While limited choice of emissive organic linkers with systematic emission tunability presents a great challenge to investigate energy transfer (ET) over the whole visible light range with designable ...directions, luminescent metal‐organic frameworks (LMOFs) may serve as an ideal platform for such study due to their tunable structure and composition. Herein, five Zr6 cluster‐based LMOFs, HIAM‐400X (X=0, 1, 2, 3, 4) are prepared using 2,1,3‐benzothiadiazole and its derivative‐based tetratopic carboxylic acids as organic linkers. The accessible unsaturated metal sites confer HIAM‐400X as a pristine scaffold for linker installation. Six full‐color emissive 2,1,3‐benzothiadiazole and its derivative‐based dicarboxylic acids (L) were successfully installed into HIAM‐400X matrix to form HIAM‐400X‐L, in which the ET can be facilely tuned by controlling its direction, either from the inserted linkers to pristine MOFs or from the pristine MOFs to inserted linkers, and over the whole range of visible light. The combination of the pristine MOFs and the second linkers via linker installation creates a powerful two‐dimensional space in tuning the emission via ET in LMOFs.
Tunable energy transfer with designable direction, from second linkers to pristine MOFs or from pristine MOFs to second linkers, was achieved in the whole visible spectrum via installing color‐full emissive second linkers into the full‐color emissive pristine MOFs.
The development of nanoscaled luminescent metal–organic frameworks (nano‐LMOFs) with organic linker‐based emission to explore their applications in sensing, bioimaging and photocatalysis is of great ...interest as material size and emission wavelength both have remarkable influence on their performances. However, there is lack of platforms that can systematically tune the emission and size of nano‐LMOFs with customized linker design. Herein two series of fcu‐ and csq‐type nano‐LMOFs, with precise size control in a broad range and emission colors from blue to near‐infrared, were prepared using 2,1,3‐benzothiadiazole and its derivative based ditopic‐ and tetratopic carboxylic acids as the emission sources. The modification of tetratopic carboxylic acids using OH and NH2 as the substituent groups not only induces significant emission bathochromic shift of the resultant MOFs, but also endows interesting features for their potential applications. As one example, we show that the non‐substituted and NH2‐substituted nano‐LMOFs exhibit turn‐off and turn‐on responses for highly selective and sensitive detection of tryptophan over other nineteen natural amino acids. This work sheds light on the rational construction of nano‐LMOFs with specific emission behaviours and sizes, which will undoubtedly facilitate their applications in related areas.
Nano‐luminescent metal–organic frameworks (LMOFs), with precise size control and emission colors from blue to near‐infrared, were prepared using 2,1,3‐benzothiadiazole and its derivative based ditopic‐ and tetratopic carboxylic acids as the emission sources. The nano‐LMOFs exhibit turn‐off and turn‐on responses for highly selective and sensitive detection of tryptophan over nineteen other natural amino acids.
Luminescent metal–organic frameworks (LMOFs) demonstrate strong potential for a broad range of applications due to their tunable compositions and structures. However, the methodical control of the ...LMOF emission properties remains a great challenge. Herein, we show that linker engineering is a powerful method for systematically tuning the emission behavior of UiO-68 type metal–organic frameworks (MOFs) to achieve full-color emission, using 2,1,3-benzothiadiazole and its derivative-based dicarboxylic acids as luminescent linkers. To address the fluorescence self-quenching issue caused by densely packed linkers in some of the resultant UiO-68 type MOF structures, we apply a mixed-linker strategy by introducing nonfluorescent linkers to diminish the self-quenching effect. Steady-state and time-resolved photoluminescence (PL) experiments reveal that aggregation-caused quenching can indeed be effectively reduced as a result of decreasing the concentration of emissive linkers, thereby leading to significantly enhanced quantum yield and increased lifetime.
Electrochemical redox conversion between ferricyanide and ferrocyanide on a gold electrode is one of the most classical reactions in electrochemistry. In textbooks, the gold electrode is seen as ...chemically inert, on which only the adsorption/desorption of Fe(CN)
6
3/4−
and electron transfer take place. Here, the electrochemical process of Fe(CN)
6
3/4−
on a gold electrode was revisited using a vacuum-compatible microfluidic electrochemical cell in combination with operando liquid ToF-SIMS. An intermediate, Au(CN)
2
−
, was observed in the cyclic voltammetry of ferricyanide with an interesting periodic potential-dependent variation trend. It was demonstrated that the gold electrode participated in the redox reaction of Fe(CN)
6
3/4−
by competing with it to form Au(CN)
2
−
, since the formation constant was Fe(CN)
6
3−
> Au(CN)
2
−
> Fe(CN)
6
4−
. The formation and evolution of Au(CN)
2
−
depends on the ratio of Fe(
iii
) and Fe(
ii
) on the surface of the gold electrode, which was determined by the redox conversion between Fe(
iii
) and Fe(
ii
) as well as the electric field force-based attraction or repulsion between the gold electrode and Fe(CN)
6
3/4−
. Both of these factors were potential-dependent, resulting in the periodic change of Au(CN)
2
−
in the dynamic potential scan of Fe(CN)
6
3/4−
. These results provided solid molecular evidence for the participation of the gold electrode in the Fe(CN)
6
3/4−
redox system, which will deepen mechanistic understandings of related electrochemical applications.
Our results indicated that a gold electrode participates in the redox reaction of Fe(CN)
6
3/4−
by competing with it to form Au(CN)
2
−
.
Herein, organic linker-based near-infrared-I (NIR-I) emissive metal–organic frameworks (MOFs), with a maximum emission peak at 741 nm, were synthesized via linker engineering. By integration of ...stronger acceptor and donor groups into one linker, a significant bathochromic-shift is realized. This MOF exhibits great selectivity and sensitivity for aniline and p -phenylenediamine detection. This finding provides new insights into the rational design of NIR-MOFs for sensing and related applications.
Near-infrared (NIR)-emitting materials have been extensively studied due to their important applications in biosensing and bioimaging. Luminescent metal-organic frameworks (LMOFs) are a new class of ...highly emissive materials with strong potential for utilization in biomedical related fields because of their nearly unlimited structural and compositional tunability. However, very little work has been reported on organic linker-based NIR-MOFs and their emission properties. In the present work, a series of yttrium-tetracarboxylate-based LMOFs (HIAM-390X) are prepared
via
judicious linker design to achieve NIR emission with diverse structures. The introduction of an amino group not only offers the remarkable emission bathochromic shift from 521 nm, 665 nm to 689 nm for the resultant MOFs, but also influences the linker conformations, leading to the topology evolution from (4,12)-c ftw, (4,8)-c scu, which is rarely reported in rare earth element-based MOFs, to an unprecedented topology hlx for HIAM-3901 (without an amino group), HIAM-3905 (with one amino group) and HIAM-3906 (with two amino groups). Among these MOFs, HIAM-3907 shows an emission maximum at ∼790 nm, with the emission tail close to 1000 nm. The NIR emission may be attributed to the combination of the strongly electron-donating amino group and the strongly electron-withdrawing acceptor naphtho2,3-
c
1,2,5selenadiazole. This work sheds light on the rational design of organic linker-based LMOFs with controlled structures and NIR emission, and inspires future interest in biosensing and bioimaging related applications of NIR-MOFs.
Introduction of amino groups into linkers will not only induce a significant emission red-shift to near-infrared, but also increase structural diversity of resultant LMOFs, leading to structural change from
ftw
,
scu
to an unprecedented topology
hlx
.
Luminescent metal–organic frameworks (LMOFs) have been extensively studied for their potential applications in lighting, sensing and biomedicine-related areas due to their high porosity, unlimited ...structure and composition tunability. However, methodical development in systematically tuning the emission properties of fluorescent organic linker-based LMOFs to facilitate the rational design and synthesis of target-specific materials has remained challenging. Herein we attempt to build an emission library by customized synthesis of LMOFs with targeted absorption and emission properties using donor–acceptor–donor type organic linkers. By tuning the acceptor groups ( i.e. 2,1,3-benzothiadiazole and its derivatives), donor groups (including modification of original donors and use of donors with different metal–linker connections) and bridging units between acceptor and donor groups, an emission library is developed for LMOFs with their emissions covering the entire visible light range as well as the near-infrared region. This work may offer insight into well controlled design of organic linkers for the synthesis of LMOFs with specified functionality.
Herein, three tritopic carboxylic acids were used to construct three Zr-MOFs, HIAM-4033, HIAM-4034, and HIAM-4035, to investigate the effect of carboxyl position on the MOF structures. The results ...showed that HIAM-4033 and HIAM-4034 possess (3,9)-c models with different underlying nets, whereas HIAM-4035 exhibits the same underlying net as UiO-68. Nanosized HIAM-4033 exhibits excellent sensitivity and selectivity for detecting aromatic acids, such as benzoic acid and 2-fluorobenzoic acid, compared with aliphatic acids and inorganic acids. This study offers new insights into achieving an organic linker directed structure evolution of Zr-MOFs, which might facilitate the discovery of unprecedented underlying nets.
Zr-MOFs with different topologies were constructed by changing carboxyl group positions on thiophene moiety of tritopic carboxylic acids, which provides new insights into investigating organic linker directed structure evolution of Zr-MOFs.
We demonstrate the assembly of a mononuclear metal center, a hexanuclear cluster, and a V-shaped, trapezoidal tetracarboxylate linker into a microporous metal–organic framework featuring an ...unprecedented 3-nodal (4,4,8)-c lyu topology. The compound, HIAM-302, represents the first example that incorporates both a primary building unit and a hexanuclear secondary building unit in one structure, which should be attributed to the desymmetrized geometry of the organic linker. HIAM-302 possesses optimal pore dimensions and can separate monobranched and dibranched alkanes through selective molecular sieving, which is of significant value in the petrochemical industry.
Metal–organic frameworks (MOFs) exhibit strong potential for applications in molecular adsorption and separation because of their highly tunable structures and large specific surface areas and have ...also been used for iodine capture. However, most works on MOF-based iodine capture focus on the adsorption capacity while taking little consideration of the capture rate and efficiency. Herein, we report the design of a saddle-shaped tetratopic carboxylic acid containing four thiophene groups (H4COTTBA) and the synthesis of a 4,8-connected flu-type zirconium MOF (HIAM-4014) using this linker. HIAM-4014 exhibits highly efficient iodine capture. The large cagelike pore structure, OH– groups on the unsaturated Zr6 clusters, electron-rich nature of the thiophene group in the linker, and high surface area are all attributed to the tetrahedral geometry of H4COTTBA, which endows HIAM-4014 with a relatively high iodine adsorption capacity of 2.50 g/g within 2 h and an equilibrium adsorption capacity of 2.68 g/g after 5 h. Coupled with a high elution ratio and great recyclability, HIAM-4014 is a good candidate for the efficient removal of waste iodine.
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