Highly fluorous porphyrins as model compounds for molecule interferometry

Article abstract of DOI:10.1002/ejoc.201100638

The synthesis and characterization of seven tailor-made highly fluorous porphyrin derivatives are described, as large perfluoroalkyl-functionalized organic molecules are the most complex objects for which the quantum wave nature has been observed so far.

Full text of DOI:10.1002/ejoc.201100638

FULL PAPER
DOI: 10.1002/ejoc.201100638
Highly Fluorous Porphyrins as Model Compounds for Molecule Interferometry
Jens Tüxen,[a] Sandra Eibenberger,[b] Stefan Gerlich,[b] Markus Arndt,[b] and
Marcel Mayor*[a,c]
Keywords: Fluorine / Aromatic substitution / Mass spectrometry / Heterocycles / Quantum interference
The synthesis and characterization of seven tailor-made
highly fluorous porphyrin derivatives are described, as large
perfluoroalkyl-functionalized organic molecules are the most
complex objects for which the quantum wave nature has
been observed so far. We have found, in particular, that tet-
rakis(pentafluorophenyl)porphyrin is a suitable starting point
for a modular synthesis that is geared towards porphyrin de-
rivatives with many peripheral fluorous chains. This allows
us to tailor and optimize the sublimation features of these
compounds for molecule interferometry. We have analyzed
the evaporation process of one member of the series by de-
termining the enthalpy of evaporation, as the creation of a
sufficiently intense, slow molecular beam is crucial for quan-
tum interference experiments. We present the quantum
fringe pattern of a second member of the series, which we
could obtain in a Kapitza–Dirac–Talbot–Lau interferometer.
fluoroalkyl-functionalized molecules have high vapor pres-
sures relative to their molecular weights.[7,8] Their volatility
originates in their low polarizability and only small
van der Waals interactions between the fluorinated chains.
Additionally, these structures are chemically stabilized due
to the strength of the carbon–fluorine bond.
Recently, we observed the wave nature of very massive
perfluoroalkylated fullerenes and porphyrins.[9] These struc-
tures mark the new records in mass, linear extension, and
number of atoms in a quantum interference experiment.
Here, we present the details of the design, synthesis, and
thermal properties of highly fluorous tetraarylporphyrins,
as required for the quantum studies.
Introduction
The wave nature of complex particles belongs to the in-
triguing properties of quantum physics, and quantum inter-
ferometry with organic macromolecules currently contrib-
utes to the exploration of the frontiers of experimental
quantum mechanics. In relation to that, chemical function-
alization methods have recently gained great importance, as
they allow us to tailor the molecular properties, such as
mass, polarizability, and volatility to the needs of quantum
optics experiments. Successful de Broglie coherence experi-
ments with compounds such as tetraphenylporphyrin
(TPP),[1] the fullerenes C60 and C70,[2,3] fluorinated fullerene
C60F48,[1] and perfluoroalkyl-functionalized tetraphenyl-
methane,[4] oligophenylene ethynylene (OPE),[4] azobenz-
ene,[5] and triphenylphosphane[6] have successively increased
the complexity of interfering particles and gave insight into
the influence of molecular structural features on de Broglie
interference.
In earlier studies, perfluoroalkyl-substituted tetraaryl-
porphyrins were achieved by the arrangement of the por-
phyrin framework using fluorinated starting materials.[10]
An alternative approach is the derivatization of function-
alized tetraarylporphyrins by linking perfluoroalkylated
carboxylic acids to amino-functionalized TPP through an
amide bond.[11] In order to prepare a variety of molecular
weights, a modular approach to peripherally functionalized
TPPs was particularly appealing. Therefore the introduc-
tion of substituents to tetrakis(pentafluorophenyl)por-
phyrin (TPPF20) by nucleophilic aromatic substitution reac-
tions was chosen. It is known that the four para-fluorine
atoms of TPPF20 can be effectively substituted by nucleo-
philes. This para-fluorine substitution reaction in penta-
fluorophenyl moieties is not limited to porphyrin sys-
tems.[12–14] The first example for the fourfold substitution
reaction of TPPF20 with a nucleophile was reported by
Kadish et al.[15] Examples with non-fluorous alcohols,[16–18]
amines,[16,17] or thiols[16,19] as well as the introduction of
All these studies require free and slow molecular beams
that are presently created by thermal sublimation or evapo-
ration. The flying compounds must therefore exhibit both
a high thermal stability and a high vapor pressure. Previous
experiments indicated already that these requirements can
be well fulfilled for highly fluorinated compounds.[1,4–6] Per-
[a] Department of Chemistry, University of Basel,
St. Johannsring 19, 4056 Basel, Switzerland
Fax: +41-61-267-1016
E-mail: marcel.mayor@unibas.ch
[b] University of Vienna, Vienna Center for Quantum Science and
Technology, VCQ, Faculty of Physics,
Boltzmanngasse 5, 1090 Vienna, Austria
[c] Karlsruhe Institute of Technology (KIT),
Institute for Nanotechnology,
fluorous nucleophiles – namely alcohols[20] and thiols[21,22]
are also known.
–
P. O. Box 3640, 76021 Karlsruhe, Germany
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201100638.
Eur. J. Org. Chem. 2011, 4823–4833
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4823

J. Tüxen, S. Eibenberger, S. Gerlich, M. Arndt, M. Mayor
FULL PAPER
Synthetic Strategy
Results and Discussion
In order to be able to explore a large diversity of different
designs of the fluorous periphery, a modular synthetic con-
cept was pursued. As depicted in Scheme 1, the fluorous
outer parts of the porphyrin derivatives were introduced in
the last step of the reaction pathway, allowing easy modifi-
cation of these moieties. The key step on the way towards
all seven target structures is the nucleophilic aromatic sub-
stitution reaction to introduce the fluorous building blocks.
Both thiols and primary amines as nucleophiles usually give
substitution products in good to excellent yields.[12] Com-
mercially available fluorinated nucleophiles can be used for
the synthesis of porphyrins 1 and 2, allowing us to improve
the reaction conditions with purchased starting materials.
In all other cases, the building blocks were synthesized by
us prior to their attachment to the porphyrin center.
The synthesis of building blocks 9 and 10 starts with the
attachment of two perfluorinated alkyl chains to dibromide
13. Classical functional group transformation provides ac-
cess to thiol 9 and amine 10. It was anticipated that thiol
14 can be assembled from triflate 15, which is known to be
accessible in five steps from commercially available starting
materials.[23] The starting point for the synthesis of building
block 16 is tribromide 18. Monothiolation, introduction of
the fluorous ponytails in an SN2 reaction, and the deprotec-
tion step represent the pathway to building block 16. In the
reaction sequence towards thiol 19, alcohol 11 as fluorous
part is supposed to be attached to dibromide 17, the central
unit of the building block.
Molecular Design
In our present work seven fluorous porphyrins were syn-
thesized and investigated. They vary in their structural mo-
tifs of the fluorous periphery. The aim was to cover a spe-
cific mass range and to optimize the design of the structures
towards high volatility. As depicted in Figure 1, the amount
of fluorous chains ranges from four (i.e., 1 and 2) over eight
(i.e., 3–6) to 16 (i.e., 7). To the best of our knowledge, there
is only one example of a fluorous porphyrin derivative that
bears more than 16 fluorinated ponytails (24 chains) from
Bríza et al.[20] The length of the perfluoroalkyl parts was
ˇ
also varied. Compounds 1, 2, and 6 bear perfluorooctyl
chains, whereas the other structures comprise perfluo-
rohexyl chains. In order to investigate correlations between
the molecular structure and the thermal stability of the
compounds, the nature of the interlinking between the par-
ent tetraarylporphyrin and the fluorous substituents was
varied by introducing different heteroatoms as linkage. Our
series includes two amine-based and five thiol-derived por-
phyrins. Furthermore, the branching unit of derivatives 3–
7 was varied. In porphyrin 5, the branching occurs in an
aliphatic segment, whereas the other four branched struc-
tures comprise 1,3,5-trisubstituted benzenes.
Synthesis
As shown in Scheme 2, building blocks 9 and 10 com-
prise two perfluorohexyl chains that are directly attached
to the aromatic core. The reaction conditions for the intro-
duction of these chains have been previously reported for
the synthesis of a fluorinated oligophenylene ethynylene
(OPE).[4] In this first step, the fluorous ponytails were intro-
duced in a copper-mediated cross-coupling reaction of n-
perfluorohexyliodide and dibromide 13. The starting mate-
rial was heated together with freshly activated copper in
dimethylformamide (DMF) at 125 °C under an argon at-
mosphere for 12 h. Desired methyl ester 12 was isolated af-
ter purification by column chromatography (CC) as a white
solid in 91% yield. The reduction of ester 12 using lithium
aluminum hydride (LiAlH4) in diethyl ether at room tem-
perature led, after aqueous workup and purification by
recrystallization from hexane, to benzylic alcohol 11 as a
white solid in 90% yield. In order to convert benzylic
alcohol 11 into the corresponding benzylic thioacetate, a
modification[24] of the Mitsunobu reaction[25] was per-
formed. A mixture of alcohol 11 and thioacetic acid in
tetrahydrofuran (THF) was treated with a solution contain-
ing the preformed adduct of triphenylphosphane and di-
isopropyl azodicarboxylate (DIAD). The formation of the
betaine derived from triphenylphosphane and DIAD prior
to the addition of the alcohol and thioacetic acid is crucial
Figure 1. Highly fluorous porphyrin derivatives 1–7. The series co-
vers a molecular weight range from 2803 (2) to 7553 gmol–1 (7),
which is the current mass region of the most-complex interfering
particles.
4824
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 4823–4833

Fluorous Porphyrins as Model Compounds for Molecule Interferometry
Scheme 1. Synthetic strategy towards target compounds 1–7. A nucleophilic aromatic substitution reaction is the key step to the desired
porphyrin derivatives. The first step towards thiols 16 and 19 is the introduction of the sulfur functionality bearing a protecting group
(PG).
for the formation of the product. Pure acetylsulfanyl deriva-
For the synthesis of benzylic amine 10, the same strategy
tive 22 was obtained after CC as a colorless oil in a yield as for the benzylic thiol was envisaged. The nitrogen was –
of 61%. The final step towards building block 9 was the identical to the sulfur atom of building block 9 – introduced
deprotection of the acetyl-protected sulfur to obtain free in a Mitsunobu reaction.[25] DIAD was slowly added to a
thiol 9. Acidic cleavage of the protecting group was realized solution of alcohol 11, triphenylphosphane, and phthal-
by the in situ generation of hydrochloric acid. The addition imide in THF at –5 °C. The reaction mixture was stirred at
of acetyl chloride to a solution of thioacetate 22 in a solvent room temperature for 12 h. An aqueous workup and purifi-
mixture of methanol and dichloromethane (CH2Cl2) led to cation by CC afforded desired phthalimide derivative 23 as
the formation of the desired product. After a reaction time a white solid in a yield of 87%. Cleavage of the N-benzyl-
of five hours the crude product was purified by CC to af- phthalimide was achieved with the help of the Ing–Manske
ford 9 as a white solid in a yield of 72%.
procedure.[26] The benzylic amine was obtained by hydroly-
Eur. J. Org. Chem. 2011, 4823–4833
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4825

J. Tüxen, S. Eibenberger, S. Gerlich, M. Arndt, M. Mayor
FULL PAPER
The three-step synthesis towards building block 16 was
recently published by us.[9] First, a protected sulfur func-
tionality was introduced into tris(bromomethyl)benzene
(18). The two other bromides were subsequently substituted
by fluorous moieties and a final deprotection step led to
highly fluorous benzylic thiol 16 (Scheme 3). The same
strategy was pursued to assemble thiol 19. Alcohol 11 as
the fluorous part was attached to dibromide 17. Generation
of an alcoholate by the addition of alcohol 11 to a suspen-
sion of sodium hydride in THF and a subsequent SN2 reac-
tion of the alcoholate and dibromide 17 led to highly fluo-
rous trityl-protected thiol 26, which was isolated in a yield
of 67% after purification by CC. The final deprotection was
achieved in an analogous manner, as described for trityl
derivative 24, leading to thiol 19. Purification by CC af-
forded pure thiol 19 as a white solid in a yield of 72%.
All precursors were fully characterized by NMR spec-
troscopy (1H, 13C, and 19F), mass spectrometry, and ele-
mental analysis. With thiol dendrons 9, 14, 16, and 19 in
hand, the envisaged target porphyrins comprising several
peripheral fluorous ponytails became accessible. Table 1
gives an overview of the nucleophilic aromatic substitution
reactions carried out to assemble target structures 1, 3, 5,
6, and 7. The five sulfur-substituted porphyrin derivatives
were assembled in a similar way to that described by Sama-
roo et al. in the substitution reaction of TPPF20 (8) with
1H,1H,2H,2H-perfluorododecane-1-thiol. In their proto-
col, the porphyrin and the thiol are treated at room tem-
perature in a mixture of ethyl acetate and DMF with a di-
alkylamine derivative as base.[21,22] In all five cases, a solu-
tion of TPPF20 in DMF was added to a solution of the
thiol (i.e., 9, 14, 16, 19, or 20; 6.0–10.0 equiv.) and dieth-
ylamine in a mixture of ethyl acetate and DMF. Stirring at
room temperature for 1 to 6.5 h was followed by quenching
with water. Extraction with diethyl ether and a subsequent
wash with brine were followed by purification by CC.
For porphyrin derivative 1, recrystallization from acetone
or precipitation from an ethanol/acetone mixture was also
successfully applied as an alternative purification pro-
cedure. All five thiol-based target compounds were isolated
as intensely purple colored solids. The yield obtained for
derivative 1 bearing four perfluorooctyl moieties was 81%.
Compound 3 with eight perfluorohexyl chains was isolated
in a yield of 89%. Derivative 5, having eight perfluorooctyl
Scheme 2. Synthesis of the precursors 9, 10, and 14. Reagents and
conditions: (a) IC6F13, Cu, DMF, 125 °C, 12 h, 91%; (b) LiAlH4,
Et2O, r.t., 12 h, 90%; (c) DIAD, PPh3,THF, 0 °C, 2 h, then 11, thi-
olacetic acid, 0 °C to r.t., 3 h, 61%; (d) acetyl chloride, MeOH,
CH2Cl2, r.t., 5 h, 72%; (e) phthalimide, DIAD, PPh3,THF, –5 °C to
r.t., 12 h, 87%; (f) hydrazine hydrate, EtOH, toluene, reflux, 12 h,
quant.; (g) trityl thiol, NaH, THF, r.t., 2 h, 95%; (h) HSiEt3, TFA,
CH2Cl2, r.t., 25 min, 88%.
sis of compound 23 with hydrazine in a solvent mixture of
ethanol and toluene. After 12 h at reflux and an aqueous
workup, the free benzylic amine was isolated as a white so-
lid in quantitative yield with no need for further purifica-
tion.
Thiol 14 was synthesized in seven steps. Starting from 3-
(perfluorohexyl)propyl iodide and diethyl malonate, triflate
15 was assembled in five steps according to a literature pro-
cedure.[23] This literature protocol yields triflate 15 in a high
overall yield of 80% over the five steps including only two
purification steps. With the triflate in hand, the sulfur can
be efficiently introduced as a trityl-protected functionality
by the reaction of triflate 15 with trityl thiol and an excess
amount of sodium hydride stirred in THF at room tempera-
ture for two hours. Purification by CC led to desired com-
pound 24 as colorless oil in a yield of 95%. By following a
procedure developed by Moreau et al., the trityl protecting
group was removed under acidic conditions in the presence
of a cation scavenger.[27] Trifluoroacetic acid (TFA) was
added to a solution of protected thiol 24 and triethylsilane
(1.5 equiv.) in CH2Cl2. The deprotection reaction is fast,
even at low acid concentrations (4 vol.-% related to the
amount of CH2Cl2). After stirring for 25 min at room tem-
perature and an aqueous workup, free thiol 14 was obtained
after CC as a white solid in a yield of 88%.
Scheme 3. Synthesis of thiols 16 and 19. Reagents and conditions: (a) trityl thiol, K2CO3, THF, reflux, 20 h, 33%; (b) HO(CH2)3-
C8F17, NaH, THF, reflux, 4 h, 52%; (c) HSiEt3, TFA, CH2Cl2, r.t., 1 h, 77%; (d) 11, NaH, THF, reflux, 4 h, 67%; (e) HSiEt3, TFA,
CH2Cl2, r.t., 20 min, 72%.
4826
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 4823–4833

Fluorous Porphyrins as Model Compounds for Molecule Interferometry
Table 1. para-Fluorothiol substitution reactions towards target compounds 1, 3, 5, 6, and 7.
parts in its periphery, afforded a yield of 70%. Porphyrin 6 alized silica gel as stationary phase. Therefore the retention
with 8 and derivative 7 with 16 perfluorohexyl chains were time of molecules is primarily determined by their fluorine
obtained in a yield of 64 and 31%, respectively. For the content.[29] Fluorous HPLC is an ideal tool for the analysis
substitution of the para-fluoro groups by primary amines of porphyrins 1–6, as the side products of the nucleophilic
21 and 9 a slightly modified method developed by Samaroo aromatic substitution reactions, mainly three- or fivefold
et al.[28] using microwave irradiation and N-methylpyrrol- substituted derivatives, can be easily distinguished due to
idone (NMP) as solvent was applied (Scheme 4). A mixture their different fluorine content. For example, the retention
of TPPF20 and 10 equivalents of the amine (i.e., 9 or 21) in times of porphyrin 5 and the major side product of the final
NMP was heated in a microwave apparatus at 250 °C for reaction step, which is the threefold substituted derivative,
two hours. The reaction time was optimized by checking are 7.50 min for the product and 2.58 min for the impurity
the conversion after several reaction times (3, 20, 90, and on a FluoroFlash column (50 mm, 1.4 mLmin–1, 100%
120 min) by thin-layer chromatography. Quenching with THF, 50 °C). However, porphyrin 7 was not eluted under
water and extraction with diethyl ether yielded the crude the conditions we tested. We hypothesize that the interac-
product, which was purified by CC. Porphyrin derivatives 2 tions between the stationary phase and porphyrin 7 bearing
and 4 were obtained as intensely purple colored solids in a 16 perfluorohexyl chains are too strong and thus prevent
yield of 75 and 50%, respectively.
elution. The purity of this derivative can be seen in the
The purities of porphyrin derivatives 1–6 were monitored chromatogram of the recycling gel permeations chromatog-
by analytical HPLC on a fluorous column (FluoroFlash). raphy that was used to purify this compound (see Support-
These columns are packed with perfluorooctyl-function- ing Information for HPLC and GPC chromatograms).
Eur. J. Org. Chem. 2011, 4823–4833
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4827

J. Tüxen, S. Eibenberger, S. Gerlich, M. Arndt, M. Mayor
FULL PAPER
the measurement, an effusive molecular beam is generated
in a resistively heated ceramic furnace. A signal pro-
portional to the temperature-dependent molecular vapor
pressure is recorded in an electron impact quadrupole mass
spectrometer (QMS) about 2.5 m behind the source.[30] The
signal is attenuated by the gratings of a matter-wave inter-
ferometer that is inserted between the source and the detec-
tor for the purpose explained below but is of no relevance
for the volatilization experiments.
The enthalpy of evaporation ΔHvap can be determined
by recording the QMS counting signal N at the given mass
as a function of the source temperature T. Based on an
adapted Clausius–Clapeyron equation we expect the follow-
ing relation to hold: ln(NT) = –(ΔHvap) ⁄ RT – const, with
R = 8.314 Jmol–1 K–1. This includes the exponential tem-
perature dependence of the vapor pressure and assumes a
hydrodynamic flow from the thermal source.[31] Figure 2
shows the measured QMS signal at the mass of porphyrin
1 (m = 2815 gmol–1). We have conducted three independent
measurements, of which one is given by the black triangles.
A linear fit to ln(NT) as a function of 1/T is shown as a
solid line, and its slope b allows us to determine the molecu-
lar enthalpy of evaporation ΔHvap = –bR. Its mean value
between 543 and 590 K is 298(34) kJmol–1, where we only
denote the statistical uncertainty of three independent mea-
surements. The temperature uncertainty is estimated to be
10 K on an absolute scale, but rather 2 K on a relative scale.
Scheme 4. Synthesis of target compounds 2 and 4. Reagents and
conditions: (a) NMP, microwave irradiation, 250 °C, 2 h, 75%;
(b) NMP, microwave irradiation, 250 °C, 2 h, 50%.
Furthermore, the porphyrins were characterized by
NMR spectroscopy (1H and 19F), mass spectrometry
(MALDI-ToF), and UV/Vis spectroscopy. The mass spectra
of all target compounds show exclusively the molecule ion
peak [M]+. The absence of the peak for the threefold substi-
tuted porphyrin corroborates that only the desired fourfold
1
substituted derivatives were isolated. From the 19F and H
NMR spectra it is furthermore evident that the four substit-
uents are attached exclusively in the para positions of the
four fluorinated phenyl rings. A singlet for the eight pyrrole
1
protons of the porphyrin core in the H NMR spectrum
and two distinct signals for the aromatic fluorine atoms
corroborate the expected para substitution pattern. The ab-
sorption spectra of the porphyrins in CH2Cl2 at room tem-
perature show the expected bands (see Supporting Infor-
mation for UV/Vis spectra). For all derivatives, a very in-
tense Soret band at 415–420 nm and three Q bands at 508–
510, 536–537, and 584–586 nm were observed.
Remarkably, all fluorous porphyrins remain perfectly
processable with common techniques in organic synthesis
in spite of their high fluorine content. No fluorinated sol-
vents were necessary to synthesize, purify, or characterize
the target compounds, as they are all soluble in common
organic solvents including acetone, chloroform, and ethers
(diethyl ether and THF).
Figure 2. The detected molecular beam intensity of 1 reveals the
expected exponential dependence as a function of the temperature.
The triangles represent the data for one out of three independent
experiments with different batches produced by the same synthesis.
The solid line is a linear fit to the data. We show here only one of
three data sets used for the extraction of the enthalpy value.
Suitability for Quantum Interference Experiments
Thermal Investigations
Molecules as synthesized in our present work can be use-
The generation of free molecular beams is a prerequisite ful for a number of modern quantum optics experiments
for successful quantum experiments with our interferome- that rely on the availability of massive, slow, mass-selected
ters. Therefore, we analyzed this process by determining the compounds that can be volatilized in abundant quantities.
enthalpy of evaporation exemplarily for porphyrin 1. For This comprises explorations of quantum interferometry, the
4828
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 4823–4833

Fluorous Porphyrins as Model Compounds for Molecule Interferometry
Figure 3. Sketch of the experimental setup. The powder is evaporated in the oven, the molecules fly through three subsequent gratings,
G1, G2, and G3, in our interferometer, and are detected in an electron impact quadrupole mass spectrometer (QMS).
development of new beam splitters for molecules and optics and leads to a local change in the molecular potential en-
elements in general, as well as prospects for off-resonant ergy in proportion to ΔW ϰ αoptE2(x,z)/2. The standing
cavity-assisted cooling schemes[32] We illustrate this here for light wave imposes E2 ϰ sin 2kz, where k = 2π/λ is the wave
the example of matter-wave interferometry of porphyrin 2, vector of the laser field.
which is already significantly more complex than other vol-
In the course of its propagation, the phase modulated
atile compounds that can be obtained commercially.
molecular matter wave of mass m and velocity v, corre-
The powder was synthesized following the steps de- sponding to a de Broglie wavelength λdB = h/mv generates
scribed above and evaporated at T ≈ 580 K. The molecular a modulation of the molecular density further downstream,
beam follows the same trajectory as in the earlier evapora- which is most pronounced close to multiples of the Talbot
tion experiments: It starts out in the oven, passes a series length, LT = d2/λdB. This density pattern can be visualized
of delimiters determining the maximal height of the beam, by placing the grating G3 in this distance and by scanning
flies through three subsequent gratings in our interferome- it across the molecular beam. Quantum theory predicts for
ter, and finally enters an electron impact quadrupole mass our experimental boundary conditions that a sizeable and
spectrometer (Figure 3).
periodic density variation can only be expected if the mole-
The idea of molecular matter-wave interference is similar cules delocalize over several hundred nanometers. Formal
to Young’s famous double slit experiment and aims at dem- details of the Kapitza–Dirac–Talbot–Lau interferometer
onstrating the quantum nature of hot, massive molecules are given in Hornberger et al.[33] In Figure 4 we show this
composed of more than one hundred atoms and delocalized density modulation, that is, the quantum interference
over more than one hundred times their own size. The mo- fringes, for porphyrin 2, which here achieves a visibility of
lecular complexity entails that the matter-wave phases be- V = (Imax – Imin)⁄(Imax + Imin) = 24(3)%, where Imax and
tween different molecules are all scrambled in a thermal Imin are the maximum and minimum intensity of the molec-
source. Experiments similar to classical light wave optics ular QMS signal upon translation of the third grating G3.
interference are however possible if we provide a small ef-
fective source size and a sufficiently small wavelength distri-
bution.
In our Kapitza–Dirac–Talbot–Lau interferometer the
source size is confined by the first of three gratings G1,
which is an array of slits with a period of d = 266 nm and
an opening of 90 nm width. This mask confines the possible
positions of the impinging molecules and prepares what
may be best described as an array of Huygen’s wavelets, in
analogy to light wave optics. Since none of the matter wave-
lets has a well-defined relation to any of the neighboring
waves this does not yet suffice to see quantum interference.
The emergent wavelets do, however, expand behind G1 and
finally cover two or more slits in grating G2, 105 mm further
downstream. G2 has the same period as G1 but it is not
made of matter. Instead, it is a phase mask realized by ret-
roreflecting a green laser beam at a plane mirror perpendic-
ular to the molecular beam. The electric field E of the
standing light wave induces an oscillating electric dipole
oidal fit to the data. The shaded area represents the dark rate in the
moment in the molecules with an optical polarizability αopt detector. An interference fringe visibility of 24(3)% was observed.
Figure 4. Quantum interference pattern for porphyrin 2. The black
dots represent the experimental result, and the solid line is a sinus-
Eur. J. Org. Chem. 2011, 4823–4833
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4829

J. Tüxen, S. Eibenberger, S. Gerlich, M. Arndt, M. Mayor
FULL PAPER
(7.43 g, 117 mmol, 6.0 equiv.) in acetone (20 mL). After 15 min the
liquid phase was eliminated, and the copper was washed with hy-
drochloric acid in acetone, followed by acetone alone. The activated
Conclusions
We have presented a modular synthesis of seven perfluo-
roalkyl-substituted porphyrin derivatives with up to 16
fluorous alkyl chains as model compounds for molecular
interferometry experiments. To meet the requirements of
quantum studies with complex organic molecules – high
volatility, high stability, and high molecular mass – we
choose the functionalization of tetraarylporphyrins with
perfluoroalkyl moieties. Our work shows that the design cri-
teria for thermal evaporation and stability are fulfilled at
least for the first members of this series. In particular, a
reliable sublimation curve up to 600 K is recorded for por-
phyrin 1. Quantum interference experiments were recorded
with thermal beams obtained by sublimation of derivative
2. It showed unambiguous mass peaks in electron impact
ionization quadrupole mass spectrometry and also high
contrast quantum interference in a modern implementation
of matter-wave interferometry. Furthermore, quantum in-
terference with porphyrins 1 and 6 were already reported
elsewhere.[9] Currently, we are exploring the mass limit of
sublimable organic dyes with tailor-made series based on
the modular synthetic approach described in the paper.
copper
and
methyl-3,5-dibromo-4-methylbenzoate
(6.00 g,
19.5 mmol, 1.0 equiv.) were added to dry DMF (50 mL) under an
argon atmosphere. The suspension was heated whilst stirring to
95 °C and n-perfluorohexyliodide (16.9 mL, 34.8 g, 77.9 mmol,
4.0 equiv.) was then added dropwise to the suspension over 45 min.
After stirring overnight at 125 °C, the mixture was cooled to room
temperature, diluted with water and diethyl ether, and filtered
through a Celite plug. The solid residue was washed with diethyl
ether. The aqueous phase was extracted with diethyl ether. The
combined organic layers were washed with brine and dried with
magnesium sulfate. After evaporating the solvent, the pale yellow
crude was purified by CC (silica gel; ethyl acetate/hexane, 1:4) to
give methyl 4-methyl-3,5-bis(perfluorohexyl)benzoate (13.9 g) as a
white solid in a yield of 91%. 1H NMR (400 MHz, CDCl3): δ =
8.42 (s, 2 H, Ar-H), 3.99 (s, 3 H, COOCH3), 2.63 (s, 3 H, Ar-
CH3) ppm. 19F NMR (376 MHz, CDCl3): δ = –81.9 (t, J = 10 Hz,
6 F, CF3), –104.6 (m, 4 F, CF2), –121.0 (m, 4 F, CF2), –122.7 (m,
4 F, CF2), –123.8 (m, 4 F, CF2), –127.2 (m, 4 F, CF2) ppm. 13C
NMR (101 MHz, CDCl3): δ = 164.6, 144.5, 133.6 (t, 3JCF = 10 Hz),
2
130.5 (t, JCF = 22 Hz), 128.8, 52.9, 16.6 ppm. MS (EI): m/z (%) =
786 (6) [M]+, 755 (45), 517 (100). C21H8F26O2 (786.24): calcd. C
32.08, H 1.03; found C 32.12, H 1.00.
4-Methyl-3,5-bis(perfluorohexyl)benzylic Alcohol (11): A solution of
ester 12 (10.3 g, 13.1 mmol, 1.0 equiv.) in diethyl ether (125 mL)
was added dropwise to a suspension of lithium aluminum hydride
(746 mg, 19.7 mmol, 1.5 equiv.) in diethyl ether (50 mL). This mix-
ture was stirred at room temperature under an atmosphere of argon
for 12 h, before ethyl acetate (4 mL) was added. After 15 min, an
aqueous sulfuric acid solution (10%, 10 mL) was slowly added to
the stirred reaction mixture, which was then stirred for another
10 min. The organic phase was removed, and the aqueous phase
was extracted with diethyl ether. The combined organic layers were
washed with brine and dried with magnesium sulfate. Evaporation
of the solvent afforded a pale yellow solid that was recrystallized
from hexane to give pure 11 (8.97 g) as a white solid in a yield of
Experimental Section
General Remarks: All commercially available starting materials
were of reagent grade and used as received. Tetrakis(pentafluoro-
phenyl)porphyrin was purchased from Sigma–Aldrich and used as
received. Dry THF, dry DMF, and dry CH2Cl2 were purchased
from Fluka, stored over 4 Å molecular sieves, and handled under
an atmosphere of argon. The solvents for column chromatography
and extraction were of technical grade and distilled prior to use.
The solvent for HPLC analyses was of HPLC grade. Column
chromatography purifications were carried out on silica gel 60 (par-
ticle size 0.040–0.063 mm) from Fluka. 1H, 19F, and 13C NMR
spectra were recorded with a Bruker DMX 400 instrument (1H
resonance 400 MHz) or a Bruker DRX 500 instrument (1H reso-
nance 500 MHz) at 298 K. In the 13C NMR spectra the signals of
the perfluoroalkyl segments were not assigned due to the coupling
to fluorine. Deuterated solvents were purchased from Cambridge
Isotope Laboratories. UV/Vis spectra were recorded with a UV-
1800 spectrophotometer from Shimadzu. Matrix-Assisted laser de-
sorption ionization time of flight (MALDI-ToF) mass spectra were
performed with an Applied Bio Systems Voyager-De Pro mass
spectrometer. ESI-TOF mass spectra were recorded with a Bruker
MicrOTOFQ instrument. Electron impact (EI) mass spectra were
recorded with a Finnigan MAT 95Q. Fast atom bombardment
(FAB) mass spectra were recorded with a Finnigan MAT 8400.
Elemental analyses were performed with a Perkin–Elmer Analys-
ator 240. Analytical HPLC was performed with an Agilent HPLC
system (series 1100) using a FluoroFlash HPLC column (4.6 mm
i.d., 50 mm length, 5 μm) from Fluorous Technologies Inc. Micro-
wave reactions were carried out with an Initiator 8 (400 W) from
Biotage. Gel permeations chromatography (GPC) was performed
with a Shimadzu Prominence System with PSS SDV preparative
columns from PSS (2 columns in series: 600 mmϫ20.0 mm,
5 μm particles, linear porosity “S”, operating ranges: 100–
100 000 gmol–1) using chloroform as eluent.
1
90%. H NMR (400 MHz, CDCl3): δ = 7.77 (s, 2 H, Ar-H), 4.81
3
3
(d, JHH = 5.8 Hz, 2 H, CH2), 2.55 (s, 3 H, CH3), 1.85 (t, JHH
=
5.8 Hz, 1 H, OH) ppm. 19F NMR (376 MHz, CDCl3): δ = –81.9
(t, J = 10 Hz, 6 F, CF3), –104.5 (m, 4 F, CF2), –121.1 (m, 4 F, CF2),
–122.8 (m, 4 F, CF2), –123.8 (m, 4 F, CF2), –127.2 (m, 4 F,
CF2) ppm. 13C NMR (101 MHz, [D6]acetone): δ = 143.9, 138.9,
3
2
132.6 (t, JCF = 10 Hz), 130.8 (t, JCF = 21 Hz), 63.9, 17.2 ppm.
MS (EI): m/z (%) = 758 (16) [M]+, 489 (100), 439 (30). C20H8F26O
(758.23): calcd. C 31.68, H 1.06; found C 31.47, H 1.04.
4-Methyl-3,5-bis(perfluorohexyl)benzyl Thioacetate (22): Tri-
phenylphosphane (1.73 g, 6.59 mmol, 2.0 equiv.) and DIAD
(1.29 mL, 1.33 g, 6.59 mmol, 2.0 equiv.) were dissolved in dry THF
(25 mL) under an argon atmosphere at 0 °C. This solution was
stirred at 0 °C for 2 h before a solution of benzylic alcohol 11
(2.50 g, 3.30 mmol, 1.0 equiv.) and thiolacetic acid (469 μL,
502 mg, 6.59 mmol, 2.0 equiv.) in dry THF (25 mL) was added. The
reaction mixture was stirred for 1.5 h at 0 °C followed by 1.5 h at
room temperature. After evaporation of the solvent the crude was
purified by CC (silica gel; ethyl acetate/cyclohexane, 1:20) to give
pure 22 (1.65 g) as a colorless oil in a yield of 61%. 1H NMR
(400 MHz, CDCl3): δ = 7.69 (s, 2 H, Ar-H), 4.14 (s, 2 H, CH2),
2.52 (s, 3 H, Ar-CH3), 2.37 (s, 3 H, SCOCH3) ppm. 19F NMR
(376 MHz, CDCl3): δ = –81.0 (t, J = 10 Hz, 6 F, CF3), –103.7 (m,
4 F, CF2), –120.3 (m, 4 F, CF2), –121.9 (m, 4 F, CF2), –122.9 (m,
4 F, CF2), –126.3 (m, 4 F, CF2) ppm. 13C NMR (126 MHz, CDCl3):
Methyl 4-Methyl-3,5-bis(perfluorohexyl)benzoate (12): Whilst stir-
ring, a few crystals of iodine were added to a suspension of copper
4830
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 4823–4833

Fluorous Porphyrins as Model Compounds for Molecule Interferometry
3
2
δ = 194.3, 138.3, 136.6, 132.9 (t, JCF = 10 Hz), 130.0 (t, JCF
=
2.6 equiv.) and 17 (250 mg, 453 μmol, 1.0 equiv.) were dissolved in
dry THF (20 mL) under an atmosphere of argon. Sodium hydride
(60% dispersion in mineral oil, 108 mg, 2.72 mmol, 6.0 equiv.) was
added, and the reaction mixture was stirred for 4 h at reflux. After
cooling to room temperature, it was quenched with a saturated
aqueous ammonium chloride solution. The mixture was extracted
with diethyl ether, and the organic fractions were washed with
brine, dried with magnesium sulfate, filtered, and concentrated to
dryness. Purification by CC (silica gel; hexane/acetone, 12:1) gave
the title compound (580 mg) as a colorless oil in a yield of 67%.
1H NMR (400 MHz, CDCl3): δ = 7.72 (s, 4 H, Ar-H), 7.47–7.44
(m, 6 H, Ar-Hortho of trityl group), 7.31–7.26 (m, 6 H, Ar-Hmeta of
trityl group), 7.23–7.19 (m, 3 H, Ar-Hpara of trityl group), 7.18 (s,
1 H, Ar-H), 7.05 (s, 2 H, Ar-H), 4.56 (s, 4 H, CH2), 4.52 (s, 4 H,
CH2) 3.33 (s, 2 H, ArCH2STrt), 2.53 (s, 6 H, CH3) ppm. 19F NMR
(376 MHz, CDCl3): δ = –81.1 (t, J = 10 Hz, 12 F, CF3), –103.6 (m,
8 F, CF2), –120.3 (m, 8 F, CF2), –122.0 (m, 8 F, CF2), –123.0 (m,
8 F, CF2), –126.4 (m, 8 F, CF2) ppm. 13C NMR (126 MHz, CDCl3):
δ = 144.8, 138.7, 138.4, 138.2, 137.0, 131.6 (t, 3JCF = 10 Hz), 130.0
(t, 2JCF = 22 Hz), 129.8, 128.4, 128.1, 126.9, 126.1, 72.5, 70.7, 67.7,
36.9, 16.0 ppm. MS (ESI-Q-ToF): m/z (%) = 1929 (89) [M + Na]+,
686 (100). C68H38F52O2S (1907.00): calcd. C 42.83, H 2.01; found
C 43.11, H 2.16.
21 Hz), 32.4, 30.3, 15.9 ppm. MS (EI): m/z (%) = 816 (4) [M]+, 741
(26). C22H10F26OS (816.33): calcd. C 32.37, H 1.23; found C 32.41,
H 1.29.
4-Methyl-3,5-bis(perfluorohexyl)benzylthiol (9): Compound 22
(270 mg, 331 μmol, 1.0 equiv.) was dissolved in a mixture of
CH2Cl2 (5 mL) and methanol (10 mL). The mixture was degassed
by purging argon through the solution for 10 min. Acetyl chloride
(2.5 mL) was added in portions of 0.5 mL every hour. After a reac-
tion time of 5 h the solvent was evaporated. The crude was purified
by CC (silica gel; CH2Cl2/cyclohexane, 1:6) to give pure 9 (184 mg)
1
as a white solid in a yield of 72%. H NMR (400 MHz, CDCl3): δ
3
= 7.73 (s, 2 H, Ar-H), 3.81 (d, JHH = 7.9 Hz, 2 H, CH2), 2.53 (s,
3 H, CH3), 1.83 (t, JHH = 7.9 Hz, 1 H, SH) ppm. 19F NMR
3
(376 MHz, CDCl3): δ = –81.0 (t, J = 10 Hz, 6 F, CF3), –103.7 (m,
4 F, CF2), –120.3 (m, 4 F, CF2), –121.9 (m, 4 F, CF2), –122.9 (m,
4 F, CF2), –126.3 (m, 4 F, CF2) ppm. 13C NMR (126 MHz, CDCl3):
δ = 139.6, 138.1, 132.2 (t, JCF = 10 Hz), 130.0 (t, JCF = 22 Hz),
28.0, 15.9 ppm. MS (EI): m/z (%) = 774 (9) [M]+, 741 (100).
C20H8F26S (774.29): calcd. C 31.02, H 1.04; found C 31.04, H 1.15.
3
2
N-[4-Methyl-3,5-bis(perfluorohexyl)benzyl]phthalimide
(23):
A
solution of DIAD (587 μL, 603 mg, 2.98 mmol, 1.2 equiv.) in dry
THF (10 mL) was added dropwise to a solution of alcohol 11
(1.88 g, 2.48 mmol, 1.0 equiv.), phthalimide (439 mg, 2.98 mmol,
1.2 equiv.), and triphenylphosphane (782 mg, 2.98 mmol,
1.2 equiv.) in THF (20 mL) at –5 °C. This mixture was stirred at
room temperature under an atmosphere of argon for 12 h. After
evaporating the solvent the residue was dissolved in diethyl ether
and washed with an aqueous sodium hydroxide solution (1 m). The
organic layer was washed with brine and dried with magnesium
sulfate. Evaporation of the solvent and purification by CC (silica
gel; ethyl acetate/hexane, 1:2) afforded product 23 (1.91 g) as a
white solid in a yield of 87%. 1H NMR (400 MHz, CDCl3): δ =
7.85–7.82 (m, 4 H, Ar-H), 7.75 –7.72 (m, 2 H, Ar-H), 4.90 (s, 2 H,
CH2), 2.51 (s, 3 H, CH3) ppm. 19F NMR (376 MHz, CDCl3): δ =
–81.9 (t, J = 10 Hz, 6 F, CF3), –104.5 (m, 4 F, CF2), –121.2 (m, 4
F, CF2), –122.8 (m, 4 F, CF2), –123.8 (m, 4 F, CF2), –127.2 (m, 4
F, CF2) ppm. 13C NMR (101 MHz, CDCl3): δ = 167.7, 139.1,
134.8, 134.3, 133.1 (t, 3JCF = 10 Hz), 131.9, 130.2 (t, 2JCF = 22 Hz),
123.7, 40.7, 16.0 ppm. MS (EI): m/z (%) = 887 (100) [M]+, 618 (42),
568 (57). C28H11F26NO2 (887.35): calcd. C 37.90, H 1.25, N 1.58;
found C 37.85, H 1.26, N 1.54.
[3,5-Bis({[4-methyl-3,5-bis(perfluorohexyl)benzyl]oxy}methyl)-
phenyl]methanethiol (19): Compound 26 (675 mg, 0.35 mmol,
1.0 equiv.) and triethylsilane (86 μL, 62 mg, 0.53 mmol, 1.5 equiv.)
were dissolved in dry CH2Cl2 (25 mL). Trifluoroacetic acid
(1.0 mL) was added dropwise, and the reaction mixture was stirred
for 20 min at room temperature. The reaction was quenched by
the addition of a saturated aqueous solution of sodium hydrogen
carbonate. After completion of the gas formation, the phases were
separated, and the aqueous phase was extracted with CH2Cl2. The
combined organic fractions were dried with magnesium sulfate, fil-
tered, and concentrated to dryness. After purification by CC (silica
gel; hexane/CH2Cl2, 2:1), thiol 19 (425 mg) was obtained as a white
1
solid in a yield of 72%. H NMR (500 MHz, CDCl3): δ = 7.75 (s,
4 H, Ar-H), 7.28 (s, 2 H, Ar-H), 7.22 (s, 1 H, Ar-H), 4.61 (s, 4 H,
CH2), 4.57 (s, 4 H, CH2), 3.74 (d, 3JHH = 7.7 Hz, 2 H, Ar-CH2SH),
2.54 (s, 6 H, CH3), 1.76 (t, 3JHH = 7.7 Hz, 1 H, SH) ppm. 19F NMR
(376 MHz, CDCl3): δ = –81.1 (t, J = 10 Hz, 12 F, CF3), –103.6 (m,
8 F, CF2), –120.3 (m, 8 F, CF2), –121.9 (m, 8 F, CF2), –123.0 (m,
8 F, CF2), –126.4 (m, 8 F, CF2) ppm. 13C NMR (126 MHz, CDCl3):
3
δ = 142.0, 138.6, 138.5, 136.8, 131.5 (t, JCF = 10 Hz), 129.8 (t,
2JCF = 22 Hz), 127.1, 125.9, 72.3, 70.6, 28.7, 15.9 ppm. MS (ESI-
Q-ToF): m/z (%) = 1687 (100) [M + Na]+. C49H24F52O2S (1664.68):
calcd. C 35.35, H 1.45; found C 35.26, H 1.54.
4-Methyl-3,5-bis(perfluorohexyl)benzylamine (10): A solution of 23
(2.00 g, 2.25 mmol, 1.0 equiv.) and hydrazine hydrate (1.0 mL) in a
solvent mixture of ethanol (20 mL) and toluene (20 mL) was stirred
at reflux under argon overnight. After addition of CH2Cl2, the re-
action mixture was washed with an aqueous sodium hydroxide
solution (1 m). The aqueous phase was extracted with CH2Cl2, and
the combined organic layers were washed with brine and dried with
magnesium sulfate. After evaporation of the solvent, amine 10
(1.71 g) was obtained as a white solid in quantitative yield. 1H
NMR (400 MHz, CDCl3): δ = 7.74 (s, 2 H, Ar-H), 3.98 (s, 2 H,
CH2), 2.52 (s, 3 H, CH3), 1.47 (br. s, 2 H, NH2) ppm. 19F NMR
(376 MHz, CDCl3): δ = –81.9 (t, J = 10 Hz, 6 F, CF3), –104.4 (m,
4 F, CF2), –121.2 (m, 4 F, CF2), –122.8 (m, 4 F, CF2), –123.9 (m,
4 F, CF2), –127.3 (m, 4 F, CF2) ppm. 13C NMR (101 MHz, CDCl3):
1,7-Diperfluorohexyl-4-[(tritylthio)methyl]heptane (24): Triflate 15
(1.00 g, 1.11 mmol, 1.0 equiv.) and trityl thiol (492 mg, 1.78 mmol,
1.6 equiv.) were dissolved in dry THF (15 mL) under an atmo-
sphere of argon. To this solution was added sodium hydride (60%
dispersion in mineral oil, 178 mg, 4.45 mmol, 4.0 equiv.) at room
temperature. The reaction mixture was stirred for 2 h at room tem-
perature. After quenching with water, it was extracted with CH2Cl2.
The combined organic phases were washed with brine, dried with
magnesium sulfate, filtered, and concentrated to dryness. Purifica-
tion by CC (silica gel; cyclohexane/CH2Cl2, 4:1) gave title com-
pound 24 (1.08 g) as a colorless oil in a yield of 95%. 1H NMR
(500 MHz, CDCl3): δ = 7.44–7.40 (m, 6 H, Ar-Hortho of trityl
group), 7.30–7.26 (m, 6 H, Ar-Hmeta of trityl group), 7.23–7.19 (m,
3 H, Ar-Hpara of trityl group), 2.16–2.14 (m, 2 H, CH2STrt), 2.03–
1.89 (m, 4 H, CH2CF2), 1.44–1.24 (m, 9 H) ppm. 19F NMR
(376 MHz, CDCl3): δ = –81.0 (t, J = 10 Hz, 6 F, CF3), –114.5 (m,
4 F, CF2), –122.3 (m, 4 F, CF2), –123.1 (m, 4 F, CF2), –123.8 (m,
3
2
δ = 141.4, 137.6, 131.2 (t, JCF = 9 Hz), 129.7 (t, JCF = 22 Hz),
45.3, 15.8 ppm. MS (FAB): m/z (%) = 758 (100) [M + H]+, 741
(63). C20H9F26N (757.25): calcd. C 31.72, H 1.20, N 1.85; found C
32.19, H 1.36, N 1.88.
[3,5-Bis({[4-methyl-3,5-bis(perfluorohexyl)benzyl]oxy}methyl)-
benzyl](trityl)sulfane (26): Alcohol 11 (892 mg, 1.88 mmol,
Eur. J. Org. Chem. 2011, 4823–4833
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4831

J. Tüxen, S. Eibenberger, S. Gerlich, M. Arndt, M. Mayor
FULL PAPER
4 F, CF2), –126.4 (m, 4 F, CF2) ppm. 13C NMR (126 MHz, CDCl3): F, Ar-F), –160.0 (m, 8 F, Ar-F) ppm. MS (MALDI-ToF): m/z (%) =
δ = 144.7, 129.6, 127.9, 126.7, 66.7, 37.7, 35.3, 32.7, 31.0, 17.3 ppm.
MS (ESI-Q-ToF): m/z (%) = 1047 (100) [M + Na]+. C39H30F26S
(1024.67): calcd. C 45.71, H 2.95; found C 45.66, H 2.85.
3922 (100) [M]+. HPLC (FluoroFlash; 1.4 mLmin–1; 24 bar; 100%
THF; 50 °C): tR = 6.63 min (97.1%). UV/Vis (CH2Cl2): λ = 419,
510, 542, 586 nm.
5,10,15,20-Tetrakis[4-(2-perfluorooctylethylthio)-2,3,5,6-tetra-
fluorophenyl]porphyrin (1): The synthetic protocols and analytical
data (1H NMR, 19F NMR, mass spectra, and UV/Vis spectra) were
already reported.[9] HPLC (FluoroFlash; 1.4 mL min–1; 24 bar;
100% THF; 50 °C): tR = 1.82 min (97.6%).
1,7-Diperfluorohexyl-4-[(hydrothio)methyl]heptane (14): Protected
thiol 24 (1.00 g, 976 μmol, 1.0 equiv.) and triethylsilane (236 μL,
170 mg, 1.46 mmol, 1.5 equiv.) were dissolved in dry CH2Cl2
(20 mL) under an atmosphere of argon. Trifluoroacetic acid
(800 μL) was added dropwise, and the reaction mixture was stirred
for 25 min at room temperature. The reaction was quenched by
the addition of a saturated aqueous solution of sodium hydrogen
carbonate. After completion of the gas formation, the phases were
separated, and the aqueous phase was extracted with CH2Cl2. The
combined organic fractions were dried with magnesium sulfate, fil-
tered, and concentrated to dryness. After purification by CC (silica
gel; cyclohexane/CH2Cl2, 4:1), thiol 14 (669 mg) was obtained as a
5,10,15,20-Tetrakis[4-({3,5-bis[(3-perfluorooctylpropoxy)methyl]-
phenyl}methanethio)-2,3,5,6-tetrafluorophenyl]porphyrin (6): The
synthetic protocols and analytical data (1H NMR, 19F NMR, mass
spectra, and UV/Vis spectra) were already reported.[9] HPLC
(FluoroFlash; 1.4 mL min–1; 24 bar; 100 % THF; 50 °C): tR
=
21.70 min (97.6%).
1
colorless oil in a yield of 88%. H NMR (500 MHz, CDCl3): δ =
General Procedure for the Synthesis of Compounds 3, 5, and 7: The
thiol was added under an atmosphere of argon to a mixture of
ethyl acetate and DMF. To this solution was added diethylamine
and a solution of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin
in DMF. The reaction mixture was stirred under an atmosphere of
argon at room temperature and was then quenched by the addition
of water and subsequently diluted with diethyl ether. After phase
separation, the aqueous phase was extracted with diethyl ether. The
combined organic phases were washed with brine and the solvents
were evaporated to dryness. The crude was purified by CC (silica
gel, hexane/acetone) to give the desired compounds.
2.61–2.56 (m, 2 H, CH2SH), 2.13–2.03 (m, 4 H, CH2CF2), 1.67–
3
1.37 (m, 9 H), 1.21 (t, JHH = 8.1 Hz, 1 H, SH) ppm. 19F NMR
(376 MHz, CDCl3): δ = –81.0 (t, J = 10 Hz, 6 F, CF3), –114.5 (m,
4 F, CF2), –122.2 (m, 4 F, CF2), –123.1 (m, 4 F, CF2), –123.8 (m,
4 F, CF2), –126.4 (m, 4 F, CF2) ppm. 13C NMR (126 MHz, CDCl3):
δ = 39.8, 31.7, 31.1 (t, 2JCF = 22 Hz), 27.9, 17.5 ppm. MS (EI): m/z
(%) = 782 (3) [M]+, 389 (87), 375 (100). C20H16F26S (782.35): calcd.
C 30.70, H 2.06; found C 31.04, H 2.24.
5,10,15,20-Tetrakis[4-(3-perfluorooctylpropylamino)-2,3,5,6-tetra-
fluorophenyl]porphyrin (2): 5,10,15,20-Tetrakis(pentafluorophenyl)-
porphyrin (100 mg, 103 μmol, 1.0 equiv.) and 3-(perfluorooctyl)-
propylamine (490 mg, 1.03 mmol, 10.0 equiv.) were added to a mi-
crowave vial (Biotage microwave vial 10–20 mL). The mixture was
dissolved in NMP (10 mL), and the sealed tube was heated in a
microwave apparatus (Biotage, Initiator 8) to 250 °C for 2 h. After
cooling to room temperature the reaction mixture was diluted with
diethyl ether and water. The organic phase was separated and
washed with brine. After evaporation of the solvent under reduced
pressure, the crude was purified by CC (silica gel; acetone/hexane,
1:9 then 1:6) to afford desired compound 2 (214 mg) as a purple
5,10,15,20-Tetrakis{4-[4-methyl-3,5-bis(perfluorohexyl)benzylthio]-
2,3,5,6-tetrafluorophenyl}porphyrin (3): Thiol 9 (143 mg, 184 μmol,
6.0 equiv.) was dissolved in ethyl acetate (4 mL) and DMF (2 mL).
Diethylamine (60 μL) and a solution of 5,10,15,20-tetrakis(pen-
tafluorophenyl)porphyrin (30 mg, 30.8 μmol, 1.0 equiv.) in DMF
(3 mL) was added. After stirring for 1 h, aqueous workup, and pu-
rification by CC (silica gel; hexane/acetone, 9:1) product 3 (109 mg)
was obtained as a purple solid in a yield of 89 %. 1H NMR
(400 MHz, CDCl3): δ = 8.69 (s, 8 H, β-H), 7.91 (s, 8 H, Ar-H),
4.49 (s, 8 H, CH2), 2.64 (s, 12 H, CH3), –2.96 (s, 2 H, NH) ppm.
19F NMR (376 MHz, CDCl3): δ = –81.2 (t, J = 10 Hz, 24 F, CF3),
–103.6 (m, 16 F, CF2), –120.2 (m, 16 F, CF2), –121.9 (m, 16 F,
CF2), –123.0 (m, 16 F, CF2), –126.5 (m, 16 F, CF2), –134.0 (m, 8
F, Ar-F), –136.9 (m, 8 F, Ar-F) ppm. MS (MALDI-ToF): m/z (%) =
3990 (100) [M]+. HPLC (FluoroFlash; 1.4 mLmin–1; 24 bar; 100%
THF; 50 °C): tR = 7.07 min (97.2%). UV/Vis (CH2Cl2): λ = 415,
508, 536, 584 nm.
1
solid in a yield of 75%. H NMR (400 MHz, CDCl3): δ = 8.94 (s,
8 H, Ar-H), 4.31–4.23 (m, 4 H, ArNHCH2), 3.82–3.73 (m, 8 H,
CH2), 2.45–2.29 (m, 8 H, CH2), 2.21–2.11 (m, 8 H, CH2), –2.85 (s,
2 H, NH) ppm. 19F NMR (376 MHz, CDCl3): δ = –81.0 (t, J =
10 Hz, 12 F, CF3), –114.2 (m, 8 F, CF2), –121.8 (m, 8 F, CF2),
–122.1 (m, 16 F, CF2), –122.9 (m, 8 F, CF2), –123.5 (m, 8 F, CF2),
–126.3 (m, 8 F, CF2), –140.2 (m, 8 F, Ar-F), –160.9 (m, 8 F, Ar-
F) ppm. MS (MADI-ToF): m/z (%) = 2802 (100) [M]+. HPLC
5,10,15,20-Tetrakis{4-[2,2-bis(3-perfluorohexylpropyl)ethyl-
thio]-2,3,5,6-tetrafluorophenyl}porphyrin (5): Thiol 14 (321 mg,
410 μmol, 10.0 equiv.) was dissolved in ethyl acetate (1.5 mL) and
DMF (6 mL). Diethylamine (150 μL) and a solution of 5,10,15,20-
tetrakis(pentafluorophenyl)porphyrin (40 mg, 41.0 μmol,
1.0 equiv.) in DMF (4 mL) was added. After a reaction time of 4 h,
workup, and purification by CC (silica gel; hexane/acetone, 12:1)
title compound 5 (116 mg) was isolated as a purple solid in a yield
of 70%. 1H NMR (400 MHz, CDCl3): δ = 8.90 (s, 8 H, Ar-H), 3.28
(FluoroFlash; 1.4 mL min–1; 24 bar; 100 THF; 50 °C): tR
1.52 min (97.0%). UV/Vis (CH2Cl2): λ = 420, 511, 545, 586 nm.
=
5,10,15,20-Tetrakis{4-[4-methyl-3,5-bis(perfluorohexyl)benzyl-
amino]-2,3,5,6-tetrafluorophenyl}porphyrin (4): Porphyrin derivative
4 was synthesized by following the procedure for amine-substituted
porphyrin 2. A solution of 5,10,15,20-tetrakis(pentafluorophenyl)-
porphyrin (80 mg, 82.1 μmol, 1.0 equiv.) and 4-methyl-3,5-bis(per-
fluorohexyl)benzylamine (622 mg, 821 μmol, 10.0 equiv.) in NMP
(10 mL) was heated in the microwave apparatus. After aqueous
workup and purification by CC (silica gel; hexane/acetone, 9:1)
product 4 (162 mg) was isolated as a purple solid in a yield of 50%.
3
(d, JHH = 6.0 Hz, 8 H, ArSCH2), 2.27–2.10 (m, 16 H, CH2CF2),
1.94–1.83 (m, 4 H, ArSCH2CH), 1.81–1.62 (m, 32 H, CH2), –2.87
(s, 2 H, NH) ppm. 19F NMR (376 MHz, CDCl3): δ = –81.2 (t, J =
10 Hz, 24 F, CF3), –114.5 (m, 16 F, CF2), –122.2 (m, 16 F, CF2),
1H NMR (400 MHz, CDCl3): δ = 8.84 (s, 8 H, β-H), 7.95 (s, 8 H,
3
Ar-H), 4.93 (d, JHH = 6.6 Hz, 8 H, ArCH2NHAr), 4.77–4.68 (m, –123.2 (m, 16 F, CF2), –123.8 (m, 16 F, CF2), –126.5 (m, 16 F,
4 H, ArCH2NHAr), 2.64 (s, 12 H, CH3), –2.91 (s, 2 H, NH) ppm. CF2), –134.3 (m, 8 F, Ar-F), –137.0 (m, 8 F, Ar-F) ppm. MS
19F NMR (376 MHz, CDCl3): δ = –81.2 (t, J = 10 Hz, 24 F, CF3), (MALDI-ToF): m/z (%) = 4022 (100) [M]+. HPLC (FluoroFlash;
–103.7 (m, 16 F, CF2), –120.3 (m, 16 F, CF2), –121.9 (m, 16 F,
CF2), –122.9 (m, 16 F, CF2), –126.4 (m, 16 F, CF2), –139.9 (m, 8
1.4 mLmin–1; 24 bar; 100% THF; 50 °C): tR = 7.12 min (97.7%).
UV/Vis (CH2Cl2): λ = 415, 508, 536, 584 nm.
4832
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 4823–4833

Fluorous Porphyrins as Model Compounds for Molecule Interferometry
[8] P. J. Krusic, A. A. Marchione, F. Davidson, M. A. Kaiser, C.-
P. C. Kao, R. E. Richardson, M. Botelho, R. L. Waterland,
R. C. Buck, J. Phys. Chem. A 2005, 109, 6232–6241.
[9] S. Gerlich, S. Eibenberger, M. Tomandl, S. Nimmrichter, K.
Hornberger, P. J. Fagan, J. Tüxen, M. Mayor, M. Arndt, Nat.
Commun. 2011, 2, 263.
5,10,15,20-Tetrakis(4-{[3,5-bis({[4-methyl-3,5-bis(perfluorohexyl)-
benzyl]oxy}methyl)phenyl]methanethio}-2,3,5,6-tetrafluorophenyl)-
porphyrin (7): Thiol 19 (150 mg, 90.3 μmol, 8.0 equiv.) was dis-
solved in ethyl acetate (5 mL) and DMF (5 mL). Diethylamine
(100 μL) and a solution of 5,10,15,20-tetrakis(pentafluorophenyl)-
porphyrin (11 mg, 11.3 μmol, 1.0 equiv.) in DMF (4 mL) was
added. After stirring for 3.5 h, workup, and purification by a short
CC (silica gel; hexane/acetone, 12:1) the obtained compound mix-
ture was further purified by recycling gel permeations chromatog-
raphy (flow rate: 2.0 mLmin–1, 34 cycles). Desired compound 7
(26 mg) was obtained as a purple solid in a yield of 31%. 1H NMR
(400 MHz, CDCl3): δ = 8.78 (s, 8 H, β-H), 7.71 (s, 16 H, Ar-H),
7.47 (s, 8 H, Ar-H), 7.39 (s, 4 H, Ar-H), 4.65 (s, 16 H, CH2), 4.59
(s, 16 H, CH2), 4.45 (s, 8 H, ArSCH2), 2.46 (s, 24 H, CH3), –2.95
(s, 2 H, NH) ppm. 19F NMR (376 MHz, CDCl3): δ = –81.1 (t, J =
10 Hz, 48 F, CF3), –103.6 (m, 32 F, CF2), –120.2 (m, 32 F, CF2),
–121.9 (m, 32 F, CF2), –123.0 (m, 32 F, CF2), –126.4 (m, 32 F,
CF2), –133.8 (m, 8 F, Ar-F), –137.5 (m, 8 F, Ar-F) ppm. MS
(MALDI-ToF): m/z (%) = 7550 (100) [M]+. UV/Vis (CH2Cl2): λ =
415, 508, 536, 585 nm.
[10] G. Pozzi, F. Montanari, S. Quici, Chem. Commun. 1997, 69–
70.
[11] O. Paleta, M. Benesˇ, J. Koutníková, V. Král, Tetrahedron Lett.
2002, 43, 6827–6831.
[12] C. R. Becer, R. Hoogenboom, U. S. Schubert, Angew. Chem.
Int. Ed. 2009, 48, 4900–4908.
[13] M. Suzuki, S. Shimizu, J.-Y. Shin, A. Osuka, Tetrahedron Lett.
2003, 44, 4597–4601.
[14] J. Kvícala, M. Benesˇ, O. Paleta, V. Král, J. Fluorine Chem. 2010,
131, 1327–1337.
[15] K. M. Kadish, B. C. Han, M. M. Franzen, C. Araullo-McAd-
ams, J. Am. Chem. Soc. 1990, 112, 8364–8368.
[16] P. Battioni, O. Brigaud, H. Desvaux, D. Mansuy, T. G. Traylor,
Tetrahedron Lett. 1991, 32, 2893–2896.
[17] J. Králová, T. Brˇíza, I. Moserová, B. Dolenský, P. Vasˇek, P.
Poucˇková, Z. Kejík, R. Kaplánek, P. Martásek, M. Dvorˇák, V.
Král, J. Med. Chem. 2008, 51, 5964–5973.
[18] F. da. C. Santos, A. C. Cunha, M. C. B. V. de Souza, A. C.
Tomé, M. G. P. M. S. Neves, V. F. Ferreira, J. A. S. Cavaleiro,
Tetrahedron Lett. 2008, 49, 7268–7270.
Supporting Information (see footnote on the first page of this arti-
cle): HPLC chromatograms of 1–6 and side products 1fivefold and
5threefold, UV/Vis spectra of 1–7, and the recycling GPC chromato-
[19] R. Breslow, Z. Fang, Tetrahedron Lett. 2002, 43, 5197–5200.
[20] T. Brˇíza, R. Kaplánek, M. Havlík, B. Dolenský, Z. Kejík, P.
Martásek, V. Král, Supramol. Chem. 2008, 20, 237.
[21] D. Samaroo, M. Vinodu, X. Chen, C. M. Drain, J. Comb.
Chem. 2007, 9, 998–1011.
gram of 7.
Acknowledgments
[22] A. Varotto, L. J. Todaro, M. Vinodu, J. Koehne, G.-yu Liu,
C. M. Drain, Chem. Commun. 2008, 4921.
[23] R. Kaplánek, T. Bríza, M. Havlík, B. Dolenský, Z. Kejík, P.
Martásek, V. Král, J. Fluorine Chem. 2006, 127, 386–390.
[24] R. P. Volante, Tetrahedron Lett. 1981, 22, 3119–3122.
[25] O. Mitsunobu, M. Yamada, Bull. Chem. Soc. Jpn. 1967, 40,
2380–2382.
[26] H. R. Ing, R. H. F. Manske, J. Chem. Soc. 1926, 129, 2348.
[27] X. Moreau, J.-M. Campagne, J. Org. Chem. 2003, 68, 5346–
5350.
[28] D. Samaroo, C. E. Soll, L. J. Todaro, C. M. Drain, Org. Lett.
2006, 8, 4985–4988.
[29] D. P. Curran, Synlett 2001, 1488–1496.
[30] S. Deachapunya, A. Stefanov, M. Berninger, H. Ulbricht, E.
Reiger, N. L. Doltsinis, M. Arndt, J. Chem. Phys. 2007, 126,
164304.
[31] A. Stefanov, A. Stibor, A. Dominguez-Clarimon, M. Arndt, J.
Chem. Phys. 2004, 121, 6935.
We acknowledge financial support by the Swiss National Science
Foundation and the NCCR “Nanoscale Science”. The groups in
Vienna and Basel were supported by the ESF EuroCore Program
MIME (I146-N16). We acknowledge support through the Austrian
FWF Wittgenstein grant (Z149-N16) and the doctoral program
CoQuS (Grant W1210-N16).
[1] L. Hackermüller, S. Uttenthaler, K. Hornberger, E. Reiger, B.
Brezger, A. Zeilinger, M. Arndt, Phys. Rev. Lett. 2003, 91,
090408.
[2] M. Arndt, O. Nairz, J. Voss-Andreae, C. Keller, G.
van der Zouw, A. Zeilinger, Nature 1999, 401, 680–682.
[3] B. Brezger, L. Hackermüller, S. Uttenthaler, J. Petschinka, M.
Arndt, A. Zeilinger, Phys. Rev. Lett. 2002, 88, 100404.
[4] J. Tüxen, S. Gerlich, S. Eibenberger, M. Arndt, M. Mayor,
Chem. Commun. 2010, 46, 4145.
[5] S. Gerlich, L. Hackermüller, K. Hornberger, A. Stibor, H. Ul-
bricht, M. Gring, F. Goldfarb, T. Savas, M. Müri, M. Mayor,
M. Arndt, Nat. Phys. 2007, 3, 711–715
[6] S. Gerlich, M. Gring, H. Ulbricht, K. Hornberger, J. Tüxen,
M. Mayor, M. Arndt, Angew. Chem. Int. Ed. 2008, 47, 6195–
6198.
[32] S. Deachapunya, P. J. Fagan, A. G. Major, E. Reiger, H. Ritsch,
A. Stefanov, H. Ulbricht, M. Arndt, Eur. Phys. J. D 2007, 46,
307–313.
[33] K. Hornberger, S. Gerlich, H. Ulbricht, L. Hackermüller, S.
Nimmrichter, I. V. Goldt, O. Boltalina, M. Arndt, New J. Phys.
2009, 11, 043032.
[7] N. L. Stock, D. A. Ellis, L. Deleebeeck, D. C. G. Muir, S. A.
Mabury, Environ. Sci. Technol. 2004, 38, 1693–1699.
Received: May 7, 2011
Published Online: July 13, 2011
Eur. J. Org. Chem. 2011, 4823–4833
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4833