[Fe(bpy)3]2+-based porous organic polymers with boosted photocatalytic activity for recyclable organic transformations

Article abstract of DOI:10.1039/d0ta12267j

Three rigid metal porous organic polymers (POPs) based on an iron(ii) complex are prepared from the condensation reactions of an octahedral [Fe(bpy)₃]²⁺-cored hexaaldehyde and three rod-like aromatic diamines. The POPs have been studied as the first series of earth-abundant metal complex-connected photocatalysts for heterogeneous visible light-driven oxidation of benzyl halides and enantioselective α-alkylation of aldehydes. Both yields and enantioselectivities of the reactions catalyzed by one of the POPs, which possesses the largest porosity, rival or even surpass those of the reactions homogeneously catalyzed by control [Fe(bpy)₃]²⁺complexes. Moreover, POP catalysts are highly stable and exhibit a considerable activity after recycling 10 times.

Full text of DOI:10.1039/d0ta12267j

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[Fe(bpy)3]2+-based porous organic polymers with
boosted photocatalytic activity for recyclable
organic transformations†
Cite this: J. Mater. Chem. A, 2021, 9,
6361
a
Hong-Kun Liu,a Yi-Fei Lei,a Peng-Ju Tian,b Hui Wang,a Xin Zhao,b Zhan-Ting Li
*
a
*
and Dan-Wei Zhang
Three rigid metal porous organic polymers (POPs) based on an iron(II) complex are prepared from the
condensation reactions of an octahedral [Fe(bpy)3]2+-cored hexaaldehyde and three rod-like aromatic
diamines. The POPs have been studied as the first series of earth-abundant metal complex-connected
photocatalysts for heterogeneous visible light-driven oxidation of benzyl halides and enantioselective a-
alkylation of aldehydes. Both yields and enantioselectivities of the reactions catalyzed by one of the
POPs, which possesses the largest porosity, rival or even surpass those of the reactions homogeneously
catalyzed by control [Fe(bpy)3]2+ complexes. Moreover, POP catalysts are highly stable and exhibit
a considerable activity after recycling 10 times.
Received 18th December 2020
Accepted 1st February 2021
DOI: 10.1039/d0ta12267j
rsc.li/materials-a
(bpy: 2,20-bipyridine) can enable photocatalytic enantioselective
alkylation of aldehydes with various a-bromocarbonyl
compounds.33 With [Fe(phen)3]2+ (phen: 1,10-phenanthroline)
Introduction
In the past two decades, visible light photoredox catalysis of
organic transformations has received great attention due to its
mild reaction conditions and the potential of harvesting solar
energy for chemical transformations.1–12 Currently, there are
two major kinds of photosensitizers, i.e., transition metal
complexes and organic dyes,13–20 which can efficiently mediate
single-electron transfer processes with organic substrates upon
photoexcitation with visible light. In the rst category,
complexes of ruthenium and iridium with various pyridine
ligands have been most widely investigated for various organic
transformations.1–13 However, both metals are precious and
have very low abundance (ꢀ10ꢁ7) in Earth's crust. Thus,
chemists have a long-standing interest in photoactive molecular
complexes made from abundant elements,21–29 particularly the
iron element that has very high abundance (4.7%) in the crust
and is much less expensive,30–32 even though iron complexes
typically have a short-lived excited state that does not favor the
initiation of electron transfer-mediated organic reactions. In
2015, Cozzi, Ceroni and co-workers reported that [Fe(bpy)3]2+
as a photocatalyst, Collins and co-workers realized the oxidative
cyclization of triaryl and diarylamines into their corresponding
carbazoles,34 whereas Kang and co-workers achieved the cyclo-
addition reactions of alkene radical cations with diazo
compounds to afford cyclopropanes and single-electron oxida-
tion and a-deprotonation of tertiary anilines to yield a-amino-
alkyl radicals, which couple with electrophilic reagents to form
tetrahydroquinolines.35,36 All the reactions are carried out in
a homogeneous manner. Further development of heteroge-
neous methodologies for recyclable utilization of catalysts
would not only lower the costs of both the metal and ligand, but
would also enhance the environmentally benign feature of iron-
based catalysts. To the best of our knowledge, such methodol-
ogies have not been reported for complex catalysts made from
iron and other earth-abundant transition metals.
Porous organic polymers (POPs) represent a class of highly
cross-linked and synthetically accessible conjugated materials
with inherent porosity that enables a variety of functions or
applications.37–42 One of the most promising applications of
POPs has been the development of recyclable, heterogeneous
catalysts for efficient organic transformations.43–45 In this cate-
gory, rigid, well-dened ruthenium and iridium complexes have
been incorporated into or appended to the frameworks of POPs
for the catalysis of a large number of organic reactions under
visible-light irradiation.46–57 Replacement of the precious metal
complexes with iron complexes may further reduce the cost of
the heterogeneous catalysts by maintaining the recyclability of
the corresponding POPs. We herein describe the synthesis of
three highly stable [Fe(bpy)3]2+(bpy: 2,20-bipyridine)-based,
aDepartment of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and
Innovative Materials, Fudan University, 2205 Songhu Lu, Shanghai 200438, China.
E-mail: ztli@fudan.edu.cn; zhangdw@fudan.edu.cn
bKey Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional
Molecules, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
345 Lingling Lu, 200032, China
† Electronic supplementary information (ESI) available: Synthesis and
characterization of new compounds and reaction products, TGA and SEM
images, the EDS prole, and FT-IR, uorescence and UV-vis spectra. CCDC
2040861. For ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/d0ta12267j
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noble-metal-free porous organic polymers (Fe-POP-1–3) from
Results and discussion
a
[Fe(bpy)3]2+-derived hex-
the condensation reaction of
aaldehyde and three rod-like aromatic diamines. We demon-
strate that the three coordination polymers could be applied to
visible-light-driven oxidation of benzyl halides and enantiose-
lective a-alkylation of aldehydes with high recyclability of up to
ten times. In particular, the [Fe(bpy)3]2+ unit in heterogeneous
Fe-POP-1, which possesses the largest pore aperture, exhibits
comparable or even higher catalytic activity for both reactions
as compared with homogeneous control complexes.
The synthetic routes for Fe-POP-1–3 are shown in Scheme 1. The
key intermediate, iron(II) complex hexaaldehyde 2a, was
synthesized from the reaction of 1a with ferrous chloride in
deionized water. Subsequently, iron(II) complex 2a was treated
with 3a–c in the mixture of 1,4-dioxane/mesitylene or 1,2-
ꢂ
dichlorobenzene/isopropanol at 120 C for 3 days to afford Fe-
POP-1–3, respectively. As control complexes, iron(II) complexes
2b (Fe(bpy)3(PF6)2) and 2c were also prepared from the reaction
of ferrous chloride with bipyridine ligand 1b or 1c. Single
crystals were obtained by diffusing diethyl ether into the satu-
rated solution of 2a in acetonitrile. Its X-ray diffraction structure
conrmed the octahedral feature of the complex (Fig. 1). Thus,
its condensation with rod-like monomers 3a–c was expected to
afford rigid [Fe(bpy)3]2+-connected POPs Fe-POP-1–3, which
could lead to a short-range pcu topological structure through an
ideal condensation process. All the polymers were insoluble in
common solvents including water, dimethyl sulfoxide (DMSO),
N,N-dimethylformamide (DMF), acetone and acetonitrile. In
contrast, control complexes 2b and 2c were highly soluble in the
above organic solvents. Thermogravimetric analyses (TGA)
revealed that polymers Fe-POP-1–3 were stable up to 400 ꢂC
(15% weight loss) (Fig. S1, ESI†).
Fourier transform infrared spectroscopy of Fe-POP-1–3 did
not exhibit the absorption of the C]O stretching vibration of
compound 2a at 1707 cmꢁ1 or the absorption of the N–H
stretching vibration around 3350 cmꢁ1 of compounds 3a–c
(Fig. S2–S4, ESI†), respectively, which indicated that the
monomers were consumed nearly completely in the condensa-
tion reactions. The solid-state UV-vis spectra of the three POPs
(Fig. S5, ESI†) displayed a wide range of UV-vis absorptions,
whereas the uorescence spectra exhibited two emissions cen-
tred around 486 and 530 nm (Fig. S6, ESI†), suggesting
tremendous photo-activity and potential photocatalysis. Scan-
ning electron microscope (SEM) images showed the formation
of amorphous structures (Fig. S7–S9, ESI†), and powder X-ray
diffraction (PXRD) proles did not exhibit assignable peaks,
which also suggested the amorphous feature (Fig. S10, ESI†).
Energy dispersive X-ray spectroscopy (EDS) supported the exis-
tence of Fe, C, N, P, and F elements for all three polymers
(Fig. S11–S13, ESI†), whereas their X-ray photoelectron spec-
troscopic (XPS) proles further conrmed the composition of
the above elements (Fig. 2). The binding energy of 2p3/2 of the Fe
element of the three polymers (708.3, 709.8, and 709.4 eV,
respectively) was all close to the value of FeO (709.1–709.6 eV)
(Fig. 2b), but far from that of Fe2O3 (711.3–711.9 eV), indicating
that no valence change occurred for the Fe element during the
polymerization. The proles also showed the peak of the O
element, which could be attributed to solvent molecule
adsorption by the materials and/or the oxidation of partial Fe2+
complexes to Fe3+ complexes.46,55,56 Inductively coupled plasma
atomic emission spectrometric (ICP-AES) analysis revealed that
the three polymers had an Fe content of 4.47%, 3.90%, or
3.29%, which was close to their respective calculated values
(4.66%, 3.92%, and 3.38%) aer quantitative condensation,
Scheme 1 The synthesis of complexes 2a–c and POPs Fe-POP-1–3.
Fig. 1 Crystal structure of complex 2a.
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Emmett–Teller (BET) surface area were determined to be 39, 49
and 65 m2 gꢁ1, respectively (Fig. 3). The existence of the optical
ꢁ
isomers of the [Fe(bpy)3]2+ complexes and PF6 counterions
may account for the low or modest surface area, as revealed for
ruthenium or iridium complex-based POPs.46,52,55 The surface
area increased with the elongation of the linkers in the poly-
mers, which implied that Fe-POP-3 might exhibit the highest
catalytic efficiency.
The potential of Fe-POP-1–3 for heterogeneous visible-light-
driven photocatalysis of organic transformations was then
explored. The oxidation reaction of benzyl halides, which
affords the corresponding phenyl carbonyl compounds, was
investigated rstly. Previously, Jiao and co-workers realized this
oxidation process homogeneously in N,N-dimethyl acetamide
(DMAc) with Ru(bpy)3Cl2 as a photosensitizer.58 With air O2 as
the oxidant, this reaction provides a one-step method of trans-
forming benzyl halides to the corresponding phenyl carbonyl
compounds. Cheng and Zhang and co-workers also utilized
metal–organic framework-loaded [Ru(bpy)3]Cl2 to photocatalyze
this reaction heterogeneously.59 We rst studied the oxidation
of compound 4a to produce 5a with Fe-POP-1–3 as heteroge-
neous photocatalysts under the conditions used with [Ru(bpy)3]
Cl2 as a homogeneous photocatalyst.58 The results are summa-
rized in Table 1. All three POPs catalyzed the reaction and 5a
was obtained in 63%, 74% or 90% yield (entries 1–3), respec-
tively. Under the identical conditions, controls 2b and 2c also
catalyzed the reaction homogeneously to yield 5a in 53% or 64%
yield (entries 4 and 5). Given the amorphous nature of the POPs,
Fig. 2 (a) The XPS survey spectra and (b) the Fe 2p spectra of polymers
Fe-POP-1–3.
Table 1 Optimization of the photocatalytic oxidation reaction of
benzyl halide 4aa
which also supported that the complex did not decompose
during polymerization and thus no Fe loss occurred due to the
decomposition of the complex.
The permanent porosity of Fe-POP-1–3 was investigated by
nitrogen sorption measurements at 77 K. Their Brunauer–
Entry
Catalyst (1.0 mol%)
Solvent
Yieldb (%)
1
2
Fe-POP-1
Fe-POP-2
Fe-POP-3
2b
2c
—
Fe-POP-3
Fe-POP-3
Fe-POP-3
Fe-POP-3
Fe-POP-3
Fe-POP-3
2c
DMAc
DMAc
DMAc
DMAc
DMAc
DMAc
DMAc
DMAc
DMF
63
74
90
53
64
16
64
79
65
29
41
39
34
28
3c
4c
5c
6d
7e
8f
9
10
11
12
13
14
MeCN
iPrOH
THF
iPrOH
THF
2c
a
Reaction conditions: 4a (1.0 mmol), [Fe] (0.01 mmol), cocatalyst 4-
methoxypyridine (0.2 mmol), Li2CO3 (1.0 mmol), solvent (5 mL) under
air at 25 ꢂC, irradiation with two 34 W blue LED lights at a distance of
b
8 cm for 24 h. Yield determined by GC using n-dodecane as the
c
d
internal standard. Average value of the three reactions. Without
e
Fig. 3 N2 adsorption and desorption isotherms of polymers Fe-POP-
1–3 at 77 K.
the addition of the metal catalyst. 15 mol% 4-methoxypyridine was
used. f Na2CO3 used as the base.
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Scheme 2 Proposed mechanism for the photocatalytic oxidation of
4a to 5a with polymers Fe-POP-1–3 as heterogeneous catalysts.
it is reasonable to assume that not all of the [Fe(bpy)3]Cl2 units
of the POPs could be reached by the substrate molecules. Thus,
the fact that Fe-POP-2 and Fe-POP-3 realized higher yields of 5a
than 2b or 2c should be attributed to the cooperative effect of
the [Fe(bpy)3]Cl2 units, which, in an ideal structure, could form
a cubic cage to facilitate the oxidation of the substrate. In the
absence of the catalysts, 5a was obtained in 16% yield (entry 6).
Visible light irradiation was indispensable for the reaction,
because removing the lamps during the reaction nearly
completely stopped the reaction (Fig. S14, ESI†). As Fe-POP-3
exhibited obviously higher photocatalytic activity, we further
studied the effect of different reaction conditions on the reac-
tion of this POP. It was revealed that decreasing the amount of
4-methoxypyridine cocatalyst caused signicant reduction of
the yield (entry 7), whereas using Na2CO3 as a base also led to
a slight decline of the yield (entry 8). The oxidation reaction
could also take place in DMF, MeCN, iso-PrOH or THF (entries
9–12), but the yield of 5a decreased signicantly. Although the
yields were all lowered, with iso-PrOH or THF as solvent, Fe-
POP-3 could also afford a higher yield of 5a than control
complex 2c, which was insoluble in the two solvents and thus
should function in a heterogeneous manner (entries 11–14),
which further illustrated the importance of the porosity of the
POPs in boosting their catalytic activity. ICP-AES experiments
revealed that the contents of Ir, Ru, Pd or Rh in Fe-POPs were
less than 0.02 ppm, which supported that the catalysis was not
caused by these rare transition metals possibly present in the
POPs. We thus proposed that this heterogeneous photocatalytic
oxidation of 4a to 5a proceeded through the mechanism
established for the same reaction with [Ru(bpy)3]Cl2 as
a homogeneous photocatalyst (Scheme 2).57
Fig. 4 (a) Recyclability of Fe-POP-3 in the oxidation reaction of 4a (2.0
mmol) to form 5a. (b) Recyclability of Fe-POP-3 in the reaction of 6a
and 7a to form 9a.
The recyclability of Fe-POP-3 was also investigated for the
above oxidation reaction. The solid catalyst was isolated by
centrifugation, washed with deionized water and DMAc and
then reused in a fresh reaction solution. The reaction yield of 5a
gradually decreased (Fig. 4a). However, aer ten cycles, 5a was
Scheme 3 Substrate scope of Fe-POP-3 catalyzed oxidation of benzyl
halides 4a–h to form the corresponding phenyl carbonyl compounds
5a–h. The yield represented is the isolated yield.
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still obtained in 62% yield, which well reected the high coupling product 9a was produced in 23%, 53% and 85% yields
stability of the catalyst. The gradual decrease of the yield might (entries 1–3, Table 2), respectively. These results were consistent
be caused by the loss and decomposition of the catalyst as well with those of the above oxidation reaction, showing that large
as metal leaching during the process.
porosity of the POPs favored the photocatalytic process. Further
The above reaction conditions (Table 1) were then applied to increase of Fe-POP-3 did not improve the yield of 9a, whereas in
a series of 2-bromo-2-phenylacetates (4b–e) (Scheme 3). Fe-POP- the presence of 0.5 mol% ([Fe]) amount of Fe-POP-3, 9a could be
3 was chosen as the photocatalyst because of its highest pho- obtained in 76% yield (entries 4 and 5). Again, we found that
tocatalytic activity. All the reactions gave rise to the corre- visible light irradiation was also indispensable for this reaction
sponding ketone derivatives (5b–e) in high to excellent yields (Fig. S15, ESI†). The photocatalyst also worked well in THF to
(79–93%), which showed high tolerance of the ester groups as allow for the generation of 9a in 80% yield (entry 6), but in iso-
well as the substituents on the benzene ring. The above reaction propanol, the yield of 9a was substantially lowered (entry 7).
conditions could also be applied to 2-bromo-1,2-diphenylethan- Control photocatalyst 2b also efficiently catalyzed the reaction
1-one 4f, which gave rise to benzil 5f in 96% yield. Under the in DMF to afford 9a in 83% yield in a heterogeneous manner
identical reaction conditions, 9-bromouorene 4g was also (entry 8). Another control 2c was also soluble in DMF, but did
oxidized to afford uorenone 5g in 88% yield.
not exhibit photocatalytic activity (entry 9). Thus, once again,
Visible-light-driven enantioselective a-alkylation of alde- the heterogeneous photocatalyst Fe-POP-3 can realize a catalytic
hydes represents a mild and efficient transformation for activity that rivals or even surpasses that of a homogeneous one.
asymmetric C–C bond formation. This reaction was rst re- With iso-propanol as solvent, in which both 2b and 2c were
ported by Nicewicz and MacMillan using Ru(bpy)3Cl2 insoluble, the two photocatalysts allowed the formation of 9a in
(0.5 mol%) as a homogeneous photocatalyst and the MacMillan 21% and 7% yields (entries 10 and 11), respectively.
catalyst chiral imidazolidinone 8 as a chiral-organocatalyst.60
From the reaction of 6a and 7a, 9a was obtained with high
Ceroni and Cozzi described that catalytic amounts (2.5 mol%) enantioselectivity (95% ee), which was comparable with that
of the [Fe(bpy)3]Br2 complex can help realize this reaction to (93% ee) obtained under the homogeneous catalysis of
produce the corresponding products with comparable yields Fe(bpy)3Br2.33 We then applied the above optimized reaction
and enantioselectivities.33 We thus further explored the capa- conditions to the reactions between aldehydes 6a and 6b and 2-
bility of Fe-POP-1–3 as heterogeneous photocatalysts for this
transformation. We rst studied the reaction of 6a and 7a in the
presence of catalytic amounts of Fe-POP-1–3 ([Fe]: 1 mol%), 8
(20 mol%) and 2,6-lutidine (2 equiv.) in DMF (Table 2). The
Table 2 Optimization of the photocatalytic enantioselective reaction
of aldehyde 6a and bromide 7a to afford 9a
Entry
Catalyst (mol%)
Solvent
Yielda (%)
1
2
3
4
5
6
7
8
Fe-POP-1 (1.0)
Fe-POP-2 (1.0)
Fe-POP-3 (1.0)
Fe-POP-3 (2.5)
Fe-POP-3 (0.5)
Fe-POP-3 (1.0)
Fe-POP-3 (1.0)
2b (1.0)
DMF
DMF
DMF
DMF
DMF
THF
23
53
85
82
76
80
41
83
<1
21
7
iPrOH
DMF
DMF
iPrOH
iPrOH
Scheme 4 Substrate scope of Fe-POP-3-catalyzed enantioselective
a-alkylation of aldehydes 6a–b for the formation of the corresponding
products 9a–h. The yield represents the isolated one. The reactions
were carried out on the scale of 1 mmol of 6 (7: (0.5 mmol) in DMF (1
mL)).
9
10
11
2c (1.0)
2b (1.0)
2c (1.0)
a
Yield determined by GC using n-dodecane as the internal standard.
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bromoacetophenones 7b–d (Scheme 4). All the reactions affor-
ded the corresponding coupling products 9b–h in good to
excellent yields (77–86%) and ee values (89–93%), which were
comparable to or even higher than those of the identical reac-
tion catalyzed homogeneously by Fe(bpy)3Br2.33 Moreover, the
introduction of electron-donating (MeO) or withdrawing (Cl)
groups on the benzene ring did not have great inuence on both
yield and enantioselectivity, which reected a good tolerance of
the variety of substrates. The mechanism for the homogeneous
photocatalysis of the above reactions by Fe(bpy)3Br2 has been
established by Ceroni and Cozzi.33 It is reasonable to propose
that the present heterogeneous photocatalysis of these reac-
tions should proceed through an identical mechanism
(Fig. S16, ESI†).
2 J. M. R. Narayanam and C. R. J. Stephenson, Chem. Soc. Rev.,
2011, 40, 102–113.
3 D. M. Schultz and T. P. Yoon, Science, 2014, 343, 985.
4 J. Xuan and W.-J. Xiao, Angew. Chem., Int. Ed., 2012, 51, 6828–
6838.
5 R. Brimioulle, D. Lenhart, M. M. Maturi and T. Bach, Angew.
Chem., Int. Ed., 2015, 54, 3872–3890.
6 X. Huang and E. Meggers, Acc. Chem. Res., 2019, 52, 833–847.
7 H. Zhang and S. Yu, Acta Chim. Sin., 2019, 77, 832–840.
8 X.-Y. Yu, Q.-Q. Zhao, J. Chen, W.-J. Xiao and J.-R. Chen, Acc.
Chem. Res., 2020, 53, 1066–1083.
9 H.-H. Zhang, H. Chen, C.-J. Zhu and S.-Y. Yu, Sci. China:
Chem., 2020, 63, 637–647.
10 S. K. Pagire, T. Foell and O. Reiser, Acc. Chem. Res., 2020, 53,
782–791.
Given the high yield and enantioselectivity of 9a from the
reaction of 6a and 7a under the heterogeneous photocatalysis of 11 J. M. Lee and A. I. Cooper, Chem. Rev., 2020, 120, 2171–2214.
Fe-POP-1, we further studied the recyclability of Fe-POP-1 for 12 P. Xu, W.-P. Li, J. Xie and C.-J. Zhu, Acc. Chem. Res., 2018, 51,
this transformation. Aer 10 times of repeated use, Fe-POP-1
484–495.
still enabled the production of 9a in 62% yield, even though the 13 F. Tepl´y, Collect. Czech. Chem. Commun., 2011, 76, 859–917.
yield gradually decreased with the repeated use of the catalyst 14 D. Ravelli and M. Fagnoni, ChemCatChem, 2012, 4, 169–171.
(Fig. 4b). Notably, even aer 10 times recycling, the ee value was 15 M. Majek and A. J. Wangelin, Acc. Chem. Res., 2016, 49, 2316–
just decreased slightly from the original 95% to 91%. This result
clearly reected the high stability of the heterogeneous photo- 16 M. K. Bogdos, E. Pinard and J. A. Murphy, Beilstein J. Org.
catalyst and also suggested that the decrease of the yield was Chem., 2018, 14, 2035–2064.
2327.
caused mainly by the loss of the catalyst during the processes. 17 R. Li, J. Byun, W. Huang, C. Ayed, L. Wang and K. A. I. Zhang,
ACS Catal., 2018, 8, 4735–4750.
18 Y. Markushyna, C. A. Smith and A. Savateev, Eur. J. Org.
Conclusions
Chem., 2020, 2020, 1294–1309.
We have demonstrated a convenient strategy for the prepara- 19 B. Chen, L.-Z. Wu and C. H. Tung, Acc. Chem. Res., 2018, 51,
tion of Fe(bpy)3-based porous organic polymers. The new earth-
2512–2523.
abundant metal complex-derived materials work well as 20 Q. Liu and L.-Z. Wu, Natl. Sci. Rev., 2017, 4, 359–380.
heterogeneous photocatalysts for recyclable organic trans- 21 C. B. Larsen and O. S. Wenger, Chem.–Eur. J., 2018, 24, 2039–
formations. For the two investigated reactions, the heteroge-
2058.
neous photocatalysts exhibited high activity that rivals or even 22 J. K. McCusker, Science, 2019, 363, 484–488.
surpasses that of homogeneous control photocatalysts. More- 23 J.-L. Dai, W.-L. Liu and Q. Liu, Acta Chim. Sin., 2019, 77, 911–
over, the enantioselectivity of the coupling reactions mediated
by the chiral co-organocatalyst also rivals that obtained under 24 T. Mandal, S. Das and S. De Sarkar, Adv. Synth. Catal., 2019,
the homogeneous reaction conditions, which illustrates the 361, 3200–3209.
high stability of the new kind of metal complex-derived porous 25 A. Hossain, A. Bhattacharyya and O. Reiser, Science, 2019,
polymer. This work opens new perspectives for the use of other 364, eaav9713.
earth-abundant metal complexes for efficient heterogeneous 26 W.-M. Cheng and R. Shang, ACS Catal., 2020, 10, 9170–9196.
915.
photocatalysis of organic transformations.
27 B. M. Hockin, C. Li, N. Robertson and E. Zysman-Colman,
Catal. Sci. Technol., 2019, 9, 889–915.
28 O. S. Wenger, J. Am. Chem. Soc., 2018, 140, 13522–13533.
29 M. D. Woodhouse and J. K. McCusker, J. Am. Chem. Soc.,
2020, 142, 16229–16233.
Conflicts of interest
There are no conicts to declare.
30 O. S. Wenger, Chem.–Eur. J., 2019, 25, 6043–6052.
31 W.-J. Zhou, X.-D. Wu, M. Miao, Z.-H. Wang, L. Chen,
S.-Y. Shan, G.-M. Cao and D.-G. Yu, Chem.–Eur. J., 2020, 26,
15052–15064.
Acknowledgements
We are grateful to The National Natural Science Foundation of
China (No. 21921003, 21890730 and 21890732) for nancial 32 J.-H. Ye, M. Miao, H. Huang, S.-S. Yan, Z.-B. Yin, W.-J. Zhou
support of this work.
and D.-G. Yu, Angew. Chem., Int. Ed., 2017, 56, 15416–15420.
33 A. Gualandi, M. Marchini, L. Mengozzi, M. Natali,
M. Lucarini, P. Ceroni and P. G. Cozzi, ACS Catal., 2015, 5,
5927–5931.
Notes and references
1 C. K. Prier, D. A. Rankic and D. W. C. MacMillan, Chem. Rev., 34 S. Parisien-Collette, A. C. Hernandez-Perez and S. K. Collins,
2013, 113, 5322–5363.
Org. Lett., 2016, 18, 4994–4997.
6366 | J. Mater. Chem. A, 2021, 9, 6361–6367
This journal is © The Royal Society of Chemistry 2021

View Article Online
Paper
Journal of Materials Chemistry A
35 Y. H. Cho, J. H. Kim, H. An, K.-H. Ahn and E. J. Kang, Adv. 48 Y.-P. Wu, M. Yan, Z.-Z. Gao, J.-L. Hou, H. Wang, D.-W. Zhang
Synth. Catal., 2020, 362, 2183–2188. and Z.-T. Li, Chin. Chem. Lett., 2019, 30, 1383–1386.
36 J. Y. Hwang, A. Y. Ji, S. H. Lee and E. J. Kang, Org. Lett., 2020, 49 X.-J. Yang, T. Liang, J.-X. Sun, M. J. Zaworotko, Y. Chen,
22, 16–21. P. Cheng and Z.-J. Zhang, ACS Catal., 2019, 9, 7486–7493.
37 Q. Sun, B. Aguila, Y. Song and S. Ma, Acc. Chem. Res., 2020, 50 Y. Luo, Z.-Y. Xu, H. Wang, X.-W. Sun, Z.-T. Li and
53, 812–821. D.-W. Zhang, ACS Macro Lett., 2020, 9, 90–95.
38 T.-X. Wang, H.-P. Liang, D. A. Anito, X. Ding and B.-H. Han, J. 51 Z.-G. Xie, C. Wang, K. E. deKra and W.-B. Lin, J. Am. Chem.
Mater. Chem. A, 2020, 8, 7003–7034. Soc., 2011, 133, 2056–2059.
39 T. Zhang, G. Xing, W. Chen and L. Chen, Mater. Chem. Front., 52 H.-P. Liang, Q. Chen and B.-H. Han, ACS Catal., 2018, 8,
2020, 4, 332–353. 5313–5322.
40 C. Xu, W.-J. Zhang, J.-T. Tang, C.-Y. Pan and G.-P. Yu, Front. 53 C. Wang, Z.-G. Xie, K. E. deKra and W.-B. Lin, ACS Appl.
Chem., 2018, 6, 592. Mater. Interfaces, 2012, 4, 2288–2294.
41 Y. Byun, S. H. Je, S. N. Talapaneni and A. Coskun, Chem.–Eur. 54 Z.-Z. Gao, Y.-Y. Xu, Z.-K. Wang, H. Wang, D.-W. Zhang and
J., 2019, 25, 10262–10283. Z.-T. Li, ACS Appl. Polym. Mater., 2020, 2(11), 4885–4892.
42 R.-R. Liang and X. Zhao, Org. Chem. Front., 2018, 5, 3341– 55 Z.-Y. Xu, Y. Luo, D.-W. Zhang, H. Wang, X.-W. Sun and
3356. Z.-T. Li, Green Chem., 2020, 22, 136–143.
43 P. Kaur, J. T. Hupp and S. T. Nguyen, ACS Catal., 2011, 1, 56 R. Dorta, R. Goikhman and D. Milstein, Organometallics,
819–835. 2003, 22, 2806–2809.
44 Y.-G. Zhang and S. N. Riduan, Chem. Soc. Rev., 2012, 41, 57 X.-F. Li, X.-B. Liu, J.-Y. Chao, Z.-K. Wang, F.-U. Rahman,
2083–2094.
H. Wang, D.-W. Zhang, Y. Liu and Z.-T. Li, Sci. China:
Chem., 2019, 62, 1634–1638.
58 Y.-J. Su, L.-R. Zhang and N. Jiao, Org. Lett., 2011, 13, 2168–
2171.
59 X.-J. Yang, T. Liang, J.-X. Sun, M. J. Zaworotko, Y. Chen,
P. Cheng and Z.-J. Zhang, ACS Catal., 2019, 9, 7486–7493.
60 D. A. Nicewicz and D. W. C. Macmillan, Science, 2008, 322,
77–80.
45 B. Yang, H. Wang, D.-W. Zhang and Z.-T. Li, Chin. J. Chem.,
2020, 38, 970–980.
46 J.-L. Wang, C. Wang, K. E. deKra and W.-B. Lin, ACS Catal.,
2012, 2, 417–424.
47 L.-Y. Li, C.-Y. Cui, W.-Y. Su, Y.-X. Wang and R.-H. Wang,
Nano Res., 2016, 9, 779–786.
This journal is © The Royal Society of Chemistry 2021
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