Efficient preparation of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin. Microwave assisted v/s conventional synthetic method, X-ray and hirshfeld surface structural analysis

Article abstract of DOI:10.1016/j.molstruc.2019.127139

The symmetrical meso-tetrasubstituted porphyrin 5,10,15,20-tetrakis(4-bromophenyl)Porphyrin (1) has been synthesized in quite high yields, ranging from 55 – 78%, by conventional and microwave assisted techniques, and isolated as a microcrystalline compound. The products obtained in each case have been characterized by ¹H NMR, Mass spectrometry, elemental analysis and Thin layer chromatography. The X-ray crystal structure of 1 is reported for the first time, and reveals a planar disposition of the center of the macrocycles with almost orthogonal 4-bromophenyl rings in the four meso-positions in the solid state. Hirshfeld surface (HS) analysis along with 2D fingerprint plots were employed to consider the intermolecular forces, including hydrogen bonds and π–π stacking interactions, and their quantification in the crystal lattice.

Full text of DOI:10.1016/j.molstruc.2019.127139

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Efficient preparation of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin. Microwave
assisted v/s conventional synthetic method, X-ray and Hirshfeld surface structural
analysis
Edison Matamala-Cea, Fabián Valenzuela-Godoy, Déborah González, Rodrigo Arancibia, Vincent
Dorcet, Jean-René Hamon, Néstor Novoa
PII:
S0022-2860(19)31248-7
DOI:
https://doi.org/10.1016/j.molstruc.2019.127139
MOLSTR 127139
Reference:
To appear in:
Journal of Molecular Structure
Received Date:
Accepted Date:
01 August 2019
26 September 2019
Please cite this article as: Edison Matamala-Cea, Fabián Valenzuela-Godoy, Déborah González,
Rodrigo Arancibia, Vincent Dorcet, Jean-René Hamon, Néstor Novoa, Efficient preparation of
5,10,15,20-tetrakis(4-bromophenyl)porphyrin. Microwave assisted v/s conventional synthetic
method, X-ray and Hirshfeld surface structural analysis, Journal of Molecular Structure (2019),
https://doi.org/10.1016/j.molstruc.2019.127139
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Graphical Abstract Synopsis
Improved yield conventional and Microwave assisted synthesis of 5,10,15,20-
tetrakis(4-bromophenyl)porphyrin, X-ray crystal structure and Hirshfeld surface Analysis of
supramolecular interactions are presented.

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Efficient preparation of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin.
Microwave assisted v/s conventional synthetic method, X-ray and
Hirshfeld surface structural analysis
Edison Matamala-Ceaa, Fabián Valenzuela-Godoya, Déborah Gonzáleza, Rodrigo
Arancibiaa, Vincent Dorcetb, Jean-René Hamonb,*, Néstor Novoaa,*
a
Laboratorio de Química Inorgánica y Organometálica, Departamento de Química
Analítica e Inorgánica, Facultad de Ciencias Químicas, Universidad de Concepción,
Edmundo
Larenas
129,
Casilla
160-C,
Concepción,
Chile.
b
Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) – UMR 6226,
F-35000 Rennes, France.
* Corresponding authors.
E-mail address: jean-rene.hamon@univ-rennes1.fr (J.-R. Hamon)
E-mail address: nenovoa@udec.cl (N. Novoa)

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Abstract:
The
symmetrical
meso-tetrasubstituted
porphyrin
5,10,15,20-tetrakis(4-
bromophenyl)Porphyrin (1) has been synthesized in quite high yields, ranging from 55 to
78%, by conventional and microwave assisted techniques, and isolated as a microcrystalline
compound. The products obtained in each case have been characterized by 1H-NMR, Mass
spectrometry, elemental analysis and Thin layer chromatography. The X-ray crystal structure
of 1 is reported for the first time, and reveals a planar disposition of the center of the
macrocycles with almost orthogonal 4-bromophenyl rings in the four meso-positions in the
solid state. Hirshfeld surface (HS) analysis along with 2D fingerprint plots were employed
to consider the intermolecular forces, including hydrogen bonds and π–π stacking
interactions, and their quantification in the crystal lattice.
Keywords
Meso-tetraporphyrins
Microwave assisted synthesis
Single crystal X-ray Diffraction
Hirshfeld Surface Analysis

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1. Introduction
Porphyrin, a square planar 18- aromatic macrocycle consisting of four pyrroles and four
methine carbons, is arguably the most significant pigment to be found in nature [1,2]. Owing
to the well-known advantageous properties such a structural robustness, attractive absorption
and emission properties, strong aromaticity and rich metal coordination chemistry,
porphyrins have been broadly used in a wide range of research disciplines [1–9]. The
recognition of porphyrins as molecular system susceptible to conjugative perturbations at the
periphery of the coordination center, allows rationalizing electronic fine-tuning
modifications in the molecular unit that affords systems displaying drastically altered optical
and electronic properties [1–9]. In this context, the extensive number of functionalizable
positions of the macrocycle (12) offers a large panel of possible molecular designs for
porphyrins [1,5] as ligands and metalloligands (see Chart 1). Particularly, the meso-
substituted porphyrins are relatively easy to prepare showing high versatility that allows
many possible designs for porphyrin-based ligands and derived coordination compounds.
However, the conventional methods to prepare this kind of substituted macrocycles give low
yield and use large volume of organic solvent and prolonged reaction times, often followed
by tedious chromatographic purification [10-13]. To circumvent these drawbacks,
solventless syntheses of meso-tetrasubstituted porphyrins have been reported, involving
either a two-step mechanochemical process (condensation followed by oxidation) [14], or
mixing the two reagents in the gas phase at very high temperature (>200°C) [15], or
microwave-mediated synthesis on solid support [16,17]. Nevertheless, those above methods
still suffer from low yields (1-25%). By contrast, variously substituted 5,10,15,20-
tetraarylporphyrins were shown to be readily accessible in yields up to 43% via microwave-
assisted cyclocondensation of different aryl aldehydes with pyrrole, using a minimum
amount of propionic acid [18]. Thus, microwave irradiation, also useful in metalloporphyrin
synthesis [17,19], appears as a straightforward one-pot practical methodology minimizing
reaction time, amount of solvent, and work-up problems.
Bromo substituted tetrapyrrolic derivatives, such as the symmetrical 5,10,15,20-
tetrakis(4-bromophenyl)porphyrin (1) prepared for the first time by J.B. Kim and co-workers
in the early 70’s in 12% isolated yield [20], have been broadly reported as very important
building blocks for molecular material applications by efficient bottom-up synthesis through

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organometallic methodologies, e.g. Heck [21,22], Sonogashira, Negishi, Stille, Suzuki,
Click, and others cross coupling reactions [22]. In this regard, this piece of work reports on
a comparison between a conventional heating two step synthesis v/s a microwave assisted
(one-pot) improved high yield (> 55%) synthesis of 1, its full analytical and spectral
characterization, and its crystallographic and Hirshfeld Surface study in the solid state.
Chart 1. Four meso- and eight -position available to modify the porphyrinic macrocycle.
2. Experimental Section
2.1. General considerations
All reactions were performed under dinitrogen atmosphere using standard Schlenk
techniques. The solvents were dried and distilled according to standard procedures [23]. 1H-
Pyrrole, propionic acid, 4-bromobenzaldehyde, BF3·OEt2 and p-chloranil were purchased
from commercial sources and used without further purification. Microwave reactions were
carried out in a Microwave Synthesizer Biotage® Initiator+. 1H NMR spectra were recorded
on a Bruker Advance 400 Digital Instrument. All NMR spectra are reported in parts per
million (ppm, ) relative to tetramethylsilane (Me4Si), with the residual solvent proton
resonances used as internal standards. Elemental analyses were measured on a Perkin Elmer
CHN Analyzer 2400. Mass spectra were obtained at the Laboratorio de Servicios Analíticos,
Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.

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Scheme 1. Synthesis of the 5,10,15,20-tetrakis(4-bromophenyl)porphyrin 1 via conventional and
microwave-mediated methods.
2.2. Preparation of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin (1):
2.2.1. Synthesis via modified conventional method
The reaction was carried out following an similar method to that reported by Drouet
et al for the synthesis of 5,10,15,20-tetrakis(4-trimethylsilylethynylphenyl)porphyrin [24]. A
two necked round bottom flask was loaded with a magnetic stir bar, 0.7 mL (10 mmol) of
freshly distilled 1H-Pyrrole, 1.85 g (10 mmol) of 4-bromobenzaldehyde and 100 mL of
CH2Cl2. Then, 0.4 mL (3.0 mmol) of BF3·OEt2 was added and the resulting mixture was
stirred vigorously at room temperature in the dark for 3 h. After that time, 1.84 g (7.50 mmol)
of p-chloranil was added to the reaction mixture that was refluxed for 1h. The resulting black
mixture was cooled at room temperature, filtered over a silica gel:celite® (1:1 ratio) mixture,
and rinsed several times with CHCl3. The collected fractions were concentrated under
vacuum, and the resulting black solid material was absorbed on silica gel (70 mesh, 256)
packed column, and eluted with CH2Cl2: hexane (7:3, v:v) mixture. The dark-purple band
was collected and the solvent was completely removed under reduced pressure, giving a
microcrystalline purple compound that was further dried under vacuum for 3 h. Yield: 512

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mg (0.55 mmol, 55%). 1H-NMR (CDCl3, 21ºC): 훿퐻 -2.85 (s, 2H, NH); 7.83 (d, 3J=8.2 Hz,
8H, H 3,5-phenyl); 7.99 (d, 3J=8.2 Hz, 8H, H 2,6-phenyl); 8.77 (s, 8H, H of β-pyrrole). MS:
m/z calc. for C44H2679Br4N4: 929.89; found: 929.80 [M+]. Anal. Calc. for C44H26Br4N4: C,
56.81; H, 2.82; N, 6.02. Found: C, 56.70; H, 2.65; N, 6.09. Recrystallization from vapor
diffusion of diethyl ether into CHCl3 solution of the compound for 7 days at room
temperature (1:5, v:v), afforded blue microcrystals of 1 suitable for single-crystal X-ray
diffraction.
2.2.2. Synthesis via Microwave assisted method
A vial was charged with 0.7 mL (10 mmol) of freshly distilled 1H-Pyrrole, 1.85 g (10
mmol) of 4-bromobenzaldehyde, 10 mL of CH2Cl2, and the appropriate volume of propionic
acid of each entry depicted in table 1. The vial was capped with Teflon, deposited in a
Microwave reactor for 2 minutes at 300 W, cooled and gently stirred at room temperature for
5 min, and put back in the Microwave reactor. This procedure was repeated ten times for
each trial, affording a black oil in each case. The crude products were purified using the same
chromatographic method described in the previous section. The obtained yields are listed in
1
table 1, and the isolated purple solids were authenticated by H NMR, Mass spectrometry
and Thin layer chromatography on silica gel (Rf = 0.95, CHCl3:petroleum ether 8:2 mixture
(v:v)).
Table 1 Reaction conditions for microwave assisted preparation of 5,10,15,20-tetrakis(4-
bromophenyl)porphyrin (1).
Entry
Time of reaction
Propionic acid
Yield (%)
(minutes)
volume (mL)
1
2
3
4
5
6
20
20
20
20
20
20
0.5
1.0
1.5
2.0
2.5
3.0
40
78
48
35
20
8

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2.3. X-ray structure determination
A well-shaped crystal of compound 1 was coated in Paratone-N oil, mounted on a
nylon loop and transferred to the cold gas stream of the cooling device. Intensity data were
collected at 150(2) K on a D8 VENTURE Bruker-AXS diffractometer equipped with a
multilayer monochromated Mo-K radiation ( = 0.71073 Å) and a CMOS Photon100
detector. The structure was solved by dual-space algorithm using the SHELXT program [25],
and then refined with full-matrix least-square method based on F2 (SHELXL-2014) [26]. The
contribution of the disordered diethyl ether molecules (four per unit cell) to the calculated
structure factors was estimated following the BYPASS algorithm [27], implemented as the
SQUEEZE option in PLATON [28]. A new data set, free of solvent contribution, was then
used in the final refinement. All non-hydrogen atoms were refined with anisotropic atomic
displacement parameters. H atoms were finally included in their calculated positions and
treated as riding on their parent atom with constrained thermal parameters. Crystal data and
details of data collection and refinement for 1 are summarized in table 2, and additional
crystallographic details are provided in the cif file (Supplementary data). ORTEP views were
drawn using OLEX2 software [29]. CCDC 1943145 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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Table 2 Crystallographic data, details of data collection and structure refinement parameters for
compound 1.
Empirical Formula
Formula mass, g mol-1
Collection T, K
Crystal size (mm)
Crystal color
crystal system
space group
a (Å)
C44 H26 Br4 N4
930.33
150(2)
0.33 x 0.16 x 0.15
Blue
Monoclinic
C 2/c
27.018(3)
6.1841(7)
26.339(4)
115.487(4)
630.5(5)
4
b (Å)
c (Å)
 (°)
V (Å3)
Z
Dcalcd (g cm-3)
F(000)
1.556
1832
abs coeff (mm-1)
 range (°)
4.088
3.028 to 27.476
-32/34, -8/8, -34/34
23992
range h,k,l
No. total refl.
No. unique refl.
Comp. max (%)
Max/min transmission
Data/Restraints/Parameters
4528
99.9
0.542 /0.446
4528 / 0 / 235
Final R
R1 = 0.0358
wR2 = 0.0726
[I>2(I)]
R indices (all data)
R1 = 0.0520
wR2 = 0.0784
Goodness of fit / F2
1.013
Largest diff. Peak/hole (eÅ-3) 1.578 d -1.389

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2.4 Hirshfeld Surface (HS) determination
The analyses of the surfaces were mapped using CrystalExplorer [30], starting from the
crystallographic information file (CIF) of 1. The normalized contact distance (dnorm), defined
in terms of de, di and the vdW raddi of the atoms, was calculated using Eq. 1, where the
distance from the HS to the nearest nucleus internal (di) or external (de), with respect to the
surface involved, and vdW is the van der Waals raddi of atoms, according to the literature
[31].
The dimensional (3D) HS map is generated by dnorm, and appear as red spots over a
surface of close-contact interactions, responsible of molecular packing in the crystal lattice.
Also, 3D dnorm surfaces can be plotted in 2D fingerprint representations, to quantitatively
summarize, the nature and type of all intermolecular interactions present in the crystal
packing. HS for 1, mapped over dnorm (range -0.1027 to 3.3089Å), are illustrated in figure 3
(section 3.5).
3.
3.1. Synthesis
The known symmetrical 5,10,15,20-tetrakis(4-bromophenyl)Porphyrin (1) [20] was
Results and Discussions
first synthesized according to a conventional heating method [32] upon mixing equimolar
amounts of 1H-Pyrrole and 4-bromobenzaldehyde in dichloromethane for 3 h, followed by
an oxidation step using an excess of p-chloranil under reflux for 1 h (Scheme 1). Upon work-
up and chromatographic purification, 1 was isolated as a microcrystalline purple solid in a
quite good yield of 55%. Interestingly, this yield can be increased to 78% under microwave
irradiation [17,18] for 20 min (Scheme 1 and section 2.2.2), after changing p-chloranil for
propionic acid (1 mL) in 10 mL of CH2Cl2 (entry 2 of Table 1). However, variation of the
amount of propionic acid has a dramatic impact on the yield of 1, that drops to 8% when an

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excess of the organic acid is used (entry 6). This is probably due to an increasing generation
of side and oxidation products, rendering difficult the purification and isolation of the
targeted macrocycle 1.
3.2. 1H NMR spectroscopy
1
It is relevant to note that in the vast majority of H NMR spectra of meso-substituted
porphyrins, the signals associated to the NH protons located in the center of the porphyrinic
ring are highly shielded, while the meso- and β-protons are unshielded due to the effect of
the diamagnetic anisotropy presented by the aromatic macrocycle [32]. This property
facilitates the identification of protons associated with the central nitrogen atoms that appear
at -2.85 ppm for compound 1, while those of the β-protons of the aromatic system show up
around 8.00 ppm. This molecular target being a symmetric tetraphenyl-porphyrin, the signals
observed in the spectrum can be analyzed in a simple way. One singlet for the protons in the
β-system and two doublets for the magnetically non-equivalent protons of the 4-bromophenyl
rings (see experimental section).
3.3. Description of the X-ray crystal structure
Single crystals suitable for X-ray structure investigation were obtained for the
symmetrical meso-porphyrin 1 by vapor diffusion techniques (see Experimental Section).
The molecular structure of 1 is displayed in Figure 1 with selected bond distances and angles
given in Table 3. The symmetrical meso-porphyrin 1 crystallizes in the centrosymmetric
space group C 2/c with half meso-porphyrin molecule per asymmetric unit, expanded by
symmetry operations -x, -y, -z (see fig. 1). The single-crystal X-ray diffraction study confirms
the formation of the tetra-substituted porphyrin through the condensation between 1H-
Pyrrole and 4-bromobenzaldehyde. The interatomic C-N (range: 1.372(3) - 1.375(4) Å) and
C-Br (1.907(3) and 1.898(3) Å) distances (see Table 3) are similar to others porphyrin- and
bromine-based molecules [17,33]. In addition, the C-C bond distance through the molecular
backbone reveals a strong -delocalization of the macrocycle in a network of sp2 hybridized
carbon atoms (Table 3). The connected four pyrrole fragment complete an almost planar core
with N(1) and N(2) atoms defining the N4 basal plane. In addition, the pyrrole (mean plane)
units shows a torsion angle of 10.75(2) and 4.03(2)º, respectively, with respect to the N4-core

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(mean plane). On the other hand, the torsion angles exhibited by the phenyl rings with respect
to the same core-plane are 66.54(1) and 56.50(1)º, respectively.
Fig. 1. Molecular structure of meso-porphyrin 1, top view (left) and side view (right), with partial
atom labelling scheme. Hydrogen atoms are omitted for clarity with exception of N-H fragments.
Thermal ellipsoids are drawn at 70% probability and half unit of 1 was generated by symmetry
operations -x, -y, -z.
Table 3 Selected bond distances (Å) and angles (°) for compound 1.
Bond distances
N(1)-C(1)
N(1)-C(4)
C(1)-C(10)#1
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(11)
C(14)-Br(1)
N(2)-C(6)
N(2)-C(9)
C(6)-C(5)
C(6)-C(7)
C(7)-C(8)
C(8)-C(9)
C(9)-C(10)
C(10)-C(17)
C(20)-Br(2)
1.372(3)
1.372(4)
1.407(4)
1.446(4)
1.351(4)
1.444(4)
1.404(4)
1.497(4)
1.907(3)
1.374(4)
1.375(4)
1.399(4)
1.434(4)
1.358(4)
1.433(4)
1.401(4)
1.496(4)
1.898(3)
Bond angles
C(1)-N(1)-C(4)
N(1)-C(1)-C(10)#1
N(1)-C(4)-C(5)
C(4)-C(5)-C(6)
C(1)-C(2)-C(3)
C(2)-C(3)-C(4)
C(6)-N(2)-C(9)
N(2)-C(6)-C(5)
N(2)-C(9)-C(10)
C(9)-C(10)-C(1)#1
C(6)-C(7)-C(8)
C(7)-C(8)-C(9)
106.60(2)
109.60(2)
126.40(3)
125.80(3)
107.10(3)
107.40(3)
108.60(2)
126.10(3)
125.40(3)
125.40(2)
107.40(3)
108.10(3)
Symmetry transformations used to generate equivalent atoms: #1 -x, -y, -z

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Fig. 2. (left) Inter- and intra-molecular H-bonds and (right) - close contact interactions determined
from the crystal packing of 1, showing a partial atom numbering scheme. Non relevant hydrogen
atoms are omitted for clarity. Thermal ellipsoids are drawn at 60% probability.
3.4. Solid-state supramolecular interactions
The molecules of 1 are connected through a series of intermolecular hydrogen bonds
(table 4 and figure 2). The projection of the packing shows an extended parallel-displaced
disposition, possibly attributable to the -stacking interactions between the aromatic systems
and the bromine atoms (table 4, and figure 2(right)) due to an intermolecular close contact
involving the two pyrrolic rings (Cg1 and Cg2), and between phenyl ring (Cg3) and one
bromine atom of each molecule. In addition, this arrangement can be explained by the
hydrogen bonds formed beside parallel-displaced molecular-chains (figure 2 (left)).
Table 4 Close contact interactions in crystal lattice of 1.
Hydrogen bond calculated by X-ray diffraction
Donor-H ··· Acceptor
D-H(Å)
H ··· A(Å)
D ··· A(Å)
D-H ··· A(°)
N(2)-H(2)··· N(1)a
C(12)-H(12)··· N(1)b
C(16)-H(16)··· Br(1)b
0.880(3)
0.950(3)
0.950(3)
2.360(2)
2.599(2)
3.170(5)
2.910(3)
3.384(4)
3.742(3)
120.8(2)
140.21(19)
120.5(2)
- stacking interactions determine by X-ray diffraction
Centroid-Centroid
Distance(Å)
3.768(16)
3.336(8)
Twist angle(º)
b
Cg1-Cg2
85.6(14)
3.00(2)
Cg3-Br(2)b
a intramolecular H-bond; b neighboring molecule; where: Cg1 = C6-(N2)-C9; Cg2 = C1-(N1)-C4; Cg3 = C11-C16.

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3.5. Hirshfeld Surface Analysis (HSA)
The supramolecular interactions observed by X-ray diffraction are, surely,
determined by indirect approximations. In this regard, performing HSA is a good way to
complement the presence of several intermolecular contacts. This analysis is defined as the
electron density boundary surfaces between the molecules in a crystal lattice [31].
During the mapping, the surfaces are kept transparent for the visualization of various
supramolecular interactions responsible for the packing stabilization. The HS of 1 mapped in
Fig. 3 shows the most important supramolecular interaction centered in the -CH and -Br
fragments (red spots), which highlights the close contact through which the intermolecular
interaction in the crystal lattice takes place. The color intensity can be used for visualizing
the strength of the interactions. In this regard, the most important interaction is that exhibited
by C-H···Br bond between two molecules, over the weaker interactions C-H···N previously
described in Table 4.
Accordingly, the analysis of the HS plots obtained for 1, shows two important red
spots (see figure 3), corresponding to C-H···Br interactions, and are more important than the
present C-H···N interactions previously described in table 4 (light-red spots). On the other
hand, the analysis of the expansion pack considering the most important interactions (red
spots), reveals the important role of these close contact interactions in 1 (fig. 4). This
important supramolecular interaction provides high thermal and moisture stability to the
crystal packing, and allows us to project this type of complexes for diverse applications in
solid phase. The crucial role of these close contact interactions can be contrasted by the
analysis of the fingerprint plots (fig. 5). The most relevant C-H···Br interactions, present in
the crystal packing, represent the 32.5% over the total HS (fig. 5, left and middle). In this
context, the 2D fingerprint plots are useful in the quantification of different interactions. The
plots of 1 (fig. 5) shows the H···Br interactions with a shortest de + di distance ~3.00 Å, and
the 23.3% (including the reciprocal contacts) of the total HS. In addition, the most abundant
close contact interaction at long distance is H···H with a 40.1% of the total HS. Finally, the
presence of ··· stacking interactions are evidenced by de + di ≈ 3.50Å (4.6% C···C + 2.7%
C···N) (figure 2). Considering this analysis, the most important supramolecular interactions,
responsible of the stability of the crystal lattice, are the CH···Br and CH···N close contacts.

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Fig. 3. Views of the dnorm Hirshfeld surface plotted for 1. Intermolecular H-bonds are described in
Table 4 and text.
Fig. 4. Relevant hydrogen bond (left) and close contact Br···C interactions (right) determined by HS
plotted over dnorm for the crystal packing of 1. Thermal ellipsoids are drawn at 20% probability.

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Fig. 5. Decomposed fingerprint plots related with HS areas and contributions (including reciprocal
contacts) to the total HS for close contact interactions of C···H(left), Br···H (middle), and
C···Br(right) present in the crystal packing of 1.
4. Conclusions
In this paper, the 5,10,15,20-tetrakis(4-bromophenyl)Porphyrin (1) is successfully
prepared by conventional and microwave assisted techniques, characterized and monitored
by means of various physical methods. The microwave assisted preparation gives quite high
yields in the preparation of this precursor, decreasing the presence of side-products in the
synthesis, and reducing the reaction time and volume of organic solvent used. Also, the
crystal structure of this macrocyclic compound has been studied. It is shown that the solid-
state structures are influenced by the intermolecular interactions. The presence of several
intermolecular contacts, including hydrogen bonds and ··· stacking close contact
interactions were visually gained by Hirshfeld Surface analysis. 2D fingerprint plots provided
an estimation of the influence of such interactions on the crystal lattice and stability. The
synthetic versatility and simplicity of the microwave assisted approach, allowing a facile
scale-up of the procedure, depicted here suggest application in the chemical design of
selective molecular scaffolds for multi-centered binding and reactivity in coordination and
organometallic chemistry.

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Acknowledgements
Financial support from the Fondo Nacional de Desarrollo Científico y Tecnológico
[FONDECYT (Chile), grant No. 11160658 (IR: N.N.)] and the Vicerrectoría de
Investigación y Desarrollo, Universidad de Concepción (Chile), grant VRID Iniciación No.
216.021.034-10-1.0IN (IR: N.N.), the CNRS and the Université de Rennes 1 is gratefully
acknowledged. This research has been performed as part of the Chilean-French International
Associated Laboratory for “Multifunctional Molecules and Materials“ (LIA M3-CNRS
N°1207). F.V-G. thanks also the CONICYT (Chile) for support of a National Master
Scholarship (UdeC). E. M-C. thanks also the FONDECYT (Chile), grant No. 11160658 for
support of a undergraduate scholarship (UdeC).
Appendix A. Supplementary data
Supplementary
data
to
this
article
can
be
found
online
at
https://doi.org/10.1016/j.molstruc.2019.xx.xxx.
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Appendix A. Supplementary data
The following is the Supplementary data to this article:
Crystallographic data for the structural analysis have been deposited with the Cambridge
Crystallographic Data Centre, CCDC reference number: 1943145 for (1). This 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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HIGHLIGHTS
► High yield preparation of 5,10,15,20-tetrakis(4-bromophenyl)porphyrin
► Microwave-assisted synthesis reducing reaction time and volume of organic solvents
► Crystal structure of the symmetrical meso-tetrasubstituted porphyrin
► 2D fingerprint plot and Hirshfeld surface analysis of intermolecular interactions