(Deep) blue through-space conjugated TADF emitters based on [2.2]paracyclophanes

Article abstract of DOI:10.1039/c8cc04594a

The first examples of through-space conjugated thermally activated delayed fluorescence (TADF) emitters based on a [2.2]paracyclophane (PCP) skeleton with stacked (coplanar) donor-acceptor groups have been synthesized. The optoelectronic properties are studied by the relative configuration, cis (pseudo-geminal) and trans (pseudo-para), of the donor and acceptor groups.

Full text of DOI:10.1039/c8cc04594a

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: E. Spuling, N.
Sharma, I. Samuel, E. Zysman-Colman and S. Braese, Chem. Commun., 2018, DOI:
1
0.1039/C8CC04594A.
Volume 52 Number
1
4
January 2016 Pages 1–216
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
ChemComm
Chemical Communications
www.rsc.org/chemcomm
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 1359-7345
COMMUNICATION
Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc
first methanofullerene derivatives of Sc
3
N@C2n (2n
=
68 and 80). Synthesis of the
3
N@D5h-C80
rsc.li/chemcomm

Page 1 of 48
ChemComm
Chemical Communications
View Article Online
Guidelines for referees
DOI: 10.1039/C8CC04594A
ChemComm is a forum for urgent high quality communications from
across the chemical sciences.
Communications in ChemComm should be preliminary accounts of
original and urgent work of significance to a general chemistry
audience. The 2016 impact factor for ChemComm is 6.319.
Only work within the top 25% of the field in terms of quality and
interest should be recommended for publication. Acceptance should
only be recommended if the content is of such urgency and
significant general interest that rapid publication will be
advantageous to the progress of chemical research.
Routine and incremental work – however competently researched and reported –
should not be recommended for publication.
Articles which rely excessively on supplementary information should not be
recommended for publication.
Thank you very much for your assistance in evaluating this manuscript.
General Guidance
Referees have the responsibility to treat the manuscript as confidential. Please be aware of our
Ethical Guidelines, which contain full information on the responsibilities of referees and authors,
and our Refereeing Procedure and Policy.
Supporting information and characterisation of new compounds
Experimental information must be provided to enable other researchers to reproduce the work
accurately. It is the responsibility of authors to provide fully convincing evidence for the
homogeneity, purity and identity of all compounds they claim as new. This evidence is required to
establish that the properties and constants reported are those of the compound with the new
structure claimed.
Please assess the evidence presented in support of the claims made by the authors and comment
on whether adequate supporting information has been provided to address the above. Further
details on the requirements for characterisation criteria can be found here.
When preparing your report, please:
•
•
comment on the originality, significance, impact and scientific reliability of the work;
state clearly whether you would like to see the article accepted or rejected and give detailed
comments (with references, as appropriate) that will both help the Editor to make a decision on
the article and the authors to improve it;
•
it is the expectation that only work with two strong endorsements will be accepted for publication.
Please inform the Editor if:
•
•
•
•
•
there is a conflict of interest;
there is a significant part of the work which you are not able to referee with confidence;
the work, or a significant part of the work, has previously been published;
you believe the work, or a significant part of the work, is currently submitted elsewhere;
the work represents part of an unduly fragmented investigation.
Submit your report at http://mc.manuscriptcentral.com/chemcomm

ChemComm
Page 2 of 48
View Article Online
DOI: 10.1039/C8CC04594A
ELI ZYSMAN-COLMAN, Ph.D., FRSC
School of Chemistry, University of St Andrews,
Purdie Building, North Haugh
KY16 9ST
eli.zysman-colman@st-andrews.ac.uk
Tel.: +44-1334 463826; Fax.: +44-1334 463808
http://www.zysman-colman.com
0
1/07/2018
Dear Referees,
We are delighted to hear of the positive assessment of our manuscript. We hope that with these responses
and modifications to the manuscript that it now is now in a state to accepted for publication. Below is a
point-by-point description of the changes made to the manuscript in response to the points brought up by
the referees.
REVIEWER
Referee:
REPORT(S):
1
1
. The photoluminescence quantum efficiencies of 3 and 7 in the PMMA and mCP doped film were much
lower than those in toluene solutions. In typical cases of TADF emitters, doped films show higher
quantum efficiencies than solution state because the molecular motions can be effectively suppressed in
the solid phases. The observations in this paper seem to be an opposite. The reviewer expects another
intermolecular exciton-quenching process might be occur in the condensed states. The authors should
calculate the rate constants for radiative and nonradiative decays, ISC, and RISC for 3 and 7, compare the
values between the solution and doped films, and also expand the discussion on this point. This will be of
highly importance to further enhance the photoluminescence properties in the solid thin films.
Many thanks to the referee for highlighting this point.
To address this issue, we considered different possibilities that could cause a decrease in PLQY in the
solid-state.
1
2
. We considered if aggregation caused quenching is responsible for this behaviour. We measured
the PLQY of the mCP thin films at 1 and 3 wt.% doping concentration of 3 and 7. We observed
a further decrease in the PLQY at low doping concentration. Increasing the doping
concentration beyond 15 wt.% also resulted in a decrease in PLQY (see Table S1).
. We next examined different host matrices to evaluate the effect of environment and polarity on
the PLQY. Regardless of the host used, PLQY remained low, with mCP providing the highest
PLQY, regardless of doping concentrations (Table S1).
3
4
. We note that the PLQYs are low and not significantly different for both isomers. Therefore,
intramolecular interactions leading to a non-radiative pathway can be ruled out.
. We analyzed the time-resolved PL spectra of 3 and 7 in PhMe more closely, and the lack of a
delayed component in the time-resolved PL spectra in solution would argue that the compounds
are not or are only weakly TADF in solution.
Tel: +44 1334 463826; Fax: +44 1334 463808; eli.zysman-colman@st-andrews.ac.uk; http://www.zysman-colman.com

Page 3 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
We therefore have a situation where the compounds are only TADF in the thin film state. The
additional nr decay can due to intersystem crossing to the triplet and this loss channel also explains the
apparently lower radiative rate decay constant in thin film due to the differrence in mechanism of the
radiative decay (TADF vs fluorescence).
We have calculated the rate constants and added the data to Table S2, page S22. We have assumed that
the non-radiative decay rate from S1 is 0 (see justification on page S22). The radiative decay rates in
solution are an order of magnitude larger than in the film. This is a function of the different emission
mechanisms in the two environments: fluorescence versus TADF.
2
. Related to the comment 1, in the solid state, not only intramolecular exciplex but also intermolecular
species can be involved in the TADF process. So, the authors should measure and compare the
photophysical properties for the mixture of corresponding benzophenone and triphenylamine derivative
(
without cyclophane linker) particularly in the doped films. Are there any differences between the mix
system and the present cyclophane-linked system?
We have considered intermolecular interactions (excimer or exciplex between donor and acceptors) by
investigating the photophysical behaviour at low doping concentrations. We measured the PLQYs of 3
and 7 at both 1-3 wt.% concentrations in different host matrices (Table S1). We observed a further
small decrease in PLQY upon decreasing the doping concentration, regardless of host matrix. These
new measurements would suggest that no intermolecular interactions are involved in the TADF process
of 3 and 7 or contribute to the decreased PLQY.
3
. Have the authors try to fabricate doped films with much lower concentration of 3 and 7? The reviewer
expects higher PL quantum efficiencies in such low-concentration doped film.
We have followed the referee’s helpful suggestion. We measured the PLQYs of 3 and 7 at much lower
doping concentrations (1-3 wt.%) in different host matrices (Table S1). Please see our responses to
points 1 and 2.
4
. The authors have prepared doped films via vacuum deposition. The prototype OLEDs can thus be
constructed by using the same protocol. The authors should provide the data for OLEDs in the revised
manuscript. This is very informative for those working in this field.
The key point of the manuscript is the paradigm shift in design of TADF emitters with the use of
paracyclophane as a bridge. These are a new class of materials where coupling between donor and
acceptor is mediated through the PCP core. However, PLQYs of both the isomers remained low in their
vacuum-deposited films. Therefore, isomers 3 and 7 are not suitable candidates for OLED fabrication.
Indeed, with a careful modification in the design, PLQY of such type of emitters can be improved. This
is discussed at the end of the paper where we write “We are presently investigating modified designs to
mitigate this issue such that paracyclophane-based TADF emitters can be incorporated into OLED
devices.”
Referee:
2
1
. Upon changing the donor group to the weaker carbazole unit, relatively large ΔESTs were obtained for
isomers 4 and 8 in theoretical simulation. It is strongly recommended that the authors carry out more
experimental studies to verify the accuracy of DFT calculation.
Tel: +44 1334 463826; Fax: +44 1334 463808; eli.zysman-colman@st-andrews.ac.uk; http://www.zysman-colman.com

ChemComm
Page 4 of 48
View Article Online
DOI: 10.1039/C8CC04594A
We wish to note that we have used a well-established DFT/TDA protocol to calculate the ground and
excited state properties of these compounds (J. Chem. Theory Comput. 2015, 11, 168; Phy. Rev.
Materials., 2017, 1, 075602). Not unexpectedly,
predicted S energy increases. In PhMe we observed a blue-shifted emission at ca. 380 nm for both 4
and 8, which was very very weak. This meant that we could not measure ST. Given the UV nature of
the emission, the effective very low PLQY of the emission and the large calculated ST we opted to
D
EST increases with decreasing donor strength and the
1
D
E
D
E
concentrate our photophysical analyses on promising isomers 3 and 7 exclusively and discounted
isomers 4 and 8 as emissive materials for TADF.
2
. The authors presented two isomeric TADF emitters with cis- or trans-structure. However, the authors
provided limited comparison of their optoelectronic properties. It is strongly recommended that the
authors provide more discussion on the relationship between molecular structures and optoelectronic
properties of these two emitters.
We have added the following text to the manuscript (page 3)
“
The optoelectronic properties of 3 and 7 are influenced by the relative configuration of D and A. A
red-shift in the emission spectra was observed for the cis isomer 3 across all media compared to 7. This
behaviour implies that the electronic coupling between D and A is stronger in the cis configuration
than that in the trans configuration, likely a function of secondary p-p interactions in the former.”
3
. Page 2, right column, the authors claimed that the high intensity absorption band at 311 nm was
assigned to the ICT transition from D to A through the PCP. Generally, the ICT absorption band is usually
pretty weak in common TADF molecules. This strong absorption band at 311 nm could be a LE transition
from D and/or A. it is strongly commended that the authors provided more data to support this claim.
To support our claim, we examined the nature and character of transitions around 311 nm with the
help of TD-DFT data. We found that the transition at 311 nm has contributions from H -> L, H ->L+2
and H -> L+5, where H is the HOMO and L is the LUMO of the molecule. In both isomers, transitions
from H -> L and H ->L+2 have the major contribution of 76% and are charge transfer in nature. The
transition from H -> L+5 has a minor contribution of 4%, which is of LE character localized on the
donor moiety. Thus, based on these observations, we assigned the strong absorption band at 311 nm to
the ICT transition from D to A through PCP. We have added the natural transition orbital diagrams of
L+2 and L+ 5 to ESI (figure S4). We have added the following text in the main manuscript (page 2)
“
Both isomers possess a high intensity absorption band at 311 nm, which was assigned to the ICT
transition from D to A through the PCP based on TD-DFT calculations (Figure S4).”.
4
. Page 3, right column, the experimental ΔEST was underestimated when S1 was calculated by room
temperature fluorescence spectra, while T1 was estimated from 77 K phosphorescence spectra. It is
strongly recommended that the authors recalculated the ΔEST values of these new compounds.
We have recalculated the ΔEST for both the isomers from the onset of prompt and delayed spectra
measured at 77K in 15 wt.% doped films in mCP. ΔEST values of 0.13 eV and 0.17 eV were observed for
3
and 7 respectively. We have updated the figure 4 and the corresponding text in the main manuscript.
The text now reads “The ΔEST of 3 and 7 were determined from the singlet and triplet energies
estimated from the onset of the prompt and delayed emission spectra, respectively, measured in 15 wt%
mCP doped films at 77 K (Fig 4). Both isomers exhibited high singlet energies coupled with small ΔEST
values of 0.13 eV and 0.17 eV for 3 and 7, respectively, confirming their TADF character.”
Tel: +44 1334 463826; Fax: +44 1334 463808; eli.zysman-colman@st-andrews.ac.uk; http://www.zysman-colman.com

Page 5 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
5
. If possible, the authors could employ these two TADF emitters in OLED to check how the devices
work.
Please see our response to point 4 of referee 1
6
. Page 3, right column, the caption of Figure 5 and the main text should be separated.
We have separated the caption of Figure 5 (page 3) from the main text.
. Page 3, right column, for the transient PL part, it is strongly recommended that the authors provide
7
fitting curves and parameters for the transient PL curves of both emitters.
We have added the Updated figures and fitting parameters to ESI (Figure S2, page S21).
8
.
Typo:
Page 3, left column, wt% should be wt.%.
We have replaced wt% with wt.% throughout the manuscript.
Sincerely,
Eli Zysman-Colman
Tel: +44 1334 463826; Fax: +44 1334 463808; eli.zysman-colman@st-andrews.ac.uk; http://www.zysman-colman.com

Please d Co hn eomt Ca do jmu smt margins
Page 6 of 48
View Article Online
DOI: 10.1039/C8CC04594A
Journal Name
COMMUNICATION
(
[
Deep) Blue Through-Space Conjugated TADF Emitters Based on
2.2]Paracyclophanes
Received 00th January 20xx,
Accepted 00th January 20xx
a
b,c
c
b
Eduard Spuling,‡ Nidhi Sharma,‡ Ifor D. W. Samuel, * Eli Zysman-Colman, * and Stefan
Bräse *
a,d
DOI: 10.1039/x0xx00000x
www.rsc.org/
The first examples of through-space conjugated thermally exchange integral, recent findings indicate that planar
activated delayed fluorescence (TADF) emitters based on a structures can exhibit TADF as well while maintaining a strong
8
, 9
[2.2]paracyclophane (PCP) skeleton with stacked (coplanar) oscillator strength.
These examples demonstrate that the
donor-acceptor groups have been synthesized. The optoelectronic mechanism of and design rules governing TADF are still ripe for
1
0
properties are studied by the relative configuration, cis (pseudo- continuing investigation. Another striking design concept for
geminal) and trans (pseudo-para), of the donor and acceptor TADF that has been explored by Swager, Baldo et al. is the
groups.
electronic communication of donor and acceptor groups
mediated by through-space conjugation either using
triptycene skeleton confining the donor and acceptor units in a
a
Thermally activated delayed fluorescence (TADF) is now
regarded as the most promising mechanism for harvesting
1
excitons in electroluminescent devices and has thus garnered
1
1
1
20° orientation, or a xanthene-linked cofacial disposition of
1
donor (D) and acceptor (A) with a distance of 3.3–3.5 Å.
2
much attention in organic light-emitting diode (OLED) research
Although TADF was observed with delayed lifetimes,
between 2.0–3.0 µs and moderate
through-space electronic communication mainly occurred via
τ
D
2
following the seminal works of Adachi et al. A small energy
-5
Φ
PL in this latter report, the
gap (ΔE ) between the singlet and triplet excited states
ST
.
..
permits rapid effective equilibration between the two via
intersystem crossing (ISC) and reverse intersystem crossing
C–H π interactions, creating efficient aggregation induced
emission.
(
rISC), evidenced by an observed thermally promoted delayed
1
The [2.2]paracyclophane (PCP) is a compact skeleton confining
two benzene rings (“decks”) by ethylene bridges in a coplanar,
though slightly bent and configurationally stable, conformation
, 6
fluorescence upon photo- or electrical excitation.
A small
ΔEST is achieved through a small exchange integral between
frontier molecular orbitals; however, this has the potential to
compromise the photoluminescence quantum yield (ΦPL) by
reducing the oscillator strength of the transition. Therefore,
strict design principles must be followed to produce bright and
1
3
with a deck distance of 3.09 Å, which is smaller than the van
der Waals distance between layers of graphite (3.35 Å). This
enables a stronger transannular electronic communication
between the benzene decks. This model compound for π–π
transannular interaction sparked numerous investigations over
the last decades. For instance, Bazan et al. investigated D–A
stilbene derivatives based on PCP that exhibited nonlinear
optical properties and significant through-space charge
7
efficient TADF emitters. Although the vast majority of
reported TADF emitters adhere to the design paradigm of
molecules containing donors and acceptors possessing a highly
twisted relative conformation in order to minimize the
1
4, 15
transfer,
including strong positive solvatochromism caused
1
by a polarizable electronic structure in the excited state.
6
Morisaki, Chujo et al. focused on PCP-based through-space π-
extended conjugated polymers, demonstrating that electronic
interactions can be effective through more than ten layers in
the ground state, yet emission in these systems occurs from
the isolated monomer π systems, giving access to well-defined
monomer-localized HOMO-LUMO gaps rather than a broad
1
7,
18
valence-conduction band gap in the polymers.
Additionally, given the inherent planar chirality in PCPs, this
scaffold can yield chromophores with intense circular polarized
1
9-22
luminescence.
Despite these fascinating properties, PCP
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 7 of 48
View Article Online
DOI: 10.1039/C8CC04594A
COMMUNICATION
Journal Name
chemistry suffers from challenging or sometimes In order to obtain both the cis and trans isomers (pseudo-
unpredictable reactivity. Although various successful cross- geminal and pseudo-para in PCP terminology, see Figure S1),
2
3
coupling protocols have been reported, a direct C-N coupling two different approaches were investigated (Scheme 1).
to a N-heterocycle such as carbazole (Cz) or diphenylamine Compound was synthesized by Friedel-Craft acylation of PCP
2
2
4, 25
(DPA), though claimed in numerous patents,
has never and subsequent exploitation of the transannular directing
been reported in the scientific literature thus far.
effect to selectively target the pseudo-geminal position of the
2
In this communication we report the first examples of carbonyl group towards electrophilic aromatic bromination.
6
thermally activated delayed fluorescence enabled by through- The trans (pseudo-para) intermediate
6
was obtained by
of the highly insoluble pseudo-para
followed by quenching with benzoyl chloride. The
1
4
space conjugation of a [2.2]paracyclophane skeleton (Fig. 1).
monolithiation
dibromide
intermediates
5
2
7-29
2
and 6 possess benzoyl acceptor groups
Donor
Donor
and a bromo-functionalized building block suitable for cross-
coupling of various donor groups. Targeting deep blue
emitters, relatively weak donors (4’-N,N-diphenylamino)phenyl
and (4’-N-carbazolyl)phenyl were installed via optimized
Suzuki-Miyaura protocols (ESI) in moderate to good yields.
T
A
D
F
3.09 Å
T
A
D
F
Acceptor
Acceptor
trans (pseudo-para)
cis (pseudo-geminal)
Figure 1 Concept of through-space conjugation of a [2.2]paracyclophane skeleton for
thermally activated delayed fluorescence (TADF).
Scheme 1 [2.2]paracyclophane (PCP) based through-space conjugated benzoyl acceptor TADF systems. Left: Synthesis of pseudo-geminal (cis) TADF systems. Right: Synthesis of
pseudo-para (trans) TADF systems. All molecules were prepared in a racemic fashion.
Density functional theory (DFT) calculations were performed in for isomer
the gas phase to assess the electronic structures of both cis photoluminescence (PL) spectra of
and trans derivatives (see ESI for details). The S and T excited data are summarized in Table . Both isomers possess a high
states were calculated from the optimized ground state intensity absorption band at 311 nm, which was assigned to
4
and
8. Figure 3a shows the UV-Vis absorption and
3
and in toluene and the
7
1
1
1
3
0, 31
structure using the Tamm-Dancoff approximations
to TD-DFT. Focusing on the DPA derivatives, Fig. , the highest DFT calculations (Fig. S4).
occupied molecular orbitals (HOMO) and lowest unoccupied
molecular orbitals (LUMO) for and are mainly localized
(TDA) the ICT transition from D to A through the PCP based on TD-
2
3
7
over the donor and acceptor moieties and the adjoining
benzene deck, respectively. The strong transannular electronic
communication mediated by the PCP core promotes an
efficient through space intramolecular charge transfer (ICT)
while the inherent rigidity of the PCP was expected to
minimize the vibrational motion of the molecule thereby
reducing non-radiative decay pathways. The well separated
frontier orbitals resulted in small calculated ΔEST values of
0.04 eV and 0.19 eV for
3
and
7, respectively, coupled with
high excited singlet energies (S
1
state), suggesting their strong
potential as deep blue TADF emitters. Upon changing the
donor group to the weaker carbazole, relatively large ΔEST
Figure 2. HOMO-LUMO profiles and excited state dynamics of cis and trans isomers 3
and 7, respectively (pbe0/6-31G(d,p)).
values of 0.32 eV and 0.46 eV for isomers
4 and 8, respectively,
were observed (Fig. S2). No further studies were carried out
2
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please d Co hn eomt Ca do jmu smt margins
Page 8 of 48
View Article Online
DOI: 10.1039/C8CC04594A
Journal Name
COMMUNICATION
In the PL spectra in PhMe, both isomers exhibited two distinct
bands. The high energy band centred at 410 nm and 404 nm
for
formed between two benzene decks of PCP scaffold.
low energy band at 492 nm for and 455 nm for
3 and 7, respectively, was assigned to the “phane state”
3
2, 33
The
was
3
7
attributed to the ICT transition between donor and acceptor
moieties. Photoluminescence quantum yields, PL, in PhMe for
and were 45% and 60%, which decreased to 30% and 42%,
respectively, upon exposure to air. Time-resolved PL spectra
Fig. S1), however, do not show a delayed emission lifetime
Φ
3
7
(
component, which would suggest that the TADF mechanism in
solution is either not present or very weak.
We next investigated the solid-state PL behaviour of both
derivatives in doped thin films (Fig. 3b). In the thin film, both singlet energies coupled with small ΔEST values of 0.13 eV and
derivatives exhibited an unstructured emission profile, 0.17 eV for and , respectively, confirming their TADF
characteristic of an excited state with significant ICT character. character
3
7
.
Figure
4. Prompt and delayed (by 50
ꢀ
s, 200
ꢀs window) spectra of 3 and 7 in 15
wt.% mCP doped films, measured at 77 K. (
λ
exc = 378 nm)
Transient PL measurements in 15 wt.% mCP doped films
revealed biexponential decay kinetics. Both isomers exhibited
a prompt lifetime,
very short delayed lifetime,
). Furthermore, rates of reverse intersystem crossing, krISC
τ
P
, of 17 ns (for
3
) and 7.4 ns (for
7
) and a
D
τ , of 1.8
ꢀ
s (for ) and 3.6
3
ꢀ
s (for
7
Figure 3. a.) UV-Vis and PL spectra in degassed PhMe and b.) PL spectra in 10 wt.%
doped films in PMMA and 15 wt.% doped films in mCP of 3 (black) and 7 (red). λexc
60 nm.
5
-1
5
-1
were found to 7.0 × 10 s and 3.1 × 10 s for
respectively (Table S2, ESI). Such short and large krISC values
are characteristics of an efficient rISC mechanism. Despite the
showed desirable blue emission and short delayed lifetimes, the
PL of 485 nm while the emission of
these emitters remained poor. We investigated a range of
was slightly blue-shifted at 470 nm in strong agreement with high-energy host materials, such as DPEPO and CzSi, and
the calculated S
energies. Both isomers exhibited a prompt doping concentrations (from 1-25 wt.%) in an effort to
lifetime, P, of 19 ns (for ) and 10 ns (for
), followed by a very enhance the PL in the solid state; however, the highest
of 0.7 s and 1.6 s for and
values were found in mCP at 15 wt.% (Table S1).
PL of the PMMA films of both the
and 7.5% for . With a
3 and 7,
=
τ
D
3
In 10 wt.% doped solution-processed films in PMMA,
sky-blue emission with
3
ΦPL of
λ
7
1
τ
3
7
Φ
Φ
PL
short delayed component,
τ
D
ꢀ
ꢀ
3
7,
respectively. However, the
Φ
isomers remained low, close to 5% for
3
7
view to employing these compounds as emitters in OLEDs, we
next studied the emitters in the high triplet energy host, 1,3-
bis(N-carbazolyl)benzene, mCP, with a vacuum-deposited
doping concentration of 15 wt.%. The emission maxima were
a.
b.
slightly blue-shifted at 480 and 465 nm for
3 and 7,
respectively, with strongly reduced ΦPL of 12 and 15%,
respectively, compared to solution-state measurements.
Reducing the doping concentration to 1 wt.% resulted in
reduced
optoelectronic properties of
relative configuration of D and A. A red-shift in the emission
spectra was observed for the cis isomer across all media
compared to . This behaviour implies that the electronic
Φ
PL of 7% for both isomers (Table S1). The
Figure
exc
5. Temperature dependence of delayed lifetime of a.) 3 and b.) 7. λ =
3
and are influenced by the
7
3
78 nm.
3
To further corroborate the TADF nature of these emitters, we
investigated the temperature dependence of the delayed
7
coupling between D and A is stronger in the cis configuration
than that in the trans configuration, likely a function of
lifetimes (Fig. 5). For both compounds, the intensity of delayed
emission gradually increases with increasing temperature,
providing direct evidence of TADF.
secondary
π
-π
interactions in the former.
and were determined from the singlet and
The ΔEST of
3
7
triplet energies estimated from the onset of the prompt and Table 1. Photophysical properties of 3 and 7.
delayed emission spectra, respectively, measured in 15 wt.%
mCP doped films at 77 K (Fig 4). Both isomers exhibited high
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 9 of 48
View Article Online
DOI: 10.1039/C8CC04594A
COMMUNICATION
Journal Name
a
a
b
c
d
d
5
6
7
8
.
.
.
.
Q. Zhang, J. Li, K. Shizu, S. Huang, S. Hirata, H. Miyazaki and C.
Adachi, J. Am. Chem. Soc., 2012, 134, 14706-14709.
Z. Yang, Z. Mao, Z. Xie, Y. Zhang, S. Liu, J. Zhao, J. Xu, Z. Chi and
M. P. Aldred, Chem. Soc. Rev., 2017, 46, 915-1016.
Y. Im, M. Kim, Y. J. Cho, J. A. Seo, K. S. Yook and J. Y. Lee, Chem.
Mater., 2017, 29, 1946-1963.
λabs
λPL
ΦPL
ΦPL
τP
τD
/
nm
/ nm
/ %
/ %
/ ns
/ ꢀs
3
(cis)
311
312
480
45
(
12
17 (0.88) 1.8
(0.12)
30)
T. Hatakeyama, K. Shiren, K. Nakajima, S. Nomura, S. Nakatsuka,
K. Kinoshita, J. Ni, Y. Ono and T. Ikuta, Adv. Mater., 2016, 28,
7
(trans)
465
60
(
15
7.4 (0.44) 3.6
(0.56)
2
777-2781.
42)
9
1
1
.
X. K. Chen, Y. Tsuchiya, Y. Ishikawa, C. Zhong, C. Adachi and J. L.
Bredas, Adv. Mater., 2017, 29, 1702767.
a
b
In degassed PhMe at 298 K. 0.5 M quinine sulfate in H
2
SO
4
(aq) was used as the
0. T. J. Penfold, F. B. Dias and A. P. Monkman, Chem. Commun.,
018, 54, 3926-3935.
1. K. Kawasumi, T. Wu, T. Zhu, H. S. Chae, T. Van Voorhis, M. A.
34
reference (ΦPL: 54.6%, λexc : 360 nm). Values quoted are in degassed solutions,
which were prepared by three freeze-pump-thaw cycles. Values in parentheses are
2
c
for aerated solutions, which were prepared by bubbling air for 10 min. Thin films
were prepared by vacuum depositing 15 wt.% doped samples in mCP and values
Baldo and T. M. Swager, J. Am. Chem. Soc., 2015, 137, 11908-
1
1911.
were determined using an integrating sphere (λexc : 360 nm); degassing was done by
d
N
2
purge.
Values in parentheses are the pre-exponential weighting factors,
12. H. Tsujimoto, D. G. Ha, G. Markopoulos, H. S. Chae, M. A. Baldo
determined in 15 wt.% mCP doped films of 3 and 7 ( λexc : 378 nm).
and T. M. Swager, J. Am. Chem. Soc., 2017, 139, 4894-4900.
1
1
3. D. J. Cram and J. M. Cram, Acc. Chem. Res., 1971, 4, 204-213.
4. J. Zyss, I. Ledoux, S. Volkov, V. Chernyak, S. Mukamel, G. P.
Bartholomew and G. C. Bazan, J. Am. Chem. Soc., 2000, 122,
1
1956-11962.
5. G. P. Bartholomew and G. C. Bazan, Acc. Chem. Res., 2001, 34,
0-39.
6. J. W. Hong, H. Y. Woo, B. Liu and G. C. Bazan, J. Am. Chem. Soc.,
005, 127, 7435-7443.
In conclusion, we have developed the first examples of TADF
emitters incorporating a PCP core, which we exploited to
mediate electronic communication between donor and
acceptor groups on adjoining benzene decks. Both the cis and
trans isomers exhibited blue TADF emission and short delayed
1
1
3
2
1
1
1
7. Y. Morisaki and Y. Chujo, Polym. Chem., 2011, 2, 1249-1257.
8. Y. Morisaki and Y. Chujo, Chem. Lett., 2012, 41, 840-846.
9. Y. Morisaki, M. Gon, T. Sasamori, N. Tokitoh and Y. Chujo, J. Am.
Chem. Soc., 2014, 136, 3350-3353.
lifetimes in the range of 1–3 ꢀs. These compounds
unfortunately possess low photoluminescence quantum yields
in the solid state. We are presently investigating modified
designs to mitigate this issue such that paracyclophane-based 20. M. Gon, Y. Morisaki, R. Sawada and Y. Chujo, Chemistry, 2016,
22, 2291-2298.
TADF emitters can be incorporated into OLED devices.
2
2
2
2
1. M. Gon, Y. Morisaki and Y. Chujo, Chem. Commun., 2017, 53,
8
304-8307.
2. M. Gon, R. Sawada, Y. Morisaki and Y. Chujo, Macromolecules,
017, 50, 1790-1802.
Conflicts of interest
2
There are no conflicts to declare.
3. C. Braun, E. Spuling, N. B. Heine, M. Cakici, M. Nieger and S.
Bräse, Adv. Synth. Catal., 2016, 358, 1664-1670.
4. K.-J. Yoon, H.-J. Noh, D.-W. Yoon, I.-A. Shin and J.-Y. Kim
EP3029753B1.
Acknowledgements
2
2
2
5. S. L. Buchwald and W. Huang US20160359118A1.
6. H. J. Reich and D. J. Cram, J. Am. Chem. Soc., 1968, 90, 1365-&.
7. S. Y. Lee, T. Yasuda, Y. S. Yang, Q. Zhang and C. Adachi, Angew.
Chem. Int. Ed. Engl., 2014, 53, 6402-6406.
8. P. Rajamalli, D. R. Martir and E. Zysman-Colman, ACS Appl.
Energy Mater., 2018, 1, 649-654.
E. S. and S. B. acknowledge funding from DFG in the frame of
SFB1176 (projects A4, B3 and C6) and KSOP (fellowship to E.
S.). E. Z.-C. and I. D. W. S. thank the Engineering and Physical
Sciences Research Council (EPSRC) (No. EP/P010482/1) for
financial support. I.D.W.S. also acknowledges support from a
2
Royal Society Wolfson Research Merit Award. We thank the 29. R. P. Gounder, D. R. Martir and E. Zysman-Colman, J. Photon.
Energy, 2018, 8, 032106.
EPSRC UK National Mass Spectrometry Facility at Swansea
University for analytical services.
3
0. J. P. Perdew, M. Emzerhof and K. Burke, J. Chem. Phys., 1996,
1
05, 9982-9985.
3
3
1. S. Grimme, Chem. Phys. Lett., 1996, 259, 128-137.
2. E. Elacqua and L. R. MacGillivray, Eur. J. Org. Chem., 2010, 2010,
Notes and references
6
883-6894.
1.
2.
3.
4.
M. Y. Wong and E. Zysman-Colman, Adv. Mater., 2017, 29,
605444.
A. Endo, M. Ogasawara, A. Takahashi, D. Yokoyama, Y. Kato and
C. Adachi, Adv. Mater., 2009, 21, 4802-4806.
A. Endo, K. Sato, K. Yoshimura, T. Kai, A. Kawada, H. Miyazaki
and C. Adachi, Appl. Phys. Lett., 2011, 98, 42.
H. Uoyama, K. Goushi, K. Shizu, H. Nomura and C. Adachi,
Nature, 2012, 492, 234-238.
33. J. L. Zafra, A. Molina Ontoria, P. Mayorga Burrezo, M. Pena-
Alvarez, M. Samoc, J. Szeremeta, F. J. Ramirez, M. D. Lovander,
C. J. Droske, T. M. Pappenfus, L. Echegoyen, J. T. Lopez
Navarrete, N. Martin and J. Casado, J. Am. Chem. Soc., 2017,
139, 3095-3105.
1
34. W. H. Melhuish, J. Phys. Chem., 1961, 65, 229-235.
4
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

ChemComm
Page 10 of 48
View Article Online
DOI: 10.1039/C8CC04594A
Electronic Supporting Information (ESI)
(
Deep) Blue Through-Space Conjugated TADF Emitters
Based on [2.2]Paracyclophanes
a
b,c
c
b
a,d
Eduard Spuling,‡ Nidhi Sharma,‡ Ifor D. W. Samuel, * Eli Zysman-Colman, * and Stefan Bräse *
a
Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131
Karlsruhe, Germany. Fax: (+49)-721-6084-8581; phone: (+49)-721-6084-2903; E-mail: braese@kit.edu
b
Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews,
Fife, KY16 9ST, UK. E-mail: eli.zysman-colman@st-andrews.ac.uk ; Web: http://www.zysman-colman.com;
Fax:+44 (0)1334 463808; Tel:+44 (0)1334 463826
c
Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North
Haugh, St Andrews, KY16 9SS, U.K. E-mail: idws@st-andrews.ac.uk
d
Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-
Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
Table of Contents
Additional Information ........................................................................................................................................... 2ꢀ
2
.ꢀ Synthesis of Compounds ................................................................................................................................ 3ꢀ
2
2
.1.ꢀ General Remarks..................................................................................................................................... 3ꢀ
.2.ꢀ Synthetic Procedures and Analytical Data.............................................................................................. 4ꢀ
3
4
5
.ꢀ Photophysical Characterization .................................................................................................................... 20ꢀ
.ꢀ DFT modelling.............................................................................................................................................. 23ꢀ
.ꢀ References..................................................................................................................................................... 38ꢀ
S1

Page 11 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
Additional Information
Nomenclature of [2.2]Paracyclophanes
1
The IUPAC nomenclature for cyclophanes in general is confusing. Therefore Vögtle et al. developed a specific
2
cyclophane nomenclature, which is based on a core-substituent ranking. This is exemplified in Figure S1 for the
[2.2]paracyclophane.
Figure S1. Entire nomenclature shown on both 4-formyl[2.2]paracyclophane enantiomers.
The core structure is named according to the length of the aliphatic bridges in squared brackets (e.g. [n.m]) and
the benzene substitution patterns (ortho, meta or para). [2.2]Paracyclophane belongs to the D2h symmetry, which
is broken by the first substituent, resulting in two planar chiral enantiomers. They cannot be drawn in a racemic
fashion. By definition, the arene bearing the substituent is set to a chirality plane, and the first atom of the
cyclophane structure outside the plane and closest to the chirality center is defined as the “pilot atom”. If both
arenes are substituted, the substituent with higher priority according to the Cahn-Ingold-Prelog (CIP)
3
nomenclature is preferred. The stereo descriptor is determined by the sense of rotation viewed from the pilot
atom. To describe the positions of the substituents correctly, an unambiguous numeration is needed. The
numbering of the arenes follows the sense of rotation determined by CIP. To indicate the planarity of the chiral
center, a subscripted p is added. Unfortunately the numbering of the second arene is not consistent in the literature.
Therefore another description based on the benzene substitution patterns is preferred for disubstituted
[2.2]paracyclophanes. Substitution on the other ring is commonly named pseudo-(ortho, meta, para or geminal).
With respect to the scope and aim of this communication pseudo-para (4,16) derivatives are named “trans” and
pseudo-geminal (4,13) derivatives “cis”.
S2

ChemComm
Page 12 of 48
View Article Online
DOI: 10.1039/C8CC04594A
2
2
. Synthesis of Compounds
.1. General Remarks
NMR spectra were recorded on a Bruker AM 400 or a Bruker Avance 500 spectrometer as solutions at room
temperature. Chemical shifts d are expressed in parts per million (ppm) downfield from tetramethylsilane (TMS).
1
13
1
References for H NMR and C NMR were the residual solvent peaks of chloroform ( H: d = 7.26 ppm), DMSO
1
13
13
(
H: d = 2.50 ppm), D
constants (J) are absolute values and are expressed in Hertz (Hz). The description of signals includes: s = singlet,
d = doublet, t = triplet, q = quartet, quin = quintet, m = multiplet, m = centered multiplet, dd = doublet of doublets
and ddd = double doublet of doublets and so forth. The spectra were analyzed according to first order. The
1 6
-chloroform ( C: d = 77.0 ppm) and D -DMSO ( C: d = 39.43 ppm). All coupling
c
1
13
assignments of the signal structure in H NMR were made by the multiplicity and for C NMR by DEPT 90- and
DEPT 135-spectra (DEPT = distortionless enhancement by polarization transfer) and are described as follows: +
=
primary or tertiary C-atom (positive DEPT-signal), – = secondary C-atom (negative signal) and
quart. = quaternary C-atom (no signal).
C
IR spectra were recorded on a FT-IR Bruker IFS 88 spectrometer. The compounds were measured as pure
substances by ATR technique (ATR = attenuated total reflection). The position of the absorption band is given in
-
1
wave numbers ṽ in cm . The intensities of the bands were characterized as follows: vs = very strong (0–20% T),
s = strong (21–40% T), m = medium (41–60% T), w = weak (61–80% T), vw = very weak (81–100% T).
Melting points were measured using a Cambridge Instruments device, model OptiMelt MPA 100 with a
o
temperature increase of 1 C/min.
Mass spectra were measured by EI-MS (electron impact mass spectrometry) and were recorded on a Finnigan
+
MAT 95. The peaks are given as mass-to-charge-ratio (m/z). The molecule peak is given as [M] and characteristic
+
+
fragment peaks are given as [M-fragment] or [fragment] . The signal intensities are given in percent, relatively
to the intensity of the base signal (100%). For the high resolution mass, the following abbreviations were used:
calc. = calculated data, found = measured data.
Analytical thin layer chromatography (TLC) was carried out on Merck silica gel coated aluminum plates (silica
gel 60, F254), detected under UV-light at 254 nm or stained with “Seebach staining solution” (mixture of
molybdato phosphoric acid, cerium(IV)-sulfate tetrahydrate, sulfuric acid and water) or basic potassium
permanganate solution. Solvent mixtures are understood as volume/volume. Solvents, reagents and chemicals
were purchased from Sigma-Aldrich, ABCR and Acros Organics. All solvents, reagents and chemicals were used
as purchased unless stated otherwise.
Air- or moisture-sensitive reactions were carried out under argon atmosphere in oven-dried and previously
evacuated glass ware. Liquids were transferred with plastic syringes and steel cannula. Reaction control was
S3

Page 13 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
performed by thin layer chromatography. If not stated otherwise, crude products were purified by flash
4
chromatography by the procedure of Still. Silica gel 60 (0.040 × 0.063 mm, Geduran®, Merck) was used as
stationary phase and as mobile phase, solvents of p.a. quality were used.
2
.2. Synthetic Procedures and Analytical Data
4
,16-dibromo[2.2]paracyclophane (5):
The synthesis followed a modified protocol reported in literature. To iron powder (241 mg,
5
4
.32 mmol, 4.50 mol%) were added 15 mL of a solution of 10.3 mL bromine (32.1 g, 201 mmol,
.10 equiv.) in 80 mL dichloromethane. After stirring for 1 h, the reaction mixture was diluted
2
with 100 mL dichloromethane and [2.2]paracyclophane (20.0 g, 96.0 mmol, 1.00 equiv.) were
added. The mixture was stirred for further 30 min, followed by dropwise addition of the residual bromine solution
over 5 h. The reaction mixture was stirred for 3 d. Then a sat. aqueous solution of Na SO was added to the
2
3
reaction mixture, which was stirred until decoloration occurred (1 h). The organic phase was filtrated and the
residual solid dried without further purification. The product was obtained in 9.52 g (26.0 mmol, 28%) as a white
solid.
1
R
f
= 0.72 (CH/EA 10:1). - H NMR (400 MHz, CDCl
3
): d = 7.14 (dd, J = 7.8, 1.8 Hz, 2H), 6.51 (d, J = 1.7 Hz,
2
2
H), 6.44 (d, J = 7.8 Hz, 2H), 3.49 (ddd, J = 13.0, J = 10.4, 2.3 Hz, 2H), 3.15 (ddd, J = 12.7, 10.4, 4.9 Hz, 2H),
1
3
3
.94 (ddd, J = 12.7, 10.7, 2.3 Hz, 2H), 2.85 (ddd, J = 13.2, 10.7, 5.0 Hz, 2H) ppm. - CꢀNMR (100 MHz, CDCl ):
d = 141.3 (Cquart.), 138.7 (Cquart.), 137.5 (+), 134.2 (+), 128.4 (+), 126.9 (Cquart.), 35.5 (-), 33.0 (-) ppm. - IR
(ATR): ῦ = 2931 (vw), 2849 (vw), 1582 (vw), 1535 (vw), 1473 (vw). 1449 (vw), 1432 (vw), 1390 (w), 1185 (vw),
-
1
1
3
3
030(w), 898 (w), 855 (w), 829 (w), 706 (w), 669 (w), 648 (w), 464 (w) cm . - MS (70 eV, EI), m/z (%):
+
+
+
79
68/366/364 (19/38/20) [M] , 184/182 (100/95) [M- C
8
H
7
Br] , 103 (19) [C
8
H
7
] . - HRMS (C16
H
2
14 Br ) calc.:
6
63.9457; found: 363.9457. Analytical data matches that of the literature.
S4

ChemComm
Page 14 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S5

Page 15 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
(rac, “trans”) 4 -bromo-16-benzoyl[2.2]paracyclophane (6):
n
A solution of BuLi (3.94 mL of 2.5 M in hexane, 9.84 mmol, 1.20 equiv.) was added
dropwise to a solution of 4,16-dibromo[2.2]paracyclophane (5) (3.00 g, 8.20 mmol, 1.00
equiv.) in 150 mL dry tetrahydrofuran at -78 °C under argon atmosphere. After stirring for
1
h, the reaction mixture was warmed up to 0 °C and 7.56 mL of benzoyl chloride (9.22 g,
6
5.6 mmol, 8.00 equiv.) were added quickly. The reaction mixture was warmed up to room temperature and
stirred for 16 h. The reaction mixture was quenched by addition of water and was extracted with ethyl acetate (3
100 mL). The combined organic phases were washed with sat. aqueous NH Cl solution (100 mL), brine
×
4
(
100 mL), dried over Na SO and the solvent was removed under reduced pressure. The crude product was
2 4
purified by column chromatography (silica gel, cyclohexane/ethyl acetate; 50/1) to yield 4.24 g of an off-white
solid (5.58 mmol, 68%).
1
R
f
= 0.22 (CH/EA 50:1). - H NMR (400 MHz, CDCl ) δ = 7.70 (d, J = 7.8 Hz, 2H), 7.55 (t, J = 7.4 Hz, 1H),
3
7
6
3
.41 (t, J = 7.4 Hz, 2H), 7.35 (dd, J = 7.8, 1.9 Hz, 1H), 6.78 (dd, J = 7.9, 1.8 Hz, 1H), 6.68 (d, J = 1.9 Hz, 1H),
.60 (d, J = 1.8 Hz, 1H), 6.56 (d, J = 7.8 Hz, 1H), 6.33 (d, J = 7.8 Hz, 1H), 3.46 (ddd, J = 13.2, 10.4, 2.7 Hz, 1H),
1
3
.35 (ddd, J = 12.5, 10.5, 2.1 Hz, 1H), 3.28 – 3.19 (m, 2H), 3.01 – 2.93 (m, 2H), 2.92 – 2.76 (m, 2H) ppm. – C
NMR (101 MHz, CDCl ) δ = 196.78 (Cquat., CO), 141.99 (Cquat.), 141.19 (Cquat.), 139.02 (Cquat.), 138.75 (Cquat.),
3
1
1
1
8
38.64 (Cquat.), 137.09 (+), 136.85 (Cquat.), 134.84 (+), 134.61 (+), 134.48 (+), 132.69 (+), 132.23(+), 130.16 (+),
30.06 (+), 128.38 (+), 126.54 (Cquat.), 35.11 (–), 34.87 (–), 34.85 (–), 33.27 (–) ppm. – IR (ATR): ῦ = 2926 (vw),
645 (w), 1587 (vw), 1478 (vw), 1448 (vw), 1392 (vw), 1313 (vw), 1279 (w), 1033 (vw), 989 (vw), 908 (vw),
89 (vw), 855 (vw), 822 (w), 742 (w), 722 (vw), 701 (m), 667 (w), 652 (w), 639 (w), 514 (vw), 476 (w), 458
-
1
79
81
+
79
81
+
(
vw), 397 (vw) cm – MS (FAB, 3-NBA), m/z: 391/393 [M( Br/ Br)+H] , 390/392 [M( Br/ Br)] . - HRMS
7
9
79
(C
23
H
19 BrO) calc.: 390.0619; found: 390.0620. – HRMS (C23H19 BrO+H) calc.: 391.0698; found: 391.0700.
S6

ChemComm
Page 16 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S7

Page 17 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
(rac, “trans”) 4-Benzoyl-16-(4’-N-carbazolyl)phenyl[2.2]paracyclophane (8):
In a pressure vial were charged (rac)-4-bromo-16-benzoyl[2.2]paracyclophane
(
(
6) (97.8 mg, 250 µmol, 1.00 equiv.), 4-(N-carbazolyl)phenyl boronic acid
144 mg, 500 µmol, 2.00 equiv.), Cs CO (244 mg, 750 µmol, 3.00 equiv.), and
2
3
Pd(PPh ) Cl (21.1 mg, 30.0 µmol, 10 mol%). The sealed vial was evacuated and
3
2
2
flushed with argon three times. Through the septum 6 mL of degassed
tetrahydrofuran and 1.5 mL of degassed water were added, then heated to 75 °C and stirred for 16 h. The reaction
mixture was diluted in 50 mL of ethyl acetate and washed first with sat. aqueous NH Cl solution (3 × 30 mL) and
4
then with brine (30 mL). The organic layer was dried over Na SO and the solvent was removed under reduced
2
4
pressure. The crude product was purified by column chromatography (silica gel, cyclohexane/ethyl acetate; 50/1)
to yield 106 mg of the product as a white solid (191 µmol, 76%).
1
R = 0.14 (CH/EA 50:1). – H NMR (400 MHz, CDCl ) δ = 8.09 (d, J = 7.8 Hz, 2H), 7.70 – 7.64 (m, 2H), 7.60
f
3
(s, 4H), 7.49 – 7.45 (m, 3H), 7.41 – 7.31 (m, 4H), 7.25 – 7.21 (m, 2H), 6.77 – 6.69 (m, 3H), 6.67 (d, J = 1.9 Hz,
1
2
H), 6.59 (d, J = 8.3 Hz, 1H), 6.42 (d, J = 7.8 Hz, 1H), 3.44 – 3.18 (m, 3H), 3.06 – 2.97 (m, 2H), 2.96 – 2.83 (m,
1
3
H), 2.76 (ddd, J = 14.3, 10.2, 5.2 Hz, 1H) ppm. – C NMR (101 MHz, CDCl ) δ = 196.90 (Cquat., CO), 141.57
3
(Cquat.), 141.29 (Cquat.), 140.96 (Cquat.), 140.55 (Cquat.), 140.35 (Cquat.), 139.60 (Cquat.), 138.81 (Cquat.), 136.90 (Cquat.),
1
1
36.75 (Cquat.), 136.60 (Cquat.), 135.51 (+), 134.81 (+), 134.59 (+), 133.22 (+), 132.74 (+), 131.98 (+), 131.22 (+),
30.97 (+), 130.18 (+), 128.42 (+), 127.16 (+), 126.11(+), 123.59 (Cquat.), 120.51 (+), 120.16 (+), 110.04 (+), 35.42
o
(
–), 35.20 (–), 35.02 (–), 33.28 (–) ppm. – Mp : 145-150 C. - IR (ATR): ῦ = 3045 (vw), 2922 (vw), 2852 (vw),
1
1
651 (w), 1596 (vw), 1514 (w), 1478 (vw), 1449 (w), 1335 (vw), 1315 (vw), 1269 (w), 1228 (w), 1171 (vw),
-
1
026 (vw), 913 (vw), 838 (vw), 748 (w), 723 (w), 701 (w), 656 (vw), 565 (vw), 489 (vw), 423 (vw) cm . – MS
+
+
(
FAB, 3-NBA), m/z: 554 [M+H] , 553 [M] . - HRMS (C41H31NO) calc.: 553.2406; found: 553.2403.
S8

ChemComm
Page 18 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S9

Page 19 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
(rac, “trans”) 4-Benzoyl-16-(4’-N-diphenylamino)phenyl[2.2]paracyclophane (7):
In a pressure vial were charged (rac)-4-bromo-16-benzoyl[2.2]paracyclophane
(6) (97.8 mg, 250 µmol, 1.00 equiv.), 4-(N-diphenylamino)phenyl boronic acid
(
144 mg, 500 µmol, 2.00 equiv.), Cs CO (244 mg, 750 µmol, 3.00 equiv.), and
2
3
Pd(PPh ) Cl (21.1 mg, 30.0 µmol, 10 mol%). The sealed vial was evacuated and
3
2
2
flushed with argon three times. Through the septum 6 mL of degassed
tetrahydrofuran and 1.5 mL of degassed water were added, then heated to 75 °C and stirred for 16 h. The reaction
mixture was diluted in 50 mL of ethyl acetate and washed first with sat. aqueous NH Cl solution (3 × 30 mL) and
4
then with brine (30 mL). The organic layer was dried over Na SO and the solvent was removed under reduced
2
4
pressure. The crude product was purified by column chromatography (silica gel, cyclohexane/ethyl acetate; 50/1)
to yield 92.2 mg of the product as an off-white solid (65%, 166 µmol).
1
R = 0.14 (CH/EA 50:1). – H NMR (400 MHz, CDCl ) δ = 7.79 – 7.69 (m, 2H), 7.59 – 7.51 (m, 1H), 7.42 (t, J =
f
3
7
7
3
.7 Hz, 2H), 7.35 – 7.27 (m, 6H), 7.21 – 7.14 (m, 6H), 7.10 – 7.02 (m, 2H), 6.81 – 6.75 (m, 2H), 6.71 (dd, J =
.8, 1.9 Hz, 1H), 6.64 (d, J = 1.9 Hz, 1H), 6.57 (d, J = 7.5 Hz, 1H), 6.43 (d, J = 7.8 Hz, 1H), 3.44 – 3.34 (m, 2H),
1
3
.34 – 3.24 (m, 1H), 3.11 – 2.86 (m, 4H), 2.85 – 2.74 (m, 1H) ppm. – C NMR (101 MHz, CDCl ) δ = 196.88
3
(
Cquat., CO), 147.84 (Cquat.), 146.79 (Cquat.), 141.79 (Cquat.), 141.52 (Cquat.), 140.00 (Cquat.), 139.63 (Cquat.), 138.90
Cquat.), 136.68 (Cquat.), 136.64 (Cquat.), 135.50 (Cquat.), 135.28 (+), 134.75 (+), 134.53 (+), 133.25 (+), 132.64 (+),
(
1
31.73 (+), 130.56 (+), 130.28 (+), 130.14 (+), 129.52 (+), 129.45 (+), 128.37 (+), 124.96 (+), 124.73 (+), 123.41
o
(
+), 123.13 (+), 35.38 (–), 35.18 (–), 34.89 (–), 33.36 (–) ppm. – Mp : 125-130 C. - IR (ATR): ῦ = 3058 (vw),
3
1
3
032 (vw), 2923 (w), 2853 (vw), 2258 (vw), 1715 (vw), 1652 (w), 1589 (w), 1487 (w), 1447 (vw), 1270 (m),
-
1
151 (w), 1110 (w), 1024 (m), 819 (w), 753 (w), 695 (m), 617 (w), 510 (w), 483 (w), 426 (vw) cm . – MS (FAB,
+
+
-NBA), m/z: 556 [M+H] , 555 [M] . - HRMS (C41
H
33NO) calc.: 555.2562; found: 555.2564.
S10

ChemComm
Page 20 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S11

Page 21 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
(rac)-4-Benzoyl[2.2]paracyclophane (1)
In a 250 mL flask, [2.2]paracyclophane (10.4 g, 50.0 mmol, 1.00 equiv.) was dissolved in
1
00 mL of dichloromethane and cooled to –10 °C. A solution of benzoyl chloride (11.5 mL,
1
4.1 g, 100 mmol, 2.00 equiv.) and AlCl (11.7 g, 88.0 mmol, 1.75 equiv.) in 50 mL of
3
dichloromethane were added and stirred for 1 h. The reaction mixture was filtered through
glass wool and hydrolyzed with ice. Extraction was carried out with dichloromethane (200 mL), afterwards the
organic layer was washed with aqueous NaHCO (200 mL) solution and brine (200 mL), then dried over Na SO .
3
2
4
The solvent was evaporated under reduced pressure and the residue was recrystallized in ethanol to yield 12.4 g
(39.7 mmol, 79%) of colorless crystals.
1
R = 0.53 (CH/EA 40:1) – H NMR (400 MHz, CDCl ) δ = 7.72 (d, J = 7.8 Hz, 2H), 7.56 – 7.53 (m, 1H), 7.42 (t,
f
3
J = 7.7 Hz, 2H), 6.77 (d, J = 7.9 Hz, 1H), 6.71 – 6.69 (m, 2H), 6.58 – 6.55 (m, 3H), 6.35 (d, J = 7.9 Hz, 1H), 3.39
1
3
–
1
3.09 (m, 5H), 3.07 – 2.84 (m, 3H) ppm. – C NMR (101 MHz, CDCl ) δ = 196.68 (Cquat., CO), 141.68 (Cquat.),
3
39.96 (Cquat.) 139.37 (Cquat.), 138.95 (Cquat.), 136.42 (Cquat.), 136.14 (+), 135.77 (+), 134.36 (+), 132.82 (+), 132.76
(
+), 132.52 (+), 132.45 (+), 131.22 (+), 130.04 (+), 128.31 (+), 35.67 (–), 35.36 (–), 35.30 (–), 35.17 (–) ppm. –
IR (ATR) ṽ = 2919 (w), 2848 (vw), 1649 (m), 1594 (w), 1446 (w), 1411 (vw), 1318 (w), 1294 (w), 1269 (w),
1
4
196 (w), 976 (w), 941 (w), 907 (w), 891 (w), 835 (w), 803 (w), 726 (w), 700 (m), 656 (w), 634 (m), 509 (m),
-
1
+
+
+
54 (vw) cm . – MS (EI, 70 eV) m/z [%] = 313 (25) [M+H] , 312 (100) [M] , 208 (86) [M–C H ] , 207 (73) [M–
8
8
+
+
+
C H ] , 105 (11) [C H ] , 104 (29) [C H ] . – HRMS (C H O) calc. 312.1509; found 312.1510. The analytical
8
9
8
9
8
8
23 20
7
data matches that of the literature.
S12

ChemComm
Page 22 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S13

Page 23 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
(rac, “cis”)-4-Bromo-13-benzoyl[2.2]paracyclophane (2)
A solution of 2.51 mL bromine (7.82 g, 49.0 mmol, 1.02 equiv.,) in 60 mL of
dichloromethane was prepared in a dropping funnel and 5 mL of this solution were added
to iron filings (50.0 mg, 960 µmol, 2 mol%) in a 500 mL three neck flask and stirred for 1 h
at room temperature. Then 100 mL of dichloromethane and (rac)-4-
benzoyl[2.2]paracyclophane (1) (15.0 g, 48.0 mmol, 1.00 equiv.) were added and stirred for
another 30 min. The remainder of the bromine solution was added dropwise over a period of 5 h and the mixture
was stirred for 3 days. The reaction was quenched with a saturated sodium sulfite solution (200 mL) and stirred
for 30 min until full discoloration of the mixture. The organic phase was separated, washed with brine (200 mL)
and dried over Na SO . The filtrate was evaporated and the residue was purified by flash chromatography (silica,
2
4
4
0:1 cyclohexane:ethyl acetate) to yield 8.60 g (21.9 mmol, 46%) of a white solid.
1
R = 0.23 (CH/EA 40:1) – H NMR (500 MHz, CDCl ) δ = 7.73 (d, J = 7.7 Hz, 2H), 7.53 (t, J = 7.4 Hz, 1H), 7.42
f
3
(t, J = 7.6 Hz, 2H), 7.28 (d, J = 1.9 Hz, 1H), 6.74 (dd, J = 7.7, 1.9 Hz, 1H), 6.68 – 6.53 (m, 4H), 3.44 (ddd, J =
1
2.8, 9.6, 2.3 Hz, 1H), 3.29 (ddd, J = 13.2, 9.6, 5.7 Hz, 1H), 3.18 – 3.04 (m, 3H), 3.02 – 2.94 (m, 1H), 2.88 (ddd,
1
3
J = 12.9, 10.0, 2.3 Hz, 1H), 2.79 (ddd, J = 13.2, 10.0, 5.7 Hz, 1H) ppm – C NMR (126 MHz, CDCl ) δ = 195.38
3
(Cquat., CO), 142.33 (Cquat.), 141.39 (Cquat.), 140.63 (Cquat.), 138.89 (Cquat.), 136.94 (+), 136.21 (+), 135.90 (Cquat.),
1
35.61 (+), 134.95 (+), 133.90 (+), 131.81 (+), 130.93 (+), 129.78 (+), 128.26 (+), 127.30 (Cquat.), 36.36 (–), 35.12
(
(
(
(
(
–), 34.64 (–), 33.88 (–) ppm. – IR (ATR) ṽ = 2927 (w), 1742 (w), 1649 (m), 1587 (w), 1471 (w), 1445 (w), 1388
w), 1268 (m), 1240 (w), 1205 (w), 1030 (w), 981 (w), 951 (w), 890 (w), 836 (w), 800 (w), 735 (m), 700 (m), 652
-
1
81
+
w), 637 (w), 604 (w), 519 (w), 479 (w), 390 (vw) cm . – MS (EI, 70 eV) m/z [%] = 393 (12) [M( Br)+H] , 392
8
1
+
79
+
79
+
+
+
50) [M( Br)] , 391 (12) [M( Br)+H] , 390 (47) [M( Br)] , 208 (100) [M–C H Br] , 207 (91) [M–C H Br] , 106
8
7
8
8
+
79
39) [CHOPh] . – HRMS (C H BrO) calc. 390.0614; found 390.0612.
2
3
19
S14

ChemComm
Page 24 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S15

Page 25 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
(rac, “cis”) 4-Benzoyl-13-(4’-N-carbazolyl)phenyl[2.2]paracyclophane (4):
In a pressure vial were charged with (rac)-4-bromo-13-benzoyl[2.2]paracyclophane (2)
156.5 mg, 400 µmol, 1.00 equiv.), 4-(N-carbazolyl)phenyl boronic acid (229 mg,
(
8
4
00 µmol. 2.00 equiv.), K PO (170 mg, 800 µmol, 2.00 equiv.), Pd(OAc) (8.98 mg,
3 4 2
0.0 µmol, 10 mol%) and 2-dicyclohexylphosphino-2,6-diisopropoxybiphenyl
(“RuPhos”) (37.3 mg, 80.0 µmol, 20 mol%). The sealed vial was evacuated and flushed
with argon three times. Through the septum 7 mL of degassed toluene and 1 mL of degassed water were added,
then heated to 75 °C and stirred for 16 h. The reaction mixture was diluted in 50 mL of ethyl acetate and washed
first with sat. aqueous NH Cl solution (3 × 30 mL) and then with brine (30 mL). The organic layer was dried over
4
Na SO and the solvent was removed under reduced pressure. The crude product was purified by column
2
4
chromatography (silica gel, cyclohexane/ethyl acetate; 20/1) to yield 126 mg of the product as a white solid
227 µmol, 57%).
(
1
R = 0.34 (CH/EA 20:1). – H NMR (400 MHz, CDCl ) δ = 8.20 (d, J = 7.8 Hz, 2H), 7.64 – 7.40 (m, 11H), 7.33
f
3
(
td, J = 7.4, 4.9 Hz, 4H), 7.08 (d, J = 2.0 Hz, 1H), 6.92 (dd, J = 7.8, 1.9 Hz, 1H), 6.85 (d, J = 8.1 Hz, 1H), 6.80
d, J = 7.7 Hz, 1H), 6.66 (d, J = 2.1 Hz, 2H), 3.88 (ddd, J = 13.4, 9.3, 6.4 Hz, 1H), 3.40 (ddd, J = 12.3, 9.2, 2.5
(
1
3
Hz, 1H), 3.35 – 3.14 (m, 3H), 3.14 – 2.95 (m, 2H), 2.87 (ddd, J = 13.0, 9.2, 6.3 Hz, 1H) ppm. – C NMR (101
MHz, CDCl ) δ = 194.73 (C CO), 143.89 (Cquat.), 141.42 (Cquat.), 141.28 (Cquat.), 140.07 (Cquat.), 139.80 (Cquat.),
3
quat.,
1
39.29 (Cquat.), 138.96 (Cquat.), 137.90 (Cquat.), 136.58 (+), 136.23 (Cquat.), 136.17 (+), 135.92 (+), 134.95 (+), 134.04
(Cquat.), 132.59 (+), 131.88 (+), 131.42 (+), 130.78 (+), 130.15 (+), 128.12 (+), 127.02 (+), 126.11 (+), 123.49
o
(
Cquat.), 120.44 (+), 119.99 (+), 110.15 (+), 37.25 (–), 35.22 (–), 35.15 (–), 34.31 (–) ppm. – Mp : 165-175 C. –
IR (ATR): ῦ = 2922 (vw), 1733 (vw), 1650 (vw), 1595 (vw), 1515 (vw), 1477 (vw), 1450 (w), 1334 (vw), 1315
(vw), 1269 (vw), 1230 (w), 978 (vw), 914 (vw), 837 (vw), 749 (vw), 723 (w), 700 (w), 632 (vw), 566 (vw), 525
-
1
+
+
(
vw), 487 (vw), 424 (vw) cm – MS (FAB, 3-NBA), m/z: 554 [M+H] , 553 [M] . - HRMS (C41
H31NO) calc.:
5
53.2406; found: 553.2405.
S16

ChemComm
Page 26 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S17

Page 27 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
(rac, “cis”) 4-Benzoyl-13-(4’-N-diphenylamino)phenyl[2.2]paracyclophane (3):
In a pressure vial were charged with (rac)-4-bromo-13-benzoyl[2.2]paracyclophane (2)
156.5 mg, 400 µmol, 1.00 equiv.), 4-(N-diphenylamino)phenyl boronic acid (231 mg,
(
8
00 µmol. 2.00 equiv.), K PO (170 mg, 800 µmol, 2.00 equiv.), Pd(OAc) (4.50 mg,
3 4 2
2
0.0 µmol,
5
mol%) and 2-dicyclohexylphosphino-2,6-diisopropoxybiphenyl
(“RuPhos”) (18.7 mg, 40.0 µmol, 10 mol%). The sealed vial was evacuated and flushed
with argon three times. Through the septum 7 mL of degassed toluene and 1 mL of degassed water were added,
then heated to 75 °C and stirred for 16 h. The reaction mixture was diluted in 50 mL of ethyl acetate and washed
first with sat. aqueous NH Cl solution (3 × 30 mL) and then with brine (30 mL). The organic layer was dried over
4
Na SO and the solvent was removed under reduced pressure. The crude product was purified by column
2
4
chromatography (silica gel, gradient of cyclohexane/ethyl acetate; 50/1 to 20/1) to yield 145 mg of the product as
an off-white solid (261 µmol, 65%).
1
R =0.26 (CH/EA 20:1) = 0.26. – H NMR (400 MHz, CDCl ) δ = 7.44 (t, J = 7.3 Hz, 1H), 7.36 – 7.29 (m, 5H),
f
3
7
1
3
.28 – 7.20 (m, 7H), 7.16 – 7.02 (m, 6H), 6.96 (d, J = 1.9 Hz, 1H), 6.87 (dd, J = 7.7, 1.8 Hz, 1H), 6.76 (dd, J =
1.6, 7.7 Hz, 2H), 6.57 (dd, J = 7.6, 1.9 Hz, 1H), 6.51 (d, J = 1.9 Hz, 1H), 3.82 (ddd, J = 13.3, 9.2, 6.6 Hz, 1H),
.47 – 3.35 (m, 1H), 3.33 – 3.22 (m, 1H), 3.20 – 3.08 (m, 2H), 3.07 – 2.89 (m, 2H), 2.87 – 2.73 (m, 1H) ppm. –
C NMR (101 MHz, CDCl ) δ = 194.72 (C CO), 148.10 (Cquat.), 146.61 (Cquat.), 144.20 (Cquat.), 141.98 (Cquat.),
1
3
3
quat.,
1
1
1
39.98 (Cquat.), 139.00 (Cquat.), 138.79 (Cquat.), 137.75 (Cquat.), 136.46 (+), 136.10 (+), 135.63 (+), 135.44 (Cquat.),
35.20 (+), 133.74 (Cquat.), 131.92 (+), 131.60 (+), 130.81 (+), 130.39 (+), 130.29 (+), 129.41 (+), 127.92 (+),
o
24.45 (+), 124.03 (+), 122.80 (+), 37.32 (–), 35.23 (–), 35.15 (–), 34.19 (–) ppm. – Mp : 91-95 C. – IR (ATR):
ῦ = 2922 (vw), 1736 (w), 1649 (w), 1588 (w), 1509 (w), 1486 (w), 1445 (w), 1316 (w), 1268 (m), 1175 (w), 1074
(vw), 1046 (vw), 977 (vw), 916 (vw), 834 (w), 800 (vw), 751 (w), 696 (m), 661 (w), 648 (w), 634 (w), 550 (vw),
-
1
+
+
5
12 (w), 489 (vw) cm . – MS (FAB, 3-NBA), m/z: 556 [M+H] , 555 [M] . - HRMS (C41H33NO) calc.: 555.2562;
found: 555.2561.
S18

ChemComm
Page 28 of 48
View Article Online
DOI: 10.1039/C8CC04594A
S19

Page 29 of 48
ChemComm
View Article Online
DOI: 10.1039/C8CC04594A
3
. Photophysical Characterization
-
5
-6
Photophysical measurements. Optically dilute solutions of concentrations in the order of 10 or 10 M were
prepared in HPLC grade solvent for absorption and emission analysis. Absorption spectra were recorded at
room temperature on a Shimadzu UV-1800 double beam spectrophotometer. Aerated solutions were
bubbled with compressed air for 5 minutes whereas degassed solutions were prepared via three freeze-pump-
thaw cycles prior to emission analysis using an in-house adapted fluorescence cuvette, itself purchased from
Starna. Steady-state emission and time-resolved emission spectra were recorded at 298 K using an
Edinburgh Instruments F980 fluorimeter. Samples were excited at 360 nm for steady-state measurements
and at 378 nm for time-resolved measurements. Photoluminescence quantum yields for solutions were
8
determined using the optically dilute method in which four sample solutions with absorbance at 360 nm
being ca. 0.10, 0.080, 0.060 and 0.040 were used. Their emission intensities were compared with those of a
r 2 4
reference, quinine sulfate, whose quantum yield (Φ ) in 1 N H SO was determined to be 54.6% using
9
absolute method. The quantum yield of sample, ΦPL, can be determined by the equation ΦPL
=
2
Φ
r
(A
r
/A
s
)((I
s
/I
r
)(n
s
/n
r
) , where A stands for the absorbance at the excitation wavelength (λexc: 360 nm), I is
the integrated area under the corrected emission curve and n is the refractive index of the solvent with the
subscripts “s” and “r” representing sample and reference respectively. An integrating sphere was employed
for quantum yield measurements for thin film samples.
Figure S1. Transient PL decay profiles of a.) 3 and b.) 7 in degassed PhMe (λexc = 378 nm).
S20