Metal Organic Frameworks: A New Generation Coordination Polymers for Visible Light Photocatalysis

Fabrication of Fe-BTC on aramid fabrics for repeated degradation of isoproturon

Catalytic degradation is a promising and ideal technology in environmental remediation. Among them, catalytic oxidation and photocatalysis respectively based on catalysts and photocatalysts both trigger broad interests because of their high removal activity. However, the reusability of the powder catalysts still faces substantial challenges. Here, a simple strategy is proposed to load Fe-BTC catalyst on aramid fabrics (AF) to construct Fe-BTC MOF @ aramid fabric (Fe-BTC@AF) composite materials with layer-by-layer in situ self-assembly methods. The experimental results illustrated that 98% isoproturon could be removed by Fe-BTC@AF₂₀ with oxidant H₂O₂, while the single Fe-BTC@AF₂₀ could photo-degrade 99% isoproturon within 7 h. Meanwhile, it could sustain a high degradation rate of more than 80%, even if it had gone through 5 degradation cycles. Thus, the Fe-BTC@AF composite has a significant advantage in the recycling ability for degradation of isoproturon, which will have potential applications in the efficient removal of organic contaminants in water.

Effect of sulfur doping of zinc-imidazole coordination polymer (ZnIm CP) as a novel photocatalyst for degradation of ionic dyes

Zinc-Imidazole coordination polymer (ZnImCP) was simply synthesized hydrothermally at relatively low temperature (70 °C) from zinc acetate and imidazole. ZnImCP was treated by sulfide solution to produce sulfur-doped samples (S-ZnImCPs). Structures of the synthesized ZnImCP and S-ZnImCPs were characterized through FTIR, PXRD, and, Raman, SEM/EDX, N2-BET, UV–VIS DRS, and pHpzc analyses. The photocatalytic performances of pristine CP and sulfur modified CPs under visible and ultra-violet irradiations for degrading the cationic methylene blue (MB) and the anionic methyl orange (MO) were investigated considering different initial pH values 4, 7 and 10. Under visible light, the results indicate that these CPs display considerable photocatalytic degradation towards the cationic MB for the initial pH 4 and 7 where degradation increases with sulfur content. While under ultra-violet, results indicate considerable photocatalytic degradation towards both dyes for the initial pH 7 and 10 where degradation increases with sulfur content which indicates the gainful of non-metal dopping. The buffering nature of CPs and the type of radiation considering determined band-gap values effectively influence the degradation mechanisms.

Photocatalytic CO2 Conversion Using Metal-Containing Coordination Polymers and Networks: Recent Developments in Material Design and Mechanistic Details

International guidelines have progressively addressed global warming which is caused by the greenhouse effect. The greenhouse effect originates from the atmosphere’s gases which trap sunlight which, as a consequence, causes an increase in global surface temperature. Carbon dioxide is one of these greenhouse gases and is mainly produced by anthropogenic emissions. The urgency of removing atmospheric carbon dioxide from the atmosphere to reduce the greenhouse effect has initiated the development of methods to covert carbon dioxide into valuable products. One approach that was developed is the photocatalytic transformation of CO2. Photocatalysis addresses environmental issues by transferring CO2 into value added chemicals by mimicking the natural photosynthesis process. During this process, the photocatalytic system is excited by light energy. CO2 is adsorbed at the catalytic metal centers where it is subsequently reduced. To overcome several obstacles for achieving an efficient photocatalytic reduction process, the use of metal-containing polymers as photocatalysts for carbon dioxide reduction is highlighted in this review. The attention of this manuscript is directed towards recent advances in material design and mechanistic details of the process using different polymeric materials and photocatalysts.

Direct growth of two-dimensional phthalocyanine-based COF on Cu-MOF to construct a photoelectrochemical-electrochemical dual-mode biosensing platform for high-efficiency determination of Cr(III)

A photoelectrochemical (PEC)-electrochemical (EC) dual-mode biosensing strategy based on COF@MOF heterostructure was developed for efficiently analyzing Cr(III) ions. A two-dimensional phthalocyanine-based COF (CoPc-PT-COF) was in situ grown on a Cu-based MOF (Cu-MOF) substrate via covalent binding between carboxyl groups in Cu-MOF and amino groups in CoPc-PT-COF (denoted as CoPc-PT-COF@Cu-MOF). The coexistence of both phthalocyanine and bipyridine in CoPc-PT-COF@Cu-MOF affords the outperformed electro- and photo-activities, thus serving as a photoelectric beacon with favorable energy-band configuration and amplified electrochemical response. Due to the high porosity and rich functionality of the obtained heterostructure, the DNA strands can be tightly anchored over CoPc-PT-COF@Cu-MOF via diverse interactions. Thanks to the specific recognition between DNA strands and Cr³⁺ ions, the CoPc-PT-COF@Cu-MOF-based biosensor can be used to determine Cr³⁺ ions in an aqueous environment by PEC-EC mode. The gained biosensor shows an extremely low limit of detection (LOD) of 14.5 fM (for PEC) and 22.9 fM (for EC) within the Cr³⁺ concentration range from 0.1 pM to 100 nM, along with high selectivity, good reproducibility and stability. Moreover, this novel biosensor exhibits acceptable applicability for analyzing the trace Cr³⁺ from diverse samples (e.g., river and tap water). As a result, this work provides new insights into the construction of a high-efficiency PEC-EC dual-mode biosensor for detecting heavy metal ions from complex environments.

An Ion-Exchangeable MOF with Reversible Dehydration and Dynamic Structural Behavior (NH4 )2 [Zn2 (O3 PCH2 CH2 COO)2 ]⋅5 H2 O (BIRM-1)

(NH₄ )₂ [Zn₂ (O₃ PCH₂ CH₂ COO)₂ ]⋅5 H₂ O (BIRM-1) is a new metal phosphonate material, synthesized through a simple hydrothermal reaction between zinc nitrate and 3-phosphonopropionic acid, using urea and tetraethylammonium bromide as the reaction medium. In common with other metal-organic framework materials, BIRM-1 has a large three-dimensional porous structure providing potential access to a high internal surface area. Unlike most others, it has the advantage of containing ammonium cations within the pores and has the ability to undergo cation exchange. Additionally, BIRM-1 also exhibits a reversible dehydration behavior involving an amorphization-recrystallization cycle. The ability to undergo ion exchange and dynamic structural behavior are of interest in their own right, but also increase the range of potential applications for this material. Here the crystal structure of this new metal phosphonate and its ion exchange behavior with K⁺ as an exemplar are studied in detail, and its unusual structure-reviving property reported.

Charge, adsorption, water stability and bandgap tuning of an anionic Cd(ii) porphyrinic metal–organic framework

By changing the occupancies of the metal ions and counterions, the tuning of the framework charge, band-edge position and bandgap of a novel Cd(ii) porphyrinic MOF 1 was achieved.

Assembly of ZnII-coordination polymers constructed from benzothiadiazole functionalized bipyridines and V-shaped dicarboxylic acids: topology variety, photochemical and visible-light-driven photocatalytic properties

Photocatalytic properties of four benzothiadiazole functionalized coordination polymers have been reported.