Fluorescence detection of aromatic amines and photocatalytic degradation of rhodamine B under UV light irradiation by luminescent metal-organic frameworks

Article abstract of DOI:10.1039/c4nj02356k

The detection of trace amounts of aromatic amines is significantly important for security concerns and pollution control. Two multifunctional metal-organic frameworks (MOFs), [ZnL·H₂O]_n (1) and [CdL·H₂O]_n·2nH

Full text of DOI:10.1039/c4nj02356k

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: F. Wang, C.
Dong, C. Wang, Z. Yu, S. Guo, Z. Wang, Y. Zhao and G. Li, New J. Chem., 2015, DOI:
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/njc

Page 1 of 18
New Journal of Chemistry
View Article Online
Fluorescence Detection of Aromatic Amines and PhotocatDaOlIy: 1t0i.1c039/C4NJ02356K
Degradation of Rhodamine B under UV light irradiation by
Luminescent Metal-Organic Frameworks
Fengqin Wang [a] *, Caifu Dong [a], Chengmiao Wang [a], Zongchao Yu [a], Shukun Guo [b],
Zechuan Wang [a], Yongnan Zhao [b], Guodong Li [c]
aCollege of Environmental and Chemical Engineering & Key Lab of Hollow Fiber Membrane
Materials & Membrane Process, Tianjin Polytechnic University, Tianjin 300387, China
bSchool of Materials Science and Engineering & Tianjin Key Lab of Fiber Modification and
Functional Fiber, Tianjin Polytechnic University, Tianjin 300387, China
cThe State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin
University,130023, China
E-mail: wangfengqin@tjpu.edu.cn Tel: (+86)-22-83955457
Abstract: Detection of trace amounts of aromatic amines is significantly important
for security concerns and pollution control. Two multifunctional metal-organic
frameworks (MOFs), [ZnL·H2O]n (1) and [CdL·H2O]n·2nH2O (2) (L
=
5-aminoisophthalic acid), were strategically chosen to utilize for the detection of
aromatic amines pollutants. The fluorescent experiments show that the two MOFs can
selectively detect aromatic amines with high sensitivity. Among the given analytes,
p-nitroaniline, an electron-deficient analyte, significantly quenched the fluorescence
intensities of 1 and 2. In contrast, other aromatic amines enhanced the fluorescence
intensities of 1 and 2 to some extents. Particularly, diphenylamine gives the most
apparent enhancement effect than those of others under the same experimental
conditions. Meanwhile, the photocatalytic activities of the two MOFs were also
determined by UV light induced photodegradation of Rhodamine B (RhB)
experiments. All the results indicate that the studied complexes are stable and good
candidates for both heterogeneous photocatalyst and aromatic amines detectable
materials.
Keywords: Luminescent Metal-Organic complexes; Fluorescence detection;
Aromatic amines; Photocatalytic;
1

New Journal of Chemistry
Page 2 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
1. Introduction
Aromatic amines, known as notorious environmental pollutants, are often released
into the environment from chemical, textile and leather industries along with wastes
and from the decomposition of azo-dyes in various daily necessities. 1 The exposure
to aromatic amines even at very low concentrations is suspected to result in
carcinogenicity by ingestion, inhalation and skin contact. 2–4 Therefore, the detection
of aromatic amines is a growing concern for both security reasons and pollution
control. Up to now, various techniques have been developed for detection of
aromatic amines, such as chromatographic, 5–7 electrophoretic methods 8–10 and mass
spectrometric detector (GC–MS) 11–13. Although these documented methods worked
well in the aromatic amine detection, most of them suffered from drawbacks of
expensive instrumentation, complicated operation and time-consuming procesure,
which made them unsuitable for on-site, quick detection. 14 The development of
sensitive analytical method for rapid and efficient detection of aromatic amines is
therefore not only an exigent requirement in the field of public security, but also
critical for environmental protection.
Fluorescence sensing has been proven to be an alternative analytical technology
for detecting aromatic amines based on fluorescence quenching or enhancement
effect. In this respect, metal-organic frameworks (MOFs), as a new kind of
fluorescence sensing materials, have attracted enormous attention for sensing
applications due to their high interfacial surface area and tunable pore structures.
15–17 Generally, MOF-based sensing materials are usually constructed with aromatic
ligands because the π electron systems of the ligands endow the MOFs with
photoluminescence properties and provide potential supramolecular recognition sites
for hydrogen bonds, π-π stacking and electrostatic interaction between their
backbones and the analytes. 18–19 Such interactions lead to effective charge or energy
transfer process between the analytes and the MOFs, which concenquently triggers
the fluorescence response upon interaction, such as the variation in emission
intensity or wavelength shift. 20 By using MOFs as the sensing materials, up-to-date,
2

Page 3 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
some documented examples have demonstrated the detection of nitroaromatic
compounds through the effective interactions between the analytes and the MOF
skeletons. 14, 21–25 Although it is still scarce on fluorescence sensing aromatic amines,
26–29
the construction of luminescent MOFs for rapid and efficient detection of
aromatic amines is of great significance for environmental monitoring.
Besides the detection of pollutants, on the other hand, MOFs have also attracted
much attention for their applications as photocatalyst in decomposing organic
contaminations because of their high surface areas and high light absorption abilities.
30–33 In general, MOFs with absorption bands in the UV region exhibit photocatalytic
performance for degrading organic dyes upon UV light excitation. Recently, some
literatures have reported sensing applications as well as heterogeneous
30, 34
photodegradation of organic dyes.
Thus, it is highly necessary to construct
multifunctional MOFs with both sensing behaviors and photocatalytic properties by
the assembly of aromatic ligands and functional metal centers.
In this work, we selected 5-aminoisophthalic acid, which was widely used to
35-39
construct MOFs with d10 metal ions,
as the organic linker to synthesize two
MOFs, [ZnL·H2O]n (1) and [CdL·H2O]n·2nH2O (2) (L = 5-aminoisophthalic acid),
which structures are well documented. 35, 36 However, the applications of them in the
fluorescence sensing and photocatalysis have not yet been reported. Herein, the
fluorescence sensing performances and the photocatalytic activities of these two
MOFs are systematically studied. The results indicate that complexes 1 and 2 are
promising luminescent probes for detecting aromatic amines via fluorescence
enhancement or quenching effect, which can be potentially used for pollutants
detection or environmental monitoring. In addition, compounds 1 and 2 also exhibit
excellent photocatalytic activities for degrading organic dyes under UV light
irradiation.
2. Experimental
2.1 Materials and methods
All reagents were obtained from commercial sources and used as received.
3

New Journal of Chemistry
Page 4 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
Infrared spectra were recorded on a BIO-RAD FTS3000 system by using KBr pellets
in the range 4000 − 400 cm-1. Elemental analyses (C, H and N) were measured on a
Perkin-Elmer auto-analyzer. Thermogravimetric (TG) analysis was carried out on a
Netzsch STA 409 PG/PC analyzer at a heating rate of 5 °C min-1 from ambient
temperature to 800 °C. Powder X-ray diffraction (PXRD) data were recorded on a
D/MAX-2500 automated diffractometer. The simulated PXRD patterns were derived
from the single crystal data through the diffraction-crystal module of the Mercury
program version 3.0. The photoluminescence spectra of the studied complexes in
solid and their samples in acetonitrile or methanol were measured on an F−380
Spectrophotometer. The UV-vis adsorption spectra were recorded by using an
Evolution 201 UV-Vis Spectrometer. The solid-state diffuse-reflectance spectra for
powder samples were recorded on a U-4100 Spectrophotometer spectrometer
equipped with an integrating sphere by using BaSO4 as a white standard.
2.2 Synthesis of [ZnL·H2O]n (1) and [CdL·H2O]n·2nH2O (2)
Homogenized mixtures of L (18.1 mg, 0.1 mmol), Zn(NO3)2·6H2O (29.7 mg, 0.1
mmol), DMF (4 mL) and H2O (4 mL) were sealed in a 25 mL stainless steel vessel
and heated at 85 °C for 3 days under autogenous pressure, and then cooled to room
temperature. Colorless block crystals of 1 were obtained by filtration. Elemental
analysis (%) calcd for C8H7NO5Zn: C, 36.57; H, 2.67; N, 5.33. Found: C, 36.23; H,
2.49; N, 5.63. IR spectra (KBr pellet cm-1): 3442 br, 1622 vs, 1566 vs, 1478 w, 1414
m, 1367 vs, 1157 m, 966 w, 737 m. Complex 2 was obtained by a procedure similar to
that for 1 but only changing the Zn(NO3)2·6H2O with CdCl2·2.5H2O. Colorless block
crystals were obtained by filtration. Elemental analysis (%) calcd for C8H11NO7Cd: C,
27.78; H, 3.18; N, 4.05. Found: C, 28.05; H, 3.51; N, 4.16. IR spectra (KBr pellet
cm-1): 3478 br, 1614 vs, 1566 vs, 1474 w, 1373 vs, 1098 w, 1018 w, 808 w, 767 m.
2.3 Fluorescence titrations in dispersed medium
The fluorescence spectra of compounds 1 and 2 were measured by dispersing
grounded sample (3 mg) in acetonitrile (3 mL) or methanol (3 mL), respectively,
which were treated by ultrasonication for 1.5 h. All titrations were carried out by
gradually adding analytes in an incremental fashion. The corresponding fluorescence
4

Page 5 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
emission spectra were recorded at 298 K. Each titration was repeated several times to
get concordant values. For all measurements, the suspensions of 1 and 2 were
excited at λex = 310 nm and the corresponding emission wavelengths were monitored
from 320 to 600 nm. The fluorescence efficiency was calculated by using the
formula [(F0-F)/F0] × 100% (F0 is the initial fluorescence intensity).
2.4 Photocatalytic experiments
Photocatalytic experiments in aqueous solutions were performed in a 150 mL
quartz beaker. A 300 W high-pressure mercury lamp was used as the UV light
source. An aqueous solution of RhB (80 mL) with a concentration of 10-5 mol L-1
was mixed with the catalysts (20 mg) and illuminated. Before turning on the lamp,
the suspension containing RhB and the photocatalyst was magnetically stirred in the
dark for 40min until an adsorption-desorption equilibrium was established. At given
irradiation intervals, a series of aqueous solutions of a certain volume were collected
and separated by centrifugation to remove suspended catalyst particles and then
subjected to UV/Vis spectroscopic measurements.
2.5 X-ray crystallography
Single crystal X−ray diffraction measurement for 1 and 2 were carried out on
computer-controlled RIGAKU diffractometer equipped with graphite-
monochromatized Mo-Kα radiation with a wavelength of 0.71073Å by using the
ω-scan technique. The structures were solved by direct methods and refined by
full-matrix least squares on F2 using the SHELXS 97 and SHELXL 97 programs. 40,
41
Semiempirical absorption corrections were applied using the SADABS program.
42
All non-hydrogen atoms were refined anisotropically. The hydrogen atoms were
generated geometrically and treated by a mixture of independent or constrained
refinement. The crystallographic data for 1 and 2 are listed in Table S1, selected
bond lengths (Å) and angles (°) are listed in Table S2. The hydrogen bonds data are
listed in Table S3.
3. Results and discussion
3.1 Structure description of 1
5

New Journal of Chemistry
Page 6 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
The single crystal X-ray diffraction structure determinations show that both
compounds 1 and 2 have 2D layer structures, which are the same as those in the
literatures. So, herein, we only describe the detailed structure of 1 as an example. In
the asymmetric unit of 1, there is only one crystallographically independent zinc ion.
The coordination environment is shown in Fig. 1. The zinc ion is four-coordinated
with two oxygen atoms and one nitrogen atom from three different L ligands, one
oxygen atom from one coordinated water molecule and displays a distorted
tetrahedral geometry. The Zn−O distances are in the range of 1.9570(16) − 1.9756
(15) Å. The Zn−N distance is 2.0363(18) Å.
Fig. 1 The coordination environment of the Zn (II) ion in 1 with 30% probability thermal
ellipsoids.
In the structure of compound 1, each L ligand adopts tri-monodentate mode with
its two carboxylate groups and one amino group coordinating to three different zinc
ions. Each zinc ion is linked by three L ligands to form an infinite 2D layer structure
containing a 22-membered macrocycle (Fig. 2). It is very interesting to see that, in
the same layer of 1, all of the coordinated water molecules are oriented toward the
same direction. Furthermore, all of these layers, where the coordinated water
molecules are oriented in opposite directions, are linked together in pairs through
strong hydrogen bonds into a three-dimensional supramolecular network.
Fig. 2 The 2D layer framework of 1
6

Page 7 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
The thermal stabilities of 1 and 2 were studied by thermogravimetric analysis
(TGA). The thermal decomposition process of 1 occurred in two steps (Fig. S1). The
first weight loss of 7.09% between 180 and 328 °C corresponded to the release of one
water molecule (calcd: 6.86%). A plateau was observed from 328 to 446°C, indicating
no further weight loss. When the temperature was above 446°C, the compound started
to decompose rapidly. The residue ZnO was obtained in 30.45% (calcd: 30.85%).
Powder X-ray diffraction analysis was further conducted to confirm the phase purity
of 1, which was shown in Fig. S2. For 2, the thermal decomposition process can be
described in three steps (Fig. S3). The first weight loss of 9.89% between 100 and 143
°C corresponded to the release of two free water molecules (calcd: 10.41%). The
second step lost a coordinated water molecule with the mass loss of 4.53% between
143 and 310°C (calcd: 5.21%). The third step mass loss began at 426°C and ended at
616°C with the product CdO formed in 37.91% (calcd: 37.15%). The PXRD pattern
of the as-synthesized sample of 2 is also very close to the simulated pattern from
single crystal structure (Fig. S4). This also demonstrates the phase purity of the as-
synthesized sample of 2.
3.2 The Photophysical Properties
The solid-state fluorescence spectra of 1 and 2 were recorded at room temperature.
As shown in Fig. S5 and S6, the main emission band of 1 located at 415 nm (λex =
310 nm) and that of 2 centered at 425 nm (λex = 310 nm). For the free ligand L, the
characteristic photoluminescence emission maxima located at 467 nm upon
excitation at 290 nm. In comparison, the emission blue shifted by 52 nm for 1 and 42
nm for 2, respectively. The blue-shifts of the emission peaks are probably due to
substantial electronic coupling between the neighbor ligands through the d10 (Zn2+ or
18
Cd2+) metal ions. We also examined the luminescence properties of 1 and 2 in
common organic solvents. The emission wavelength of 415 nm for 1 in acetonitrile
is the same with that of solid state sample (Fig. S7). The emission wavelength of 2 in
methanol slightly shifts from 425 nm to 431 nm in comparison with that of solid
sample (Fig. S8). The strong emissions of 1 and 2 in the solid state or in organic
suspensions indicate their potential applications in liquid phase fluorescence
7

New Journal of Chemistry
Page 8 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
detection. Also, the diffuse reflectance spectra (DRS) obviously reveal that both 1
and 2 exhibit photoresponses in the UV region (Fig. S9 and S10). Calculations based
on the Tauc equation give the band gaps (Eg) of 2.82 eV for 1 and 3.41 eV for 2,
respectively (Fig. 3a and 3b).
1.4
2.5
a
b
1.2
1.0
0.8
0.6
0.4
0.2
0.0
2.0
1.5
1.0
0.5
0.0
E =2.82 eV
g
E =3.41 eV
g
2
3
4
5
6
2
3
4
5
6
hv(eV)
hv(eV)
Fig. 3 Kubelka−Munk-transformed diffuse reflectance spectra of 1 (a) and 2 (b).
3.3 Detection of aromatic amines
Based on the fluorescence properties of 1 and 2, fluorescence detection
experiments were carried out with the acetonitrile suspension of 1 and the methanol
suspension of 2 by gradually adding the aromatic amines. The addition of aromatic
amines, such as aniline, p-toluidine, diphenylamine and p-nitroaniline, promoted the
significant fluorescence quenching or enhancement in the fluorescence intensities of
the two MOFs. The percentage of fluorescence quenching or enhancement for
different analytes is given in Fig. 4 and Fig. 5. For the selected analytes, 1 and 2
show similar sensing behaviors. Among the given analytes, p-nitroaniline
significantly quenched the fluorescence emissions of 1 and 2. When the addition
amount of p-nitroaniline was only 0.2 µmol, the fluorescence intensity of 1 at 415
nm declined by 88.92%, accompanied by a small red-shift to 430 nm (Fig. 6a). For 2,
the fluorescence intensity at 431 nm was quenched by 51.60%, accompanied by a
small red-shift to 447 nm (Fig. 6b). In contrast, other aromatic amines enhanced the
fluorescence intensities of 1 or 2 to various extents. Of particular interest is that
compound 1 exhibits a new emission at 366 nm in addition to the original peak at
415 nm. As well, compound 2 give a new emission at 368 nm in addition to the
original peak at 431 nm. Furthermore, the emission intensities enhanced drastically
8

Page 9 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
with the addition of aromatic amines into the solution. Among them, diphenylamine
gives the most significant enhancement under the same experimental conditions. For
1, the fluorescence intensity at 366 nm increased greatly even at a very low
concentration. The emission considerably intensified by 618.42% with the addition
of only 0.2 µmol diphenylamine, along with a small red- shift of the emission
wavelength. However, the original emission peak at 415 nm was slightly enhanced
by 47.01% (Fig. 7a). Compared with 1, the fluorescence intensity of 2 at 368 nm
increased more drastically and reached above 2738% even by a very low dosing of
only 0.03 µmol diphenylamine in the solution. Similarly, the original emission peak
of 2 at 431 nm increased only by 147.8% (Fig. 7b). For p-toluidine and aniline, 1 and
2 also exhibit similar performances with diphenylamine except for lower
enhancement degrees (Fig. S11 − S14). For 1, the order of enhancing efficiency for
the selected analytes is diphenylamine > aniline > p-toluidine. For 2, however, the
sequence is diphenylamine > p-toluidine > aniline.
In order to better assess the selectivity for sensing aromatic amines, triethylamine
was selected as the probe to investigate the influence of aliphatic amine on the
fluorescence of 1 and 2. As shown in Fig. S15 and S16, no obvious change occurred
in the emission intensities of the two MOFs by adding triethylamine into the
acetonitrile suspension of 1 or methanol suspensions of 2. These results demonstrate
that 1 and 2 are both selectively sensitive to aromatic amines. And also, the
sensitivity is prior to the literature reported complex: [Tb(1,3,5-btc)(H2O)6]n.(btc =
26
benzene-1,3,5-tricarboxylate).
Such selective fluorescence variation behaviors
make them potential for highly selective detection of aromatic amines.
For the two MOFs, the selective luminescence sensing of aromatic amines may be
attributed to the photoinduced electron transfer between the MOFs and the analytes
adsorbed on the surfaces of the MOFs. Generally, the electron transfer from the
electron-donating MOFs to the highly electron-withdrawing analytes will result in
43, 44
the detectable luminescence quenching effect.
The fact that p-nitroaniline
exhibits the significant quenching effect may be attributed to the excited state
electrons transfered from the frameworks of the two MOFs to analyte molecules. In
9

New Journal of Chemistry
Page 10 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
contrast, if the excited electrons transfer from the analytes to MOFs, a fluorescence
enhancement effect occurs. Thus, for other aromatic amines, the observed
enhancement in emission intensities and red-shifts in the emission wavelengths
demonstrate that the electrons possibly transfer from the given analytes to the MOFs
along with the formation of strong exciplex between them. Comparing to these
electron-rich aromatic amines, diphenylamine, which has two benzene rings, can
form stronger interactions with the MOFs. Thus, the strong interactions between
them lead to the more effective electrons transer between them. For aliphatic amines,
no obvious enhancement or quenching effects occurring may be due to the weak
interactions between the aliphatic amines and 1 or 2. And also the reduction
potentials of the two MOFs were close to that of triethylamine, lacking the driving
45
force for any photoinduced electron transfer. Hence, the luminescence properties
of the MOFs materials were unaffected by triethylamine. All the experimental results
imply that the selectivities of the MOFs are related to the structures and electronic
properties of both the MOFs and the analytes as well as the nature of their
interactions.
Fig. 4 Percentage of fluorescence quenching or enhancing of 1 obtained for different analytes in
acetonitrile at room temperature.
10

Page 11 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
Fig. 5 Percentage of fluorescence quenching or enhancing of 2 obtained for different analytes in
methanol at room temperature.
Fig. 6 Fluorescence titration of 1 (a) dispersed in acetonitrile and 2 (b) dispersed in methanol
with the addition of different volume of 10-3 M acetonitrile or methanol solution of p-nitroaniline.
The excitation wavelengths were both 310 nm and fluorescence emissions were monitored from
320 nm to 600 nm. The slit widths for both excitation and emission were 5 nm.
Fig.7 Fluorescence titration of 1 (a) dispersed in acetonitrile and 2 (b) dispersed in methanol with
the addition of different volume of 10-3 M acetonitrile or methanol solution of diphenylamine.
The excitation wavelengths were both 310 nm and fluorescence emissions were monitored from
320 nm to 600 nm. The slit widths for both excitation and emission were 5 nm.
11

New Journal of Chemistry
Page 12 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
3.4 Photocatalytic property study
Inspired by the photoresponses in the UV region of 1 and 2, we have investigated
the photocatalytic performances of 1 and 2 for the photodegradation of RhB under
UV irradiation. As shown in Fig. S17 and S18, the absorption peaks of RhB have
obviously decreased along with the prolonging of reaction time. The photocatalytic
activities increase from 4.92% (without any catalyst) to 63.10% for 1, 50.97% for 2
after 6 h under UV light irradiation. Their corresponding kinetics plots are shown in
Fig. 8.
Fig. 8 The first-order plots for photodegradation of RhB of 1 and 2
In addition, controlled experiments on the photodegradation of RhB have been
carried out. Notably, no significant change in the degradation of RhB was observed
in the following reaction conditions: (1) in the dark; (2) without catalyst; (3) under
natural light (Fig. S19 − S23). These results demonstrate that the presence of both
illumination and MOFs is necessary for the efficient degradation of RhB. Fig. 9 and
Fig. 10 present the photocatalytic degradation profiles of RhB at different conditions,
respectively. The increased degradation efficiencies compared with the controlled
experiments indicate that both 1 and 2 are active for the decomposition of RhB in the
presence of UV light irradiation. Moreover, the photocatalytic efficiency of 1 is
higher than that of 2. The difference in catalytic activity between them may be
arising from the discrepancy in central metal ions of the two MOFs.
12

Page 13 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
Fig. 9 The curves of degradation rate for RhB by 1 under different conditions
Fig. 10 The curves of degradation rate for RhB by 2 under different conditions
For the photocatalytic degradation reaction, the activity of the recycled catalyst is
a very important factor for determining the performance of the photocatalyst. Herein,
the photocatalytic reactions were re-examined five times under the irradiation of UV
light. The results show that the recovered catalysts are nearly identical to the
as-synthesized compounds. In addition, the photostabilities of the catalysts were
monitored by using PXRD patterns and IR spectra during photocatalytic reactions.
The PXRD patterns and IR spectra of MOFs had no notable differences before and
after the photocatalytic cycles under UV light irradiation (Fig. S24 - S26). Also, the
recycled MOFs exhibit similar photocatalytic performances with original MOFs (Fig.
11 and Fig. 12). The results illustrate that 1 and 2 maintain their structural integrity
after photocatalytic reactions. So, 1 and 2 may be good candidates for photocatalytic
degradation of RhB.
13

New Journal of Chemistry
Page 14 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
Fig. 11 Cycling runs of the photocatalytic degradation of RhB by 1 under UV light irradiation.
Fig. 12 Cycling runs of the photocatalytic degradation of RhB by 2 under UV light irradiation.
4. Conclusions
In summary, two luminescent transitional metal MOFs, [ZnL·H2O]n (1) and
[CdL·H2O]n·2nH2O (2) (L = 5-aminoisophthalic acid), were selected as candidates
for selective sensing aromatic amines and degrading organic dyes. The fluorescence
sensing experiments revealed that the two d10-MOFs are highly sensitive towards
aromatic amines but insensitive to aliphatic amine. For the selected aromatic amines,
p-nitroaniline acts as an electron-deficient compound and greatly quenched the
fluorescence intensities of the two MOFs. On the contrary, the other aromatic amines
significantly enhanced the fluorescence intensities of the two MOFs. Moreover, the
enhancing effect of diphenylamine is much larger than those of the others even at
very low concentration, which is in accordance with the expectation based on the
electron-rich of the analytes. These results confirm that the luminescent MOFs are
promising fluorescence sensor materials for selectively detecting aromatic amines.
Meanwhile, the excellent photocatalytic performances of both chemical stability and
14

Page 15 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
readily regeneration make the MOFs good candidates for both heterogeneous
photocatalyst and pollutants detectable materials.
Acknowledgements
This project is supported by NSFC (Grant no. 21271138), the NSF of Tianjin
(No.14JCYBJC17500), the State Key Laboratory of Inorganic Synthesis and
Preparative Chemistry of Jilin University (No. 2015-02) and The 2013 National
College Students' innovation and entrepreneurship training program
(201310058016).
Supplementary data
X-ray crystallographic file in CIF format (CCDC 1033338 for 1 and 1046705 for 2).
Crystal data (Table S1) and selected bond lengths and bond angles (Table S2). The
hydrogen bonds data (Table S3). The TG curves and the PXRD patterns of 1 and 2
(Fig. S1−S4). The fluorescence spectra of 1 and 2 at the solid state and in different
organic solvents (Fig. S5−S8). UV−vis diffuse-reflectance spectra of 1 and 2 (Fig. S9,
S10). Fluorescence titration of 1 and 2 dispersed in acetonitrile or methanol with the
addition of different analytes (Fig. S11−S16). UV/Vis absorption spectra of RhB
solution degraded by 1 and 2 under different conditions (Fig. S17−S23). The PXRD
patterns of 1 or 2 and recycled 1 or 2 (Fig. S24, S25). IR spectra of 1 or 2 before and
after photocatalytic reactions. (Fig. S26).
References
[1] H. M. Pinheiro, E. Touraud, O. Thomas, Dyes Pigments 2004, 61, 121–139.
[2] T. S. Scott, Elsevier, Amsterdam, 1962.
[3] L. M. Games, R. A. Hites, Anal. Chem. 1977, 49, 1433–1440.
[4] J. L. Wang, G. D. Wang, G. A. S. Ansari, M. F. Khan, Toxicol. Appl.
Pharmacol 2008, 230, 227–234.
[5] J. Schubert, O. Kappenstein, A. Luch, T. G. Schulz, J. Chromatogr. A 2011,
1218, 5628–5637.
[6] X. J. Huang, N. N. Qiu, D. X. Yuan, Q. M. Lin, J. Chromatogr. A 2009, 1216
15

New Journal of Chemistry
Page 16 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
4354–4360.
[7] J. S. Chiang, S. D. Huang, Talanta, 2008, 75, 70–75.
[8] X. J. Huang, T.Y. You, T. Li, X. R. Yang, E. K. Wang, Electroanalysis 1999,
11, 969–972.
[9] A. Asthana, D. Bose, A. Durgbanshi, S. K. Sanghi, W. T. Kok, J. Chromatogr.
A 2000, 895, 197–203.
[10]N. Dossi, R. Toniolo, A. Pizzariello, S. Susmel, G. Bontempelli,
Electrophoresis 2011, 32, 906–912.
[11]X. E. Zhao, Y. R. Suo, J. Sep. Sci. 2008, 31, 646–658.
[12]J. García-Lavandeira, C. Salgado-Petinal, E. Blanco, R. Cela, Anal. Bioanal.
Chem. 2010, 397, 751–763.
[13]P. Sutthivaiyakit, S. Achatz, J. Lintelmann, T. Aungpradit, R. Chanwirat, S.
Chumanee, A. Kettrup, Anal. Bioanal. Chem. 2005, 381, 268–276.
[14]R. N. Li, L. L. Wang, X. T. Gao, G. F Dua, H. L. Zhai, X. Y Wang, G. S. Guo,
Q. S. Pu, Journal of Hazardous Materials 2013, 248-249, 268−275.
[15]H. K. Chae, D. Y. Siberio-Perez, J. Kim, Y. Go, M. Eddaoudi, A. J. Matzger,
M. O’Keeffe, O. M. Yaghi, Nature 2004, 427, 523–527.
[16]H. Furukawa, N. Ko, Y. B. Go, N. Aratani, S. B. Choi, E. Y. Choi, A. O.
Yazaydin, R. Q. O’Snurr, M. Keeffe, J. Kim, O. M. Yaghi, Science 2010, 329
424–428.
[17]N. L. Rosi, J. Eckert, M. Eddaoudi, D. T. Vodak, J. Kim, M. O’Keeffe, O. M.
Yaghi, Science 2003, 300, 1127–1129.
[18]B. Gole, A. K. Bar, P. S. Mukherjee, Chem. Eur. J. 2014, 20, 2276–2291.
[19]S. Pramanik, C. Zheng, X. Zhang, T. J. Emge, J. Li, J. Am. Chem. Soc. 2011,
133, 4153–4155.
[20]M. Myersa, A. Podolska, C. Heath, M. V. Baker, B. Pejcic, Analytica Chimica
Acta. 2014, 819, 78−81.
[21]S. B. Ding, W. Wang, L. G. Qiu, Y. P. Yuan, F. M. Peng, X. Jiang, A. J. Xie, Y.
H. Shen, J. F. Zhu, Materials Letters 2011, 65, 1385−1387.
[22]S. Achmann, G. Hagen, J. Kita, I. M. Malkowsky, C. Kiener, R. Moos, Sensors
16

Page 17 of 18
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ02356K
2009, 9, 1574−1589.
[23]Z. J. Zhang, S. C. Xiang, X. T. Rao, Q. A. Zheng, F. R. Fronczek, G. D. Qian,
B. L. Chen, Chem. Comm. 2010, 46, 7205−7207.
[24]S. S. Nagarkar, B. Joarder, A. K. Chaudhari, S. Mukherjee, S. K. Ghosh,
Angew. Chem. 2013, 125, 2953−2957.
[25]J. S. Qin, S. J. Bao, P. Li, W. Xie, D. Y. Du, L. Zhao, Y. Q. Lan, Z. M. Su,
Chem. Asian J. 2014, 9, 749−753.
[26]S. M. Hu, H. L. Niu, L. G. Qiu, Y. P. Yuan, X. Jiang, A. J. Xie, Y. H. Shen, J. F.
Zhu, Inorg. Chem. Comm. 2012, 17, 147−150.
[27]L. Q. Shi, C. He, D. F. Zhu, Q. G. He, Y. Li, Y. Chen, Y. X. Sun, Y. Y. Fu, D.
Wen, H. M. Cao, J. G. Cheng, J. Mater. Chem. 2012, 22, 11629−11635.
[28]P. Falcaro, F. Normandin, M. Takahashi, P. Scopece, H. Amenitsch, S.
Costacurta, C. M. Doherty, J. S. Laird, M. D. H. Lay, F. Lisi, A. J. Hill, D.
Buso, Adv. Mater. 2011, 23, 3901–3906.
[29]D. X. Ma, B. Y. Li, X. Zhou, Q. Zhou, K. Liu, G. Zeng, G. H. Li, Z. Shi, S. H.
Feng, Chem. Commun., 2013, 49, 8964–8966.
[30]L. L. Wen, L. Zhou, B. G. Zhang, X. G. Meng, H. Qua, D. F. Li, J. Mater.
Chem. 2012, 22, 22603−22609.
[31]W. Q. Kan, B. Liu, J. Yang, Y. Y. Liu, J. F. Ma, Cryst. Growth & Des. 2012, 12,
2288−2298.
[32]C. Q. Xu, H. H. Wu, F. L. Gu, Journal of Hazardous Materials 2014, 275,
185−192.
[33]R. Li, X. Q. Ren, H. W. Ma, X. Feng, Z. G. Lin, X. G. Li, C. W. Hu, B. Wang,
J. Mater. Chem. A. 2014, 2, 5724−5729.
[34]S. Q. Zhang, L. Han, L. N. Li, J. Cheng, D. Q. Yuan, J. H. Luo, Cryst. Growth
& Des. 2013, 13, 5466−5472.
[35]C. D. Wu, C. Z. Lu, W. B. Yang, H. H. Zhuang, J. S. Huang, Inorg. Chem.
2002, 41, 3302–3307.
[36]W. B Yuan, T. Liu, Z. G. Guo, H. F. Li, R. Cao, J. Mol. Struc. 2010, 965,
82–88.
17

New Journal of Chemistry
Page 18 of 18
View Article Online
DOI: 10.1039/C4NJ02356K
[37]Q. X. Liao, Y. G. Yao, Chin. J. Struct. Chem. 2006, 4, 465-468.
[38]K. L. Zhang, N. Qiao, H. Y. Gao, F. Zhou, M. Zhang, Polyhedron 2007, 26,
2461-2469.
[39]J. Tao, X. Yin, Y. B. Jiang, R. B. Huang, L. S. Zheng, Inorg. Chem. Commun.
2003, 6, 1171-1174.
[40]G. M. Sheldrick, SHELXS-97, Program for Crystal Structure Solution,
University of Göttingen, Germany 1997.
[41]G. M. Sheldrick, SHELXL–97, Program for Crystal Structure Refinement,
University of Göttingen, Germany 1997.
[42]G. M. Sheldrick, SADABS, Program for Empirical Absorption Correction of
the Area detector Data, University of Göttingen, Germany 1996.
[43]S. Pramanik, Z. C. Hu, X. Zhang, C. Zheng, S. Kelly, J. Li, Chem. Eur. J. 2013,
19, 15964−15971.
[44]J. M. Zhou, W. Shi, H. M. Li, H. Li, P. Cheng, J. Phys. Chem. C. 2014, 118,
416−426.
[45]S. W. Thomas III, J. P. Amara, R. E. Bjork, T. M. Swager, Chem. Commun.
2005, 17, 4572−4574.
18