Synthesis, characterization, and saccharide binding studies of bile acid - Porphyrin conjugates

Article abstract of DOI:10.3390/12010013

Synthesis and characterization of bile acid-porphyrin conjugates (BAPs) are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studi

Full text of DOI:10.3390/12010013

Molecules 2007, 12, 13-24
molecules
ISSN 1420-3049
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Full Paper
Synthesis, Characterization, and Saccharide Binding Studies of
Bile Acid − Porphyrin Conjugates
Juha Koivukorpi 1,†, Elina Sievänen 1,‡, Erkki Kolehmainen 1,* and Vladimír Král 2,3
1 Department of Chemistry, P.O. Box 35, FIN-40014, University of Jyväskylä, Finland; †E-mail:
jkkorpi@jyu.fi; ‡E-mail: elvirtan@jyu.fi
2 Institute of Chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic. E-mail:
vladimir.kral@vscht.cz
3 Zentiva Ltd., Prague, Czech Republic
* Author to whom correspondence should be addressed. E-mail: ekolehma@jyu.fi
Received: 17 November 2006; in revised form: 2 January 2007 / Accepted: 4 January 2007 /
Published: 5 January 2007
Abstract: Synthesis and characterization of bile acid-porphyrin conjugates (BAPs) are
reported. Binding of saccharides with BAPs in aqueous methanol was studied by
monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although
these studies clearly showed absorbance changes, suggesting quite high if non-selective
binding, the mass spectral studies do not unambiguously support these results.
Keywords: Bile acids, porphyrin, saccharide, visible spectroscopy, 1H-NMR, ESI MS.
Introduction
Bile acids possess a large number of applications in pharmaceutical and supramolecular chemistry,
as recently reviewed [1]. For example, bile acids are potential carriers for liver specific drugs and they
can be used as cholesterol level lowering agents [2]. Bile acids and their derivatives have also been
used for treatment of bile acid deficiency and liver diseases [3]. Furthermore, Matile et al. have
reported that some oligomeric bile acid derivatives can act as carriers − folding like umbrellas around
hydrophilic guests [4]. More recently, Janout et al. have reported bile acid derived molecular umbrella-
assisted transport of an oligonucleotide across cholesterol-rich phospholipid bilayers [5]. Porphyrin

Molecules 2007, 12
14
conjugates are potential supramolecular hosts as revealed by their use in saccharide sensing [6,7,8,9],
anion binding [10,11,12], and nucleotide recognition in protic media [13,14]. We have recently
reported the synthesis and characterization, as well as nucleotide binding studies, of tetrameric cholic
acid-porphyrin conjugates 1-4 (Figure 1) [15].
The design of these conjugates stems from the idea that four bile acid moieties (recognition arms of
the conjugate) are attached to one tetratolylporphyrin unit (signaling group of the conjugate) via an
alkylammonium amido linkage [15]. In addition to hydrogen bonding, these structures can also provide
binding mechanisms via π-stacking and coulombic interactions. All these interaction mechanisms
increase the functionality and capability of these conjugates to interact with different biologically
active substrates. As an example of the medicinal significance of porphyrin derivatives, their use as
sensitizers in photodynamic therapy can be mentioned [16].
The principal aim of this work was to study the suitability of bile acid-porphyrin conjugates as
saccharide receptors. However, owing to some contradictory results, as described below, this problem
remains unsolved and requires further studies, probably with other experimental techniques.
Figure 1. Structures of 1-16.
H
H
N
N+
N+
N
(
(
O
O
OH
OH
OH
b
OH
a
c
OH
OH
H
H
N+
N
N
N+
(
R2
(
R1
R1
O
O
OH
OH
R2
d
OH
N
H
OH
N
N
H
N
H
H
N+
N+
N
N
(
(
R2
O
O
R1
R1
R2
OH
OH
f
e
OH
OH
H
H
N+
N+
N
N
(
(
O
O
g
h
OH
OH
R1 R2
R1 R2
1
2
3
4
5
6
7
8
a
-H
b
-H
c
-H
d
-H
-H
a
-H
b
-H
c
-H
d
9
e
-H
e
-H
f
-H
g
-H
h
10 -H
11
12 -H
13
14 -H
15
16 -H
f
g
h

Molecules 2007, 12
15
Results and Discussion
Synthesis and characterization
Conjugates 5-16 (Figure 1) were prepared according to the previously reported procedure for the
synthesis of 1-4 (Scheme 1) [15]. In designing these structures we were especially interested in varying
the number and position of hydroxyls in monohydroxy (lithocholic), dihydroxy (deoxycholic and
chenodeoxycholic), and trihydroxy (cholic) bile acids, thus forming a smoothly changing structural
continuum in this series of receptors.
Scheme 1. Synthesis of 5.
OH
HO
O
Br-
N+
H
N
OH
OH
OH
O
N+ Br-
NH
OH
N
H
HO
O
N
N
O
H
N
a
70-80 %
HN
O
N
OH
N
H
HO
N+
Br-
O
N+
Br-
OH
N
b
H
HO
80-90 %
OH
HO
Reagents and conditions: (a) (i) N,N’-di-iso-propylcarbodiimide, N-hydroxysuccinimide, CHCl3,
r.t. 2 h; (ii) 2-N,N-dimethylaminoethylamine, pyridine, CHCl3, r.t, 1 day; (b) H2TPP(p-BrCH2)4,
CHCl3, reflux, 1 day.
1
The H-NMR spectral characterization of 5-16 was based on our results on bile acids and their
derivatives [1], as well as on cholic acid-porphyrin conjugates 1-4 reported before [15]. As in the case
of cholic acid derivatives 1-4 [15], the C18 and 19 angular methyls of the steroidal moieties in 5-16 are
strongly shielded, due to the anisotropic ring current effect of the BAP porphyrin core. However, the
separation of the angular methyl signals into two clearly resolved resonances with 1:3 intensity ratio, as
seen in the case of compound 1, was not that clear in 5-16. For example, in 5 the shift difference
between the C18 and 19 methyls was only 0.04 ppm, while in 1 it was 0.2 ppm [15]. In compound 6
four resonances in a 1:1:1:2 intensity ratio exist in the most shielded spectral range (from 0.3 to -0.8
ppm). This means that different BAPs possess different conformational characteristics, depending on

Molecules 2007, 12
16
how many hydroxyls are present in the steroidal moiety and whether they are linked with a m- or p-
1
13
tolyl-derived porphyrin core. Many BAPs displayed complex H- and C-NMR spectra in CD3OD at
30 °C, owing to a conformational equilibrium of the steroidal moieties. However, the 1H-NMR spectra
1
simplified remarkably when measured in DMSO-d6 at elevated temperatures. As an example the H-
NMR spectra of 8 in DMSO-d6 at 30 °C and at 130 °C are shown in Figure 2. A subsequent
remeasurement of 8 at 30 °C afforded the same spectrum which was observed before heating, thus
revealing the thermal stability of the receptor.
Figure 2. 1H-NMR spectra of 8 in DMSO-d6 measured at 30 °C and 130 °C.
Binding studies
Binding studies with BAPs 1-12 were conducted using three common saccharides, viz.
D(+)-
glucose, (+)-sucrose, and maltotriose, and also for sialic acid (Figure 3) with 1-4, by detecting the
D
changes in the visible absorption (419-421 nm) of the porphyrin-moiety of the BAP.
Figure 3. Structures of the saccharides used.
O
O
HO
HO
HO
OH
HO
HO
HO
HO
HO
HO
HO
O
HO
O
HO
O
O
O
O
O
O
O
O
OH
OH
OH
OH
HO
NH
HO
OH
HO
OH HO
HO
OH
HO
(+)-Sucrose
D
OH
OH HO
OH
(+)-Glucose
Maltotriose
D
Sialic acid

Molecules 2007, 12
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These experiments have been performed in a 2:1 (v:v) water-methanol solvent mixture because in a
pure aqueous medium the aggregation tendency of this kind of conjugates is obvious [16]. In spite of
the addition of methanol, we were unable to study the binding in lithocholyl derivatives 13-16 owing to
their poor solubility in this solvent system, therefore we are only reporting the synthesis and spectral
characterization of the latter compounds. Before UV/Vis spectral measurements, the BAP and
saccharide solutions were adjusted to pH 7.4 with dilute hydrochloric acid and sodium hydroxide
solutions. It was previously shown that chloride and other inorganic small anions do not cause any
changes in the visible absorption of BAPs 1-4 [15]. Titration curves (absorbance as a function of
[S]/[BAP]) showed that all saccharides tested had clear influences on the absorbance levels of 1-12.
Titrations were performed by adding a solution containing both BAP (2.3 µM) and saccharide (92 µM)
into the BAP solution (2.3 µM), covering the range of 0-20 equivalents of saccharide. Measurements
were carried out at the wavelength λmax = 419-421 nm depending on the BAPs’ Soret maximum.
Binding constants (Ka) can be calculated from the absorbance changes of the porphyrins by equation 1
using the Soret band maximum (∆A) and assuming 1:1 stoichiometry [17].
1
1
1
(1)
=
+
∆A Ka
[S
](
∆A ∞
)
(
∆A
)
∞
where [S] is the saccharide concentration and (∆A)∞ is the extrapolated absorbance change where
saccharide concentration goes to infinity. In analyzing the titration curves, their Job’s plots did not
show any definite stoichiometries for BAP and saccharide interactions. Attempts to fit experimental
data to a 1:1 model gave very high apparent binding constants (Figure 4).
Figure 4. Titration curve of 1 with maltotriose. Dots denote measured data points and the
solid line is a calculated curve based on a 1:1 binding model. Insert: Job’s plot of the
titration of [maltotriose]/[1].
Figure 4 shows a typical titration curve of absorbance as a function of [maltotriose]/[1], and its
corresponding Job’s plot. The calculated line follows the measured points well at lower saccharide

Molecules 2007, 12
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concentrations but deviates significantly from them when the absorbance starts to rise at higher
concentrations. Reasons for that phenomenon might be the self-aggregation of saccharide molecules at
high saccharide concentrations or conformational changes of BAP. Titration of 1 with glucose in
DMSO was performed to check whether an aprotic solvent has some effect to the titration curve, but a
similar increase of absorbance was detected also in that case.
ESI mass spectrometric measurements
Because the results of the visible absorption spectral studies were somewhat confusing, ESI-TOF
mass spectrometric measurements were also carried out. Equal volumes of equimolar (50 µM)
solutions of the BAP and each individual saccharide, viz. D(+)-glucose, D(+)-sucrose, and maltotriose,
were prepared. The same solvent mixture (H2O-MeOH 2:1 v:v) as in the UV/Vis experiments was used
in order to enable comparison between the results. In general, the intensities of the ions of the BAP-
saccharide adducts were weak in comparison with the spectral base peak. Comparison between mass
spectra measured for pure receptor 1 and 1 with glucose or sucrose, revealed no explicit differences.
With maltotriose additional weak signals were detected in the spectrum measured for the mixture of 1
and the saccharide, compared to the spectrum measured for the pure 1. These additional signals were
identified to correspond to the multiply charged ions [1 + maltotriose]4+, [1 + maltotriose + Br-]3+, and
[1 + maltotriose + 2Br-]2+. An additional experiment performed for a 1:1:1:1 mixture of 1 and all three
saccharides supported the above observations. No ions resulting from adduct formation between
glucose or sucrose with 1 could be identified. However, weak multiply charged ions corresponding to
maltotriose adducts of 1 were detected. An example is shown in Figure 5.
Figure 5. Partial ESI-TOF mass spectra for a) 1:1:1:1 mixture of receptor 1 and three
saccharides [
D(+)-glucose, D(+)-sucrose, maltotriose] and b) pure receptor 1 measured in
H2O-MeOH (2:1 v:v) solution.

Molecules 2007, 12
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Thus, these mass spectral measurements did not unambiguously support the above mentioned high
binding hypothesis drawn from the visible spectral studies. Although ESI MS results did not clearly
1
reveal high binding, H-NMR spectral studies of 5 with glucose have been performed to clarify the
possible interaction site of the saccharide with bile acid-porphyrin conjugate (Figure 6). In DMSO-d6
glucose shows a spectrum where all protons are well resolved. For a 1:1 [glucose]:[5] mixture in
DMSO-d6 all glucose hydroxyl signals merge into one signal owing to a fast exchange in NMR time
scale. Because no significant ASIS (aromatic solvent induced shift)-effect due to the aromatic
porphyrin-moiety is observed in the remaining resolved glucose protons, this merging is most likely
due to traces of acidic impurities and cannot be construed as proof of any host-guest interaction.
Figure 6. 1H-NMR spectra of
(+)-glucose (top) in DMSO-d6.
D(+)-glucose (bottom), 5 (middle), and 5 +
D
Conclusions
Novel bile acid-porphyrin conjugates (BAPs) have been synthesized and characterized. Binding of
four common representatives of mono-, di-, and trisaccharides (S), viz. (+)-glucose, sialic acid, (+)-
D
D
sucrose and maltotriose in these conjugates has been studied by detecting changes in the visible
absorption spectra of the porphyrin moieties as a function of [S]/[BAP]. The Job’s plots of these
titrations did not reveal any definite stoichiometry for the saccharide binding. Also, the apparent
binding constants calculated by assuming 1:1 stoichiometry, although being quite high, did not show
any significant selectivity. In contrast with the hypothesis based on the visible absorption spectral
studies, ESI-MS investigations did not unambiguously support the notion of high binding between the
saccharides and BAPs. Additional work is needed to clarify the basis of this discrepancy between the
results obtained with different spectral techniques. Syntheses of related bile acid derivatives with small
aromatic cores are in progress. More comprehensive MS studies (not only at a 1:1 molar ratio) could

Molecules 2007, 12
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also be useful. Nevertheless, and in spite of their somewhat unclear saccharide binding properties,
these BAPs might be useful sensitizers in photodynamic therapy and in distinguishing between
cancercerous and normal cells. These studies are also in progress.
Acknowledgements
The authors acknowledge Special Laboratory Technicians Mirja Lahtiperä and Reijo Kauppinen for
their help in running the ESI TOF mass and NMR spectra. E.S. wishes to thank the Academy of
Finland for financial support (project no. 7105950). This work was funded by a grant from the Grant
Agency of the Czech Republic (Grant No. 203/06/1038) and supported in part by project LC06077
awarded by the Ministry of Education of the Czech Republic MSM.
Experimental
General
NMR experiments were run on a Bruker Avance DRX 500 FT NMR spectrometer equipped with a
z-gradient accessory and a 5 mm diameter inverse detection probehead working at 500.13 MHz for
1
proton spectra. Unless otherwise stated spectra were recorded at 30 °C in CD3OD. H-NMR chemical
shifts are referenced to the solvent signals of CHD2OD [δ(1H) = 3.31] and DMSO-d5 [δ(1H) = 2.50
ppm] from internal TMS. All NMR acquisition and processing parameters are available from E.K. on
request. UV/Vis measurements were performed with a Perkin Elmer Lambda 25 UV/VIS spectrometer
using a 1.0 cm glass cuvette. Mass spectrometric measurements were performed using a Micromass
LCT time of flight (TOF) mass spectrometer with electrospray ionization (ESI). Elemental analysis
was performed using a VarioEL III elemental analyzer. All reagents and solvents (purity ≥ 96% or
better) were purchased from Sigma-Aldrich or Fluka and used without further purification. Receptors
5-16 were synthesized by a previously reported procedure [15]. For the analytical and spectral data of
the compounds 5,10,15,20-tetrakis[dimethyl (3
ammoniomethylphen-4-yl] porphyrin tetrabromide (1), 5,10,15,20-tetrakis[dimethyl (3
trihydroxy-5 -cholan-24-amidoethyl)ammoniomethylphen-3-yl] porphyrin tetrabromide (2), 5,10,15,
20-tetrakis[dimethyl (3 ,7 ,12 -trihydroxy-5 -cholan-24-amidopropyl)ammoniomethylphen-4-yl]
porphyrin tetrabromide (3), and 5,10,15,20-tetrakis-[dimethyl (3 ,7 ,12 -trihydroxy-5 -cholan-24-
α
,7
α
,12
α
-trihydroxy-5
β
-cholan-24-amidoethyl)-
α
,7α,12
α-
β
α
α
α
β
α
α
α
β
amidopropyl)ammoniomethylphen-3-yl] porphyrin tetrabromide (4) see refs. [15,18].
Analytical and spectral data for 5-16.
5,10,15,20-Tetrakis[dimethyl (3α,12α-dihydroxy-5β-cholan-24-amidoethyl)ammoniomethylphen-4-yl]
o
1
porphyrin tetrabromide (5): Yield 77 %; m.p. > 300 C (decomp.); H-NMR: δ = 0.16−0.22 (18H),
0.23−2.40 (130H), 3.43 (24H, d), 3.70−3.90 (14H), 3.86 (4H, m), 3.92 (4H, m), 4.80 (8H, s), 5.00 (8H,
s), 8.10 (8H, d), 8.39 (8H, d), 8.95 (8H, br); MS: m/z = 629 [M]4+, 866 [M+Br]3+, 1338 [M+2Br]2+;
M.W. (C160H234N12O12Br4) = 2837.34; Elemental analysis: calcd. (%) for C160H234N12O12Br4 + CHCl3:
C, 65.40; H, 8.01; N, 5.68. Found C, 65.46; H, 8.10; N, 5.52.

Molecules 2007, 12
21
5,10,15,20-Tetrakis[dimethyl(3α,12α-dihydroxy-5β-cholan-24-amidoethyl)ammoniomethylphen-3-yl]
o
1
porphyrin tetrabromide (6): Yield 87 %; m.p. > 300 C (decomp.); H-NMR: δ = -0.84 (2H, s), -0.15
(4H, s), -0.10 (4H, s), 0.20−2.30 (136H), 3.36 (24H, d), 3.40−3.60 (8H), 3.65 (8H, m), 3.81 (8H, m),
4.80 (8H, s), 4.96 (8H, s), 8.01 (4H, d), 8.12 (4H, d), 8.45 (8H, m), 8.89 (8H, br); MS: m/z = 629
[M]4+, 866 [M+Br]3+, 1338 [M+2Br]2+; M.W. (C160H234N12O12Br4) = 2837.34; Elemental analysis:
calcd (%) for C160H234N12O12Br4: C, 67.73; H, 8.31; N, 5.92. Found C, 67.40; H, 8.54; N, 5.37.
5,10,15,20-Tetrakis[dimethyl (3α,12α-dihydroxy-5β-cholan-24-amidopropyl)ammoniomethylphen-4-
o
1
yl]porphyrin tetrabromide (7): Yield 83 %; m.p. > 300 C (decomp.); H-NMR: δ = -1.00 − -0.70
(4H), -0.66 (6H, s), 0.00−2.40 (142H), 3.39 (24H, d), 3.35 (12H, m), 3.50−3.70 (14H), 4.80 (8H, s),
4.85 (8H, s), 8.04 (8H, d), 8.39 (8H, d), 8.94 (8H, br); MS: m/z = 643 [M]4+, 885 [M+Br]3+, 1367
[M+2Br]2+; M.W. (C164H242N12O12Br4) = 2893.45; Elemental analysis: calcd (%) for
C164H242N12O12Br4 + 1.5 CHCl3: C, 64.70; H, 7.99; N, 5.47. Found C, 64.56; H, 8.12; N, 5.35.
5,10,15,20-Tetrakis[dimethyl (3α,12α-dihydroxy-5β-cholan-24-amidopropyl)ammoniomethylphen-3-
yl] porphyrin tetrabromide (8): Yield 95%; m.p. > 300 oC (decomp.); 1H-NMR: δ = -0.33 (2H, s), 0.00
(3H, s), 0.06 (2H, s), 0.17 (2H, s), 0.30 (4H, s), 0.33−2.30 (150H), 3.31 (24H, s), 3.45 (5H, m), 3.59
(10H, m), 4.80 (8H, s), 4.92 (8H, s), 8.02 (4H, d), 8.09 (4H, d), 8.43 (8H, m), 8.92 (8H, br); MS: m/z =
643 [M]4+, 884 [M+Br]3+, 1367 [M+2Br]2+; M.W. (C164H242N12O12Br4) = 2893.45; Elemental analysis:
calcd (%) for C164H242N12O12Br4 + CHCl3: C, 65.78; H, 8.13; N, 5.58. Found C, 65.51; H, 8.15; N,
5.31.
5,10,15,20-Tetrakis[dimethyl (3α,7α-dihydroxy-5β-cholan-24-amidoethyl)ammoniomethylphen-4-yl]
o
1
porphyrin tetrabromide (9): Yield 70 %; m.p. > 300 C (decomp.); H-NMR: δ = 0.04−0.22 (18H),
0.30−2.40 (132H), 3.44 (24H, d), 3.66 (12H, m), 3.85 (4H, m), 3.94 (4H, m), 4.80 (8H, s), 5.01 (8H, s),
8.11 (8H, d), 8.39 (8H, d), 8.94 (8H, br); MS: m/z = 629 [M]4+, 865 [M+Br]3+, 1337 [M+2Br]2+; M.W.
(C160H234N12O12Br4) = 2837.34; Elemental analysis: calcd (%) for C160H234N12O12Br4 + 1.5 CHCl3: C,
64.31; H, 7.85; N, 5.57. Found C, 64.54; H, 7.95; N, 5.76.
5,10,15,20-Tetrakis[dimethyl (3α,7α-dihydroxy-5β-cholan-24-amidoethyl)ammoniomethylphen-3-yl]
porphyrin tetrabromide (10): Yield 81 %; m.p. > 300 oC (decomp.); 1H-NMR: δ = -0.76 (2H, s), -0.31
(2H, s), -0.01 (2H, s), 0.03 (4H, s), 0.20 (6H, s), 0.30−2.20 (136H), 3.34 (24H, d), 3.50−3.80 (18H),
4.80 (8H, s), 4.91 (8H, d), 7.99 (4H, d), 8.09 (4H, d), 8.42 (8H, m), 8.90 (8H, br); MS: m/z = 629
[M]4+, 866 [M+Br]3+, 1338 [M+2Br]2+; M.W. (C160H234N12O12Br4) = 2837.34; Elemental analysis:
calcd (%) for C160H234N12O12Br4 + CHCl3: C, 65.40; H, 8.01; N, 5.68. Found C, 65.73; H, 8.12; N,
5.65.
5,10,15,20-Tetrakis[dimethyl (3α,7α-dihydroxy-5β-cholan-24-amidopropyl)ammoniomethylphen-4-yl]
porphyrin tetrabromide (11): Yield 94 %; m.p. > 300 oC (decomp.); 1H-NMR: δ = -1.04 (2H, s), -0.93
(1H, s), -0.80 − -0.60 (8H), 0.10−0.23 (8H), 0.32 (9H, s), 0.33−2.40 (135H), 3.39 (24H, d), 3.50−3.70
(15H), 4.80 (8H, s), 4.96 (8H, d), 8.04 (8H, d), 8.39 (8H, d), 8.93 (8H, br); MS: m/z = 643 [M]4+, 884

Molecules 2007, 12
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[M+Br]3+, 1366 [M+2Br]2+. M.W. (C164H242N12O12Br4) = 2893.45; Elemental analysis: calcd (%) for
C164H242N12O12Br4 + 0.5 CHCl3: C, 66.91; H, 8.28; N, 5.69. Found C, 66.43; H, 8.29; N, 5.54.
5,10,15,20-Tetrakis[dimethyl (3α,7α-dihydroxy-5β-cholan-24-amidopropyl)ammoniomethylphen-3-yl]
o
1
porphyrin tetrabromide (12): Yield 92 %; m.p. > 300 C (decomp.); H-NMR: δ = -0.31 (2H, s), 0.00
(6H, s), 0.10−0.23 (158H), 3.30 (24H, d), 3.50−3.70 (12H), 4.80 (8H, s), 4.89 (8H, d), 8.01 (4H, d),
8.09 (4H, d), 8.43 (8H, m), 8.92 (8H, br); MS: m/z = 643 [M]4+, 884 [M+Br]3+, 1366 [M+2Br]2+;
M.W. (C164H242N12O12Br4) = 2893.45; Elemental analysis: calcd (%) for C164H242N12O12Br4 + CHCl3:
C, 65.78; H, 8.13; N, 5.58. Found C, 65.48; H, 8.15; N, 5.23.
5,10,15,20-Tetrakis[dimethyl (3α-hydroxy-5β-cholan-24-amidoethyl)ammoniomethylphen-4-yl]
o
1
porphyrin tetrabromide (13): Yield 71 %; m.p. > 300 C (decomp.); H-NMR: δ = 0.11−0.23 (17H),
0.30−2.40 (141H), 3.44 (24H, d), 3.66 (8H, m), 3.86 (4H, m), 3.94 (4H, m), 4.80 (4H, s), 5.01 (8H, d),
8.11 (8H, d), 8.39 (8H, d), 8.92 (8H, br); MS: m/z = 613 [M]4+, 844 [M+Br]3+, 1306 [M+2Br]2+; M.W.
(C160H234N12O8Br4) = 2773.34; Elemental analysis: calcd (%) for C160H234N12O8Br4 + 0.5 CHCl3: C,
68.05; H, 8.34; N, 5.93. Found C, 67.98; H, 8.42; N, 5.86.
5,10,15,20-Tetrakis[dimethyl (3α-hydroxy-5β-cholan-24-amidoethyl)ammoniomethylphen-3-yl]
porphyrin tetrabromide (14): Yield 73 %; m.p. > 300 oC (decomp.); 1H-NMR: δ = -0.76 (1H, s), -0.18
(2H, s), -0.04 (3H, s), 0.06 (3H, s), 0.20−2.30 (141H), 3.36 (24H, d), 3.40−3.60 (8H), 3.66 (8H, m),
3.79 (8H, m), 4.80 (4H, s), 4.96 (8H, d), 7.99 (4H, d), 8.11 (4H, d), 8.38 (4H, m), 8.46 (4H, m), 8.90
(8H, br); MS: m/z = 613 [M]4+, 845 [M+Br]3+, 1306 [M+2Br]2+; M.W. (C160H234N12O8Br4) = 2773.34;
Elemental analysis: calcd (%) for C160H234N12O8Br4 + CHCl3: C, 66.85; H, 8.19; N, 5.81. Found C,
66.63; H, 8.16; N, 5.60.
5,10,15,20-Tetrakis[dimethyl (3α-hydroxy-5β-cholan-24-amidopropyl)ammoniomethylphen-4-yl]
porphyrin tetrabromide (15): Yield 79 %; m.p. > 300 oC (decomp.); 1H-NMR: δ = -0.83 (3H, m), -0.61
(6H, s), 0.00−2.40 (161H), 3.38 (24H, d), 3.54 (12H, m), 4.80 (4H, s), 4.95 (8H, d), 8.04 (8H, d), 8.38
(8H, d), 8.93 (8H, br); MS: m/z = 627 [M]4+, 863 [M+Br]3+, 1334 [M+2Br]2+; M.W.
(C164H242N12O8Br4) = 2829.45; Elemental analysis: calcd (%) for C164H242N12O8Br4 + 0.5 CHCl3: C,
68.39; H, 8.46; N, 5.82. Found C, 68.51; H, 8.60; N, 5.73.
5,10,15,20-Tetrakis[dimethyl (3α-hydroxy-5β-cholan-24-amidopropyl)ammoniomethylphen-3-yl]
porphyrin tetrabromide (16): Yield 91 %; m.p. > 300 oC (decomp.); 1H-NMR: δ = -0.50−2.40 (168H),
3.31 (24H, d), 3.40−3.70 (14H), 4.80 (4H, s), 4.91 (8H, m), 8.00 (4H, d), 8.08 (4H, d), 8.41 (8H, m),
8.93 (8H, br); MS: m/z = 627 [M]4+, 863 [M+Br]3+, 1334 [M+2Br]2+; M.W. (C164H242N12O8Br4) =
2829.45; Elemental analysis: calcd. (%) for C164H242N12O8Br4 + 0.5 CHCl3: C, 68.39; H, 8.46; N, 5.82.
Found C, 68.50; H, 8.62; N, 5.61.

Molecules 2007, 12
23
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437-441. Supramol. Chem. in press.
Sample Availability: Samples of the compounds 1-16 are available from authors.
© 2007 by MDPI (http://www.mdpi.org). Reproduction is permitted for noncommercial purposes.