Cyanosilylation of aldehydes catalyzed by a porous metal-organic framework containing a coordinatively unsaturated Zn(II) center and its anticancer activity in human osteogenic sarcoma

Article abstract of DOI:10.1080/00958972.2019.1659963

Solvothermal reaction of Zn(NO₃) · 6H₂O with the tripodal ligand 1,3,5-tris(4-carboxyphenyl)benzene (H₃BTB) afforded a highly porous metal-organic framework (MOF) {[Zn₃(BTB)₂(H₂O)₂

Full text of DOI:10.1080/00958972.2019.1659963

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: https://www.tandfonline.com/loi/gcoo20
Cyanosilylation of aldehydes catalyzed by a
porous metal-organic framework containing a
coordinatively unsaturated Zn(II) center and its
anticancer activity in human osteogenic sarcoma
Yu-Xu Li, Gang Chen, Qiang Xiao, Jin-Hui Cheng, Zhi-Sheng Long, Liang Deng,
Ling Ma & Fei-Peng Gong
To cite this article: Yu-Xu Li, Gang Chen, Qiang Xiao, Jin-Hui Cheng, Zhi-Sheng Long,
Liang Deng, Ling Ma & Fei-Peng Gong (2019): Cyanosilylation of aldehydes catalyzed by a
porous metal-organic framework containing a coordinatively unsaturated Zn(II) center and its
anticancer activity in human osteogenic sarcoma, Journal of Coordination Chemistry, DOI:
10.1080/00958972.2019.1659963
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JOURNAL OF COORDINATION CHEMISTRY
https://doi.org/10.1080/00958972.2019.1659963
Cyanosilylation of aldehydes catalyzed by a porous
metal-organic framework containing a coordinatively
unsaturated Zn(II) center and its anticancer activity in
human osteogenic sarcoma
Yu-Xu Lia†, Gang Chena†, Qiang Xiaoa, Jin-Hui Chenga, Zhi-Sheng Longa, Liang
Denga, Ling Mab and Fei-Peng Gonga
b
aDepartment of Orthopedics, Jiangxi Provincial People’s Hospital, Nanchang, China; Department of
Cardiology, The 940th Hospital Joint Logistics Support Force of Chinese People’s Liboration Army,
Lanzhou, China
ABSTRACT
ARTICLE HISTORY
Received 13 May 2019
Accepted 10 August 2019
Solvothermal reaction of Zn(NO3) ꢀ 6H2O with the tripodal ligand
1,3,5-tris(4-carboxyphenyl)benzene (H3BTB) afforded a highly por-
ous metal-organic framework (MOF) {[Zn3(BTB)2(H2O)2] ꢀ 7DMF}n
(1). The resulting activated 1a exhibits BET surface areas of
1021 m2 gꢁ1 with a pore size distribution around 11.8Å, which
was further applied in the cyanosilylation of aldehydes under
solvent-free conditions. The experimental results show that, using
1a as the catalyst, both aliphatic and aromatic aldehydes were
efficiently transformed to cyanohydrin trimethylsilyl ether.
Meanwhile, significant size selectivity and electronic effects have
also been observed. Then, we evaluated the anticancer activity of
the synthesized compound 1a on six different kinds of cancer cell
lines, including HeLa, CHO, HepG2, MG-63, MAD-MB-435, and
BEAS-2B. CCK-8 results indicated 1a showed excellent inhibitory
effect on cell proliferation, especially on the MG-63 human osteo-
genic sarcoma cells. Next, a transwell assay was performed to
detect the migration and invasion activity of MG-63 cells after
compound 1a treatment.
KEYWORDS
Porous MOF; unsaturated
Zn(II) centers;
cyanosilylation reaction; size
selectivities; anticancer
activity; transwell assay
CONTACT Fei-Peng Gong
feipeng_gong1980@126.com
Department of Orthopedics, Jiangxi Provincial
People’s Hospital, Nanchang 330006, China.
†These authors contributed equally to this work.
Supplemental data for this article is available online at https://doi.org/10.1080/00958972.2019.1659963.
ß 2019 Informa UK Limited, trading as Taylor & Francis Group

2
Y.-X. LI ET AL.
Abbreviations: HeLa: human cervical cancer cell line; CHO:
Chinese hamster ovary cell line; HepG2: liver cancer cell line; MG-
63: human osteogenic sarcoma cell line; MDA-MB-435S: breast
cancer cell line; BEAS-2B: normal human lung epithelial cell line
1. Introduction
Cyanohydrins play an important role in chemistry and biology [1]. They are widely
employed as versatile building blocks for fine chemicals, agrochemicals, and pharma-
ceuticals, i.e. a-hydroxy acids, b-amino alcohols, etc. Generally, the addition of cyanide
to carbonyl compounds represents one of the fundamental approaches for their prep-
aration and has frequently been at the forefront of synthetic chemistry [2]. In consider-
ation of easy and safe management, the most often used cyanide source is
trimethylsilyl cyanide (TMSCN), which allows the cyanohydrins to be prepared as the
corresponding trimethylsilyl ether [3–5]. Over the past several decades, a variety of
activators or promoters have been reported for this transformation. In light of pressure
to develop environmentally benign systems, organocatalysts have grown rapidly in
promoting the cyanosilylation of carbonyl compounds with TMSCN. Although organo-
catalytic systems comply with some features of green chemistry, they are still encoun-
tered with tedious separation and recycling problems in practical applications [6].
Therefore, a mild, efficient and environmentally friendly synthetic method for cyano-
hydrin trimethylsilyl ethers is still highly desirable.
As an emerging class of porous crystalline material, metal-organic frameworks can
be synthesized from metal ions and organic multi-dentate ligands under mild condi-
tions [7–9]. These materials have certain desirable properties such as large surface
area, different pore volumes, and their distribution, size, and shape of pores, etc., that
can be controlled via ligand design as well as choice of metal ion(s). Furthermore,
compared with other heterogeneous catalysts, the ordered nature of MOFs allows for

JOURNAL OF COORDINATION CHEMISTRY
3
precise characterization of catalytic sites through X-ray diffraction studies, which
makes their catalysis center and the pore surroundings resolvable [10]. The vacant
coordination sites in MOFs can activate carbonyl compounds for nucleophilic addition
in a manner similar to Lewis acids. Since the first example of a MOF catalyzed reaction
was reported by Fujita et al., dozens of papers concerning MOF-based heterogeneous
catalysis have been thus far published [11–13]. More specifically, Kaskel and co-work-
ers demonstrated that pure MIL-101(Cr) is an efficient catalyst for the cyanosilylation
of benzaldehyde [14]. Long et al. used a Mn(II)-based MOF as a catalyst for cyanosilyla-
tion reactions [15]. It is proposed that the Mn(II) ions exposed on the surface of the
framework act as Lewis acid sites. Despite the progress on MOFs catalyzed reactions,
there has been little focus on the investigation of cyanosilylation reactions using por-
ous Zn(II)-based MOFs with unsaturated Zn(II) centers as the heterogeneous catalyst
since ZnCl2 has already been proved as an effective homogeneous catalyst for cyanosi-
lylation reactions [16]. On the other hand, the construction of metal-based anticancer
drugs has received great attention in the past few decades since the clinical success
of cisplatin [17]. To overcome the toxicities of platin-based anticancer drugs, many
low cost first-row transition metal ions have been studied as coordination centers of
potential anticancer agents [18]. Zinc is an important biometal, essential for life, which
is second only to iron in terms of its concentration in biological systems and is present
in more than 300 enzymes of living organisms. Recent studies provided compelling
evidence that Zn(II) derivatives have proved to be potential anticancer agents with
low in vivo toxicity, low side effects and perhaps new modes of action and cellular tar-
gets compared with the classical metallodrugs [19–21]. In this study, a new porous
metal-organic framework {[Zn3(BTB)2(H2O)2]ꢀ7DMF}n (1), along with its activated sample
1a was prepared, and their catalytic cyanosilylation performances and anticancer activ-
ity were studied.
2. Experimental
2.1. Materials and instrumentation
The H3BTB ligand was obtained from the Jinan Henghua Sci. & Tec. Co. Ltd. and used
without purification. Zn(NO3)2 ꢀ 6H2O, TMSCN, and aldehydes were purchased from
Beijing Bailingwei Chemical Reagent Company (Beijing, China) in analytical grade. The
solvents used in this work were purchased from Tianjin Fuchen Chemical Reagents
Company Limited (Tianjin, China). Elemental analyses (C, H, and N) were determined
with a Perkin-Elmer 240 elemental analyzer. Thermogravimetric analysis waꢁs1carried
out on a NETSCHZ STA-449C thermo-analyzer with a heating rate of 10ꢂ min under
a nitrogen atmosphere. Powder X-ray diffraction (PXRD) analyses were recorded on a
Bruker AXS D8 advanced automated diffractometer with Cu-Ka radiation.
2.2. Cell and culture condition
Human cervical cancer cell line HeLa, Chinese hamster ovary cell CHO, the liver cancer
cell line HepG2, human osteogenic sarcoma cell line MG-63, breast cancer cell line
MDA-MB-435S, and the normal human lung epithelial cell line BEAS-2B were

4
Y.-X. LI ET AL.
purchased from Biological Sciences (Shanghai, China), CAS. The HeLa, HepG2, MG-63,
MDA-MB-435S, and BEAS-2B cells were cultured in Dulbecco’s Modified Eagle’s
Medium (DMEM) medium, and CHO cells were cultured in 1640 culture medium
(Gibco, Carlsbad, CA, USA). Both the DMEM and 1640 culture media were supple-
mented with 10% heated-fetal bovine serum, 100 U mLꢁ1 penicillin-streptomycin solu-
tion (HyClone, UT, USA). The above cells were cultured in an incubator at 37 ꢂC,
5% CO2.
2.3. Synthesis of catena-[bis(l-1,3,5-tris(4-carboxylatophenyl)benzene)-
(l-hydrate)-trizinchepta-N,N-dimethylformamide solvate] (1)
A mixture of 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB) (15.4 mg, 0.035 mmol) was
added to 3 mL of 1:1 (v/v) H2O/dimethylformamide (DMF) solution, then Zn(NO3)2 ꢀ 6H2O
(40.2 mg, 0.135 mmol) and three drops of concentrated nitric acid were added. The solu-
tions were mixed well in a 20 mL glass scintillation vial, and then heated to 90ꢂ and kept
at that temperature for 3 days. After cooling slowly to room temperature, colorless block
crystals were isolated with 36% yield (10 mg) based on H3BTB. Anal. Calcd (%) for 1
C75H83N7O21Zn3: C, 55.79; H, 5.18; N, 6.07%. Found: C, 55.91; H, 5.42; N, 6.24%. Prominent
FT-IR peaks for 1 (KBr pellet, cmꢁ1): 3468(m), 2965(m), 2874(m), 2322(w), 2302(w),
1612(s), 1472(m), 1369(m), 1121(s), 1019(m), 934(s), 817(s), 779(s), 708(m).
2.4. X-ray crystallography
Single-crystal X-ray crystal data of 1 were collected on a computer-controlled Oxford
Xcalibu E diffractometer with enhanced (Mo) X-ray Source (k ¼ 0.71073 Å) at room
temperature. The data collection was performed using the CrysAlisPro software (ver-
sion: 1.171.36.32) and then reduced to HKL file format using the same software [22].
Empirical absorption correction was performed using spherical harmonics, imple-
mented in SCALE3 ABSPACK scaling algorithm [23]. The structure was solved by
SHELXT [24] and then refined using the SHELXL [25] embedded in the OLEX2 software
package [26]. All non-hydrogen ions were refined anisotropically and all H ions were
generated in their ideal locations. Crystallographic data and refinement details are
summarized in supplementary Table S1, and selected bond distances and angles for 1
are given in supplementary Tables S2 and S3 in the ESI.
2.5. Catalytic test for cyanosylation reaction
A suspension of an aldehyde (1.0 mmol), trimethylsilyl cyanide (TMSCN, 2.0 mmol) and
catalyst (0.5 mol %, 1 or 1a) was placed in a Schlenk tube under a nitrogen atmos-
phere and then the mixture was stirred at room temperature under solvent-free condi-
tions. After that, the catalyst was removed by centrifugation and then washed quickly
with ethyl acetate. The conversion of aldehydes was determined by gas chromatog-
raphy (GC, Agilent 7890A) analysis.

JOURNAL OF COORDINATION CHEMISTRY
5
2.6. Cell viability measurement
For the cell viability detection, the cell counting kit-8 (CCK-8) assay (Sigma-Aldrich,
USA) was performed according to the manuscript’s protocols with a little modification.
In brief, the cancer cells and BEAS-2B normal cells in the logarithmic growth phase
cancer cells were seeded into 96-well plates with the final concentration of 1 ꢃ 104
cells per mL, and the cells were incubated in an incubator at 37ꢂ, 5% CO2 for 12 h.
When the cells reached the confluence of 70–80%, the serial dilutions of 1a (0, 2.5, 5,
10, 25, 50, 100, and 200 lg mLꢁ1) were exposed to cells for 24 h treatment at 37ꢂ, 5%
CO2. Cisplatin was used as the positive control drug added into wells for the same
treatment. After treatment, the culture medium was discarded and fresh medium sup-
plemented with 100 lL CCK-8 medium was added into the wells for another 4 h of cul-
tivation. Finally, the optical density (OD) at 450 nm of each group was measured by
enzyme immunoassay analyzer (Bio-Rad, USA). Each group had three repeats.
2.7. Transwell assays
The migration and invasion ability of cancer cells and BEAS-2B normal cells after being
treated with compound 1a, free ligand (H3BTB ligand) and metal ion (Zn(NO3)2 ꢀ 6H2O)
was determined. The free ligand and metal ion were used at the concentration of
0.5 mol%, and 1:1 (v/v) H2O/dimethylformamide (DMF) was used as the solvent. Results
were detected by transwell assay as described previously with some modifications. In
short, for cell the migration assays, 24-well transwell chambers (Corning, NY, USA) were
placed into cell culture plates before experiments. Then, the MG-63 human osteogenic
sarcoma cells were planted onto the upper chamber in DMEM culture medium without
FBS, and DMEM culture medium with 10% FBS was added into the lower chamber. After
24 h of culture at 37ꢂ, 5% CO2, the cells remaining on the upper membrane were
wrapped carefully, and the cells on the lower surface of the membrane were stained
with 0.5% crystal violet. The numbers of cells on the lower surface of the membrane
were quantified with a microscope. For the cell invasion assay, the 24-well transwell
chambers used in this experiment were pre-coated with matrigel matrix (BD Biosciences,
NJ, USA) and then the measurement was conducted according to the above protocols.
3. Results and discussion
3.1. Crystal structure of 1
The single-crystal X-ray diffraction study reveals that 1 belongs to the orthorhombic
space group Pnma and shows a 3-D framework structure composed of the triangular
prism-shape {Zn3(CO2)6(H2O)2} as the secondary building unit (SBU). The asymmetric
unit of 1 is composed of one and a half Zn(II) ions, one-half l3-bridging water mol-
ecule, one-half l1-coordinating water molecule, one fully deprotonated BTB3ꢁ ligand
and three disordered lattice DMF molecules as revealed via the TGA analyses, all of
which contribute to a neutral framework structure. The two Zn(II) ions in the molecular
unit show different coordination environments. The Zn1 ion located on the inversion
center is six-coordinate by four carboxylate O ions, one l3-bridging water molecule

6
Y.-X. LI ET AL.
and one l1-coordinating water, forming a distorted octahedral geometry. The tetrahe-
dral coordination geometry of Zn2 ions is finished by four carboxylate O ions from
four different BTB3ꢁ ligands. The Zn1-O bond distances are in the range of 2.053(2) to
2.109(3) Å and the Zn2–O bond distances are in the region of 1.913(4) to 2.011(2) Å,
which are all comparable with those observed in other Zn(II)-based MOFs based on
the same H3BTB ligand [27, 28]. It could be found that the distances for the Zn1–O
bonds are larger than those for the Zn2–O bonds, which might be due to their differ-
ent coordination geometries. Two Zn2 ions and one Zn1 ion are coupled together via
the l3-bridging water molecule along with four bidentate chelating and two mono-
dentate coordination carboxylic groups to afford the {Zn3(CO2)6(H2O)2} SBU whose axis
position is occupied via the coordinated water molecule (Figure 1). As for the BTB3ꢁ
ligand, it acts as a five-connected node in which the carboxylic groups are in the l5-
g0:g1:g1:g1:g1:g1 coordination mode. Such a coordination pattern of BTB3ꢁ ligand has
been reported in other MOFs [29]. The connection of the {Zn3(CO2)6(H2O)2} SBU with
the BTB3ꢁ ligand leads to the formation of a highly porous 3-D framework with 2-D
pores along the a and b axes. The void space for the single network is large enough
for the accommodation of another identical network to form a twofold interpene-
trated framework (Figure 1(c)). Although twofold interpenetrated, the framework of 1
still holds considerable solvent accessible voids of 63.3% as calculated via the software
PLATON. Together with the large solvent accessible void, there also exist 2-D rhombic
Figure 1. (a) View of the asymmetric unit of 1 and the coordination environments of Zn(II) ions.
(b) The coordination mode of the organic ligand. (c) The 3-D framework of 1. (d) A view of twofold
interpenetration.

JOURNAL OF COORDINATION CHEMISTRY
7
channels running along the a and b axes with a window size of 11.95ꢃ9.28 Å2 whose
vertices are filled with the water coordinated Zn(II) centers (Figure 1(d)).
3.2. PXRD, TGA, and BET analyses
To check the phase purity of the bulk as-prepared complex 1, crystalline samples in
different reaction systems were collected and the corresponding PXRD pattern was
collected at room temperature. PXRD of the as-synthesized 1 gives fully matched dif-
fraction patterns compared to the simulated patterns from single-crystal data, reflect-
ing good phase purity, and well-defined structure (Figure 2). Thermal stability of 1 was
determined by thermogravimetric analysis (TGA). As shown in Figure 2(b), the dehy-
dration processes of 1 started from 120ꢂ. With further heating, it showed fast and con-
tinuous weight loss of 33.2% until 250ꢂ, which can be assigned as the removal of one
coordinated H2O and seven lattice DMF molecules per unit (calcd 32.8%). Then, it
showed a slow weight loss and decomposed after 420ꢂ (Figure 2(b)). The third decom-
position step was detected in the temperature range of 550–610ꢂ; this could be attrib-
uted to decomposition of the organic ligand giving off CO2 and H2O gases leaving
ZnO as the final product (JCPDS: 36-1451) [30]. To evaluate the permanent porosity,
the as-synthesized samples of 1 were immersed in acetone for 3 days to remove the
high-boiling DMF solvents, which were further outgassed overnight under vacuum at
Figure 2. (a) The PXRD patterns for 1 and 1a. (b) The TGA curve for 1. (c) The 77 K N2 sorption
isotherm for 1. (d) The measured pore size distribution (PSD) curve based on the density-functional
theory (DFT) method.

8
Y.-X. LI ET AL.
100ꢂ for 1 day to afford the activated 1a. The PXRD pattern of 1a collected at room
temperature reflected its good match with the one of as-prepared samples, indicating
1 kept its framework integrity in the solvent exchange and the activation processes
[31]. N2 sorption isotherms at 77 K of 1a display the typical type-I sorption behavior
with a maximum uptake capacity of 268 cm3 g–1, illustrating a typical crystalline micro-
porous nature for 1a. Based on the N2 sorption isotherm, the calculated Langmuir and
BET surface areas of 1a are 1148 and 1021 m2 gꢁ1. The measured pore size distribu-
tion (PSD) curve based on the density-functional theory (DFT) method shows the main
pore sizes of 8.03 and 11.8 Å, which is related to the window size for the channels run-
ning along the a and b axes (Figure 2(d)).
3.3. Catalytic activity
The cyanosilylation reaction between TMSCN and benzaldehyde was chosen as the
model reaction system to assess the catalytic properties of 1a with the untreated com-
plex 1 as the reference. As shown in Table 1, the reaction without catalyst resulted in
only 13% conversion of benzaldehyde. However, in the presence of 0.5 mol% of catalyst,
we were pleased to find that the addition of the MOF can accelerate this reaction under
solvent-free conditions and 1a gives a higher conversion at the same time intervals than
that of 1. Since 1 and 1a are constructed by the same building blocks but with different
metal sites, the different reaction rate is mainly related with the nature of functional sites
in the catalysts. Coordinatively unsaturated metal ions can act as Lewis acid sites and
coordinate with the carbonyls, which could activate the carbonyls and facilitate the
nucleophilic attack by the TMSCN. Complex 1 shows a much higher catalytic activity
than that of the blank experiment, which might be due to the release of DMF and coordi-
nated water molecules from the cavities, and a similar observation has also been
reported in the literature [32]. When using the Zn(NO3) ꢀ 6H2O as the catalyst, only 39%
yield was observed, which indicates that the open Zn(II) center is more cationic and a
stronger Lewis acid than mononuclear Zn(NO3) ꢀ 6H2O. To study the effect of substituent
Table 1. The results for the catalytic cyanosilylation of aldehydes in the presence of differ-
ent catalysts.
Entry
Catalyst
Time (h)
Conv.a (%)
1
2
3
4
none
1
1a
Zn(NO3)2 ꢀ 6H2O
3 h
3 h
3 h
3 h
13
43
98
39
aConversion determined by GC.

JOURNAL OF COORDINATION CHEMISTRY
9
Table 2. The results for the catalytic cyanosilylation of aldehydes in the presence of differ-
ent catalysts.
Entry
R
Time (h)
Yielda (%)
1
2
3
4
5
6
7
(CH3)2CH
n-C7H15
C6H5
2-NO2C6H4
3-OCH3C6H4
2-Furanyl
1-Naphthyl
3 h
3 h
3 h
3 h
3 h
3 h
3 h
100
100
98
100
89
92
21
aConversion determined by GC.
groups on the cyanosilylation reaction, various aldehydes were used as the reaction sub-
strates. As indicated in Table 2, both aliphatic and aromatic aldehydes are well tolerated
with this reaction protocol and could be converted to the corresponding O-trimethylsilyl
cyanohydrin in good yields. Aliphatic aldehydes and benzaldehydes bearing electron-
withdrawing groups on aromatic rings proceed smoothly to give the respective cyanosi-
lylation products with high yields. Benzaldehydes bearing electron-donating groups
react much more slowly than benzaldehydes with electron-withdrawing groups. To fur-
ther probe the size selectivity of 1a, larger size aromatic 1-naphthaldehydes were used
as substrates. It is with no surprise that significant size selectivity is observed with 1a
and yields for both substrates decrease dramatically as compared with benzaldehyde in
the following order: benzaldehyde > 1-naphthaldehyde. The relative substrate dimen-
sions indicated that the pore windows of 1a are large enough to allow benzaldehyde
(8.21 ꢃ 5.83 Å2) to diffuse swiftly through the channels to reach the catalytic active cen-
ters. In contrast, a significant decrease in reaction rate was observed for larger size sub-
strates. The yield for 1-naphthaldehyde (12.69 ꢃ 8.29 Å) reduced to 21% under similar
conditions. As evident for the above results, 1a demonstrated its size selectivity and
applicable substrate dimensions.
Based on the experimental results and previously reported results, a plausible reac-
tion mechanism is proposed to illustrate the process of 1a0 catalyzed cyanosilylation
reaction [11–14]. The labile water molecules in the channels of 1 were removed by
heating to expose the unsaturated metal sites previously. The aldehydes were acti-
vated by the coordinatively unsaturated Zn centers to react with TMSCN (Scheme 1).
The products were replaced by aldehydes, and the catalysts continued to activate the
aldehydes in the next catalytic cycle.
3.4. Compound 1a showed special inhibitory effect on MG-63 human
osteogenic sarcoma cells
After the design and synthesis of 1a with its novel structure, the anticancer activity of
1a was further explored. In this research, the CKK-8 assay was conducted to detect

10
Y.-X. LI ET AL.
Scheme 1. Proposed mechanism for the cyanosilylation reaction of carbonyl compounds catalyzed
by 1a.
the cell viability of different types of cancer cells after serial dilution treatment with
1a. As the results show in Figure 3, 1a exhibited no inhibitory effect on MDA-MB-435S
cancer cells, moderate inhibition on HeLa, CHO, HepG2 cancer cells, and excellent
inhibition on MG-63 cancer cells. The IC50 of 1a on MG-63 cancer cells is
2.5 0.3 lg mLꢁ1 (Table 3), which is significantly lower than the IC50 of other cancer
cells, indicating 1a showed a much better inhibition on MG-63 cancer cells compared
with other cells. Based on this data, the MG-63 cell line was selected for research
about the anticancer activity of 1a.
3.5. MG-63 cell proliferation, migration, and invasion after compound
1a treatment
In the previous study, we confirmed that 1a showed special inhibition on the MG-63
human osteogenic sarcoma cells, compared with other cells. Next, we further explored
the inhibitory effect of 1a on cancer cell proliferation, migration, and invasion ability.
The MG-63 cell proliferation was assessed by CCK-8. After treated with 1a at 2.5 mg
mLꢁ1 for 48 h, the cell proliferation curves were plotted. As the results show in Figure
4(a), we can see the compound 1a treatment significantly reduced the proliferation of
cancer cells, in comparison with other control groups, free ligand, and metal ion treat-
ment groups (p < .005). Besides, transwell assay was performed to explore the effect

JOURNAL OF COORDINATION CHEMISTRY
11
Figure 3. The inhibition of 1a on different kinds of cancer cell viability. Different types of cancer
cell lines were exposed to serial concentrations of 1a. A CCK-8 detection kit was used to measure
the cell viability, and the IC50 was calculated according to the results. All experiments were per-
formed at least three times.
Table 3. IC50 Values of compound on cancer cells.
IC50 (lg mLꢁ1
)
HeLa
CHO
HepG2
MG-63
MAD-MB-435
BEAS-2B
1a
24.5 1.6
>250
>250
>250
>250
>250
>250
120 3.4
>250
>250
2.5 0.3
>250
>250
>250
>250
>250
>250
>250
>250
>250
>250
Cisplatin
Free ligand
Metal ion
>250
>250
>250
of 1a on cancer cells migration and invasion ability. From the results exhibited in
Figure 4(b) and (c), we found that the number of migrated and invaded MG-63 cancer
cells could be significantly reduced by 1a, and the free ligand and metal ion had no
effect on the cell migration and invasion ability. Above all, we can draw this conclu-
sion, 1a significantly inhibited MG-63 cells proliferation, migration, and invasion ability.
4. Conclusion
We have prepared a new Zn(II)-based porous metal-organic framework containing
abounding coordinatively unsaturated Zn(II) centers. The structural characterization

12
Y.-X. LI ET AL.
Figure 4. Reduced MG-63 cancer cells proliferation, migration, and invasion after compound 1a
treatment. MG-63 cells were exposed to serially dilutions of 1a. (a) Cell proliferation determined by
cell counting kit-8 assay. (b, c) The cell migration and invasion capability examined by transwell
assay. There is a significant difference with p < .05. All experiments were performed in triplicate.
based on single-crystal data collected at 298 K reveals that 1 shows a 3-D framework
structure with 1-D nano-sized channels along the a axis, which are functionalized with
high density of unsaturated Zn(II) centers. Due to its high BET surface areas and large
pore aperture, the activated MOF was studied as a catalyst for the cyanosilylation of
aldehydes under solvent-free conditions. The experimental results show that using 1a
as the catalyst, both aliphatic and aromatic aldehydes were efficiently transformed to
cyanohydrin trimethylsilyl ether. Meanwhile significant size selectivity and electronic
effects have also been observed. To evaluate the inhibitory effect of 1a on cancer
cells, HeLa, CHO, HepG2, MG-63, MDA-MB-435S, and BEAS-2B cell lines were used for
the CCK-8 assay. Results indicated the excellent anticancer activity of 1a on MG-63
human osteogenic sarcoma cell line, with the IC50 of 2.5 0.3 lg mLꢁ1. Subsequently,
the influence of 1a on MG-63 cells proliferation, migration and invasion capability was
examined using transwell assay. Through the above experiments, we draw the conclu-
sion that 1a inhibited the MG-63 proliferation, migration, and invasion, indicating the
potential of being a candidate for human osteogenic sarcoma treatment.

JOURNAL OF COORDINATION CHEMISTRY
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Disclosure statement
No potential conflict of interest was reported by the authors.
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