Photodegradation of Brilliant Green Dye by a Zinc bioMOF and Crystallographic Visualization of Resulting CO2

Abstract

We present a novel bio-friendly water-stable Zn-based MOF (1), derived from the natural amino acid L-serine, which was able to efficiently photodegrade water solutions of brilliant green dye in only 120 min. The total degradation was followed by UV-Vis spectroscopy and further confirmed by single-crystal X-ray crystallography, revealing the presence of CO2 within its channels. Reusability studies further demonstrate the structural and performance robustness of 1.

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molecules
Article
Photodegradation of Brilliant Green Dye by a Zinc bioMOF and
Crystallographic Visualization of Resulting CO2
Paula Escamilla 1, Marta Viciano-Chumillas 1, Rosaria Bruno 2, Donatella Armentano 2,* , Emilio Pardo 1, *
and Jesús Ferrando-Soria 1, *


Citation: Escamilla, P.; Viciano-
Chumillas, M.; Bruno, R.; Armentano,
D.; Pardo, E.; Ferrando-Soria, J.
Photodegradation of Brilliant Green
Dye by a Zinc bioMOF and
Crystallographic Visualization of
Resulting CO2.Molecules 2021,26,
4098. https://doi.org/10.3390/
molecules26134098
Academic Editor: Liudmil Antonov
Received: 10 June 2021
Accepted: 2 July 2021
Published: 5 July 2021
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Copyright: © 2021 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
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4.0/).
1Departament de Química Inorgànica, Instituto de Ciencia Molecular (ICMOL), Universitat de València,
Paterna, 46980 València, Spain; paula.escamilla@uv.es (P.E.); marta.viciano@uv.es (M.V.-C.)
2Dipartimento di Chimica e Tecnologie Chimiche, Universitàdella Calabria, 87036 Cosenza, Italy;
rosaria.bruno@unical.it
*Correspondence: Donatella.armentano@unical.it (D.A.); emilio.pardo@uv.es (E.P.);
jesus.ferrando@uv.es (J.F.-S.)
Abstract:
We present a novel bio-friendly water-stable Zn-based MOF (
1
), derived from the natural
amino acid L-serine, which was able to efficiently photodegrade water solutions of brilliant green dye
in only 120 min. The total degradation was followed by UV-Vis spectroscopy and further confirmed
by single-crystal X-ray crystallography, revealing the presence of CO
2
within its channels. Reusability
studies further demonstrate the structural and performance robustness of 1.
Keywords:
metal-organic frameworks; amino acids-derived ligands; water remediation; photocat-
alytic degradation; single-crystal X-ray crystallography
1. Introduction
One of the main challenges that modern society faces is related, undoubtedly, to
the contamination of aquatic environments, which is mainly caused by human/industrial
activities [
1
,
2
]. Among the wide diversity of inorganic/organic chemical pollutants, organic
dyes—waste generated in the cosmetic, textile, tannery, or food industries, among others—
constitute one of the major contaminants in industrial wastewater [3].
Proposed solutions for the removal of such organic contaminants include precipita-
tion, coagulation/flocculation, membrane technology, or biological processes [
4
]. However,
probably the two most promising technologies for this purpose are based on the straight-
forward capture of the organic dyes by a porous material or their in-situ photocatalytic
degradation [
5
,
6
]. In particular, metal-organic frameworks (MOFs) are porous crystalline
materials that have already been shown to be efficient in the last two approaches [7–13].
MOFs [
14
,
15
] attract broad attention from many research groups given the great variety
of applications they can exhibit [
14
–
21
]. The reasons for such a variety of applications
are related to a number of unique characteristics such as permanent porosity [
22
,
23
], a
thrilling host-guest chemistry [
24
,
25
]—which can be tuned for fine control over the size,
shape, and functionality of MOF channels—and the possibility of using single-crystal X-ray
diffraction [26–31] (SCXRD) to visualize what is going on within their channels [32].
In particular, MOFs have recently been used in water remediation with exceptional
results. For example, the easy of functionalizing, pre- or post-synthetically, MOF channels
has led to the preparation of specifically designed MOFs for the selective and efficient
capture of both organic and inorganic contaminants [
8
,
33
–
35
]. Moreover, certain specifically
designed MOFs have already been shown to be effective as photocatalysts to degrade
organic pollutants—i.e., organic dyes– into less toxic intermediates or fully degrade them
into CO
2
and H
2
O [
10
,
36
–
40
]. In particular, several Zn(II)-based MOFs have recently been
reported, showing, by analogy with zinc oxide based photocatalysts [
41
,
42
], moderately
good efficiencies as photocatalysts towards different organic dyes [43–45].
Molecules 2021,26, 4098. https://doi.org/10.3390/molecules26134098 https://www.mdpi.com/journal/molecules

Molecules 2021,26, 4098 2 of 9
2. Results
In this communication, we report the preparation and total characterization of a novel
eco-friendly Zn-based MOF, derived from the natural amino acid L-serine, with formula
{Zn
II2
[(S,S)-serimox](H
2
O)
2
]
···
H
2
O (
1
) ((S,S)-serimox = [bis[(S)-serine]oxalyl diamide]
(Figure 1a,b). The final material is capable of photodegrading brilliant green (BG) dye
(Figure 1c) in only 120 min with an efficiency of 100% in the absence of any other oxidant or
co-catalyst. In addition, the high robustness and crystallinity of 1 also allowed us to obtain
the crystal structure of 1—with the help of SCXRD—after the photocatalytic process, which
shows, unambiguously, the presence, within the channels, of CO
2
molecules resulting from
the photodegradation of BG dyes.
Figure 1.
Chemical formulas of the proligand (S,S)-serimox (
a
) and the secondary building units
(SBU) consisting of Zn
II
dinuclear units (
b
). Red oxygen atoms coordinate Zn
II
atoms from another
SBU, whereas green oxygen atoms belong to neighboring SBUs. (
c
) Chemical formula of brilliant
green dye.
The crystal structure of 1 was first determined at 100 K. It crystallizes in the chiral P4
1
2
1
2
space group of the tetragonal system and consists of a chiral 3D pillared square grid where
[Zn
II2
(S,S)-serimox] moieties are located on the vertices of the edges
(Figures 2and 3a)
. The
robust uni-nodal three-connected srs nets are built up from trans oxamidato-bridged Zn(II)
dimeric units, {Zn
II2
[(S,S)-serimox]} (Figure 2and Figure S1), which are connected to each
other through their carboxylate groups (Figure 2, Figures S1 and S2).
Figure 2.
Perspective view of a fragment of 1 emphasizing the central dinuclear Zn
2
SBU (
b
) unit and
their connection to neighboring Zn
2+
cations (
a
). Color code: Zn, O, and N atoms are represented as
cyan, red, and deep blue spheres, respectively, whereas C atoms are depicted as grey sticks.
Within the {Zn
II2
[(S,S)-serimox]} moieties, each Zn(II) metal ion results in a highly
distorted pyramidal coordination being linked by nitrogen and oxygen atoms from the
serimox ligand [Zn-N 1.985(4)Å and Zn-O
ser
ranging from 1.958(3) to 2.215(4) Å] and
a terminal water molecule [Zn-O
water
2.011(4) Å] (Figure 2b). The 3D network features
two types of small pore, different in size and shape, propagating along the band caxes
(
Figure 3
, Figures S2 and S3). Hydrophilic square sized pores (Figure 3a, left and Figure S3)
and hydrophilic irregular pores of medium size (virtual diameters of ca. 0.30 and 0.40 nm,
respectively) (Figure 3a, right and Figure S2) are decorated by the primary alcohol group
of serine moieties, pointing inwards towards the voids, and accountable for its resulting
host–guest chemistry.

Molecules 2021,26, 4098 3 of 9
Figure 3.
Perspective views of the porous networks of 1 (
a
) and CO
2
@1 (
b
) along the c(
left
) and
b(
right
) axes. Color code: Zn atoms and C and O from guest CO
2
molecules are represented as
cyan, grey, and red spheres, whereas serimox ligands—with the exception of serine residues—are
represented by grey sticks. –CH
2
OH groups and N atoms are represented as cyan, red, and deep
blue spheres, respectively, whereas C atoms are depicted as grey sticks.
Crystals of 1, left in a sealed glass tube containing an aqueous solution of BG dye for
one week, after irradiation in the range 250–350 nm for 60 min were analyzed by SCXRD at
a temperature of 100 K and the crystal structure of CO
2
@1 was determined, revealing a
slight deformation of the framework—likely correlated to CO
2
adsorption process—but
still isomorphous to 1, crystallizing in the P4
1
2
1
2 space group. Adsorption of CO
2
gas—
produced by the photocatalytic process at 298 K—results in linear negative expansion.
Pores that run parallel to the c-axis contract upon CO
2
inclusion (
∆
a,
∆
b slightly < 0;
∆
c < 0;
∆
V < 0). The largest change in dimensions is observed for the caxis, accounting for a small
decrease in the unit–cell volume (∆V≈48 Å3, Table S1).
The crystal structure of the adsorbate CO
2
@1 clearly evidences the presence of CO
2
guest molecules hosted in the hydrophilic irregular pores of 1 (Figure 3b,
Figures S4 and S6
.
A primary adsorption site can be identified on the CO
2
molecule (Figure 4), where the
plane containing the ligands are situated at only 2.83(1) Å [distance between centroid of
oxamate core and C atom of CO
2
molecule] from the C atom of CO
2
molecules occupying
the primary site, suggesting an interaction between the C(
δ+
) atom of the CO
2
molecule and
the O lone pair of the oxamate core of the ligand, as observed before [
46
]. The described
guest molecule orientation generates a kind of
π
(CO
2
)
···π
(oxamate) dimer exhibiting
C(oxamate)
···
O(CO
2
) and C(CO
2
)
···
O(oxamate) symmetric contacts of 3.08(1) and 3.32(1)
Å, respectively. The secondary adsorption sites identified are situated at the center of the
pores, where CO2molecules are packed with closest contact with the framework through
the H
2
C- and HC- of the ligand [shortest O-C-O
····
H-C- at 2.04(3) and 2.09(3) Å, for H
2
C-
and HC- fragments, respectively] (Figure 4, Figures S4 and S5). The alcoholic fragment
makes a contribution as well, being situated very close to CO
2
molecules [O-C-O
···
H-O-
and HO
···
O-C-O at 2.11(6) and 2.63(3) Å, respectively]. Despite the supposed flexibility
and structural adaptability that serine residues could offer, no important differences in the
alcoholic chain conformations have been observed in the CO
2
@1 adsorbate with respect
to 1, where only Zn-O
ser
[ranging from 1.935(3) to 2.191(4) Å] distances show a slight

Molecules 2021,26, 4098 4 of 9
contraction with respect to 1, while Zn-O
water
[1.992(4) Å], and Zn-N bond lengths [1.959(4)
Å] fall in the range of the expected values for Zn(II) metal ions [47].
Figure 4.
Details of CO
2
@1 crystal structure showing the adsorption sites identified for CO
2
adsorbed
molecules. Color code as in Figure 3.
What is worth underlining is the unusual penta-coordination of Zn(II) ions observed
in 1 and CO
2
@1, reminiscent (in geometry) of that observed for the catalytic metal ions
of the di-zinc aminopeptidase from Aeromonas proteolytica (AAP) [
48
]. Surveys of the
Cambridge Structural Database (CSD) show zinc ion coordination number frequencies
of ca. 60% and 25% for 4 and 6 coordination numbers, respectively. Interestingly, the
zinc ion coordination prevalence in protein sites depends on whether the zinc plays a
structural or a catalytic role. In structural zinc sites, the occurrence rate for 4, 5, and 6
coordination numbers is 80%, 6%, and 12%, respectively; whereas in catalytic zinc sites,
the occurrence rate for 4, 5, and 6 coordination is 47%, 45%, and 6%, respectively [
49
].
Thus, five coordinate, or geometrically strained zinc sites, may represent sites equipped for
catalysis, whereas four coordinate ideal tetrahedral zinc sites may represent stable sites
affiliated with structural support.
Single-crystal X-ray experiment on samples of 1 after irradiation with UV light (with-
out BG dye) do not show the presence of CO
2
molecules, just coordinated water and small
voids with light diffuse electron density. This ruled out the possibility of CO
2
adsorp-
tion from air or solvent in 1, and reinforced our hypothesis that CO
2
@1 comes from the
decomposition of the BG dye.
The experimental powder X-ray diffraction (PXRD) pattern of a polycrystalline sample
of 1 is shown in Figure 5. It is consistent with the theoretical one and confirms the
purity and homogeneity of the bulk sample. The solvent contents were determined by
thermogravimetric analysis (TGA) under a dry N
2
atmosphere (see Figure S7, Supporting
Information) and helped to established the final chemical formula. Attempts to activate 1
(under different protocols) for measuring N
2
isotherms proved unsuccessful, most likely
related to its loss of structural stability when all molecule solvents were removed.
The photocatalytic activity of MOF 1 for the degradation of BG dye was then inves-
tigated. For this purpose, 25 mg of 1 were suspended in 50 mL of a 10 ppm aqueous
solution of BG. Prior to irradiation, the mixture was kept in the dark for 30 min to verify
that degradation only occurs under irradiation. After that period, the suspension started to
be irradiated, under mild stirring at 250 nm. At different times (5, 15, 30, 60, and 120 min),
1 mL aliquots were taken, centrifuged, and diluted, and their UV–Vis absorption spectra
were registered (Figure 6a). An identical experiment was performed, under the same
conditions, in the absence of 1 (Figure S8). In order to have a better characterization of 1,
we performed UV-Vis diffuse reflectance spectroscopy, which revealed a strong adsorption
band below 350 nm (Figure S9).

Molecules 2021,26, 4098 5 of 9
Figure 5.
Calculated (
a
) and experimental (
b
) PXRD patterns of 1 in the 2
θ
range 2.0–60.0
◦
at R.T.
(
c
) Experimental PXRD pattern of 1 after three consecutive cycles of photocatalytic degradation of BG.
Figure 6.
(
a
) Evolution with time of the UV-Vis absorption spectra of 10 ppm solutions of brilliant
green in water in the presence of 25 mg of a polycrystalline sample of 1. Blue: t= 0; Red: t= 5 min.;
Green: t= 15 min.; Orange = 30 min.; Yellow: t= 60 min.; Purple: t= 120 min. The inset shows the
BG solutions at t = 0 min. (left) and 120 min. (right) of exposure of the BG solution with MOF 1.
(
b
) Kinetic profile of the degradation of brilliant green under irradiation at 250 nm in the presence of
MOF 1 (blue) and with no photocatalyst (red).
Figure 6shows the photodegradation efficiency of 1 towards BG. Such efficiency was
evaluated by measuring the decrease in the characteristic absorption bands of BG dye,
which appear at 420 nm and 625 nm, respectively. Thus, under irradiation in the presence of
1, it a gradual decrease of both peaks with time can be observed, until the vanish completely
after 120 min (Figure 6a), which indicates that 100% of BG dye is eliminated after that time
(Figure 6b). In turn, the same experiment, in the absence of 1, (Figure S8 and Figure 6b),

Molecules 2021,26, 4098 6 of 9
shows a very smooth decrease of the UV–Vis absorption bands, confirming the key role
of 1 as photocatalyst. Tauc plot of the Kubelka–Munk function (Figure S10) allowed us to
obtain an estimation of the optical band of 1 (3.03 eV), which evidenced the suitability of
it to perform the degradation of BG. Moreover, the reuse capability of 1 was stablished
by both UV–Vis and PXRD experiments. On the one hand, two more UV–Vis vs. time
experiments were carried out, using 1 as photocatalyst, with identical results (Figure S11),
confirming that 1 can be employed in at least 3 cycles. On the other hand, PXRD patterns
of 1 after three cycles are identical to those of the synthesized material suggesting that no
degradation occurs during the photocatalytic process (Figure 5c).
The full degradation of the organic dye was also supported by thermogravimetric
analysis coupled with mass spectrometry (TGA-MS) on CO
2
@1 (Figure S12). The weight
loss in TGA led to two peaks in MS spectra with the mass to charge ratio (m/z) of 18
and 44, which can be attributed to water and carbon dioxide. However, the amount of
CO
2
desorbed was lower than that obtained from X-ray crystallography. Most likely,
this is related to some losses of CO
2
during the handling of the measurement itself. The
larger size of brilliant green dye compared to 1 pore size precluded the adsorption of the
organic dye on MOF channels to perform the photocatalytic event. Thus, the photocatalytic
activity of 1 most likely will arise from the crystal surface. With the aim of confirming the
photodegradation’s occurrance at the surface of 1, we measured the evolution of the BG
concentration in solution when it is put in contact with 1 during 30 min in the dark. As
can be observed in Figure S13, there is no appreciable difference in the BG concentration
in solution, which supports our hypothesis. A leaching test ruled out the possibility
of decomposition products of Zn-based MOF being responsible for the photocatalytic
degradation of brilliant green. This was also supported, in an indirect manner, by the
maintenance of both the activity in the recyclability studies (Figure S11) and the high
crystallinity of PXRD diffraction patterns after the photocatalytic process (Figure S5c).
A plausible mechanism for the degradation of BG dye is shown in Scheme S1. With
the aid of UVC light, 1 generates electron and hole pairs. While the electrons jump to the
conducting band, the holes remain in the valence band. The holes were scavenged by water
molecules leading to energetically reactive hydroxyl radicals, and the photogenerated
electrons react with O
2
to produce the superoxide radical anions of oxygen. From them,
based on literature precedents [
50
–
53
], the OH
•
is believed to be the dominant oxidizing
agent for the mineralization of BG dye into CO
2
and H
2
O.
1
H NMR of solutions after
photocatalytic experiment do not show any peaks (apart from H
2
O) that can be attributed
to any known intermediate from a previously reported study.
55
With the aim of exploring
the formation of intermediate species, we performed liquid chromatography/tandem mass
spectrometry (LC-MS/MS) on solutions after 30 min. of UV irradiation, where we were
able to identify four degradation molecules (Scheme S2) [54].
3. Conclusions
In summary, we have reported a novel, eco-friendly Zn-based MOF with the formula
{Zn
2
[(S,S)-serimox](H
2
O)
2
]
···
H
2
O (1) and its performance as a photocatalyst of BG aque-
ous solutions. This MOF with good water stability was able to efficiently photodegrade
10 ppm aqueous solutions of BG in 120 min. Indeed, UV-Vis spectroscopy measurements of
irradiated solutions, with and without the presence of 1, clearly revealed the photodegra-
dation role of the framework. Single-crystal X-ray crystallography was applied not only to
structurally characterize the pristine structure of 1, but more interestingly, after the photo-
catalytic process. The resolution of the crystal structure of CO
2
@1 allowed us to confirm
the total degradation of the dye and the presence of CO
2
molecules (from the degradation
process) retained within the irregular hydrophilic channels of 1. Reusability tests of 1, with
up to 3 cycles of the photodegradation process, evidenced structural and performance
robustness, which further confirms the viability of 1 as an efficient photocatalyst. Our
current work is focused on extending this study to other Zn-based MOFs derived from
natural amino acids.

Molecules 2021,26, 4098 7 of 9
Supplementary Materials:
The following are available online at, experimental preparation, analytical
and spectroscopic characterization of 1, and additional Figures S1–S13, Table S1, Schemes S1 and S2.
Author Contributions:
Conceptualization, D.A., E.P. and J.F.-S.; methodology, P.E., M.V.-C. and R.B.;
formal analysis, D.A., E.P. and J.F.-S.; investigation, P.E., M.V.-C. and R.B.; writing—original draft
preparation, P.E., M.V.-C. and R.B.; writing—review and editing, D.A., E.P. and J.F.-S.; supervision,
D.A., E.P. and J.F.-S.; project administration, D.A., E.P. and J.F.-S.; funding acquisition, D.A., E.P. and
J.F.-S.. All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement:
CCDC 2062289-2062290 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/
cif (accessed on 3 July 2021), or by emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44-1223-
336033.
Acknowledgments:
This work was supported by the Ministero dell’Istruzione, dell’Universitàe
della Ricerca (Italy) and the MINECO (Spain) (Projects PID2019
−
104778GB
−
I00 and Excellence
Unit “Maria de Maeztu” CEX2019
−
000919
−
M). R. B. thanks the MIUR (Project PON R&I FSE–FESR
2014–2020) for the predoctoral grant. D.A. acknowledges the financial support of the Fondazione
CARIPLO/“Economia Circolare: ricerca per un futuro sostenibile” 2019, project code: 2019–2090,
MOCA. E.P. acknowledges the financial support of the European Research Council under the Euro-
pean Union’s Horizon 2020 research and innovation programme/ERC Grant Agreement No 814804,
MOF–reactors. Thanks are also extended to the “2019 Post–doctoral Junior Leader–Retaining Fel-
lowship, la Caixa Foundation (ID100010434 and fellowship code LCF/BQ/PR19/11700011” and
“Subvenciones concedidas a la excelencia científica de juniors investigadores, SEJI/2020/034“ (J. F.–
S.). We would like to thank Antonio Leyva-Pérez and Alejandro Vidal-Moya (Instituto de Tecnología
Química, Universidad Politècnica de València-Consejo Superior de Investigaciones Científicas) for
their help with solid-state 13C NMR experiments.
Conflicts of Interest: The authors declare no conflict of interest.
Sample Availability: Samples of compounds 1 is available from the authors.
References
1.
U.S. Environmental Protection Agency. 2012 ed. of the Drinking Water Standards and Health Advisories. 2012. Available online:
https://rais.ornl.gov/documents/2012_drinking_water.pdf (accessed on 10 June 2021).
2.
United Nations. Transforming Our World: The 2030 Agenda for Sustainable Development. 2015. Available online: https:
//sustainabledevelopment.un.org/post2015/transformingourworld (accessed on 10 June 2021).
3.
Yagub, M.T.; Sen, T.K.; Afroze, S.; Ang, H.M. Dye and its removal from aqueous solution by adsorption: A review. Adv. Colloid.
Interface Sci. 2014,209, 172–184. [CrossRef]
4.
Ahmad, A.; Mohd-Setapar, S.H.; Chuong, C.S.; Khatoon, A.; Wani, W.A.; Kumar, R.; Rafatullah, M. Recent advances in new
generation dye removal technologies: Novel search for approaches to reprocess wastewater. RSC Adv.
2015
,5, 30801–30818.
[CrossRef]
5.
Yang, Z.; Wang, F.; Zhang, C.; Zeng, G.; Tan, X.; Yu, Z.; Zhong, Y.; Wang, H.; Cui, F. Utilization of LDH-based materials as
potential adsorbents and photocatalysts for the decontamination of dyes wastewater: A review. RSC Adv.
2016
,6, 79415–79436.
[CrossRef]
6.
Gupta, N.K.; Ghaffari, Y.; Kim, S.; Bae, J.; Kim, K.S.; Saifuddin, M. Photocatalytic Degradation of Organic Pollutants over MFe
2
O
4
(M = Co, Ni, Cu, Zn) Nanoparticles at Neutral pH. Sci. Rep. 2020,10, 4942. [CrossRef] [PubMed]
7.
Dias, E.M.; Petit, C. Towards the use of metal–organic frameworks for water reuse: A review of the recent advances in the field of
organic pollutants removal and degradation and the next steps in the field. J. Mater. Chem. A 2015,3, 22484–22506. [CrossRef]
8.
Mon, M.; Bruno, R.; Ferrando-Soria, J.; Armentano, D.; Pardo, E. Metal-Organic Framework Technologies for Water Remediation:
Towards a Sustainable Ecosystem. J. Mater. Chem. A 2018. [CrossRef]
9.
Tiburcio, E.; Greco, R.; Mon, M.; Ballesteros-Soberanas, J.; Ferrando-Soria, J.; López-Haro, M.; Hernández-Garrido, J.C.; Oliver-
Meseguer, J.; Marini, C.; Boronat, M.; et al. Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-,
and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids. J. Am. Chem. Soc. 2021,143, 2581–2592. [CrossRef]

Molecules 2021,26, 4098 8 of 9
10.
Wang, Q.; Gao, Q.; Al-Enizi, A.M.; Nafady, A.; Ma, S. Recent advances in MOF-based photocatalysis: Environmental remediation
under visible light. Inorg. Chem. Front. 2020,7, 300–339. [CrossRef]
11.
Rojas, S.; Horcajada, P. Metal–Organic Frameworks for the Removal of Emerging Organic Contaminants in Water. Chem. Rev.
2020,120, 8378–8415. [CrossRef]
12.
Jiang, D.; Chen, M.; Wang, H.; Zeng, G.; Huang, D.; Cheng, M.; Liu, Y.; Xue, W.; Wang, Z. The application of different typological
and structural MOFs-based materials for the dyes adsorption. Coord. Chem. Rev. 2019,380, 471–483. [CrossRef]
13.
Parmar, B.; Bisht, K.K.; Rajput, G.; Suresh, E. Recent advances in metal–organic frameworks as adsorbent materials for hazardous
dye molecules. Dalt. Trans. 2021,50, 3083–3108. [CrossRef]
14.
Furukawa, H.; Cordova, K.E.; O’Keeffe, M.; Yaghi, O.M. The Chemistry and Applications of Metal-Organic Frameworks. Science
2013,341, 974. [CrossRef]
15.
Maurin, G.; Serre, C.; Cooper, A.; Férey, G. The new age of MOFs and of their porous-related solids. Chem. Soc. Rev.
2017
,46,
3104–3107. [CrossRef] [PubMed]
16.
Kitagawa, S.; Matsuda, R. Chemistry of coordination space of porous coordination polymers. Coord. Chem. Rev.
2007
,251,
2490–2509. [CrossRef]
17. Férey, G. Hybrid porous solids: Past, present, future. Chem. Soc. Rev. 2008,37, 191–214. [CrossRef] [PubMed]
18. Long, J.R.; Yaghi, O.M. The pervasive chemistry of metal-organic frameworks. Chem. Soc. Rev. 2009,38, 1213–1214. [CrossRef]
19.
Farha, O.K.; Hupp, J.T. Rational Design, Synthesis, Purification, and Activation of Metal
−
Organic Framework Materials. Acc.
Chem. Res. 2010,43, 1166–1175. [CrossRef]
20.
Cui, Y.; Li, B.; He, H.; Zhou, W.; Chen, B.; Qian, G. Metal–Organic Frameworks as Platforms for Functional Materials. Acc. Chem.
Res. 2016,49, 483–493. [CrossRef] [PubMed]
21.
Kirchon, A.; Feng, L.; Drake, H.F.; Joseph, E.A.; Zhou, H.-C. From fundamentals to applications: A toolbox for robust and
multifunctional MOF materials. Chem. Soc. Rev. 2018,47, 8611–8638. [CrossRef] [PubMed]
22.
Jaramillo, D.E.; Reed, D.A.; Jiang, H.Z.H.; Oktawiec, J.; Mara, M.W.; Forse, A.C.; Lussier, D.J.; Murphy, R.A.; Cunningham, M.;
Colombo, V.; et al. Selective nitrogen adsorption via backbonding in a metal–organic framework with exposed vanadium sites.
Nat. Mater. 2020,19, 517–521. [CrossRef]
23.
Farha, O.K.; Eryazici, I.; Jeong, N.C.; Hauser, B.G.; Wilmer, C.E.; Sarjeant, A.A.; Snurr, R.Q.; Nguyen, S.T.; Yazaydın, A.Ö.;
Hupp, J.T. Metal–Organic Framework Materials with Ultrahigh Surface Areas: Is the Sky the Limit? J. Am. Chem. Soc.
2012
,134,
15016–15021. [CrossRef] [PubMed]
24.
Gonzalez, M.I.; Turkiewicz, A.B.; Darago, L.E.; Oktawiec, J.; Bustillo, K.; Grandjean, F.; Long, G.J.; Long, J.R. Confinement of
atomically defined metal halide sheets in a metal–organic framework. Nature 2020,577, 64–68. [CrossRef] [PubMed]
25.
Mon, M.; Bruno, R.; Sanz-Navarro, S.; Negro, C.; Ferrando-Soria, J.; Bartella, L.; di Donna, L.; Prejanò, M.; Marino, T.; Leyva-Pérez,
A.; et al. Hydrolase–like catalysis and structural resolution of natural products by a metal–organic framework. Nat. Commun.
2020,11, 3080. [CrossRef] [PubMed]
26.
Bloch, W.M.; Champness, N.R.; Doonan, C.J. X-ray Crystallography in Open-Framework Materials. Angew. Chemie Int. Ed.
2015
,
54, 12860–12867. [CrossRef]
27. Rissanen, K. Crystallography of encapsulated molecules. Chem. Soc. Rev. 2017,46, 2638–2648. [CrossRef]
28.
Inokuma, Y.; Arai, T.; Fujita, M. Networked molecular cages as crystalline sponges for fullerenes and other guests. Nat. Chem.
2010,2, 780–783. [CrossRef]
29.
Young, R.J.; Huxley, M.T.; Pardo, E.; Champness, N.R.; Sumby, C.J.; Doonan, C.J. Isolating reactive metal-based species in
Metal–Organic Frameworks – viable strategies and opportunities. Chem. Sci. 2020,11, 4031–4050. [CrossRef] [PubMed]
30.
Bloch, W.M.; Burgun, A.; Coghlan, C.J.; Lee, R.; Coote, M.L.; Doonan, C.J.; Sumby, C.J. Capturing snapshots of post-synthetic
metallation chemistry in metal–organic frameworks. Nat. Chem. 2014,6, 906–912. [CrossRef] [PubMed]
31.
Viciano-Chumillas, M.; Mon, M.; Ferrando-Soria, J.; Corma, A.; Leyva-Pérez, A.; Armentano, D.; Pardo, E. Metal–Organic
Frameworks as Chemical Nanoreactors: Synthesis and Stabilization of Catalytically Active Metal Species in Confined Spaces. Acc.
Chem. Res. 2020,53, 520–531. [CrossRef]
32.
Burgun, A.; Coghlan, C.J.; Huang, D.M.; Chen, W.; Horike, S.; Kitagawa, S.; Alvino, J.F.; Metha, G.F.; Sumby, C.J.; Doonan, C.J.
Mapping-Out Catalytic Processes in a Metal-Organic Framework with Single-Crystal X-ray Crystallography. Angew. Chemie Int.
Ed. 2017,56, 8412–8416. [CrossRef]
33.
Kobielska, P.A.; Howarth, A.J.; Farha, O.K.; Nayak, S. Metal–organic frameworks for heavy metal removal from water. Coord.
Chem. Rev. 2018,358, 92–107. [CrossRef]
34.
Gao, Q.; Xu, J.; Bu, X.-H. Recent advances about metal–organic frameworks in the removal of pollutants from wastewater. Coord.
Chem. Rev. 2019,378, 17–31. [CrossRef]
35.
Mon, M.; Bruno, R.; Tiburcio, E.; Viciano-Chumillas, M.; Kalinke, L.H.G.; Ferrando-Soria, J.; Armentano, D.; Pardo, E. Multivariate
Metal–Organic Frameworks for the Simultaneous Capture of Organic and Inorganic Contaminants from Water. J. Am. Chem. Soc.
2019,141, 13601–13609. [CrossRef] [PubMed]
36.
Sharma, V.K.; Feng, M. Water depollution using metal-organic frameworks-catalyzed advanced oxidation processes: A review. J.
Hazard. Mater. 2017. [CrossRef]
37.
Wu, Z.; Yuan, X.; Zhang, J.; Wang, H.; Jiang, L.; Zeng, G. Photocatalytic Decontamination of Wastewater Containing Organic Dyes
by Metal-Organic Frameworks and their Derivatives. ChemCatChem 2017,9, 41–64. [CrossRef]

Molecules 2021,26, 4098 9 of 9
38.
Zeng, L.; Guo, X.; He, C.; Duan, C. Metal–Organic Frameworks: Versatile Materials for Heterogeneous Photocatalysis. ACS Catal.
2016,6, 7935–7947. [CrossRef]
39.
Wang, C.-C.; Li, J.-R.; Lv, X.-L.; Zhang, Y.-Q.; Guo, G. Photocatalytic organic pollutants degradation in metal–organic frameworks.
Energy Environ. Sci. 2014,7, 2831–2867. [CrossRef]
40.
Zhang, T.; Lin, W. Metal–organic frameworks for artificial photosynthesis and photocatalysis. Chem. Soc. Rev.
2014
,43, 5982–5993.
[CrossRef] [PubMed]
41.
Chimupala, Y.; Phromma, C.; Yimklan, S.; Semakul, N.; Ruankham, P. Dye wastewater treatment enabled by piezo-enhanced
photocatalysis of single-component ZnO nanoparticles. RSC Adv. 2020,10, 28567–28575. [CrossRef]
42.
Tian, C.; Zhang, Q.; Wu, A.; Jiang, M.; Liang, Z.; Jiang, B.; Fu, H. Cost-effective large-scale synthesis of ZnO photocatalyst with
excellent performance for dye photodegradation. Chem. Commun. 2012,48, 2858. [CrossRef]
43.
Dong, J.-P.; Shi, Z.-Z.; Li, B.; Wang, L.-Y. Synthesis of a novel 2D zinc(II) metal–organic framework for photocatalytic degradation
of organic dyes in water. Dalt. Trans. 2019,48, 17626–17632. [CrossRef] [PubMed]
44.
Zhang, C.; Ma, D.; Zhang, X.; Ma, J.; Liu, L.; Xu, X. Preparation, structure and photocatalysis of metal-organic frameworks
derived from aromatic carboxylate and imidazole-based ligands. J. Coord. Chem. 2016,69, 985–995. [CrossRef]
45.
Jing, H.-P.; Wang, C.-C.; Zhang, Y.-W.; Wang, P.; Li, R. Photocatalytic degradation of methylene blue in ZIF-8. RSC Adv.
2014
,4,
54454–54462. [CrossRef]
46.
Mon, M.; Bruno, R.; Tiburcio, E.; Grau-Atienza, A.; Sepúlveda-Escribano, A.; Ramos-Fernandez, E.V.; Fuoco, A.; Esposito,
E.; Monteleone, M.; Jansen, J.C.; et al. Efficient Gas Separation and Transport Mechanism in Rare Hemilabile Metal–Organic
Framework. Chem. Mater. 2019,31, 5856–5866. [CrossRef]
47.
Rufino-Felipe, E.; Caballero-Jiménez, J.; Guerrero-Ramírez, L.-G.; Flores-Álamo, M.; Muñoz-Hernández, M.-Á. Novel hexanuclear
and octanuclear zinc alkyl cages derived from a bis-oxamidate ligand. Inorg. Chem. Commun. 2016,63, 107–110. [CrossRef]
48.
Desmarais, W.T.; Bienvenue, D.L.; Bzymek, K.P.; Holz, R.C.; Petsko, G.A.; Ringe, D. The 1.20 Å Resolution Crystal Structure of the
Aminopeptidase from Aeromonas proteolytica Complexed with Tris. Structure 2002,10, 1063–1072. [CrossRef]
49.
Ataie, N.J.; Hoang, Q.Q.; Zahniser, M.P.D.; Tu, Y.; Milne, A.; Petsko, G.A.; Ringe, D. Zinc Coordination Geometry and Ligand
Binding Affinity: The Structural and Kinetic Analysis of the Second-Shell Serine 228 Residue and the Methionine 180 Residue of
the Aminopeptidase from Vibrio proteolyticus. Biochemistry 2008,47, 7673–7683. [CrossRef] [PubMed]
50.
Sood, S.; Umar, A.; Mehta, S.K.; Sinha, A.S.K.; Kansal, S.K. Efficient photocatalytic degradation of brilliant green using Sr-doped
TiO2nanoparticles. Ceram. Int. 2015,41, 3533–3540. [CrossRef]
51.
Shanmugam, N.; Sathya, T.; Viruthagiri, G.; Kalyanasundaram, C.; Gobi, R.; Ragupathy, S. Photocatalytic degradation of brilliant
green using undoped and Zn doped SnO
2
nanoparticles under sunlight irradiation. Appl. Surf. Sci.
2016
,360, 283–290. [CrossRef]
52.
Migliorini, F.L.; Steter, J.R.; Rocha, R.S.; Lanza, M.R.V.; Baldan, M.R.; Ferreira, N.G. Efficiency study and mechanistic aspects in
the Brilliant Green dye degradation using BDD/Ti electrodes. Diam. Relat. Mater. 2016,65, 5–12. [CrossRef]
53.
Kaur, S.; Sharma, S.; Umar, A.; Singh, S.; Mehta, S.K.; Kansal, S.K. Solar light driven enhanced photocatalytic degradation of
brilliant green dye based on ZnS quantum dots. Superlattices Microstruct. 2017,103, 365–375. [CrossRef]
54.
Rehman, F.; Sayed, M.; Khan, J.A.; Shah, N.S.; Khan, H.M.; Dionysiou, D.D. Oxidative removal of brilliant green by UV/S
2
O
82-
,
UV/HSO
5−
and UV/H
2
O
2
processes in aqueous media: A comparative study. J. Hazard. Mater.
2018
,357, 506–514. [CrossRef]
[PubMed]