Dual emissive bodipy-benzodithiophene-bodipy TICT triad with a remarkable Stokes shift of 194 nm

Article abstract of DOI:10.1039/c8ob00272j

An acceptor-donor-acceptor (A-D-A) triad based on a BODIPY acceptor and a benzodithiophene donor exhibited dual fluorescence and pronounced fluorescence solvatochromism because of twisted intramolecular charge transfer (TICT) state formation. Furthermore,

Full text of DOI:10.1039/c8ob00272j

View Article Online
View Journal
Organic &
Biomolecular
Chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Sengupta and
U. K. Pandey, Org. Biomol. Chem., 2018, DOI: 10.1039/C8OB00272J.
This is an Accepted Manuscript, which has been through the
Volume 14 Number
1 7 January 2016 Pages 1–372
Royal Society of Chemistry peer review process and has been
accepted for publication.
Organic &
Biomolecular
Chemistry
www.rsc.org/obc
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1477-0520
COMMUNICATION
Takeharu Haino et al.
Solvent-induced emission of organogels based on tris(phenylisoxazolyl)
benzene
rsc.li/obc

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 1 of 5
View Article Online
DOI: 10.1039/C8OB00272J
Organic & Biomolecular Chemistry
COMMUNICATION
Dual Emissive Bodipy-Benzodithiophene-Bodipy TICT Triad
with Remarkable Stokes Shift of 194 nm
cReceived 00th January 201x,
Accepted 00th January 201x
DOI: 10.1039/x0xx00000x
www.rsc.org/
Sanchita Senguptaa,b*, Upendra K. Pandeya
on BDT donors and BODIPY acceptor, T1 and T2 (Figure 1) that
showed efficient photoinduced electron transfer (PET) and
possess appreciable charge carrier mobilities.30 D-A systems
composed of BDT and BODIPY usually absorb in the ultraviolet
(UV) and the visible region with spectral coverage of upto ~ 700
nm as a result of intramolecular charge transfer.13 Density
functional theory (DFT) calculations revealed that the optical
and redox properties can be extensively tuned either by
changing substituents or by tuning the coupling position of BDT
donor at either meso position or at α/β positions of BODIPY. But
An acceptor-donor-acceptor (A-D-A) triad based on BODIPY
acceptor and benzodithiophene donor exhibited dual
fluorescence and pronouned fluorescence solvatochromism
because of twisted intramolecular charge transfer (TICT)
state formation. Furthermore, it showed a Stokes shift of ~
194 nm which is highest known for any BODIPY compound
with readily tunable fluorescence and high charge carrier
mobility of 4.46 × 10-4 cm2/Vs.
Molecular design of twisted donor-acceptor (D-A) systems reports of BODIPY based TICT and AIE systems are rather
largely govern their photophysical properties in solution1–4 such scarce.31,32
as excimer formation,2 twisted intramolecular charge transfer
Herein, we report the design, synthesis and
(TICT) states5,6 and aggregate induced emission (AIE).7–11 photophysical properties of a new acceptor-donor-acceptor
Excimer emission in BODIPY12 based D-A molecules and their triad system A-D-A (Figure 1) based on BODIPY acceptor
dimeric systems have been vastly explored.2,13 Depending upon and BDT donor whereby the BODIPY units are attached
geometry and twisting of the D-A backbone and their decoupling through their meso positions and are decoupled from the
by spacer units, they show intense solvatochromism14,15 as well donor units by two flexible phenyl spacers. We intend to
as exciplex formation,16,17 mechanofluorochromism,18,19 AIE7 or study the optical properties of A-D-A compared to the
TICT states.20 Hence, judicious molecular engineering of D-A previously studied D-A-D compounds that showed efficient
system with spacer unit that decouples the donor and acceptor PET.30 The photophysical properties of A-D-A triad were
should lead to new fluorescence probes with interesting investigated using steady state absorption, fluorescence
photophysical phenomena such as TICT and AIE. TICT property spectroscopy, fluorescence lifetimes and solvatochromism.
can be exploited for designing new materials with potential Moreover, charge carrier mobility of this material was
applications in chemosensors, in lighting and display such as investigated in order to assess its suitability for
organic light emitting diodes (OLEDs)21–23, non linear optics24 optoelectronic applications.
and optical waveguides. Moreover, such systems could have
potential applications in biomedical imaging25, optoelectronic
devices such as in organic photovoltaics (OPV).26
Benzodithiophene (BDT) is an interesting candidate for OPV
applications owing to their planar structure, deep lying HOMO
levels and reportedly high hole mobilities as well as high power
conversion efficiencies (PCEs) in organic and polymer solar
cells.27–29 Recently, we reported regioisomeric D-A triads based
aInterdisciplinary Centre for Energy Research (ICER)
Indian Institute of Science (IISc) Bangalore
C. V. Raman Road, Bangalore 560012, Karnataka, India.
Present Address: bDepartment of Chemical Sciences, Indian Institute of Science
Education and Research (IISER) Mohali
Sector 81, Knowledge City, P.O. Manauli 140306, Punjab, India.
E-mail: sanchita@iisermohali.ac.in
Electronic Supplementary Information (ESI) available: Synthesis details,
compound characterization and spectroscopic characterization.
Fig 1. Molecular triad(s) newly synthesized (A-D-A) and investigated (T-
1, T-2 and A-D-A) in this work.
See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 2018
J. Name., 2018, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 2 of 5
View Article Online
DOI: 10.1039/C8OB00272J
Organic & Biomolecular Chemistry
COMMUNICATION
The synthesis of A-D-A was carried out as outlined in The highest occupied molecular orbital (HOMO) and lowest
Scheme 1. BODIPY was synthesized starting from 4- unoccupied molecular orbital (LUMO) levels of A-D-A were
4
bromobenzaldehyde and pyrrole in presence of catalytic calculated by density functional theory (DFT) method using
amount of HCl in an aqueous media according to a reported Gaussian 09 package by B3LYP/6-31G(d,p) method.36 For A-D-A,
procedure34,35 for
a different dipyrromethane (DPM) HOMO is entirely localized on the BDT unit and the LUMO is
compound. However, it is to be noted here that this reaction entirely localized on BODIPY with no overlap between the
in an aqueous medium has not been used for the synthesis HOMO and LUMO (Fig. 3). Hence, no electronic communication
of DPM
3 and BODIPY 4 earlier to the best of our was observed between BDT and BODIPY that is in agreement
knowledge. This method34 was advantageous in terms of with the experimental absorption spectrum of A-D-A. The
yield (78 %) compared to the conventional route of corresponding frontier molecular orbital (FMO) energies are
condensation of pyrrole with aldehyde in presence of presented in Table S1. Geometry optimization was carried out
catalytic amount of trifluoroacetic acid (TFA). Distannylated on A-D-A structure and torsion angles between BODIPY and
BDT (
5) was synthesized according to previously reported phenyl spacer and between phenyl spacer and BDT unit were
procedure (see ESI).33 Synthesis of A-D-A was achieved by
54.1° and 32.2° respectively, which render the molecule non-
planar. Furthermore, charge distribution calculations were
performed including dipole moments for the ground state
and the excited state of A-D-A. Notably, the ground state
Stille coupling of 422 (2 eq.) and
catalytic amounts of
acetone)dipalladium(0), Pd2(dba)3 and tri(o-tolyl)phosphine
5
in dry toluene with
tris(dibenzylidene-
28
P(o-tol)3 and A-D-A was isolated in 56 % yield (ESI for
details).
dipole moment of 1.28 D was obtained for A-D-A whereas
dipole moment of the first excited state obtained was much
higher ~ 1.94 D. This difference in dipole moments in ground
and excited state has important consequences in the optical
properties of A-D-A as will be discussed (vide infra).
Fig 3. Optimized structure of A-D-A showing dihedral angles in top view
and side view showing phenyl groups twisted out of the plane of the
structure.
Cyclic voltammetry (CV) measurements were performed to
determine the frontier orbital energy levels of A-D-A. Based on
the first oxidation potential onset (Eoxonset) and first reduction
potential (Eredonset), the HOMO was calculated as, HOMO = −
Scheme 1. Synthesis of BDT-BODIPY triad A-D-A.
Fig. 2 shows the UV/Vis absorption spectra of model acceptor
and donor compounds 4 and 5 and triad A-D-A in DCM. Donor 5
has absorption maximum at 372 nm while the absorption (Eox
+ 4.76) eV37 and LUMO = − (Ered
+ 4.76) eV as
onset
onset
maximum for acceptor 4 occurs at 504 nm. The absorption
spectrum of A-D-A is merely the sum of D and A absorption i.e.,
absorption maxima at 315 nm, 380 nm for the BDT donor and at
503 nm for the BODIPY unit, indicative of no electronic
communication between the donor and acceptor components.
summarized in Table S1. Accordingly, calculated HOMO and
LUMO levels at ~ -5.86 eV and ~ -3.89 eV were obtained
respectively for A-D-A. Fluorescence emission spectra of A-D-A
(Fig. 4a) was measured upon three different excitations at 315
nm, 380 nm (donor) and 503 nm (acceptor) respectively.
Notably, upon excitation at 315 nm and 380 nm, apart from the
donor emission at 405 nm, a broad but intense emission was
observed at
~ 698 nm which is attributed to a twisted
intramolecular charge transfer state (TICT) state. Interestingly, a
pseudo Stokes shift of ~ 194 nm (51546 cm–1) was obtained
which is remarkable and much higher than previous reports of
high Stokes shifts for BODIPY compounds.38–40 Fluorescence
quantum yield was determined by absolute method using an
integrating sphere set-up upon excitation at 383 nm and a
quantum yield of ~ 0.03 was obtained for A-D-A (Table S2 in
supporting information). The formation of TICT state is further
justified by the high twist angles (BDP-phenyl and phenyl-BDT)
in the structure as well as the difference in the DFT calculated
dipole moments of ground state and first excited state. These
dissimilar dipole moments lead to the preferential stabilization
Fig 2. UV-Vis absorption spectra of model compounds 5, 4 and triad A-D-
A in DCM.
This journal is © The Royal Society of Chemistry 2018
J. Name., 2018, 00, 1-3 | 2
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 3 of 5
View Article Online
DOI: 10.1039/C8OB00272J
Organic & Biomolecular Chemistry
COMMUNICATION
of the excited state dipole over the ground state dipole of A-D-A
in polar solvents. Therefore, the fluorescence shows
bathochromic shift in solvents of increasing polarity.14 Solvent
dependent emission spectra were recorded for A-D-A (Fig. 4b)
that showed significant bathochromic shift of the emission
maximum from 549 nm in toluene to 647 nm in chloroform (CF)
and 700 nm in DCM.
emission bands at 726 nm and 729 nm were studied for T1
and T2 respectively. The decay lifetime for the CT band of
T2 was ~ 0.46 ns corresponding to a much faster decay
compared to that of T1 for which a longer lifetime of ~ 3.16
ns was obtained (see supplementary information for
fluorescence decays, fitted parameters and lifetime values).
The faster decay and the shorter lifetime values for T2
reflect that PET is more efficient in it than that for T1
.
Furthermore, it is noteworthy that the lifetime of T1 (~
3.16 ns) was marginally shorter than the lifetime of A-D-A
(~ 3.41 ns) which corroborates the fact that TICT state
formation in A-D-A is a slower process compared to PET
that is occurring in T1 41
.
The formation of TICT state takes place in polar solvents and
the TICT state reverses to the local excited (LE) state as the
solvent polarity is reduced.13 Emission measurements were
performed in solvents of gradually decreasing polarity starting
from 100 % THF upto 99/1 (v/v) hexane/THF. The formation of
TICT in A-D-A was justified by the fluorescence spectrum
showing an emission maximum at 650 nm. Upon reduction of
the solvent polarity by gradual addition of hexane, the emission
maximum shifted hypsochromically indicative of the formation
of a LE state. Fig 6a shows the shift of emission maximum of A-
D-A from 650 nm in 100 % THF to 523 nm in 99/1 (v/v)
hexane/THF.
Fig 4. a) Fluorescence emission spectra of A-D-A in DCM; b)
Fluorescence emission spectra of A-D-A upon excitation at 380 nm in
acetonitrile (ACN), chlorobenzene (CB), chloroform (CF), ethanol (EtOH),
toluene (Tol) and DCM.
Such pronounced positive solvatochromism is attributed to
increased stabilization of a polar TICT state in polar solvents
compared to
a less polar ground state. Notably, UV-Vis
absorption of A-D-A in the same solvents did not show any
noticeable change, which is consistent with the fact that the
ground state of A-D-A is less polar than the excited state.
Fluorescence lifetime measurements were performed for donor
5 and A-D-A in CF using time correlated single photon counting
(TCSPC) measurement technique. The fluorescence lifetimes of
donor D was measured upon excitation at 374 nm and the decay
was fast with a short lifetime of ~ 0.47 ns. Fluorescence lifetime
of A-D-A was measured upon excitation wavelength of 374 nm
and decay profiles at emission wavelengths of 410 nm
(corresponding to donor decay) and TICT emission at 700 nm
were studied. The CT emission decay is known to exhibit longer
rise time that is characteristic of charge transfer and a slow
component, which is characteristic of the lifetime of the
T
riads T1 and T2 both showed ICT bands and electron
transfer was more efficient in case of T2 owing to its planar
conformation. Interestingly, emission spectra of T1 in
hexane/THF solvent mixtures showed a negligible hypsochromic
shift in fluorescence upon going from 100 % THF to increasing
percentage of hexane in the hexane/THF mixtures. A negligible
shift of ~ 4-5 nm was observed which is attributed to the fact
that the D and A units directly connected in T1 without a phenyl
spacer led to restricted rotation of the units leading to no
significant solvatochromism (see supplementary information).
In the case of T2, fluorescence was severely quenched as a result
of efficient electron transfer.
Aggregate induced emission (AIE) is a highly desirable
property for D-A compounds separated by spacer unit(s) for
their potential application in OLEDs.7,8 AIE property was
investigated in A-D-A by measuring fluorescence in solvent
mixtures of water and THF. Upon increasing fraction percentage
of water (fw) (from 0% to 10% to 30% upto 50 %), overall
increased solvent polarity twisted the molecule and therefore
equilibrated molecules.13 Accordingly,
a slower decay was
observed for A-D-A emission at 700 nm with a fluorescence
lifetime of ~3.41 ns as shown in Fig. 5a. Notably, the decay for
the donor emission band of A-D-A at 410 nm was also fast with a
lifetime of ~ 0.79 ns which corresponds closely to that of the
neat donor 5. Fluorescence lifetime of A-D-A was also evaluated
upon excitation at 469 nm and the lifetime of the TICT band at
700 nm was similar ~ 3.40 ns (Table S3 for fluorescence decays,
fitted parameters and lifetime values).
shifted the equilibrium towards TICT state leading to
a
bathochromic shift from 645 nm to 657 nm. However, it is worth
noting that the fluorescence intensity is severely quenched at
30% fw and 50% fw mixtures (Figure 6b). Upon increasing the fw
to 75% and 90 %, A-D-A preferably forms nanoclusters leading
to restricted intramolecular rotation that renders the
Fig 5. Fluorescence decay plots along with fitted data of a) triad A-
D-A upon excitation at 374 nm and 469 nm; b) T1 and T2 upon equilibrium shift towards LE state. Thus, in these two solvent
excitation at 374 nm and 669 nm
In order to understand the difference in the photophysics of
A-D-A and previously reported regioisomers T1 and T2
fluorescence lifetime measurements for T1 and T2 were
performed. Lifetime measurements were carried out in CF
upon excitation at 374 nm and 669 nm and the decay of
.
mixtures (75% fw and 90% fw), hypsochromic shift of emission
maximum at 633 nm was observed along with an increased
fluorescence intensity (Figure 6b) because restricted motion
lowered the pathways for non-radiative decay.
,
This journal is © The Royal Society of Chemistry 2018
J. Name., 2018, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 4 of 5
View Article Online
DOI: 10.1039/C8OB00272J
Organic & Biomolecular Chemistry
COMMUNICATION
applications such as in OLEDs and in OPV. At present, similar
TICT based new molecules are being designed and their utility in
(opto)electronic applications are being explored.
This work was financially supported by the Department of
Science of Technology (DST) of India under INSPIRE Faculty
fellowship award (No. DSTO1267 and DSTO1286). Mass
spectrometry facility at Molecular Biophysics Unit (MBU), Indian
Institute of Science is gratefully acknowledged. Spectroscopy
and analytical test facility at IISc Bangalore is gratefully
acknowledged for providing accessibility to TCSPC
measurements.
Fig 6. a) Emission spectra of A-D-A in THF and THF/hexane mixtures
with increasing volume percentages of hexane showing the formation of
TICT state; b) AIE formation in A-D-A in various weight fractions of
water and THF.
Notes and references
In order to assess the inherent charge transport properties of A-
D-A, its hole mobility was measured using space charge limited
current (SCLC) method.42,43 Hole only device architecture of
ITO/PEDOT:PSS/active layer (A-D-A)/Au was used to perform J-
V characteristics in dark (see ESI†). Hole mobility of A-D-A was
extracted from the SCLC region of the curve as shown in Fig. 7.
Hole mobility of 4.46 × 10-4 cm2/Vs was obtained for A-D-A.
Higher mobility of A-D-A compared to the triads reported earlier
(7.01 × 10-5 cm2/Vs and 3.63 × 10-4 cm2/Vs for T1 and T2
respectively)30 can be attributed to the structure of A-D-A where
electronically inactive alkyl chains are much less compared to
those in the triads T1 and T230 and consequently leads to better
packing in films.
1
2
S. Sasaki, G. P. C. Drummen and G. Konishi, J. Mater. Chem.
C, 2016, 4, 2731–2743.
M. A. H. Alamiry, A. C. Benniston, G. Copley, A. Harriman
and D. Howgego, J. Phys. Chem. A, 2011, 115, 12111–
12119.
3
4
5
6
7
8
9
J. Verhoeven, Photochem. Photobiol. Sci., 2010, 9, 1009–
1017.
Z. R. Grabowski, K. Rotkiewicz and W. Rettig, Chem. Rev.,
2003, 103, 3899–4032.
S. Sasaki, Y. Niko, A. S. Klymchenko and G. I. Konishi,
Tetrahedron, 2014, 70, 7551–7559.
H. Tanaka, K. Shizu, H. Nakanotani and C. Adachi, Chem.
Mater., 2013, 25, 3766–3771.
Y. Hong, J. W. Y. Lam and B. Z. Tang, Chem. Soc. Rev., 2011,
40, 5361–5388.
J. Mei, Y. Hong, J. W. Y. Lam, A. Qin, Y. Tang and B. Z. Tang,
Adv. Mater., 2014, 26, 5429–5479.
J. Shi, N. Chang, C. Li, J. Mei, C. Deng, X. Luo, Z. Liu, Z. Bo, Y.
Q. Dong and B. Z. Tang, Chem. Commun., 2012, 48, 10675-
10677.
10
H. Tsujimoto, D.-G. Ha, G. Markopoulos, H. S. Chae, M. A.
Baldo and T. M. Swager, J. Am. Chem. Soc., 2017, 139,
4894-4900.
Fig 7. Dark J-V curve for triad A-D-A with a film thickness of 110 nm; the
solid red line is the SCLC fit of the experimental data.
11
12
13
Y. Hong, J. W. Y. Lam and B. Z. Tang, Chem. Commun.,
2009, 4332-4353.
In summary, a new acceptor-donor-acceptor triad A-D-A based
on BODIPY acceptor and BDT donor separated by phenyl spacers
was synthesized that showed no ground state interaction
between BODIPY and BDT units and spectral coverage till 550
nm. Interestingly, A-D-A showed dual emission with emission
maximum at 700 nm that resulted due to the formation of a TICT
state with a pseudo-Stokes shift of ~ 194 nm. Furthermore,
pronounced positive fluorescence solvatochromism was
observed in solvents of increasing polarities due to the
formation of TICT state. The formation of TICT state was further
evident from emission measurements in solvent mixture of THF
and hexane where a hypsochromic shift in emission of ~ 127 nm
was observed upon going from 100 % THF upto 99/1 (v/v)
hexane/THF. Aggregate induced emission was observed for A-D-
A in solvent mixtures of hexane/water with emission intensity
and wavelength varying with increasing percentage of water
indicating it suitability for possible OLED applications. Finally,
high hole mobility of A-D-A of 4.45 × 10-4 cm2/Vs was obtained
that justified the suitability of this triad for (opto)electronic
A. Loudet and K. Burgess, Chem. Rev., 2007, 107, 4891–
4932.
R. Hu, E. Lager, A. Aguilar-Aguilar, J. Liu, J. W. Y. Lam, H. H.
Y. Sung, I. D. Williams, Y. Zhong, K. S. Wong, E. Peña-
Cabrera and B. Z. Tang, J. Phys. Chem. C, 2009, 113, 15845–
15853.
14
15
C. Reichardt, Chem. Rev., 1994, 94, 2319–2358.
A. Filarowski, M. Lopatkova, P. Lipkowski, M. Van der
Auweraer, V. Leen and W. Dehaen, J. Phys. Chem. B., 2015,
119, 2576–2584.
16
17
18
19
A. C. Benniston, G. Copley, H. Lemmetyinen and N. V
Tkachenko, ChemPhysChem, 2010, 11, 1685–1692.
X. K. Liu, Z. Chen, C. J. Zheng, C. L. Liu, C. S. Lee, F. Li, X. M.
Ou and X. H. Zhang, Adv. Mater., 2015, 27, 2378–2383.
Z. Chi, X. Zhang, B. Xu, X. Zhou, C. Ma, Y. Zhang, S. Liu and J.
Xu, Chem. Soc. Rev., 2012, 41, 3878–3896.
Y. Gong, Y. Zhang, W. Z. Yuan, J. Z. Sun and Y. Zhang, J.
Phys. Chem. C, 2014, 118, 10998–11005.
This journal is © The Royal Society of Chemistry 2018
J. Name., 2018, 00, 1-3 | 4
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 5 of 5
View Article Online
DOI: 10.1039/C8OB00272J
Organic & Biomolecular Chemistry
COMMUNICATION
20
21
J. T. Hynes, Rev. Port. Quim., 1995, 2, 12–17.
1356–1364.
Q. Zhang, B. Li, S. Huang, H. Nomura, H. Tanaka and C. 38
Adachi, Nat. Photonics, 2014, 8, 326–332.
V. F. T. A. Y. Bochkov, I. O. Akchurin, O. A. Dyachenko,
Chem. Commun., 2013, 11653–11655.
22
23
H. Kaji, H. Suzuki, T. Fukushima, K. Shizu, K. Suzuki, S. Kubo, 39
T. Komino, H. Oiwa, F. Suzuki, A. Wakamiya, Y. Murata and
A. Martin, C. Long, R. J. Forster and T. E. Keyes, Chem.
Commun., 2012, 48, 5617-5619.
C. Adachi, Nat. Commun., 2015, 6, 8476 (1-8).
40
M. Bröring, R. Krüger, S. Link, C. Kleeberg, S. Köhler, X. Xie,
B. Ventura and L. Flamigni, Chem. Eur. J., 2008, 14, 2976–
2983.
S. Hirata, Y. Sakai, K. Masui, H. Tanaka, S. Y. Lee, H.
Nomura, N. Nakamura, M. Yasumatsu, H. Nakanotani, Q.
Zhang, K. Shizu, H. Miyazaki and C. Adachi, Nat. Mater., 41
2014, 14, 330–336.
R. Ghosh and D. K. Palit, J. Phys. Chem. A, 2015, 119,
11128–11137.
24
N. B. Teran, G. S. He, A. Baev, Y. Shi, M. T. Swihart, P. N. 42
Prasad, T. J. Marks and J. R. Reynolds, J. Am. Chem. Soc.,
2016, 138, 6975–6984.
J. C. Blakesley, F. A. Castro, W. Kylberg, G. F. A. Dibb, C.
Arantes, R. Valaski, M. Cremona, J. S. Kim and J. S. Kim,
Org. Electron., 2014, 15, 1263–1272.
25
26
27
28
W. Zhang, Y.-Y. Ren, L.-N. Zhang, X. Fan, H. Fan, Y. Wu, Y. 43
Zhang and G.-C. Kuang, RSC Adv., 2016, 6, 101937–101940.
M.-E. Ragoussi and T. Torres, Chem. Commun., 2015, 51,
3957–3972.
J. Zhou, X. Wan, Y. Liu, Y. Zuo, Z. Li, G. He, G. Long, W. Ni, C.
Li, X. Su and Y. Chen, J. Am. Chem. Soc., 2012, 134, 16345–
16351.
J. Hou, M.-H. Park, S. Zhang, Y. Yao, L.-M. Chen, J.-H. Li and
Y. Yang, Macromolecules, 2008, 41, 6012–6018.
T. Qin, W. Zajaczkowski, W. Pisula, M. Baumgarten, M.
Chen, M. Gao, G. Wilson, C. D. Easton, K. Müllen and S. E.
Watkins, J. Am. Chem. Soc., 2014, 136, 6049–6055.
Y. Huang, X. Guo, F. Liu, L. Huo, Y. Chen, T. P. Russell, C. C.
Han, Y. Li and J. Hou, Adv. Mater., 2012, 24, 3383–3389.
S. Sengupta, U. K. Pandey and E. U. Athresh, RSC Adv.,
2016, 6, 73645–73649.
29
30
31
32
W. G. Santos, J. Pina, H. D. Burrows, M. Forbes and D. R.
Cardoso, Photochem. Photobiol. Sci., 2016, 15, 1124–1137.
D. Collado, J. Casado, S. R. González, J. T. L. Navarrete, R.
Suau, E. Perez-Inestrosa, T. M. Pappenfus and M. M. M.
Raposo, Chem. Eur. J., 2011, 17, 498–507.
33
34
Y. Liang, D. Feng, Y. Wu, S.-T. Tsai, G. Li, C. Ray and L. Yu, J.
Am. Chem. Soc., 2009, 131, 7792–7799.
A. J. F. N. Sobral, N. G. C. L. Rebanda, M. da Silva, S. H.
Lampreia, M. Ramos Silva, A. M. Beja, J. . Paixão and A. M.
D. A. Rocha Gonsalves, Tetrahedron Lett., 2003, 44, 3971–
3973.
35
36
A. K. Rawat and S. M. S. Chauhan, Der Pharma Chem.,
2014, 6, 316–322.
R. C. 0. Gaussian 09, G. E. S. M. J. Frisch, G. W. Trucks, H. B.
Schlegel, B. M. M. A. Robb, J. R. Cheeseman, G. Scalmani,
V. Barone, H. P. H. G. A. Petersson, H. Nakatsuji, M.
Caricato, X. Li, M. H. A. F. Izmaylov, J. Bloino, G. Zheng, J. L.
Sonnenberg, T. N. M. Ehara, K. Toyota, R. Fukuda, J.
Hasegawa, M. Ishida, J. Y. Honda, O. Kitao, H. Nakai, T.
Vreven, J. A. Montgomery, E. B. J. E. Peralta, F. Ogliaro, M.
Bearpark, J. J. Heyd, J. N. K. N. Kudin, V. N. Staroverov, T.
Keith, R. Kobayashi, J. T. K. Raghavachari, A. Rendell, J. C.
Burant, S. S. Iyengar, J. B. C. M. Cossi, N. Rega, J. M. Millam,
M. Klene, J. E. Knox, R. E. S. V. Bakken, C. Adamo, J.
Jaramillo, R. Gomperts, J. W. O. O. Yazyev, A. J. Austin, R.
Cammi, C. Pomelli, G. A. V. R. L. Martin, K. Morokuma, V. G.
Zakrzewski, A. D. D. P. Salvador, J. J. Dannenberg, S.
Dapprich, J. C. O. Farkas, J. B. Foresman, J. V. Ortiz and
2010. and D. J. Fox, Gaussian, Inc., Wallingford CT, 2010.
G. Chen, H. Sasabe, Y. Sasaki, H. Katagiri, X.-F. Wang, T.
Sano, Z. Hong, Y. Yang and J. Kido, Chem. Mater., 2014, 26,
37
This journal is © The Royal Society of Chemistry 2018
J. Name., 2018, 00, 1-3 | 5
Please do not adjust margins