Geodesic-Planar Conjugates: Substituted Buckybowls—Synthesis, Photoluminescence and Electrochemistry

Article abstract of DOI:10.1002/chem.202003605

C?C cross coupling products of bowl-shaped as-indaceno[3,2,1,8,7,6-pqrstuv]picene (Idpc) and different planar arenes and ethynyl-arenes were synthesized. Photoluminescence as well as electrochemical properties of all products were investigated and complemented by time-dependent quantum chemical calculations. UV/Vis spectroelectrochemistry investigations of the directly linked (Idpc)₂ indicated the absence of any intramolecular charge-transfer transition of intermittently formed (Idpc)₂^.?. All coupling products showed fluorescence. Ferrocene-1-yl-Idpc was structurally characterized by X-ray diffraction and is a rare example of a ferrocene-containing buckybowl exhibiting luminescence.

Full text of DOI:10.1002/chem.202003605

Accepted Article
Accepted Article
Title: Geodesic–Planar Conjugates: Substituted Buckybowls –
Synthesis, Photoluminescence and Electrochemistry
Authors: Johannes Bayer, Jan Herberger, Lukas Holz, Rainer Winter,
and Thomas Huhn
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To be cited as: Chem. Eur. J. 10.1002/chem.202003605
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01/2020

10.1002/chem.202003605
Chemistry - A European Journal
Geodesic–Planar Conjugates: Substituted Buckybowls – Synthesis,
Photoluminescence and Electrochemistry
Johannes Bayer‡, Jan Herberger‡, Lukas Holz, Rainer Winter and Thomas Huhn*[a]
[a] J. Bayer, J. Herberger, L. Holz, Prof. Dr. R. Winter and Dr. T. Huhn
Fachbereich Chemie, Universität Konstanz, Universitätsstr. 10, D-78457 Konstanz, Germany
Tel: (+49)7531 - 88 2283; Fax: (+49) 7531-884424
*E-mail: thomas.huhn@uni-konstanz.de
‡ Equal contribution
Abstract
C–C Cross coupling products of bowl-shaped as-indaceno[3,2,1,8,7,6-pqrstuv]picene (Idpc) and
different planar arenes and ethynyl-arenes were synthesized. Photoluminescence as well as
electrochemical properties of all products were investigated and complemented by time-dependent
quantum chemical calculations. UV/vis- spectroelectrochemistry investigations of the directly linked
(Idpc)2 uncovered the formation of 65 % (Idpc–)2 as the major reduction product. All coupling
products showed fluorescence. Ferrocene-1-yl-Idpc was structurally characterized by X-ray diffraction
and is a rare example of a ferrocene-containing buckybowl exhibiting luminescence.
Introduction
Indacenopicene (Idpc) is one member of the interesting class of condensed polyarenes with a non-
planar -surface. The curvature of these open geodesic molecules results from substituting some of the
six-membered rings within their poly-benzenoid network by five-membered ones. Some of these bowl-
shape molecules can be mapped on the surface of buckminsterfullerene, hence they are often named
“bucky-bowls”. Corannulene (CA) as the most studied member of this class of compounds was already
synthesized in 1966.[1]
The non-planarity of geodesic arenes, such as CA, benzocorannulene or indenocorannulene, imposes
novel physical properties[2-5] and chemical reactivity,[6-7] which sets them apart from planar polycyclic
aromatic hydrocarbons (PAHs). The most distinct feature is the inherent presence of a dipole moment,
thus allowing formation of dipolar structures in the solid state.[8] As a direct consequence of the
pyramidalization of carbon atoms, the -bonds are weakened, i.e. LUMO is lowered and HOMO is
raised in energy, approaching towards the state without conjugation. A second aspect to consider is the
mixing of s-orbital character with the p-orbital of the  -bond, thus lowering the energy of both, the
1
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HOMO and the LUMO. As a net effect the HOMO energy remains virtually unchanged while the
LUMO is substantially lowered in energy.[9] Therefore, these molecules can be easily reduced offering
potential applications in electron storage and electroluminescence applications.[10-11]
During the last decades the chemistry and physics of CA-derived bucky-bowl derivatives was
thoroughly studied.[12-18] However, comparably less work has been carried out in the field of Idpc and
its derivatives. The first synthetic approach towards Idpc by palladium catalyzed cyclization of suitable
precursors was reported already in 2000 but lacked generality.[19] The aluminium-oxide mediated
cove-region ring-closure through C–F bond activation of fluoroarenes[20] towards pristine Idpc and
other bowl-shape PAHs developed by Amsharov et al. in 2012 constituted a major breakthrough.[21]
A
comparative study of the fundamental aromaticity and electrochemistry of unsubstituted Idpc and CA
revealed a lower delocalization of electrons in Idpc compared to other PAHs as a direct result of the
nonequivalence of the five six-membered rings. The low LUMO energy and the smaller HOMO–
LUMO gap compared to CA, render Idpc a particularly interesting -acceptor for organic
electronics.[22] Bromine atoms at the periphery of an Idpc precursor were recently shown to be
tolerated by the aluminum-oxide ring-closing methodology, but no C–C coupling reactions on Idpc
were reported yet.[23]
The present study aimed at exploring the scope of Idpc-Br functionalization by cross-coupling
reactions with a panel of differently substituted phenyl boronates as well as phenyl acetylenes, both
electron-rich and electron-deficient. Electronic absorption spectra as well as fluorescence emission
spectra and cyclic voltammograms of the resulting bowl-shaped Idpc–arene and Idpc–ethynyl-arene
hybrid materials were obtained. The results of these studies are discussed together with those of
accompanying quantum chemical calculations on the DFT-level.
Results and Discussion
Synthesis and solid state structure
1-Bromoindacenopicene (Idpc-Br) served as the common starting material for all Suzuki and
Sonogashira coupling reactions towards Idpc–(ethynyl)arene hybrid materials. Idpc-Br was
synthesized by thermal aluminum oxide promoted dehydrofluorination of neat 4-bromo-13,16-
difluorobenzo[s]picene (4) at 280 °C in a sealed tube.[23] The above picene 4 is accessible from a
sequence of two consecutive Wittig and oxidative photocyclization reactions starting from 2,5-
difluorobenzyl bromide (1) (Scheme 1). An E/Z-mixture of stilbene 2 obtained from the Wittig
reaction of 2-acetonaphthone was subjected to a Mallory photocyclization[24] to afford 1,4-difluoro-6-
methylbenzo[c]phenanthrene (3), a substituted [4]helicene. Single crystals suitable for an X-ray
diffraction study could be grown by slow evaporation of a saturated solution of phenanthrene 3 in
2
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dichloromethane. 3 crystallizes in the monoclinic space group P21/n with a single molecule forming
the asymmetric unit. The unit cell consists of four molecules with no additional solvent. The structure
is best characterized as helically–bent with an angle of 26.67° between the two planes described by the
10 atoms of each naphthalene subunit. The torsion angles C1–C18–C17–C16 and C15–C16–C17–C18
of 27.19° and 21.08° at the inner helical rim are much larger than in the parent [4]helicene [CSD code:
BZPHAN] (17.11° and 20.16°), as is the dihedral angle of 37.45° between both terminal benzene rings
when compared to that of 27.26° for [4]helicene (Scheme 1). Both naphthalene subunits in 3 are
themselves severely bent from planarity as a result of the strong steric repulsion between the C1–F and
the C15–H atoms which are only 2.297 Å apart. A further consequence of the difluoro substitution
pattern is found in the packing of the difluoro [4]helicene 3 in the solid state. It adopts a partial face-to-
face arrangement of the fluorine-rich parts of the molecules with alternating layers of the individual
enantiomers (Figure S4/S5) and alternating interlayer distances of 3.381 Å and 3.610 Å. This contrasts
to the solid structure of [4]helicene, which is characterized by the archetypical herringbone edge-to-
face arrangement.[25] The synthesis of the planar bucky-bowl precursor 4-bromo-13,16-
difluorobenzo[s]picene (4) of Idpc-Br was then completed by a sequence of benzylic bromination,
Wittig reaction with 2-bromobenzaldehyde and a second Mallory photocyclization.
Scheme 1. Synthesis of 1-bromoindacenopicene (Idpc-Br); inset shows ORTEP of precursor 1,4-
difluoro-6-methylbenzo[c]phenanthrene (3), hydrogen atoms are omitted for clarity, ellipsoids are drawn
at the 50% probability level.
With the 4-bromo-13,16-difluorobenzo[s]picene (4) available a first test towards further
functionalization was undertaken by Stille coupling with tris-n-butylstannylferrocene. Gratifyingly,
this provided 4-ferrocenyl-13,16-difluorobenzo[s]picene (5) in 65 % yield. Dark red single crystals
were grown by slow diffusion of n-pentane into a saturated solution of 5 in dichloromethane. 5
crystallizes in the monoclinic space group P21/n with a single molecule forming the asymmetric unit.
3
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The difluoro-substituted phenyl ring is severely bent out of the picene plane (Figure S6). The rather
short fluorinehydrogen distances C4HF1 (2.382 Å) and C15HF2 (2.362 Å) should make the
molecule ideally suited for the aluminum oxide promoted dehydrofluorination reaction. However, the
latter reaction failed irrespectively of reaction time and temperature. Even at temperatures as high as
400 °C and reaction times of more than 120 min, only unchanged starting material was recovered.
Fortunately, its bromo-substituted precursor 4 could be smoothly dehydrofluorinated to provide Idpc-
Br in an excellent yield of 90 % upon conventional heating for less than 120 min neat on preactivated
aluminum oxide to 280 °C.
Scheme 2. Overview over hybrid-structures accessed by cross coupling Idpc-Br with a selection of
differently substituted boronates 6a-h and alkynes 7i-l.
With Idpc-Br in hands, Suzuki and Sonogashira cross-coupling reactions with a variety of differently
substituted phenyl boronates 6a-h and phenylacetylenes 7i-l were pursued (Scheme 2). Yields of
Sonogashira couplings were generally higher (> 90 %) than those of the Suzuki couplings, which
nevertheless still exceeded 80%, except for the case of m-CF3-Ph (76%). The structures and chemical
constitution of all new coupling products 8a-l were confirmed by two-dimensional NMR techniques.
The structure of Idpc-Fc was additionally established by X-ray crystallography. Single crystals
suitable for a diffraction study were grown by slow diffusion of n-hexane into a saturated
dichloromethane solution at r.t. Idpc-Fc crystallizes as dark red tiny platelets in the orthorhombic
space group Pbca with a single molecule in the asymmetric unit; the unit cell contains eight molecules.
In contrast to parent Idpc[21] [CSD code: FAWKIZ] and 9,12-dibromo-Idpc[23] [CSD code: RARRUA],
the only two other structurally characterized members of the Idpc-family,[26] Idpc-Fc is chiral due to
its monosubstitution in conjunction with the bowl shape of the Idpc-fragment; it crystallizes as a
racemic mixture. The ferrocene adopts an exo-orientation with respect to the Idpc. The inter-ring
torsion angle between the planes of the cyclopentadienyl and the adjacent phenyl ring of Idpc is 36.28°
4
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and thus still permits efficient conjugation.[27-28] The orientation of a molecule Idpc-Fc with respect to
its neighboring molecules in the solid state is more complex than it is in the parent Idpc. The latter
forms unidirectional, columnar superimposable, bowl-in-bowl stacks with a uniform bowl-to-bowl
distance of 3.829 Å. In contrast Idpc-Fc forms pairs of columnar bowl-in-bowl stacks. The bowl-
shaped Idpc rings within every pair of stacks share the same orientation whereas neighboring double
stacks are mutually oriented in opposite directions. Individual pairs of columns are separated by
double layers of ferrocenyl substituents (Figure 1). Within every column the individual enantiomers
alternate along the longcolumn axis, which results in a twisted offset of every Idpc-moiety relative to
its nearest neighbor (Figure S8). In consequence, only the Fc-bonded fluoranthene parts of the Idpc -
system do overlap (lower part of Figure 1). The four centroid-centroid distances between the three six-
and the one five- membered rings of the two “fluoranthene”-layers vary only little at values of 3.721 to
3.795 Å (Figure S10/11). These distances are appreciable shorter than those in 9,12-dibromo Idpc
(3.91 Å) and in the parent Idpc (3.829 Å), which is indicative of convex-concave interactions.[29] The
two CC bonds of 1.529(9) Å (C3a–C3e) and 1.531(9) Å (C5a–C5e) formed during the defluorination
step are by far the longest of the entire molecule and approach almost those of a typical C–C single
bond, indicating a lack of conjugation.[22] The bowl depth of 1.406 Å as measured from the centroid of
the central picene ring and the plane defined by atoms C1-C3 and C6-C8 is slightly deeper than in the
parent Idpc (1.334 Å). The -orbital-axis vector (POAV) method is a direct measure of the curvature
of bent -systems.[30],[6] The pyramidalization angle p (p = 90 – ) is a direct measure of deviation
from orthogonality of the - and -orbitals at a certain carbon center. The values calculated based on
the X-ray data of Idpc-Fc for the inner six carbon atoms range from 7.3° to 3.5° and are on average
slightly larger than for unsubstituted Idpc (Figure S12). However, the difference is not significant and
might originate from the different orientation of Idpc-Fc compared to parent Idpc in the crystal.
5
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Figure 1. Packing diagram of Idpc-Fc (8h) in the crystal. Top: View along a-axis; Bottom: stacked view
along b-axis; Enantiomers are shown in different colors, elementary cell shown in black.
The coupling products 8a-8h resulting from Suzuki reactions are in general much more soluble in
common organic solvents such as dichloromethane or tetrahydrofuran as compared to their
Sonogashira counterparts 8i-8l which are significantly less soluble, even in tetrachloroethane. In both
series the Fc-derivatives are the ones with highest solubility. Idpc-Br is only sparingly soluble in
dichloromethane, chloroform and THF. We were therefore interested to see if a coupling of two
molecules Idpc could be achieved or if solubility issues would prevent this reaction. Borylation of
Idpc-Br with bis(pinacolato)diboron under palladium catalysis proceeded smoothly in 1,4-dioxane and
we were pleased to finally isolate a total yield of 50% of dimeric (Idpc)2 over two steps (Scheme 3).
This sets the stage for new inclusion complexes with other -systems based on coupled
indacenopicene moieties or molecular electronics with indacenopicene-based anchoring groups.
However, the limited solubility of (Idpc)2 might be a limiting factor.
Scheme 3. Synthesis of 1,1’-bisindacenopicene (Idpc)2 via Suzuki coupling of Idpc-Br with in situ
generated 1-pinacolatoboryl Idpc (10).
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Electronic absorption spectroscopy
The electronic absorption spectra of indacenopicene and its corresponding derivatives are
characterized by an intense band at 250 nm – 300 nm, a structured band at 300 nm to 340 nm, which is
merged into the low-energy flank of the former, a vibronically resolved transition at 350 nm – 400 nm,
a series of poorly resolved, overlapping bands between 425 nm and 460 nm, as well as a very weak
absorption feature at 460 nm to 530 nm. (c.f. Figure 2 and Table 1).
Figure 2. Electronic absorption spectra of indacenopicene and the new phenyl or phenylethynyl
derivatives in dichloromethane.
Introduction of a phenyl or phenylethynyl substituent at the outer rim of indacenopicene leaves the
general absorption features of the parent arene unchanged despite the lowering from CS symmetry of
Idpc to C1 symmetry. However, hyperchromicity as well as a bathochromic shift of all bands are
observed. The bathochromic shift follows the ordering H < Br < Ph < Idpc ≈ --Ph. Inductive effects
as well as orbital interactions between the frontier orbitals of indacenopicene and the respective
substituent, i.e. the increase of the extended π-system, contribute to this observation. DFT calculations
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indicate that substitution generally affects the LUMO more than the HOMO, i.e. the magnitude of
stabilization of the LUMO is greater than the destabilization of the HOMO. This holds true in
particular for electron-neutral or electron-accepting substituents. Only for the electron donating anisyl
and ferrocenyl substituents the HOMO is more destabilized than the LUMO (c.f. ESI). Introduction of
a ferrocenyl or ethynylferrocenyl substituent results in a gain in intensity and a further bathochromic
shift of the absorption bands and provides an additional broad absorption feature at 519 nm and 532
nm, respectively. Earlier studies on CA congeners yielded very similar results.[31-35] Thus, Topolinski
et al. studied the influence of ferrocenyl substituents linked via various spacers and found that the
bathochomic shift increased along the ordering none < phenyl ≈ ethynyl < vinyl < butadienyl owing to
an increasing π-conjugation between the CA and the ferrocenyl pendant.[35-36] Concerning Idpc-Fc and
Idpc--Fc the stated trend is reversed. Presumably, the greater bowl depth of indacenopicene (vide
supra) in comparison to CA imposes a more complex description of the electronic structure of these
compounds. Interestingly, the benzannulated derivative of indacenopicene, where two indacenopicene
moieties are fused via a joint aromatic ring, does not lower the energy of the electronic transitions as
compared to our phenyl derivatives.[21]
TD-DFT calculations were performed in order to further explore the electronic structure of these
compounds. The five distinct electronic transitions defining the spectral envelope of parent Idpc can
be assigned to ππ* transitions between the highest three occupied and the three lowest unoccupied
frontier orbitals (c.f. Figure 3). Interestingly, our computations discriminate between electronic
transitions that involve the rings of higher (rings A, D, and E) and lower (rings B and C) π-electron
delocalization.[22] Taking this into account, the individual transitions can be described as follows: The
transition at 491 nm (HOMO  LUMO) is mainly centered at the ADE-rings. Next, at 449 nm, the H-
1  LUMO transition involving intramolecular charge transfer (ICT) from the BC to ADE rings can
be identified. The third transition at 384 nm (H-2  LUMO) is best described as a transition between
orbitals that are evenly distributed over the entire indacenopicene π-system. The last two transitions
located at 318 nm (HOMO  L+1) and 286 nm (HOMO  L+2) have again charge-transfer
contributions. However, the direction of the ICT is reversed as compared to the band at lowest energy
and occurs from the ADE to BC rings. Appending a phenyl or ethynylphenyl substituent introduces
some additional ICT character to the transitions of Idpc, the direction of which depends on the
electron-donating or -accepting properties of the latter. However, the energetically second lowest
transition maintains its pure ππ* character. Appending a ferrocenyl or ethynyl-ferrocenyl substituent
augments the ICT with metal-to-ligand charge-transfer (MLCT) character, in particular for the
transition at lowest energy. The vibronic resolution of the band at 390 nm to 360 nm indicates an only
marginal dd* or MLCT admixture to the underlying transition. The bands at even higher energy
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display increasing MLCT contributions (c.f. ESI for a detailed assignment). Despite these MLCT
contributions, changing the polarity of the solvent has only a minor influence on the band positions
(c.f. Figures S44-48). Solvatochromic shifts are very similar to those for indacenopicene itself,
showing that ICT contributions within the π-conjugated framework dominate over those introduced by
the appended phenyl or phenylethynyl substituent.
Figure 3. Frontier MOs of Idpc and corresponding electron density difference maps for individual
transitions. Red color indicates an increase of electron density, and blue color a decrease of electron
density.
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Table 1. Absorption data of synthesized Idpc derivatives in dichloromethane.
-1
Substance
λ in nm (ε in 10³ M cm-1)
Idpc
491 (0.30), 449 (2.17), 426 (2.25), 384 (8.48), 365 (6.30), 318
(10.5), 286 (45.9), 253 (27.8), 241 (32.5)
Idpc-Br
492 (0.60), 451 (2.49), 428 (2.67), 386 (8.83), 367 (6.77), 318
(15.3), 286 (61.7), 254 (29.0)
Idpc-Ph (8a)
498 (1.04), 449 (3.50), 429 (3.50), 387 (11.6), 368 (8.94), 336
(13.2), 319 (18.2), 293 (65.8)
Idpc-Ph-OMe (8b)
Idpc -Ph-NO2 (8c)
Idpc-Ph-o-F (8d)
Idpc-Ph-o-Cl (8e)
Idpc-Ph-(m-OMe)2 (8f)
Idpc-Ph-(m-CF3)2 (8g)
Idpc-Fc (8h)
501 (1.60), 471 (3.15), 447 (4.79), 427 (4.51), 389 (14.4), 369
(11.9), 347 (13.3), 321 (18.7), 294 (56.6)
496 (1.37), 457 (4.00), 427 (4.51), 390 (15.2), 369 (17.6), 329
(19.3), 290 (62.5), 255 (33.7), 242 (37.1)
494 (0.66), 451 (3.17), 429 (3.45), 387 (12.2), 368 (9.32), 336
(13.1), 320 (16.8), 294 (65.7)
492 (0.14), 450 (2.39), 427 (2.68), 387 (10.3), 368 (7.62), 335
(10.9), 319 (13.9), 292 (61.1)
499 (0.62), 451 (2.25), 427 (2.36), 388 (7.93), 369 (6.23), 347
(7.94), 334 (9.85), 322 (12.5), 299 (32.7)
493 (0.59), 455 (2.17), 430 (2.47), 388 (7.83), 368 (6.42), 338
(9.59), 317 (15.2), 294 (42.1)
532 (3.58), 452 (4.16), 428 (3.99), 389 (11.8), 367 (11.2), 346
(13.6), 317 (24.7), 290 (54.1), 255 (44.2), 247 (46.7)
508 (1.65), 449 (4.75), 397 (13.6), 377 (11.7), 352 (14.8), 304
(40.6), 292 (42.6)
Idpc--Ph (8i)
507 (2.73), 464 (6.86), 437 (8.64), 399 (24.3), 376 (28.0), 339
(22.9), 292 (52.4), 248 (41.2)
504 (2.68), 460 (6.45), 435 (7.24), 397 (19.3), 376 (18.6), 364
(22.1), 353 (23.7), 309 (46.4), 293 (53.2)
519 (5.41), 485 (5.87), 459 (6.58), 432 (6.22), 394 (15.2), 373
(14.9), 350 (17.4), 311 (36.8), 290 (56.4)
Idpc--Ph-NO2 (8j)
Idpc--Ph-Br (8k)
Idpc--Fc (8l)
(Idpc)2 (9)
504 (3.44), 474 (6.03), 452 (8.32), 425 (8.62), 391 (25.7), 370
(22.4), 351 (19.6), 322 (31.5), 296 (96.6), 254 (56.4), 244 (61.7)
956 (2.46), 862 (4.24), 758 (7.22), 715 (7.47), 648 (8.61), 509
(6.82), 453 (10.8), 391 (27.1), 371 (29.1)
(Idpc2–)2
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Luminescence spectroscopy
As discussed above the electronic absorption processes in indacenopicene derivatives have ππ*
character with varying degrees of ICT admixture. Photoexcitation of any derivatives at wavelengths
down to 300 nm resulted in fluorescence, which is characterized by a vibrationally poorly resolved
emission band (c.f. Figure 4 and Table 2). In all cases, the emission originates from the S1 state
located at the Idpc moiety. Luminescence measurements carried out at 77 K in a glassy matrix of 2-
methyl-tetrahydrofuran do not reveal any phosphorescence emission, in contrast to what was observed
for CA.[4]
Figure 4. Left: superimposed absorption, excitation and emission spectra of Idpc. Right: superimposed
emission spectra of representative derivatives of the new Idpc’s measured in dichloromethane at room
temperature.
In the series CA, cyclopentacorannulene, indenocorannulene, and indacenopicene the bowl depth
increases from 0.877 Å, to 1.05 Å and 1.07 Å, and finally to 1.35 Å.[37-40] Earlier studies on CA
derivatives revealed that an increasing bowl depth goes in parallel with a decreasing quantum yield, e.
g. from 0.07 for CA to 0.007 for indenocorannulene.[2, 41-42] It was reasoned that the superior rigidity of
the congeners is counterbalanced and even overcompensated by the introduced structural strain, thus
41]
opening nonradiative internal conversion pathways.[2,
Furthermore, photophysical studies on
indenocorannulene derivatives with flat aromatic appendages indicate that the emissive state is located
at flat areas of the geodesic polyarenes, thereby bypassing detrimental structural rearrangement.[41]
With this in mind the following statements concerning our new derivatives can be made: The low
quantum yields of the Idpc´s (Φ = 0.01) adhere to the above-mentioned trend for the series of curved
CAs. Extending the π-system by attachment of a peripheral aryl substituent increases kr along the
series Idpc < Idpc-Ph < Idpc--Ph whereas knr remains rather unchanged, thus improving the
respective quantum yields. Furthermore, the excited state life-times and Stokes shifts remain constant
at circa 4 ns and 2300 cm-1, respectively. The latter in combination with the invariant band shape
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indicate that the excited state is located on the indacenopicene moiety. The time constant for non-
radiative decay knr remains largely constant at approximately 2.4 × 108 s-1, irrespective of whether
electron-donating or -withdrawing substituents are present at the aryl pendent. This indicates that all
derivatives share a common deactivation pathway. Whereas modification of the phenyl-substituted
derivative hardly influences kr and Φ, introducing an ethynyl spacer increases Φ and boosts kr by one
order of magnitude. Fusing two indacenopicenes in (Idpc)2 (9) increases Φ and kr by a factor of four.
However, using ferrocene or ethynyl ferrocene as substituent has no effect on kr or on Φ as compared
to parent Idpc. To the best of our knowledge, compounds 8h and 8l constitute the first ferrocene
derivatives of indacenopicene and are the first geodesic polyarenes containing ferrocene or ethynyl
ferrocene to exhibit luminescence.[35-36, 43] Normally, ferrocene acts as a potent quencher of the excited
states, either by energy transfer or electron transfer, followed by relaxation and the release of thermal
energy.[44] It is reasonable to assume that the ferrocene pendants are electronically decoupled in the
excited state, thus inhibiting quenching processes. This assumption is further supported by inspection
of the absorption and the excitation spectrum of Idpc-Fc (8h). Whereas irradiation into every
absorption feature leads to emission from the energetically lowest excited state, the excitation
spectrum clearly shows that the energetically lowest transition, which, according to quantum chemical
calculations, has a strong contribution from molecular orbitals localized at the ferrocene nucleus, does
not contribute to the emissive state (see ESI). In a very recent paper Kasprzak et al. reported on a
tris(ferrocenylmethidene)sumanene showing a sumanene based luminescence.[45]
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Table 2. Photophysical data of Idpc and the new Idpc derivatives in dichloromethane solutions at room
temperature.
Substance
λmax in Stokes
Φa)
τ1/2
kr in
knr in
nm
shift in
106 s-1
108 s-1
cm-1
Idpc
Idpc-Br
Idpc-Ph (8a)
Idpc-Ph-OMe (8b)
Idpc -Ph-NO2 (8c)
Idpc -Ph-o-F (8d)
Idpc -Ph-o-Cl (8e)
Idpc-Ph-(m-OMe)2 (8f)
Idpc-Ph-(m-CF3)2 (8g)
Idpc-Fc (8h)
553
557
561
568
560
556
554
560
557
566
568
568
568
572
568
2283
2372
2255
2354
2304
2257
2275
2183
2331
2332
2079
2118
2236
2517
2236
0.01
0.01
0.03
0.02
0.03
0.03
0.04
0.04
0.04
0.01
0.1
3.69±0.02
3.82±0.07
4.08±0.02
4.76±0.02
4.32±0.02
4.04±0.02
3.65±0.02
4.11±0.02
3.78±0.02
4.02±0.02
3.93±0.02
3.58±0.02
3.74±0.02
4.21±0.05
3.98±0.02
2.711
2.617
7.357
4.199
6.944
7.419
10.96
9.728
10.57
2.490
25.45
22.33
16.06
2.378
10.06
2.684
2.591
2.379
2.057
2.245
2.399
2.630
2.335
2.537
2.465
2.291
2.568
2.516
2.354
2.414
Idpc--Ph (8i)
0.08
0.06
0.01
0.04
Idpc--Ph-NO2 (8j)
Idpc--Ph-Br (8k)
Idpc--Fc (8l)
(Idpc)2 (9)
a)
Absolute quantum yields are determined utilizing an integrating sphere.
Electrochemistry
Geodesic polyarenes are well known for their ability to be reduced by one or more electrons. Several
studies were devoted to examining their electrochemical properties as well as the structures of the
corresponding reduced forms as their alkali and alkaline earth salts.[22, 46] Whereas CA can be
reversibly reduced by up to four electrons, indacenopicene only displays two reversible one electron
reductions. This is the consequence of the symmetry lowering from C5v to CS and the concomitant
lifting of the degeneracy of the first two lowest unoccupied molecular orbitals.[22]
Cyclic voltammetry was employed in order to investigate the influence of the various substituents on
the reduction potentials of the new indacenopicenes (for experimental voltammograms see the ESI).
The results of our studies on the new Idpc derivatives 8a-8k in 1,2-dichlorobenzene/NBu4PF6 (0.1M)
as the supporting electrolyte are summarized in Figure 5 and Table 3. The cyclic voltammograms are
characterized by two chemically mostly reversible reduction processes. Half-wave potentials of both
redox events are strongly influenced by the substituents on the appended phenyl ring and spread over a
range of more than 400 mV, such that the separation between the half-wave potentials of the first and
the second reduction remains relatively constant at ca. 280 mV to 320 mV. The most anodically shifted
potentials are observed for the nitro derivatives 8c,j while those of the 4-anisyl and ferrocenyl
derivatives 8f,h closely resemble those of parent Idpc. This substituent effect reconfirms that the
appended phenyl or phenylethynyl substituent have a strong bearing on the energies of the lowest
13
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10.1002/chem.202003605
Chemistry - A European Journal
unoccupied frontier MOs, similar to what has been observed for their CA congeners[5, 35-36, 47-48] and in
agreement with the results of our quantum chemical studies. The three pairs of compounds of the
phenyl and ethynylphenyl series with identical substituents on the phenyl ring (H in 8a,i, NO2 in 8c,j,
ferrocenyl in 8h,l) indicate that the ethynyl spacer induces an anodic shift of ca. 100 mV. The same
also holds for the Fe-centered reversible one-electron oxidation of the latter two ferrocene derivatives.
The half-wave potentials of the ferrocene oxidation closely resemble that observed in
ethynylferrocene-appended CA, which oxidizes at 130 mV.[35]
Figure 5. Graphical representation of the first reduction potential of the studied Idpc derivatives
.
14
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Table 3. Half-wave potentials of the indacenopicene derivatives in 1,2-dichlorobenzene/ NBu4PF6 (0.1M)
in mV. Potentials are provided relative to the ferrocene/ferrocenium redox standard set at E1/2 = 0.000 V.
E1/2
E1/2
ΔE1/2 relative to
Compound
Idpc
Idpc-Br
Idpc-Ph (8a)
Idpc-Ph-OMe (8b)
Idpc -Ph-NO2 (8c)
Idpc –Ph-o-F (8d)
Idpc-Ph-o-Cl (8e)
Idpc-Ph-(m-OMe)2 (8f)
Idpc-Ph-(m-CF3)2 (8g)
Idpc-Fc (8h)a)
0/-
0/-2
-
-
Idpc
0
86
33
25
311
47
43
50
104
23
123
413
143
108
149
-1935
-1849
-1902
-1910
-1624
-1888
-1892
-1885
-1831
-1912
-1812
-1522
-1792
-1827
-2221
-2242
-1824
-2224
-2232
-2202
-2107
-2248
-2113
-1743 (-2180)
-2092
-2147
Idpc--Ph (8i)
Idpc--Ph-NO2 (8j)
Idpc--Ph-Br (8k)
Idpc--Fc (8l)b)
(Idpc)2 (9)
-1786/-1858c) -2241
a)
Oxidation potential of 8h at 68 mV. b) Oxidation potential of 8l at 142 mV. c) The two first reductions of
(Idpc)2 (9) as obtained by square wave voltammetry.
In directly linked (Idpc)2 (9) the first reductions of the individual picenes occur in a consecutive
manner with a redox splitting E1/2 of 72 mV. Such behavior entirely results from electrostatic
interactions which is supported by UV/vis-SEC (spectroelectrochemistry) experiments in an optically
transparent thin-layer electrochemical (OTTLE) cell.[49] Upon slowly traversing the convoluted 0/– and
–/2– reductions we observe the growth of low energy absorption bands with peaks/shoulders at 648
nm, 715 nm, 758 nm, and 956 nm, which resemble those in the 360 nm to 500 nm range of neutral
Idpc´s with respect to their pattern and shapes (see Figure 6 and Table 1). The close similarity to the
known absorptions of the corannulenyl radical anion[50] let us assign these features to the monoreduced
(Idpc–)2; i.e. each individual Idpc unit of (Idpc)2 was monoreduced. Most importantly, however, we do
not observe any specific absorption of the mixed-valent radical anion (Idpc2-)(Idpc) at any point of the
electrolysis. According to the E1/2 value of 72 mV and the derived equilibrium constant of 17.7 for
the ensuing comproportionation equilibrium (see equations 1 and 2),[51 ] (Idpc–)2 represents the major
species (64.6 %, with 17.7 % of (Idpc)2 and (Idpc2–)2 each) halfway along the electrolysis, i. e. after
uptake of one electron per Idpc moiety of (Idpc)2.
(Idpc)2 + (Idpc2–)2 ⇄ 2 (Idpc–)2 (eq. 1)
ln(Kc) = FE1/2 / (RT) (eq. 2)
In equation (2) F is the Faraday constant, R is the universal gas constant, T is the absolute temperature,
and E1/2 is the difference of half-wave potentials of the first- and second reductions in Volt.
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Our failure to observe any additional absorption band at even lower energy as it would be typical of an
intramolecular electron transfer transition in an electronically coupled mixed-valent species therefore
indicates that the two Idpc subunits of (Idpc–)2 remain electronically decoupled from each other and,
hence, that the half-wave potential splitting is due to merely electrostatic interactions.
Figure 6. Changes of UV/vis/NIR spectra of (Idpc)2 (9) on reduction in 1,2-
dichlorobenzene/NBu4PF6 (0.1M); * Asterisks denote measurement artefacts of our setup during
switching from UV to NIR (900nm) and during change from background measurement to sample
(660, 580nm).
16
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Conclusion
In summary, we prepared a series of indacenopicene–(ethynyl) arene derivatives by palladium
catalyzed cross-coupling of Idpc-Br with differently substituted aryl boronates and ethynyl arenes. All
products were characterized by by UV/vis spectroscopy, luminescence spectroscopy and
spectroelectrochemistry. Important intermediates were investigated by X-ray diffraction studies. The
synthesized products represent the first members of a family where a functionalization of the rim-
region of Idpc was achieved by C–C cross coupling reaction. All members are fluorescent in solution
with quantum yields of up to 10%. The ethynyl bridged coupling products generally showed improved
quantum yields over their aryl–aryl coupled counterparts. Both ferrocenyl derivatives Idpc-Fc (8h) and
Idpc--Ph (8i) unexpectedly show fluorescence due to a strong decoupling of the organometallic
moiety and the geodesic arene. This has been corroborated by quantum chemical calculations and
above measurements. Idpc-Br is a superb cross-coupling partner and gives access to a whole family of
aryl and phenylethynyl substituted indacenopicene derivatives in a single step in yields exceeding 80
%.
Experimental Section
UV/vis/NIR- and Luminescence Spectroscopy
UV/vis/NIR spectra on CH2Cl2 solutions of the respective compounds were recorded on a TIDAS fiber optic
diode array spectrometer (combined MCS UV/NIR and PGS NIR instrumentation) from J&M in HELLMA
quartz cuvettes with 0.1 cm optical path lengths. Luminescence spectra and lifetimes as well as quantum yields
were measured in CH2Cl2 solutions on a PicoQuant FluoTime 300 spectrometer. Absolute quantum yields were
determined with an integrating sphere within the PicoQuant FluoTime 300 spectrometer.
Cyclic Voltammetry
Cyclic voltammetry analysis was performed in a one-compartment cell with 5–7 mL of 1,2-
dichlorobenzene as the solvent and NBu4PF6 (0.1 M) as the supporting electrolyte. A platinum
electrode (Ø = 1.1 mm, BASI) was used as the working electrode. It was polished with diamond pastes
(1.5 and 1 μm particle size) from Buehler and Wirtz before measurements. A computer-controlled
BASi EPSILON potentiostat was used for recording the voltammograms. An Ag/AgCl wire pseudo
reference electrode and a Pt-wire as auxiliary electrode were used in the measurements. The cell was
connected to an argon-gas cylinder. Potential calibration was performed by adding appropriate
quantities of decamethylferrocene (Cp*2Fe) after all scans of interest had been acquired. Potentials are
reported against the ferrocene/ferrocenium (Cp2Fe0/+) couple, which is 550 mV positive of the
Cp*2Fe0/+ couple under our conditions. Decamethylferrocene had to be used because of a too small
17
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separation between the oxidation wave of ferrocene derivatives 8h and 8l and the usual ferrocene
standard.
The OTTLE cell was also home-built and comprises of a Pt-mesh working and counter electrode and a
thin silver wire as a pseudoreference electrode sandwiched between the CaF2 windows of a
conventional liquid IR cell. Its design follows that of Hartl et al.[49] The working electrode is
positioned in the center of the spectrometer beam. For every measurement, a Wenking POS 2
potentiostat by Bank Elektronik - Intelligent Controls GmbH was used. FT-IR spectra were recorded
using a Bruker Tensor II FT-IR spectrometer. UV/Vis/NIR spectra were obtained on a TIDAS
fiberoptic diode array spectrometer (combined MCS UV/NIR and PGS NIR instrumentation) from
j&m Analytik AG.
Density Functional Theory (DFT) Calculations
The ground state electronic structures of the full models of the studied compounds were calculated by
density functional theory (DFT) methods using the Gaussian 16 program packages.[52] Geometry
optimization followed by vibrational analysis was performed in solvent media. Solvent effects were
described by the polarizable continuum model (PCM) with standard parameters for
dichloromethane.[53] For Fe, the ten‐electron quasirelativistic effective core potential (ECP) MDF10
was used[54] and 6-31G(d) polarized double-ζ basis sets[55] for the remaining atoms were employed
together with the Perdew, Burke, Ernzerhof exchange and correlation functional (PBE0).[56-57] The
GaussSum program package was used to analyze the results,[58] while the visualization of the results
was performed with the Avogadro program package.[59] Graphical representations of molecular orbitals
were generated with the help of GNU Parallel[60] and plotted using the vmd program package[61] in
combination with POV-Ray.[62]
General Methods
Dichloromethane and ethyl acetate for column chromatography were distilled prior to use. All
experiments requiring inert atmosphere were carried out under nitrogen using Schlenk techniques. All
1
other solvents and all commercially available reagents were used without any prior purification. H,
13C and 19F NMR spectra were recorded on Bruker Avance NEO 800, Bruker Avance III 600, Bruker
Avance III 400 and JEOL Resonance ECZ 400S. Deuterated solvents were purchased in sealed
ampules and dried where necessary according to standard procedures.[63] Structure assignments were
done based on 2D-NMR (COSY, HSQC, HMBC, NOESY) experiments. 1H-NMR chemical shifts are
18
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Chemistry - A European Journal
referenced with respect to the chemical shift of the residual protons present in the deuterated solvents
(C2D2Cl4 δ H = 5.91 ppm, δ C = 73.78 ppm; CDCl3: δ H = 7.26 ppm, δ C = 77.16 ppm). EI-MS spectra
were recorded on a JEOL JMS-Q1500GC with direct insertion probe; HR-EI-MS were recorded on a
Waters Micromass GCT TOF spectrometer. IR spectra were recorded on a Perkin ElmerSpectrum 100
ATR unit using compounds in solid state. 4-Bromo-13,16-difluorobenzo[s]picene (4) was obtained by
double photocyclization of the respective stilbenes according to the procedure described by Papaianina
et al.[23] Resulting 4-bromo-13,16-difluorobenzo[s]picene (4) and 4-bromo-13,16-difluoro-
benzo[s]picene (4) were purified by repeated precipitation from cold methanol. All stilbene derivatives
were used as cis/trans isomeric mixtures as received from the Wittig reaction since the isomers do
interconvert under photocyclization conditions. For the aluminum oxide promoted dehydrofluorination
reaction, typically 3.0 g of γ-Al2O3 (neutral, EcoChrom, MP Biomedicals) were activated in Duran
glassware at 525 °C for 30 min in vacuum (10-3 mbar). After cooling to 250 °C, fluoroarene (50 mg)
was added and the reaction was carried out at 280 °C in vacuum (10-3 mbar) until full consumption of
starting material was evident by EI-MS. After cooling to room temperature, products were transferred
to a Soxhlet thimble and extracted using CH2Cl2. Analytically pure products were obtained by
precipitation with MeOH from the corresponding CH2Cl2 extract in typical yields of > 90 %.
General procedure A (Suzuki coupling)
A Schlenk flask purged with nitrogen was charged with Idpc-Br (1 eq.), Pd(PPh3)4 (0.01 eq.), sodium
carbonate (3 eq.), and the corresponding phenylboronic acid (1.5 eq) in a 1,4-dioxane/H2O solution.
The reaction mixture was degassed by bubbling nitrogen via cannula through the mixture for 15 min.
Then, the reaction mixture was heated under reflux conditions until full consumption of starting
material was detected by TLC. The solvent was removed under reduced pressure and the residue was
dissolved in CH2Cl2 (100 mL) and washed with saturated bicarbonate solution (100 mL) and brine
(100 mL). The organic phase was dried over magnesium sulfate, filtered, and the residue was purified
by silica gel chromatography using PE/CH2Cl2 (3:1) as eluent.
General procedure B (Sonogashira coupling)
A Schlenk flask purged with nitrogen was charged with Br-Idpc (1 eq.), CuI (0.025 eq.), PdCl2(PPh3)2
(0.05 eq.), diisopropylamine (2 eq.), and the corresponding phenylacetylene (1.20 eq.). THF was added
and the mixture was degassed by three freeze-pump-thaw cycles. Afterwards, the reaction mixture was
heated to reflux until full consumption of starting material was detected by TLC. The volatiles were
removed under reduced pressure and the residue was extracted with brine (100 mL) and CH2Cl2 (3 x
50 mL). The combined organic phases were dried over magnesium sulfate, filtered, and the residue
was purified by silica gel chromatography using a mixture of toluene/CH2Cl2 (5:2) as eluent.
19
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Compound 8a was synthesized according to general procedure A
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.3 mg,
0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3 eq.) and
phenylboronic acid (36.3 mg, 1.5 eq) in a 1,4-dioxan/H2O (14:1)
solution (50 mL). Orange solid (67.0 mg, 0.17 mmol, 84%).
1H NMR (600 MHz, C2D2Cl4)  = 8.05 (d, 3JHH = 8.8 Hz, 1H, H10),
3
3
3
8.04 (d, JHH = 8.9 Hz, 1H, H11), 7.86 (d, JHH = 8.9 Hz, 1H, H12), 7.74 (d, JHH = 8.7 Hz, 1H, H9),
7.73 (d, 3JHH = 7.2 Hz, 1H, H3), 7.67 (d, 3JHH = 6.9 Hz, 1H, H6), 7.64 (bs, 2H, H4 + H5), 7.63 – 7.58
3
(m, 3H, H8 + H2’ + H6’), 7.50 – 7.45 (m, 2H, H3’ + H5’), 7.43 – 7.40 (m, 1H, H4’), 7.38 (d, JHH
=
3
7.2 Hz, 1H, H2) 7.36 (dd, JHH = 8.2, 7.0 Hz, 1H, H7); 13C NMR (150 MHz, C2D2Cl4)  = 140.59
(C1), 138.85 (C1’), 138.71 (Cq), 138.54 (Cq), 138.17 (Cq), 138.14 (Cq), 138.02 (Cq), 138.00 (2C,
Cq), 137.77 (Cq), 137.05 (Cq), 136.42 (Cq), 129.74 (C10b), 129.69 (C10a),129.68 (2C, C2’ + C6’),
129.00 (C2), 128.94 (C8a), 128.88 (C7), 128.55 (2C, C3’ + C5’), 127.69 (C4’), 127.12 (C12a), 126.93
(C9), 126.74 (C8), 126.17 (C12), 125.67 (C5), 125.43 (C4), 124.19 (C10), 123.94 (C11), 123.82 (C3),
123.58 (C6); IR (cm-1) 2891, 1856, 1547, 1480, 1392, 1254, 1137, 1100, 1071, 1011, 940, 799, 781,
752, 704; MS (EI): m/z (rel. int.) = 400 (100%), 323 (40 %); HRMS (EI) m/z Calcd for C32H16 [M]+:
400.1252. Found: 400.1256.
Compound 8b was synthesized according to general procedure A
OMe
4'
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.30
10
10a
11
10b
9
12
12a
3'
1'
8a
mg, 0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3.00 eq.)
and 4-methoxyphenylboronic acid (45.2 mg, 1.50 eq.) in a 1,4-
dioxan/H2O (14:1) solution (50 mL). Orange solid (67.5 mg, 0.16
mmol, 79 %).
8
2'
1
7
2
Cq
Cq
6
3
5
4
8b
C32H18
430.51
O
3
1H NMR (600 MHz, C2D2Cl4)  = 8.03 (d, JHH = 8.7 Hz, 1H,
H10), 8.02 (d, 3JHH = 9.0 Hz, 1H, H11), 7.86 (d, 3JHH = 8.8 Hz, 1H, H12), 7.72 (d, 3JHH = 8.7 Hz, 1H,
H9), 7.70 (d, 3JHH = 7.2 Hz, 1H, H3), 7.65 (d, 3JHH = 6.9 Hz, 1H, H6), 7.61 (s, 2H, H4 + H5), 7.58 (d,
3JHH = 8.1 Hz, 1H, H8), 7.55 (d, 3JHH = 8.6 Hz, 2H, H2’), 7.34 (dd, 3JHH = 8.0, 7.0 Hz, 2H, H2 + H7),
7.02 (d, 3JHH = 8.6 Hz, 2H, H3’), 3.84 (s, 3H, OMe); 13C NMR (150 MHz, C2D2Cl4)  = 159.15 (C4’),
140.26 (C1), 138.71 (Cq), 138.37 (Cq), 138.16 (Cq), 138.08 (Cq), 137.99 (Cq), 137.91 (Cq), 137.70
(Cq), 137.53(Cq), 137.10 (Cq), 136.38 (Cq), 131.34 (C1’), 130.81 (2C, C2’), 129.66 (C10b), 29.64
(C10a), 128.90 (C8a), 128.83 (C7), 128.59 (C2), 127.19 (C12a), 126.86 (C9), 126.67 (C8), 126.24
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(C12), 125.62 (C5), 125.27 (C4), 124.06 (C11), 123.91 (C10), 123.87 (C3), 123.50 (C6), 114.01 (2C,
C3’), 55.39 (OMe); 1H NMR (400 MHz, CDCl3)  = 8.09 (dd, J = 8.5 Hz, 2H, H10 + H11), 7.91 (d, J
= 8.8 Hz, 1H, H12), 7.77 (d, J = 8.7 Hz, 1H, H9), 7.74 (d, J = 7.1 Hz, 1H, H3), 7.71 (d, J = 6.9 Hz, 1H,
H6), 7.67 (s, 2H, H4 + H5), 7.64 (d, J = 8.1 Hz, 1H, H8), 7.61 (d, J = 8.6 Hz, 2H, H2’), 7.40 (dd, J =
8.0, 6.9 Hz, 1H, H7), 7.38 (d, J = 7.0 Hz, 1H, H2), 7.08 (d, J = 8.6 Hz, 2H, H3’), 3.91 (s, 3H, OMe);
13C NMR (100 MHz, CDCl3)  = 159.56 (C4’), 140.57 (C1), 139.18 (Cq), 138.76 (Cq), 138.61 (Cq),
138.56 (Cq), 138.49 (Cq), 138.40 (Cq), 138.16 (Cq), 138.00 (Cq), 137.58 (Cq), 136.87 (Cq), 131.83
(C1’), 131.03 (2C, C2’), 130.07 (C10b), 130.04 (C10a), 129.24 (C8a), 128.90 (C7), 128.68 (C2),
127.59 (C12a), 126.96 (C9), 126.78 (C8), 126.40 (C12), 125.69 (C5), 125.34 (C4), 124.28 (C11),
124.12 (C10), 123.81 (C3), 123.48 (C6), 114.20 (2C, C3’), 55.56 (OMe); IR (cm-1) 2981, 1856, 1607,
1515, 1480, 1247, 1178, 1101, 951, 809; MS (EI): m/z (rel. int.) = 430 (100 %), 399 (50 %), 323(30
%).
Compound 8c was synthesized according to general procedure A
NO2
4'
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.3 mg,
10
10a
11
10b
9
12
12a
3'
1'
0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3 eq.) and 4-
nitrophenylboronic acid (49.7 mg, 1.5 eq) in a 1,4-dioxan/H2O
(2:1) solution (50 mL). Red solid (73.3 mg, 0.16 mmol, 83 %).
8a
8
2'
1
7
2
Cq
Cq
6
3
5
4
3
1H NMR (600 MHz, C2D2Cl4)  = 8.31 (d, JHH = 8.2 Hz, 2H,
8c
32H15NO2
445.48
C
H3’), 8.09 – 8.02 (m, 2H, H10 + H11 ), 7.76 - 7.71 (m, 5H, H3 +
H9 + H12 + H2’), 7.68 (d, 3JHH = 6.9Hz, 1H, H6), 7.65 (s, 2H), 7.61 (d, 3JHH = 8.0 Hz, 1H, H8), 7.38
3
3
(d, JHH = 7.1 Hz, 1H, H2), 7,37 (dd, JHH = 7.9, 6.9 Hz, 1H, H7); 13C NMR (150 MHz, C2D2Cl4) 
=146.98 (C4‘), 145.80 (C1‘) , 139.44 (C1),, 138.97 (Cq), 138.58 (Cq), 138.17 (Cq), 138.03 (Cq),
137.86 (Cq), 137.76 (Cq), 137.72 (Cq), 137.02 (Cq), 136.38 (Cq), 130.41 (2C, C3’), 129.97 (C10b),
129.54 (C2), 129.02 (C7), 129.00 (C10a), 128.19 (C8a), 127.08 (C3), 126.91 (C8), 126.49 (C12a),
125.84 (2C, C4 + C5), 125.11 (C10), 124.96 (C9), 123.91 (C12), 123.82 (2C, C2’), 123.77 (C11),
123.57 (C6); IR (cm-1) 3035, 1922, 1730, 1593, 1509, 1421, 1341, 1107, 1012, 953, 861, 837, 823,
801, 782, 753, 702; MS (EI): m/z (rel. int.) = 445 (100 %), 399 (30 %), 323 (60 %).
21
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Chemistry - A European Journal
Compound 8d was synthesized according to general procedure A
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.30 mg,
0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3.00 eq.) and 2-
fluorophenylboronic acid (41.6 mg, 1.50 eq.) in a 1,4-dioxan/H2O
(14:1) solution (50 mL). orange solid (74.5 mg, 0.18 mmol,89%).
3
1H NMR (600 MHz, C2D2Cl4)  = 8.01 (d, JHH = 8.7 Hz, 1H, H10),
8.00 (d, 3JHH = 8.9 Hz, 1H, H11), 7.73 – 7.70 (m, 2H, H3 + H9), 7.65 (d, 3JHH = 6.9 Hz, 1H, H6), 7.62
(dd, 3JHH = 8.9, 2.2 Hz, 1H, H12), 7.60 (bs, 2H, H4 + H5), 7.58 (d, 3JHH = 8.1 Hz, 1H, H8), 7.46 (dd,
3
3JHH = 7.5, 1.7 Hz, 1H, H6’), 7.41 (ddd, J = 9.9, 4.9 , 2.3 Hz, 1H, H4’), 7.37 (d, JHH = 7.1 Hz, 1H,
3
H2), 7.34 (dd, JHH = 8.1, 7.0 Hz, 1H, H7), 7.25 (m, 1H, H5’), 7.21 (m, 1H, H3’); 19F NMR (375
MHz, C2D2Cl4)  = -113.88; 13C NMR (150 MHz, C2D2Cl4)  = 159.61 (d, J = 247.5 Hz, C2’), 138.70
(Cq), 138.62 (Cq),, 138.61 (Cq), 138.13 (Cq), 138.09 (Cq), 138.01 (Cq), 137.94 (Cq), 137.76 (Cq),
136.66 (Cq), 136.39 (Cq), 134.08 (C1), 132.17 (d, J = 3.3 Hz, C6’), 130.18 (C2), 129.79 (C10b),
129.74 (C7), 129.62 (C10a), 128.87 (d, J = 6.8 Hz, C4’), 128.85 (C8a), 127.60 (C12a) , 126.90 (C9),
126.75 (C8), 126.27 (d, J = 15.3 Hz, C1’), 125.99 (d, J = 2.3 Hz, C12) , 125.64 (C5), 125.57 (C4),
124.29 (d, J = 3.5 Hz, C5’), 124.16 (C11), 123.88 (C10), 123.59 (C6), 123.49 (C3), 115.93 (d, J = 22.2
Hz, C3’); IR (cm-1) 2957, 2874, 1464, 1381, 1251, 1129, 1097, 1073, 1004, 943, 793, 779, 753, 739;
MS (EI): m/z (rel. int.) = 418 (100 %), 399 (80 %), 323 (30 %).
Compound 8e was synthesized according to general procedure A
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.30 mg,
0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3.00 eq.) and 2-
chlorophenylboronic acid (46.5 mg, 1.50 eq.) in a 1,4-dioxan/H2O
(14:1) solution (50 mL). Orange solid (75. 0 mg, 0.17 mmol, 87 %)
3
1H NMR (600 MHz, CDCl3)  = 8.11 (d, JHH = 8.7 Hz, 1H, H10),
3
3
3
8.07 (d, JHH = 8.8 Hz, 1H, H11), 7.79 (d, JHH = 8.7 Hz, 1H, H9), 7.78 (d, JHH = 7.1 Hz, 1H, H3),
7.73 (d, 3JHH = 6.9 Hz, 1H, H6), 7.72 – 7.68 (m, 2H, H4 + H5), 7.65 (d, 3JHH = 8.0 Hz, 1H, H8), 7.59 –
7.56 (m, 1H, H3’), 7.53 (d, 3JHH = 8.8 Hz, 1H, H12), 7.45 – 7.43 (m, 1H, H6’), 7.43 – 7.38 (m, 3H, H7
+ H4’ + H5’), 7.34 (d, 3JHH = 7.1 Hz, 1H, H2); 13C NMR (150 MHz, CDCl3)  = 139.17 (Cq), 139.07
(Cq), 139.00 (Cq), 138.80 (Cq), 138.68 (Cq), 138.67 (Cq), 138.60 (Cq), 138.37 (Cq), 138.03 (C1’),
137.91 (C1), 137.00 (Cq), 136.93 (Cq), 133.83 (C2’), 132.30 (C6’), 130.24 (C10b), 130.15 (C10a),
130.03 (C2), 129.99 (C3’), 129.33 (C4’), 129.26 (C8a), 128.94 (C7), 128.01 (C12a), 127.06 (C9),
22
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126.88 (C8), 126.80 (C5’), 126.17 (C12), 125.75 (C5), 125.73 (C4), 124.32 (C11), 124.15 (C10),
123.58 (C6), 123.30 (C3); IR (cm-1) 2923, 2360, 1511, 1412, 1241, 1134, 1015, 960, 821, 808, 756;
MS (EI): m/z (rel. int.) = 434 (100 %), 399 (50 %), 323 (30 %).
Compound 8f was synthesized according to general procedure A
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.3
mg, 0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3 eq.)
and 3,5-dimethoxyphenylboronic acid (54.1 mg, 1.5 eq) in a 1,4-
dioxan/H2O (14:1) solution (50 mL). Orange solid (69.4 mg,
0.16 mmol, 76 %).
3
1H NMR (600 MHz, C2D2Cl4)  = 8.03 (d, JHH = 8.8 Hz, 1H,
3
H11), 8.03 (d, JHH = 8.8 Hz, 1H, H10) 7.91 (d, 3JHH = 8.9 Hz, 1H, H12), 7.72 (d, 3JHH = 8.7 Hz, 1H,
H9), 7.71 (d, 3JHH = 7.3Hz, 1H, H3), 7.66 (d, 3JHH = 6.9 Hz, 1H, H6), 7.62 (s, 2H, H4 + H5), 7.59 (d,
3JHH = 8.1 Hz, 1H, H8), 7.38 (d, 3JHH = 7.2 Hz, 1H, H2), 7.34 (dd, 3JHH = 8.2, 7.0 Hz, 1H, H7), 6.75 (d,
4JHH = 2.3 Hz, 2H, H2’), 6.52 (t, 4JHH = 2.3 Hz, 1H, H4’). 3.81 (s, 6H, 2x OMe); 13C NMR (150 MHz,
C2D2Cl4)  = 160.53 (2C, C3‘), 140.95 (C1‘), 140.38 (C1), 138.67 (Cq), 138.54 (Cq), 138.16 (Cq),
138.10 (2C, Cq), 137.97 (2C, Cq), 137.73 (Cq), 136.99 (Cq), 136.39 (Cq), 129.74 (C10b), 129.62
(C10a), 128.91 (C8a), 128.86 (C2), 128.79 (C7), 127.03 (C12a), 126.90 (C9), 126.73 (C8), 126.13
(C12), 125.64 (C5),, 125.43 (C4), 124.20 (C11), 123.91 (C10), 123.69 (C3), 123.56 (C6), 107.91
1
(C2‘), 99.64 (C4‘), 55.50 (2C, 2x OMe); H NMR (400 MHz, CDCl3)  = 8.07 (d, J = 8.8 Hz, 2H,
H10 + H11), 7.94 (d, J = 8.9 Hz, 1H, H12), 7.75 (d, J = 8.7 Hz, 1H, H9), 7.73 (d, J = 7.1 Hz, 1H, H3),
7.69 (d, J = 6.9 Hz, 1H, H6), 7.64 (s, 2H, H4 + H5), 7.62 (d, J = 8.1 Hz, 1H, H8), 7.42 (d, J = 7.1 Hz,
1H, H2), 7.38 (dd, J = 8.1, 6.9 Hz, 1H, H7), 6.81 (d, J = 2.3 Hz, 2H, H2’), 6.58 (t, J = 2.3 Hz, 1H,
H4’), 3.89 (s, 6H, 2x OMe);13C NMR (100 MHz, CDCl3)  = 160.94 (2C, C3‘), 141.39 (C1‘), 140.70
(C1), 139.12 (Cq), 138.87 (Cq), 138.58 (Cq), 138.51 (Cq), 138.47 (Cq), 138.40 (Cq), 138.38 (Cq),
138.12 (Cq), 137.44 (Cq), 136.83 (Cq), 130.09 (C10b), 129.97 (C10a), 129.22 (C8a), 128.88 (C2),
128.83 (C7), 127.39 (C12a), 126.95 (C9), 126.80 (C8), 126.26 (C12), 125.67 (C5), 125.45 (C4),
124.40 (C11), 124.09 (C10), 123.61 (C3), 123.50 (C6), 108.13 (C2’), 99.86 (C4’), 55.66 (2C, 2x
OMe); IR (cm-1) 2956, 1592, 1455, 1421, 1264, 1204, 1155, 1066, 896, 810, 728; MS (EI): m/z (rel.
int.) = 460 (100 %) 323 (40 %).
23
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Compound 8g was synthesized according to general procedure A
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.30
mg, 0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3.00 eq.)
and 3,5-methoxyphenylboronic acid (76.7 mg, 1.50 eq.) in a 1,4-
dioxan/H2O (14:1) solution (50 mL). Orange solid (67.5 mg, 0.16
mmol, 79 %).
1H NMR (400 MHz, CDCl3)  = 8.12 – 8.09 (m, 3H, H11 + H2’),
8.07 (d, J = 8.7 Hz, 1H, H10), 7.98 (bs, 1H, H4’), 7.78 (d, J = 8.7 Hz, 1H, H9), 7.75 (d, J = 7.1 Hz,
1H, H3), 7.72 (d, J = 6.9 Hz, 1H, H6), 7.69 (d, J = 8.8 Hz, 1H, H12), 7.66 (s, 2H, H4 + H5), 7.65 (d, J
= 8.1 Hz, 1H, H8), 7.41 (dd, J = 8.1, 6.9 Hz, 1H, H7). 7.40 (d, J = 7.1 Hz, 1H, H2); 19F NMR (375
MHz, C2D2Cl4)  = -62.22; 13C NMR (100 MHz, CDCl3)  = 141.48 (C1’), 139.96 (Cq), 139.36 (Cq),
139.04 (Cq), 138.58 (Cq), 138.43 (Cq), 138.32 (Cq), 138.24 (Cq), 138.02 (Cq), 137.47 (Cq), 137.11
(Cq), 136.82 (C1), 132.13 (q, 2JCF = 33.3 Hz, (2C, C3’), 130.31 (C10b), 129.82(C10a), 129.80 (m, 2C,
C2’), 129,60 (C2), 129.34(C8a), 129.08 (C7), 127.16 (C9), 127.02 (C8), 126.69 (C12a), 125.89 (C5),
1
125.88 (C4), 125.37 (C11), 124.71 (C12), 124.07 (C10), 123.75 (C6), 123.47 (C3), 123.51 (q, JCF
=
3
272.9 Hz, C5’) 121.51-121.49 (hept, JCF = 3.6 Hz, C4’); IR (cm-1) 2957, 2875, 1464, 1421, 1382,
1215, 1149, 1065, 892, 807, 731; MS (EI): m/z (rel. int.) = 536 (100 %) 467 (30 %) 398 (20 %), 323
(50 %).
Compound 8h was synthesized according to general procedure A
using Idpc-Br (80.0 mg, 0.20 mmol, 1.00 eq.), Pd(PPh3)4 (2.3 mg,
0.01 eq.), sodium carbonate (63.0 mg, 0.60 mmol, 3 eq.) and
ferroceneboronic acid (68.4 mg, 1.5 eq) in a 1,4-dioxane/H2O
(14:1) solution (50 mL). Red solid (84.7 mg, 0.17 mmol, 84 %).
Crystals suitable for X-ray diffraction were grown by slow
diffusion of n-hexane into a concentrated solution of 8h in CH2Cl2.
1H NMR (600 MHz, C2D2Cl4): = 8.38 (d, 3JHH = 8.9 Hz, 1H, H12), 8.13 (d, 3JHH = 8.9 Hz, 1H, H11),
3
3
3
8.11 (d, JHH = 8.8 Hz, 1H, H10), 7.78 (d, JHH = 8.7 Hz, 1H, H9), 7.69 (d, JHH = 6.9 Hz, 1H, H6),
3
3
3
7.65 (d, JHH = 7.4 Hz, 1H, H5), 7.62j (d, JHH = 7.7 Hz, 2H, H8 + H4), 7.59 (d, JHH = 7.3 Hz, 1H,
3
3
H3), 7.48 (d, JHH = 7.4 Hz, 1H, H2), 7.37 (t, JHH = 7.5 Hz, 1H, H7), 4.82 (s, 2H, H2’), 4.46 (s, 2H,
H3’), 4.13 (s, 5H, H4’); 13C NMR (150 MHz, C2D2Cl4)  = 138.80 (Cq), 138.45 (Cq), 138.29 (Cq),
138.21 (Cq), 138.09 (Cq), 138.07 (Cq), 137.81 (Cq), 137.61 (Cq), 137.08 (C1), 136.87 (Cq), 136.44
24
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(Cq), 129.61 (C10a), 129.50 (C10b), 128.96 (C8a), 128.90 (C7), 128.34 (C2), 127.33 (C12a), 126.93
(C9), 126.68 (C8), 126.41 (C12), 125.67 (C5), 125.07 (C4), 123.99 (C10), 123.61 (C3), 123.55 (C6),
123.50 (C11), 74.04 (C1’), 70.33 (5C, C4’), 69.73 (2C, C2’), 69.64 (2C, C3’); IR (cm-1) 2958, 2875,
1463, 1382, 1251, 1151, 1073, 956, 817, 740; MS (EI): m/z (rel. int.) = 508 (100 %), 323 (60 %);
HRMS (EI) m/z Calcd for C36H20Fe [M]+: 508.0914. Found: 508.0916.
Compound 8i was synthesized according to general procedure B
using Idpc-Br (0.1 g, 0.24 mmol, 1.00 eq.), CuI (1.2 mg, 0.025
eq.), PdCl2(PPh3)2 (8.4 mg, 0.05 eq.), diisopropylamine (0.1 mL,
2.00 eq.) and phenylacetylene (0.04 mL, 0.29 mmol, 1.20 eq.)
dissolved in 20 ml THF. Red solid (90.4 mg, 0.21 mmol, 89 %).
1H NMR (600 MHz, C2D2Cl4)  = 8.12 (d, J = 8.8 Hz, 1H, H11),
8.07 (d, J = 8.7 Hz, 1H, H10), 8.05 (d, J = 8.7 Hz, 1H, H12), 7.77 (d, J = 8.7 Hz, 1H, H9), 7.68 (d, J =
6.9 Hz, 1H, H6), 7.64 (d, J = 7.2 Hz, 1H, H3), 7.63 – 7.60 (m, 4H, H4 + H5 + H3’ ), 7.57 (d, J = 7.2
Hz, 1H, H2), 7.39 – 7.32 (m, 4H, H7 + H8, H2’), 7.28 – 7.22 (m, 1H, H4’);13C NMR (150 MHz,
C2D2Cl4)  = 138.89 (Cq), 138.71 (Cq), 138.57 (Cq), 138.19 (Cq), 138.07 (Cq), 138.05 (Cq), 138.01
(Cq), 137.84 (Cq), 136.44 (Cq), 136.33 (Cq), 132.83 (C2), 131.73 (2C, C2’), 130.23 (C10b), 129.73
(C10a), 129.06 (C12a), 128. 99 (C7), 128.98 C8a), 128.70 (C4’), 128.47 (2C, C3’), 127.07 (C9),
126.89 (C8), 125.85 (C5), 125.77 (C4), 125.55 (C12) , 124.55 (C11), 123.97 (C10), 123.75 (C6),
123.34 (C3), 122.82 (C1’), 120.72 (C1), 95.31 (Cac2), 87.05 (Cac1); ); IR (cm-1) 2957, 2873, 1463,
1380, 1209, 1138, 1067, 955, 836, 812, 741; MS (EI): m/z (rel. int.) = 424 (100 %), 323 (40 %).
Compound 8j was synthesized according to general procedure
B using Idpc-Br (0.1 g, 0.24 mmol, 1.00 eq.), CuI (1.2 mg,
0.025 eq.), PdCl2(PPh3)2 (8.4 mg, 0.05 eq.), diisopropylamine
(0.1 mL, 2.00 eq.) and 4-nitrophenylacetylene (43.0 mg, 0.29
mmol, 1.20 eq.) dissolved in 20 ml THF. Red solid (93.5 mg,
0.20 mmol, 83 %).
1H NMR (600 MHz, C2D2Cl4)  = 8.19 (d, J = 8.7 Hz, 2H,
H3’), 8.13 (d, J = 8.8 Hz, 1H, H11), 8.07 (d, J = 8.7 Hz, 1H,
H10), 8.00 (d, J = 8.7 Hz, 1H, H12), 7.77 (d, J = 8.7 Hz, 1H, H9), 7.73 (d, J = 8.8 Hz, 2H, H2’), 7.69
(d, J = 6.9 Hz, 1H, H6), 7.66 (d, J = 7.2 Hz, 1H, H3), 7.64 – 7.59 (m, 4H, H2 + H4 + H5 + H8), 7.46
25
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13
(dd, J = 8.1, 6.9 Hz, 1H, H7); C NMR (150 MHz, C2D2Cl4)  = 146.81 (C4’), 139.75 (Cq), 139.20
(Cq), 138.50 (Cq), 138.22 (Cq), 138.10 (Cq), 138.02 (Cq), 137.89 (Cq), 137.83 (Cq), 136.44 (Cq),
136.33 (Cq), 133.69 (C2), 132.41(2C, C2’), 130.36 (C10b), 129.99 (C1’), 129.66 (C10a), 129.06 (C7),
129.03 (C8a), 128.90 (C12a), 127.16 (C9), 127.00 (C8), 126.11 (C5), 125.85 (C4), 125.22 (C12),
124.92 (C11), 123.94 (C10), 123.86 (C6), 123.65(2C, C3’), 123.20 (C3), 119.34 (C1), 93.13 (Cac2),
92.44 (Cac1); IR (cm-1): 3046, 1902, 1859, 1547, 1480, 1421, 1392, 1253, 1136, 1099, 1071, 1010,
940, 890, 857, 816, 798, 778, 751, 704; MS (EI): m/z (rel. int.) = 469 (100 %), 323 (30 %); Anal.
Calcd for C34H15NO2: 86.98 % (C), 3.22 % (H), 2.98 % (N), Found: 86.69 % (C), 3.55 % (H), 3.09 %
(N).
Compound 8k was synthesized according to general procedure B
using Idpc-Br (0.1 g, 0.24 mmol, 1.00 eq.), CuI (1.2 mg, 0.025
eq.), PdCl2(PPh3)2 (8.4 mg, 0.05 eq.), diisopropylamine (0.1 mL,
2.00 eq.) and 4-bromophenylacetylene (53.0 mg, 0.29 mmol,
1.20 eq.) dissolved in 20 ml THF. Red solid (102 mg, 0.20
mmol, 82 %).
1H NMR (600 MHz, C2D2Cl4)  = 8.10 (d, J = 8.8 Hz, 1H, H11), 8.06 (d, J = 8.6 Hz, 1H, H10), 8.00
(d, J = 8.7 Hz, 1H, H12), 7.76 (d, J = 8.7 Hz, 1H, H9), 7.68 (d, J = 6.8 Hz, 1H, H6), 7.64 – 7.58 (m,
4H, H3 + H4 + H5 + H8), 7.56 (d, J = 7.2 Hz, 1H, H2), 7.52 – 7.44 (m, 4H, H2’ + H3’), 7.37 (t, J =
7.5 Hz, 1H, H7); 13C NMR (150 MHz, C2D2Cl4)  = 138.94 (2C, Cq), 138.56 (Cq), 138.18 (Cq),
138.05 (Cq), 137.98 (2C, Cq), 137.83 (Cq), 136.43 (Cq), 136.32 (Cq), 133.13 (2C, C2’), 132.96 (C2),
131.67 (2C, C3’), 130.24 (C10b), 129.68 (C10a), 129.00 (C7), 128.99 (8a), 128.95 (12a), 127.07 (C9),
126.91 (C8), 125.88 (C5), 125.77 (C4), 125.42 (C12), 124.61 (C11), 123.94 (C10), 123.76 (C6),
123.29 (C3), 122.78 (1’), 121.89 (4’), 120.31 (C1), 94.14 (Cac2), 88.20 (Cac1); IR (cm-1) 3046, 2210,
1871, 1859, 1547, 1480, 1421, 1392, 1253, 1137, 1099, 1071, 1010, 940, 890, 857, 816, 798, 778, 751,
704; MS (EI): m/z (rel. int.) = 504 (95 %), 502 (100 %), 423 (40 %), 323 (30 %).
26
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Compound 8l was synthesized according to general procedure
B using aryl Idpc-Br (83.0 mg, 0.21 mmol, 1.00 eq.), CuI (1.0
mg, 0.025 eq.), PdCl2(PPh3)2 (7.4 mg, 0.05 eq.),
diisopropylamine (0.1 mL, 2.00 eq.) and ethynylferrocene
(52.0 mg, 0.25 mmol, 1.20 eq.) dissolved in 25 ml THF. Red
solid (101 mg, 0.19 mmol, 92 %).
1H NMR (500 MHz, C2D2Cl4)  = 8.12 (d, J = 8.8 Hz, 1H,
H11), 8.06 (d, J = 8.7 Hz, 1H, H10), 8.01 (d, J = 8.8 Hz, 1H, H12), 7.76 (d, J = 8.7 Hz, 1H, H9), 7.67
(d, J = 7.0 Hz, 1H, H6), 7.63 – 7.57 (m, 4H, H3 + H4 + H5 + H8 ), 7.51 (d, J = 7.3 Hz, 1H, H2), 7.36
(dd, J = 8.1, 7.0 Hz, 1H, H7), 4.58 (t, J = 1.8 Hz, 2H, H2’), 4.27 (t, J = 1.8 Hz, 2H, H3’), 4.25 (s, 5H,
H4’); 13C NMR (125 MHz, C2D2Cl4)  = 138.66 (Cq), 138.64(Cq), 138.18 (Cq), 138.16 (Cq), 138.05
(Cq), 137.97 (Cq), 137.94 (Cq), 137.79 (Cq), 136.44 (Cq), 136.38 (Cq), 132.21 (C2), 130.14 (C10b),
129.71 (C10a), 129.08 (C12a), 128.97 (C8a), 128.93 (C7), 127.01 (C9), 126.82 (C8), 125.72 (C5),
125.64 (C4), 125.58 (C12), 124.36 (C11), 123.93 (C10), 123.65 (C6), 123.44 (C3), 121.68 (C1), 95.04
(Cac2), 83.35 (Cac1), 71.69 (2C, C2’), 70.13 (5C, C4’), 69.30 (2C, C3’), 64.74 (C1’); IR (cm-1) 2958,
2875, 1463, 1382, 1149, 956, 801 752, 739; MS (EI): m/z (rel. int.) = 532 (100 %), 323 (40 %);
HRMS (EI) m/z Calcd for C38H20Fe [M]+: 532.0914. Found: 532.0921.
4-Ferrocenyl-13,16-difluorobenzo[s]picene (5) was synthesized by
adding to a solution of Pd(PPh3)4 (97.0 mg, 0.08 mmol, 0.05 eq.) and
cesium fluoride (168 mg, 1.11 mmol, 2.2 eq.) in dry DMF (2 mL), tri-n-
butylstannylferrocene (250 mg, 0.53 mmol, 1.0 eq.), a suspension of
Idpc-Br (250 mg, 0.56 mmol, 1.1 eq.) in dry DMF (9 mL), and
copper(I)iodide (45.0 mg, 0.24 mmol, 0.5 eq.). The reaction mixture was
heated at 50 °C for 15 h whilst monitoring the reaction via EI-MS until full consumption of starting
material. Upon cooling to room temperature the reaction mixture was filtered over a short celite plug
with ethyl acetate (150 mL). The filtrate was washed with bicarbonate solution (2 x 30 mL), water (2 x
30 mL) and brine (30 mL), dried over magnesium sulfate, filtered and concentrated under reduced
pressure. Column chromatography on silica using PE/ethyl acetate = 9:1 as eluent yielded a deep red
powder. Repeated washing with copious amounts of n-pentane yielded title compound 5 as red powder
(200 mg, 0.37 mmol, 65 %). Crystals suitable for X-ray diffraction were grown by slow diffusion of n-
pentane into a concentrated solution of 5 in CH2Cl2.
27
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3
3
1H NMR (800 MHz, CDCl3)  = 8.75 (d, JHH = 9.1 Hz, 1H, H5), 8.52 (d, JHH = 8.8 Hz, 1H, H7),
3
6
3
8.47 (d, JHH = 9.1 Hz, 1H, H6), 8.23 (dd, JHF (through space) = 13.8 Hz, JHH = 8.2 Hz, 1H, H12),
6
3
3
8.11 (dd, JHF (through space) = 13.0 Hz, JHH = 7.7 Hz, 1H, H1), 8.11 (d, JHH = 8.7 Hz, 1H, H8),
7.97 (d, 3JHH = 7.9 Hz, 1H, H9), 7.93 (d, 3JHH = 7.7 Hz, 1H, H3), 7.61 (dd, 3JHH = 8.2 Hz, 7.0 Hz, 1H,
3
3
H11), 7.59 (dd, JHH = 7.9 Hz, 7.0 Hz, 1H, H10), 7.54 (dd, JHH = 9.1 Hz, 7.7 Hz, 1H, H2), 7.39 (d,
3JHH = 7.4 Hz, 1H, H14), 7.38 (d, 3JHH = 7.4 Hz, 1H, H15), 4.74 (s, 2H, H2’ + H5’), 4.49 (s, 2H, H3’
5
+ H4’), 4.30 (s, 5H, H6’); 19F NMR (376 MHz, CDCl3)  = -104.07 (d, JFF = 17.7 Hz, 1F, F16), -
5
1
104.20 (d, JFF = 17.7 Hz, 1F, F13); 13C NMR (200 MHz, CDCl3)  = 155.34 (dd, JCF = 246.2 Hz,
1
4
4JCF = 1.8 Hz, C13), 155.31 (dd, JCF = 250.2 Hz, JCF = 1.7 Hz, C16), 135.55 (C4), 132.47 (C8a),
131.03 (C4a), 130.77 (d, 4JCF = 3.2 Hz, C16c), 130.35 (d, 4JCF = 3.1 Hz, C12a), 130.06 (C6b), 129.83
(d, 5JCF (through space) = 14.4 Hz, C12), 129.82 (C6a), 129.51 (C8), 128.83 (d, 5JCF (through space) =
14.2 Hz, C1), 128.40 (C3), 127.64 (C5), 127.29 (C9), 126.26 (C10), 125.36 (C11), 124.54 (C3),
123.74 (d, 3JCF = 3.0 Hz, C12b), 123.53 (d, 3JCF = 3.1 Hz, C16b), 120.54 (dd, 2JCF = 13.7 Hz, 3JCF =
2
2.0 Hz, C12c), 120.27 (dd, JCF = 14.0 Hz, 3JCF = 2.5 Hz, C16a), 119.89 (C8), 119.37 (C6), 114.46
3
2
3
(dd, 2JCF = 11.8 Hz, JCF = 9.6 Hz, C14), 114.32 (dd, JCF = 12.2 Hz, JCF = 10.0 Hz, C15), 87.98
(C1’), 71.95 (C5’), 70.46 (C2’), 70.18 (5C, C6’), 68.69 (2C, C3’+4’); MS (EI): m/z (rel. int.) = 548.
(100 %), 363 (80 %).
Idpc-B(pin) (10) was synthesized using Idpc-Br (100 mg, 0.25
mmol, 1.00 eq.), Pd(dppf)Cl2 (10.0 mg, 0.01 mmol, 0.05 eq.),
potassium acetate (73.0 mg, 0.74 mmol, 3.00 eq.), and
bis(pinacolato)diboron (94.5 mg, 0.37 mmol, 1.50 eq.) dissolved in
dry 1,4-dioxane (60 mL). The mixture was heated under reflux until
full consumption of starting materials (TLC). The volatiles were
removed under reduced pressure and water (200 mL) was added to
the crude. The resulting mixture was extracted with CH2Cl2 (3 x 100 mL). The organic phases were
dried over magnesium sulfate, filtered, and the solvent was removed under reduced pressure. The
crude product was purified by column chromatography on silica using a gradient system consisting of
initially PE/CH2Cl2 = 3:1 gradually changed to CH2Cl2 as eluent to obtain boronic acid pinacol ester
10 as an orange solid (101 mg, 0.22 mmol, 90 %).
3
3
1H NMR (400 MHz, CDCl3): = 8.48 (d, JHH = 8.9 Hz, 1H), 8.13 (d, JHH = 8.9 Hz, 1H), 8.12 (d,
3JHH = 8.7 Hz, 1H), 7.98 (d, 3JHH = 6.9 Hz, 1H), 7.78 (d, 3JHH = 8.8 Hz, 1H), 7.71 (d, 3JHH = 6.9, 2H),
7.67 – 7.66 (m, 2H), 7.65 (d, 3JHH = 8.2 Hz, 1H), 7.39 (dd, 3JHH = 8.2, 6.9 Hz, 1H), 1.44 (s, 12H); 13C
28
This article is protected by copyright. All rights reserved.

10.1002/chem.202003605
Chemistry - A European Journal
NMR (100 MHz, CDCl3) = 141.91, 139.40, 139.06, 138.61, 138.59 138.41, 138.18, 137.97, 136.94,
136.47, 133.04, 130.25, 130.07, 129.16, 128.78, 128.68, 126.92, 126.88, 125.91, 125.43, 124.19,
124.15, 123.57, 122.70, 83.97, 25.16; IR (cm-1) 2981, 1697, 1594, 1507, 1422, 1341, 1143, 1106,
1061, 954, 807, 783, 753, 703; MS (EI): m/z (rel. int.) = 450 (100 %), 323 (60 %).
1,1’-Bisindacenopicene (Idpc)2 (9) was synthesized
according to general procedure A using Idpc-Br
(23.0 mg, 0.06 mmol, 1.00 eq.), Pd(PPh3)4 (1.0 mg,
0.01 eq.), sodium carbonate (24.0 mg, 0.22 mmol,
3.00 eq.) and boronic acid pinacol ester 10 in a 1,4-
dioxane/H2O (14:1) solution (50 mL). (30.0 mg, 0.07
mmol, 1.2 eq.) Red solid (21.5 mg, 0.03 mmol, 60
%).
1H NMR (600 MHz, C2D2Cl4): = 8.05 (d, 3JHH = 8.6 Hz, 1H, H10), 7.99 (d, 3JHH = 8.8 Hz, 1H, H11),
7.83 (d, 3JHH = 6.9 Hz, 2H, H3), 7.75 (d, 3JHH = 8.6 Hz, 2H, H9), 7.73 – 7.67 (m, 8H, H4 + H5 + H6 +
3
3
3
H12), 7.62 (d, JHH = 8.1 Hz, 2H, H8), 7.52 (d, JHH = 6.9 Hz, 2H, H2), 7.38 (t, JHH = 7.5 Hz, 2H,
H7); 13C NMR (150 MHz, C2D2Cl4)  = 138.79 (Cq), 138.67 (Cq), 138.54 (Cq), 138.29 (Cq), 138.25
(Cq), 138.13 (Cq), 138.07 (Cq), 137.95 (Cq), 137.46 (C1’), 136.94 (Cq), 136.48 (Cq), 130.69 (C2),
129.95 (C10b), 129.76 (C10a), 128.98 (C8a), 128.96 (C7), 128.28 (C12a), 127.02 (C9), 126.83 (C8),
126.50 (C12), 125.80 (C5), 125.69 (C4), 124.21 (C11), 123.84 (C10), 123.68 (C6), 123.67 (C3); IR
(cm-1) 3029, 2891, 2202, 1869, 1591, 1504, 1415, 1375, 1339, 1250, 1132, 1107, 951, 892, 852, 801,
780, 757, 704, 667; MS (EI): m/z (rel. int.) = 646 (100 %), 323 (50 %).
29
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