How many molecular layers of polar solvent molecules control chemistry? the concept of compensating dipoles

Article abstract of DOI:10.1002/chem.201300770

The extension of the solvent influence of the shell into the volume of a polar medium was examined by means of anti-collinear dipoles on the basis of the E_T(30) solvent polarity scale (i.e., the molar energy of excitation of a pyridinium-N-phen

Full text of DOI:10.1002/chem.201300770

FULL PAPER
DOI: 10.1002/chem.201300770
How Many Molecular Layers of Polar Solvent Molecules Control Chemistry?
The Concept of Compensating Dipoles
Heinz Langhals,* Patricia Braun, Christian Dietl, and Peter Mayer[a]
Dedicated to Professor Wolfgang Beck on the occasion of his 80th birthday
Abstract: The extension of the solvent
influence of the shell into the volume
of a polar medium was examined by
means of anti-collinear dipoles on the
basis of the ET(30) solvent polarity
scale (i.e., the molar energy of excita-
U
dye;
generally:
ET =
consequence, solvent polarity effects
are concentrated to a very thin layer of
a few thousand picometres around the
solute where extensions into the bulk
solvent become unimportant. A paral-
lelism to the thin surface layer of water
to the gas phase is discussed.
)
where no
Keywords: dipoles
solvatochromism · solvent shells
·
polarity
·
tion of
a
pyridinium-N-phenolate-
Introduction
vents because its strong negative solvatochromism allows
the detection of even small medium effects with high sensi-
tivity (see Figure 1). The solvent-induced spectral band
Both the majority of technical syntheses and biological proc-
esses proceed in liquids where solvent effects play a pre-
dominant role. Polar interactions between dissolved material
and the solvent are of special importance where the knowl-
edge of such interactions is essentially based on the funda-
mental works of Debye, Onsager, Clausius-Mossotti and
Hꢀckel about the interaction of spherical, charged particles
or dipoles in solvents as dielectric media. However, such
Coulomb interactions are comparably long reaching and
hardly represent the majority of chemically important cases.
Weaker fluctuating dipole–dipole interactions dominate
mostly where a faster damping with increasing distance can
be expected. There are many concepts for the description of
such solvent effects,[1] however, a final solution for this prob-
lem is still lacking; this may be complicated by varying influ-
ences of both the bulk solvent and the contact layer be-
tween the solvent and the solute. One may ask how many
molecular layers of solvent molecules are important for the
polar control of chemical reactions.
Figure 1. Left) Molecular structure of the betaine dye 1 as the basis of
the ET(30) solvent polarity scale, the direction of the ground-state dipole
moment and its molecular dimensions. Right) Electronic highest occupied
molecular orbital (HOMO, bottom) and lowest unoccupied molecular or-
bital (LUMO, top) of 1, as obtained by DFT calculations (B3-LYP).[4]
Results and Discussion
We applied the pyridinium-N-phenolatebetaine dye 1 (be-
taine No. 30) of Dimroth and Reichardt[2,3] as a molecular
probe for the interaction of dipolar substrates with polar sol-
shifts of 1, which are observed in solvents of different polari-
ty, are caused by the differential solvation of the highly di-
polar zwitterionic electronic ground state of 1 (S0) and its
much less dipolar first excited state (S1); in polar solvents,
the ground state is much more stabilised by solvation than
the excited state (see Figure 2). As a consequence, the
colour of a solution of 1 shifts from yellow (absorbing at
short wavelengths) in highly polar media through the visible
until the near-infrared (NIR) region for media with low sol-
[a] Prof. Dr. H. Langhals, Dr. P. Braun, C. Dietl, Dr. P. Mayer
Department of Chemistry, LMU University of Munich
Butenandtstrasse 13, 81377 Munich (Germany)
Fax : (+49)89-2180-77640
E-mail: Langhals@lrz.uni-muenchen.de
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201300770.
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the recently studied question[6] about the extension of the in-
terfacial layer between water and the gas phase.
We started the synthesis of a dyad with two anti-collinear-
ly arranged chromophores of 1 with 4-bromobenzaldehyde
(2) and allowed a condensation with acetophenone to form
the pyrylium salt[7] 3 as a key intermediate for the new
dyads 8 and 10 (see Scheme 1). 2,6-Diphenylphenol (4) was
nitrated[8] to give intermediate 5, which was reduced to form
4-amino-2,6-diphenylphenol (6). The latter was allowed to
react in a convergent synthesis with the pyrylium salt 3 to
give product 7, which was coupled in a Heck reaction to
form the dyad 8 with anti-collinear dipoles; the solvent po-
larity scale derived from 8 will be consequently named
Figure 2. Solvent influences causing the solvatochromism of 1; the large
dipole in the ground state (S0) of 1 is strongly solvated in polar media
and appreciably lowered in energy, whereas the small dipole in the elec-
tronically excited state (S1) is only slightly solvated (vertical transitions
hn and hn’, respectively).
ETACHTUNGTRNE(NUNG 30dyad).
The application of 1 is limited to non-acidic solvents be-
vent polarity such as 1,4-dioxane. The molar energy of exci-
tation of 1 is applied as the solvent polarity scale ET(30)[3]
(generally: ET =28591 nmkcalmolꢀ1/lmax).
cause the strongly basic phenolate anion is easily protonat-
ed. Wolfbeis et al. have synthesised[9] the betaine derivative
11 (see Scheme 2), which is less basic because of the elec-
tron-withdrawing effect of the two chlorine atoms and they
named it pyridinium-N-phenolate 33 as a continuation of
the initially published series of betaine dyes; as a conse-
quence, the solvent polarity scale on the basis of 11 was
named ET(33). We prepared the dyad 10 of the chromo-
phore of 11 analogously to 8 by the condensation of 4-
amino-2,6-dichlorophenol with 3 to give 9, which was cou-
pled to form 10 as the analogue of 8. The corresponding sol-
We constructed anti-collinear dyads where the dipole of 1
compensates in order to test the extension of the solvent
shell. Very thin solvent shells would be able to solvate the
individual dipoles with individual solvatochromism, whereas
compensation would be expected to become more and more
important with the extension of the solvent shell and finally
extinguish solvatochromism for very large shells; compare
also reference [5]. There is some relation of this question to
Scheme 1. Synthesis of anti-collinear dyads 8 and 10 of the betaine dyes used for the extension of the ET(30) and the ET(33) solvent polarity scales.
i) Acetophenone. ii) HNO3. iii) Na2S2O4. iv) Pd(OAc)2, Ac=acyl.
AHCTUNGTRENNUNG
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The Concept of Compensating Dipoles
FULL PAPER
A spacer with a diamantane structure was introduced for
the arrangement of two laterally displaced chromophores of
1 still keeping their long axes parallel. Thus, the diiodo dia-
mantane[11] 19 was allowed to react with CuCN to form the
dinitile 20, where the dialdehyde 21 was prepared by reduc-
tion with DIBAL-H. A further condensation with acetophe-
none formed the bispyrylium perchlorate 22 (Caution! Com-
pound 22 may be explosive!) applied without further purifi-
cation for the subsequent condensation with diphenylamino-
phenol to form 23 (Scheme 4).
Scheme 2. The pyridinium-N-phenolate betaine dyes 11 and 24 as the
basis of the solvent polarity scales ET(33)[9] and E
tBu=tert-butyl.
TACHTUNGRTEN(NUNG 30tBu), respectively.
The electronic transition of the longest-wavelength light
absorption of 1 (more than l=450 nm) proceeds essentially
between the HOMO and the LUMO for which we report
the quantum-chemically calculated orbitals (DFT method
B3-LYP)[4] in Figure 1. For the corresponding HOMO/
LUMO calculations of 1 (ZINDO, DFT and COSMO meth-
ods) see also reference [18]. The p-electron density of the
HOMO is concentrated at the phenolate ion, whereas in the
LUMO the electron density is more located around the ni-
trogen atom of the pyridinium ring. As a consequence, the
electronic excitation causes an appreciable shift of the
charge along the long molecular axis according to the exper-
imentally observed reduction of the dipole moment. A
direct experimental evidence for the light-induced intramo-
lecular charge-transfer was found by Schmuttenmaer
et al.[19] by means of terahertz spectroscopy. We calculated a
dipole moment of 12 D for the ground state; this value is in
the same order as the experimental result for similar com-
pounds.[2,20]
vent polarity scales were designated as E
TA(30dyad), respectively.
We further wanted to diminish any p interactions between
the components of dyads with compensating dipoles and in-
troduced a bicyclo[2.2.2]octane unit as a stiff, purely aliphat-
TACHTUNGTRENUN(NG 33dyad) and
E CHTUNGTRENNUNG
ACHTUNGTRENNUNG
ic spacer. The synthesis started with the diphenyl[10] deriva-
tive 12, where iodation with hypervalent iodine com-
pounds[11] gave the iodide 13 and a reaction[12] with CuCN in
NMP gave the dinitrile 14 (Scheme 3).[13] A reduction with
DIBAL-H[12] allowed the preparation of the dialdehyde
15[14] and a base-induced condensation with acetophenone
analogously to reference [15] yielded the tetraketone 16.
The latter was cyclized with acetic anhydride analogously to
reference [16] and crystallised as the naphthalene sulpho-
nate 17. A final condensation with diphenylaminophenol
gave the bicycloACHTUNGTRENNUNG[2.2.2]octane derivative 18 analogously to
reference [8]. Finally, 4-(4-tert-butylphenyl)-2,6-diphenyl-
pyrylium tetrafluoroborat was prepared in analogy to refer-
ence [17] and condensed with diphenylaminophenol in anal-
ogy to reference [8] to obtain compound 24 for comparison,
Compound 1 exhibits only very weakly fluorescence,[21]
preferment at low temperature; for fast photo physical proc-
esses see reference [22]. The spectrum of 1 in the typical sol-
vent acetone is recorded in Figure 3 (solid line). An energy-
linear Gaussian analysis[23] with the parameters Ei, li and si
of the spectrum according to Equation (1) was successful
and the positions and intensities of the Gaussian bands are
ꢀ
where the central C C-bonds in 18 are formally cut and re-
placed by hydrogen atoms. As a consequence, compound 24
represents one functional chromophore of the dyad 18.
Scheme 3. Synthesis of anti-collinear dyad 18 of the betaine dyes used for the extension of the ET(30) and the ET(33) solvent polarity scales. i) (Bis(tri-
fluoroacetoxy)iodo)benzene, I2. ii) CuCN, N-methyl-2-pyrrolidine (NMP). iii) Diisobutylaluminium hydride (DIBAL-H). iv) Acetophenone, base.
v) Acetic anhydride, naphthalsulfonic acid. vi) 4-Amino-2,6-diphenylphenol.
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H. Langhals et al.
Compound 8 formally repre-
sents a donor–acceptor–accept-
or–donor system; for more
structures of polar components
forming centrosymmetric or
quadrupolar dyes and their sol-
vent influences see refer-
ence [26].
We tested the extension of
the solvent shells experimen-
tally by means of the anti-col-
linear arrangement of the indi-
vidual two chromophores of 1
in dyad 8 where the dipole mo-
ments compensate in the
whole molecule (see Figure 4
bottom). Indeed, an insignifi-
cantly small dipole moment
was calculated for 8 by the
DFT method[4] (m<0.001 D).
Dyad 8 is still strongly nega-
tively solvatochromic (see
Figure 5 for the solvent polari-
ty-induced shift of the band at
longest wavelengths). The ab-
sorption of 8 resembles 1 (see
Scheme 4. Synthesis of anti-collinear dyad 23 of the betaine dyes used for the extension of the ET(30) and the
ET(33) solvent polarity scales. i) CuCN, DMF. ii) Diisobutylaluminium hydride (DIBAL-H). iii) Acetophenone,
HClO4. iv) 1. 4-Amino-2,6-diphenylphenol, 2. NaOH.
Figure 3. UV/Vis spectrum of 1 [ET(30) scale] in acetone (thick, solid
line) and Gaussian analysis of the spectrum. Dotted line (mostly covered
by the solid line): simulated spectrum on the basis of the Gaussian analy-
sis. Bars: Positions and intensities of the Gaussian bands. Dashed line:
UV/Vis spectrum of the dyad 18 [ETACTHNUTRGENNU(G 30bic)]. Bic=bicycloACHTUTGNREN[NUGN 2.2.2]octane.
shown in Figure 3 as bars; compare reference [24]. The si-
mulated spectrum on the basis of this analysis is very close
to the experimental spectrum (dotted line in Figure 3 nearly
completely covered by the solid line of the experimental
spectrum). Two Gaussian functions were found for the most
bathochromic absorption with the absorption maximum in
between; the whole spectrum in the visible can be split into
n=6 Gaussian functions; compare reference [25] for the
Figure 4. Bottom) Molecular structure of the ground state of the dyad 8,
showing the anti-collinear orientation of the internal ground-state dipole
moments, and its molecular dimensions. Top) Electronic HOMO
(bottom) and LUMO (top) of 8 obtained by DFT calculations (B3-
LYP).[4]
simulation of the bathochromic absorption maximum.
2
1
l
1
li
2s2i
ꢀ
n
ð
Þ
X
EðlÞ
¼
Ei ꢁ eꢀ
ð1Þ
i¼0
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The Concept of Compensating Dipoles
FULL PAPER
compare reference [21]. Otherwise, the slope should be less
than unity because the dipoles compensate for far-reaching
interactions. The sensitivity of the system to dipole–dipole
interactions is indicated by the non-zero intercept caused by
static arrangement of the two intramolecular dipoles in 8.
We could support this results with an analogous investiga-
tion by means of the dyad 10, that is, ETACTHNUTRGNE(NUG 33dyad), and the
betaine dye 11 as the basis of the ET(33) solvent polarity
scale, and obtained completely analogous results with a
slope of 1.08 for the linear ETACHTNUTRGNENUG(33dyad)/ET(33) correlation,
even with respect to the reported special solvent interac-
tions[29] of chlorine atoms. This must be unimportant in 10
for the extension of the very small solvent shell (see
Figure 7). The verification of the results obtained with 8 by
means of 10 can be taken as an indication for a more gener-
al effect.
Figure 5. UV/Vis spectra of 8 in selected solvents with its long-wave-
length absorption band around l=500–800 nm, measured in thirteen sol-
vents at room temperature. From right to left: chlorobenzene (solid), di-
glyme (dashed), dichloromethane (dotted), butanone (solid), acetone
(dashed), DMF (dotted), DMSO (solid), acetonitrile (dashed), 1-butanol
(dotted), 1-propanol (solid), ethanol (dashed), ethanol/water 80:20
(dotted), methanol (solid).
Figure 4 for comparison) and a Gaussian analysis results in
similar parameters. The molar energy of the excitation of 8,
that is, ETACHTUNGTRENNUNG(30dyad), was compared with that of the non-com-
pensating monochromophoric 1, that is, ET(30), for twenty
pure solvents of different solvent polarity (see Figure 6). A
Figure 7. Solvatochromism of 10 [ETACTHNUTRGENUGN(33dyad)] for thirteen pure solvents
compared with the solvatochromism of 11 [ET(33)] and linear correlation
according to the least squares. Slope: 1.08. Intercept: ꢀ6.42. Correlation
number r: 0.996 for n=13. Standard deviation in ETACHTNUTRGNE(NUG 33dyad): 1.5.
Finally, we wanted to definitely exclude any influence by
the residual conjugation between the chromophores in the
dyads. To this end, we introduced the purely aliphatic, stiff
bicycloACHTNUTRGNE[UNG 2.2.2]octane spacer in the dyad 18 as a barrier. A
slightly increased size to 3100 pm was calculated for 18 with
Figure 6. Solvatochromism of 8 [ETACTHNUTRGENUGN(30dyad)] for twenty pure solvents
compared with the solvatochromism of 1 [ET(30)] and their mutual linear
correlation calculated by the least square method. Slope: 1.02. Intercept:
ꢀ2.43. Correlation number r: 0.993, for n=20. Standard deviation in
E CHTUNGTRENNUNG(30dyad): 0.7. Ionic liquid: The ionic liquid used was 1-butyl-3-methyl-
TA
still 1270 pm for each pyridiniumphenolate betaine (see
ACHTUNGTRENNUNGimidazolium tetrafluoroborate.
Figure 8). E
scale analogously to dyad 1. A linear correlation between
TA(30bic) and ETA(30tbu) (i.e., 24) was again found for pure
TACHTUNGTRENUN(NG 30bic) was defined for 18 as a solvent polarity
linear relationship war found between the E
N
E
C
CHTUNGTRENNUNG
and the ET(30) scale, based on 1, with an unusually good
correlation number of r=0.993 (n=20), including solvents
such as benzyl alcohol with complex solvent interactions, an
ionic liquid, and highly polar alcohols, as compared with
other linear-free energy relationships between empirical sol-
vent polarity scales.[1] The exclusion of hydrogen-bond-form-
ing solvents would not alter the result.
The slope of this correlation with 1.01, close to unity, is
even more surprising than the good linear correlation be-
cause it indicates the independent operation of both chro-
mophores in dyad 8 and excludes significant compensating
effects concerning the solvatochromism; as a consequence,
the solvent shell around the dipole of 1 must be extremely
thin and concentrates essentially to one molecular layer;
solvents according to Figure 9, analogously to Figure 6. The
slope is 1.00 with r=0.998 (n=24) and excludes compensat-
ing effects even for completely decoupled chromophores in
dyads.
Extending the concept of compensating dipoles, we later-
ally displaced two chromophores of 1 keeping the long axes
still parallel by means of the introduction of a diamantane
(diam) spacer to obtain 23 (solvent polarity scale
ETACHTNUTRGNEUNG(30diam)); this special arrangement can be seen in the X-
ray crystal structure analysis of 20 in Figure 10. The linear
correlation between the solvent polarity scales derived from
23 and 24 is shown in Figure 11. A slope close to unity was
again obtained for the dipoles arranged slightly out of com-
plete compensation; as a consequence solvation is expected
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H. Langhals et al.
Figure 10. Molecular structure of crystalline 20 as determined by X-ray
analysis. Ellipsoids are drawn at the 50% probability level. The lateral
displacement of the peripheral substituents still keeping their long axes
parallel can be seen.[30]
Figure 11. Solvatochromism of 23 [E
compared with the solvatochromism of 24 [E
tion according to the least squares. Slope: 1.03. Intercept: ꢀ1.34. Correla-
tion number r: 0.999 for n=12. Standard deviation in ETA(30diam): 0.2.
(30diam)] for twelve pure solvents
CTHUNGTRENNUNG
CTHUNGTRENNUNG
Figure 8. Bottom) Dyad 18, the anti-collinear orientation of the dipole
moments and molecular dimensions. Top) Calculated electronic HOMO
(bottom) and LUMO (top) of 18 as obtained by DFT calculations (B3-
LYP).[4]
tween the heteroatoms in 1 is 560 pm. These results are fur-
ther supported by former measurements of a nested (short-
ened by one 1,4-phenylene unit) anti-collinear bisbetaine[28]
described by Dimroth and Reichardt, however, this chromo-
phoric system was not a real dyad of 1 such as 8, 18 and 23,
but nevertheless can be taken as a further, independent indi-
cator. The interaction of dipoles can be simulated with mag-
netic dipoles (see Figure 12).
The surprisingly thin solvation shell of 8 of roughly less
than 500 pm finds its counterpart in the surface layer of
liquid water to the gas phase, which amounts only to about
300 pm and where the unperturbated bulk structure of
water exists already for slightly larger distances. One may
find a parallelism between both effects because a dissolved
molecule in a liquid forms a local disruption of the solvent
structure and generates a novel internal surface around the
dissolved molecule; this analogously resembles the forma-
tion of a surface to the gas phase as a disruption of the bulk
solvent structure.
Figure 9. Solvatochromism of 18 [E
pared with the solvatochromism of 24 [E
according to the least squares. Slope: 1.00. Intercept: ꢀ0.27. Correlation
number r: 0.998 for n=24. Standard deviation in ETA(30bic): 0.3.
(30bic)] for 24 pure solvents com-
CTHUNGTRENNUNG
CTHUNGTRENNUNG
On the other hand, the experimental evidence for a very
thin solvation shell may help in understanding some discrep-
ancies in solvent influences for high polarity. Generally,
functions of the relative permittivity of the solvent (dielec-
tric constant) such as the equation of Onsager or the func-
to proceed very close to the dipoles and remains unaffected
by slight intramolecular displacements.
The experimentally shown independent operation of the
two betaine chromophores in the dyads 8, 10, 18 and 23, in-
dicates that dipolar compensating effects are unimportant.
As a consequence, the significant solvation shell around the
two molecular dipoles must be very small and can be rough-
ly estimated to extend no more than half the dimension of
1, and this is in the order below 500 pm. The distance be-
tion of Kirkwood, (erꢀ1)/
ACHTUNGTNER(NUGN 2er+1), are popular measures for
the solvent polarity and are successfully applied for solvents
with low polarity. However, the very high er of N-methyl-
A
ACHTUNGTRENaNUNG mide of 191 (at 358C), for example, would imply a
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The Concept of Compensating Dipoles
FULL PAPER
by means of the strong solvatochromism of pyridinium-N-
phenolate betaine dyes. The molecular dimensions of the in-
vestigated anti-collinear dipoles indicate a small solvent
shell of only a few hundred picometres where the polar sol-
vent properties seem to concentrate to a molecular layer.
This resembles the very thin layer of about 300 pm found
for the interface between water and the gas phase. A possi-
ble reason is the strong thermal movement of the solvent
molecules causing a scrambling of the interaction and a very
rapid damping with an increasing distance.
Experimental Section
General methods: Column chromatography was performed by using SiO2
(0.040–0.063 mm, 230–400 mesh ASTM) from Merck. IR spectra: Perkin
Elmer 1420 Ratio Recording Infrared Spectrometer, FT 1000 and Perkin
Elmer BXII FT-IR with ATR-unit; UV/Vis spectra: Varian Cary 5000
and Bruins Omega 20; fluorescence spectra: Varian Cary Eclispe; NMR
spectroscopy: Varian Vnmrs 600 (600 MHz); mass spectroscopy: Finnigan
MAT 95.
Compound 8: 4-(4-Bromophenyl)-2,6-diphenyl-N-(3,5-diphenylphenyl-4-
phenolate)pyridinium betaine (7) (500 mg, 793 mmol), tetrabutylammoni-
um bromide (70.4 mg, 218 mmol) and PdACHTUNRGTNEUNG(OAc)2 (2.0 mg, 5.5 mmol) in an-
hydrous toluene (20 mL) under argon atmosphere were treated with trie-
thylamine (1 mL), and heated at 1208C for 20 h. The reaction mixture
was quenched by the addition of 2m aqueous HCl (100 mL), extracted
with CHCl3 (3ꢂ100 mL), washed with 2m aqueous NaOH (100 mL) and
distilled water (100 mL), dried with Na2SO4 and purified by column sepa-
ration (Al2O3, dichloromethane/ethanol 40:1). Yield: 89.0 mg (80.8 mmol,
20%) of a light green solid. M.p.> 2508C; Rf (Al2O3, dichloromethane/
ethanol 20:1)=0.71; 1H NMR (600 MHz, CDCl3, 258C, trimethylsilane
Figure 12. Dipole interactions simulated with magnetic dipoles; corre-
sponding to a molecular size of the dipole of 1300 pm. a) Isolated dipole.
Streamlines of the field are visualized by means of iron filings. b) Two
compensating dipoles with independent action. Distance: 700 pm. c) In-
teraction of the left dipole with a third, close one with a size of 700 pm
and a distance of 700 pm from the connecting line. The right dipole re-
mains essentially unaffected. d) Interaction with a third dipole with a size
of 1300 pm at a distance of 700 pm from the connecting line and a lateral
shift of 700 pm. The third dipole interacts with both dipoles. e) Interac-
tion of compensating dipoles with a third distant dipole with a size of
1300 pm and a distance of 1300 pm from the connecting line. All dipoles
are interacting.
(TMS)): d=5.58 (s, 2H; OH), 7.10 (d, 3J
A
3
7.32–7.41 (m, 28H; Harom.), 7.74 (d, J
U
3J(H,H)=7.9 Hz, 4H; Harom.), 8.12 (d, 3J
ACTHNUGTRENNUGN ACHTUNGTRENNNUG
8.24 ppm (s, 4H; Hpyridinium); 13C NMR (150 MHz, CDCl3, 258C, TMS):
d=125.9, 128.4, 128.5, 128.9, 129.0, 129.1, 129.3, 129.6, 130.1, 130.2, 131.8,
133.4, 133.8, 135.1, 135.9, 136.7, 143.0, 149.9, 155.8, 157.0 ppm; IR (ATR):
n˜ =3050.0 (w), 1619.4 (m), 1595.6 (m), 1575.6 (w), 1562.3 (w), 1543.1 (w),
1493.5 (m), 1464.9 (m), 1420.8 (m), 1358.3 (w), 1241.1 (m), 1123.5 (w),
1063.2 (w), 1048.2 (w), 1029.2 (w), 1001.6 (w), 889.1 (w), 823.6 (w), 759.5
(m), 730.6 (m), 698.0 (s), 673.7 (m), 673.7 cmꢀ1 (w); UV/Vis (CH2Cl2/1,5-
whereas both chemical experience and, for example, the
ET(30) solvent polarity scale [ET(30)=52.0] indicate a lower
solvent polarity than water [ET(30)=63.1] where the solvent
refractive index and the ability of donating hydrogen bonds
may be of further influence.[29] The relative permittivity er of
a solvent concerns the solvent properties in the unaffected
volume of a solvent, whereas both the chemical solvent po-
larity and the empirical solvent polarity scale reflect more
inner surface effects of solvents. Polar properties of solvents
may be of similar influence on both the effects in the bulk
and the effects at surfaces and this makes the application of
er useful, however, a strict parallelism is not given and there
are exceptions for some cases such as for N-methylacet-
diazabicycloACHTNUTRGNE[UNG 5.4.0]undec-5-ene (DBU)): lmax (Erel)=358.6 (1.00),
735.2 nm (0.22); MS (FAB+): m/z (%): 1150.6 (0.15), 1137.4 (0.08),
1117.7 (0.18) [M+ +OH], 1102.6 (0.85) [M+ +H], 873.5 (0.15), 857.6
(0.85), 779.5 (0.07), 652.5 (0.09), 627.5 (0.11), 576.0 (0.14), 559.4 (0.10),
551.4 (0.62), 500.4 (0.09); HRMS: m/z calcd for C82H58N2O2: 1102.4487;
found: 1102.4489, D=ꢀ0.0002.
Compound 10: 4-(4-Bromophenyl)-1-(3,5-dichloro-4-phenolate)-2,6-di-
phenylpyridinium betaine (9) (500 mg, 913 mmol), tetrabutylammonium
bromide (81.0 mg, 251 mmol) and PdACHTNUTRGNENG(U OAc)2 (25.0 mg, 110 mmol) in anhy-
drous toluene (20 mL) under argon atmosphere were treated with trie-
thylamine (1 mL), and stirred at 1208C for 16 h. The reaction mixture
was quenched by the addition of 2m aqueous HCl (100 mL), extracted
with CHCl3 (3ꢂ100 mL), washed with 2m aqueous NaOH (100 mL) and
distilled water (100 mL), dried with magnesium sulphate, purified by
column separation (silica gel, CHCl3/EtOH 2:1), dissolved in a small
amount of ethanol, precipitated with 2m aqueous NaOH and washed
with distilled water (50 mL). Yield: 166 mg (36%) of a reddish violet
solid. M.p.> 2508C; Rf (silica gel, CHCl3/EtOH 2:1)=0.66; 1H NMR
(400 MHz, CD3OD, 258C, TMS): d=7.05 (s, 4H; Hphenol), 7.47–7.75 (m,
ACHTUNGTRENNUNGamide. The strong thermal motions in liquids at room tem-
perature may be responsible for whipping-out arrangements
of larger distance in liquids so that the direct contact of the
solute with the solvent remains dominating.
20H; Hphenyl), 8.10 (d, 3J(H,H)=8.7 Hz, 4H; Harom.), 8.38 (d, 3J
ACTHNUTRGENNUG ACHTUNGTRENNUNG(H,H)=
Conclusion
8.7 Hz, 4H; Harom.), 8.57 ppm (s, 4H; Hpyridinium); 13C NMR (100 MHz,
CD3OD, 258C, TMS): d=123.1, 125.3, 127.6, 128.2, 128.3, 129.3, 129.6,
130.1, 133.7, 142.9, 155.2, 157.7, 160.6 ppm; IR (ATR): n˜ =3186.5 (w),
3051.4 (w), 2362.1 (w), 2338.8 (w), 1616.4 (m), 1590.4 (m), 1573.6 (m),
We resume that no compensating effects were found for the
solvation of two anti-collinear molecular dipoles, analysed
Chem. Eur. J. 2013, 00, 0 – 0
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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H. Langhals et al.
1558.7 (m), 1531.0 (m), 1504.7 (s), 1489.7 (s), 1449.2 (w), 1443.8 (w),
1391.3 (w), 1350.9 (w), 1259.5 (m), 1240.5 (m), 1183.4 (w), 1158.1 (w),
1122.2 (w), 1062.2 (w), 1039.5 (m), 1000.0 (w), 983.6 (w), 925.6 (w), 894.7
(w), 886.9 (w), 872.1 (w), 834.5 (w), 819.9 (m), 792.0 (w), 781.8 (m), 771.1
(s), 744.0 (w), 697.7 (s), 667.9 cmꢀ1 (w); UV/Vis (CH2Cl2): lmax (Erel)=
362.8 (1.00), 555.2 nm (0.10); MS (ESI+): m/z (%): 935.2 (0.1) [M++H],
479.6 (0.3), 468.1 (1.0) [M2++H]; elemental analysis calcd (%) for
C58H36Cl4N2O2·4H2O (1006.8): C 69.19, H 4.41, N 2.78; found: C 69.58, H
4.30, N 2.78.
1,4-Bis-(4-iodophenyl)bicyclo
ACHTUNGTRENNUNG[2.2.2]octane (1.32 g, 4.98 mmol) in CHCl3 (27 mL) was added to (bis(tri-
ACHTUNGTRENUN[NG 2.2.2]octane (13): 1,4-Bisphenylbicyclo-
8H; CH2C=O), 4.05 (quin., 3J
ACHTUNGTRENNUNG
3
A
G
fluoroacetoxy)iodo)benzene (4.45 g, 9.42 mmol) and iodine (2.02 g,
4.76 mmol) under an argon atmosphere, stirred at room temperature for
160 min, poured into distilled water (40 mL) and treated with Na2SO3
until becoming colourless. The organic phase was separated, dried with
Na2SO4, evaporated and the residue was purified by crystallisation from
chlorobenzene. Yield: 1.12 g (44%) of a colourless solid. M.p.>2508C;
1H NMR (400 MHz, CD2Cl2, 258C, TMS): d=1.92 (s, 12H;
(t, 3J(H,H)=7.6 Hz, 4H; CHarom.), 7.94 ppm (d, 3J
ACTHNUGTRENNUGN ACHTUNGTRENNNUG
CHarom.); 13C NMR (150 MHz, CDCl3, 258C, TMS): d=32.7, 34.7, 36.6,
44.9, 125.7, 127.1, 128.1, 128.5, 133.0, 136.9, 140.9, 148.1, 198.7 ppm; MS
(EI+): m/z: 762.37.
CH2bicyclo[2.2.2]octane), 7.13 (d, 3J
3J(H,H)=8.4 Hz, 4H; CHphenyl); 13C NMR (100 MHz, CD2Cl2, 258C,
ACHTGNURTENUN(NG H,H)=8.4 Hz, 4H; CHphenyl), 7.63 ppm (d,
ACHTUNGTRENNUNG
TMS): d=32.4, 34.8, 90.6, 127.8, 137.0, 149.6 ppm; IR (ATR): n˜ =2935.1
(w), 2857.6 (w), 2360.7 (s), 2341.1 (s), 1558.9 (w), 1540.3 (w), 1485.2 (w),
1456.4 (w), 1389.5 (w), 1056.3 (w), 1004.1 (w), 989.3 (m), 810.0 (m), 757.8
(w), 709.8 (w), 689.6 (w), 668.0 cmꢀ1 (m); HRMS; m/z calcd for C20H20I2:
513.9654; found 513.9656, D=ꢀ0.0002; elemental analysis calcd (%) for
C20H20I2 (513.9): C 46.72, H 3.92; found: C 47.42, H 4.09.
Bispyrylium salt 17: Triphenylmethanol (308 mg, 1.18 mmol), naphthale-
nesulphonic acid monohydrate (264 mg, 1.18 mmol) and acetanhydride
(3.7 mL) were stirred for 3 h at room temperature. The obtained solution
was added to compound 16 (188 mg, 246 mmol) in acetanhydride (2 mL),
stirred at 1008C for 1 h and allowed to cool down for crystallisation. The
solid was collected by vacuum filtration, thoroughly washed with cold
acetic anhydride and ethanol and dried in medium vacuum. Yield:
245 mg (87%) of a yellow solid. M.p.>2508C; 1H NMR (400 MHz,
[D6]DMSO, 258C, TMS): d=2.04 (s, 12H; CH2), 7.47–7.50 (m, 4H;
1,4-Bis-(4-cyanophenyl)bicyclo
[2.2.2]octane
(14):
CuCN
(798 mg,
8.91 mmol) and 1,4-bis(4-iodophenyl)-bicycloAHCTUNGERTG[NNUN 2.2.2]octane (13) (1.10 g,
2.14 mmol) were dissolved in N-methylpyrrolidone (NMP) (14.5 mL) and
heated at 2008C (bath) for 7 h. Toluene (300 mL) was added and the
mixture was washed with 7.5% aqueous ethylenediamine solution
(250 mL) and distilled water (20 mL), dried with Na2SO4 and evaporated.
The residue was purified by column separation (silica gel, CHCl3/isohex-
ane 4:1). Yield: 210 mg (31%) of a colourless solid. Rf (silica gel, CHCl3/
isohexane 4:1)=0.56; 1H NMR (200 MHz, CDCl3, 258C, TMS): d=1.98
(s, 12H; CH2), 7.46 (td, 3J
ACHUTNERGUNNG AHCUTNGTNERN(GUN H,H)=1.8 Hz, 4H; CHphenyl),
(H,H)=8.9, 4J
ACTHNGUTERNNUG
CHnaphthyl), 7.67–7.70 (m, 2H; CHnaphthyl), 7.75–7.79 (m, 12H; CHphenyl
,
7.61 ppm (td, 3J(H,H)=8.9, 4J(H,H)=1.8 Hz, 4H; CHphenyl); MS (EI+):
G
CHphenyl bicyclooctane), 7.81–7.92 (m, 10H; CHnaphthyl, CHphenyl bicyclooctane), 8.11
ꢀ
ꢀ
m/z (%): 312.2 (100) [M+], 283.2 (8), 155.1 (65), 116.1 (24); HRMS: m/z
calcd for C22H20N2: 312.1626; found: 312.1629, D=0.0003.
(s, 2H; CHnaphthyl), 8.55–8.57 (m, 12H; CHphenyl), 9.11 ppm (s, 4H;
CHpyrylium); IR (ATR): n˜ =3424 (w), 3053 (w), 2942 (w), 2861 (w), 1715
(w), 1623 (m), 1593 (s), 1577 (m), 1511 (m), 1491 (s), 1466 (m), 1437 (m),
1404 (w), 1362 (w), 1344 (w), 1256 (m), 1222 (m), 1194 (s), 1134 (m),
1088 (m), 1029 (s), 995 (m), 953 (w), 901 (w), 862 (w), 840 (w), 818 (m),
778 (m), 749 (w), 718 (w), 672 cmꢀ1 (s); HRMS: m/z calcd for C54H44Oþ2 :
724.3341; found: 724.3307, D=ꢀ0.0034.
1,4-Bis(4-formylphenyl)bicyclo
[2.2.2]octane
(15):
1,4-Bis(4-cyano-
A
ACHTUNGTRENNUNG
CH2Cl2 (3.6 mL), cooled to 08C, treated slowly dropwise with DIBAL-H
(1m in n-hexane, 1.62 mL, 1.62 mmol) and the reaction was allowed to
proceed at room temperature for 3 h. The reaction mixture was poured
into 6m aqueous HCl solution (10 mL) and some ice and stirred for 1 h.
The organic phase was separated and the aqueous phase was extracted
with CH2Cl2 (3ꢂ50 mL). The combined organic phases were washed with
saturated aqueous NaHCO3 solution (100 mL) and distilled water
(100 mL), dried with Na2SO4, evaporated and purified by column separa-
tion (silica gel, CHCl3/isohexane 4:1). Yield: 228 mg (716 mmol, ꢂ100%)
1
of a colourless solid. Rf (silica gel, CHCl3/isohexane 4:1)=0.29; H NMR
(200 MHz, CDCl3, 258C, TMS): d=2.03 (s, 12H; CH2), 7.54 (d, 3J-
ACHTUNGTRENNUNG ACHTUNTGREN(NUGN H,H)=8.4 Hz, 4H; CHphenyl),
(H,H)=8.4 Hz, 4H; CHphenyl), 7.84 (d, 3J
9.99 ppm (s, 2H; CHO); MS (EI+): m/z (%): 318.2 (100) [M+], 289.2 (5),
160.2 (45), 130.1 (25), 91.1 (12); HRMS: m/z calcd for C22H22O2:
318.1620; found: 318.1609, D=ꢀ0.0011.
Compound 18 [ETACHTUNTRGNEUNG(30bic)]: Compound 17 (240 mg, 211 mmol) and 4-
amino-2,6-diphenylphenol (480 mg, 420 mmol) were dispersed in anhy-
drous ethanol (4.8 mL), heated to reflux, treated with anhydrous sodium
acetate (240 mg, 1.34 mmol), heated to reflux for 3 h, allowed to cool
down, poured into 2m aqueous NaOH solution (100 mL) and extracted
with CH2Cl2 (3ꢂ150 mL). The combined organic phases were washed
with distilled water until becoming neutral, dried with MgSO4, evaporat-
ed in vacuo and purified by column separation (Al2O3 neutral, toluene/
methanol 10:1). Yield: 119 mg (47%) of a green solid. M.p.>2508C; Rf
(Al2O3, neutral, toluene/methanol 10:1)=0.10; 1H NMR (600 MHz,
CDCl3, 258C, TMS): d=2.06 (s, 12H; 6 ꢂ CH2), 6.57 (s, 4H; CHphenol),
3-[4-(4-{4-[3-Oxo-1-(2-oxo-2-phenylethyl)-3-phenylpropyl]phenyl}bicyclo-
A
(16):
1,4-Bis(4-
ACHTUNGTRENNUNG
none (1.32 g, 11.0 mmol) were dissolved in 95% aqueous ethanol, heated
to 658C, treated with aqueous KOH (194 mg 85% KOH, 2.94 mmol, in
1.76 mL distilled water), heated to reflux for 5 h, allowed to cool down
and poured into CHCl3 (200 mL). The organic phase was washed with
distilled water (3ꢂ150 mL), dried with Na2SO4, evaporated and purified
by column separation (silica gel, CHCl3/toluene 1:1). Yield: 188 mg
(246 mmol, 44%) of a yellowish solid. Rf (silica gel, CHCl3/toluene 1:1)=
0.09; 1H NMR (600 MHz, CDCl3, 258C, TMS): d=1.89 (s, 12H;
7.11 (t, 3J
3,3’-CHphenyl), 7.29 (d, 3J
20H; CHphenyl), 7.61 (d, 3J
N
ACHTUNGTREN(NGNU H,H)=7.7 Hz, 8H;
AHCTUNGTRENNUNG
CH2(bicycloctane)), 3.41 (ddd, 3J
(H,H)=43.1, 4J
E
N
(H,H)=8.5 Hz, 4H; CHphenyl bicyclooctane), 7.85 (d,
ꢀ
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ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!

The Concept of Compensating Dipoles
FULL PAPER
3J
(H,H)=8.5 Hz, 4H; CHphenyl bicyclooctane), 8.06 ppm (s, 4H; CHpyridinium);
125.3, 127.0, 127.2, 127.5, 127.9, 129.0, 129.1, 130.2, 130.6, 131.1, 134.1,
140.8, 156.3, 156.4, 156.7 ppm; IR (ATR): n˜ =3051.4 (w), 2961.4 (w),
1618.2 (m), 1597.0 (m), 1533.5 (w), 1491.9 (m), 1466.8 (m), 1436.9 (m),
1359.1 (w), 1286.5 (w), 1246.3 (w), 1182.0 (w), 1114.1 (w), 1074.5 (w),
1028.1 (w), 1008.2 (w), 993.4 (w), 893.4 (w), 842.6 (w), 799.7 (w), 776.1
(w), 756.7 (m), 733.9 (w), 694.1 (s), 659.9 (w), 628.9 (w), 613.9 cmꢀ1 (w);
UV/Vis (CHCl3): lmax (e)=374 (9900), 714 nm (6800); MS (FAB+): m/z
(%): 1215 (1) [2M++H], 624 (5) [M++OH], 608 (100) [M++H], 592 (5)
[M+ꢀCH3]; HRMS: m/z calcd for C45H38NO: 608.2953; found: 608.2957;
D=0.0004; elemental analysis calcd (%) for C45H37NO·H2O (625.8): C
86.37, H 6.28, N 2.24; found: C 86.96, H 6.13, N 2.26.
ꢀ
13C NMR (150 MHz, CDCl3, 258C, TMS): d=32.4, 35.6, 125.2, 125.5,
127.2, 127.4, 127.6, 128.0, 128.9, 129.0, 129.1, 130.2, 130.5, 131.4, 133.9,
140.3, 153.9, 154.5, 156.8 ppm; IR (ATR): n˜ =3054.4 (w), 2936.3 (w),
2857.8 (w), 1620.7 (m), 1607.9 (m), 1573.7 (w), 1544.4 (w), 1494.1 (w),
1465.8 (w), 1451.5 (w), 1419.8 (w), 1360.2 (w), 1313.0 (w), 1236.4 (w),
1159.9 (w), 1123.7 (w), 1077.5 (w), 1064.3 (w), 1047.0 (w), 1029.6 (w),
996.0 (w), 921.3 (w), 893.0 (w), 836.1 (w), 821.7 (w), 785.3 (w), 767.8 (m),
750.0 (m), 729.3 (w), 697.6 (s), 675.2 (w), 658.1 cmꢀ1 (w); UV/Vis
(CHCl3): lmax (Erel)=327.8 (1.00), 384.0 (0.25), 736.0 nm (0.18); HRMS:
m/z calcd for C90H69O2N2: 1209.5359; found: 1209.5298, D=ꢀ0.0061; ele-
mental analysis calcd (%) for C90H69O2N2·3H2O (1262.6): C 85.55, H
5.90, N 2.22; found: C 85.82, H 5.80, N 2.17.
4-(4-tert-Butylphenyl)-2,6-diphenyl-
pyrylium tetrafluoroborate: 4-tert-Butyl-
benzaldehyde (1.00 g, 6.16 mmol) and
acetophenone (1.60 g, 13.6 mmol) under
an argon atmosphere were heated at
568C, treated slowly dropwise with
POCl3 (1.50 g, 0.91 mL) and stirred at
658C for 2 h. The still warm, highly vis-
4,9-Bis(4-cyanophenyl)diamantane (20): 4,9-Di(4-iodophenyl)diamantane
(730 mg, 1.23 mmol) and CuCN (34 mg, 3.54 mmol) in DMF (14 mL)
were heated to reflux with stirring for 3 h, allowed to cool down, poured
into ice water/concentrated ammonia (60 mL, 10:1), stirred for 20 min,
and extracted with dichloromethane (3ꢂ100 mL). The combined organic
phases were washed with 2m aqueous HCl solution (100 mL), dried with
Na2SO4, evaporated and purified by column separation (silica gel, CHCl3/
isohexane 5:1). Yield: 367 mg (76%) of a colourless crystalline solid.
M.p.>3008C; Rf (silica gel, CHCl3)=0.67; 1H NMR (600 MHz, CDCl3,
cous mixture was dissolved in acetone (20 mL) and poured into ethanol
(50 mL), which was heated to reflux. The solution was concentrated to
about 35 mL by distillation, treated with 50% aqueous HBF4 (3 mL) and
allowed to cool down. The precipitate was collected by vacuum filtration,
washed with ethanol (80 mL) and distilled water (100 mL) and dried in
air at 1008C. Yield: 644 mg (23%) of a sun yellow solid. M.p. 2648C; IR
(ATR): n˜ =1630.1 (m), 1600.4 (m), 1509.9 (m), 1495.6 (s), 1438.1 (w),
1273.6 (w), 1250.2 (w), 1188.6 (w), 1028.9 (s), 998.0 (w), 957.7 (w), 884.6
258C, TMS): d=1.98–2.03 (m, 18H; CH2diamantane), 7.51 (d, 3J
8.7 Hz, 4H; CHarom.), 7.64 ppm (d, 3J
(H,H)=8.7 Hz, 4H; CHarom.);
ACHTUNGTRENNUNG(H,H)=
AHCTUNGTRENNUNG
13C NMR (150 MHz, CDCl3, 258C, TMS): d=34.8, 37.0, 42.9, 109.5,
119.1, 126.0, 132.0, 155.6 ppm; IR (ATR): n˜2917.3 (m), 2897.6 (m), 2878.4
(m), 2868.3 (m), 2847.7 (m), 2231.8 (m), 1605.5 (m), 1504.4 (m), 1461.5
(w), 1440.1 (w), 1398.4 (w), 1398.4 (w), 1376.0 (w), 1352.0 (w), 1294.4
(w), 1269.8 (w), 1179.5 (m), 1112.1 (w), 1075.1 (m), 1049.8 (m), 1020.5
(w), 985.8 (m), 954.0 (m), 836.1 (s), 797.2 cmꢀ1 (s); MS (EI+): m/z (%):
390.2 (100) [M+], 288.2 (10), 194.2 (12), 116.1 (10); HRMS: m/z calcd for
C28H26N2: 390.2096; found: 390.2087; D=ꢀ0.0009; elemental analysis
calcd (%) for C28H26N2 (390.2): C 86.12, H 6.71, N 7.17; found: C 85.73,
H 6.72, N 7.14.
(w), 834.4 (m), 777.0 (m), 744.1 (w), 721.0 (m), 685.4 cmꢀ1 (s); 1H NMR
3
(300 MHz, CDCl3, 258C, TMS): d=1.24 (s, 9H; CH3), 7.60 (d, J
8.7 Hz, 2H; CHarom.), 7.72–7.77 (m, 6H; CHphenyl), 8.32 (d, 3J
ACHTUNGTRENNUNG
A
8.7 Hz, 2H; CHarom.), 8.35–8.38 (m, 4H; CHphenyl), 8.63 ppm (s, 2H;
CHpyrylium); 13C NMR (75 MHz, CDCl3, 258C, TMS): d=30.7, 35.6, 114.0,
127.6, 128.5, 130.1, 130.4, 135.4, 160.9, 165.7, 170.1 ppm; UV/Vis (CHCl3):
lmax (Erel)=400.6 nm (1.00); MS (FAB+): m/z (%): 817.3 (6) [2M+
ꢀBF4], 730.3 (5), [2M+], 365.2 (100) [M+]; HRMS: m/z calcd for
C27H25O+: 365.1905; found: 365.1915, D=0.0010.
4,9-Bis(4-formylphenyl)diamantane (21): 4,9-Bis(4-cyanophenyl)diaman-
tane (20) (340 mg, 871 mmol) under an argon atmosphere was dispersed
in anhydrous dichloromethane (27 mL), cooled to 48C, treated dropwise
within 10 min with 1m DIBAL-H in hexane (5.44 mL), stirred at room
temperature for three hours, slowly poured into a 1:1 mixture of ice
water and 2m aqueous HCl solution (100 mL), stirred for 20 min, extract-
ed with chloroform (3ꢂ100 mL), dried with Na2SO4, evaporated and pu-
rified by column separation (silica gel, chloroform). Yield: 238 mg (95%)
of a colourless crystalline solid. M.p.>3008C. Rf (silica gel, CHCl3)=
0.49; 1H NMR (400 MHz, CDCl3, 258C, TMS): d=2.00 (m, 18H;
4-(4-tert-Butylphenyl)-2,6-diphenyl-N-(3,5-diphenyl-4-phenolate)pyridini-
um betaine (24): 4-(4-tert-Butylphenyl)-2,6-diphenylpyrylium tetrafluoro-
borate (500 mg, 1.10 mmol) and 4-amino-2,6-diphenylphenol (522 mg,
1.20 mmol) were dissolved in anhydrous ethanol (10 mL), which was
heated to reflux, treated with anhydrous sodium acetate (288 mg,
3.5 mmol), heated to reflux for 3 h (colour change from red to dark
blue), still hot, the solution was treated with 5% aqueous NaOH solution
(2.8 mL) and allowed to cool down. The precipitate was collected by
vacuum filtration, washed with 1% aqueous NaOH solution (50 mL) and
distilled water (50 mL), dried at 1008C and purified by column separa-
tion (silica gel, ethanol). Yield: 60 mg (10%) of a fir green solid. M.p.>
3008C; Rf (silica gel, ethanol)=0.20; 1H NMR (300 MHz, CDCl3, 258C,
CH2diamantane), 7.57 (d, 3J(H,H)=8.2 Hz, 4H; CHarom.), 7.85 (d, 3J
ACTHNUTRGENNUG ACHTUNGTRENNUNG(H,H)=
8.3 Hz, 4H; CHarom.), 9.99 ppm (s, 2H; CHaldehyde); 13C NMR (100 MHz,
CDCl3, 258C, TMS): d=35.0, 37.1, 43.0, 125.8, 129.8, 133.0, 134.2, 157.5,
TMS): d=1.38 (s, 9H; CH3), 6.44 (s, 2H; CHphenol), 7.07 (tt, 3J
7.4, 4J(H,H)=1.4 Hz, 2H; CHphenyl), 7.14 (t, 3J
(H,H)=7.4 Hz, 4H;
CHphenyl), 7.33 (d, 3J
(H,H)=7.1 Hz, 4H; CHphenyl), 7.35–7.38 (m, 10H;
CHphenyl), 7.62 (d, 3J(H,H)=8.6 Hz, 2H; CHtert-butylphenyl), 7.80 (d, 3J-
(H,H)=8.6 Hz, 2H; CHtert-butylphenyl), 8.02 ppm (s, 2H; CHpyridinium);
13C NMR (75 MHz, CDCl3, 258C, TMS): d=31.1, 35.2, 124.1, 125.2,
ACHTUNGTRNE(NUNG H,H)=
A
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
Chem. Eur. J. 2013, 00, 0 – 0
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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H. Langhals et al.
192.1 ppm; IR (ATR): n˜ =2920.6 (w), 2873.7 (w), 2850.9 (w), 1696.0 (m),
1685.5 (m), 1601.7 (m), 1568.8 (m), 1457.9 (w), 1441.9 (w), 1413.9 (w),
1395.5 (w), 1305.5 (w), 1266.3 (w), 1217.7 (m), 1190.4 (w), 1172.7 (m),
1113.0 (w), 1070.5 (m), 1051.4 (m), 981.7 (m), 827.8 (s), 797.2 (s), 730.1
(w), 714.8 (s), 664.5 cmꢀ1 (m); MS (EI+): m/z (%): 396.2 (100) [M+],
291.2 (9), 197.3 (42); HRMS: m/z calcd for C28H28O2: 396.2089; found:
396.2083, D=ꢀ0.0006.
4,4’-(4,9-Diphenyldiamantyl)bis-(2,6-diphenyl)pyrylium perchlorate (22):
Acetophenone (4.30 g, 4.48 mL) and 4,9-di(4-benzaldehydo)diamantane
(21) (179 mg, 451 mmol) were dispersed in a mixture of acetic acid
(1.8 mL) and acetic anhydride (0.9 mL), slowly dropwise treated with
60% aqueous HClO4 (0.54 mL), heated to reflux with stirring for 90 min
(turning to brown), allowed to cool, poured into diethyl ether (80 mL),
collected by vacuum filtration, plenty washed with diethyl ether, dried in
vacuo and stored under argon. The yellow solid was directly used for the
subsequent reaction without further purification because of its possibly
explosive properties (not further tested).
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4,4’-(4,9-Diphenyldiamanty-1-yl)-bis-[1-(3,5-diphenyl-4-phenolate)-2,6-di-
phenylpyridinium betaine] (23): 4,4’-(4,9-Diphenyldiamantyl)bis-(2,6-di-
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CH2diamantane), 7.14 (d, 3J
CHarom.), 7.29 (t, 3J(H,H)=7.4 Hz, 8H; CHphenyl), 7.34 (t, 3J
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
ACHTGNURTENUN(NG H,H)=7.3 Hz, 8H; CHphenyl), 7.25 (s, 4H;
7.5 Hz, 8H; CHphenyl), 7.40–7.42 (m, 12H; CHphenyl), 7.60 (d, 3J
8.8 Hz, 4H; CHarom.), 7.66–7.67 (m, 8H; CHphenyl), 7.95 (d, 3J
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
8.8 Hz, 4H; CHarom.), 8.18 ppm (s, 4H; CHpyridyl); 13C NMR (150 MHz,
CDCl3, 258C, TMS): d=34.8, 37.1, 43.0, 125.5, 126.6, 128.3, 128.5, 128.7,
129.0, 129.3, 129.4, 129.9, 130.1, 133.6, 155.5, 156.0, 156.8 ppm; IR (ATR):
n˜ =2880.9 (w), 1619.0 (m), 1596.9 (m), 1493.9 (w), 1463.9 (w), 1421.0 (m),
1354.7 (w), 1243.3 (w), 1119.0 (w), 1074.4 (w), 1027.9 (w), 985.0 (w),
887.0 (w), 839.9 (w), 760.8 (m), 743.1 (w), 732.9 (w), 698.0 (s), 674.1 (w),
659.0 cmꢀ1 (w); MS (FAB+): m/z (%): 1304.6 (3) [M++OH], 1288.8 (7)
[M++H], 1060.3 (2), 1043.7 (7), 644.5 (14), 552.5 (4); HRMS: m/z calcd
for C96H74N2O2: 1288.5862; found: 1288.5869, D= +0.0007.
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Acknowledgements
Financial support by the Fonds der Chemischen Industrie and the
CIPSM cluster Munich Center for Integrated Protein Science is gratefully
acknowledged. We thank Dr. Jeremy Dahl from Stanford University for
a gift of diamantane. P.B. thanks for a scholarship of the Bavarian state.
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The Concept of Compensating Dipoles
FULL PAPER
rante, R. Bozio, J. Phys. Chem. B 2010, 114, 882–893; d) C. Sissa, F.
Terenziani, A. Painelli, R. B. K. Siram, S. Patil, J. Phys. Chem. B
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[30] CCDC-918359 (20) contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
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Received: February 27, 2013
[28] K. Dimroth, C. Reichardt, Liebigs Ann. Chem. 1969, 727, 93–105.
Published online: && &&, 0000
Chem. Eur. J. 2013, 00, 0 – 0
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www.chemeurj.org
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H. Langhals et al.
How thin can it be? The extension of
the solvent influences was examined
by means of anti-collinear dipoles on
the basis of the solvent polarity scale
of a pyridinium-N-phenolatebetaine
dye (i.e., ET(30)), where no compensa-
tion effects were found (see figure). As
a consequence, solvent polarity effects
seem to be concentrated to a very thin
layer of a few hundred picometres.
Solvent Shells
H. Langhals,* P. Braun, C. Dietl,
P. Mayer ....................... &&&& — &&&&
How Many Molecular Layers of Polar
Solvent Molecules Control Chemistry?
The Concept of Compensating Dipoles
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www.chemeurj.org
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!