Porphyrin-Hexaphenylbenzene Conjugates via Mixed Cyclotrimerization Reactions

Article abstract of DOI:10.1021/acs.joc.8b02907

Mixed cyclotrimerization reactions of diarylacetylenes (tolans) were applied to generate a library of multiple porphyrin-hexaphenylbenzene (HPB) architectures. Successful reactions, which could be influenced by the ratio of tolan starting materials, were

Full text of DOI:10.1021/acs.joc.8b02907

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Article
Porphyrin-Hexaphenylbenzene Conjugates
via Mixed Cyclotrimerization Reactions
Max M. Martin, Maximilian Dill, Jens Langer, and Norbert Jux
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.8b02907 • Publication Date (Web): 31 Dec 2018
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Porphyrin-Hexaphenylbenzene Conjugates via Mixed
Cyclotrimerization Reactions
Max M. Martin,[a] Maximilian Dill,[a] Jens Langer[b] and Norbert Jux*[a]
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[a]
[b]
Department Chemie und Pharmazie & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-
Universität Erlangen-Nürnberg, Nikolaus-Fiebiger-Str. 10, 91058 Erlangen (Germany),
norbert.jux@fau.de.
Inorganic and Organometallic Chemistry, Egerlandstr. 1, 91058 Erlangen (Germany),
jens.langer@fau.de.
Entry for the Table of Contents
Porphyrin-Hexaphenylbenzene-Conjugates
ortho
meta
para
Abstract: Mixed cyclotrimerization reactions of diarylacetylenes (tolans) were applied in order to
generate library of multiple-porphyrin-hexaphenylbenzene (HPB) architectures. Successful
a
reactions, which could be influenced by the ratio of tolan starting materials, were conducted using
dicobaltoctacarbonyl as a catalyst. Separation of the reaction products was performed by
chromatographic and crystallization techniques. The physical properties were investigated with
respect to the number of porphyrins per HPB and their substitution pattern.
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Introduction
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Multiple porphyrin architectures with different structural features were synthesized for mimicking the
processes of photosynthesis.1-10 One approach, which is based on hexaphenylbenzene (HPB)
scaffolds meso-connected to porphyrins, was first reported in 2002 and showed similar properties to
the light-harvesting antenna LH2 in purple bacteria.11-12 This was followed by further HPB-light
harvesting arrays.13-16 The concept was expanded by the introduction of different functional groups,
e.g. antenna molecules or pH sensitive dyes, close to the porphyrins resulting in systems which mimic
crucial photophysical processes such as nonphotochemical quenching.17-18 Utilizing the sixfold
geometry of HPBs as a template succeeded in constructing cyclic, wheel shaped light-harvesting
architectures.19-24 As HPBs and related compounds emerged as a versatile building block in organic
synthesis, much effort is being invested into the development of novel synthetic strategies.25-29 Yet,
their synthesis is dominated by two major routes: The [2+2+2] metal-catalyzed cyclotrimerization30 of
tolans and the [4+2] Diels-Alder reaction31 of tetraarylcyclopentadienones with tolans. Attractive
features such as a low number of synthetic steps as well as high yields still qualify these as reactions
of choice for HPB derivatives. The remarkable variety of possible HPB substitution pattern allows for, if
controllable, the specific placement of “active” components for light harvesting and energy/electron
transfer such as fullerenes or porphyrins.13-18 The precise control over the molecular structure of
functionalized HPBs is intended to study the correlation of physical properties with the respective
substitution pattern. Hence, a library of porphyrin-HPBs was needed, in which the relative
configuration as well as the number of chromophores is altered. We have recently introduced a
method for controlling the substitution patterns of HPBs which may be suitable for synthesis of
porphyrin-HPBs.27 However, a statistical approach of mixed cyclotrimerization reactions seems to be a
promising choice for producing a series of light-harvesting porphyrin-HPB systems faster, with less
effort in synthesis but with possible separation and purification issues. Therefore, the following paper
reports the synthesis of porphyrin-HPBs via mixed cyclotrimerization reactions, their isolation and
characterization.
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Results and Discussion
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The literature provides one example for a mixed cyclotrimerization reaction with porphyrins
(Scheme 1),17 in which the doubly substituted porphyrin tolan 1 was reacted with a mono substituted
tolan 2. The desired product 3 was obtained in 18 % yield as well as hexa-substituted HPB 4 as a
byproduct. However, additional five porphyrin-HPB byproducts are expected in this statistical reaction,
which were not mentioned in the publication.
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Scheme 1. Example of a mixed cyclotrimerization in the literature.[17]
With the goal of producing a library of multi-porphyrin-HPBs for studying their structure – physical
properties relation, we investigated the concept of mixed cyclotrimerizations in more detail. Therefore,
we started with para-substituted tolans 5 and 6 (Scheme 2) having either both sides occupied with
porphyrins or tert-butyl groups, respectively. Cyclotrimerization in this case is intended to yield three
porphyrin-HPB products and additionally hexa-tert-butyl substituted HPB 7. Porphyrin-tolan 5, as well
as tert-butyl-tolan 632 were prepared under standard Sonogashira conditions (see experimental
section), mixed in a 2:1 ratio and reacted under cobalt carbonyl catalysis in refluxing toluene. Here, an
excess amount of cobalt catalyst (2.25 equiv) was necessary for obtaining good conversion results.
After heating for 16 h, the nickel porphyrins were subsequently demetalated with concentrated sulfuric
acid due to better separation properties of the free base porphyrins. The three porphyrin-HPB
conjugates 8, 9, and 10 as well as hexa-tert-butyl-HPB 7 were successfully separated by a
combination of size exclusion and silica gel column chromatography. Porphyrin-HPBs 8, 9, and 10
were obtained in 12 %, 39 % and 11 % yields, respectively, whereas the yield of hexa-tert-butyl-HPB 7
could not be determined since too little (< 1 mg) was formed. In total, the yield of porphyrin-HPBs was
62 % and the distribution showed, that the formation of a desired product can be influenced by the
molar ratio of tolans. Reaction of a 2:1 mixture of tolans 5 and 6 favored the formation of tetra-
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porphyrin-HPB 9. Apparently, both tolans have a similar reactivity towards cyclotrimerization reactions
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although their steric and electronic properties differ significantly.
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Scheme 2. Mixed cyclotrimerization A: Two equivalents of 5 and one equivalent of 6 yielding three porphyrin-HPB products. Hexa-tert-butyl-
HPB 7 was formed only in minor quantities (< 1 mg) and therefore no yield was determined.
Next, we explored another mixed cyclotrimerization for the preparation of porphyrin-HPB conjugates
by reacting tolan 6 with a mono-porphyrin substituted tolan 11. This reaction should, due to the lower
symmetry of 11, result in six porphyrin-HPB conjugates plus hexa-tert-butyl-HPB 7 (Scheme 3). The
starting materials were brought into the reaction in a ratio of 2:1 for 11 and 6, respectively, with the
aim of favoring the formation of di-substituted porphyrin-HPBs 8, 15 and 16. The reaction was
performed under similar conditions to the previous one, although this time catalytic amounts of
dicobaltoctacarbonyl (0.30 equiv) were sufficient for complete conversion of starting material. Owing to
the high number of products, with similarities in size and polarity, separation of the products was
expected to be hampered. Nevertheless, porphyrin-HPBs 8, 12, 13, 14 were successfully separated
using chromatographic techniques and only meta/para conjugates 15, 16 could not be isolated
separately. The total yield of porphyrin-HPBs was 61 % and as intended di-substituted systems 8, 15,
16 formed the major fraction with 41 % yield. Although di-substituted porphyrin-HPBs 15 and 16 could
not be separated by chromatographic techniques, it was possible to isolate them individually by
crystallization. Single crystals, suitable for X-ray diffraction analysis (XRDA) of 15 (Figure 2) as well as
16 (Figure 3), were obtained from benzene/MeOH solutions and separated under the microscope.
However, the crystallization and separation of the two isomers 15 and 16 under the microscope is only
applicable to sub-milligram amounts and therefore not suitable for standard synthesis.
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Scheme 3. Mixed cyclotrimerization B: Two equivalents of 11 and one equivalent of 6 yielding six porphyrin-HPB products. Hexa-tert-
butyl-HPB 7 was formed only in minor quantities (< 1 mg) and therefore no yield was determined.
Single crystals, suitable for XRDA were obtained for all three di-substituted porphyrin-HPBs 8, 15, 16
as well as for tri-substituted porphyrin-HPB 14∙Ni3. The solvent system benzene/MeOH emerged as
the best medium for growing porphyrin-HPB single crystals since all structures presented herein were
obtained thereof. Crystals grown out of other solvent mixtures such as CH2Cl2/MeOH or
toluene/MeOH either lacked quality or were too small for successful measurements. Figure 1 depicts
the structure of the ortho isomer 8. The porphyrins are, due to their steric demand, tilted by about 37°
and 43° to the inner benzene ring (drawn in grey), respectively. In contrast to that, the porphyrins of
meta- and para-isomers 15, 16 (Figure 2 and 3) are in the same plane as the inner benzene ring
which results in an overall flat arrangement of these molecules in the solid state. The distance
between the porphyrin centers increases from 9.8 Å for ortho conjugate 8 to 21.3 Å for the para
conjugate 15. The crystal packing shows the formation of dimers of ortho-porphyrin-HPB 8, which are
rotated by 180° towards each other and stack via their HPB cores with a distance of 5.6 Å between the
central benzene rings. In the cases of meta- and para-conjugates 15 and 16, on the other hand,
molecules stack via a porphyrin and a HPB unit and form linear superstructures. The para-isomer 16
shows a dense packing motif with short intermolecular distances of 5.0 Å between the inner HPB
benzene rings. The packing motif of all conjugates is influenced by attractive interactions such as
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London dispersion33-34 and CH-p forces which are displayed exemplarily for ortho conjugate 8 in
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Figure 1 d).
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9.8 Å
d)
2.5 Å
2.9 Å
c)
2.4 Å
2.5 Å
5.6 Å
2.5 Å
Figure 1. a) Crystal structure of ortho-porphyrin-HPB 8. Co-crystallized benzene molecules were omitted for clarity; b), c)
packing of two molecules; hydrogen atoms and 3,5-di-tert-butylphenylene groups were omitted; d) packing of two molecules
with tert-butyl groups participating in CH-CH interactions as well as CH-p interactions being highlighted.
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c)
Figure 2. a) Structural motif of meta-porphyrin-HPB 15. Co-crystallized benzene molecules were omitted for clarity; b), c)
packing of three molecules; hydrogen atoms and 3,5-di-tert-butylphenylene groups were omitted. Due to the very small size of
the crystal and the large unit cell, the crystal diffracted weakly and only a substandard dataset could be obtained. For details
see supporting information.
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21.3 Å
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Figure 3. a) Crystal structure of para-porphyrin-HPB 16. Co-crystallized benzene molecules were omitted for clarity; b), c)
packing of three molecules; hydrogen atoms and 3,5-di-tert-butylphenylene groups were omitted.
Tri-substituted porphyrin-HPB 14 is special amongst all architectures presented here as it combines all
possible substitution patterns of the porphyrins (ortho, meta, para) within one molecule. A crystal
structure of tri-porphyrin-HPB 14 in its metalated form 14∙Ni3 (Figure 4) was obtained and showed
distorted porphyrin cores, resulting from the metal complexation of nickel. Compared to 8, the
porphyrins of the ortho motif in 14∙Ni3 are slightly more apart from each other with a center-to-center
distance of 10.2 Å. On the other hand, the torsion angles between the inner benzene ring and the
porphyrins is lower with values from 10 to 15°, which leads to an overall more flat arrangement of
14∙Ni3 compared to 8. However, free base porphyrins are compared with nickel-porphyrins and
therefore, the described differences in distances and torsion angels might be attributed to metalation
effects and not to the substitution pattern.
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18.3 Å
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10.2 Å
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5.9 Å
Figure 4. a) Structural motif of metalated tri-porphyrin-HPB 14∙Ni3. Co-crystallized benzene molecules were omitted for clarity;
b) side view of 14∙Ni3; c) packing of two molecules; b), c) hydrogen atoms and 3,5-di-tert-butylphenylene groups were omitted.
Due to the small size of the crystal and the large unit cell, the crystal diffracted weakly and only a substandard dataset could be
obtained. For details see supporting information.
UV/Vis absorption spectra were recorded for all compounds obtained purely and are divided into two
groups: Systems with all porphyrins being in close proximity to each other (8, 9, 10) and systems in
which some of the porphyrins are isolated (12, 13, 14). A comparison of the UV/Vis absorption spectra
of di-, tetra- and hexa-substituted porphyrin-HPBs 8, 9 and 10 (Figure 5) shows an increased molar
extinction coefficient for the absorption bands with respect to the number of porphyrins. However, the
increase is not linear as observed for the Soret-band absorptions (Table 1, Figure 5): in the series 8, 9
and 10, the more porphyrins are attached to the HPB core, the higher the molar extinction coefficient
per porphyrin. Similar behavior was observed for the Q-bands. The B-band of di-porphyrin-HPB 8 is
conspicuously broadened with respect to 9 and 10 (Figure 5b), displaying in a full width at half
maximum (FWHM) value of 17.5 nm. The occurrence of a broad absorption band has already been
described in the literature for a similar porphyrin dimer linked by a triphenylene bridge and was
attributed to strong through space interactions of the B states between the porphyrins.11-12 In our case
however, the distance between the chromophores of di-, tetra- and hexa-porphyrin HPBs 8, 9, 10 are
expected to be in the same order of magnitude and therefore, through space interactions are
anticipated to be similar. The only structural difference between di-, tetra- and hexa-porphyrin HPBs 8,
9, 10 is that more porphyrins hinder the rotational freedom. The crystal structure in Figure 1 shows,
that two porphyrins of 8 strongly affect each other. Still, there is enough room for motion/rotation. If the
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number of porphyrins is increased to four or six, a higher steric demand of the porphyrins results in a
more rigid structure with limited degree of internal movement. This might be one of the reasons for the
trend in this series of molecules (8, 9, 10) in which more porphyrins attached to the HPB give the
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narrower Soret-band. All compounds follow the Lambert-Beer law in a concentration range of 10-6
–
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10-8 M.
Table 1. Spectroscopic data for Soret-band absorptions.
Molecule
(Soret Band,
λ [nm])
FWHM
[nm]
휺
휺 per
[Lmol-
1cm-1]
porphyrin
[Lmol-1cm-1]
ref.-
porphyrin[a]
(419)
550 000
550 000
10.9
di-porphyrin 8
17.5
13.4
530 000
265 000
325 000
(419)
tetra-
porphyrin 9
(420)
1 300 000
hexa-
porphyrin 10
(420)
12.7
11.6
13.0
13.8
2 400 000
500 000
400 000
500 000
467 000
433 000
mono-
porphyrin 12
(419)
tri-porphyrin
13
1 400 000
1 300 000
(421)
tri-porphyrin
14
(420)
[a]tetrakis-(3,5-di-tert-butylphenyl)porphyrin was used as a reference compound.
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B-band
4E6
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2E6
2.0
8E6
1.8
8
Q-bands
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6E6
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.8E5
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0
350
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Wavelength [nm]
600
650
wavelength / nm
Figure 5. UV/Vis absorption spectra of porphyrin-HPBs 8, 9, 10 in THF. a) Complete spectra with magnified Q-band
absorptions; b) normalized B-band absorptions.
Figure 6 displays the UV/Vis spectra of the molecules with porphyrins more distant to each other.
Mono-porphyrin-HPB 12 has a slightly decreased molar extinction coefficient as well as a broadened
Soret-band compared to the reference compound tetrakis-(3,5-di-tert-butylphenyl)porphyrin.
Therefore, meso-substitution of one 3,5-di-tert-butylphenyl by a HPB moiety has a noticeable effect on
the electronic properties. A comparison of tri-substituted porphyrin-HPBs 13 ((AB)3) and 14 (A2B2AB)
shows a lower molar extinction coefficient and a broadened Soret-band for 14. Although 14 has the
same structural feature as di-porphyrin-HPB 8 (ortho-substitution of two porphyrins) and therefore was
anticipated to have similar properties to 8, the Soret-band of 14 is remarkably sharp with a FWHM
value of 13.8 nm. Consequently, the introduction of a third porphyrin has a significant impact on the
electronic properties. Due to the additional meta- and para-substitution motifs in 14, effects such as
electronic communication through bonds have to be considered. Porphyrin dimers, bridged via linear
triphenylene units, are known for their electronic communication through the bridge as para
substituted linkers are effective in elongating the p-conjugation pathway.35 Therefore, through bond as
well as through space communication might play a crucial role in the UV/Vis absorption characteristics
of 14 and the combination of both effects result in a relatively sharp Soret-band. System 13 on the
other hand, has only all meta substituted porphyrins in which neither through space nor through bond
interactions should be dominant. Yet, spectral differences between 13 and 14 are minor. Here, further
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photophysical measurements are required to understand the spectral properties of these porphyrin-
HPB systems. In general, mono- and tri-substituted HPBs 12, 13, and 14 having “isolated” porphyrins
feature higher molar extinction coefficients per porphyrin than di-, tetra- and hexa-conjugates 8, 9, 10.
Steady state fluorescence emission spectra were measured upon excitation of the porphyrins B-band
(Figure S6, S7). The fluorescence characteristics of porphyrin-HPBs vary only little compared to
reference compound tetrakis-(3,5-di-tert-butylphenyl)porphyrin. The emission intensities, however,
seem to be influenced by the number of porphyrins and the substitution pattern. Weaker fluorescence
intensities were found for systems with porphyrins in close proximity to each other. Detailed
photophysical experiments, including determination of fluorescence quantum yields, are currently
performed and will be reported elsewhere.
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B-band
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3E6
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2E6
1.1
1E6
12
1.0
1E6
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9E5
Q-bands
0.8
8E5
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7E5
0.6
6E5
0.5
5E5
0.4
4E5
0.3
3E5
0.2
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0.1
1E5
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400
450
500
550
Wavelength [nm]
600
650
wavelength / nm
Figure 6. UV/Vis absorption spectra of porphyrin-HPBs 12, 13, 14 in THF. a) Complete spectra with magnified Q-band
absorptions; b) normalized B-band absorptions.
Conclusions
We have shown the successful synthesis and isolation of six porphyrin-HPB conjugates by two mixed
cyclotrimerization reactions. Depending on the number and relative geometry of porphyrins per HPB,
different UV/Vis absorption characteristics were observed such as broadened Soret-band absorptions
and lowered molar extinction coefficients. Perturbed Soret states can be attributed to communication,
either through space or through bond, as well as to rotational freedom of the porphyrins. However, in
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order to understand the complex processes in more detail, we have started to perform time resolved
photophysical measurements. Solid state structures unveiled the relative geometry of porphyrins
towards the HPB core and showed overall flat arrangements. Unfortunately, the series of
ortho/meta/para-porphyrin-HPB isomers 8, 15, 16 could not be obtained separately, due to purification
difficulties. Yet, they are of great interest to further correlate the substitution pattern with their
properties. Therefore, selective strategies for the synthesis of these systems are currently under
investigation and will be reported elsewhere. The presented molecules are currently studied as
suitable precursors for the transformation to porphyrin-hexabenzocoronene conjugates.36-39
Additionally, these porphyrin-HPBs are expected to be capable of complexing several fullerenes,
similar to the systems of Gust et al.18 which is also currently analyzed.
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Experimental Section
All chemicals were purchased from Sigma-Aldrich and used without any further purification. Solvents
were distilled prior to usage. Dichloromethane was neutralized with K2CO3 before distillation. Thin
layer chromatography (TLC) was performed on Merck silica gel 60 F524, detected by UV-light
(254 nm, 366 nm). Column chromatography and flash column chromatography were performed on
Macherey-Nagel silica gel 60 M (deactivated, 230-400 mesh, 0.04 –0.063 mm). NMR spectroscopy
was performed on JEOL JNM EX 400 (1H: 400 MHz, 13C{1H}: 101 MHz), JEOL Alpha 500 (1H:
500 MHz, 13C{1H}: 126 MHz) and Bruker Avance 400 (1H: 400 MHz, 13C{1H}: 101 MHz). Deuterated
solvents were purchased from Sigma Aldrich and used as received. Chemical shifts are referenced to
residual protic impurities in the solvents (1H: CHCl3: 7.24 ppm) or the deuterated solvent itself (13C{1H}:
CDCl3: 77.0 ppm). The resonance multiplicities are indicated as “s“13 (singlet), “d” (doublet), “t”
(triplet), “q” (quartet) and “m” (multiplet). Signals referred to as “bs” (broad singlet) are not clearly
resolved or significantly broadened. IR spectra were recorded on a Bruker FT- IR Tensor 27
spectrometer with a Pike MIRacle ATR unit. LDI/MALDI-ToF mass spectrometry was performed either
on a Shimazu AXIMA Confidence or a Bruker Ultraflex Extreme machine. In case of MALDI, the
following matrix were used: 2,5-dihydroxybenzoic acid (DHB or trans-2-[3-(4-tert-butylphenyl)-2-
methyl-2-propenylidene]malononitrile (DCTB). High resolution mass spectrometry was performed on a
ESI/APPI-ToF mass spectrometer Bruker maXis 4G UHR MS/MS spectrometer, a Bruker micrOTOF II
focus TOF MS-spectrometer or on a MALDI-ToF Bruker Ultraflex Extreme spectrometer. X-ray
diffraction analysis was conducted on a Super Nova Dual Wavelength Platform diffractometer by
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Agilent Technologies GmbH. Microwave reactions were carried out in a mono-mode microwave
reactor Biotage Initiator+ with an external IR surface temperature sensor. The microwave assisted
reactions were carried out exclusively in the fixed hold time mode. UV/Vis spectroscopy was carried
out on a Varian Cary 5000 UV-Vis-NIR spectrometer. Unless otherwise noted, reactions were
degassed by the following technique: The reaction mixture was sonicated at 25 °C for 1 min under
vacuo, followed by a purge with N2-gas. This cycle was repeated three times.
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4-((4-(tert-butyl)phenyl)-ethynyl)benzaldehyde.
4-Bromobenzaldehyde
(3.00 g,
16.2 mmol,
1 equiv), Pd(PPh3)2Cl2 (227 mg, 0.32 mmol, 0.02 equiv) and CuI (31 mg, 0.16 mmol, 0.01 equiv) were
dissolved in THF (20 mL) and NEt3 (20 mL). The solution was degassed (3 x 1 min sonication under
vacuum followed by a purge of N2), 4-tert-butylphenylacetylene (3.06 mL, 2.69 g, 17.0 mmol,
1.05 equiv) was added via syringe and the mixture was degassed once more (1 x 1 min). The reaction
was heated to 75 °C for 19 h. The crude was purified by silica plug filtration (hexanes/CH2Cl2 – 1:1,
Ø 4.5 cm · 12 cm) followed by recrystallization from hot hexanes (100 mL, 65 °C). The pure product
was obtained as a beige solid in 85.8 % yield (3.65 g, 13.9 mmol). NMR and MS spectra were
identical to the ones reported in the literature.37, 40
General procedure for the synthesis of A3B porphyrins. Two 20 mL microwave vials were
prepared: Each vial was charged with a magnetic stir bar, CH2Cl2 (19 mL), aldehyde A (1.50 mmol,
3 equiv), aldehyde B (0.50 mmol, 1 equiv) and pyrrole (140 μl, 2.00 mmol, 4 equiv). A solution of I2
(25 mg, 0.10 mmol, 0.2 equiv) in CH2Cl2 (1.0 mL) was added to the particular vial, it was sealed with a
septum and heated in the microwave reactor (20 s pre-stirring, 5 min at 40 °C, max. power 100 W, for
exact conditions see SI). A flask charged with para-chloranil (736 mg, 3.00 mmol, 6 equiv) in 20 mL
CH2Cl2 was prepared and heated to reflux. After each microwave reaction had finished, the reaction
mixture was poured into the para-chloranil solution. After the content of the second vial was added to
the flask, the reaction mixture was stirred for further 15 min at reflux. The product mixture was
adsorbed on SiO2 (approx. 10 g) and separated via silica column chromatography (hexanes/CH2Cl2 –
3:1, Ø 6 cm · 37 cm). The second fraction was identified as the desired A3B products.
5-(4-Trimethylsilylethynyl-phenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrin 17.41-42 The
synthesis was recently reported43 and further improved by the above mentioned protocol. Aldehyde
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A:
3,5-di-tert-butylbenzaldehyde
(327 mg,
1.50 mmol),
aldehyde
B:
4-
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(trimethylsilylethynyl)benzaldehyde (101 mg, 0.50 mmol), yield: 14.8 % (155 mg, 148 μmol). H NMR
(400 MHz, CDCl3, rt): δ [ppm] = 8.90 – 8.87 (m, 6H), 8.79 (d, J = 4.8 Hz, 2H), 8.18 (d, J = 8.3 Hz, 2H),
8.06 - 8.05 (m, 6H), 7.86 (d, J = 8.3 Hz, 2H), 7.78 – 7.77 (m, 3H), 1.51 (s, 36H), 1.50 (s, 18H), 0.36 (s,
9H), -2.74 (s, 2H). 13C{1H} NMR (126 MHz, CDCl3, rt): δ [ppm] = 148.7, 142.9, 141.3, 141.2, 134.5,
134.2, 131.4, 130.4, 130.1, 129.9, 129.8, 129.6, 129.5, 122.4, 121.7, 121.5, 121.2, 120.9, 118.6,
105.2, 95.4, 35.0, 32.2, 31.9, 31.6, 31.3, 0.3, -0.1. IR: 휈 [cm-1] = 3318, 2954, 2160, 1593, 1476, 1362,
1247. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 419 (472000), 515 (19100), 550 (10500), 592 (5600), 648
(5000). MS (LDI): m/z (rel. int.) = 1046.86 (M+, 100 %).
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5-(4-Iodophenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrin 18.44 Aldehyde A: 3,5-di-tert-
butylbenzaldehyde (327 mg, 1.50 mmol), aldehyde B: 4-iodo-benzaldehyde (116 mg, 0.50 mmol,
1
yield: 15.1 % (162 mg, 151 μmol). H NMR (400 MHz, CDCl3, rt): δ [ppm] = 8.94 – 8.91 (m, 6H), 8.84
(d, J = 4.8 Hz, 2H), 8.11 - 8.08 (m, 8H), 7.99 (d, J = 8.3 Hz, 2H), 7.82 - 7.80 (m, 3H), 1.54 (s, 36H),
1.53 (s, 18H), -2.70 (s, 2H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 148.83, 148.78, 142.2,
141.3, 141.2, 136.2, 135.8, 131.5, 129.9, 129.8, 121.8, 121.6, 121.1, 117.9, 94.0, 35.0, 31.7. IR: 휈
[cm-1] = 3316, 2961, 1592, 1474, 1362, 1246, 1007. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 419 (507000),
515 (19200), 550 (9900), 591 (5400), 648 (4500). MS (LDI): m/z (rel. int.) = 1077 (M+, 100 %). HRMS
(APPI, toluene) for C68H77IN4 (M+), calc.: 1076.5187, found: 1076.5181.
Free base tolan-porphyrin 19. Aldehyde A: 3,5-di-tert-butylbenz-aldehyde (327 mg, 1.50 mmol),
aldehyde B: 4-((4-(tert-butyl)phenyl)-ethynyl)benzaldehyde (144 mg, 0.55 mmol), yield: 13.5 %
(150 mg, 135 μmol). 1H NMR (400 MHz, CDCl3, rt): δ [ppm] = 8.91 (d, J = 4.3 Hz, 6H), 8.86 (d, J = 4.6
Hz, 2H), 8.23 (d, J = 8.1 Hz, 2H), 8.12 – 8.05 (m, 6H), 7.92 (d, J = 7.9 Hz, 2H), 7.83 – 7.76 (m, 3H),
7.62 (d, J = 8.1 Hz, 2H), 7.45 (d, J = 8.3 Hz, 2H), 1.53 (s, 36H), 1.52 (s, 18H), 1.38 (s, 9H), -2.68 (s,
2H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 151.8, 148.79, 148.75, 142.5, 141.4, 141.3, 134.6,
131.6, 130.0, 129.9, 129.8, 125.5, 122.9, 121.7, 121.5, 121.1, 120.3, 118.8, 90.6, 88.8, 35.0, 34.8,
31.7, 31.2. IR: 휈 [cm-1] = 3313, 2963, 1590, 1474, 1362, 1247. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 420
(546000), 516 (20600), 550 (12100), 591 (6300), 648 (6100). MS (LDI): m/z (rel. int.) = 1106.63 (M+,
100 %). HRMS (APPI, toluene) for C80H90N4 (M+), calc.: 1106.7160, found: 1106.7164.
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General procedure for the synthesis of nickel porphyrins. Free base porphyrin (1 equiv), Ni(acac)2
(5 equiv) were dissolved in toluene and heated to reflux for 90 min. The solvent was removed and the
product purified by silica plug filtration (hexanes/CH2Cl2 – 1:1). The product could be obtained as a
red-orange solid.
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Nickel-trimethylsilylethynyl-porphyrin 20. Free base trimethylsilyl-ethynyl-porphyrin 17 (129 mg,
123 μmol, 1 equiv), Ni(acac)2 (154 mg, 599 μmol, 5 equiv), toluene (25 mL), yield 100 % (136 mg,
1
123 μmol). H NMR (400 MHz, CDCl3, rt): δ [ppm] = 8.79 (bs, 4H), 8.76 (d, J = 4.9 Hz, 2H), 8.67 (d,
J = 5.0 Hz, 2H), 7.95 (d, J = 8.3 Hz, 2H), 7.85 (d, J = 1.8 Hz, 6H), 7.77 (d, J = 8.3 Hz, 2H), 7.71 – 7.67
(m, 3H), 1.45 (s, 36H), 1.45 (s, 18H), 0.34 (s, 9H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 149.0,
142.92, 142.85, 142.2, 141.6, 140.0, 133.6, 132.6, 132.5, 132.4, 131.5, 131.3, 131.1, 130.5, 130.2,
128.8, 128.7, 127.3, 122.5, 121.2, 120.4, 120.3, 117.6, 105.1, 95.3, 34.9, 31.6, -0.1. IR: 휈 [cm-1] =
2953, 2160, 1592, 1362, 1247, 1006. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 415 (217000), 527 (17900).
MS (LDI): m/z (rel. int.) = 1103 (M+, 100 %). HRMS (APPI, CH2Cl2) for C73H84N4NiSi (M+), calc.:
1102.5813, found: 1102.5828.
Nickel-iodo-porphyrin 21. Free base iodo-porphyrin 18 (253 mg, 235 μmol, 1 equiv), Ni(acac)2
(295 mg, 1.15 mmol, 5 equiv), toluene (50 mL), yield: 97.9 % (261 mg, 230 μmol). 1H NMR (400 MHz,
CDCl3, rt): δ [ppm] = 8.83 – 8.76 (m, 6H), 8.71 (d, J = 4.9 Hz, 2H), 8.01 (d, J = 8.1 Hz, 2H), 7.91 – 7.83
(m, 6H), 7.77 (d, J = 8.0 Hz, 2H), 7.74 – 7.70 (m, 3H), 1.47 (s, 36H), 1.47 (s, 18H). 13C{1H} NMR
(101 MHz, CDCl3, rt): δ [ppm] = 149.02, 148.99, 142.94, 142.87, 142.85, 142.1, 140.8, 139.95, 139.93,
136.0, 135.4, 132.7, 132.54, 132.45, 131.5, 128.9, 128.7, 121.2, 120.4, 120.3, 117.0, 93.9, 34.92,
34.92, 31.6. IR: 휈 [cm-1] = 2960, 1593, 1362, 1247, 1003. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 415
(274000), 527 (19500). MS (LDI): m/z (rel. int.) = 1132.52 (M+, 100 %). HRMS (APPI, toluene) for
C68H75IN4Ni (M+), calc.: 1132.4384, found: 1132.4385.
Nickel-tolan-porphyrin 11. Free base tolan-porphyrin 19 (270 mg, 0.244 mmol, 1 equiv), Ni(acac)2
(313 mg, 1.22 mmol, 5 equiv), toluene (50 mL) yield: 99.6 % (283 mg, 0.243 mmol). 1H NMR
(400 MHz, CDCl3, rt): δ [ppm] = 8.81 – 8.78 (m, 6H), 8.74 (d, J = 4.9 Hz, 2H), 8.01 (d, J = 8.2 Hz, 2H),
7.88 – 7.85 (m, 6H), 7.83 (d, J = 8.2 Hz, 2H), 7.73 – 7.69 (m, 3H), 7.58 (d, J = 8.5 Hz, 2H), 7.43 (d, J =
8.6 Hz, 2H), 1.46 (s, 36H), 1.46 (s, 18H), 1.36 (s, 9H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] =
151.7, 148.93, 148.91, 142.85, 142.80, 142.78, 142.2, 141.1, 140.0, 133.7, 132.6, 132.4, 132.3, 131.6,
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131.5, 130.1, 128.8, 128.7, 125.5, 122.9, 121.1, 120.3, 120.2, 117.8, 90.5, 88.8, 35.0, 34.9, 31.7, 31.2.
IR: 휈 [cm-1] = 2953, 1591, 1362, 1352, 1247, 1001. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 416 (294000),
528 (21300). MS (MALDI, DHB): m/z (rel. int.) = 1162.58 (M+, 100 %). HRMS (APPI, toluene) for
C80H88N4Ni (M+), calc.: 1162.6357, found: 1162.6373.
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Nickel-ethynyl-porphyrin 22. Trimethylsilyl-protected nickel-porphyrin 20 (137 mg, 124 μmol,
1 equiv) was dissolved in THF (15 mL), a 1 M TBAF solution in THF (300 μL, 300 μmol, 2.4 equiv)
was added and the reaction was stirred light protected for 90 min at rt. The solvent was removed and
the porphyrin was purified by plug filtration (SiO2, hexanes/CH2Cl2 – 4:1). The product could be
1
obtained in 78.1 % yield (100 mg, 96.9 μmol). H NMR (500 MHz, CDCl3, rt): δ [ppm] = 8.81 (s, 4H),
8.79 (d, J = 4.9 Hz, 2H), 8.70 (d, J = 4.9 Hz, 2H), 7.99 (d, J = 8.3 Hz, 2H), 7.88 – 7.86 (m, 6H), 7.80 (d,
J = 8.1 Hz, 2H), 7.73 – 7.70 (m, 3H), 3.26 (s, 1H), 1.47 (s, 36H), 1.46 (s, 18H). 13C{1H} NMR
(101 MHz, CDCl3, rt): δ [ppm] = 149.03, 149.01, 143.0, 142.9, 142.2, 141.9, 140.0, 133.7, 132.7,
132.5, 132.4, 131.6, 130.7, 128.8, 128.7, 121.5, 121.2, 120.4, 120.3, 117.5, 83.7, 78.1, 34.9, 31.6. IR:
휈 [cm-1] = 3294, 2958, 1592, 1361, 1247, 1006. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 415 (237000), 527
(17400). MS (LDI): m/z (rel. int.) = 1030.52 (M+, 100 %). HRMS (APPI, toluene) for C70H76N4Ni (M+),
calc.: 1030.5418, found: 1030.5414.
Nickel-porphyrin dimer 5.11 A 20 mL vial was charged with nickel-iodo-porphyrin 21 (95.5 mg,
84.3 μmol, 1 equiv), Pd(PPh3)2Cl2 (3.0 mg, 4.3 μmol, 0.05 equiv), CuI (1.6 mg, 8.4 μmol, 0.1 equiv),
NEt3 (2.5 mL) and THF (2.5 mL). The vial was sealed with a septum, the mixture degassed and stirred
for 10 min at rt before a degassed solution of nickel-ethynyl-porphyrin 22 (100 mg, 96.9 μmol,
1.15 equiv) in THF (2.5 mL) was added via syringe through the septum. The reaction was heated to
50 °C for 20 h under the exclusion of light. The solvent was removed and the crude purified by column
chromatography (SiO2, hexanes/CH2Cl2 – 4:1). The product could be obtained as a red solid in 95.5 %
yield (164 mg, 80.5 μmol). 1H NMR (400 MHz, CDCl3, rt): δ [ppm] = 8.86 – 8.75 (m, 16H), 8.09 (d, J =
7.8 Hz, 4H), 7.96 (d, J = 7.9 Hz, 4H), 7.91 – 7.86 (m, 12H), 7.74 – 7.70 (m, 6H), 1.48 (s, 72H), 1.47 (s,
36H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 148.97, 148.94, 142.89, 142.83, 142.82, 142.2,
142.0, 141.5, 140.0, 133.8, 132.6, 132.44, 132.35, 131.6, 130.2, 128.8, 128.7, 122.7, 121.1, 120.4,
120.3, 117.7, 90.4, 35.0, 31.7. IR: 휈 [cm-1] = 2961, 1593, 1362, 1298, 1247, 1007. UV/Vis (THF): λ
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[nm] (ε [M-1cm-1]) = 418 (553000), 528 (44600). MS (MALDI, DCTB): m/z (rel. int.) = 2036.24 (M+,
100 %). HRMS (APPI, toluene) for C138H150N8Ni2 (M+), calc.: 2038.0708, found: 2038.0767.
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Mixed cyclotrimerization A. A 5 mL vial was charged with porphyrin-dimer 5 (67 mg, 32.9 µmol,
2 equiv), tert-butyl-tolane 632 (4.8 mg, 16.4 µmol, 1 equiv), Co2(CO)8 (12.5 mg, 37.0 µmol, 2.25 equiv),
toluene (2.5 mL) and sealed with a septum. The solution was degassed (bubbling N2 through solution
for 15 min) and heated to 140 °C for 16 h with an oil bath. After silica plug filtration (hexanes/CH2Cl2 –
2:1, Ø 3.5 cm · 10 cm), the product mixture was dissolved in CH2Cl2 (5 mL), cooled with an ice bath
and conc. H2SO4 (0.5 mL) was added. The reaction was stirred for 60 min at 0 °C before the acid was
slowly quenched via the addition of NEt3 (5 mL). The mixture was immediately poured over a plug of
silica (hexanes/CH2Cl2 – 1:1, Ø 3.5 cm · 9 cm). After removing the solvent, free base porphyrins were
separated by size exclusion chromatography (Bio Beads SX1, toluene, Ø 4.5 cm · 50 cm) and silica
column chromatography (hexanes/CH2Cl2 – 2:1, Ø 5 cm · 32 cm). Yields: Di-porphyrin-HPB 8: 12.2%
(5.0 mg, 2.00 µmol). Tetra-porphyrin-HPB 9: 39.3 % (26.7 mg, 6.45 µmol). Hexa-porphyrin-HPB 10:
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11.4 % (10.8 mg, 1.87 µmol). Di-porphyrin-HPB 8. H NMR (400 MHz, CDCl3, rt): δ [ppm] 8.90 (d,
J = 4.4 Hz, 2H), 8.87 (d, J = 4.3 Hz, 2H), 8.80 (d, J = 4.6 Hz, 2H), 8.73 (d, J = 4.6 Hz, 2H), 8.57 (m,
6H), 8.08 (s, 4H), 8.04 (d, J = 1.8 Hz, 4H), 7.93 (d, J = 8.1 Hz, 4H), 7.88 (d, J = 4.6 Hz, 2H), 7.80 (s,
2H), 7.75 (t, J = 1.9 Hz, 2H), 7.46 (d, J = 8.1 Hz, 4H), 7.41 (s, 4H), 7.17 – 7.10 (m, 8H), 7.00 – 6.89
(m, 8H), 1.54 (s, 36H), 1.51 (s, 36H), 1.50 (s, 36H), 1.19 (s, 18H), 1.17 (s, 18H), 0.56 (s, 36H), -2.82
(s, 4H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 157.3, 148.8, 148.7, 148.3, 147.9, 147.8, 141.6,
141.4, 141.2, 141.1, 140.8, 140.6, 140.4, 139.6, 138.2, 137.9, 132.7, 131.7, 131.3, 131.1, 130.2,
130.1, 129.84, 129.79, 129.7, 129.0, 127.3, 123.6, 123.4, 123.3, 121.10, 121.06, 120.9, 120.3, 119.8,
118.9, 35.01, 34.97, 34.2, 34.1, 34.0, 31.7, 31.3, 31.2, 30.8. IR: 휈 [cm-1] = 2960, 1592, 1475, 1362,
1247. UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 419 (534000), 515 (28500), 550 (13700), 592 (7700),
648 (6400). Fluorescence (THF, λexc. = 419 nm): λemission [nm] (rel. int.) = 651 (1.00), 716 (0.24). MS
(MALDI): m/z (rel. int.) = 2505.64 (M+, 100 %). HRMS (APPI, toluene) for C182H206N8 (M+), calc.:
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2505.6427, found: 2505.6447. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.52. Tetra-porphyrin-HPB 9. H
NMR (500 MHz, CDCl3, RT): δ [ppm] = 9.08 – 8.60 (m), 8.55 (s), 8.37 (d, J = 7.5 Hz), 8.29 – 7.95 (m),
7.88 (s), 7.86 – 7.70 (m), 7.65 (s), 7.54 (s), 7.42 (d, J = 7.8 Hz), 7.37 (d, J = 7.9 Hz), 7.34 (s), 7.21 (s),
7.11 (s), 6.83 (s), 1.62 (s), 1.57 (s), 1.53 (s), 1.34 (s), 1.28 (s), 0.84 (s), 0.76 (s), 0.48 (s), -2.80 (s).
13C{1H} NMR (126 MHz, CDCl3, RT): δ [ppm] = 148.8, 148.7, 148.6, 148.1, 148.0, 147.9, 147.7, 141.8,
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141.7, 141.5, 141.43, 141.40, 141.1, 140.92, 140.87, 140.8, 140.6, 140.50, 140.47, 139.8, 138.2,
133.5, 132.7, 131.8, 130.7, 130.2, 129.8, 129.7, 129.2, 129.1, 128.8, 123.9, 121.1, 121.03, 120.95,
120.88, 120.4, 120.1, 119.61, 119.58, 35.1, 35.0, 34.4, 34.3, 34.2, 33.9, 31.8, 31.73, 31.70, 31.4,
31.03, 30.98, 30.7, 29.7. IR: 휈 [cm-1] = 2961, 1592, 1475, 1362, 1247. UV/Vis (THF): λ [nm] (ε [M-1cm-
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1]) = 420 (1270000), 515 (59300), 549 (27200), 591 (16000), 648 (12700). Fluorescence (THF, λexc.
=
419 nm): λemission [nm] (rel. int.) = 651 (1.00), 717 (0.22). HRMS (APPI, toluene) for C298H334N16 (M+),
calc.: 4140.6799, found: 4140.6961. HRMS (MALDI, DCTB) for C298H334N16 (M+), calc.: 4140.6799,
found: 4140.6904. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.52. Hexa-porphyrin-HPB 10. 1H NMR
(500 MHz, CDCl3, rt): δ [ppm] = 8.76 (d, J = 4.7 Hz, 12H), 8.70 (d, J = 4.7 Hz, 12H), 8.60 (d, J =
4.8 Hz, 12H), 8.45 (d, J = 7.5 Hz, 12H), 8.23 (d, J = 7.6 Hz, 12H), 8.06 (d, J = 1.6 Hz, 12H), 7.97 (d,
J = 4.7 Hz, 12H), 7.78 (t, J = 1.7 Hz, 6H), 7.48 (very broad signal, 24H), 7.04 (s, 12H), 1.53 (s, 108H),
1.42 – -0.30 (very broad signal, 216H), -2.86 (s, 12H). 13C{1H} NMR (126 MHz, CDCl3, rt): δ [ppm] =
148.6, 147.9, 141.74, 141.69, 140.9, 140.8, 133.5, 130.8, 129.6, 128.9, 128.7, 121.0, 120.8, 120.3,
119.4, 35.0, 34.1 (bs), 31.8, 30.9 (bs). IR: 휈 [cm-1] = 3318, 2961, 1592, 1475, 1363, 1246. UV/Vis
(THF): λ [nm] (ε [M-1cm-1]) = 420 (2400000), 515 (104000), 549 (48000), 591 (29500), 647 (22400).
Fluorescence (THF, λexc. = 419 nm): λemission [nm] (rel. int.) = 651 (1.00), 717 (0.25). MS (MALDI,
DCTB): m/z (rel. int.) = 5774.12 (M+, 100 %). HRMS (ESI, CH3CN/toluene/formic acid) for C414H462N24
(MH22+), calc.: 2887.8583, found: 2887.8516. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.71.
Mixed cyclotrimerization B. A 5 mL vial was charged with nickel-tolan-porphyrin 11 (283 mg,
243 µmol, 2 equiv), tert-butyl-tolane 632 (35 mg, 122 µmol, 1 equiv), Co2(CO)8 (12.5 mg, 36.5 µmol,
0.30 equiv), toluene (2.5 mL) and sealed with a septum. The reaction mixture was degassed (bubbling
N2 through the solution for 15 min) and heated with an oil bath to 140 °C for 16 h. The solvent was
removed and the crude was purified by silica plug filtration (hexanes/CH2Cl2 1:1). The mixture was
dissolved in CH2Cl2 (30 mL) and cooled with an ice bath. Conc. H2SO4 (3 mL) was added and the
reaction was stirred for 60 min. The acid was quenched via the addition of NEt3 (30 mL) and the
mixture was immediately poured on a plug (SiO2, hexanes/CH2Cl2 – 3:1, Æ 13 cm ∙ 8 cm). Note: For
reactions on this scale it is probably better to quench the acid via washing with water (3x) and sat.
NaHCO3 (1x).17 With the help of column chromatography (SiO2, hexanes/CH2Cl2
– 3:1,
Æ 7 cm ∙ 32 cm) and size exclusion chromatography (bio beads SX1, THF, Æ 3.5 cm ∙ 30 cm) four of
the six porphyrin products were separated from each other. Only the meta- and para-porphyrin-HPBs
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15, 16 could not be separated with these purification techniques. Yields: Mono 12 (8.4 mg, 4.95 µmol,
4.1 %), ortho 8 (25.6 mg, 10.2 µmol, 8.4 %), meta/para mixture 15, 16 (101.6 mg, 40.55 µmol,
33.3 %), (AB)3 13 (10.5 mg, 3.16 µmol, 2.6 %), A2B2AB 14 (53.2 mg, 16.01 µmol, 13.2 %). Mono-
porphyrin-HPB 12.39 1H NMR (400 MHz, CDCl3, rt): δ [ppm] = 8.91 (d, J = 4.8 Hz, 2H), 8.87 (d, J =
4.8 Hz, 2H), 8.71 (d, J = 4.8 Hz, 2H), 8.45 (d, J = 4.7 Hz, 2H), 8.05 (d, J = 1.7 Hz, 6H), 7.78 (t, J = 1.8
Hz, 2H), 7.77 (t, J = 1.8 Hz, 1H), 7.69 (d, J = 8.0 Hz, 2H), 7.19 (d, J = 8.1 Hz, 2H), 7.14 (d, J = 8.4 Hz,
4H), 7.01 (d, J = 8.3 Hz, 4H), 6.93 – 6.78 (m, 12H), 1.52 (s, 36H), 1.50 (s, 18H), 1.32 (s, 18H), 1.15 (s,
18H), 1.14 (s, 9H), -2.80 (s, 2H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 148.74, 148.68, 148.1,
147.7, 147.6, 141.5, 141.2, 141.1, 140.9, 140.6, 140.44, 140.39, 138.7, 138.2, 137.98, 137.93, 132.7,
131.6, 131.3, 131.2, 130.0, 129.8, 129.7, 123.5, 123.24, 123.21, 121.22, 121.20, 120.9, 120.1, 34.96,
34.95, 34.3, 34.1, 34.0, 31.7, 31.4, 31.2. IR: 휈 [cm-1] = 2955, 1591, 1475, 1393, 1362, 1247. UV/Vis
(THF): λ [nm] (ε [M-1cm-1]) = 419 (503000), 516 (18900), 551 (10900), 593 (5530), 648 (5130).
Fluorescence (THF, λexc. = 419 nm): λemission [nm] (rel. int.) = 653 (1.00), 718 (0.21). MS (LDI): m/z (rel.
int.) = 1687.12 (M+, 100 %). HRMS (APPI, toluene) for C124H142N4 (M+), calc.: 1688.1262, found:
1688.1281. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.56. Ortho-di-porphyrin-HPB 8. Same data observed
as in mixed cyclotrimerization A. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.56. Meta/para-di-porphyrin-HPB
mixture 15, 16. MS (LDI): m/z (rel. int.) = 2504.38 (M+, 100 %). HRMS (APPI, toluene) for C182H206N8
(M+), calc.: 2505.6426, found: 2505.6502. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.46. (AB)3-tri-porphyrin-
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HPB 13. H NMR (400 MHz, CDCl3, rt): δ [ppm] = 8.98 (d, J = 4.7 Hz, 6H), 8.94 (d, J = 4.3 Hz, 6H),
8.85 (d, J = 4.5 Hz, 6H), 8.62 (d, J = 4.3 Hz, 6H), 8.15 (d, J = 1.9 Hz, 12H), 8.11 (d, J = 1.9 Hz, 6H),
7.92 (d, J = 8.0 Hz, 6H), 7.88 (d, J = 1.8 Hz, 6H), 7.82 (d, J = 1.8 Hz, 3H), 7.60 – 7.46 (m, 18H), 1.61
(s, 135H), 1.55 (s, 54H), -2.69 (s, 6H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 149.0, 148.84,
148.75, 141.5, 141.3, 141.1, 140.92, 140.86, 139.2, 138.4, 133.1, 132.1, 130.1, 130.0, 129.8, 124.1,
121.3, 121.0, 120.0, 35.04, 35.00, 34.7, 31.8, 31.7. IR: 휈 [cm-1] = 2954, 1592, 1475, 1393, 1362, 1246.
UV/Vis (THF): λ [nm] (ε [M-1cm-1]) = 421 (1350000), 516 (57200), 550 (33400), 593 (18500), 648
(16800). Fluorescence (THF, λexc. = 419 nm): λemission [nm] (rel. int.) = 652 (1.00), 717 (0.21). MS
(MALDI, DHB): m/z (rel. int.) = 3320.21 (M+, 100 %). HRMS (ESI, CH3CN) for C240H270N12 (M2+), calc.:
1662.0854, found: 1662.0841. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.36. A2B2AB-tri-porphyrin-HPB 14.
1H NMR (400 MHz, CDCl3, rt): δ [ppm] = δ 8.98 – 8.57 (m, 24H), 8.20 – 8.02 (m), 7.96 (s), 7.89 – 7.76
(m), 7.67 – 7.58 (m), 7.54 – 7.43 (m), 7.41 – 7.27 (m), 7.06 – 6.93 (m), 1.66 – 1.46 (m), 1.42 (s), 0.62
(s), -2.73 (s, 2H), -2.77 (s, 4H). 13C{1H} NMR (101 MHz, CDCl3, rt): δ [ppm] = 157.3, 148.74, 148.66,
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148.61, 148.51, 148.45, 147.9, 141.6, 141.5, 141.2, 140.9, 140.6, 139.7, 139.1, 138.4, 138.1, 133.0,
132.8, 132.1, 131.7, 131.3, 131.1, 130.1, 129.9, 129.73, 129.73, 129.65, 129.0, 127.2, 124.0, 123.8,
123.2, 121.3, 121.11, 121.07, 120.9, 120.0, 119.7, 118.9, 35.11, 35.08, 35.05, 34.6, 34.5, 34.4, 34.1,
31.82, 31.77, 31.7, 31.6, 31.4, 30.9. IR: 휈 [cm-1] = 2960, 1591, 1474, 1362, 1246. UV/Vis (THF): λ [nm]
(ε [M-1cm-1]) = 420 (1310000), 515 (58200), 549 (30200), 591 (17400), 648 (15000). Fluorescence
(THF, λexc. = 419 nm): λemission [nm] (rel. int.) = 652 (1.00), 717 (0.23). MS (LDI): m/z (rel. int.) =
3321.09 (M+, 100 %). HRMS (ESI, CH3CN/toluene) for C240H270N12 (M2+), calc.: 1662.0854, found:
1662.0861. Rf (hexanes/CH2Cl2 – 2:1) [%] = 0.50.
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Supporting information
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Additional synthetic schemes, exact reaction conditions for microwave reactions, UV/Vis, H, 13C{1H}
spectra and crystallographic details for all crystal structures.
Author information
Corresponding Author
*norbert.jux@fau.de
ORCID
Norbert Jux: https://orcid.org/0000-0002-5673-8181
Max M. Martin: https://orcid.org/0000-0001-6523-9344
Jens Langer: https://orcid.org/0000-0002-2895-4979
Notes
The authors declare no competing financial interest.
Acknowledgements
We gratefully acknowledge the funding by the German Research Council (DFG) through the
Collaborative Research Centre SFB 953 (Synthetic Carbon Allotropes). M. M. M. thanks the German
Fond der Chemischen Industrie (FCI) as well as the Graduate School Molecular Science (GSMS) for
financial support.
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