Structural design of Mn-metal-organic frameworks toward highly efficient solvent-free cycloaddition of CO2

Heterogeneous Catalysts for Water Splitting and CO Fixation

Article

Structural Design of Mn-Metal−Organic Frameworks toward Highly

Eﬃcient Solvent-Free Cycloaddition of CO

Published as part of a Crystal Growth and Design virtual special issue on Coordination Polymers as

Haonan Lin, Cheng-Hua Deng, Xiaohang Qiu, Xiao Liu,* Jian-Gong Ma, and Peng Cheng*

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sı Supporting Information

ABSTRACT: Three new manganese-based metal−organic frame-

works (Mn-MOFs), [Mn(L)(H O)] ·2DMA (1),

[

Mn (L) (H O) ]·2DMA (2), and [Mn (L) (DMF) (H O)]·

2 2 2 3 2 2 2 2

DMF (3), have been synthesized with the ligand H L (N-

phenyl-N′-phenylbicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxdii-

mide dicarboxylic acid). The secondary building units (SBUs) of

the Mn-MOFs are controlled by changing the anions of the

manganese salts, and the structures are modiﬁed from two-fold

interpenetrating to non-interpenetrating by adjusting the mixed

solvent systems. Along with the structural modiﬁcation of the Mn-

MOFs, we optimized their catalytic activities for the reaction of

CO and epoxides toward cyclic carbonates. Both the activity and

reusability of the Mn-MOFs are successfully improved in the solvent-free cycloaddition of CO with various epoxides under the mild

conditions of atmospheric pressure and 70 °C.

. INTRODUCTION

diﬃculty of separation is a disadvantage of homogeneous

catalysts. Heterogeneous catalysts, such as binuclear molybde-

Since the industrial revolution, carbon stored in the stratum

such as coal, oil, and natural gas has been overutilized as fossil

fuels, and the overexploitation of forests by humans has caused

the CO content in the atmosphere to rise sharply. On the

one hand, CO is the main greenhouse gas, which is leading to

more serious global warming. On the other hand, CO is safe,

cheap, and renewable and the most abundant C1 resource.

Therefore, utilization of CO through chemical means can not

only reduce its impact on the environment but also beneﬁt the

production of high value-added chemicals. So far, the chemical

use of CO mainly includes the reduction of CO by H to

produce methanol, the reaction of CO and CH to produce

synthesis gas, the reaction of CO with methanol to synthesize

num alkoxides, clusters, metal-salen, metal−organic

frameworks (MOFs), and polyoxometalates (POMs),

have thus been developed. Because of the characteristics of

high porosity and high speciﬁc surface area, MOFs can

automatically capture CO and catalyze the conversion

21−26

eﬃciently.

With the abundant valency and various

potential active sites, manganese-based metal−organic frame-

works (Mn-MOFs) have been considered as excellent catalysts

for this reaction. However, the structure−activity relationship

of Mn-MOFs in such a reaction has been rarely investigated,

and the conversion conditions for a large part of Mn-MOFs are

not optimized.

In this work, we synthesized three new Mn-MOFs

dimethyl carbonate (DMC), and the carboxylation of CO

and alkylene oxide to synthesize cyclic carbonate.

−11

[Mn(L)(H O)]·2DMA (1), [Mn (L) (H O) ]·2DMA (2),

and [Mn (L) (DMF) (H O)]·3DMF (3) with the ligand

As an important raw material, cyclic carbonate has been

H L (N-phenyl-N′-phenylbicyclo[2.2.2]oct-7-ene-2,3,5,6-tetra-

widely used as a polar solvent, fuel additive, polymer precursor,

and electrolyte solvent in lithium batteries.

12,13

carboxdiimide dicarboxylic acid) subsequently (Scheme 1).

The traditional

synthesis of cyclic carbonate usually requires toxic reagents,

such as phosgene and CO, and pollutant byproducts such as

hydrogen chloride are produced. Therefore, the synthesis of

Received: January 12, 2021

Revised: May 19, 2021

Published: May 26, 2021

cyclic carbonate by CO and alkylene oxide, which is easy to

obtain, renewable, and environmentally friendly, has become

an attractive procedure. Homogeneous catalysts, such as ionic

liquids, are generally eﬀective for this reaction, but the

2021 American Chemical Society

Cryst. Growth Des. 2021, 21, 3728−3735

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Scheme 1. Synthesis Diagrams for 1−3

The secondary building units (SBUs) of Mn-MOFs were

changed from the paddle-wheel unit (1) to the dinuclear Mn

node with more potential metal sites (2) via adjusting anions

of manganese salts. The two-fold interpenetrating conforma-

tions of 1 and 2 were further modiﬁed into the non-

interpenetrating conformation of 3 by adjusting the mixed

solvent systems. Along with the structural modiﬁcation, the

stability, activity, and reusability of the Mn-MOFs were

signiﬁcantly improved in the solvent-free cycloaddition of

obtained. Yield: ca. 33.78% (based on H

L). Anal. Calcd. (%) for

C H MnN O (1): C 55.82, H 4.96, N 7.66; found: C 54.98, H

34 36

.65, N 7.06; After drying in a vacuum, Anal. Calcd. (%) for

C H MnN O : C 55.75, H 3.29, N 4.9; found: C 56.09, H 3.45, N

.28.

Synthesis of [Mn (L) (H O) ]·2DMA (2). H L (0.2 mmol, 0.0972

g) and MnCl ·4H O (0.1 mmol, 0.0198 g) were dissolved in 4 mL of

N,N-dimethylacetamide (DMA) and 2 mL of n-octanol, then sealed in

a 20 mL screw-capped vial, and heated in an oven under 110 °C for 3

days. Then the mixture was washed three times by methanol and

dried at room temperature. Finally, colorless block crystals were

CO under the mild conditions of atmospheric pressure and 70

°C. Especially, the amount of cocatalyst was signiﬁcantly

obtained. Yield: ca. 31.32% (based on H

L). Anal. Calcd. (%) for

C H Mn N O (2): C 55.14, H 4.32, N 6.43; found: C 54.59, H

reduced, and the conversion of cyclohexene oxide was

dramatically increased over the other known heterogeneous

catalysts.

60 56

.70, N 6.02; After drying in a vacuum, Anal. Calcd. (%) for

C H Mn N O : C 55.75, H 3.29, N 4.97; found: C 55.71, H 3.32,

N 5.01.

Synthesis of [Mn (L) (DMF) (H O)]·3DMF (3). H L (0.3 mmol,

. EXPERIMENTAL SECTION

0.1458 g) and MnCl ·4H O (0.2 mmol, 0.0396 g) were dissolved in 2

2 2

mL of acetonitrile and 4 mL of N,N-dimethylformamide (DMF), then

added into a 20 mL screw-capped vial, and heated in an oven under

Materials and Methods. All the reagents were procured from a

reagent company and were used directly without further puriﬁcation.

IR spectra were recorded on a Bruker Alpha spectrometer. Elemental

analyses were carried out on an Elementar vario EL CUBE

instrument. Powder X-ray diﬀraction (PXRD) was carried out using

an Ultima IV X-ray diﬀractometer. Thermal analysis was carried out

using a NETZSCH TG 209F3 device. Gas chromatography was

carried out using a GC 7900 instrument.

10 °C for 3 days. Then the mixture was washed three times by

methanol and dried at room temperature. Finally, colorless block

crystals were obtained. Yield: ca. 35.76% (based on H L). Anal. Calcd.

(

%) for C H Mn N O (3): C 55.04, H 4.72, N 8.62. found: C

67 69 2 9 22

4.91, H 4.68, N 8.16. After drying in a vacuum, Anal. Calcd. (%) for

C H Mn N O : C 56.04, H 3.87, N 6.76; found: C 55.03, H 3.94,

58 48

N 5.97.

Synthesis of H L. The ligand H L was synthesized by a modiﬁed

Crystallographic Data Collection and Reﬁnement. The data

collections of 1 and 3 were performed on a SuperNova, single source

at oﬀset/far, Eos diﬀractometer with graphite-monochromated Mo-

Kα radiation (λ = 0.71073 Å) with a CCD detector. The data of MOF

2 were collected on a XtaLAB Synergy diﬀractometer using Cu-Kα

radiation (λ = 1.54184 Å) with an Hypix6000HE detector. The

obtained diﬀraction data were reduced by the program suite

CrysAlispro (Rigaku Oxford Diﬀraction, CrysAlisPro Software system,

Rigaku Corporation, Oxford, UK, 2019). The structure determination

was operated in the OLEX2 graphical user interface. The structures

were solved using the SHELXT program using Intrinsic Phasing and

reﬁned using the SHELXL reﬁnement package with Least Squares

procedure. The mixture of 4-aminobenzoic acid (20 mmol, 2.74 g)

and bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride

(10 mmol, 2.48 g) was added into a 250 mL round-bottom ﬂask and

then 100 mL of acetic acid was poured into the ﬂask and reﬂuxed at

20 °C for 12 h. Then the mixture was removed from heat, cooled to

room temperature, washed three times by distilled water, and dried in

a vacuum at 100 °C. Finally, a white powder product was obtained

(

yield 92.8%, m.p. > 310 °C). H L was used for next procedures

without further puriﬁcation. Anal. Calcd. (%) for C H O N (H L):

C 63.85, H 4.02, N 5.78; found: C 64.20, H 3.73, N 5.76.

Synthesis of [Mn(L)(H O)]·2DMA (1). H L (0.2 mmol, 0.0972 g)

and Mn(OAc) ·4H O (0.1 mmol, 0.0245 g) were dissolved in 4 mL

29−31

of N,N-dimethylacetamide (DMA) and 2 mL of n-octanol, then

minimization.

All the thermal parameters of non-hydrogen atoms

sealed in a 20 mL screw-capped vial, and heated in an oven under 110

were reﬁned anisotropically. The H atoms of H O were generated

C for 3 days. Then the mixture was washed three times by methanol

and dried at room temperature. Finally, colorless block crystals were

from diﬀerent maps and reﬁned with isotropic temperature factors.

The H atoms of ligands were located geometrically. The unresolved

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Table 1. Crystal Data and Structure Reﬁnements for 1−3

compound

formula

C H MnN O

C H Mn N O

60 56

67 69

formula weight

temp, K

crystal system

space group

a (Å)

b (Å)

c (Å)

α (deg)

β (deg)

731.6

298.10(10)

1306.99

1462.18

131.0(7)

triclinic

100.00(10)

monoclinic

21.6275(4)

24.3471(4)

39.6245(7)

98.228(2)

20650.2(6)

orthorhombic

Ibam

11.7452(9)

20.0711(14)

36.576(2)

11.5426(6)

21.3222(13)

21.4823(9)

73.160(5)

85.511(4)

80.155(5)

4983.5(5)

γ (deg)

V (Å³)

8622.3(11)

0.859

D (g/cm )

μ (mm⁻¹)

0.729

2.339

0.877

0.304

0.340

R_i_n_t

0.1062

11930

4985

2280.0

0.0511

137759

61655

4640.0

1.028

0.1044

43530

22441

1360.0

reﬂections collected

independent reﬂections

F(000)

GOF on F²

0.885

0.846

R , wR [I > 2σ(I)]

0.0951, 0.2183

0.2044, 0.2865

0.48/−0.59

0.0648, 0.1790

0.0839, 0.1996

0.65/−0.74

0.0788,0.1365

0.1835,0.1824

0.39/−0.35

R , wR [all data]

max/min e⁻density (e Å⁻³

)

Figure 1. (a) Dinuclear SBUs of 1, 2, and 3; (b) the 2D lattice structures along the a-axis of 1, 2, and 3; and (c) the packing diagrams of 1, 2, and 3.

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Figure 2. (a) The coordination environment of 1, 2, and 3; (b) the coordination modes of H L in 1, 2, and 3. Green: Mn; red: O; blue: N; gray: C.

Hydrogen atoms are omitted for clarity.

electron densities were removed by PLATON/SQUEEZE. The

detailed data of the three crystals are recorded in Table 1.

Table 2. Temperature Gradient Experiments of the Solvent-

free CO Cycloaddition Catalyzed by 1−3

Catalytic Cycloaddition of CO with Epoxides toward the

Production of Cyclic Carbonates. Before the reaction, 1−3 were

activated by solvent exchange with CH Cl for 24 h and heated in a

vacuum for 12 h under 100 °C. In a typical CO coupling reaction

with epoxides, a mixture of catalyst (0.03 mmol based on Mn ) and

tetrabutylammonium bromide (TBAB, 0.1 mmol) was added into a

25 mL Schlenk ﬂask and activated under vacuum for several hours. A

CO -containing balloon was introduced into the Schlenk ﬂask, and

entry

catalyst

temp (°C)

time (h)

yield (%)

then styrene oxide (0.5 mL, 5 mmol) was added into the Schlenk ﬂask

through a syringe. Then, the mixture was stirred at the selected

temperature for 48 h. After the reaction was cooled down to room

temperature, the product was extracted with ethyl acetate and washed

with water to remove TBAB. The organic phase was dried with

none

anhydrous Na SO and subjected to gas chromatography to calculate

the yield. The products were analyzed and identiﬁed by gas

chromatography (GC, Techcomp GC7900, TM-5 capillary column,

0 m × 0.32 mm) with a ﬂame ionization detector (FID) and

nitrogen as the carrier gas.

. RESULTS AND DISCUSSION

>99

Crystal structure of [Mn(L)(H O)]·2DMA (1). The

synthesis routes of 1−3 are shown in Scheme 1. 1 was

synthesized by the reaction of Mn(OAc) with the ligand in a

mixed solvent system of DMA and n-octanol. 1 crystallizes in

Ibam, which is an orthorhombic space group, with a sql-

Reaction conditions: Styrene oxide (0.5 mL, 5 mmol); catalyst (0.03

topology structure. In the asymmetric unit, there are two Mn ,

mmol based on Mn ); TBAB (0.1 mmol); CO : 1 atm. Without

2−

TBAB. The products were analyzed and identiﬁed by gas

one L , and one water molecules. The Mn ion is ﬁve-

chromatography.

coordinated by one H O molecule and four carboxylic O

2−

atoms separately from ligands (κ -κ )-(κ -κ )-μ -L (Figure

b). 1 showed an uncommon Mn paddle-wheel building unit

with the two ends of the Mn centers coordinated by two H O

simulated data, conﬁrming the crystalline structure of the

obtained samples (Figure S4, Supporting Information ). As

shown in the XPS patterns (Figure S7, Supporting

Information), the Mn 2p₃_/₂peak of 1 is around 641.4 eV

with a satellite feature of ca. 646 eV, indicating the +2 valence

of the manganese element. The TGA measurement was carried

molecules to form the penta-coordinated mode (Figure 1a).

Each SBU is coordinated with four curved ligands to build a

D layer with rhombic lattices (Figure 1b). Because of the

curved ligands, every two 2D layers interlace with each other to

form a 2-fold interpenetrating conformation (Figure 1c). The

distances of Mn−O range from 2.040(12) Å to 2.446(16) Å,

and the angles of O−Mn−O are in the scope of 55.0(5)−

in N atmosphere from 25 to 800 °C (Figure S10, Supporting

Information). From 25 to 350 °C, a weight loss of 24.0% was

78.1(7)°. The PXRD pattern shows that the peak positions of

observed, corresponding to the loss of solvent molecules in the

the obtained crystalline samples of 1 match well with the

lattice and the coordinated H O molecules. When increasing

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2−

κ )-(κ -κ -μ )-μ -L . Another Mn ion coordinates with three

2−

O atoms from three carboxylic O from one (κ -κ )-(κ )-μ -L

and two (κ -κ )-(κ -κ -μ )-μ -L , and three other O atoms

2−

from H O molecules (Figure 2). Each SBU is coordinated by

four ligands to build a 2D layer with quadrate lattices (Figure

b), and every two 2D layers interlace each other to form a 2-

fold interpenetrating conformation as well (Figure 1c). The

distances of Mn−O range from 1.943(6) Å to 2.635(9) Å, and

the angles of O−Mn−O are in the scope of 59.1(2)−

177.0(2)°. As shown in Figure S5, Supporting Information, the

PXRD pattern of obtained 2 is in good agreement with the

simulated data, conﬁrming the crystalline structure of the

obtained samples. The Mn 2p ₃ _/₂ peak of 2 in XPS patterns

(

Figure S8, Supporting Information ) is around 641.4 eV with a

satellite feature of ca. 646 eV indicating the +2 valence of the

manganese element. As shown in the TGA measurement

(

Figure S11, Supporting Information ), a weight loss of 18.6%

was observed from 25 to 375 °C, corresponding to the loss of

Figure 3. Recycling experiments for catalysts 1, 2, and 3.

solvent molecules in the lattice and the coordinated H O

molecules. The structure of 2 began to decompose after further

heating after 400 °C, also demonstrating the thermal stability

Scheme 2. Substrate-Scope Survey of 2 and 3 for CO₂

Coupling with Epoxides Toward the Production of Cyclic

Carbonates

of 2. Probably due to the more ionic nature of the Mn cation

in MnCl than that in Mn(OAc) , the formed dinuclear Mn

nodes in 2 suﬀered less steric hindrance and more potential

active sites than the Mn ions in the paddle-wheel unit of 1,

which might be advantageous to improve the catalytic activity.

Crystal Structure of [Mn (L) (DMF) (H O)]·3DMF (3).

Considering that the 2-fold interpenetration structure of 2 may

impact the entrance of components and the release of

products, we successfully synthesized 3 by changing the

mixed solvent system used for the preparation of 1 and 2 with

DMF and acetonitrile. As shown in Figure 1a, 3 exhibits the

dinuclear Mn nodes similar to 2, except that two of the three

coordinated H O molecules were replaced by DMF. 3 belongs

to P1, which is a triclinic space group, with a sql-topology

structure. There are two six-coordinated Mn , four ligands,

two DMF molecules, and one H O molecule in the asymmetric

unit. Similar to 2, one of the Mn ions in SBU is linked to six

2−

carboxylate O atoms from two (κ -κ )-(κ )-μ -L and two (κ

2−

κ )-(κ -κ -μ )-μ -L , and another Mn ion is coordinated by

three carboxylic O atoms from one (κ -κ )-(κ )-μ -L and two

κ -κ )-(κ -κ -μ )-μ -L as well as three O atoms from two

2 4

2−

(

2 4

DMF and one H O molecule (Figure 2). Each SBU is

Reaction conditions: epoxides (5 mmol); catalyst (0.03 mmol

coordinated by four ligands to build a 2D layer with rhombic

lattices as well (Figure 1b). But unlike 2, the 2D layers of 3 are

stacked up of dislocations to form a non-interpenetrating

conformation (Figure 1c). The distances of Mn−O range from

calculated according to the amount of Mn ); TBAB (0.1 mmol); 70

C and 1 atm CO . Isolated product obtained by column

chromatography separation.

2.074(3) Å to 2.359(3) Å, and the angles of O−Mn−O are in

to 400 °C, the structure began to decompose, illustrating the

thermal stability of 1.

the scope of 57.75(10)−176.26(14)°. The phase purity of

obtained 3 was also conﬁrmed by PXRD (Figure S6,

Supporting Information ), and the Mn 2p3/2 peak of 3 the

XPS data is also around 641.4 eV with a satellite feature of ca.

646 eV indicating the +2 valence of manganese element

(Figure S9, Supporting Information). The TGA measurement

Crystal Structure of [Mn (L) (H O) ]·2DMA (2). Never-

theless, since each Mn²center in 1 coordinated only one

solvent molecule, the potential active sites of 1 were relatively

limited. It is known that the structure of MOFs is aﬀected by

various synthetic factors including temperature, solvent, metal,

in N atmosphere shows the thermal stability of 3 as well

4−37

and anion.

Accordingly, we synthesized 2 with MnCl

(Figure S12, Supporting Information). From 25 to 310 °C, a

weight loss of 25.7% was observed, corresponding to the loss of

solvent molecules in the lattice and the coordinated DMF and

instead of Mn(OAc) as the Mn resource for the synthesis of

. 2 crystallizes in Pc, which is a monoclinic space group, with a

sql-topology structure. There are two crystallographically

H O molecules. The structure began to decompose after

independent six-coordinated Mn²⁺ions, two ligands, and

further heating after 400 °C.

three H O molecules in the asymmetric unit (Figure 1a). One

Catalytic Cycloaddition of CO with Styrene Oxide

Mn ion of the Mn ions in the SBU is coordinated with six

toward Cyclic Carbonate. The catalytic properties of 1−3

2−

carboxylic O atoms from two (κ -κ )-(κ )-μ -L and two (κ -

for epoxide carboxylation by CO were surveyed with styrene

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Figure 4. Proposed mechanism of the cycloaddition of CO to epoxides with 1 (a) and 2/3 (b) as catalysts.

oxide as the model under atmospheric pressure and solvent-

free conditions.

3 exhibited outstanding catalytic activities under the solvent-

free soft conditions with a limited cocatalyst dose. When a

substrate with a relatively bulky substituent such as naphthoxyl

was used, the product yields were drastically decreased for both

2 and 3 because of the stiﬀ nature and the diﬃculty to enter

the MOF pore of the substrate. Notably, for the coupling of

was chosen at ﬁrst to investigate the optimized conditions

(

entries 1, 4, 7, and 10 in Table 2). As the temperature

increases, the yields of the desired products also increased and

reached the highest 98% yield at 70 °C after 48 h. Under the

same conditions, the activities of 2 and 3 were tested to explore

CO with cyclohexene oxide, the performance of 2 and 3 was

the inﬂuence of structure on the catalytic couplings of CO . At

quite diﬀerent. The yield given by 2 was only 21%, while

catalyst 3 led to a yield as high as 86%, indicating the higher

activity of 3 over 2 originating from the abundant Mn active

sites and the proper pore space of the non-interpenetrated

structure of 3. It is worthy to mention that the cycloaddition of

either 50 or 60 °C, 2 and 3 exhibited signiﬁcantly higher

activities than 1 according to the obtained product yield, which

should be attributed to the less steric hindrance and more

potential active sites of 2 and 3. At 70 °C, almost all of the

styrene oxide was converted into cyclic carbonate by catalysts 2

and 3.

To explore the reusability of these Mn-MOFs catalysts, we

collected the residual catalysts and surveyed the catalytic CO₂

conversion with the regenerated catalysts. As shown in Figure

cyclohexene oxide by CO is relatively diﬃcult in comparison

to other epoxides due to the steric hindrance of the tertiary

7,38

carbons.

To achieve a high conversion rate of cyclohexene

39,40

oxide, a very high reaction pressure is usually required,

while 3 shows a rare catalyst for eﬃciently production of

hexahydrobenzo[d][1,3]dioxol-2-one under such mild con-

ditions.

, the activity of 1 showed a ca. 35% decrease after ﬁve cycles,

while the regenerated 2 and 3 still retained the product yields

92%, indicating the successful structural adjustment of the

26,41

On the basis of previous reports and the reaction results,

we proposed the mechanism of the cycloaddition of CO to

Mn-MOFs for achieving the optimized activity. PXRD patterns

of the regenerated catalysts conﬁrmed the better stability of 2

and 3 than that of 1 during the cycloaddition reactions, as

shown in Figures S4−S6, Supporting Information, which is

consistent with the relatively poor recycled catalytic perform-

ance of 1.

epoxides with 1 and 2/3 as catalyst in Figure 4. The oxygen

atom in the epoxide, as a Lewis base, combines with the Lewis

acidic Mn sites to form an intermediate, which is attacked by

−

nucleophilic Br in TBAB on the β-carbon of the substrate

with a ring-opening process. After insertion of CO and

−

elimination of Br , the cyclic carbonate product is ﬁnally

In addition, a cocatalyst, such as TBAB, is almost inevitable

formed and released from the Mn center, and the catalyst and

cocatalyst are regenerated.

for the CO cycloaddition, which is important for the ring

opening of propylene oxide derivates. However, most MOF-

catalytic systems require extremely high amounts of TBAB,

which leads to the increase of costs and pollution risk.

25,26

4. CONCLUSION

Beneﬁting from the high activity and the assistance eﬀect of the

newly synthesized Mn-MOFs, a TBAB/substrate molar ratio of

only 1:50 was suﬃcient in the reactions. As far as we know, this

is an extremely low TBAB dose among the reported MOF

We synthesized three new Mn-MOFs with the ligand H₂L

sequentially. The SBUs of Mn-MOFs are tuning from paddle-

wheel SBUs to the dinuclear Mn nodes with more potential

active sites via the adjustment of the anions of the manganese

salt. Furthermore, we successfully controlled the conformation

of Mn-MOFs from 2-fold interpenetrating into non-inter-

penetrating by adjusting mixed solvent systems. Along with the

strategy of structural modiﬁcation, both activity and reusability

of the Mn-MOFs are successfully improved in the solvent-free

catalysts for the CO cycloaddition reactions, as compared in

Table S4, Supporting Information .

To show the generality of the Mn-MOF catalysts, we

surveyed the substrate-scope tests of 2 and 3 as shown in

Scheme 2. For the epoxides with diﬀerent substituents

including chloro, phenoxyl, and methylphenoxyl, both 2 and

cycloaddition of CO . Under the mild condition of

733

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1) Tortajada, A.; Juliá-Hernández, F.; Börjesson, M.; Moragas, T.;

Article

atmospheric pressure and 70 °C, the Mn-MOFs catalyze CO₂

to react with epoxides for the production of cyclic carbonate

without solvent and signiﬁcantly economize the consumption

of cocatalyst TBAB. The eﬃcient catalytic conversion of CO₂

with various epoxides including cyclohexene oxide was

achieved. Our work should contribute to the design and

structural modiﬁcation of Mn-MOFs catalysts as well as

corresponding activity improvement and may provide new

ACKNOWLEDGMENTS

■

This work was supported by the National Key R&D Program

of China (2016YFB0600902) and the NSFC (21771112 and

21875120).

REFERENCES

■

(

Martin, R. Transition-metal-catalyzed carboxylation reactions with

materials for CO management and conversion.

carbon dioxide. Angew. Chem., Int. Ed. 2018 , 57 , 15948 −15982.

2) Saptal, V. B.; Bhanage, B. M. Current advances in heterogeneous

catalysts for the synthesis of cyclic carbonates from carbon dioxide.

Curr. Opin. Green Sust. 2017, 3, 1−10.

ASSOCIATED CONTENT

■

sı Supporting Information

The Supporting Information is available free of charge at

https://pubs.acs.org/doi/10.1021/acs.cgd.1c00037.

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AUTHOR INFORMATION

■

Corresponding Authors

(9) He, H.-M.; Sun, Q.; Gao, W.-Y.; Perman, J. A.; Sun, F.-X.; Zhu,

Xiao Liu − Department of Chemistry and Key Laboratory of

Advanced Energy Material Chemistry, College of Chemistry,

Nankai University, Tianjin 300071, P. R. China;

orcid.org/0000-0001-8077-3000; Email: lx@

nankai.edu.cn

Peng Cheng − Department of Chemistry and Key Laboratory

of Advanced Energy Material Chemistry, College of

Chemistry, Nankai University, Tianjin 300071, P. R. China;

orcid.org/0000-0003-0396-1846; Email: pcheng@

nankai.edu.cn

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Authors

Haonan Lin − Department of Chemistry and Key Laboratory

of Advanced Energy Material Chemistry, College of

Chemistry, Nankai University, Tianjin 300071, P. R. China

Cheng-Hua Deng − Department of Chemistry and Key

Laboratory of Advanced Energy Material Chemistry, College

of Chemistry, Nankai University, Tianjin 300071, P. R.

China

Xiaohang Qiu − Department of Chemistry and Key

Laboratory of Advanced Energy Material Chemistry, College

of Chemistry, Nankai University, Tianjin 300071, P. R.

China

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Jian-Gong Ma − Department of Chemistry and Key

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of Chemistry, Nankai University, Tianjin 300071, P. R.

China; orcid.org/0000-0001-7407-5521

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