Synthesis of Molecular Dyads and Triads Based Upon N-Annulated Perylene Diimide Monomers and Dimers

Article abstract of DOI:10.1002/ejoc.201801383

The synthesis of N-annulated perylene diimides (NPDIs) with grafted electron donating phenothiazine (PTZ) groups is presented. The synthetic strategy takes advantage of the N-annulation at the PDI bay position, which allows for the facile installation of the pendant donors. Three new molecular materials are reported, a dyad consisting of an NPDI monomer tethered to a PZT unit (4), a dyad consisting of an NPDI dimer with one PZT unit tethered (9), and a triad consisting of an NPDI dimer with two PTZ units tethered (10). The PTZ and NPDI were “clicked” together using copper catalyzed alkyne–azide cycloaddition chemistry. Analysis of optical absorption/emission spectra and electrochemical data reveal that the electronic structure of each individual aromatic system remains distinct, but through-space interactions occur, as is evident by fluorescence quenching in both solution and the solid state.

Full text of DOI:10.1002/ejoc.201801383

A Journal of
Accepted Article
Title: Synthesis of Molecular Dyads and Triads based upon N-
Annulated Perylene Diimide Monomers and Dimers
Authors: Jonathan R. Cann, Clement Cabanetos, and Gregory Charles
Welch
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of the final Version of Record (VoR). This work is currently citable by
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the VoR from the journal website shown below when it is published
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content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201801383
Link to VoR: http://dx.doi.org/10.1002/ejoc.201801383
Supported by

10.1002/ejoc.201801383
European Journal of Organic Chemistry
Synthesis of Molecular Dyads and Triads based upon N-Annulated Perylene Diimide Monomers
and Dimers
Mr. Jonathan R. Cann,1 Dr. Clement Cabanetos,2 Prof. Gregory C. Welch1*
1Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N
1N4, Canada.
2CNRS UMR 6200, MOLTECH-Anjou, University of Angers, 2 Bd Lavoisier, Angers, France, 49045
*E-mail: gregory.welch@ucalgary.ca
*Webpage: http://welchlab.wixsite.com/website
KEYWORDS: Organic Dyes, Perylene Diimide, N-Annulation, Phenothiazine, Molecular Dyads and
Triads
ABSTRACT: The synthesis of N-annulated perylene diimides (NPDIs) with grafted electron donating
phenothiazine (PTZ) groups is presented. The synthetic strategy takes advantage of the N-annulation at
the PDI bay position which allows for the facile installation of the pendant donors. Three new molecular
materials are reported, a dyad consisting of an NPDI monomer tethered to a PZT unit (4), a dyad consisting
of an NPDI dimer with one PZT unit tethered (9), and a triad consisting of an NPDI dimer with two PTZ
units tethered (10). The PTZ and NPDI were ‘clicked’ together using copper catalyzed alkyne-azide
cycloaddition chemistry. Analysis of optical absorption/emission spectra and electrochemical data reveal
that the electronic structure of each individual aromatic system remains distinct, but through-space
interactions occurs as evident by fluorescence quenching in both solution and the solid-state.
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1. Introduction
Organic molecular and polymeric dyads and triads are systems where two or more distinct
π-conjugated systems are present in the same material. Such dyads and triads have been explored
for many applications ranging from fundamental energy[1] or charge transfer studies[2,3] to
functional applications like fluorescence sensing,[4] ambipolar organic field effect transistors[5,6]
and single component organic photovoltaics.[7–11] Dyad systems are built having well-defined
electron donor and acceptor components, which have an energetic offset in their frontier molecular
orbitals enabling charge transfer, energy transfer, or both hole and electron transport. These
systems can be designed either with metal-ligand complexes, which are especially effective for
photocatalytic transformations,[12] or with organic π-conjugated systems which have found a wide
variety of uses in opto-electronic applications.[13]
One building block that is popular for use as the acceptor portion of organic dyads and
triads is the perylene diimide (PDI) chromophore. PDI has been thoroughly studied in many
optoelectronic applications owing to its commercial availability, high thermal stability, low lying
frontier molecular orbitals, high visible light absorption, and synthetic versatility.[14–18] PDI-based
dyads have been used in a wide variety of applications including studies on Forster resonance
energy transfer,[19] charge transfer,[20–23] water photooxidation,[24] fluorescence sensors,[25]
molecular logic operations,[26] and single component organic photovoltaics.[27,28] In the majority
of these systems, the donor unit is tethered to the PDI though the imide position via an alkyl,[21,25,29–
31] aryl,[23,24,27,28,32] or no linker[19,20] owing to ease of installing amine functionalized compounds
at the imide positions. There are only a few examples of PDI based dyads being tethered at bay
positions, either via alkoxy[26,33] or N-annulated[34] linkers.
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Owing to the many possible applications for these types of PDI materials, a more versatile
method toward the underexplored bay tethered dyads is attractive to expand the scope of donors
that can be tethered to the PDI. A wider scope of bay-tethered PDI dyads would facilitate the
exploration of the differences in the electronic and physical properties between imide and bay
linked dyads.
In this contribution we detail a synthetic pathway towards bay functionalized PDI based
molecular dyads. Our synthetic strategy centers on the functionalization of the PDI at the bay
position via N-annulation.[35–41] Three target materials are shown in Figure 1. The first target is the
dyad 4 (NPDIhexPTZ) based on a monomeric N-annulated PDI acceptor, tethered via a hexyl chain
and triazole ring to a phenothiazine donor. Each portion of this molecule was carefully chosen for
this system. The N-annulation at the bay position of the PDI chromophore is unique as it enables
alkyl chain substitution at a position other than the imides, allows free choice of imide side chains
to influence solubility and self-assembly, renders the PDI core prone to reversible oxidation, and
tethers the donor at the short axis of PDI (as opposed to the long axis when tethering via the imide)
will provide different supramolecular organization. The hexyl chain is a long, non-conjugated,
aliphatic linker that introduces flexibility between the donor and acceptor components. The triazole
unit, a result of utilizing copper catalyzed alkyne-azide cycloaddition (click) chemistry for the
rapid generation of the target materials, has been shown previously to be outside the redox window
of PDI-donor dyad systems.[31] Finally, phenothiazine was chosen as the donor because it is
electron rich relative to PDI and is known to form stable radical cations, enabling a long-lived
charged state which, has been utilized in dye sensitized solar cells and redox flow batteries, thus
serving as a good model donor.[42–44]
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This molecular design was further extended to dyad and triad systems based on a dimeric
N-annulated perylene diimide (NPDIhex2) acceptor. Dimeric PDI based materials have been
frequently used in high performance non-fullerene electron acceptors in organic solar cells,[36,45,46]
but have yet to be fully exploited in dyad/triad type systems with only one system reported to
date.[34] The dyad 9 (NPDIhex2PTZ) and triad 10 (NPDIhex2PTZ2) were targeted and contain a
dimeric NPDI based acceptor with one and two PTZ units, respectively, extending out from the N-
annulated bay position.
Figure 1: Top) Reference NPDI monomer NPDIhex, dimer NPDIhex2, and PTZ reference PTZeh.
Bottom) Target monomer-based dyad 4 (NPDIhexPTZ), dimer-based dyad 9 (NPDIhex2PTZ), and
dimer-based triad 10 (NPDIhex2-PTZ2).
2. Results and Discussion
2.1 Synthesis:
To synthesize 4 (NPDIhexPTZ) from previously synthesized 1 (NHPDI),[36] three reactions
must occur: alkylation of 1 (NHPDI) with a doubly functionalized alkyl chain, azide formation on
one end of the alkyl chain, and click between the azide functionalized alkyl chain and the acetylene
functionalized donor PTZ. The alkylation was performed before the azide was introduced to the
alkyl chain to avoid the synthesis of a potentially hazardous lightweight alkyl-azide. This route
4
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leaves the click reaction for the last step which increases the synthetic versatility when exploring
alternative donor components.
There are at least two extra steps involved in the synthesis of dyads/triads based on dimeric
NPDI2: bromination at one of the remaining bay positions of the NPDI and aryl-aryl coupling.
While brominating 4 (NPDIhexPTZ) would be ideal, it was ultimately unfeasible due to undesired
reactivity at the triazole and phenothiazine. Instead it was necessary to brominate a step earlier to
transform 3 (NPDIhexN3) to 5 (Br-NPDIhexN3) which was then clicked onto the donor and coupled
either asymmetrically or symmetrically to give the NPDI dimer based dyad and triad 9 (NPDIhex2
PTZ) and 10 (NPDIhex2PTZ2), respectively.
-
The first target was the monomeric NPDI dyad, 4 (NPDIhexPTZ), which was synthesized
in three steps from 1 (NHPDI) (Figure 2).[36] First, 1 (NHPDI) was alkylated with a large excess
of 1,6-dibromohexane thereby preventing the formation of an alkyl-linked dimer. Using standard
N-H alkylation conditions[36] with temperatures of 120 °C, the target product, 2 (PDIhexBr), was
formed, but a significant amount of alkene terminated side-product, a result of Br-elimination, was
observed and proved difficult to separate. Lowering the temperature from 120 °C to 60 °C
prevented the formation of the alkene side-product and gave 2 (PDIhexBr) in yields of 70%.
The reaction of compound 2 (NPDIhexBr) with excess NaN3 yielded the azide
functionalized compound 3 (NPDIhexN3) in yields up to 95%. The click reaction of 3 (NPDIhexN3)
with the alkyne functionalized donor PTZac (which was synthesized according to literature
procedure, see Figure 2)[47] resulted in the formation of the first targeted dyad, 4 (NPDIhexPTZ)
with 80% yield. Overall, 4 (NPDIhexPTZ) can be synthesized in 6 steps from commercially
available starting materials with a overall yield of 33% yield based on the perylene tetracarboxylic
dianhydride starting material.[36] The closely related, and only previously reported, NPDI dyad can
5
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be synthesized in only 4 steps, but with a much lower overall yield of ~5-10% depending on the
donor.[34] Therefore, the route presented here offers the significant advantage of a higher overall
yield.
Figure 2: Synthetic route towards the donor precursor 11 (PTZac) and the monomeric NPDI dyad 4
(NPDIhexPTZ).
The second target was the dimeric NPDI dyad, 9 (NPDIhex2PTZ), which requires an aryl-
aryl coupling reaction to form the dimeric NPDI. Our procedure involved the near quantitative
bromination of compound 3 (NPDIhexN3) to give compound 5 (BrNPDIhexN3). Compound 5
(BrNPDIhexN3) was then clicked with the alkyne functionalized 11 (PTZac) to give 6
(BrNPDIhexPTZ) in yields above 70%. To synthesize the target dyad, a coupling partner with a
transmetalating agent had to be synthesized. The two most common transmetalating groups are
boronic esters and trialkyl-tin groups for Suzuki and Stille reactions, respectively, and both are
known for PDI based materials.[48,49] While the borylation of PDI is known, borylations were
unable to be replicated on NPDIhex. Therefore, a Stille coupling reaction was utilized. Compound
7 (BrNPDIhex) was stannylated with hexabutylditin utilizing the catalyst SiliaCat® DPP-Pd to give
8 (Bu3SnNPDIhex) in 63% yield (Figure 3). An identified by-product was the dimer NPDIhex2
(Figure 1) which forms because of ligand redistribution during the catalytic cycle. The target
dimeric PDI dyad 9 (NPDIhex2PTZ) was successfully synthesized and isolated in 45% after
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column chromatography via the Stille cross-coupling reaction between 6 (BrNPDIhexPTZ) and 8
(Bu3SnNPDIhex) (Figure 3). Column chromatography is required to separate product 9
(NPDIhex2PTZ) from 4 (NPDIhexPTZ) which is produced as a minor side product.
Figure 3 Synthetic route toward dimeric NPDIhex dyad 9 (NPDIhex2PTZ) via Stille
reaction.
To explore an alternative route that avoided the use of organotin reagents, 9
(NPDIhex2PTZ) was synthesized via an asymmetric coupling based on our previously optimized
modified Negishi reaction (Figure 4).[36] The coupling of 6 (BrNPDIhexPTZ) and 7 (BrNPDIhex)
gave the target dimer 9 (NPDIhex2PTZ) in 38% yield. Considering the similar electronics of the
aryl-Br bonds it is unsurprising that the symmetric dimers NPDIhex2 and 10 (NPDIhex2PTZ2) were
also formed in 16% and 24% yield, respectively (78% total recovery). All compounds could be
separated from one another using silica-gel column chromatography.
7
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Figure 5: Synthetic route toward dimeric NPDI dyad 9 (NPDIhex2PTZ) via Negishi reaction.
The final target was the dimeric NPDI triad, 10 (NPDIhex2PTZ2). The direct synthesis was
easily achieved through the dimerization of 6 (BrNPDIhexPTZ) via using the modified Negishi-
type homocoupling with a 66% yield (Figure 5).
Figure 4: Synthetic route toward dimeric NPDI dyad 10
(NPDIhex2PTZ2) via Negishi reaction.
The three targets compounds 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), and 10 (NPDIhex2PTZ2)
were identified by 1H and 13C NMR spectroscopy, MALDI-TOF mass spectrometry, and elemental
analysis. Full spectra and analysis reports are provided in the supporting information.
2.2 NMR Spectroscopic Analysis
The chemical shifts of aromatic proton resonances of the PDI chromophore have been
shown to be very sensitive to the steric electronic environment.[50–52] For this reason the aromatic
region of the 1H NMR spectra of NPDIhex, 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), 10
1
(NPDIhex2PTZ2), and NPDIhex2 were compared (Figure 6). The H NMR spectrum of 4
8
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European Journal of Organic Chemistry
(NPDIhexPTZ) (Figure 6 – Red) shows two groups of aromatic proton resonances. The first set of
proton resonances is from 6.5 to 7.5 ppm attributed to the phenothiazine and triazole protons (ca.
7.2 ppm). The second set of resonances above 7.5 ppm are attributed to the PDI protons (as
confirmed by comparing to NPDIhex, see Figure 6 - Black). When comparing the spectra of 4
(NPDIhexPTZ) (Figure 6 – Red) and NPDIhex (Figure 6 – Black) there are only slight shifts of the
PDI based protons.
Comparing monomeric dyad 4 (NPDIhexPTZ) (Figure 6 – Red) to the dimeric dyad 9
(NPDIhex2PTZ) (Figure 6 – Blue) there are several distinct differences. First, the NPDI peaks
separate into 7 peaks consisting of 4 singlets, each integrating for one proton; two broad singlets,
each integrating for two protons, and a doublet of doublets integrating for 2 protons. The splitting
pattern here is reminiscent of the reference donor NPDIhex2 (Figure 2 – Purple) which consists of
Figure 6: Stacked 1H NMR spectra of NPDIhex (black), 4 (NPDIhexPTZ, red), 9 (NPDIhex2PTZ,
blue), 10 (NPDIhex2PTZ2, green), and NPDIhex2 (purple) in CDCl3. Peaks that correlate well
between 9 (NPDIhex2PTZ, blue) and 10 (NPDIhex2PTZ2, green), are indicated with green circles
and Peaks that correlate well between 9 (NPDIhex2PTZ, blue) and NPDIhex2 (purple), are indicated
with purple squares.
9
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three singlets and two doublets; each of which corresponds perfectly with a peak in 9
(NPDIhex2PTZ) (marked with purple squares). Resonances at 6.5-7.3 ppm in the spectrum of 9
(NPDIhex2PTZ) are attributed to the PTZ donor group. Unexpectedly the PTZ peaks in 9
(NPDIhex2PTZ) do not correspond exactly with the PTZ peaks in 4 (NPDIhexPTZ) which may
indicate some NPDI – PTZ interaction in 4 (NPDIhexPTZ) which is disrupted by the dimerization
of the NPDI in 9 (NPDIhex2PTZ).
Finally, looking at 10 (NPDIhex2PTZ2) (Figure 2 – Green) the NPDI based protons have
coalesced to 3 singlets and two doublets, similar to NPDIhex2, but each slightly shifted. The shifted
NPDI peaks are likely due to the interaction with the tethered PTZ as discussed above. Comparing
9 (NPDIhex2PTZ) to 10 (NPDIhex2PTZ2), it is evident that the peaks in 9 (NPDIhex2PTZ) that do
not correspond to NPDIhex2 correspond directly with 10 (NPDIhex2PTZ2) (marked with green
circles). Thus, the nature of the side-chain at the pyrrolic N-position has a slight impact on the
electronics of the NPDI core.
Based on the shifts of both the characteristic NPDI and PTZ resonances in the materials
studied, the chromophores have some interaction with each other in the solution phase, but the
nature of the interaction is dependent on whether the NPDI core is monomeric or dimeric.
2.3 Electrochemical Properties:
The electrochemical properties of 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), 10
(NPDIhex2PTZ2) were examined using cyclic voltammetry (see Figure 7 and Table 1, full analysis
can be found in the supporting information Figure S28). First, looking at 4 (NPDIhexPTZ) and
comparing to the reference compounds NPDIhex and PTZeh (see Figure 7A), 4 (NPDIhexPTZ) has
two fully reversible reduction events and two partially reversible oxidation events. Both reduction
10
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Figure 7: A) Stacked cyclic voltammetry plot of 4 (NPDIhexPTZ, red), compared to reference
compounds PDI (black) and PTZ (yellow). B) Stacked cyclic voltammetry plot of 4 (PDI-PTZ,
red), 9 (NPDIhex2PTZ, blue), and 10 (NPDIhex2PTZ2, green). Each trace has been individually
referenced to ferrocene, and current intensity has been normalized to the first reverse reduction
peak.
waves line up with the reference compound NPDIhex and are assigned to isolated one electron
reductions within the PDI core, which has previously shown to undergo two fully reversible
reductions.[17,36] The first of the two oxidation events (E1/2 0.34 V vs. Fc/Fc+) correlates with the
oxidation of PTZeh, and the second oxidation (E1/2 1.13 V vs. Fc/Fc+) correlates with the oxidation
of NPDIhex. The close correlation between 4 (NPDIhexPTZ) and the individual reference
compounds indicates that the triazole is not redox active in the region of interest, and that the
NPDIhex and PTZeh subunits are not in direct electronic communication.
Comparing the CV traces of 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), and 10 (NPDIhex2PTZ2)
there are three major changes (see Figure 7B). Looking at the reduction waves, there are two
reversible reductions for 4 (NPDIhexPTZ) but four reversible reductions each for 9
(NPDIhex2PTZ) and 10 (NPDIhex2PTZ2). The additional reduction waves are due to dimerized
PDI core since each individual PDI has two distinct reductions. The E1/2 of the first reduction
occurs at -1.30 V for 4 (NPDIhexPTZ) and -1.21 V for 9 (NPDIhex2PTZ) and -1.24 for 10
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(NPDIhex2PTZ2). The slight lowering of the reduction potential is a result of the dimerization of
the PDI core and has been observed previously.[36]
Compounds 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), and 10 (NPDIhex2PTZ2) all have two
partially reversible oxidations: one with E1/2 at ~0.32 V corresponding to oxidation of the PTZ
donor, and one with E1/2 at ~1.15 V which corresponds to the oxidation of the N-annulated PDI.
Importantly, the only major difference between the three compounds is the intensity of the
oxidation peak at ~0.32 V, which correlates to the different ratios of PDI to PTZ in each compound.
All oxidation waves occur at the same potential across all three compounds, indicating that the
oxidations are insensitive to the structural modifications and that the electronic communication is
minimal between the donor and acceptor chromophores.
Table 1: Tabulated electrochemical data for NPDIhex, 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), 10
(NPDIhex2PTZ2), and NPDIhex2. See SI Figure S28 for full analysis of CV traces.
Redonset EA
E1/2 Red
Oxonset
IP
E1/2 Ox
36
NPDIhex
-1.30
-1.13
3.5
3.7
N/A
0.90
0.24
5.7
5.0
N/A
4
-1.30, -1.55
0.34, 1.13
(NPDIhexPTZ)
9
-1.06
-1.08
-1.04
3.7
3.7
3.8
-1.21, -1.31, -1.55, -1.63
-1.24, -1.34, -1.55, -1.68
-1.24, -1.35, -1.53, -1.6641
0.26
0.23
1.2
5.1
5.0
6.0
0.32, 1.15
0.32, 1.13
N/A
(NPDIhex2PTZ)
10
(NPDIhex2PTZ2)
36
NPDIhex2
Electron affinity (EA) = 4.8 + E(Redonset). Ionization Potential (IP) = 4.8 + E(Oxonset). See SI
Materials and Methods and Figure S29 for onset determination.
2.4 Optical properties:
UV-Vis Absorption
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The optical absorption spectrum of 4 (NPDIhexPTZ) in solution is shown in Figure 8A.
The optical profile is dominated by strong absorption from 400 nm to 550 nm which is similar in
intensity and profile to that of NPDIhex and is typical of PDI based materials.[17] There is a small
increase in the absorption band in the high energy region of 4 (NPDIhexPTZ) relative to NPDIhex
(300-350 nm, see Figure 3A) which is attributed to localized transitions in the PTZ unit.
Figure 8: Solution UV-Vis (solid lines) and photoluminescence (dashed lines) spectra of 4
(NPDIhexPTZ, red) as well as reference compound NPDIhex with 0 (black) or 1 (blue) equivalent
of PTZeh. B) Thin film UV-Vis (solid lines) and photoluminescence (dashed lines) spectra of 4
(NPDIhexPTZ, red) as well as reference compound NPDIhex with 0 (black) or 1 (blue) equivalent
of PTZeh. NPDIhex was cast from 10 mg/mL solutions in chloroform on glass at 1500 RPM for 30
s. All other films were equimolar and cast from the same conditions as NPDIhex.
The optical absorption spectrum of 4 (NPDIhexPTZ) in thin film is shown in Figure 8B. As
in solution, the profile is dominated by the PDI absorption from 450 nm to 600 nm. Relative to the
solution profiles the main absorption band is broadened, the onset red shifted from 539 nm to 563
nm and the λmax moves from the lowest energy peak at 538 nm (0-0 vibronic transition), to the next
lowest energy peak at 500 nm (0-1 vibronic transition). Both the bathochromic shift and increase
in relative intensity of the 0-1 peak is attributed to π-stacking of the PDI chromophores, which is
expected when transitioning from solution to thin film absorptions.[53,54]
Unlike the solution profile, there are several major differences between the profiles of 4
(NPDIhexPTZ) and neat NPDIhex. First, the intensity is increased across the entire window which
likely indicates a thicker film. Second, the profile of the trace is markedly different; for NPDIhex
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the 0-0 peak (538 nm) is considerably less intense than the 0-1 peak (496 nm), but for 4
(NPDIhexPTZ) the 0-0 peak is nearly equal to the 0-1 peak. The reduced relative intensity of the
0-0 peak indicates less PDI π-stacking which is likely due to the steric hindrance of the tethered
phenothiazine.
Figure 9: Solution UV-Vis (solid lines) and photoluminescence (dashed lines) spectra of NPDIhex2
,
9 (NPDIhex2PTZ), and 10 (NPDIhex2PTZ2). B) Thin film UV-Vis (solid lines) and
photoluminescence (dashed lines) spectra NPDIhex2, 9 (NPDIhex2PTZ), and 10 (NPDIhex2PTZ2).
Films of NPDIhex2 were cast from 10 mg/mL solutions in chloroform on glass at 1500 RPM for 30
s. Other solutions were equimolar and cast from the same conditions as NPDIhex2
.
The optical absorption profiles of 9 (NPDIhex2PTZ) and 10 (NPDIhex2PTZ2) in solution
are shown in Figure 9A. Both profiles are dominated by the PDI absorption from 450-550 nm, and
both have an absorption band from 300-350 nm which is partially due to the phenothiazine. As
expected 9 (NPDIhex2PTZ) and 10 (NPDIhex2PTZ2) have nearly identical absorption profiles
except that the intensity of 9 (NPDIhex2PTZ) from 300 nm to 350 nm is slightly lower than that of
10 (NPDIhex2PTZ2) due to the additional PTZ unit on 10 (NPDIhex2PTZ2).
The optical absorption spectrum of 9 (NPDIhex2PTZ) and 10 (NPDIhex2PTZ2) in thin films
is shown in Figure 9B. In solution, the profile is dominated by the NPDIhex2 absorption from 450
nm to 625 nm. Relative to the solution profiles the main absorption band is broadened and the
onset of absorption red shifted from 545 nm to 551 nm. As depicted, above, the broadened,
redshifted absorption band indicates some extent of π-stacking in the solid state.
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Comparing to the reference compound NPDIhex2 there are some key differences in the thin
film absorption profiles. First, the overall intensity is higher which likely indicates a thicker film.
Second, in the thin film profile of NPDIhex2 there is a shoulder at ~600 nm, but this shoulder is
smaller in 9 (NPDIhex2PTZ) and is completely absent in 10 (NPDIhex2PTZ2). Additionally, in
NPDIhex2, the 0-0 peak at 540 nm is less intense than the 0-1 peak at 497 nm, but in 9
(NPDIhex2PTZ) the 0-0 peak (530 nm) is slightly more intense than the 0-1 peak (499 nm), and in
10 (NPDIhex2PTZ2) the 0-0 peak (539 nm) is considerably more intense than the 0-1 peak (501
nm). The relative intensity of the 0-0 and 0-1 peaks as well as the significant low energy shoulder
indicates that NPDIhex2 exhibits a strong tendency to aggregate in the solid-state,[55] but 9
(NPDIhex2PTZ) and 10 (NPDIhex2PTZ2) have inhibited aggregation indicating that each additional
phenothiazine might be preventing the NPDI dimers from forming organized supramolecular
structures.
Photoluminescence
To further probe the potential interaction between the donor and acceptor chromophores
we examined the solution and thin film light emission characteristics. The photoluminescence (PL)
spectra of compounds 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), and 10 (NPDIhex2PTZ2) and a model
system containing equimolar amounts of non-tethered chromophores are shown in Figures 8 and
9.
Comparing the solution PL spectrum of 4 (NPDIhexPTZ) to the PL spectra of either neat
NPDIhex, or the model system NPDIhex + PTZeh in solution, the emission of the tethered system 4
(NPDIhexPTZ) is reduced by 83% (See Figure 8A, Table 2). Since PDI absorbs lower energy than
PTZ, the fluorescence quenching is not a result of Forster resonance energy transfer but rather is a
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result of a charge transfer between the donor and acceptor chromophores. Since the PL quenching
is only observed in 4 (NPDIhexPTZ) and not in the equimolar model system, the charge transfer
must be dependent on both the presence and proximity of the donor component.
Comparing the thin film PL spectrum of 4 (NPDIhexPTZ) to the PL spectra of either neat
NPDIhex, or the model system NPDIhex + PTZeh in thin film, the emission of the tethered system
4 (NPDIhexPTZ) is reduced by 31% and the blend system is reduced by 10% (See Figure 8B, Table
2). This quenching indicates that in the solid state the PTZ donor can quench the emission of
NPDIhex. However, in the blended films (NPDIhex + PTZeh) the PL quenching efficiency is less
than that of films of the tethered system 4 (NPDIhexPTZ). This indicates that phase separation
occurs between NPDIhex and PTZeh in the solid state and highlights the uniqueness of the tethered
system
When comparing the PL spectra of 9 (NPDIhex2PTZ) and 10 (NPDIhex2PTZ2) to NPDIhex2
,
the emission of 9 (NPDIhex2PTZ) is quenched by 89% and 10 (NPDIhex2PTZ2) is quenched by
96%. This is consistent with the increasing number of PTZ units (See Figure 4). The non-tethered
models show no PL quenching in solution (See SI Figure S28).
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As thin films, nearly complete PL quenching is observed for both 9 (NPDIhex2PTZ) and
10 (NPDIhex2PTZ2) (see Figure 9), and for both blended systems (See Figure S29). The high PL
quenching in all cases indicates that like the monomeric NPDIhex based materials, PTZ does
quench the emission from NPDIhex. Unlike NPDIhex, NPDIhex2 is miscible with PTZeh and
therefore minimal phase separation is observed, and the PL quenching is high in both tethered and
blended films.
Table 2: Tabulated spectral data for 4 (NPDIhexPTZ), 9 (NPDIhex2PTZ), and 10
(NPDIhex2PTZ2).
State
λmax
(nm)
ε
λonset
PL λmax
(nm)
Quenching
%
(L/mol*cm) (nm)
4
Sln
Film
Sln
530
500
533
530
533
539
65 500
N/A
539
563
545
551
545
551
545
581
590
579
590
581
83 %
31 %
89 %
88 %
96 %
90 %
(NPDIhexPTZ)
9
128 600
N/A
(NPDIhex2PTZ)
Film
Sln
10
132 800
N/A
(NPDIhex2PTZ2)
Film
3. Conclusion:
We have successfully developed new synthetic methods towards PDI based molecular
dyads and triads. Our strategy involves using an N-annulated PDI for which donor components
are tethered via the pyrrolic N-atom position.
As a proof of concept, three materials were synthesized, one dyad based on a monomeric
1
NPDI as well as a dyad and triad each based on an NPDI dimer. A close examination of the H
NMR spectra showed that there is only minimal solution-state interaction between the PDI
acceptor and PTZ donor. Additionally, this interaction is altered by the steric environment around
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the PDI. Further characterization by CV indicates that the frontier orbitals of the donor and
acceptor are independent from each other. Similarly, the UV-Vis spectra showed that the absorption
profile is well-modelled by a liner combination of the donor and acceptor units which further
indicates minimal electronic communication between the chromophores. An important difference
is visible in the fluorescence spectra where the dyads and triads exhibit significant PL quenching.
Finally, this work provides a facile method for the synthesis of donor-acceptor systems
based on NPDI monomers and dimers where the aromatic systems are not in direct electronic
communication may serve as useful materials for ambipolar OFETS and single component OPVs.
4. EXPERIMENTAL
PTZac (11): To a 10-20 mL microwave vial with a stir bar was added Phenothiazine (1000 mg, 5
mmol), sodium carbonate (835 mg, 7.5 mmol) and toluene (10 ml). The vial was capped and
purged with N2 for 15 minutes. To the reaction mixture was added propargyl bromide (2.3 mL, 2.9
g, 25 mmol). The solution was heated to 110 °C in a bead bath with stirring. After 20 h the reaction
was extracted with 1 M HCl in water. The organic phase was dried with brine. The solvent was
removed on a rotatory evaporator and the solid was filtered from methanol. The solid was purified
by column chromatography (hexanes  50% CH2Cl2 in hexanes) to give crude PTZac. Crude 11
was additionally purified via recrystallization from methanol to further to give PTZac (171 mg,
14%) as a white crystalline solid. 1H NMR: (500 MHz, CDCl3) δ 7.20 (dtd, J = 9.5, 8.1, 1.4 Hz,
4H, aryl), 7.14 (dd, J = 7.6, 1.3 Hz, 2H, aryl), 6.96 (td, J = 7.4, 1.4 Hz, 2H, aryl), 4.53 (d, J = 2.4
Hz, 2H, methylene), 2.46 (t, J = 2.4 Hz, 1H, alkynyl).
NPDIhexBr (2): To a 10-20 mL microwave vial with a stir bar was added NHPDI (500 mg, 0.92
mmol) and potassium carbonate (253 mg, 1.8 mmol). The vial was capped and 7 mL DMF was
added. The vial was purged with N2 for 15 min. To the vial was added 1,6-dibromohexane (0.7
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mL, 1.1g, 4.6 mmol). The reaction mixture was heated in a bead bath at 60 °C for 2 h. After TLC
indicated the starting material had been completely consumed, the reaction mixture was diluted
with 50 mL MeOH and filtered. The collected solid was washed multiple times with water and
methanol to remove residual carbonates and 1,6-dibromohexane. The red solid was collected and
dried in a vacuum desiccator over night to provide dry NPDIhexBr (460 mg, 71%) as a dark red
powder. MALDI: Theoretical: M+ 705.22 Found: 705.2185. 1H NMR: (500 MHz, CDCl3) δ 8.92
(s, 2H, PDI Aryl), 8.88 (d, J = 8.0 Hz, 2H, PDI Aryl), 8.80 (br-d, J = 8.0 hz, 2H, PDI Aryl), 5.29
– 5.18 (m, 2H), 4.91 (t, J = 7.1 Hz, 2H), 3.36 (t, J = 6.7 Hz, 2H, CH2-Br), 2.43 – 2.31 (m, 4H),
2.24 (dt, J = 14.7, 7.2 Hz, 2H), 2.07 – 1.96 (m, 4H), 1.86 – 1.79 (m, 2H), 1.56 – 1.43 (m, 4H), 0.99
13
(t, J = 7.5 Hz, 12H). C NMR: (126 MHz, CDCl3) δ 134.21, 132.14, 124.12, 123.36, 121.29,
119.01, 57.22, 46.19, 32.84, 31.84, 30.78, 27.17, 25.83, 24.67, 10.92.
NPDIhexN3 (3): To a 100 mL round bottom flask with a stir bar was added NPDIhexBr (400 mg,
0.56 mmol), sodium azide (70 mg, 1.1 mmol) and DMF (20 mL). The reaction was capped with a
septum and stirred at room temperature for 3 h. When TLC indicated complete consumption of the
NPDIhexBr the reaction mixture was diluted to 100 mL with Methanol and 10 mL of water was
added to ensure the product had fully precipitated. The reaction mixture was filtered to give
NPDIhexN3 as a bright red solid (372 mg, 89%). No further purification was necessary. MALDI:
Theoretical: M+ 668.31 Found: 668.3098. 1H NMR: (500 MHz, CDCl3) δ 8.95 (s, 2H, PDI Aryl),
8.93 (d, J = 8.0 Hz, 2H, PDI Aryl), 8.83 (s, 2H, PDI Aryl), 5.23 (s, 2H), 4.92 (t, J = 7.1 Hz, 2H),
3.24 (t, J = 6.7 Hz, 2H, CH2N3), 2.42 – 2.31 (m, 4H), 2.25 (s, 2H), 2.01 (tt, J = 14.7, 7.4 Hz, 4H),
13
1.53 – 1.43 (m, 4H), 0.99 (t, J = 7.5 Hz, 12H). C NMR: (126 MHz, CDCl3) δ 134.28, 132.22,
124.18, 123.42, 121.37, 119.10, 57.21, 50.61, 46.22, 30.85, 28.08, 26.23, 25.83, 24.67, 10.91.
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NPDIhexPTZ (4): To a 10-20 mL microwave vial with a stir bar was added NPDIhexN3 (100 mg,
0.15 mmol), PTZac (38 mg, 0.16 mmol), copper sulfate (4 mg, 0.015 mmol), and sodium ascorbate
(10 mmol 0.05 mmol). The vial was capped and purged with nitrogen for 10 min. 10 mL of a
previously degassed 7:3 mixture of THF:water was cannula transferred to the reaction vial before
heating to 60 °C for 18h. After TLC indicated complete consumption of the PDI starting material,
the reaction was diluted with 50 mL CH2Cl2 and washed with water, dried with brine and
magnesium sulfate, filtered through silica and the solvent was removed on a rotatory evaporator.
The oily product was re-dissolved in CH2Cl2 and filtered through silica. Impurities were eluted
with CH2Cl2 and the product eluted with EtOAc. The resulting solution was slurried with silica
and alumina for 45 minutes before filtering through alumina. The solvent was removed on a
rotatory evaporator and filtered with methanol to give NPDIhexPTZ as a dark red solid (108 mg,
80%). MALDI: Theoretical: M + Na+ 928.36 Found: 928.3619. CHN: Theoretical: % C: 72.90,
H: 5.67, N: 10.82. Found: % C: 72.51, H: 5.49, N: 10.51. 1H NMR: (500 MHz, CDCl3) δ 9.02 (d,
J = 8.0 Hz, 2H (PDI Aryl), 8.97 (s, J = 8.0 Hz, 2H, PDI Aryl), 8.88 (s, 2H, PDI Aryl), 7.25 (s, 2H,
Triazole), 7.05 (dd, J = 7.6, 1.5 Hz, 2H, Ptz), 6.99 (ddd, J = 8.2, 7.5, 1.5 Hz, 2H, Ptz), 6.83 (td, J
= 7.5, 1.1 Hz, 2H, Ptz), 6.72 (dd, J = 8.2, 0.8 Hz, 2H, Ptz), 5.26 – 5.18 (m, 2H, PDI imide), 5.16
(s, 2H, Ptz CH2), 4.84 (t, J = 7.0 Hz, 2H, PDI CH2), 4.22 (t, J = 7.1 Hz, 2H, Taz CH2), 2.41 – 2.24
(m, 4H), 2.18 – 2.09 (m, 2H), 1.99 (qt, J = 11.0, 5.5 Hz, 4H), 1.82 – 1.74 (m, 2H), 1.41 (dt, J =
15.3, 7.6 Hz, 2H), 1.28 (dt, J = 15.1, 7.5 Hz, 2H), 0.97 (t, J = 7.5 Hz, 12H). 13C NMR: (75 MHz,
CDCl3) δ 144.81, 144.22, 134.83, 132.82, 127.28, 127.13, 124.76, 124.04, 123.85, 122.75, 122.26,
119.69, 115.23, 57.79, 50.10, 44.90, 31.31, 29.93, 26.61, 26.00, 25.24, 11.49.
BrNPDIhexN3 (5): to a 100 mL round bottom flask with a stir bar was added NPDIhexN3 (350 mg,
0.52 mmol), CH2Cl2 (25 mL) and liquid bromine (1 pipette, ~1.25 mL, large excess). The reaction
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was capped with a septum and stirred at room temperature for 30 min. When TLC indicated
complete consumption of NPDIhexN3 the reaction mixture was quenched with saturated aqueous
sodium bisulfite. The reaction mixture was then extracted with 2 times 50 mL saturated aqueous
sodium bisulfite followed by drying with 2 times 50 mL brine. The organic phase was dried with
magnesium sulfate and filtered through silica. The solvent was removed on a rotary evaporator.
The product was dissolved in a minimum amount of CH2Cl2 and 50 mL MeOH was added. The
CH2Cl2 was removed on a rotary evaporator. The suspended solid was filtered to give
BrNPDIhexN3 as a dark red solid (365 mg, 93%). No further purification was necessary. MALDI:
+
1
Theoretical: M+H 745.21 Found: 745.2165. H NMR: (500 MHz, CDCl3) δ 9.90 (s, 2H, PDI
Aryl), 9.00 (s, J = 8.1 Hz, 4H, PDI Aryl), 8.90 (d, J = 8.1 Hz, 2H, PDI Aryl), 5.28 – 5.16 (m, 2H,
PDI Imide), 4.83 (t, J = 5.8 Hz, 2H, PDI CH2), 3.23 (t, J = 6.7 Hz, 2H, CH2N3), 2.44 – 2.31 (m,
4H), 2.21 (s, 2H), 2.05 (td, J = 13.7, 6.8 Hz, 4H), 1.56 (dd, J = 12.2, 4.0 Hz, 4H), 1.00 (p, J = 7.6
Hz, 12H). 13C NMR: (126 MHz, CDCl3) δ 133.76, 133.54, 131.56, 129.63, 126.80, 123.48,
122.88, 122.53, 121.36, 120.76, 118.03, 117.60, 76.71, 76.45, 76.20, 57.50, 57.35, 50.59, 46.08,
30.69, 28.05, 26.21, 25.79, 24.64, 24.58, 11.01, 10.97.
BrNPDIhexPTZ (6): To a 10-20 mL microwave vial with a stir bar was added BrNPDIhexN3 (225
mg, 0.3 mmol), PTZac (71 mg, 0.3 mmol), copper sulfate (8 mg, 0.03 mmmol) and sodium
ascorbate (14 mg, 0.06 mmol). The vial was capped, and the headspace purged with nitrogen for
15 min. To the vial was added 20 mL of a previously degassed mixture of 7:3 THF: H2O. The
reaction was heated to 60 °C for 2 hours. When TLC indicated complete consumption of the
starting material, the reaction was diluted to 50 mL with CH2Cl2 and extracted with CH2Cl2 and
brine. The organic phase was dried with brine and filtered. The solvent was removed on rotatory
evaporator to give crude BrNPDIhexPTZ. The product was purified by taking up in CH2Cl2 and
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filtering through silica. CH2Cl2 was passed through silica until it ran clean, leaving the product as
a red band at the top of the silica plug. CH2Cl2 with 10% methanol was passed through the silica
to isolate BrNPDIhexPTZ. The solvent was removed on a rotatory evaporator and the resulting red
solid was filtered from methanol (216 mg, 73%). MALDI: Theoretical: M+ 983.28 Found:
983.2928. 1H NMR: (500 MHz, CDCl3) δ 10.14 (d, J = 8.3 Hz, 1H, PDI Aryl), 9.02 (s, 1H, PDI
Aryl), 8.95 (s, 2H, PDI Aryl), 8.84 (d, J = 7.2 Hz, 1H, PDI Aryl), 7.26 – 7.25 (m, 1H, Taz Aryl),
7.04 (dt, J = 5.0, 2.5 Hz, 2H, Ptz Aryl), 7.02 – 6.96 (m, 2H, Ptz Aryl), 6.86 – 6.80 (m, 2H, Ptz
Aryl), 6.72 (dd, J = 8.2, 0.9 Hz, 2H, Ptz Aryl), 5.26 – 5.17 (m, 2H, PDI Imide), 5.16 (s, 2H, Ptz
CH2), 4.86 (t, J = 7.1 Hz, 2H, PDI CH2), 4.21 (dt, J = 14.2, 7.1 Hz, 2H, Taz CH2), 2.43 – 2.28 (m,
4H), 2.17 – 2.08 (m, 2H), 2.08 – 1.97 (m, 4H), 1.83 – 1.75 (m, 2H), 1.40 (dt, J = 10.7, 7.6 Hz, 2H),
13
1.27 (dt, J = 9.7, 7.7 Hz, 2H), 1.05 – 0.95 (m, 12H). C NMR: (126 MHz, CDCl3) δ 144.24,
143.64, 133.97, 133.76, 127.16, 126.70, 126.56, 123.72, 123.28, 122.74, 122.17, 121.68, 121.03,
118.40, 117.95, 114.65, 76.71, 76.45, 76.20, 57.47, 57.32, 49.51, 46.00, 44.31, 30.63, 29.33, 26.03,
25.41, 24.65, 24.59, 10.95, 10.91.
Bu3SnNPDIhex (8): To a 10-20 mL microwave vial with a stir bar was added BrNPDIhex (800
mg, 1.13 mmol) and SiliaCat® DPP-Pd (440 mg, 0.13 mmol Pd). The reaction vial was brought
into a glovebox where hexabutyldistannane (0.8 mL, 800 mg, 1.24 mmol) was added. The vial was
capped and removed from the box where 20 mL of previously degassed toluene was added. The
reavtion was heated to 100 °C with stirring for 1 hour. When TLC indicated complete consumption
of BrNPDIhex, the reaction was filtered through a silica plug with hexanes to remove residual
hexabutyldistannane, 2:1 CH2Cl2: hexanes to collect the desired product and acetone to recover
the dimerized product. The solvent was removed on a rotatory evaporator to give Bu3SnNPDIhex
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as a dark red viscous oil (630 mg, 0.069 mmol, 63%). This material was used “as-is” without
further purification.
NPDIhex2PTZ (9): Via Stille: To a 5-10 mL microwave vial with a stir bar was added
BrNPDIhexPTZ (107 mg, 0.11 mmol). The vial was then brought into a glove box where Pd(PPh3)4
(15 mg, 0.012 mmol) was added. The vial was capped and removed from the glove box. To the
vial was added 1.5 mL of a 100 mg/mL solution of crude Bu3SnNPDIhex (~150 mg, 0.16 mmol)
and 9 mL previously dried and degassed toluene. The reaction mixture was sparged with N2 for 25
min before the reaction was heated in a microwave to 180 °C for 2h. TLC determined the complete
consumption of Bu3SnNPDIhex. The reaction mixture was filtered through a silica plug to remove
the catalyst. The solvent was removed on a rotatory evaporator to give a crude NPDIhex2PTZ. The
product was purified via column chromatography with CH2Cl2 with 2% methanol as eluent to give
NPDIhex2PTZ (75.3 mg, 0.049 mmol, 45%) as a dark red powder. This method of purification was
unable to separate the desired product from a small amount of residual PDI-C6PTZ.
NPDIhex2PTZ (9): Via Negishi: To a 5-10 mL microwave vial with a stir bar was added
BrNPDIhexPTZ (50 mg, 0.05 mmol), BrNPDIhex (36 mg, 0.05 mmol), and zinc (32 mg, 0.49
mmol). The vial was brought into a glove box where Pd2DBA3 (30 mg, 0.036 mmol) was added.
The vial was capped and removed from the glove box. To the vial was added dry, degassed DMF
(10 mL) before the reaction vial was sparged with N2 for 10 min. The reaction was heated to 100
°C with stirring for 75 min. When TLC (40% EtOAc in toluene as eluent) showed complete
consumption of the starting materials, the reaction mixture was filtered through a silica plug with
CH2Cl2. The solvent was removed on a rotatory evaporator to yield the crude product. The product
was purified via column chromatography with a toluene to EtOAc gradient, holding at 40% EtOAc
until the desired product band was completely removed. Evaporation of the solvent on a rotatory
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evaporator, followed by isolation with methanol yielded NPDIhex2PTZ as a dark red solid (29 mg,
0.019 mmol, 38%). CHN: Theoretical: % C: 74.49, H: 5.92, N: 9.14. Found: % C: 74.21, H: 5.91,
N: 9.04. 1H NMR: (500 MHz, CDCl3) δ 9.28 (s, 1H, PDI Aryl), 9.23 (s, 1H, PDI Aryl), 9.10 (s,
1H, PDI Aryl), 9.05 (s, 1H, PDI Aryl), 8.89 (s, 2H, PDI Aryl), 7.97 (s, 2H, PDI Aryl), 7.71 (dd, J
= 8.4, 2.2 Hz, 2H, PDI Aryl), 7.30 (d, J = 15.1 Hz, 1H, Taz), 7.09 (dd, J = 7.6, 1.4 Hz, 2H, Ptz
Aryl), 7.04 (td, J = 8.2, 1.5 Hz, 2H, Ptz Aryl), 6.87 (td, J = 7.5, 1.0 Hz, 2H, Ptz Aryl), 6.77 (dd, J
= 14.3, 6.8 Hz, 2H, Ptz Aryl), 5.21 (s, 4H, PDI Imide CH, PTZ-CH2), 5.01 (two triplets, J = 24.1,
7.1 Hz, 6H, PDI Imide CH, 2x PDI CH2), 4.29 (t, J = 7.0 Hz, 2H, Taz CH2), 2.46 – 2.29 (m, 6H),
2.28 – 2.12 (m, 6H), 2.07 – 1.94 (m, 4H), 1.93 – 1.77 (m, 6H), 1.60 – 1.50 (m, 4H), 1.50 – 1.42
(m, 2H), 1.42 – 1.33 (m, 4H), 1.08 – 0.97 (m, 12H), 0.92 (dd, J = 14.9, 7.7 Hz, 3H), 0.83 (s, 11H).
13C NMR: (126 MHz, CDCl3) δ 144.30, 143.69, 140.41, 140.23, 134.69, 134.61, 134.47, 134.38,
132.35, 132.29, 129.84, 129.79, 126.75, 126.60, 126.33, 126.23, 124.39, 124.14, 123.31, 123.00,
122.21, 122.17, 121.74, 119.55, 119.52, 119.28, 119.25, 114.70, 76.71, 76.45, 76.20, 57.45, 57.04,
49.58, 46.57, 46.23, 44.37, 31.12, 30.89, 29.40, 26.44, 26.15, 25.51, 24.61, 24.46, 21.97, 13.46,
10.97, 10.69.
NPDIhex2PTZ2 (10): To a 10-20 mL microwave vial with a stir bar was added BrNPDIhexPTZ
(125 mg, 0.13 mmol) and zinc dust (42 mg, 0.66 mmol). The vial was brought into a glove box
where Pd2DBA3 (20 mg, 0.02 mmol) was added. The vial was capped and removed from the glove
box where 5 mL previously degassed DMF was added via cannula. The reaction was heated to 100
°C in a bead bath with stirring for 2.5 h when the solution had turned a dark blue. When TLC
indicated complete consumption of starting material, the reaction was diluted to 75 mL with
CH2Cl2 and an additional 10 mL of methanol was added. The resulting solution was filtered
through silica to remove most of the palladium catalyst and zinc. The solvent was removed on a
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10.1002/ejoc.201801383
European Journal of Organic Chemistry
rotatory evaporator. The resulting solid was redissolved in CH2Cl2 and filtered through silica again
to remove any remaining traces of catalyst and zinc. The crude product was purified by column
chromatography with a hexanes to EtOAc gradient. Combined fractions were slurried with celite
and alumina before filtering from alumina to remove all metal contamination and neutralize acidic
sites. Solvent was removed on a rotatory evaporator and NPDIhex2PTZ2 was isolated as a fine red
powder (75 mg, 66%). MALDI: Theoretical: M + Na+ 1831.72 Found: 1831.59. CHN:
Theoretical: % C: 72.99, H: 5.57, N: 10.83. Found: % C: 72.05, H: 5.43, N: 10.65. 1H NMR: (300
MHz, CDCl3) δ 9.25 (s, 2H, PDI Aryl), 9.07 (s, 2H, PDI Aryl), 8.90 (s, 2H, PDI Aryl), 7.98 (d, J
= 8.1 Hz, 2H, PDI Aryl), 7.73 (d, J = 8.3 Hz, 2H, PDI Aryl), 7.33 (s, 2H, Taz), 7.07 (m, 8H, Ptz
Aryl), 6.95 – 6.84 (m, 4H, Ptz Aryl), 6.78 (d, J = 8.1 Hz, 4H, Ptz Aryl), 5.22 (s, 6H, Ptz-CH2, PDI
Imide CH), 5.00 (t, J = 6.8 Hz, 6H, PDI Imide CH, PDI-CH2), 4.31 (t, J = 7.0 Hz, 4H, Taz-CH2),
2.36 (s, 4H), 2.26 (m, 8H), 2.09 – 1.95 (m, 4H), 1.89 (m, 8H), 1.53 (m, 4H), 1.44 – 1.32 (m, 4H),
1.02 (t, J = 7.3 Hz, 12H), 0.83 (br s, 12H). 13C NMR: (75 MHz, CDCl3) δ 144.88, 144.88, 144.27,
144.27, 134.97, 127.33, 127.33, 127.18, 127.18, 123.89, 123.89, 122.79, 122.79, 122.32, 122.32,
115.28, 115.28, 50.16, 50.16, 44.94, 44.94, 33.04, 31.46, 29.97, 29.97, 26.73, 26.08, 25.03, 11.27,
11.27.
ASSOCIATED CONTENT
1
13
Supporting Information: Materials and Methods, H and C NMR spectra, MALDI spectra, EA
results and supplementary figures (NMR, Full CV analysis, and UV-vis/PL spectra) are available
free of charge via the Internet
AUTHOR INFORMATION
Corresponding Author
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10.1002/ejoc.201801383
European Journal of Organic Chemistry
* Gregory C. Welch.
ACKNOWLEDGMENT
GCW acknowledges NSERC DG (435715-2013), CFI JELF (34102), CRC, and the U of C. JRC
acknowledges the Province of Alberta as well as the U of C Faculty of Graduate Studies for
graduate scholarships
Key Words: Organic Dyes, Perylene Diimide, N-Annulation, Phenothiazine, Molecular Dyads
and Triads
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TOC Text
Synthesis of monomeric and dimeric perylene diimide dyads and triads via N-annulation at the
bay position
TOC Graphic
Monomer
Dimer
Dyad
Triad
29
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