoltaic performance in polymeric systems (power
conversion efficiency from 6.2 to 7.0 % with TEG modifica-
tion).[10c] The introduction of hydrophilic oligoether chains also
confers processability of DPP derivatives in environmentally
friendly polar solvents and extends the use of DPP dyes in
aqueous environments for biological applications.[11] Oligoe-
ther-chain-functionalized DPP derivatives have been reported
for the detection of Zn2+ ions in living cells,[11a] two-photon
fluorescence microscopy,[11c–11e] and two-photon photody-
namic therapy.[11f]
Controlling intermolecular interactions and supramolecular ar-
rangement is one of the key goals in studies on photo- and
electroactive organic materials.[1,2] In fact, the spectroscopic
and electronic properties of molecular materials critically de-
pend on intermolecular interactions in the solid state. Control
of intermolecular interactions, supramolecular organization,
and nanostructure formation can be achieved on both a macro-
scopic level by the processing conditions (e.g., temperature, sol-
vent) and a molecular level by tailoring the molecular structure.
The latter approach can be pursued by introducing different
substituents that can determine noncovalent interactions
(e.g., π–π stacking, hydrogen bonding, electrostatic, and
van der Waals and hydrophobic interactions).[3] The availability
of simple protocols to introduce substituents enables easy ac-
[a] Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro,
Via Orabona 4, 70126 Bari, Italy
E-mail: gianlucamaria.farinola@uniba.it
http://www.chimica.uniba.it
[b] Dipartimento di Chimica, Università degli Studi di Catania,
viale A. Doria 6, 95125 Catania, Italy
[c] Institut de Ciència de Materials de Barcelona – Consejo Superior de
Investigaciones Científicas (ICMAB-CSIC),
Campus de la UAB, 08193 Bellaterra, Barcelona, Spain
E-mail: vecianaj@icmab.es
http://icmab.es
[d] CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN),
Bellaterra, 08193 Barcelona, Spain
http://www.ciber-bbn.es
[e] CNR-ICCOM Istituto di Chimica dei Composti Organometallici,
Via Orabona 4, 70126 Bari, Italy
http://www.iccom.cnr.it
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under http://dx.doi.org/10.1002/ejoc.201600120.
Eur. J. Org. Chem. 2016, 2617–2627
2617
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
In this study, we report the synthesis and investigation of compounds 4 contain solubilizing groups with different proper-
the solubility, intermolecular interactions, and formation of ties on the lactam rings of the TDPP core {i.e., hydrophobic 2-
nanostructured aggregates of thiophene-functionalized DPP ethylhexyl chains for 4a, hydrophilic 2-[2-(2-methoxethoxy)-
derivatives (i.e., TDPP) in which 1,2,3-triazole moieties are conju- ethoxy]ethyl chains for 4b, and thermocleavable Boc groups for
gated as terminal rings to the central TDPP core. The synthetic 4c}. The yield of each synthetic step is shown in Table 1.
approach proposed enables easy access to a series of TDPP
molecules that combine functionalization with side chains of
various structures and polarities [e.g., hydrophobic alkyl chains,
hydrophilic polyethylene glycol (PEG) chains, and thermocleav-
able tert-butoxycarbonyl (Boc) groups] at both the terminal tri-
azole rings and the lactam N atoms. Tuning of polarity and,
thus, the solubility and intermolecular interactions by com-
bined functionalization with alkyl and PEG chains is studied,
also covering spectroscopic investigation of J- and H-aggre-
gates. Preparation of organic nanoparticles (ONPs) and investi-
gation of their spectroscopic and morphological behavior is
also reported.
Scheme 1. Synthetic route to compounds 4a–c.
Table 1. Yields of compounds 2–4.
Results and Discussion
R
Compound
Yield [%]
1,2,3-Triazoles are aromatic heterocycles that are highly stable
to acidic and basic hydrolysis and oxidative and reductive con-
ditions. At the same time, they are capable of active participa-
tion in hydrogen bonding as well as dipole–dipole and π-stack-
ing interactions.[12] In addition, these units can be easily intro-
duced, which enables facile functionalization of the conjugated
backbone of TDPP with various substituents, including a num-
ber of hydrophilic oligoether chains. This approach allows the
obtainment of compounds with tailored solubilities in environ-
mentally friendly polar solvents, such as alcohols or water, po-
tentially useful for green organic electronics and solution proc-
essing of different layers from orthogonal solvents. Moreover,
the low cytotoxicity of these solvents makes the TEG-functional-
ized TDPP derivatives interesting for biological applications. In
continuation of our previous studies,[13] the triazole units con-
nected to the TDPP core presented in this work were synthe-
sized by copper-catalyzed 1,3-dipolar azide–alkyne cycloaddi-
tion (CuAAC),[14] which is the most prominent example of click
chemistry.[15] This reaction offers excellent regioselectivity, good
reproducibility, and a high degree of compatibility with a vari-
ety of reaction conditions and functional groups, which makes
it appropriate for a variety of applications.[16] This straightfor-
ward approach can be easily extended to the synthesis of more
complex functionalized derivatives because of the synthetic
and commercial availability of a number of variously functional-
ized organic azides.
2-ethylhexyl
2a
3a
4a
65
98
98
CH3O(CH2CH2O)2CH2CH2
2b
3b
4b
55
72
95
Boc
2c
3c
4c
88
70
98
The synthetic sequence was completed by treating com-
pounds 4a–c with organic azides in the presence of
Cu(OAc)2·H2O in H2O (Scheme 2), which enabled easy introduc-
tion of various substituents in the terminal positions of the con-
jugated backbone. The cycloaddition reactions proceeded suc-
cessfully with both alkyl azides (e.g., n-octyl azide and n-hexa-
decyl azide) and 2-{2-[2-(2-azidoethoxy)ethoxy]ethoxy}ethanol.
As reported in Table 2, good to excellent yields of the desired
triazole-functionalized TDPP derivatives 5a–f were obtained.
Scheme 2. Synthetic route to compounds 5a–f.
Our protocol for the synthesis of diketopyrrolopyrrole deriva-
tives bearing 1,2,3-triazole units conjugated with the TDDP core
We qualitatively investigated the solubilities of compounds
was based on the use of alkynes 4a–c, which were easily pre- 5a–f in solvents of different polarities. For these experiments,
pared according to Scheme 1 and as detailed in the Experimen- 1 mg of compound was mixed with 0.5 mL of solvent, and if
tal Section. Heck–Cassar–Sonogashira coupling between TDPP the compound was not soluble at room temperature, the sus-
dibrominated derivatives 2a–c, prepared from the correspond- pension was heated. The results are summarized in Table 3. All
ing precursors 1a–c by treatment with N-bromosuccinimide compounds 5a–f were found to be insoluble in hexane but
(NBS), and (trimethylsilyl)acetylene in the presence of Pd(PPh3)4, soluble in toluene with the exception of compound 5f, which
CuI, and trimethylamine led to intermediates 3a–c. Subsequent was only partly soluble upon heating. Moreover, they were
displacement of the trimethylsilyl groups by treatment with po- found to be well soluble in halogenated solvents such as di-
tassium fluoride provided alkynes 4a–c in quantitative yields; chloromethane, chloroform, and o-dichlorobenzene as well as
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2618
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Table 2. Structures of compounds 5a–f.
in tetrahydrofuran and acetone. As expected, the solubilities of the TDDP core and the 1,2,3-triazole units, was found to be
these compounds in polar protic solvents such as alcohols and soluble in water at room temperature. Remarkably, only very
water increased as the number of hydrophilic oligoether chains
increased. Compound 5f, which has oligoether chains on both
few water-soluble DPP derivatives for biological applications
have been reported.[11,17]
The UV/Vis absorption and photoluminescence emission
spectra of compounds 5a–f in chloroform solution are reported
in Figure 1. All compounds gave very similar spectra in solution,
with the exception of compound 5c. Only very small differences
in the solution absorption profiles were observed for com-
pounds 5a, 5b, and 5d–f bearing alkyl and/or oligoether chains
on the conjugated backbone. On the contrary, a blueshift of ca.
50 nm was detected for 5c, likely as a result of minor planarity
caused by the higher steric hindrance of the Boc groups on the
TDDP core. The higher planarity of compounds 5a, 5b, and 5d–
f with respect to compound 5c also caused a better resolved
vibronic structure near the wavelength of the maximum ab-
sorption (λabs). The optical band gaps (Eg) of compounds 5a–f
were estimated from the onset of absorption (λonset) of the UV/
Table 3. Solubilities of compounds 5a–f in solvents of different polarities.[a]
Solvent
5a
5b
5c
5d
5e
5f
n-Hexane
Toluene
o-Dichlorobenzene
CH2Cl2
–
+
–
–
++
++
++
++
++
+
+
++
+
–
–
++
++
++
++
++
+
+
++
+
–
++
++
++
++
++
++
++
++
++
–
++
++
++
++
++
+
++
++
++
++
–
–
+
–
–
++
++
++
++
+
++
++
++
++
CHCl3
THF
2-Propanol
Ethanol
Acetone
Methanol
H2O
+
++
–
–
–
[a] ++, soluble at room temperature; +, soluble upon heating; , partly
soluble; –, insoluble.
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2619
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Vis spectra in chloroform solution. Very similar values of Eg ran- groups on the TDDP core produced a slight lowering of both
ging from 1.98 to 2.03 eV were obtained. All compounds 5a–f the HOMO and LUMO energy levels of compound 5c.
exhibited high molar extinction coefficients (ε) ranging from
Table 5. Electrochemical data of compounds 5a–f in dichloromethane solu-
tion.
3.39 × 104 to 5.36 × 104
M
–1 cm–1. The optical data of com-
pounds 5a–f in chloroform solution are listed in Table 4.
[a]
[b]
Eox
[V]
Ered
HOMO[c]
[eV]
LUMO[d]
[eV]
[V]
5a
0.38
0.41
0.55
0.42
0.37
0.41
–1.78
–1.74
–1.52
–1.69
–1.67
–1.65
–5.48
–5.51
–5.65
–5.52
–5.47
–5.51
–3.48
–3.50
–3.62
–3.51
–3.49
–3.53
5b
5c
5d
5e
5f
[a] Eox is the average value between the peak potential and the related re-
verse one measured for the compounds in dichloromethane solution
(10–4 ) vs. ferrocene/ferrocenium (Fc/Fc+) reference. [b] Irreversible peak po-
M
tential. [c] HOMO energy levels were estimated by the empirical equation:
HOMO = –e(Eox + 5.1 V).[18] [d] LUMO energy levels were estimated as follows:
opt
LUMO = HOMO + Egopt, in which Eg is the optigal band gap.
Figure 2 shows the normalized UV/Vis absorption spectra of
compounds 5a–f as thin films spin-coated from chloroform so-
lution (10 mg mL–1, 1000 rpm 60 s–1). Whereas in solution all
the molecules showed very similar absorption profiles, in thin
films the lengths and the nature of the chains attached to the
lactam rings and to the triazole moieties affected the intermo-
lecular interactions and, thus, their spectroscopic properties. For
all samples, there was a broadening of the absorption with re-
spect to that exhibited in solution, which showed two sepa-
rated regions: one blueshifted and one redshifted. In their work
on DPP substituted with oligothiophenes, Kirkus et al.[19] attrib-
uted this broadening to Davydov splitting between H-aggre-
gates, which show blueshifting, and J-aggregates, which show
redshifting. As reported by Kirkus et al., molecules with
branched alkyl chains at the ꢀ-position, as in 5a, show very
little differences in the absorption spectrum between solution
and thin films with the exception of a redshift in the onset for
the film. Similar behavior was also observed for 5c. Thin films
obtained from 5b and 5d seemed to give H-aggregates prefer-
entially, whereas the film of 5f, the most polar TDPP derivative,
showed the largest formation of J-aggregates. The thin film of
5e showed a behavior intermediate between that of 5a and
Figure 1. Normalized UV/Vis absorption (blue line) and emission (red line)
spectra of compounds (a) 5a, (b) 5b, (c) 5c, (d) 5d, (e) 5e, and (f) 5f in
solution (CHCl3, 10–5
M).
Table 4. Optical data of compounds 5a–f in chloroform solution.
λabs
ε × 104
M
λPLem
[nm]
λonset
Eg
[a]
[a,b]
[a]
[c]
[nm]
[
–1 cm–1
]
[nm]
[eV]
5a
5b
5c
5d
5e
5f
592
586
535
586
592
587
5.36
4.19
4.16
4.14
3.39
4.43
616
610
600
610
614
611
620
618
610
616
625
625
2.00
2.01
2.03
2.01
1.98
1.98
[a] 10–5
M CHCl3 solution. [b] Wavelength of the photoluminescence emission.
[c] Optical band gap evaluated as Eg = 1240/λonset
.
The energy levels of the frontier orbitals of compounds 5a–
f were measured by cyclic voltammetry (Figure S25, Supporting
Information). The electrochemical data of compounds 5a–f in
CH2Cl2 solution are reported in Table 5. As expected, the elec-
trochemical properties of compounds 5a, 5b, and 5d–f bearing
alkyl and/or oligoether chains were very similar, which thus
showed that variations in the side chains did not cause any
noticeable differences in the electronic properties in solution.
For all of these compounds, the HOMO and LUMO levels were
approximately the same at ca. –5.5 and –3.5 eV, respectively.
Otherwise, the introduction of more electronegative Boc
Figure 2. Normalized UV/Vis absorption of compounds of compounds (a) 5a,
(b) 5b, (c) 5c, (d) 5d, (e) 5e, and (f) 5f as thin films spin-coated from chloro-
form solution (10 mg mL–1, 1000 rpm 60 s–1).
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2620
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
that of 5f, which confirmed the importance of the TEG chains cles (ONPs) and their spectroscopic behavior. There is increasing
on stacking and organization in films.
interest in the preparation of ONPs that show fluorescence in
the near-IR region, as they can be used for in vivo imaging
because of the low absorption of biological tissues in this re-
gion.[22] To the best of our knowledge, only a few studies on
nanoparticles based on DPP derivatives have been reported, for
example, for in vivo two-photon fluorescence imaging[3h] and
in vivo photoacoustic imaging.[23] Attracted by this possibility,
we prepared ONPs of 5b and 5d as representative model mol-
ecules by using the reprecipitation method. We chose both
molecules to evaluate if direct bonding of the TEG chains on
the TDPP molecules could lead to ONPs with elevated colloidal
stability and hydrophilicity without the need for the further ad-
dition of stabilizing agents, for example, surfactants, or encap-
sulation in polymeric matrixes.[3h,22,23] The normalized absorp-
tion spectra of the two suspensions are reported in Figure 4.
Soon after their preparation, the ONPs obtained from both 5b
(i.e., 5b-NPs) and 5d (i.e., 5d-NPs) showed absorption spectra
very similar to those of their corresponding thin films. By moni-
Recently, the tert-butoxycarbonyl radical has been largely
used as protecting group of lactam functionalities in the “latent
pigment” approach,[20] as it is able to improve the solubility
and can be easily removed by thermal treatment. Moreover,
removal of thermocleavable solubilizing groups on the lactam
rings of the TDPP core was reported to be successfully em-
ployed in the fabrication of organic semiconductor films with
improved morphological stability.[21] For example, DPP-based
materials with free NH groups capable of forming a hydrogen-
bonded network were generated by thermal cleavage of tert-
butoxycarbonyl[21a,21b] and 2-octyldodecanoyl[21c] groups.
Therefore, we considered that it would be interesting to study
the thermally tunable behavior of compound 5c containing
tert-butoxycarbonyl groups on the lactam units. The IR spectra
provided evidence for the regeneration of free NH groups and
the formation of hydrogen bonds (C=O···H–N) after thermal
treatment of compound 5c at 200 °C for 5 min (Figure S26,
Supporting Information). The complete disappearance of the
C=O carbamate stretching vibration band at 1756 cm–1 and the
shift to lower energy of the C=O amide stretching vibration
band (from 1695 to 1648 cm–1), which are suggestive of
hydrogen bonding, were observed in the IR spectrum of depro-
tected 5c. Owing to elimination of the Boc groups and the for-
mation of stronger intermolecular interactions, 5c became in-
soluble in chloroform upon thermal treatment. Figure 3 shows
the normalized UV/Vis absorption spectra of thin films of com-
pound 5c before and after thermal cleavage. The thin film for
this measurement was prepared by spin coating of a chloroform
solution (10 mg mL–1, 1000 rpm 60 s–1). Thermal treatment of
the film was performed on a hot plate at 200 °C for 5 min in
air. After thermal treatment, the sample showed a lower energy
onset and a better structured absorption spectrum: a blue-
shifted peak, which was previously reported for thin films of NH
forms of TDPP-based materials[21b,21c] and indicative of more
ordered H-aggregates, and a new shoulder redshifted peak re-
lated to the J-form.
Figure 3. Normalized UV/Vis absorption of compound 5c as pristine film (blue
line) and after thermal treatment at 200 °C for 5 min (orange line).
To complete our investigation on controlled aggregation in-
duced by functionalization with groups of different polarities,
we performed a study on the formation of organic nanoparti-
Figure 4. Normalized absorption spectra over the course of 3 weeks of 5b-
NPs (top) and 5d-NPs (bottom). Arrows show the evolution trend of absorp-
tion with time.
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2621
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
toring the absorption spectra of the two suspensions over and can be explained by energy transfer between the two poly-
3 weeks (Figure 4) it was possible to observe that 5b-NPs morphs constituting the ONPs.[19] The possibility to control the
showed rearrangement of their structure towards the formation preferential formation of J-aggregates could be an important
of J-aggregates. Thus, whereas after their preparation the maxi- effort in the preparation of ONPs for in vivo imaging. The J-
mum absorption was at 528 nm (peak associated to H-aggre- aggregates can also lead to an intense nonlinear optical re-
gates), after 3 weeks the maximum appeared at 607 nm to- sponse, as for several classes of materials it is possible to ob-
gether with another peak at 645 nm, the intensity of which serve a significant increase in the two-photon absorption cross-
had increased by 36 % (peaks associated to J-aggregates). It is section of J-aggregates as compared with the monomeric spe-
interesting to observe that after 21 days the absorption spec- cies.[24]
trum of 5b-NPs is closer to that of the thin film of 5e. However,
after this time no sensitive changes occurred. The structural
reorganization in the case of 5d-NPs is much slower and less
intense, which indicates that, in this case, the long alkyl chains
govern the self-assembly process.
Transmission electron microscopy (TEM) images were ac-
quired for the two systems 1, 4, and 7 days after their prepara-
tion (Figure 5). One day after their preparation, both 5b-NPs
and 5d-NPs presented a lamellar rodlike shape with one dimen-
sion of about 40 nm and the other from 100 nm up to 1.5 μm.
The 5d-NPs sample showed a higher tendency to aggregation
than 5b-NPs and the shapes were more irregular and the rods
shorter than those found for 5b-NPs. After 4 days, we observed
elongation of 5b-NPs, which adopted a nanowire morphology,
whereas 5d-NPs maintained the initial aspect ratio. One week
after their preparation, no significant changes, either in size or
shape, were observed.
Figure 6. Normalized absorption, emission, and excitation spectra of 5b-NPs
(top) and 5d-NPs (bottom) 3 weeks after their preparation.
Summary and Conclusions
Figure 5. TEM images of 5b-NPs (left) and 5d-NPs (right) 1, 4, and 7 days
We described the synthesis of new TDPP-based compounds in
which 1,2,3-triazole rings were conjugated with the central
after their preparation.
The presence of H- and J-aggregates in these ONPs was con- TDPP core. Our synthetic sequence involved cross-coupling and
firmed by fluorescence spectroscopy (Figure 6). Thus, both 5b- cycloaddition reactions for the introduction of various hydro-
NPs and 5d-NPs showed a weak redshifted emission with re- philic chains on the conjugated skeleton, which led to com-
spect to the 5b and 5d emission in CHCl3 solution in the near- pounds with tunable solubilities in a wide range of solvents.
IR region (emission maxima for 5b-NPs and 5d-NPs appear at Remarkably, compound 5f bearing oligoether chains on both
720 and 710 nm, respectively), and their excitation spectra were the TDDP core and the 1,2,3-triazole units exhibited good water
not close to the absorption ones. In particular, the maxima in solubility, which may open the way to biological applications.
the excitation spectra peaked at the most redshifted absorption The optical and electrochemical properties of all compounds
band associated to J-aggregates. This observation is in agree- 5a–f were investigated. End capping with PEG chains (as in mol-
ment with theory, which predicts fluorescence emission of J- ecules 5e and 5f) resulted in structural modifications that were
aggregates. The coexistence of H- and J-bands in the excitation useful to obtain films in which the self-assembly process led to
spectra is typical of systems in which Davydov splitting occurs the formation of J-aggregates. These kinds of aggregates
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2622
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
in chloroform solution. Cyclic voltammetry measurements were per-
formed with an Autolab potentiostat (model PGSTAT128N) by Met-
rohm by using a conventional three-electrode configuration con-
sisting of a platinum working electrode, a platinum counter elec-
trode, and an Ag/AgCl reference electrode. All cyclic voltammetry
measurements were recorded at room temperature under nitrogen
in anhydrous dichloromethane solution (scan rate 0.1 or 0.2 V s–1).
showed a low energy gap with an absorption maximum in the
deep-red region and emission in the near-IR region and thus
may be proficiently used in the fabrication of organic photovol-
taic cells or ONPs for bioimaging applications. Molecules 5b
and 5d, end-capped with alkyl chains, showed very similar ab-
sorption spectra, also in the solid state, with preferential forma-
tion of H-aggregates. The self-assembly of these two systems
was studied in detail in the preparation of 5b-NPs and 5d-NPs
by the reprecipitation method. The 5b-NPs sample showed an
The solutions were prepared as follows: a 0.1
M solution of
nBu4NPF6 solution in anhydrous dichloromethane as supporting
electrolyte was prepared in a glovebox; the proper amount of com-
intense structural reorganization process, monitored by UV/Vis pound 5 was then dissolved in the desired volume of nBu4NPF6
solution at a final concentration of 9.4 × 10–4
M
for 5a, 7.4 × 10–4
M
absorption spectroscopy and TEM, which indicated the forma-
tion of J-aggregates. This process was negligible in the case of
5d, which confirmed the key role of alkyl chains in the forma-
tion and stabilization of H-aggregates. In the case of ONPs, the
presence of the two polymorphs was confirmed by fluores-
cence spectroscopy.
for 5b, 7.5 × 10–4
M
for 5c, 4.4 × 10–4
M
for 5d, 5.6 × 10–4
M
for 5e,
and 5.3 × 10–4 for 5f and placed inside the three-electrode cell. All
measurements were calibrated by using the Fc/Fc+ redox couple as
an external standard. The HOMO and LUMO energy levels were
estimated by using the following empirical equation: EHOMO
=
–e(Eox + 5.1 V), in which Eox is the average value between the first
peak potential and the related reverse one measured for the com-
pounds in solution vs. Fc/Fc+ reference and –5.1 eV is the position
of the formal potential of the Fc/Fc+ redox couple on the Fermi
Experimental Section
scale[19] and ELUMO = EHOMO + Eg
.
opt
General Remarks: Heck–Cassar Sonogashira cross-coupling reac-
tions were performed under itrogen in oven-dried glassware in tri-
ethylamine (puriss. p.a. ≥ 99.5 %, Sigma–Aldrich). Reaction solvents
were distilled immediately prior to use as follows: chloroform was
dried by distillation from P2O5, and THF was dried by distillation
from sodium/benzophenone. Reagents were purchased at the
highest commercial quality and were used without further purifica-
tion. 2,5-Bis(2-ethylhexyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-
1,4(2H,5H)-dione (1a) was prepared according to a literature proce-
Preparation and Characterization of ONPs: A 0.4 mM solution of
5b in acetone (Tecknocroma Romil-Sps Super Purity Solvent) was
filtered by using a Teflon filter of 220 nm. The filtered solution
(250 μL) was added dropwise to MilliQ water (9.75 mL) at room
temperature under vigorous stirring. A blue-violet suspension (5b-
NPs) was obtained. The same procedure was used for the prepara-
tion of nanoparticles with 5d (5d-NPs). Suspensions were stored at
a temperature of 4 °C, and without any other further dilutions were
analyzed by UV/Vis absorption spectroscopy: spectra were meas-
ured by using a Cary UV Varian 5000 spectrometer. Fluorescence
spectra were measured by using a Cary Eclipse fluorometer exciting
samples at the maximum absorption after 21 d (605 nm for 5b-NPs
and 520 nm for 5d-NPs). TEM images were acquired with the aid of
negative staining: one drop of the sample was applied to glow-
discharged carbon-coated copper grids (SPI) for 5 min; subse-
quently, one drop of 2 % uranyl acetate was placed on the grid for
1–2 min before it was drained off. The grid was then placed in a
transmission electron microscope (Jeol JEM 1400) operating at an
acceleration voltage of 120 kV. Images were acquired by using an
Orius SC200 (Gatan) and were saved as 16-bit images.
dure.[25]
2,5-Bis{2-[2-(2-methoxyethoxy)ethoxy]ethyl}-3,6-di(thio-
phen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (1b) and di-tert-
butyl 3,6-bis(5-bromothiophen-2-yl)-1,4-dioxopyrrolo[3,4-c]pyrrole-
2,5(1H,4H)-dicarboxylate (1c) were purchased from SunaTech, Inc.,
and Tractus Company, Limited, respectively. 2-{2-[2-(2-Azido-
ethoxy)ethoxy]ethoxy}ethanol was purchased from Sigma–Aldrich
or MCAT GmbH. Preparative column chromatography was per-
formed by using Macherey–Nagel silica gel (60, particle size 0.063–
0.2 mm). Macherey–Nagel aluminum sheets with silica gel 60 F254
were used for TLC analyses. All new compounds were characterized
by 1H NMR, 13C NMR, and IR spectroscopy and LCMS analysis. 1H
NMR and 13C NMR spectra were recorded with a Varian Inova at
400 and at 100.6 MHz, respectively, by using the residual proton
peak of CHCl3 at δ = 7.24 ppm as an internal standard for 1H spectra
and the signals of CDCl3 at δ = 77 ppm as an internal standard
for 13C spectra. IR spectra were recorded with a Perkin–Elmer FTIR
Spectrum Bx. High-resolution mass spectra were acquired with a
Shimadzu high-performance liquid chromatography ion trap time
of flight (LC-IT-TOF) mass spectrometer by direct infusion of the
samples by using methanol as the elution solvent. Melting points
were determined with a Reichert Microscope or a Stuart Scientific
melting point apparatus SMP3. UV/Vis absorption measurements
were performed with a Shimadzu UV-2401PC spectrophotometer.
Fluorescence emission spectra were obtained by using a Varian Cary
Eclipse fluorescence spectrophotometer. Compounds 5a–f were dis-
solved in spectrophotometric-grade chloroform at a final concentra-
3,6-Bis(5-bromothiophen-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo-
[3,4-c]pyrrole-1,4(2H,5H)-dione (2a): Synthesized according to a
modified literature procedure.[25] A nitrogen-purged, three-necked,
round-bottomed flask covered with aluminum foil and equipped
with a magnetic stirrer was charged under nitrogen with a solution
of compound 1a (0.680 g, 1.30 mmol) in dry chloroform (30 mL).
N-Bromosuccinimide (0.485 g, 2.72 mmol) was added in one por-
tion, and then the mixture was stirred at room temperature in the
dark for 24 h. The mixture was poured into methanol (80 mL), and
the resulting suspension was stirred at room temperature for 5 min.
The solid was then collected by vacuum filtration and washed with
several portions of methanol. After drying in vacuo, pure product
2a was obtained as a dark purple solid (0.579 g, 65 %). 1H NMR
(400 MHz, CDCl3): δ = 8.61 (d, J = 4.0 Hz, 2 H), 7.20 (d, J = 4.0 Hz,
2 H), 3.97–3.83 (m, 4 H), 1.86–1.74 (m, 2 H), 1.38–1.14 (m, 16 H),
0.90–0.80 (m, 12 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ = 161.3,
tion of 1.7 × 10–5
M
for 5a, 1.5 × 10–5
M
for 5b, 1.7 × 10–5
M
for 5c,
1.4 × 10–5 for 5d, 1.9 × 10–5
M
M
for 5e, and 1.5 × 10–5 for 5f for
solution measurements. Solid-state UV/Vis spectra were acquired by 139.4, 135.4, 131.4, 131.1, 119.0, 107.9, 46.0, 39.1, 30.1, 28.3, 23.5,
depositing compounds 5a–f onto 1 cm × 1 cm quartz glasses by
23.0, 14.0, 10.4 (one coincident signal not observed) ppm. IR (KBr):
spin coating (1000 rpm 60 s–1) from a chloroform solution of con-
ν = 3085, 2957, 2926, 2859, 1655, 1556, 1449, 1412, 1399, 1100 cm–1
.
˜
centration 10 mg mL–1. Optical energy band gaps (Eg) were esti- HRMS (LC-IT-TOF): calcd. for C30H38Br2N2O2S2 [M + Na]+ 703.0634;
mated from absorption onset wavelengths (Eg = 1240/λonset [eV])
found 703.0634.
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2623
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
3,6-Bis(5-bromothiophen-2-yl)-2,5-bis{2-[2-(2-methoxyethoxy)-
ethoxy]ethyl}pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (2b): Syn-
thesized according to a modified literature procedure.[10] A round-
bottomed flask covered with aluminum foil and equipped with a
magnetic stirrer was charged with a solution of compound 1b
(1.000 g, 1.69 mmol) in dry chloroform (30 mL). After cooling to
0 °C, N-bromosuccinimide (0.602 g, 3.38 mmol) was added in one
portion. The mixture was stirred at 0 °C in the dark for 1 h, then
quenched with a saturated aqueous solution of NH4Cl (30 mL), and
extracted with dichloromethane (3 × 60 mL). The combined organic
extracts were washed with an aqueous solution of NaCl (3 × 30 mL),
dried with Na2SO4, and concentrated under vacuum. The crude
product was purified by washing with several aliquots of methanol.
After drying in vacuo, pure product 2b was obtained as a dark
δ = 161.5, 139.6, 135.2, 133.5, 130.5, 128.4, 108.9, 104.2, 96.7, 46.1,
39.1, 30.2, 28.4, 23.6, 23.0, 14.0, 10.5, –0.30 (one coincident signal
not observed) ppm. IR (KBr): ν = 2955, 2927, 2863, 2139, 1665, 1554,
˜
853 cm–1. HRMS (LC-IT-TOF): calcd. for C40H56N2O2S2Si2 [M + Na]+
739.3214; found 739.3234.
2,5-Bis{2-[2-(2-methoxyethoxy)ethoxy]ethyl}-3,6-bis{5-[(tri-
methylsilyl)ethynyl]thiophen-2-yl}pyrrolo[3,4-c]pyrrole-
1,4(2H,5H)-dione (3b): A nitrogen-purged, three-necked, round-
bottomed flask equipped with a magnetic stirrer and a condenser
was charged under nitrogen with compound 2b (0.533 g,
0.71 mmol), Pd(PPh3)4 (46 mg, 0.04 mmol), and CuI (15 mg,
0.08 mmol). Triethylamine (15 mL) and (trimethylsilyl)acetylene
(0.4 mL, 2.89 mmol) were quickly added. The mixture was heated
at 40 °C for 2 h, and the progress of the reaction was monitored by
TLC. The mixture was cooled to room temperature, then quenched
with a saturated aqueous solution of NH4Cl (30 mL), and extracted
with dichloromethane (3 × 60 mL). The combined organic extracts
were washed with an aqueous solution of NaCl (3 × 30 mL), dried
with Na2SO4, and concentrated under vacuum. The crude product
was purified by column chromatography on silica gel (CH2Cl2/acet-
one, 9:1; Rf = 0.68). A dark purple solid was isolated (0.401 g, 72 %).
M.p. 112–114 °C (hexane). 1H NMR (400 MHz, CDCl3): δ = 8.65 (d,
J = 4.0 Hz, 2 H), 7.26 (d, J = 4.0 Hz, 2 H), 4.19 (t, J = 6.0 Hz, 4 H),
3.73 (t, J = 6.0 Hz, 4 H), 3.62–3.57 (m, 4 H), 3.56–3.50 (m, 8 H), 3.46–
3.42 (m, 4 H), 3.30 (s, 6 H), 0.24 (s, 18 H) ppm. 13C NMR (100.6 MHz,
CDCl3): δ = 161.2, 139.5, 134.7, 133.3, 130.3, 128.5, 108.7, 104.2, 96.6,
71.8, 70.7, 70.5, 70.5, 68.9, 58.9, 42.0, –0.4 (one coincident signal not
1
purple solid (0.697g, 55 %). H NMR (400 MHz, CDCl3): δ = 8.44 (d,
J = 4.0 Hz, 2 H), 7.14 (d, J = 4.0 Hz, 2 H), 4.11 (t, J = 5.8 Hz, 4 H),
3.71 (t, J = 5.8 Hz, 4 H), 3.61–3.56 (m, 4 H), 3.55–3.49 (m, 8 H), 3.46–
3.41 (m, 4 H), 3.29 (s, 6 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ =
161.1, 139.3, 134.8, 131.2, 131.0, 119.2, 107.8, 71.8, 70.7, 70.5, 70.4,
68.8, 58.9, 42.1 (one coincident signal not observed) ppm. IR (KBr):
ν = 3087, 2898, 2870, 1652, 1555, 1396, 1129, 1119 cm–1. HRMS
˜
(LC-IT-TOF): calcd. for C28H34Br2N2O8S2 [M + Na]+ 771.0016; found
770.9985.
Di-tert-butyl 3,6-Bis(5-bromothiophen-2-yl)-1,4-dioxopyrr-
olo[3,4-c]pyrrole-2,5(1H,4H)-dicarboxylate (2c): Synthesized ac-
cording to a modified literature procedure.[26] A round-bottomed
flask covered with aluminum foil and equipped with a magnetic
stirrer was charged with a solution of compound 1c (0.500 g,
1.00 mmol) in dry chloroform (30 mL). N-Bromosuccinimide
(0.391 g, 2.20 mmol) was then added in one portion at room tem-
perature, and the mixture was stirred at the same temperature in
the dark for 72 h. The mixture was poured into methanol (100 mL),
and the resulting suspension was stirred at room temperature for
5 min. The solid was then collected by vacuum filtration and
washed with several portions of hot methanol. After drying in
vacuo, pure product 2c was obtained as a purple solid (0.580 g,
observed) ppm. IR (KBr): ν = 2869, 2804, 2136, 1660, 1555, 1442,
˜
1398, 1138, 1093, 1055, 845 cm–1. HRMS (LC-IT-TOF): calcd. for
C38H52N2O8S2Si2 [M + Na]+ 807.2596; found 807.2612.
Di-tert-butyl 1,4-Dioxo-3,6-bis{5-[(trimethylsilyl)ethynyl]thio-
phen-2-yl}pyrrolo[3,4-c]pyrrole-2,5(1H,4H)-dicarboxylate (3c): A
nitrogen-purged, three-necked, round-bottomed flask equipped
with a magnetic stirrer and a condenser was charged under nitro-
gen with compound 2c (0.247 g, 0.38 mmol), Pd(PPh3)4 (23 mg,
0.02 mmol), CuI (8 mg, 0.04 mmol), and anhydrous THF (25 mL).
Triethylamine (0.1 mL) and (trimethylsilyl)acetylene (0.21 mL,
1.52 mmol) were quickly added. The mixture was heated at 40 °C
for 3 h, and the progress of the reaction was monitored by TLC. The
mixture was cooled to room temperature, then quenched with a
saturated aqueous solution of NH4Cl (30 mL), and extracted with
dichloromethane (3 × 60 mL). The combined organic extracts were
washed with an aqueous solution of NaCl (3 × 30 mL), dried with
Na2SO4, and concentrated under vacuum. The crude product was
purified by column chromatography on silica gel (CH2Cl2/hexane,
8:2; Rf = 0.66). A dark purple solid was isolated (0.182 g, 70 %).
Darkening of the product was observed upon heating (m.p.
1
88 %). H NMR (400 MHz, CDCl3): δ = 8.04 (d, J = 4.0 Hz, 2 H), 7.12
(d, J = 4.0 Hz, 2 H), 1.59 (s, 18 H) ppm. 13C NMR (100.6 MHz, CDCl3):
δ = 158.6, 148.8, 136.7, 134.5, 131.0, 130.9, 120.9, 110.3, 86.3, 27.7
(one coincident signal not observed) ppm. IR (KBr): ν = 2978, 2924,
˜
1748, 1689, 1570, 1410, 1381, 1303, 1218, 1149, 1104 cm–1. HRMS
(LC-IT-TOF): calcd. for C24H22Br2N2O6S2 [M + Na]+ 678.9178; found
678.9196.
2,5-Bis(2-ethylhexyl)-3,6-bis{5-[(trimethylsilyl)ethynyl]thio-
phen-2-yl}pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (3a): Synthe-
sized according to a modified literature procedure.[27] A nitrogen-
purged, three-necked, round-bottomed flask equipped with a mag-
netic stirrer and a condenser was charged under nitrogen with com-
pound 2a (0.500 g, 0.73 mmol), Pd(PPh3)4 (46 mg, 0.04 mmol), and
CuI (15 mg, 0.08 mmol). Triethylamine (12 mL) and (trimethyl-
silyl)acetylene (0.5 mL, 3.75 mmol) were quickly added. The mixture
was heated at 40 °C for 1 h, and the progress of the reaction was
monitored by TLC. The mixture was cooled to room temperature,
then quenched with a saturated aqueous solution of NH4Cl (30 mL),
and extracted with dichloromethane (3 × 60 mL). The combined
organic extracts were washed with an aqueous solution of NaCl
(3 × 30 mL), dried with Na2SO4, and concentrated under vacuum.
The crude product was purified by washing with several aliquots of
methanol, which led to pure 3a as a dark purple solid (0.515 g,
1
> 300 °C). H NMR (400 MHz, CDCl3): δ = 8.11 (d, J = 4.0 Hz, 2 H),
7.21 (d, J = 4.0 Hz, 2 H), 1.59 (s, 18 H), 0.24 (s, 18 H) ppm. 13C NMR
(100.6 MHz, CDCl3): δ = 158.8, 148.7, 136.8, 133.8, 133.0, 130.1,
129.8, 111.0, 104.7, 96.6, 86.2, 27.7, –0.3 (one coincident signal not
observed) ppm. IR (KBr): ν = 2958, 2937, 2143, 1754, 1693, 1582,
˜
1561, 1439, 1283, 1148, 1106, 843 cm–1. HRMS (LC-IT-TOF): calcd. for
C34H40N2O6S2Si2 [M + Na]+ 715.1759; found 715.1771.
2,5-Bis(2-ethylhexyl)-3,6-bis(5-ethynylthiophen-2-yl)pyrrolo-
[3,4-c]pyrrole-1,4(2H,5H)-dione (4a): KF (0.361gr, 6.21 mmol) was
added at room temperature to a stirred suspension of compound
3a (0.445 g, 0.62 mmol) in nitrogen-purged THF (14 mL) and nitro-
98 %). M.p. 202–205 °C (dichloromethane/methanol). 1H NMR gen-purged H2O (4 mL). The mixture was stirred at room tempera-
(400 MHz, CDCl3): δ = 8.79 (d, J = 4.0 Hz, 2 H), 7.30 (d, J = 4.0 Hz,
2 H), 4.02–3.89 (m, 4 H), 1.88–1.78 (m, 2 H), 1.39–1.16 (m, 16 H),
0.90–0.82 (m, 12 H), 0.26 (s, 18 H) ppm. 13C NMR (100.6 MHz, CDCl3):
ture. Upon completion of the reaction (3 h), the mixture was
quenched with a saturated aqueous solution of NH4Cl (30 mL) and
then extracted with dichloromethane (3 × 60 mL). The combined
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2624
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
organic extracts were washed with an aqueous solution of NaCl
(3 × 30 mL), dried with Na2SO4, and concentrated under vacuum.
The crude product was purified by washing with hexane, which led
to pure compound 4a as a dark purple solid (0.348 g, 98 %). Darken-
ing of the product was observed upon heating (m.p. > 300 °C). H
NMR (400 MHz, CDCl3): δ = 8.80 (d, J = 4.0 Hz, 2 H), 7.35 (d, J =
NH4Cl (20 mL), and extracted with dichloromethane (3 × 40 mL).
The combined organic extracts were washed with an aqueous solu-
tion of NaCl (3 × 30 mL), dried with Na2SO4, and concentrated un-
der vacuum. The crude product was purified by column chromatog-
raphy on silica gel (CH2Cl2/ethyl acetate, 9.5:0.5; Rf = 0.41). A dark
purple solid was isolated (75 mg, 67 %), which was then crystallized
1
4.0 Hz, 2 H), 4.02–3.88 (m, 4 H), 3.57 (s, 2 H), 1.89–1.77 (m, 2 H), from dichloromethane/hexane [m.p. 209–210 °C (dichloromethane/
1.39–1.15 (m, 16 H), 0.90–0.81 (m, 12 H) ppm. 13C NMR (100.6 MHz,
CDCl3): δ = 161.4, 139.6, 135.2, 134.0, 130.7, 127.0, 108.9, 85.5, 76.3,
46.0, 39.1, 30.1, 28.3, 23.5, 23.0, 14.0, 10.4 (one coincident signal not
hexane)]. 1H NMR (400 MHz, CDCl3): δ = 8.92 (d, J = 4.0 Hz, 2 H),
7.79 (s, 2 H), 7.44 (d, J = 4.0 Hz, 2 H), 4.38 (t, J = 7.2 Hz, 4 H), 4.09–
3.98 (m, 4 H), 1.98–1.87 (m, 6 H), 1.42–1.15 (m, 36 H), 0.78–0.90 (m,
18 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ = 161.6, 141.8, 139.9,
138.4, 136.3, 128.9, 125.0, 119.9, 108.3, 50.6, 46.0, 39.1, 31.7, 30.2,
30.1, 29.0, 28.9, 28.3, 26.4, 23.6, 23.0, 22.6, 14.0, 14.0, 10.5 (one coin-
observed) ppm. IR (KBr): ν = 3259, 2958, 2928, 2856, 1660, 1559,
˜
1452, 1403, 1095, 827 cm–1. HRMS (LC-IT-TOF): calcd. for
C
34H40N2O2S2 [M + Na]+ 595.2423; found 595.2430.
cident signal not observed) ppm. IR (KBr): ν = 3117, 2958, 2923,
˜
3,6-Bis(5-ethynylthiophen-2-yl)-2,5-bis{2-[2-(2-methoxyeth-
oxy)ethoxy]ethyl}pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (4b):
KF (0.281gr, 4.84 mmol) was added at room temperature to a stirred
suspension of compound 3b (0.380 g, 0.484 mmol) in nitrogen-
purged THF (14 mL) and nitrogen-purged H2O (4 mL). The mixture
was stirred at room temperature. Upon completion (3 h) of the
reaction, the mixture was quenched with a saturated aqueous solu-
tion of NH4Cl (30 mL) and then extracted with dichloromethane
(3 × 60 mL). The combined organic extracts were washed with an
aqueous solution of NaCl (3 × 30 mL), dried with Na2SO4, and con-
centrated under vacuum, which led to pure 4b as a dark purple
solid (0.295 g, 95 %). Darkening of the product was observed upon
2954, 1647, 1553, 1430, 1241, 1077, 1058, 817 cm–1. HRMS (LC-IT-
TOF): calcd. for C50H74N8O2S2 [M + Na]+ 905.5268; found 905.5260.
2,5-Bis{2-[2-(2-methoxyethoxy)ethoxy]ethyl}-3,6-bis[5-(1-octyl-
1H-1,2,3-triazol-4-yl)thiophen-2-yl]pyrrolo[3,4-c]pyrrole-
1,4(2H,5H)-dione (5b): Compound 4b (100 mg, 0.156 mmol) and
n-octyl azide (73 mg, 0.47 mmol) were added at room temperature
to a solution of Cu(OAc)2·H2O (6 mg, 0.03 mmol) in H2O (14 mL) in
a round-bottomed flask equipped with a magnetic stirrer and a
condenser. The mixture was heated at 80 °C and vigorously stirred.
Upon completion of the reaction (16 h, TLC analysis), the mixture
was cooled to room temperature, then quenched with a saturated
aqueous solution of NH4Cl (30 mL), and extracted with dichloro-
methane (3 × 50 mL). The combined organic extracts wasere
washed with an aqueous solution of NaCl (3 × 30 mL), dried with
Na2SO4, and concentrated under vacuum. The crude product was
purified by column chromatography on silica gel (CH2Cl2/acetone,
7:3; Rf = 0.72). A dark purple solid was isolated (129 mg, 87 %),
which was then crystallized from dichloromethane/hexane [m.p.
1
heating (m.p. > 300 °C). H NMR (400 MHz, CDCl3): δ = 8.65 (d, J =
4.0 Hz, 2 H), 7.32 (d, J = 4.0 Hz, 2 H), 4.20 (t, J = 6.0 Hz, 4 H), 3.74
(t, J = 6.0 Hz, 4 H), 3.63–3.58 (m, 4 H), 3.57–3.50 (m, 10 H), 3.47–
3.43 (m, 4 H), 3.31 (s, 6 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ =
161.2, 139.6, 134.6, 133.9, 130.6, 127.2, 108.8, 85.5, 76.2, 71.8, 70.7,
70.5, 70.5, 68.9, 58.9, 42.1 (one coincident signal not observed) ppm.
IR (KBr): ν = 3239, 2910, 2871, 1655, 1553, 1404, 1134, 1119 cm–1
.
˜
1
HRMS (LC-IT-TOF): calcd. for C32H36N2O8S2 [M + Na]+ 633.1805;
found 633.1810.
148–150 °C (dichloromethane/hexane)]. H NMR (400 MHz, CDCl3):
δ = 8.82 (d, J = 4.0 Hz, 2 H), 7.79 (s, 2 H), 7.45 (d, J = 4.0 Hz, 2 H),
4.36 (t, J = 7.2 Hz, 4 H), 4.29 (t, J = 6.0 Hz, 4 H), 3.78 (t, J = 6.2 Hz,
4 H), 3.64–3.60 (m, 4 H), 3.58–3.51 (m, 8 H), 3.45–3.40 (m, 4 H), 3.28
(s, 6 H), 1.98–1.85 (m, 4 H), 1.38–1.18 (m, 20 H), 0.84 (t, J = 7.0 Hz,
6 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ = 161.3, 141.6, 139.7,
138.5, 135.9, 128.7, 125.0, 120.0, 108.1, 71.8, 70.7, 70.5, 69.0, 58.9,
50.6, 41.9, 31.6, 30.2, 29.0, 28.9, 26.4, 22.5, 14.0 (two coincident sig-
Di-tert-butyl 3,6-Bis(5-ethynylthiophen-2-yl)-1,4-dioxopyrrolo-
[3,4-c]pyrrole-2,5(1H,4H)-dicarboxylate (4c): KF (71 mg,
1.21 mmol) was added at room temperature to a stirred suspension
of compound 3c (84 mg, 0.12 mmol) in nitrogen-purged THF (8 mL)
and nitrogen-purged H2O (2 mL). The mixture was stirred at room
temperature. Upon completion of the reaction (1.5 h), the mixture
was quenched with a saturated aqueous solution of NH4Cl (30 mL)
and extracted with dichloromethane (3 × 50 mL). The combined
organic extracts were washed with an aqueous solution of NaCl
(3 × 30 mL), dried with Na2SO4, and concentrated under vacuum,
which led to pure 4c as a dark purple solid (0.065 g, 98 %). Darken-
nals not observed) ppm. IR (KBr): ν = 3119, 2923, 2854, 1656, 1553,
˜
1431, 1242, 1108, 1067 cm–1. HRMS (LC-IT-TOF): calcd. for
C48H70N8O8S2 [M + Na]+ 973.4650; found 973.4619.
Di-tert-butyl 3,6-Bis[5-(1-hexyl-1H-1,2,3-triazol-4-yl)thiophen-2-
yl]-1,4-dioxopyrrolo[3,4-c]pyrrole-2,5(1H,4H)-dicarboxylate
(5c): Compound 4c (65 mg, 0.12 mmol) and n-octyl azide (55 mg,
0.36 mmol) were added at room temperature to a solution of
Cu(OAc)2·H2O (6 mg, 0.03 mmol) in H2O (5 mL) in a round-bottomed
flask equipped with a magnetic stirrer and a condenser. The mixture
was heated at 100 °C and vigorously stirred. After 24 h, n-octyl
azide (55 mg, 0.36 mmol) and Cu(OAc)2·H2O (6 mg, 0.03 mmol)
were added, and then the mixture was heated at 100 °C for another
24 h. The progress of the reaction was monitored by TLC. The mix-
ture was cooled to room temperature, then quenched with a satu-
1
ing of the product was observed upon heating (m.p. > 300 °C). H
NMR (400 MHz, CDCl3): δ = 8.16 (d, J = 4.0 Hz, 2 H), 7.28 (d, J =
4.0 Hz, 2 H), 3.56 (s, 2 H), 1.59 (s, 18 H) ppm. 13C NMR (100.6 MHz,
CDCl3): δ = 158.7, 148.6, 136.9, 133.9, 133.5, 130.5, 128.4, 111.2, 86.3,
85.8, 76.2, 27.7 (one coincident signal not observed) ppm. IR (KBr):
ν = 3271, 2969, 2921, 1757, 1690, 1555, 1374, 1302, 1217, 1146,
˜
1098 cm–1. HRMS (LC-IT-TOF): calcd. for C28H24N2O6S2 [M + Na]+
571.0968; found 571.0977.
2,5-Bis(2-ethylhexyl)-3,6-bis[5-(1-octyl-1H-1,2,3-triazol-4-yl)- rated aqueous solution of NH4Cl (20 mL), and extracted with di-
thiophen-2-yl]pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (5a): Com-
pound 4a (73 mg, 0.13 mmol) and n-octyl azide (60 mg, 0.39 mmol)
were added at room temperature to a solution of Cu(OAc)2·H2O
(6 mg, 0.03 mmol) in H2O (10 mL) in a round-bottomed flask
equipped with a magnetic stirrer and a condenser. The mixture was
heated at 80 °C and vigorously stirred. Upon completion of the
chloromethane (3 × 40 mL). The combined organic extracts wasere
washed with an aqueous solution of NaCl (3 × 30 mL), dried with
Na2SO4, and concentrated under vacuum. The crude product was
purified by column chromatography on silica gel (hexane/ethyl
acetate/dichloromethane, 6:4:4; Rf = 0.58). A purple solid was iso-
lated (54 mg, 53 %), which was then crystallized from dichloro-
reaction (22 h; TLC analysis), the mixture was cooled to room tem- methane/hexane. Darkening of the product was observed upon
1
perature, then quenched with a saturated aqueous solution of
heating (m.p. > 300 °C). H NMR (400 MHz, CDCl3): δ = 8.28 (d, J =
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2625
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
4.0 Hz, 2 H), 7.76 (s, 2 H), 7.44 (d, J = 4.0 Hz, 2 H), 4.38 (t, J = 7.2 Hz,
4 H), 1.98–1.88 (m, 4 H), 1.61 (s, 18 H), 1.38–1.20 (m, 20 H), 0.86 (t,
J = 6.6 Hz, 6 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ = 159.1, 148.8,
141.7, 139.7, 137.3, 135.0, 128.7, 124.8, 120.1, 110.4, 86.1, 50.7, 31.7,
30.3, 29.0, 28.9, 27.8, 26.5, 22.6, 14.0 (one coincident signal not ob-
HRMS (LC-IT-TOF): calcd. for C50H74N8O10S2 [M + Na]+ 1033.4862;
found 1033.4858.
3,6-Bis{5-[1-(2-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}ethyl)-1H-
1,2,3-triazol-4-yl]thiophen-2-yl}-2,5-bis{2-[2-(2-methoxy-
ethoxy)ethoxy]ethyl}pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione
(5f): Compound 4b (51 mg, 0.08 mmol) and 2-{2-[2-(2-azido-
ethoxy)ethoxy]ethoxy}ethanol (53 mg, 0.24 mmol) were added at
room temperature to a solution of Cu(OAc)2·H2O (4 mg, 0.02 mmol)
in H2O (7 mL) in a round-bottomed flask equipped with a magnetic
stirrer and a condenser. The mixture was heated at 80 °C and vigor-
ously stirred. Upon completion of the reaction (22 h; TLC analysis),
the mixture was cooled to room temperature, then quenched with
H2O (30 mL), and extracted with a mixture of dichloromethane and
acetone (1:1; 4 × 50 mL). The combined organic extracts were
served) ppm. IR (KBr): ν = 3107, 2925, 2855, 1756, 1695, 1572, 1433,
˜
1294, 1253, 1148, 1093, 1057 cm–1. HRMS (LC-IT-TOF): calcd. for
C
44H58N8O6S2 [M + Na]+ 881.3813; found 881.3834.
3,6-Bis[5-(1-hexadecyl-1H-1,2,3-triazol-4-yl)thiophen-2-yl]-2,5-
bis{2-[2-(2-methoxyethoxy)ethoxy]ethyl}pyrrolo[3,4-c]pyrrole-
1,4(2H,5H)-dione (5d): Compound 4b (62 mg, 0.097 mmol) and n-
hexadecyl azide (78 mg, 0.29 mmol) were added at room tempera-
ture to a solution of Cu(OAc)2·H2O (4 mg, 0.02 mmol) in H2O (9 mL)
in a round-bottomed flask equipped with a magnetic stirrer and a
condenser. The mixture was heated at 80 °C and vigorously stirred.
Upon completion of the reaction (16 h; TLC analysis), the mixture
was cooled to room temperature, then quenched with a saturated
aqueous solution of NH4Cl (30 mL), and extracted with dichloro-
methane (3 × 50 mL). The combined organic extracts were washed
with an aqueous solution of NaCl (3 × 30 mL), dried with Na2SO4,
and concentrated under vacuum. The crude product was purified
by column chromatography on silica gel (CH2Cl2/acetone, 8:2; Rf =
0.82). A dark purple solid was isolated (83 mg, 73 %), which was
washed with an aqueous solution of 0.1
N EDTA (2 × 30 mL) and
H2O (1 × 30 mL), dried with Na2SO4, and concentrated under vac-
uum. The crude product was purified by crystallization from CH2Cl2/
hexane. A dark purple solid was isolated (68 mg, 79 %) [m.p. 95–
97 °C (dichloromethane/hexane)]. 1H NMR (400 MHz, CDCl3): δ =
8.83 (d, J = 4.0 Hz, 2 H), 8.13 (s, 2 H), 7.49 (d, J = 4.0 Hz, 2 H), 4.59
(t, J = 4.8 Hz, 4 H), 4.31 (t, J = 6.2 Hz, 4 H), 3.89 (t, J = 4.8 Hz, 4 H),
3.78 (t, J = 6.2 Hz, 4 H), 3.72–3.68 (m, 4 H), 3.67–3.52 (m, 32 H),
3.45–3.41 (m, 4 H), 3.29 (s, 6 H), 2.31 (br. s, 2 H) ppm. 13C NMR
(100.6 MHz, CDCl3): δ = 161.4, 141.7, 139.9, 138.8, 136.1, 128.6,
125.1, 121.9, 108.1, 72.4, 71.8, 70.7, 70.5, 70.5, 70.3, 70.2, 69.3, 69.0,
61.6, 58.9, 50.5, 41.9 (three coincident signals not observed) ppm.
1
then washed with methanol [m.p. 145–147 °C (methanol)]. H NMR
(400 MHz, CDCl3): δ = 8.82 (d, J = 4 Hz, 2 H), 7.79 (s, 2 H), 7.46 (d,
J = 4 Hz, 2 H), 4.36 (t, J = 7.4 Hz, 4 H), 4.29 (t, J = 6.0 Hz, 4 H), 3.78
(t, J = 6.2 Hz, 4 H), 3.65–3.60 (m, 4 H), 3.59–3.51 (m, 8 H), 3.45–3.41
(m, 4 H), 3.28 (s, 6 H), 1.97–1.87 (m, 4 H), 1.38–1.18 (m, 52 H), 0.84
(t, J = 6.8 Hz, 6 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ = 161.3,
141.7, 139.7, 138.5, 135.9, 128.7, 125.0, 120.0, 108.1, 71.8, 70.7, 70.5,
70.0, 58.9, 50.6, 41.9, 31.9, 30.2, 29.6, 29.6, 29.5, 29.5, 29.3, 29.3, 29.0,
26.4, 22.6, 14.1 (five coincident signals not observed) ppm. IR (KBr):
IR (KBr): ν = 3398, 2869, 1669, 1652, 1547, 1426, 1244, 1103, 1089,
˜
1066 cm–1. HRMS (LC-IT-TOF): calcd. for C48H70N8O16S2 [M + Na]+
1101.4243; found 1101.4213.
Acknowledgments
ν = 3112, 2915, 2850, 1656, 1555, 1432, 1247, 1117, 1068 cm–1
.
˜
This work was financially supported by the Ministero dell'Istruzi-
one, dell'Università e della Ricerca (MIUR) [Progetto PRIN 2012
prot. 2012A4Z2RY”, “Project PON02_00563_3316357 (PON
MAAT), and Project PON03PE_00004_1 (PON MAIND)]. This
work was also supported by the Dirección General de Investiga-
ción y Gestión del Plan Nacional de I+D+i (DGI) of the Ministerio
de Ciencia y Tecnología (Spain) (Grant BE-WELL CTQ2013-
40480-R), Agència de Gestió d'Ajuts Universitaris i de Recerca
(AGAUR), Generalitat de Catalunya (Grant 2014-SGR-17), and the
Networking Research Center on Bioengineering, Biomaterials,
and Nanomedicine (CIBER-BBN). D. B. and A. A. acknowledge
the European Commission (EC) FP7-PEOPLE-2013-Initial Train-
ing Networks (ITN) (NANO2FUN Project No. 607721) for their
predoctoral contracts.
HRMS (LC-IT-TOF): calcd. for C64H102N8O8S2 [M + Na]+ 1197.7154;
found 1197.7175.
2,5-Bis(2-ethylhexyl)-3,6-bis{5-[1-(2-{2-[2-(2-hydroxyethoxy)-
ethoxy]ethoxy}ethyl)-1H-1,2,3-triazol-4-yl]thiophen-2-
yl}pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (5e): Compound 4a
(82 mg, 0.14 mmol) and 2-{2-[2-(2-azidoethoxy)ethoxy]ethoxy}-
ethanol (100 mg, 0.46 mmol) were added at room temperature to
a solution of Cu(OAc)2·H2O (8 mg, 0.04 mmol) in H2O (15 mL) in
a round-bottomed flask equipped with a magnetic stirrer and a
condenser. The mixture was heated at 100 °C and vigorously stirred.
Upon completion of the reaction (20 h; TLC analysis), the mixture
was cooled to room temperature, then quenched with a saturated
aqueous solution of NH4Cl (30 mL), and extracted with dichloro-
methane (3 × 50 mL). The combined organic extracts were washed
with an aqueous solution of NaCl (3 × 30 mL), dried with Na2SO4,
and concentrated under vacuum. The crude product was purified
by column chromatography on silica gel [CH2Cl2/ethyl acetate/
methanol, 5:5:1 to 5:5:3; Rf (CH2Cl2/ethyl acetate/methanol, 5:5:3) =
0.53]. After washing with hexane, a dark purple solid was isolated
(99 mg, 70 %), which was then crystallized from dichloromethane/
hexane [m.p. 120–121 °C (dichloromethane/hexane)]. 1H NMR
(400 MHz, CDCl3): δ = 8.92 (d, J = 4.0 Hz, 2 H), 8.11 (s, 2 H), 7.46 (d,
J = 4.0 Hz, 2 H), 4.58 (t, J = 4.8 Hz, 4 H), 4.09–3.98 (m, 4 H), 3.88 (t,
J = 4.8 Hz, 4 H), 3.69 (t, J = 4.6 Hz, 4 H), 3.66–3.55 (m, 20 H), 2.70
(br. s, 2 H), 1.96–1.85 (m, 2 H), 1.43–1.15 (m, 16 H), 0.86 (t, J = 7.4 Hz,
6 H), 0.81 (t, J = 6.8 Hz, 6 H) ppm. 13C NMR (100.6 MHz, CDCl3): δ =
161.7, 141.8, 140.1, 138.7, 136.4, 128.8, 125.0, 121.8, 108.3, 72.4, 70.5,
70.5, 70.3, 70.2, 69.4, 61.6, 50.5, 46.1, 39.1, 30.1, 28.3, 23.6, 23.0, 14.0,
Keywords: Azides · Click chemistry · Conjugation · Dyes/
Pigments · Nitrogen heterocycles
[1] For a review on supramolecular assemblies of π-conjugated systems, see:
F. J. M. Hoeben, P. Jonkheijm, E. W. Meijer, A. P. H. J. Schenning, Chem.
Rev. 2005, 105, 1491–1546.
[2] a) A. Operamolla, G. M. Farinola, Eur. J. Org. Chem. 2011, 423–450; b)
J. A. Paulson, A. Mesbah, X. Zhu, M. C. Molaro, R. D. Braatz, J. Process
Control 2015, 27, 38–49.
[3] a) L. Chiavarone, M. Di Terlizzi, G. Scamarcio, F. Babudri, G. M. Farinola, F.
Naso, Appl. Phys. Lett. 1999, 75, 2053–2055; b) M. Losurdo, M. M. Giangre-
gorio, P. Capezzuto, G. Bruno, F. Babudri, A. Cardone, C. Martinelli, G. M.
Farinola, F. Naso, M. Büchel, Polymer 2008, 49, 4133–4140; c) M. Losurdo,
M. M. Giangregorio, P. Capezzuto, A. Cardone, C. Martinelli, G. M. Farinola,
10.5 (one coincident signal not observed) ppm. IR (KBr): ν = 3443,
˜
3120, 2947, 2925, 2867, 1641, 1540, 1432, 1245, 1088, 1059 cm–1
.
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2626
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
F. Babudri, F. Naso, M. Büchel, G. Bruno, Adv. Mater. 2009, 21, 1115–1120;
d) G. Pescitelli, O. Omar Hassan, A. Operamolla, G. M. Farinola, L. Di Bari,
Macromolecules 2012, 45, 9626–9630; e) R. Rybakiewicz, J. Zapala, D.
Djurado, R. Nowakowski, P. Toman, J. Pfleger, J.-M. Verilhac, M. Zagorska,
A. Pron, Phys. Chem. Chem. Phys. 2013, 15, 1578–1587; f) L. Liao, X.
Zhang, F. Hu, S. Wang, S.-D. Xu, Q. Zeng, C. Wang, J. Phys. Chem. C 2014,
118, 7989–7995; g) L. Xu, D. Gao, J. Song, L. Shen, W. Chen, Y. Chen, S.
Zhang, New J. Chem. 2015, 39, 5553–5560; h) Y. Gao, G. Feng, T. Jiang,
C. Goh, L. Ng, B. Liu, B. Li, L. Yang, J. Hua, H. Tian, Adv. Funct. Mater.
2015, 25, 2857–2866.
Marchese, A. Punzi, F. Capuzzolo, Tetrahedron 2009, 65, 10573–10580; c)
V. Fiandanese, G. Marchese, A. Punzi, F. Iannone, G. G. Rafaschieri, Tetra-
hedron 2010, 66, 8846–8853; d) V. Fiandanese, F. Iannone, G. Marchese,
A. Punzi, Tetrahedron 2011, 67, 5254–5260; e) V. Fiandanese, S. Mauranto-
nio, A. Punzi, G. G. Rafaschieri, Org. Biomol. Chem. 2012, 10, 1186–1195;
f) V. Fiandanese, I. Marino, A. Punzi, Tetrahedron 2012, 68, 10310–10317.
a) V. V. Rostovtsev, L. G. Green, V. V. Fokin, K. B. Sharpless, Angew. Chem.
Int. Ed. 2002, 41, 2596–2599; Angew. Chem. 2002, 114, 2708–2711; b)
C. W. Tornøe, C. Christensen, M. Meldal, J. Org. Chem. 2002, 67, 3057–
3064.
[14]
[4] For a review on DPP-based fluorescent probes, see: M. Kaur, D. H. Choi,
Chem. Soc. Rev. 2015, 44, 58–77.
[5] E. H. G. Zadeh, M. V. Bondar, I. A. Mikhailov, K. D. Belfield, J. Phys. Chem.
C 2015, 119, 8864–8875.
[6] a) M. Fukuda, K. Kodama, H. Yamamoto, K. Mito, Dyes Pigm. 2004, 63,
115–125; b) S. Mula, D. Hablot, K. K. Jagtap, E. Heyer, R. Ziessel, New J.
Chem. 2013, 37, 303–308.
[15]
[16]
H. C. Kolb, M. G. Finn, K. B. Sharpless, Angew. Chem. Int. Ed. 2001, 40,
2004–2021; Angew. Chem. 2001, 113, 2056–2075.
For recent reviews, see: a) A. Qin, J. W. Y. Lambc, B. Z. Tang, Chem. Soc.
Rev. 2010, 39, 2522–2544; b) E. Lallana, R. Riguera, E. Fernandez-Megia,
Angew. Chem. Int. Ed. 2011, 50, 8794–8804; Angew. Chem. 2011, 123,
8956–8966; c) A. Lauria, R. Delisi, F. Mingoia, A. Terenzi, A. Martorana, G.
Barone, A. M. Almerico, Eur. J. Org. Chem. 2014, 3289–3306; d) B. Schul-
zeab, U. S. Schubert, Chem. Soc. Rev. 2014, 43, 2522–2571; e) W. Xi, T. F.
Scott, C. J. Kloxin, C. N. Bowman, Adv. Funct. Mater. 2014, 24, 2572–2590;
f) S. Kantheti, R. Narayana, K. V. S. N. Raju, RSC Adv. 2015, 5, 3687–3708.
a) E. Heyer, P. Lory, J. Leprince, M. Moreau, A. Romieu, M. Guardigli, A.
Roda, R. Ziessel, Angew. Chem. Int. Ed. 2015, 54, 2995–2999; Angew.
Chem. 2015, 127, 3038–3042; b) M. Grzybowski, E. Glodkowska-Mrowka,
V. Hugues, W. Brutkowski, M. Blanchard-Desce, D. T. Gryko, Chem. Eur. J.
2015, 21, 9101–9110; c) Y. Hang, L. Yang, Y. Qub, J. Hua, Tetrahedron Lett.
2014, 55, 6998–7001.
C. M. Cardona, W. Li, A. E. Kaifer, D. Stockdale, G. C. Bazan, Adv. Mater.
2011, 23, 2367–2371.
M. Kirkus, L. Wang, S. Mothy, D. Beljonne, J. Cornil, R. A. J. Janssen, S. C. J.
Meskers, J. Phys. Chem. A 2012, 116, 7927–7936.
J. S. Zambounis, Z. Hao, A. Iqbal, Nature 1997, 388, 131–132.
a) J. Lee, A.-R. Han, J. Hong, J. Hwa Seo, J. H. Oh, C. Yang, Adv. Funct.
Mater. 2012, 22, 4128–4138; b) Y. Suna, J. Nishida, Y. Fujisaki, Y. Yama-
shita, Org. Lett. 2012, 14, 3356–3359; c) B. Sun, W. Hong, H. Azizbc, Y. Li,
J. Mater. Chem. 2012, 22, 18950–18955.
[7] Z. Qiao, Y. Xu, S. Lin, J. Peng, D. Cao, Synth. Met. 2010, 160, 1544–1550.
[8] For recent reviews on DPP derivatives in organic electronics, see: a) S.
Qua, H. Tian, Chem. Commun. 2012, 48, 3039–3051; b) C. B. Nielsen, M.
Turbiez, I. McCulloch, Adv. Mater. 2013, 25, 1859–1880; c) J. D. Yuen, F.
Wuld, Energy Environ. Sci. 2013, 6, 392–406; d) Y. Li, P. Sonar, L. Murphya,
W. Honga, Energy Environ. Sci. 2013, 6, 1684–1710; e) D. Chandran, K.-S.
Lee, Macromol. Res. 2013, 21, 272–283; f) A. M. Naik, S. Patil, J. Polym.
Sci., Part A 2013, 51, 4241–4260.
[9] a) O. P. Lee, A. T. Yiu, P. M. Beaujuge, C. H. Woo, T. W. Holcombe, J. E.
Millstone, J. D. Douglas, M. S. Chen, J. M. J. Fréchet, Adv. Mater. 2011, 23,
5359–5363; b) M. A. Naik, N. Venkatramaiah, C. Kanimozhi, S. Patil, J.
Phys. Chem. C 2012, 116, 26128–26137; c) J. H. Seo, Synth. Met. 2012,
162, 748–752; d) C. Kanimozhi, N. Yaacobi-Gross, E. K. Burnett, A. L. Bris-
eno, T. D. Anthopoulos, U. Salznerd, S. Patil, Phys. Chem. Chem. Phys.
2014, 16, 17253–17265.
[10] a) C. Kanimozhi, N. Yaacobi-Gross, K. W. Chou, A. Amassian, T. D. Antho-
poulos, S. Patil, J. Am. Chem. Soc. 2012, 134, 16532–16535; b) J. Me, K. R.
Graham, R. Stalde, S. P. Tiwari, H. Cheun, J. Shim, M. Yoshi, C. Nuckolls, B.
Kippelen, R. K. Castellano, J. R. Reynolds, Chem. Mater. 2011, 23, 2285–
2288; c) W.-H. Chang, J. Gao, L. Dou, C.-C. Chen, Y. Liu, Y. Yang, Adv.
Energy Mater. 2014, 4, 1300864.
[11] a) G. Zhang, H. Li, S. Bi, L. Song, Y. Lu, L. Zhang, J. Yu, L. Wang, Analyst
2013, 138, 6163–6170; b) G. Zhang, S. Bi, L. Song, F. Wang, J. Yu, L. Wang,
Dyes Pigm. 2013, 99, 779–786; c) H. Ftouni, F. Bolze, J.-F. Nicoud, Dyes
Pigm. 2013, 97, 77–83; H. Ftouni, F. Bolze, H. de Rocquigny, J.-F. Nicoud,
Bioorg. Chem. 2013, 24, 942–950; d) A. Nowak-Krol, M. Grzybowski, J.
Romiszewski, M. Drobizhev, G. Wicks, M. Chotkowski, A. Rebane, E.
Gorecka, D. T. Gryko, Chem. Commun. 2013, 49, 8368–8370; e) G. Zhang,
L. Song, S. Bi, Y. Wu, J. Yu, L. Wang, Dyes Pigm. 2014, 102, 100–106; f) J.
Schmitt, V. Heitz, A. Sour, F. Bolze, H. Ftouni, J.-F. Nicoud, L. Flamigni, B.
Ventura, Angew. Chem. Int. Ed. 2015, 54, 169–173; Angew. Chem. 2015,
127, 171–175.
[17]
[18]
[19]
[20]
[21]
[22] K. Li, B. Liu, Chem. Soc. Rev. 2014, 43, 6570–6597.
[23] K. Pu, J. Mei, J. V. Jokerst, G. Hong, A. L. Antaris, N. Chattopadhyay, A. J.
Shuhendler, T. Kurosawa, Y. Zhou, S. S. Gambhir, Z. Bao, J. Rao, Adv. Mater.
2015, 27, 5184–5190.
[24] a) K. D. Belfield, M. V. Bondar, F. E. Hernandez, O. V. Przhonska, S. Yao,
Chem. Phys. 2006, 320, 118–124; b) S. Biswas, H. Ahn, M. V. Bondar, K. D.
Belfield, Langmuir 2012, 28, 1515–22; c) P. Hanczyc, A. Justyniarski, D. A.
Gedefaw, M. R. Andersson, M. Samoc, C. Müller, RSC Adv. 2015, 5, 49363–
49368; d) X. Shi, Z. Xu, Q. Liao, Y. Wu, Z. Gu, R. Zheng, H. Fu, Dye. Pigment.
2015, 115, 211–217.
[25] L. Hou, J. Hou, H. Chen, S. Zhang, Y. Jang, T. L. Chen, Y. Yang, Macromole-
cules 2009, 42, 6564–6571.
[26] A. B. Tamayo, B. Walker, T.-Q. Nguyen, J. Phys. Chem. C 2008, 112, 11545–
11551.
[27] Y. Yuan, T. Michinobu, J. Oguma, T. Kato, K. Miyake, Macromol. Chem.
Phys. 2013, 214, 1465–1472.
[12] a) Y. Bourne, H. C. Kolb, Z. Radic, K. B. Sharpless, P. Taylor, P. Marchot, Proc.
Natl. Acad. Sci. USA 2004, 101, 1449–1454; b) M. Whiting, J. Muldoon, Y.-
C. Lin, S. M. Silverman, W. Lindstrom, A. J. Olson, H. C. Kolb, M. G. Finn,
K. B. Sharpless, J. H. Elder, V. V. Fokin, Angew. Chem. Int. Ed. 2006, 45,
1435–1439; Angew. Chem. 2006, 118, 1463–1467.
[13] a) V. Fiandanese, D. Bottalico, G. Marchese, A. Punzi, M. R. Quarta, M.
Received: February 2, 2016
Fittipaldi, Synthesis 2009, 3853–3859; b) V. Fiandanese, D. Bottalico, G.
Published Online: April 26, 2016
Eur. J. Org. Chem. 2016, 2617–2627
www.eurjoc.org
2627
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim