Rigid trisporphyrin with 1,3,5-triazine core: Synthesis, spectroscopy, and DABCO-induced self-assembly properties

Article abstract of DOI:10.1142/S1088424620500236

A rigid Zn-trisporphyrin (1), the Zinc complex of 2,4,6-tris(5,10,15-triphenylporphyrinatozinc)-1,3,5-triazine (2) with three porphyrin moieties bridged by a rigid 1,3,5-triazine group, was synthesized and characterized by a series of spectroscopic methods including mass, 1H NMR, electronic absorption, and IR spectroscopy in addition to elemental analysis. The UV-vis spectrophotometric titration results revealed that along with the addition of the 1,4-diazabicyclo[2.2.2]octane (DABCO) form 0 to 3 equiv, 1 could form a 2:3 sandwich-type coordination cage in chloroform, which then transformed into a 1:3 open complex when the DABCO concentration was more than 3 equiv. Such DABCO-induced self- and disassembly processes were also confirmed by 1H NMR spectrophotometric titrations. In particular, it was demonstrated by comparative studies that the synergistic effect of the three porphyrin moieties linked together by the rigid 1,3,5-triazine group in 1 promoted the formation and stabilization of the 2:3 sandwich-type coordination cage. This result will be helpful towards the fabrication of various self-assembly structures based on metalloporphyrins with application potential in diverse areas such as molecular recognition and separation.

Full text of DOI:10.1142/S1088424620500236

This is a JAM - Just Accepted Manuscript
Journal of Porphyrins and Phthalocyanines
Article Title:
Rigid Trisporphyrin with 1,3,5-Triazine Core: Synthesis, Spectroscopy, and
DABCO-Induced Self-Assembly Properties
Author(s):
DOI:
Chunhua Huang, Bin Shen, Kang Wang, Jing'an Lu and Xiao'fei Sun
10.1142/S1088424620500236
To be cited as:
Chunhua Huang, Bin Shen, Kang Wang, Jing'an Lu and Xiao'fei Sun, Rigid Trisporphyrin with
1,3,5-Triazine Core: Synthesis, Spectroscopy, and DABCO-Induced Self-Assembly Properties,
Journal of Porphyrins and Phthalocyanines, doi: 10.1142/S1088424620500236
Received: 27 March 2020
Accepted: 28 April 2020
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Rigid Trisporphyrin with 1,3,5-Triazine Core: Synthesis,
Spectroscopy, and DABCO-Induced Self-Assembly Properties
Chunhua Huang, *a Bin Shen,a Kang Wang*b, Jing’an Lu,c and Xiao’fei Sund
aNational Research Center for Geoanalysis, China Geological Survey, Beijing 100037, China
bBeijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department
of Chemistry, University of Science and Technology Beijing, Beijing 100083, China
cMNR Key Laboratory of Marine Mineral Resources, Guangzhou Marine Geological Survey, Ministry of Natural
Resources, Guangzhou, Guangdong 510075, China
dNCS Testing Technology Co., Ltd, Beijing 100081, China
Received date (to be automatically inserted after your manuscript is submitted)
Accepted date (to be automatically inserted after your manuscript is accepted)
ABSTRACT:
A
rigid Zn–trisporphyrin (1), the Zinc complex of 2,4,6-tris(5,10,15-
triphenylporphyrinatozinc)-1,3,5-triazine (2) with three porphyrin moieties bridged by a rigid 1,3,5-
triazine group, was synthesized and characterized by a series of spectroscopic methods including mass,
1H NMR, electronic absorption, and IR spectroscopy in addition to elemental analysis. The UV-vis
spectrophotometric titration results revealed that along with the addition of the 1,4-
diazabicyclo[2.2.2]octane (DABCO) form 0 to 3 equiv, 1 could form a 2:3 sandwich-type coordination
cage in chloroform, which then transformed into a 1:3 open complex when the DABCO concentration
was more than 3 equiv. Such DABCO-induced self- and disassembly processes were also confirmed by
1
the method of the H NMR spectrophotometric titrations. In particular, it was demonstrated by the
comparative studies that the synergistic effect of the three porphyrin moieties linked together by the rigid
1,3,5-triazine group in 1 promoted the formation and stabilization of the 2:3 sandwich-type coordination
cage. This result will be helpful towards the fabrication of various self-assembly structures based on
metallporphyrins with application potential in diverse areas such as molecular recognition and separation.
KEYWORDS: Trisporphyrin, Synthesis, DABCO, Self-Assembly.
*Correspondence to:Chunhua Huang, email: mnhuangchunhua@126.com and Kang Wang, email: kangwang@ustb.edu.cn

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INTRODUCTION
With abundant coordination sites, excellent binding affinity and highly tuneable structures, oligometallporphyrins are
considered as one kind of remarkable precursors in supramolecular chemistry[1]. Up to now, many covalently linked
oligometallporphyrins such as metalloporphyrin dendrimers[2], double-strand conjugated porphyrin ladders[3], double-
decker porphyrin[4], face-to-face porphyrin array[5], cyclic porphyrin[6], and tetra-porphyrin molecular[7], have been
used for the assembly of various supramolecular structures, which exhibit great application potential in diverse areas
including photoinduced electron transfer[8], catalysis[9], and cooperative molecular recognition[10,11]. Among these
supramolecular structures, the sandwich-type coordination cages formed by the trisporphyrins assembled with various
bidentate ligands have attracted a great research interest and been subjected to intensive study. In 2003, Joost and
coworkers obtained a sandwich-type structure complex with the assembly of two (zinc(II) porphyrin)phosphite ligands
and three ditopic 1,4-diazabicyclo[2.2.2]octane (DABCO) ligands with transition-metal catalyst leads to a
supramolecular chelating bidentate ligand. This chelate effect was responsible for the high selectivity for the linear
aldehyde in the rhodium-catalyzed hydroformylation of 1-octene[12]. Both Christopher and Lucia groups then
researched the thermodynamic mechanism of the DABCO-directed self-assembly of the Zn trisporphyrins to form a
stable 2:3 double-decker molecular coordination cage[13,14]. However, only the trisporphyrins with a flexible linkers
were used in the previous reports, to the best our knowledge, whereas the rigid trisporphyrins are supposed to be a more
ideal block for building a regular stereoscopic structure with a bidentate ligand.
<scheme 1>
Herein, a rigid Zn–trisporphyrin (1), the Zn complex of 2,4,6-tris(5,10,15-triphenylporphyrinatozinc)-1,3,5-triazine
(2) with three porphyrin moieties bridged by a rigid linker of 1,3,5-triazine, was synthesized and characterized by a
series of spectroscopic technologies including mass, 1H NMR, electronic absorption, and IR spectroscopy in addition to
elemental analysis, Scheme 1. In particular, the DABCO-directed self-assembly of the as-prepared Zn–trisporphyrin 1
was also investigated by the method of UV-vis and 1H NMR spectrophotometric titration. The UV-vis
spectrophotometric titration results demonstrated that a 2:3 sandwich-type coordination cage was gradually formed
along with the addition of the DABCO into the solution of 1 from 0 to 3 equiv and then transformed to a 1:3 open
complex 4 when the DABCO concentration was more than 3 equiv, Scheme 2. Such DABCO-induced self- and
disassembly processes were further confirmed by the 1H NMR spectrophotometric titration results. Moreover,
comparative studies revealed the significant synergistic effect of the three porphyrin moieties linked together by the
rigid 1,3,5-triazine group in 1 on promoting the formation and stabilization of the 2:3 sandwich-type coordination cage.
<scheme 2>
RESULTS AND DISCUSSION
Synthesis
Synthesis path of 1 are shown in Scheme 1. According to the published procedure, mixed cyclic tetramerization of
benzaldehyde, p-cyanobenzaldehyde, and pyrrole in propionic acid for 2h provided the metal free 5,10,15-triphenyl-(4-
cyanophenyl)porphyrin (H2TPCNPP) in a yield of 5.5% with compound tetraphenylporphyrin (H2TPP) as a by-product
in a yield of 10%. Subsequently, H2TPCNPP underwent a trimerization reaction in chloroform with the presence of
trifluoromethanesulfonic acid, which afforded the trisporphyrin 2 in a yield of 10%[15-17]. Reaction of this metal free
compound 2 with Zn(OAc)2 in the mixed solution CHCl3/CH3OH (v/v, 1/1) at room temperature for 10 h led to the
isolation of 1 in a yield of 76%. The newly prepared trisporphyrins 1 and 2 were characterized by MALDI-TOF mass,

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1H NMR, electronic absorption, and IR techniques in addition to elemental analysis. The MALDI-TOF mass spectra of
both 1 and 2 show an intense cluster corresponding to the molecular ion (M+), Figure S1 (Supporting Information).
<Fig.1>
1
Excellent H NMR spectrum was obtained for the Zn trisporphyrin 1 and the metal-free compound 2 in CDCl3,
1
Figure 1. With the assist of the H-1H COSY spectrum in Figure 1b, all the signals could be clear identified with the
result detailed in Table S1 (Supporting Information). As can be seen, the 1H NMR spectrum of 2 exhibited two doublet
singlets at δ = 9.43-9.45 (d, 6H) and 8.57-8.59 (d, 6H) ppm due to the β-pyrrole protons Ha and He, respectively, while
the other β-pyrrole proton Hd signal appears at δ = 8.86 (m, 12H). The broad peaks at δ = 8.24-8.26 (m, 18H) and 7.79
(m, 27H) ppm, which are correlated with each other in the 1H-1H COSY spectrum, are attributed to the aromatic protons
Hf and Hg of the meso-phenyl substituent. The signals of the the aromatic protons Hb and Hc of the phenyl linking with
triazine are observed at δ = 9.03 (m, 6H) and 8.94 (m, 6H) ppm, respectively. Then the singlet signal at δ = -2.71 (s, 6H)
is due to the protons of Hinner, Figure S2. As for compound 1, its 1H NMR spectrum is similar with that of the compound
2 with slightly downfield shift, which are therefore assigned in a similar approach, Figure 1 and Table S1 (Supporting
Information). As shown in Figure S2, the doublet signals appearing at δ = 9.43-9.45 (d, 6H), 9.13-9.14 (d, 6H), 9.04-
9.05 (d, 6H), and 8.58-8.60 (d, 6H) ppm in the spectrum of compound 1 can be assigned to the protons Ha', Hb', Hc' and
He'. The broad peak at δ = 8.97 (m, 12H), 8.25-8.26 (m, 18H), and 7.77-7.78 (m, 27H) ppm is attributed to the protons
of Hd', Hf', and Hg'. For comparative studies, the 1H NMR spectra of monoporphyrins H2TPCNPP and ZnTPP were also
recorded, as detailed in Figures S3-S5 and Table S1 (Supporting Information). It worth noting that the signals of
protons for trisporphyrin 1 were shifted to downfield compared to corresponding monoporphyrin ZnTPP due to
enlargement in the conjugated electronic structure of these trisporphyrin compounds.
UV-vis Spectrophotometric Titration
<Fig.2>
The binding properties of the rigid trisporphyrin 1 in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) was
first investigated by using UV-vis spectroscopy (trisporphyrin concentration 1×10-5 M) in CHCl3. For comparative
studied, the assembly of tetraphenylzincporphyrin (ZnTPP) induced by DABCO coordination was also performed in the
same condition. Both trisporphyrin 1 and ZnTPP exhibit a typical electronic absorption feature of porphyrinato metal
complexes including an intense Soret band at ca. 421 nm and weak Q bands at ca. 548 and ca. 586 nm, Figure S6
(Supporting Informaiton). Nevertheless, along with the gradual addition of DABCO into the ZnTPP solution, the band
at 419 nm gradually decreased and the band at 429 nm increased, revealing only a 1:1 open complex
(ZnTPP)1(DABCO)1 was formed during the titration process, Figure 2a and S7 (Supporting Informaiton), in line with
the previously reported results[13,18]. The addition of 0-3 equiv DABCO into a chloroform solution of trisporphyrin 1
at the concentration 1×10-5 M results in an initial red shift of the Soret band from 421 to 427 nm, Figure 2b. Such 6 nm
red shifts could be attribute to the formation of a 2:3 sandwich-type coordination cage 3 as shown in Scheme 2. With
further adding more than 3 equiv DABCO into the solution of 1, the band at 427 nm started to decrease, and a new band
appeared at 431 nm, which suggested the degeneration of the 2:3 sandwich-type coordination cage 3 and the formation
of a 1:3 open complex 4 with a trisporphyrin 1 monocoordinated to DABCO during the titration process, Scheme 2.
Moreover, the titration process of ZnTPP and 1 with DABCO was further evaluated by the change of absorbance of the
absorption peaks upon addition of DABCO, Figure 3. Figure 3b shows the change of absorbance at 421, 427, and 431
nm for the titration of 1 with DABCO. It can be found that three phases of the titration including the rise of the 2:3
sandwich-type coordination cage 3, concentration range of DABCO where 3 is stable, and finally dissociation of 3 were
observed form 1 to the open complex 4 with the gradual addition of DABCO. In contrary, only two phases appeared for
ZnTPP, corresponding to the rise of the open complex (ZnTPP)1(DABCO)1 and concentration range of DABCO where

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this complex is stable, as shown in Figure 3a. These results suggest that the synergistic effect of the three porphyrin
moieties in 1, which are linked together by the rigid 1,3,5-triazine group, promotes the formation of the 2:3 sandwich-
type coordination cage during the titration process. Furthermore, according to the reported metheds[12-14,18,19], the
Uv-vis titration data of 1 with DABCO were further analyzed by using global multivariae factor analysis considering
only three species (trisporphyrin 1, 2:3 sandwich-type coordination cage 3 and 1:3 open complex 4). Based on the
fitting of the titration data to the binding model described in Scheme 2[12-14,18,19], the binding constants K32 for 3 and
K31 for 4 were calculated to be (1.67 ± 0.20) × 1021 M-4 and (1.1 ± 0.08) × 1014 M-3, respectively (more details present
in the Experimental). For comparative study, the binding constant K11 for the the complex (ZnTPP)1(DABCO)1 was
aslo calculated to be 1.0 × 104 M-1 by the same method. Noted, the formation of 3 is able to be described by an
intermolecular association constant (Km) and two effective molarity (EM) values which are close to each other[12-14]:
6
K32 = Km EM2
Where Km = K11/2. As a result, the geometric average of the EM values is 0.3 M, confirming the synergistic effect of
the three porphyrin moieties in 1[12-14]. In addiiton, the speciation profiles during the UV-vis titration for both ZnTPP
and 1 with DABCO were also simulated, Figures 3c and 3d. It can be seen that 3 is generated along with adding
DABCO, and subsequent disintegrate to 4, while only the formation of (ZnTPP)1(DABCO)1 was observed along with
adding DABCO, in line with the above analysis for spectrometric titration curves.
<Fig.3>
NMR spectroscopic titration
<Fig.4>
In order to further understand the DABCO-induced self-assembly of the trisporphyrin 1, we further studied the
complexation of DABCO to the trisporphyrin 1 by using 1H NMR spectroscopy at 297 K and 237 K, Figures 4 and S8
(Supporting Information). At 297 K, the signals for all the protons of 1 except Ha' at δ = 9.43-9.45 upfield shifted with
the increase of the DABCO concentration from 0 to 1.6 equiv, suggesting the enhanced shielding effect owing to the
proximity of the two porphyrin π-systems in the sandwich-type coordination cage 3, Figure 4a. Along with adding more
DABCO, these signals of aromatic protons downfield shifted, implying the degeneration of the sandwich-type
coordination cage 3 and the formation of the open complex 4, in agreement with the UV-vis spectrophotometric
titration results. This is also supported by analyzing the signals for methylene protons of DABCO. As can be seen in
Figure 4b, the methylene protons of DABCO intrinsic signal at δ = 2.79 ppm appeared at δ = -4.63 ppm when the
concentration of DABCO was less than 1.8 equiv, corresponding to the methylene protons of a DABCO molecule
bound between two zinc–porphyrin units[13,18], confirming the formation of the sandwich type complex 3. However,
when the concentration of DABCO was more than 1.8 equiv, the signals for methylene protons of DABCO broadened,
which was hardly observed, probably owing to fast exchange between the sandwich type complex 3 and open complex
1
4. In order to better resolve the signals for the methylene protons of DABCO, H NMR titrations were performed at a
lower temperature of 237 K to slow exchange process between different complexes, Figure S8 (Supporting Information).
At 237 K, the signals for the methylene protons of DABCO were still observed at δ = -4.63 ppm, when the
concentration of DABCO was below 1.5 equiv, revealing the only formation of the 2:3 sandwich-type complex 3.
Along with increasing the DABCO to 1.5 equiv, a new signal at δ = -2.90 ppm appeared, which represents the DABCO
methylene protons in the α-position with respect to the nitrogen atom that is bound to the zinc–trisporphyrin in the open
complex 4[18]. With further adding DABCO, the signal at δ = -2.90 ppm increased along with the expense of the
signals at δ = -4.63 ppm, indicating that sandwich-type complex 3 gradually transformed into the open complex 4 when
the DABCO concentration was more than 1.5 equiv. In a word, when the DABCO concentration was in the range of 0-
1.5 equiv, 1 and DABCO almost quantitatively assembled into the 2:3 sandwich-type complex 3, while along with the

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DABCO concentration further increased, the sandwich-type complex 3 degenerated and the open complex 4
simultaneously formed.
EXPERIMENTAL
General
Chloroform was distilled using CaH2 in nitrogen atmosphere. Column chromatography was performed on silica gel
(Merck, Kieselgel 60, 70-230 mesh) with the pre-made eluents. All reagents and solvents were used as purchased from
suppliers.
1H NMR spectra were obtained through a Bruker DPX 400 spectrometer in CDCl3. Spectrum was referenced
1
internally using the resonances of SiMe4 (δ = 0 for H NMR). UV-vis absorption spectra were acquired by using a
Hitachi U-4100 spectrophotometer. IR spectra were obtained as KBr pellets using a Bruker Tensor 37 spectrometer
with 2 cm-1 resolution. Elemental analyses were carried out on an Elementar Vavio El III. MALDI-TOF mass spectra
were recorded on a Bruker BIFLEX III ultrahigh-resolution Fourier transformion cyclotron resonance (FT-ICR) mass
spectrometer with alpha-cyano-4-hydroxycinnamic acid as matrix.
1H NMR titrations were carried out by running a spectrum of the host solution in CDCl3 at a concentration around
0.8 mM for compound 1 and adding to it incremental aliquots of guest solution also in CDCl3 at 297 K and 273 K. After
each addition with 10 μL interval, a new NMR spectrum was acquired. The different concentrations of DABCO (0.01
M ~ 0.10 M) using CDCl3 were perpared for these titrations.
The UV-vis titrations were performed by the similar operation methodology as 1H NMR titrations. In this case, the
host concentration was 10 μM for compound 1 and 30 μM for ZnTPP. A new UV-vis spectrum was obtained after each
addition of guest with 10 μL interval. To cover a wide range of DABCO concentrations (0.01 M ~ 1.0 M), it was
necessary to prepare several solutions with different concentrations.
The data obtained form the UV-vis spectrophotometric titrations were analyzed by fitting the whole series of spectra
at 1 nm interval reported method[12-14,18,19] which uses global multivariae factor analysis to obtain globally
optimized parameters. In this method, the equilibrium constnats of the corresponding following equilibrium reactions
are defined as below:
K31 = [4]/[DABCO]3[1]
K32 = [3]/[DABCO]3[1]2
K33 = K(31)2/K32
K11 = [(ZnTPP)1(DABCO)1]/[DABCO][1]
Synthesis
Preparation of 5,10,15-triphenyl-(4-cyanophenyl)porphyrin (H2TPCNPP).
Benzaldehyde (7.42 g, 0.07 mol) and p-cyanobenzaldehyde (1.27 g, 0.01 mol) were mixed in propionic acid (350 mL)
and then heated to reflux. The propionic acid solution of pyrrole 10 mL (3 mL pyrrole) was slowly added into the above
mixed solution drop by drop in 1 h, and then the reaction mixture continued to react for 2h. After cooled down to room
temperature, the solvent were removed through filtration and washed by using methanol for three times. The residue
was chromatographed on a silica gel column using CHCl3/n-hexane with the n-hexane content gradually reducing from
30 to 0 vol% as the eluent. Repeated chromatography followed by recrystallization from CHCl3 and n-hexane gave
H2TPCNPP as purple powder . Yield 350 mg (5.5%). Anal. calcd. for C45H29N5·CHCl3: C 72.78, H 3.98, N 9.23%;
found: C 72.60, H 4.01, N 9.22%; IR (KBr): νmax, cm-1 3313, 3048, 3021, 2229, 1595, 1554, 1469, 1439, 1397, 1348,
1211, 1177, 1155, 1071, 1053, 1028, 980, 964, 793, 726, 695, 565; 1H NMR (400 MHz, CDCl3), δ ppm: 8.85-8.89 (m,

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6H, β-pyrrole protons Ha), 8.72-8.73 (d, 2H, aromatic protons Hb), 8.33-8.35 (d, 2H, aromatic protons Hc), 8.20-8.22 (d,
2H, β-pyrrole protons Hd), 8.05-8.07 (d, 2H, β-pyrrole protons He), 7.74-7.81 (m, 9H, aromatic protons Hf), -2.79 (s, 2H,
pyrrole-NH Hinner); MS (MALDI-TOF): m/z 639.80 (calcd. for [M]+ 639.75).
Preparation of 2,4,6-tris(5,10,15-triphenylporphyrin)-1,3,5-triazine (2).
H2TPCNPP (50 mg, 0.078 mmol) in 0.3 ml chloroform was added in small portions to 0.3 ml (0.50 g, 3.4 mmol)
trifluoromethanesulfonic acid at 0-10 oC. The orange solution was added in water and extract with chloroform for three
times. After the removing of the volatiles under reduced pressure, the residue was chromatographed on a silica gel
column by using CHCl3/n-hexane with the n-hexane content gradually reducing from 50 to 0 vol% as the eluent.
Repeated chromatography and biobead chromatography followed by recrystallization from CHCl3 and n-hexane gave 2
as purplish pink powder. Yield 5.0 mg (10%). Anal. calcd. for C135H87N15·0.5CHCl3: C 82.24, H 4.46, N 10.62%;
found: C 82.27, H 4.56, N 10.52%; IR (KBr): νmax, cm-1 3313, 3054, 3024, 2920, 2849, 2361, 1597, 1574, 1514, 1471,
1439, 1401, 1368, 1349, 1220, 1212, 1177, 1153, 1071, 1052, 1031, 1019, 1000, 981, 966, 797, 727, 698, 558, 525; 1H
NMR (400 MHz, CDCl3) ,δ ppm: 9.43-9.45 (d, 6H, β-pyrrole protons Ha), 9.03 (m, 6H, aromatic protons Hb), 8.94 (m,
6H, aromatic protons Hc), 8.86 (m, 12H, β-pyrrole protons Hd), 8.57-8.59 (d, 6H, β-pyrrole protons He), 8.24-8.26 (m,
18H, aromatic protons Hf), 7.79 (m, 27H, aromatic protons Hg), -2.71 (s, 6H, pyrrole-NH Hinner); MS (MALDI-TOF):
m/z 1919.95 (calcd. for [M]+ 1919.24).
Preparation of the Zn complex of 2,4,6-tris(5,10,15-triphenylporphyrinatozinc)-1,3,5-triazine (1).
Compound 2 (20 mg, 0.01 mmol) and zinc acetate (18 mg, 0.1 mmol) were added in mixed solution CHCl3/CH3OH
(v/v, 1/1) at room temperature for 10h. After the volatile components were removed by vacuum filter, the remaining
material was column chromatographed on a silica gel using CHCl3 as the eluent. Repeated chromatography followed by
recrystallization from CHCl3 and n-hexane gave 1 as purplish pink powder. Yield 16 mg (76%). Anal. calcd. for
C135H87N15Zn3·CHCl3: C 73.09, H 3.97, N 9.40%; found: C 73.10, H 4.01, N 9.42%; IR (KBr): νmax, cm-1 3051, 3025,
2918, 2848, 2363, 1597, 1573, 1514, 1488, 1440, 1403, 1359, 1339, 1206, 1176, 1069, 1002, 840, 797, 751, 719, 701,
1
660, 643, 568, 530; H NMR (400 MHz, CDCl3) ,δ ppm: 9.43-9.45 (d, 6H, β-pyrrole protons Ha’), 9.13-9.14 (d, 6H,
aromatic protons Hb’), 9.04-9.05 (d, 6H, aromatic protons Hc’), 8.97 (m, 12H, β-pyrrole protons Hd’), 8.58-8.60 (d, 6H,
β-pyrrole protons He’), 8.25-8.26 (m, 18H, aromatic protons Hf’), 7.77-7.78 (m, 27H, aromatic protons Hg’); MS
(MALDI-TOF): m/z 2109.35 (calcd. for [M]+ 2109.36).
CONCLUSION
In summary, we prepared a rigid Zn–trisporphyrin with three porphyrin moieties bridged by a 1,3,5-triazine group.
The self-assembly process for compound 1 with DABCO was monitored by the UV-vis and 1H NMR
spectrophotometric titration. It is demonstrated that a stable 2:3 sandwich-type coordination cage could form by the
self-assembly of 1 and DABCO, owing to the synergistic effect between the three porphyrin moieties linked together by
the rigid 1,3,5-triazine group in 1. This result will be helpful towards the fabrication of various self-assembly structures
based on metallporphyrins with application potential in diverse areas such as molecular recognition and separation.
Acknowledgements

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Financial support from China Geological Survey (Grant Number: DD20190226, DD20190229, DD20190086), the
National Natural Science Foundation of China (No 21871024), and the Fundamental Research Funds for the Central
Universities.
Supporting information
A full list of MALDI-TOF mass spectra of 1 and 2, 1H NMR spectra of 1, 2, and ZnTPP, 1H NMR and H-H COSY
1
spectra of H2TPCNPP, H NMR spectra of compound 1 recorded during the titration at 237 K are given in the
supplementary material. This material is available at http://www.u-bourgogne.fr/jpp/ or from the authors.
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Fig. 1. The 1H NMR spectra of 1 and 2 (a) and 1H-1H COSY spectrum of 2 (b).

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Fig. 2. The UV-vis spectral change along with the titration of ZnTPP at 3×10-5 M (a) and 1 at 1×10-5 M (b) with DABCO.

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Fig. 3. The change of absorbance of the absorption peaks versus the log([DABCO]/[ZnTPP]) (two wavelengths: 419 and 429 nm) (a)
and log([DABCO]/[1)] (three wavelengths: 421, 427, and 433 nm) (b), respectively. Simulated speciation profiles for titrations of
ZnTPP (c) and 1 (d) with DABCO.

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1
Fig. 4. The H NMR spectra of compound 1 (a) and the methylene region of DABCO (b) recorded during the titration of 1 with
DABCO in CDCl3 at 297 K.

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Scheme 1. Synthetic route of Zn–trisporphyrin 1

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Scheme 2. Schematic representation of the species involved in the binding of DABCO to trisporphyrin 1.

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Supporting Information
Rigid Trisporphyrin with 1,3,5-Triazine Core: Synthesis, Spectroscopy,
and DABCO-Induced Self-Assembly Properties
Chunhua Huang, Bin Shen, Kang Wang, Jing-an Lu and Xiao-fei Sun
1

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Fig. S1. MALDI-TOF mass spectra of 1 (a) and 2 (b). Insets show the experimental
isotopic patterns.
2

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Fig. S2. H NMR spectra of 1 and 2 recorded in CDCl3. ※denotes the solvent
1
impurity.
3

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Fig. S3. H NMR spectra of H2TPCNPP recorded in CDCl3. ※denotes the solvent
1
impurity.
4

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Fig. S4. 1H NMR (a) and 1H-1H COSY (b) spectra of H2TPCNPP recorded in CDCl3.
5

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Fig. S5. H NMR spectra of ZnTPP recorded in CDCl3. ※denotes the solvent
1
impurity.
6

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Fig. S6. The UV-vis absorption spectra of ZnTPP (a) and 1 (b).
7

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Fig. S7. Schematic representation of the species involved in the binding of DABCO
to ZnTPP.
8

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1
Fig. S8. The H NMR spectra of compound 1 (a) and the methylene region of
DABCO (b) recorded during the titration of 1 with DABCO in CDCl3 at 237K.
9

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Table S1. 1H NMR data () and assignments of 1 and 2 together with H2TPCNPP and ZnTPP in CDCl3.
Compound
1
Ha
Hb
Hc
Hd
He
Hf
Hg
Hinner
9.43-9.45
(d, 6H)
9.43-9.45
(d, 6H)
8.85-8.89
(m, 6H)
8.94
9.13-9.14
(d, 6H)
9.03
9.04-9.05
(d, 6H)
8.94
8.97
8.58-8.60
(d, 6H)
8.25-8.26
(m, 18H)
8.24-8.26
(m, 18H)
7.74-7.81
(m, 9H)
7.77-7.78
(m, 27H)
7.79
(m, 12H)
8.86
8.57-8.59
(d, 6H)
-2.71
(s, 6H)
-2.79
2
(m, 6H)
8.72-8.73
(d, 2H)
8.22-8.23
(d, 8H)
(m, 6H)
8.33-8.35
(d, 2H)
7.74-7.76
(m, 12H)
(m, 12H)
8.20-8.22
(d, 6H)
(m, 27H)
8.05-8.07
(d, 2H)
H2TPCNPP
ZnTPP
(s, 2H)
(s, 8H)
10