Synthesis and characterization of novel dendritic compounds bearing a porphyrin core and cholic acid units using "click chemistry"

Article abstract of DOI:10.1016/j.dyepig.2016.04.047

Four novel dendritic molecules bearing a porphyrin core and peripheral cholic acid units (TPPh(Zn) Tetra-CA, TPPh(2H) Tetra-CA, TPPh(Zn) Octa-CA and TPPh(2H) Octa-CA) have been synthesized by the "click chemistry" approach, using azide-alkyne couplings. These compounds are fully characterized by ¹H and ¹³C NMR spectroscopy and MALDI-TOF. The optical properties of the dendronized porphyrins are studied by absorption and fluorescence spectroscopy in different solvents, in order to study the amphiphilic properties of the cholic acid units in combination with the optical response of the porphyrin unit. After complexation with Zn, the metallated porphyrins (TPPh(Zn) tetra-CA and TPPh(Zn) octa-CA) tend to form J-aggregates in solvents of different polarity, whereas the free base porphyrins TPPh(2H) tetra-CA and TPPh(2H) octa-CA behaved differently. The aggregation phenomenon has been investigated by varying the polarity of the environment, temperature and metallation.

Full text of DOI:10.1016/j.dyepig.2016.04.047

Dyes and Pigments 132 (2016) 110e120
Contents lists available at ScienceDirect
Dyes and Pigments
journal homepage: www.elsevier.com/locate/dyepig
Synthesis and characterization of novel dendritic compounds bearing
a porphyrin core and cholic acid units using “click chemistry”
a
b
a
a
ꢀ
Edgar Aguilar-Ortíz , Nicolas Levaray , Mireille Vonlanthen , Eric G. Morales-Espinoza ,
Yareli Rojas-Aguirre c, Xiao Xia Zhu b **, Ernesto Rivera a
Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior Ciudad Universitaria, CP 04510, Mexico City,
,
, *
a
ꢀ
ꢀ
Mexico
b
ꢀ
ꢀ
ꢀ
ꢀ
Departement de Chimie, Universite de Montreal, CP 6128, Succursale Centre-ville, Montreal, QC, H3C 3J7, Canada
c
ꢀ
ꢀ
Facultad de Química, Universidad Nacional Autonoma de Mexico, Circuito Exterior Ciudad Universitaria, CP 04510, Mexico City, Mexico
a r t i c l e i n f o
a b s t r a c t
Article history:
Four novel dendritic molecules bearing a porphyrin core and peripheral cholic acid units (TPPh(Zn)
Tetra-CA, TPPh(2H) Tetra-CA, TPPh(Zn) Octa-CA and TPPh(2H) Octa-CA) have been synthesized by the
“click chemistry” approach, using azide-alkyne couplings. These compounds are fully characterized by 1H
and 13C NMR spectroscopy and MALDI-TOF. The optical properties of the dendronized porphyrins are
studied by absorption and fluorescence spectroscopy in different solvents, in order to study the
amphiphilic properties of the cholic acid units in combination with the optical response of the porphyrin
unit. After complexation with Zn, the metallated porphyrins (TPPh(Zn) tetra-CA and TPPh(Zn) octa-CA)
tend to form J-aggregates in solvents of different polarity, whereas the free base porphyrins TPPh(2H)
tetra-CA and TPPh(2H) octa-CA behaved differently. The aggregation phenomenon has been investigated
by varying the polarity of the environment, temperature and metallation.
Received 16 February 2016
Received in revised form
19 April 2016
Accepted 26 April 2016
Available online 27 April 2016
Keywords:
Porphyrin
Cholic acid
Click chemistry
Optical properties
Aggregation
© 2016 Elsevier Ltd. All rights reserved.
1. Introduction
coordination chemistry either at the tetrapyrrolic core or the pe-
riphery give rise to a large number of porphyrin derivatives with
Porphyrins are macrocyclic molecules which attracted much
attention from researchers due to their importance in both natural
and artificial chemical and biochemical systems. From the biolog-
ical perspective, some classes of porphyrins and their metallic
complexes play a key role in essential biological processes such as
oxygen transport and photosynthesis [1,2]. In the fields of chem-
istry and materials science, they have been widely studied due to
their vast range of potential applications including catalysis, elec-
trocatalysis and photodynamic therapy when they are used as
building blocks to engineer light-responsive systems. Of special
interest are the nonlinear optical properties of the porphyrin ag-
gregates for energy transfer to design artificial photosynthetic
systems, molecular photonic wires and multiporphyrin arrays as
artificial light-harvesting antennas [3e5].
unique optical and electronic features. A variety of ligands have
been used to functionalize the porphyrin core, i.e., crown ethers,
phosphines and pyridines to name a few [1,5]. Moreover, the
porphyrin unit has been used as a core to design and synthesize
novel dendritic systems. In this case, the optoelectronic properties
can be tuned by modifying the structure of the dendrons, thus
extending the potential of porphyrin applications [6,7]. The fasci-
nating optical and electrochemical features of the porphyrin den-
drimers have inspired us to continue exploring them. We have been
working on the construction of dendritic systems by attaching
branches of different architectures to the porphyrin periphery. Very
recently, we reported the synthesis, photophysical and electro-
chemical properties of pyrene-dendronized porphyrins in order to
investigate the energy transfer (FRET) mechanisms in these sys-
tems [8e10]. The interesting outcomes of this work motivated us to
continue exploring the optical and photophysical properties of
different dendritic porphyrin constructs, as well as the FRET phe-
nomena which occur in them.
The chemical modifications at their meso positions and the
* Corresponding author.
** Corresponding author.
E-mail addresses: julian.zhu@umontreal.ca (X.X. Zhu), riverage@unam.mx
(E. Rivera).
On the other hand, the steroid scaffold is a large and rigid non-
conjugated structure prone to a variety of chemical modifications to
http://dx.doi.org/10.1016/j.dyepig.2016.04.047
0143-7208/© 2016 Elsevier Ltd. All rights reserved.

E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
111
generate derivatives with a well-defined architecture. These com-
2.3. Synthesis of the dendritic molecules
pounds are suitable for the binding of polar species and therefore
may be potentially used in anion sensing [11]. In a previous work,
Vollmer and co-workers reported an energy transfer system based
on a bithienylporphyrin and an anthrylthiophene unit linked via a
rigid androstene bridge with the aim to investigate the influence of
distance, orientation and electronic communication between the
chromophores in intramolecular FRET processes. They found that
the steroid nucleus partially interrupted the energy transfer and
that may influence the parameters governing the efficiency of
2.3.1. Synthesis of 4-(prop-2-1-yloxy)benzaldehyde (1)
4-hydroxybenzaldehyde (5 g, 40 mmol) and propargyl bromide
(3.6 mL, 40 mmol) were reacted, with K2CO3 (8.28 g, 60 mmol) as
base and dry acetone (50 mL) as solvent, heating at 60 ꢀC for 24 h
(Fig. 1). The crude product was filtered and purified by column
chromatography using a mixture of hexanes: ethyl acetate (9:1) to
give the desired product (1), which was isolated as a pale yellow
solid (5.18 g, 32.3 mmol). Yield: 80%.
Forster-type FRET, which was assumed to be the most relevant
1H NMR (400 MHz CDCl3) (SI-Scheme 1)
d (ppm): 9.90 (s, 1H),
€
transfer mechanism within the system [12]. These findings
encouraged us to construct dendritic systems by attaching steroidal
nuclei to a porphyrin unit. Several synthetic routes can be used to
synthesize the porphyrinic dendrimers. The click reactions, namely
the copper (I)-catalysed 1,3-dipolar cycloaddition of azides and
terminal alkynes, produce in a regioselective manner the 1,4-
disubstituted 1,2,3-triazole products in high yields [13]. Since the
7.89e7.82 (m, 2H), 7.12e7.06 (m, 2H), 4.78 (d, J ¼ 2.42 Hz, 2H), 2.57
(t, J ¼ 2.40, 2.40 Hz, 1H).
2.3.2. Synthesis of 4-((3,5-bis(prop-2-yn-1-yloxy)benzyl)oxy)
benzaldehyde (3)
4-((3,5-bis(prop-2-yn-1-yloxy)benzyl)oxy)benzaldehyde
(3)
was obtained by a multistep Williamson etherification reaction.
First, 3,5-hydroxibenzylalcohol (5 g, 36 mmol) and propargyl bro-
mide (8 mL, 89 mmol) were reacted in dry acetone (50 mL) at 60 ꢀC
for 24 h. The crude product was purified by column chromatog-
raphy to yield (2) as a pale yellow solid. Secondly, an Appel reaction
was performed to give the corresponding alkyl bromide. This in-
termediate (1.68 g, 6.02 mmol) was further coupled in the presence
of 4-hydroxybenzaldehyde (0.74 g, 6.02 mmol), using K2CO3 (3.32 g,
2.4 mmol) as base in dry acetone (50 mL) at 60 ꢀC for 24 h (Fig. 1).
The crude product was purified by column chromatography using a
mixture of hexane: CHCl3 (3:7) as eluent to give the desired product
(3) as a pale yellow solid (1.41 g, 4.4 mmol). Yield: 73%.
1,2,3-triazole group has a significant performance as a
p-conju-
gated linker in intramolecular energy transfer processes [14,15], we
employed the click chemistry approach to link the cholic acid units
to the porphyrin core.
On the other hand, aggregation has been widely studied in
porphyrins, where H and J aggregates have been observed [16e23].
Particularly J-aggregates have a bright future in nanophotonics,
since they could operate in molecular plasmonic devices, where
they can feed nanostructures with absorbed light energy or serve as
self-assembled optical microcavities [23,24]. Many studies about
the formation of J-aggregates in porphyrins have been carried out
by different research groups focussing on applications such as pH
sensors, luminescence, electro and photoactivity [25e35].
In this work, we report for the first time novel dendritic por-
phyrins bearing cholic acid at the periphery and the study of their
optical and photophysical properties in terms of the meso-spacer
and the porphyrinic core. In addition, the aggregation phenomenon
was studied under different conditions in order to study the effects
of the following conditions on the self-assembly processes: polarity
of the solvent, presence of the triazole units, metallation of the
porphyrin and temperature.
1H NMR (400 MHz, CDCl3) (SI-Scheme 2)
d
(ppm) ¼ 2.69e2.64
(m, 2H), 4.81 (d, J ¼ 2.37 Hz, 4H), 5.23 (s, 2H), 6.72 (t, J ¼ 2.21,
2.21 Hz, 1H), 6.82 (d, J ¼ 2.17 Hz, 2H), 7.96 (d, J ¼ 8.71 Hz, 2H), 7.19
(d, J ¼ 8.69 Hz, 2H), 10.01 (s, 1H).
2.3.3. Synthesis of the porphyrin core
TPPh (2H) tetra-alkyne (4) was obtained using the Lindsey
method (Fig. 2) [36], which has been already reported in the liter-
ature. Pyrrole (0.495 mL, 7.1 mmol) and 4-(prop-2-1-yloxy)benz-
aldehyde (1) (1.13 g, 7.1 mmol) were dissolved in dry CH2Cl2
(31 mL); after 10 min of stirring BF3OEt2 (0.03835 mL, 0.71 mmol)
was added to the solution. Then, DDQ was added (0.709 g,
7.1 mmol) to the reaction mixture in order to achieve the oxidation
reaction. The crude product was purified by column
2. Experimental part
2.1. Equipment
1H and 13C NMR spectra of all compounds involved in the syn-
thesis were recorded on a Bruker Avance 400 MHz, operating at 400
and 100 MHz, for 1H and 13C, respectively, in CDCl4, MeOD4 or d6-
DMSO solution. The assignments of the signals are illustrated in the
Supporting Information (SI).
Absorbance spectra of the dendritic compounds were recorded
on a Cary Series UV vis NIR Spectrophotometer (Agilent Technol-
ogies) using quartz cells with a width of 1 cm, employing THF,
hexane and CHCl3 spectrometric grade as solvent. Fluorescence
spectra were recorded at room temperature on a Varian fluores-
cence spectrophotometer with a Xe-900 lamp exciting at 420 nm;
excitation and in both cases the emission slit widths were of 5 nm.
MALDI-TOF mass spectra were obtained using dithranol as matrix,
on a Bruker Daltonic Felx Analysis.
2.2. Reagents
All reagents employed in the synthesis were purchased from
SigmaeAldrich and used without further purification. The solvents
used in reactions were dried and purified by distillation and con-
ventional methods.
Fig. 1. Synthesis of 4-(prop-2-1-yloxy)benzaldehyde (1) and 4-((3,5-bis(prop-2-yn-1-
yloxy)benzyl)oxy)benzaldehyde (3).

112
E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
acetate in excess (Fig. 3). The progress of the reaction was moni-
tored by TLC until the reaction was completed; after that, the re-
action mixture was filtered and the product was employed without
further purification.
2.3.4.1. TPPh (Zn) tetra-alkyne (6). TPPh (2H) tetra-alkyne (3)
(0.76 g, 0.914 mmol) was dissolved in CHCl3 (20 mL) until the so-
lution was homogenous. Then, Zn (OAc)2 (1.67 g, 9.14 mmol) was
dissolved in MeOH (50 mL) and added to the reaction mixture,
which was stirred overnight, filtered, washed with water, and dried
with Na2SO4. The desired product was obtained as a purple solid
(735 mg, 0.822 mmol). Yield: 90%.
1H NMR (400 MHz, CDCl3) (SI-Scheme 7):
d
ppm ¼ 2.70 (t,
J ¼ 2.36, 2.36 Hz, 4H), 4.99 (d, J ¼ 2.33 Hz, 8H), 7.37 (d, J ¼ 8.35 Hz,
8H), 8.17e8.12 (m, 8H), 8.86 (s, 8H).
13C NMR (100 MHz, CDCl3)
d ppm 56.19, 75.82, 78.74,113,120.58,
Fig. 2. Synthesis of TPPh (2H) tetra-alkyne (4) and TPPh (2H) octa-alkyne (5).
131.93, 135.36, 136.09, 150.44, 157.31.
2.3.4.2. TPPh (Zn) octa-alkyne (7). This reaction was carried out
employing the same procedure described above, in this case using
TPPh (2H) octa-alkyne (5) (0.56 mg, 0.38 mmol) and Zn(OAc)2
(0.698 g, 3.8 mmol). The desired product was obtained as a purple
solid (525 mg 0.342 mmol). Yield: 90%.
chromatography using CH2Cl2 (100%) as eluent to give the product
(4) as purple crystals (90.1 mg, 0.108 mmol). Yield: 14%.
1H NMR (400 MHz, CDCl3) (SI-Scheme 3)
d
(ppm) ¼ ꢁ2.75 (s,
2H), 2.70 (dd, J ¼ 3.09, 1.66 Hz, 4H), 4.98 (d, J ¼ 2.38 Hz 8H), 7.36
(dd, J ¼ 9.02, 2.30 Hz 8H), 8.22e8.08 (m, 8H), 8.89 (s, 8H).
1H NMR (400 MHz, CDCl3) (SI-Scheme 8)
d
ppm ¼ 2.58 (t,
13C NMR (100 MHz, CDCl3) (SI-Scheme 4)
78.68, 113.13, 119.56, 135.49, 135.56, 157.46.
d
(ppm) ¼ 56.17, 75.84,
J ¼ 2.40, 2.40 Hz, 8H), 4.78 (d, J ¼ 2.40 Hz, 16H), 5.32 (s, 8H), 6.67 (t,
J ¼ 2.29, 2.29 Hz, 4H), 6.91 (d, J ¼ 2.27 Hz, 8H), 7.35 (d, J ¼ 8.64 Hz,
8H), 8.97 (s, 8H), 8.13 (d, J ¼ 8.59 Hz, 8H).
TPPh (2H) octa-alkyne (5) was obtained using the same proce-
dure described above (Fig. 2), employing 4-((3, 5-bis (prop-2-yn-1-
yloxy)benzyl)oxy)benzaldehyde (3) (500 mg, 1.56 mmol), pyrrole
(0.108 mL,1.56 mmol), BF3OEt2 (0.02 mL, 0.16 mmol), DDQ (354 mg,
1.56 mmol) and CH2Cl2 (16 mL). The product was obtained as a
purple solid (200 mg 0.136 mmol). Yield: 35%.
13C NMR (100 MHz, CDCl3)
d (ppm): 56.04, 75.79, 78.35, 101.89,
107.05, 113, 131.93, 135.42, 139.72, 150.45, 158.32, 158.98.
2.3.5. Cholic acid azidation
1H NMR (400 MHz, CDCl3) (SI-Scheme 5)
d
(ppm) ¼ 2.58 (t,
The azidation of cholic acid was achieved according to the
method reported by Pore et al. [37] and the synthetic sequence is
illustrated in Fig. 4.
J ¼ 2.39, 2.39 Hz, 8H), 4.78 (d, J ¼ 2.41 Hz, 16H), 5.32 (s, 8H), 6.68 (s,
1H), 6.91 (d, J ¼ 2.30 Hz, 4H), 7.35 (d, J ¼ 8.69 Hz, 8H), 8.12 (d,
J ¼ 8.70 Hz, 8H), 8.86 (s, 8H), ꢁ2.74 (s, 2H).
13C NMR (100 MHz, CDCl3) (SI-Scheme 6)
d
(ppm) ¼ 56.04,
2.3.5.1. Methyl
3
a,
7a,
12a-trihydroxy-5b-cholan-24-ate (8).
75.79, 78.35, 101.89, 107.05, 113, 131.93, 135.42, 139.72, 150.45,
158.32, 158.98.
Cholic acid (20 g, 48.9 mmol) was dissolved in methanol (100 mL)
and H2SO4 (3 mL) was added as catalyst; the reaction mixture was
heated at 80 ꢀC for 3 h. Then, the solvent was removed under
vacuum and the solid was extracted using ethyl acetate and water
(1:1). The obtained product was used in the next step without
further purification.
2.3.4. Metallation of the porphyrin core
The metallation of the porphyrin core was carried out by dis-
solving the porphyrin in chloroform with further addition of zinc
Fig. 3. Synthesis of TPPh (Zn) tetra-alkyne (6) and TPPh (Zn) octa-alkyne (7).

E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
113
Fig. 4. Synthesis of 3a, 7a, 12a-Trihydroxy 24-azido-5b-cholane (11).
2.3.5.2. 3
Methyl
a
, 7
,
a
, 12
a
-Tetrahydroxy-5
12a-trihydroxy-5
b
-cholane (9). For the next step
-cholan-24-ate (8) (23 g,
0.2236 mmol) was added to a mixture of dry THF (2 mL) and Et3N
(2 mL) to get a homogeneous solution. Then 3 ,7 ,12 -Trihydroxy
24-azido-5 -cholane (11) (0.563 g, 1.34 mmol) and a catalytic
3
a
7
a,
b
a
a
a
54.5 mmol) was dissolved in THF at 0 ꢀC. Afterwards, LiAlH4
(10.34 g, 272.5 mmol) was added slowly and the mixture was
stirred overnight. A mixture of water and ethyl acetate (4:2) was
added slowly in order to quench the reaction and the mixture was
stirred for 2 more hours. Then, it was filtered under vacuum and the
product was purified by extraction using water, ethyl acetate and
brine. The organic phase was concentrated at reduced pressure and
the desired product was obtained as a white solid (19.9 g,
50.4 mmol). Yield: 92%.
b
amount of CuBr(PPh3)3 were added. The resulting reaction mixture
was heated at 60 ꢀC for 3 days; then the reaction was quenched. The
crude product was obtained as a dark purple solid, which was
washed with methanol, acetone, ethyl acetate, chloroform and
dichloromethane. Finally the product (Fig. 5) was purified by col-
umn chromatography using CH2Cl2:MeOH (97:3) as eluent and
concentrated at reduced pressure to give a purple solid (0.42 g,
0.16 mmol) Yield: 73%.
1H NMR (400 MHz, DMSO-d6)
3.65e3.58 (m, 1H), 3.83e3.76 (m, 1H), 4.31 (t, J ¼ 4.76, 4.76 Hz, 2H),
4.09 (d, J ¼ 3.61 Hz, 1H), 4.00 (d, J ¼ 3.42 Hz, 1H), 0.9 (d J ¼ 6.5 Hz
3H) 0.60 (s, 3H), 0.81 (s, 3H).
d
ppm 3.24e3.13 (m, 1H),
1H NMR (400 MHz, DMSO-d6) (SI-Scheme 10)
d
ppm ¼ 0.62 (s,
12H), 0.84 (s, 12H), 0.98e0.93 (m, 12H), 3.63e3.57 (m, 4H),
3.71e3.65 (m, 4H), 3.87e3.80 (m, 4H), 4.20e4.16 (m, 4H, OH),
4.29e4.25 (m, 4H, OH), 4.34e4.29 (m, 4H, OH), 5.48e5.37 (m, 8H),
7.49e7.42 (m, 8H), 8.10e8.05 (m, 8H), 8.49e8.46 (m, 4H), 8.79 (s,
8H).
2.3.5.3. 3
a,
7
a,
12
a-Trihydroxy 24-mesyloxy-5
b-cholane (10).
13C NMR (100 MHz, DMSO-d6) (SI-Scheme 11)
d (ppm): 149.43,
3
a
, 7 , 12
a
a
-Tetrahydroxy-5b
-cholane (9) (3 g, 7.6 mmol) was dis-
solved in pyridine and the solution was placed in an ice bath at 0 ꢀC.
Mesylchloride (0.6 mL, 7.6 mmol) was then slowly added and the
reaction mixture was stirred for 30 min; then it was quenched with
water. The product was extracted using water, ethyl acetate and
brine. After that, the organic phase was concentrated under vac-
uum and the crude product was purified by column chromatog-
raphy using ethyl acetate and hexanes (7:3). The desired product
(10) was obtained as a white powder (500 mg, 1.05 mmol). Yield:
14%.
142.27, 135.12, 131.45, 124.06, 119.83, 112.86, 79.10, 79.08, 71.02,
70.94, 66.18, 66.04, 61.43, 61.34, 61.29, 57.89, 48.52, 46.26, 45.69,
41.33, 36.85, 35.39, 34.01, 32.08, 31.8, 30.61, 29.22, 27.33, 26.11,
22.97, 17.36, 12.3.
MALDI-TOF-MS
152H200N16O16Zn: 2572.69; found 2572.47 [MþH]
(SI-Scheme
12):
m/z:
calcd
for
þ
C
.
2.3.6.2. TPPh (Zn) octa-CA (13). TPPh (Zn) octa-alkyne (8) (100 mg,
0.0423 mmol) was dissolved in a mixture of dry THF (2 mL) and
Et3N (2 mL). Then, 3a, 7a, 12a-Trihydroxy 24-azido-5b-cholane (11)
1H NMR (400 MHz, CDCl3)
d (ppm): 0.71 (s, 3H), 0.91 (s, 3H),
1.02e0.97 (m, 3H), 2.99 (d, J ¼ 0.88 Hz, 3H), 3.67e3.58 (m, 2H),
(0.1773 g, 0.423 mmol) and a catalytic amount of CuBr(PPh3)3 were
added. The reaction mixture was heated at 60 ꢀC for 5 days (Fig. 6).
The crude product was purified by column chromatography using
CH2Cl2:MeOH (97:3). Finally, the desired product was obtained as a
purple solid (155 mg, 0.0317 mmol). Yield: 75%.
3.90e3.83 (m, 1H), 4.05e3.98 (m, 1H), 4.60e4.46 (m, 1H).
2.3.5.4. 3
a, 7a
, 12
a-Trihydroxy 24-azido-5b-cholane (11). 3a, 7a,
12 -Trihydroxy 24-mesyloxy-5
a
b
-cholane (10) (1 g, 2.38 mmol) was
1H NMR (400 MHz DMSO-d6) (SI-Scheme 13)
d
ppm ¼ 0.56 (s,
dissolved in dry DMF. Then, sodium azide (0.873 g, 13.4 mmol) was
added and the reaction mixture was heated at 80 ꢀC for 24 h. The
product was isolated by extraction using water, ethyl acetate and
brine. Afterwards it was purified by column chromatography using
ethyl acetate and hexanes (6:4). The desired product (11) was ob-
tained as a white powder (598 mg, 1.428 mmol). Yield: 60%.
24H), 0.77 (s, 24H), 0.94e0.91 (m, 24H), 3.65e3.60 (m, 8H),
3.83e3.77 (m, 8H), 4.17e4.10 (m, 8H), 4.24e4.19 (m, 8H, OH),
4.37e4.26 (m, 8H, OH), 4.70e4.64 (m, 8H, OH), 5.25e5.19 (m, 16H),
5.35e5.31 (m, 8H), 6.83e6.80 (m, 4H), 6.97e6.94 (m, 8H), 7.47e7.41
(m, 8H), 8.12e8.07 (m, 8H), 8.38e8.35 (m, 8H), 8.83e8.79 (m, 8H).
13C NMR (100 MHz, DMSO-d6) (SI-Scheme 14)
d (ppm):149.42,
1H NMR (400 MHz, CDCl3) (SI-Scheme 9)
0.93 (s, 3H), 1.0 (d, 3H), 3.62 (m, 2H), 3.86 (m, 1H), 3.9 (m, 1H), 4.01
(m, 1H).
d
ppm ¼ 0.70 (s, 3H),
142.05, 135.23, 131.72, 130.99, 124.01, 112.85, 107.08, 106.96, 70.98,
66.12, 61.39, 60.33, 56.27, 46.54, 45.32, 41.29, 36.82, 34.43, 31.83, 29,
26.16, 26.02, 24.14, 22.92, 22.64, 17.39, 12.36.
MALDI-TOF-MS
(SI-Scheme
15):
m/z:
calcd
for
2.3.6. Synthesis of modified porphyrins
After having obtained TPPh (Zn) tetra-alkyne (7), TPPh (Zn) octa-
alkyne (8) and the 3a, 7a, 12a-Trihydroxy 24-azido-5b-cholane (11)
C
288H396N28O36Zn: 4886.93; found 4890.72 [MþH]þ.
2.3.7. Demetallation of TPPh (Zn) tetra-CA (12) and TPPh (Zn) octa-
CA (13)
we carried out the corresponding coupling reaction to obtain the
final products: TPPh (Zn) tetra-CA (12) and TPPh (Zn) octa-CA (13).
2.3.7.1. TPPh (2H) tetra-CA (14). TPPh (Zn) tetra-CA (12) (61 mg,
2.3.6.1. TPPh (Zn) tetra-CA (12). TPPh (Zn) tetra-alkyne (7) (200 mg,
0.0237 mmol) was dissolved in THF and a few drops of concentrated

114
E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
Fig. 5. Synthesis of TPPh (Zn) tetra-CA (12).
Fig. 6. Synthesis of TPPh (Zn) octa-CA (13).
H3PO4 were added to the solution. The reaction mixture was stirred
for 24 h (Fig. 7). Once the reaction was completed the product was
isolated by biphasic extraction using THF and water; the extractions
were repeated until the solution had a value of pH ¼ 6 and the
colour changed from green to purple. The organic phase was dried
with Na2SO4 and concentrated under vacuum. The desired product
was obtained as a purple solid (53.57 mg, 0.0213 mmol). Yield: 90%.
7.53e7.46 (m, 8H), 8.16e8.10 (m, 8H), 8.50e8.47 (m, 4H), 8.8 (s, 8H).
MALDI-TOF-MS (SI-Scheme 17): m/z: calcd for C152H202N16O16
:
2507.55; found 2510.86 [MþH]þ.
2.3.7.2. TPPh (2H) octa-CA (15). TPPh (Zn) octa-CA (13) (50 mg,
0.0102 mmol) was treated under the same reaction conditions
described above, using the same demetallation and purification
methods (Fig. 8). The product was obtained as a purple solid
(44.3 mg, 0.00919 mmol). Yield: 90%.
1H NMR (400 MHz, DMSO-d6) (SI-Scheme 16)
d
ppm ꢁ2.86 (m, 2H),
0.60 (m, 12H), 0.83 (m, 12H), 0.97e0.92 (m, 12H), 3.70e3.64 (m,
4H), 3.78e3.74 (m, 4H), 3.86e3.82 (m, 4H), 4.21e4.16 (m, 4H, OH),
4.29e4.25 (m, 4H, OH), 4.36e4.31 (m, 4H, OH), 5.47e5.41 (m, 8H),
1H NMR (400 MHz, DMSO-d6) (SI-Scheme 18)
(m, 2H) 0.49e0.45 (m, 24 H), 0.71e0.66 (m, 24H), 0.92e0.86 (m,
d
(ppm) ¼ ꢁ2.80
Fig. 7. Synthesis of TPPh (2H) tetra-CA (14).

E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
115
Fig. 8. Synthesis of TPPh (2H) octa-CA (15).
24H), 3.66e3.57 (m, 8H), 3.56e3.49 (m, 8H), 3.75e3.68 (m, 8H),
observed.
4.12e4.06 (m, 8H, OH), 4.19e4.12 (m, 8H, OH), 4.33e4.27 (m, 8H,
OH), 5.23e5.19 (m, 16H), 5.35e5.32 (m, 8H), 6.80e6.78 (m, 4H),
6.96e6.95 (m, 8H), 7.47e7.44 (m, 8H), 8.14e8.11 (m, 8H), 8.35e8.33
(m, 8H), 8.86e8.82 (m, 8H).
For porphyrin TPPh (2H) octa-alkyne (4) the structure was also
confirmed by NMR spectroscopy. We observe a singlet at 8.86 ppm
due the b-pyrrole protons, as well as a series of signals located at
8.13e8.10, 7.36e7.33, 6.91e6.90 and 6.68e6.66 ppm corresponding
to the phenyl protons of the construct. A singlet at 5.31 ppm due to
CH2eO protons, followed by a doublet at 4.78e4.77 ppm belonging
to the CH2eC^C protons, a triplet at 2.58 ppm corresponding to the
C^CeH protons and a singlet at ꢁ2.75 due to the porphyrin inner
protons are also seen.
MALDI-TOF-MS (SI-Scheme 19): m/z: calcd for C288H398N28O36
:
4825.02; found 4849.67 [M þ H]þ.
3. Results and discussion
The synthesis of four novel dendritic compounds bearing a
porphyrin core and four or eight cholic acid units as peripheral
groups was carried out successfully by the use of click chemistry.
This approach consists on a series of azide-alkyne couplings, which
allows the preparation of highly functionalized dendritic molecules
under mild conditions. Furthermore, the demetallation was ach-
ieved from the corresponding metallated porphyrins in order to see
the influence of the metal on the optical and photophysical
properties.
3.2. Metallation of the dendronized porphyrins
The metallation of the porphyrin core was carried out in the
presence of Zn (OAc)2 before the coupling reaction to avoid any
complexation of the porphyrin core with copper derivatives,
thereby obtaining the corresponding Zn-metallated compound
[38]. In both compounds, TPPh (Zn) tetra-alkyne (5) and TPPh (Zn)
octa-alkyne (6), the insertion of the metal was confirmed by 1H
NMR spectroscopy due to the absence of the singlet arising from
the inner protons of the free base porphyrin, which usually appear
at ꢁ2.75 ppm.
3.1. Synthesis and characterization of the dendronized porphyrins
Both dendronized porphyrins were obtained via click chemistry
using azide-alkyne couplings. For this aim, we employed mild
conditions that allow us to get a high functionalization of the
porphyrin core, using a small amount of solvent with a simple
purification.
The dendronized porhyrins were synthesized as shown in
Figs. 5e8. Firstly, the cholic acid unit was functionalized with multi-
step reactions to give a cholic acid derivative bearing a terminal
azide group (11) (Fig. 4). This intermediate was further coupled in
the presence of a functionalized porphyrin containing 4 and 8
terminal alkyne groups to give 12 and 13 (Figs. 5 and 6). The pre-
cursor porphyrins (4 and 5) were obtained by reacting 4 equiv of
pyrrol in the presence of 4 equiv of the appropriate benzaldehyde
derivative (Fig. 2). All the intermediates and final compounds
prepared in this work were characterized by 1H and 13C NMR
spectroscopy. The synthetic methods and the assignment of the
NMR signals are described in detail in the Experimental Section.
The 1H NMR spectrum of 4-(prop-2-1-yloxy)benzaldehyde (1)
shows the signal of the terminal alkyne proton at 2.57 ppm.
However, for 4-((3,5-bis(prop-2-yn-1-yloxy)benzyl)oxy)benzalde-
hyde (2) the terminal alkyne proton signal appears at 2.69 ppm,
which confirms the structure of these intermediates.
In the 1H NMR spectra of TPPh (Zn) tetra-CA (12) and TPPh (Zn)
octa CA (13), two spectral changes reveal the success in achieving
the azide-alkyne coupling. The signal at 2.60 ppm due to the ^CeH
proton disappeared, whereas a new signal at 8.40 ppm due to the
triazole protons appeared, thereby proving that the expected
coupling occurred.
3.3. Demetallation of the dendronized porphyrins
Finally, TPPh (Zn) tetra-CA (12) and TPPh (Zn) octa CA (13) were
demetallated (Figs. 7 and 8) to obtain the free-base derivatives TPPh
(2H) tetra-CA (14) and TPPh (2H) octa-CA (15), respectively. The
demetallation is confirmed by 1H NMR spectroscopy by the
appearance of the signal at ꢁ2.80 ppm (inner protons) and the
remaining signal at 8.40 ppm of the triazole protons.
In the case of the porphyrin TPPh (2H) tetra-alkyne (3) the NMR
spectrum shows a singlet at 8.86 ppm due to the b-pyrrole protons,
followed by two doublets at 8.15e8.13 and 7.37e7.34 ppm
belonging to the orto and meta phenyl protons. In addition, a
doublet at 4.98e4.97 ppm due to methylene groups, a triplet at
2.69 ppm corresponding to the terminal alkyne proton and a singlet
at ꢁ2.75 ppm related to the porphyrin inner protons are also
3.4. Optical properties of the dendronized porphyrins
The absorption spectra of the free base porphyrins TPPh(2H)

116
E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
tetra-CA and TPPh(2H) octa-CA exhibited an intense absorption
band (Soret band) at 421 nm, due to S0 / S2 transition, followed by
a series of low intensity bands (Q bands) at 517, 553, 594 and
651 nm (see Table 1) arising from the S0/S1 transition. On the
other hand, the UVevis spectra of branched metallated porphyrins,
TPPh(Zn) tetra-alkyne, TPPh(Zn) octa-alkyne, TPPh(Zn) tetra-CA and
TPPh(Zn) octa-CA, showed a Soret band at 426 nm, corresponding to
the S0/S2 transition, followed by two Q bands at 559 and 599 nm,
due to the S0/S1 transition. After metallation the absorption bands
of the porphyrins showed a red shift compared to the non-
metallated porphyrins. Moreover, Zn-metallated porphyrins
exhibit two Q bands instead of four, because of their higher
symmetry.
resulted to be broader and the Q bands exhibit also a red shift of
3 nm compared to porphyrin (13). According to these results, it is
possible to remark the influence of the triazole units in the self-
assembly of the branched porphyrins in aqueous media. The
presence of this moiety makes possible the formation of J-aggre-
gates because of the possible interactions between triazole units
with Zinc (II).
3.7. Effect of the metallation
The metallation of the branched porphyrins plays an important
role in the formation of aggregates. To obtain a deeper insight, we
have studied the metallated porphyrins (TPPh (Zn) tetra-CA (12) and
TPPh (Zn) octa-CA (13)) as well as their free base analogues (TPPh
(2H) tetra-CA (14) and TPPh (2H) octa-CA (15)) by absorption spec-
troscopy (Fig. 11).
It is well known that the interaction of zinc (II)-porphyrins with
pyridine or imidazole tends to give a good association without
spoiling the photoexcited-state dynamics of porphyrins [39,40].
The Soret band is the most affected, showing a broadening and a
red shift due to the electron-withdrawing effect of the metal ion. In
the Zn-metallated porphyrins, the Soret band also changes in shape
due to the self-assembly process (aggregation) promoted by the
triazole-zinc (II) interactions. As soon as we remove the Zinc (II)
ions these interactions disappear and the self-assembly process do
not occur, which can be detected by the shape and wavelength of
the Soret band.
In the emission spectra of the free base porphyrins, two bands
are observed at 650 and 721 nm due to the S1 / S0 transition (see
Table 1). By contrast, in the corresponding metallated porphyrins
these bands appear at 605 and 650 nm, thereby showing a signif-
icant blue shift.
3.5. Aggregation in function of the polarity of the solvent
With the aim to study the effect of the polarity of the solvent on
the self-assembly behaviour, we prepared 2 mM solutions of TPPh
(Zn) tetra-CA (12) and TPPh (Zn) octa-CA (13) using THF as starting
solvent, and the percentage of water varied from 0 to 70%; the
aggregation was studied by monitoring the changes in the UVevis
spectra, the porphyrin concentration was kept in 2 mM (Fig. 9).
As soon as the polarity of the solvent increases, both metallated
porphyrins, TPPh (Zn) tetra-CA (12) and TPPh (Zn) octa-CA (13) start
to form J-aggregates, which is confirmed by a broadening of the
Soret band of TPPh (Zn) tetra-CA (12). In the case of TPPh (Zn) octa-
CA (13), a red shift of the Soret band from 427 to 433 nm is observed
in both compounds. Moreover, the Q bands exhibit also a significant
red shift from 558 to 664 nm.
3.8. Effect of the temperature
The temperature is one of the main factors able to modify the
self-assembly process, so that we decided to perform some ex-
periments in order to monitor the formation of aggregates as a
function of the temperature and to study thermal stability of the
metallated porphyrins (Fig. 12).
It is worth noticing that in the absorbance spectra of TPPh (Zn)
tetra-CA (12) and TPPh (Zn) octa-CA (13), as soon as we increase the
temperature, the Soret band exhibits significant changes in shape
and shift. Enhancing the temperature provokes a disappearance of
the Zn-porphyrin-triazole interactions, thereby causing a dissoci-
ation of the J-aggregates. This can be observed by the changes in
shape and shift of the Soret band. In the case of TPPh (Zn) tetra-CA
(12) once the temperature increased the shoulder of the Soret band
vanished and the Soret band suffered a slight blue shift from 429 to
427 nm at 55 ꢀC. On the contrary, upon the heating in the UVevis
spectrum of TPPh (Zn) octa-CA (13) the Soret band became narrower
and exhibited a blue shift from 439 to 435 nm.
3.6. Influence of triazole moieties
Similarly, to study how the presence of triazole units may affect
the self-assembly behaviour of the metallated porphyrins, we
prepared 2 mM solutions of TPPh (Zn) tetra-alkyne (5), TPPh (Zn)
octa-alkyne (6), TPPh (Zn) tetra-CA (12), and TPPh (Zn) octa-CA (13)
under the conditions mentioned above, increasing gradually the
quantity of water in order to see whether the J-aggregates are
formed (Fig. 10).
In TPPh (Zn) tetra-CA (12) and TPPh (Zn) octa-CA (13), the Soret
band exhibits a red shift. In the case of TPPh (Zn) tetra-CA (12) the
slight red is about 2 nm; the main difference is the spectral change
in the Soret band shape, since in TPPh (Zn) tetra-alkyne (6) this band
is sharp and well defined, whereas in porphyrin (12) the Soret band
is broader, showing a shoulder which indicates the presence of J-
aggregates [16]; in addition the Q bands show a red shift of 5 nm.
On the other hand, TPPh (Zn) octa-CA (13) shows a red shift of 3 nm
in the Soret band, compared to TPPh (Zn) octa-alkyne (7). This band
3.9. Effect of the aggregates on the emission
The comparison of the emission spectra of compounds TPPh(Zn)
tetra-alkyne (6), TPPh(Zn) tetra-CA (12) (Fig. 13), TPPh(Zn) octa-
alkyne (7) and TPPh(Zn) octa-CA (13) (Fig. 14) confirms the
Table 1
Optical properties of the free base and metallated porphyrins in THF.
Compound
Absorption
(nm)
ε
Cut off
(nm)
Emission
l (nm)
Cut off
(nm)
l
(Mꢁ1 cmꢁ1 at)
TPPh (Zn) tetra-alkyne
TPPh (Zn) octa-alkyne
TPPh (Zn) tetra-CA
TPPh (Zn) octa-CA
TPPh (2H) tetra-CA
TPPh (2H) octa-CA
426, 559, 598
426, 557, 599
426, 558, 599
427, 557, 598
421, 517, 553, 594, 651
421, 519, 554, 594, 651
274,069
474,232
550,220
306,029
342,026
516,988
650
650
650
650
700
700
605, 658
614, 656
608, 659
615, 655
657, 721
654, 719
750
750
750
750
800
800

E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
117
0.20
TPPh(Zn) octa-CA
TPPh(Zn) tetra-CA
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0%
0%
Water percentage
Water percentage
0.010
0.008
0.006
0.004
0.002
0.000
-0.002
0.010
0.008
0.006
0.004
0.002
0.000
70%
70%
500
520
540
560
580
600
620
640
660
500
520
540
560
580
600
620
640
660
500
600
400
500
600
Wavelength (nm)
Wavelength (nm)
Fig. 9. UVevis spectra of the TPPh (Zn) tetra-CA and TPPh (Zn) octa-CA recorded in different THF: water mixtures: (100:0; 90:10; 80:20; 70:30; 60:40; 50:50; 40:60 and 30:70) at
room temperature (conc ¼ 2
mM).
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0.10
0.08
0.06
0.04
0.02
0.00
TPPh (Zn) octa-CA
TPPh (Zn) tetra-CA
TPPh (Zn) octa-alkyne
TPPh (Zn) tetra-alkyne
400
500
600
700
400
500
600
700
Wavelength (nm)
Wavelength (nm)
Fig. 10. Triazole moieties and J-aggregate assembly dependence in THF: water (30:70) media at room temperature (conc ¼ 2
mM).
0.10
TPPh(Zn) tetra-CA
TPPh(2H) tetra-CA
TPPh(Zn) octa-CA
TPPh(2H) octa-CA
0.06
0.05
0.04
0.03
0.02
0.01
0.08
0.06
0.04
0.02
400
500
600
400
500
600
Wavelength (nm)
Wavelength (nm)
Fig. 11. Influence of the metallation on the formation of J-aggregates recorded in THF: water (30:70) media at room temperature (conc ¼ 2
mM).
formation of porphyrin aggregates in THF:water and THF: hexane
solutions [41].
As we can see, TPPh(Zn) tetra-alkyne (Fig. 13 right) shows the
typical emission spectrum of a porphyrin in THF (black line).
However, as soon as we change the polarity of the media, using
mixtures THF:water 30:70 (red line), THF:Hexane 30:70 (blue line)
and THF:chloroform 30:70 (magenta line) we can observe signifi-
cant changes in the intensity of the emission bands, due to the

118
E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
25
30
35
40
45
50
55
TPPh (Zn) octa-CA
TPPh (Zn) tetra-CA
25 C
30 C
35 C
40 C
45 C
50 C
55 C
0.09
0.06
0.03
0.06
0.03
0.00
420
440
460
420
440
460
Wavelength (nm)
Wavelength (nm)
Fig. 12. Temperature dependence in the J-aggregate assembly recorded in THF:water (30:70) at room temperature (conc ¼ 2
mM).
40
THF
H2O
THF
H2O
TPPh(Zn) tetra-alkyne
TPPh(Zn) tetra-CA
30
25
20
15
10
5
35
30
25
20
15
10
5
Hexane
CHCl3
Hexane
CHCl3
0
0
550
600
650
700
750
800
550
600
650
700
750
800
Wavelength (nm)
Wavelength (nm)
Fig. 13. Emission spectra of TPPh(Zn) tetra-CA (left) and TPPh(Zn) tetra-alkyne (right) in THF:water 30:70 (red line), THF:hexanes 30:70 (blue line), THF:CHCl3 30:70 (magenta line)
and THF (black line) at room temperature (conc ¼ 2
mM). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
35
TPPh(Zn) octa-CA
TPPh(Zn) octa-alkyne
THF
H2O
THF
H2O
50
40
30
20
10
0
30
25
20
15
10
5
Hexane
CHCl3
Hexane
CHCl3
0
550
600
650
700
750
800
550
600
650
700
750
800
Wavelength (nm)
Wavelength (nm)
Fig. 14. Emission spectra of TPPh(Zn) octa-CA (left) and TPPh(Zn) octa-alkyne (right) in THF:water 30:70 (red line), THF:hexanes 30:70 (blue line), THF:CHCl3 30:70 (magenta line)
and THF (black line) at room temperature (conc ¼ 2 M). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
m
formation of aggregates, which are less emissive.
When we performed the same experiments with TPPh(Zn)
tetra-CA (Fig. 13 left) this compound exhibited a typical behaviour
in THF, however, the emission spectra changed drastically in shape
and intensity in THF:water 30:70 (red line), THF:Hexane 30:70
(blue line) and THF:chloroform 30:70 (magenta line). It is worth to

E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
119
ꢀ
[8] Zaragoza-Galan G, Fowler MA, Duhamel J, Rein R, Solladie N, Rivera E. Syn-
thesis and characterization of novel pyrene-dendronized porphyrins exhib-
iting efficient fluorescence resonance energy transfer: optical and
photophysical properties. Langmuir 2012;28:11195e205. http://dx.doi.org/
10.1021/Ia301284v.
point out that in THF:water 30:70 and THF:hexane 30:70 this
compound showed a significant quenching in the emission bands,
arising from the formation of the aggregates. A similar behaviour
has been reported for other similar porphyrinic compounds, whose
aggregates showed poor emission intensity [41].
The emission spectra of compounds TPPh(Zn) octa-CA and
TPPh(Zn) octa-alkyne are shown in Fig. 14, left and right, respec-
tively. A similar behaviour has been also observed in these systems,
which confirmed the formation of aggregates as in the previous
case.
ꢀ
[9] Zaragoza-Galan G, Fowler M, Rein R, Solladie N, Duhamel J, Rivera E. Fluo-
rescence resonance energy transfer in partially and fully labeled pyrene
dendronized porphyrins studied with model free analysis. J Phys Chem C
2014;118:8280e94. http://dx.doi.org/10.1021/jp501445n.
ꢀ
[10] Caicedo C, Zaragoza-Galan G, Crusats J. Design of novel luminescent por-
phyrins bearing donoreacceptor groups. J. Porphyr Phthalocyanines 2014;18:
209e20. http://dx.doi.org/10.1142/S1088424613501083.
[11] Davis AP. Anion binding and transport by steroid-based receptors. Coord
Chem Rev 2006;250:2939e51. http://dx.doi.org/10.1016/j.ccr.2006.05.008.
[12] Vollmer MS, Effenberger F, Stu T, Hartschuh A, Port H, Wolf HC. Steroid-
bridged anthryloligothienylporphyrins : synthesis and study on the intra-
molecular energy transfer. J Org Chem 1998;63:5080e7. http://dx.doi.org/
10.1021/jo980251e.
[13] Kolb HC, Finn MG, Sharpless KB. Click chemistry: diverse chemical function
from a few good reactions. Angew Chem Int Ed 2001;40:2004e21. http://
dx.doi.org/10.1002/1521-3773(20010601)40:11<2004::AID-
4. Conclusion
A new series of dendronized porphyrins containing cholic acid
units were synthesized and characterized. The absorption and
emission spectra show the characteristic bands of the porphyrin
core which are not significantly affected by the presence of the
cholic acid units. These compounds exhibit the typical Soret ab-
ANIE2004>3.0.CO;2e5.
[14] Leonardi MJ, Topka MR, Dinolfo PH. Efficient forster resonance energy transfer
€
in
1,2,3-triazole
linked
bodipy-zn(ii)
meso-tetraphenylporphyrin
sorption of the porphyrin at ca.
bands between 500 and 700 nm. After metallation, the Soret band
red-shifts to ca.
¼ 421 nm and only two Q bands are observed. The
free base porphyrins show emission at ca.
¼ 657 and 721 nm
whereas after metallation these bands are blue-shifted to ca.
¼ 605 and 658 nm. The aggregation phenomenon was studied as
l
¼ 421 nm followed by four Q
donoreacceptor arrays. Inorg Chem 2012;51:13114e22. http://dx.doi.org/
10.1021/ic301170a.
[15] Nguyen NT, Hofkens J, Scheblykin IG, Kruk M, Dehaen W. Click reaction
synthesis and photophysical studies of dendritic metalloporphyrins. Eur J Org
Chem 2014;8:1766e77. http://dx.doi.org/10.1002/ejoc.201301158.
[16] Scheibe VII G. Fachgebiet photochemie und photographische chemie. Angew
Chem 1936;49:562e4. http://dx.doi.org/10.1002/ange.19360493110.
[17] Scheibe G. Herstellung von Futterhefen aus Sulfitablaugen. Angew Chem
1937;50:51. http://dx.doi.org/10.1002/ange.19370500113.
[18] Jelley EE. Molecular, nematic and crystal states of I: I-diethyldcyanine chlo-
ride. Nature 1937;139:631e2. http://dx.doi.org/10.1038/139631b0.
[19] Verma S, Ghosh A, Das A, Ghosh NH. Ultrafast exciton dynamics of j- and h-
aggregtes of the porphyrin-catechol in aqueous solution. J Phys Chem B
2010;114:8327e34. http://dx.doi.org/10.1021/jp101643c.
[20] Schenning APHJ, Meijer EW. Supramolecular electronics; nanowires from self-
assembled p-conjugated systems. Chem Commun 2005:3245e58. http://
dx.doi.org/10.1039/B501804H.
[21] Konigstein C, Bauer R. Photoinduced hydrogen production in dilute solutions
and organized assemblies. Int J Hydrogen Energy 1993;18:735e41. http://
dx.doi.org/10.1016/0360-3199(93)90152-Z.
l
l
l
a function of factors such as the polarity of the solvent, tempera-
ture, metallation and presence of the triazole rings. Increasing the
polarity of the solvent gives rise to the formation of J-aggregates.
On the other hand the metallated porphyrins containing triazole
units favour the formation of intramolecular J-aggregates due to
the triazole-zinc (II) interactions. Enhancing the temperature pro-
vokes a disappearance of the Zn-porphyrin-triazole interactions,
thereby causing a dissociation of the J-aggregates.
Acknowledgements
[22] Liu S, Wang MW, Briseno LA, Mannsfeld BCS, Bao Z. Controlled deposition of
crystalline organic semiconductors for field-effect-transistor applications. Adv
Mater 2009;21:1217e32. http://dx.doi.org/10.1002/adma.200802202.
[23] Salomon A, Genet C, Ebbensen WT. Molecule-light complex: dynamic of
hybrid molecule-surface plasmon states. Angew Chem Int Ed 2009;121:
8904e7. http://dx.doi.org/10.1002/ange.200903191.
ꢀ
~
ꢀ
We thank María de los Angeles Pena Gonzalez, Elizabeth Huerta
Salazar, Gerardo Cedillo, Louiza Mahrouche and Marie-Christine
Tang for their assistance in the characterization of all the com-
pounds. We are also grateful to CONACYT (Projects 128788 and
253155), PAPIIT (Project IN-100316) and NSERC Canada. EAO thanks
Posgrado en Ciencias Químicas UNAM, and CONACYT for scholar-
ship and Ph.D. Grant (223409).
[24] Vacha M, Furuki M, Pu SL, Hashizume K, Tani T. Individual J-aggregate
nanostructures as self-assembled organic microcavities.
J Phys Chem B
2001;105:12226e9. http://dx.doi.org/10.1021/jp011360r.
[25] Zhao Y, Thorkelsson K, Mastroianni JA, Schilling T, Luther MJ, Rancatore JB,
et al. Small-molecule-directed nanoparticle assembly towards stimuli-
responsive nanocomposites. Nat Mater 2009;8:979e85. http://dx.doi.org/
10.1038/nmat2565.
ꢀ
[26] D'Urso A, Fragala ME, Purrello R. From self-assembly to noncovalent synthesis
Appendix A. Supplementary data
of programable porphyrins arrays in aqueous solution. Chem Commun
2012;48:8165e76. http://dx.doi.org/10.1039/c2cc31856c.
[27] Egawa Y, Hayashida R, Anazai J. pH-induced interconversion between J-ag-
gregates and H-aggregates of 5, 10, 15, 20-tetrakis (4-sulfonatophenyl)
porphyrin in polyelectrolyte multilayer films. Langmuir 2007;23:13146e50.
http://dx.doi.org/10.1021/Ia701957b.
[28] Arai Y, Segawa H. Cl- complexation induced H- and J-aggregation of meso-
tetrakis (4-sulfonatothienyl) porphyrin diacid in aqueous solution. J Phys
Chem B 2011;115:7773e80. http://dx.doi.org/10.1021/jp2018428.
[29] Shirakawa M, Kawano S, Fujita N, Sada K, Shinkai S. Hydrogen-bond-assisted
control of h versus j aggregation mode of porphyrins stacks in an organogel
system. J Org Chem 2003;68:5037e44. http://dx.doi.org/10.1021/jo0341822.
[30] Bhosale VS, Kalyankar BM, Nalage VS, Lalander HC, Bhosale VS, Langford SJ,
et al. pH dependent molecular self-assembly of octaphosphonate porphyrin of
nanoscale dimensions: nanosphere and nanorod aggregates. Int J Mol Sci
2011;12:1464e73. http://dx.doi.org/10.3390/ijms12031464.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.dyepig.2016.04.047.
References
[1] Senge BMO, Fazekas M, Notaras EGA, Blau WJ, Zawadzka M, Locos OB.
Nonlinear optical properties of porphyrins. Adv Mater 2007;19:2737e74.
http://dx.doi.org/10.1002/adma.200601850.
[2] Suijkerbuijk BM, Gebbink RJ. Merging porphyrins with organometallics :
synthesis and applications. Angew Chem Int Ed Engl 2008;47:7396e421.
http://dx.doi.org/10.1002/anie.200703362.
[3] Anderson HL. Building molecular wires from the colours of life : conjugated
porphyrin oligomers. Chem Commun 1999:2323e30. http://dx.doi.org/
10.1039/A904209A.
[31] Okada S, Segawa H. Substituent-control exciton in J-aggregates of protonated
ꢀ
water-insoluble porphyrins.
dx.doi.org/10.1021/ja017768j.
J Am Chem Soc 2003;125:2792e6. http://
€
[4] Auwarter W, Ecija D, Klappenberger F, Barth JV. Porphyrins at interfaces. Nat
Chem 2015;7:105e20. http://dx.doi.org/10.1038/nchem.2159.
[5] Gottfried JM. Surface chemistry of porphyrins and phthalocyanines. Surf Sci
Rep 2015;70:259e379. http://dx.doi.org/10.1016/j.surfrep.2015.04.001.
[6] Imaoka T, Horiguchi H, Yamamoto K. Metal assembly in novel dendrimers
with porphyrin cores. J Am Chem Soc 2003;125:340e1. http://dx.doi.org/
10.1021/ja0285060.
[7] Yan X, Goodson T, Imaoka T, Yamamoto K. Up-converted emission in a series
of phenylazomethine dendrimers with a porphyrin core. J Phys Chem B
2005;109:9321e9. http://dx.doi.org/10.1021/jp044105q.
[32] Stephanek P, Dukh M, Saman D, Moravcova J, Kniezo L, Monti D, et al. Syn-
thesis and solvent driven self-aggregation studies of meso-C-glycoside-
porphyrin derivatives. Org Biomol Chem 2007;5:960e70. http://dx.doi.org/
10.1039/B616096D.
[33] Ribo JM, Bofill JM, Crusats J, Rubires R. Point-Dipole approximation of the
exciton coupling model versus type of bonding and excitons in porphyrin
supramolecular structures. Chem Eur
J 2001;7:2733e7. http://dx.doi.org/
10.1002/1521-3765(20010702)7:13˂2733::AID-CHEM2733˃3.0.CO;2-Q.

120
E. Aguilar-Ortíz et al. / Dyes and Pigments 132 (2016) 110e120
[34] Micali N, Mallamace F, Castriciano M, Romeo A, Scolaro ML. Separation of
scattering and absorption contributions in UV/visible spectra of resonant
systems. Anal Chem 2001;73:4958e63. http://dx.doi.org/10.1021/ac010379n.
[35] Villari V, Mineo P, Scamporrino E, Micali N. Role of the hydrogen-bond in
porphyrin J-aggregates. RSC Adv 2012;2:12989e98. http://dx.doi.org/
10.1039/C2RA22260D.
[36] Lindsey JS, Schreiman CI, Hsu CH, Kearney CP, Marguerettaz MA. Rothemund
and Adler-Longo reactions revisited: synthesis of tetraphenylporphyrins un-
der equilibrium conditions. J Org Chem 1987;52:827e36. http://dx.doi.org/
10.1021/jo00381a022.
[38] Okada M, Kishibe Y, Ide K, Takahashi T, Hasegawa T. Convenient approach to
octa-glycosylated porphyrins via “click chemistry”. Int J Carbohydr Chem
2009;2009:1e9. http://dx.doi.org/10.1155/2009/305276.
[39] Maeda C, Kim P, Cho S, Park KJ, Lim MJ, Kim D, et al. Large porphyrin squares
from the self-assembly of meso-traizole-appenden L-shaped meso-meso-
linked Zn (II)-triporphyrins: synthesis and efficient energy transfer. Chem
Eur J 2010;16:5052e61. http://dx.doi.org/10.1002/chem.200903195.
[40] Roberts AD, Schmidt WT, Crossley JM, Perrier S. Tunable self-assembly of
triazole-linked porphyrin-polymer conjugates. Chem Eur
J
2013;19:
12759e70. http://dx.doi.org/10.1002/chem.201301133.
[37] Pore SV, Aher GN, Kumar M, Shukla KP. Design and synthesis of fluconazole/
bile acid conjugate using click reaction. Tetrahedron 2006;62:11178e86.
http://dx.doi.org/10.1016/j.tet.2006.09.021.
[41] Esch JH, Feiters MC, Peters AM, Nolte JM. UV-Vis, fluorescence, and EPR
studies of porphyrins in bilayers of dioctadecyldimethylammonium surfac-
tants. J Phys Chem 1994;98:5541e51. http://dx.doi.org/10.1021/j100072a022.