Latest ArticlesTo address the pressing global need for carbon-neutral fuels, optimizing the conversion of biomass to bio-oil (bio-chemicals) is crucial. Here, we introduce MXene (Ti3C2Tx) as an innovative catalyst in biomass pyrolysis, exhibiting significant prowess in boosting levoglucosan yields. Py-GC/MS analysis indicated a remarkable 438% enhancement in levoglucosan yield when a 5 wt% catalyst-to-biomass ratio was employed. Laboratory-scale studies achieved an impressive 13.95 wt% levoglucosan in ex-situ fixed-bed catalytic pyrolysis, a yield that is 19.6 times higher than that from pure biomass at 40 wt% catalyst loading. Recycling evaluations affirm the robust stability of the MXene catalyst, validating its potential for multiple use cycles in eco-friendly industrial levoglucosan production.
Near infrared-II (NIR-II) dyes have unique advantages in biomedical applications owing to the powerful ability in penetrating biological tissues. Herein, NIR-II aza-BODIPY dye, QLD-BDP, was developed with julolidine at 1,7-sites and p-dimethylaminophenyl group at 3,5-sites. According to X-ray analysis, QLD-BDP exhibits significant distortion, and this molecule appears a bowl shaped structure. The photothermal conversion efficiency of the self-assembled QLD-BDP nanoparticles (QLD-BDP-NPs) can reach 50.5%, with maximum emission at 998 nm by the aggregate. QLD-BDP-NPs can cause the complete destruction of 4T1 multicellular spheroids (MCSs), indicating a photothermal therapy (PTT) effect.
To efficiently remove perfluorooctanoic acid (PFOA), we developed a composite of magnetic Fe3O4 nanocrystals and MIL-101 (an iron-based metal organic framework). Because of its high surface area, porous structure, and complexation between PFOA as confirmed by experimental results and density functional theory simulation, the magnetic composite showed a Langmuir adsorption capacity of 415 mg/g in the presence of various groundwater components, and thus adsorbed PFOA at environment-relevant concentration within 20 min. The catalyst loaded with PFOA can then be magnetically separated from the synthetic groundwater. This adsorption step concentrated PFOA near MIL-101 and resulted in a fast decomposition rate in the decomposition step, where MIL-101 served as an efficient Fenton agent due to its abundant Fe3+/Fe2+ sites. Meanwhile, the alternative magnetic field was introduced to change the production pathway of reactive oxygen species and superoxide radical anions were produced, which was critical for PFOA degradation. In addition, the inductive heating effect heat the magnetic particles to 445 K through an in-situ approach, which thus further accelerated Fenton reactions rate. In addition, and achieved a complete degradation of PFOA within 30 min. This newly developed Fenton catalyst demonstrates advantages over conventionally heterogeneous and homogeneous catalysts, and thus is promising for practical applications.
The highly desired goal is to employ visible light for the photocatalytic reduction of toxic Cr(VI) to environmentally friendly Cr(III). Metal-organic frameworks (MOFs) are considered one of the most promising materials for the photoreduction of Cr(VI). Nevertheless, developing MOFs with high stability and activity is still challenging. Herein, we report a stable Zn-based MOF (named DZU-64) with an anthracene functionalized ligand, and its reduction of Cr(VI) under sunlight irradiation was investigated. DZU-64 exhibits excellent chemical stability in pH range of 2−14 aqueous solution, and remarkable thermal stability to 570 ℃. For the photoreduction of Cr(VI) under visible light irradiation, DZU-64 gives a record rate constant of 0.467 min−1 and a high Cr(VI) reduction rate of 6.68 mg Cr(VI) gcata−1 min−1 at pH 2. Moreover, under real solar light, DZU-64 can also efficiently reduce Cr(VI) to Cr(III) while retaining its catalytic activity throughout 5 cycles without any notable decline, further demonstrating its great application prospect. By combining the photovoltaic performance tests and electron spin resonance test, the possible photoreduction of Cr(VI) mechanism in DZU-64 was analyzed.
Zeolites are crystalline porous materials that are used in the chemical industry for adsorption, separation and catalytic reactions. Chiral zeolites have shown promise in enantioselective adsorption and catalytic organic reactions, attracting significant research interest. Recent advances have been made in the rational design, computational prediction and hydrothermal synthesis of using chiral organic structure-directing agents. Additionally, newly developed electron microscopic techniques have been utilized to analyze the structure and determine absolute configuration. The following review aims to provide an overview of the development history of chiral zeolites, examine several prominent chiral zeolite structures discovered so far, discuss the recent progress in characterization methods and explore their potential applications.
Efficient yield of 1O2 determines the photocatalytic degradation rate of antibiotics, but the regulatory mechanism for 1O2 selective generation in O2 activation is still lacking exploration. Herein, oxygen vacancy (OV) modification strategy of MIL-125 was successfully practiced to promote the selective generation of 1O2. Multiple characterizations including extended X-ray absorption fine structure (EXAFS) and electron paramagnetic resonance spectra (EPR) confirmed the formation of oxygen vacancy in OV-MIL-125. The synthesized OV-MIL-125 exhibited greatly enhanced 1O2 selective (~90%) and antibiotics removal rate in water with high mineralization rate. Dynamics analysis of excitons by transient-steady state fluorescence and phosphorescence, transient absorption spectra (TAS) revealed that oxygen vacancy greatly enhanced the intersystem crossing (ISC) of singlet exciton, promoting triplet exciton generation. Density functional theoretical (DFT) calculation also proved the reduced gap of intersystem (ΔEST) and the modulated highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) population which was conducive to intersystem crossing process. Calculation of transition state further confirmed the lower energy barrier for π* orbital spin flip of O2 adsorbed on OV-MIL-125. The Dexter energy transfer involving triplet annihilation dominated the O2 activation mechanism to generate 1O2 instead of the charge transfer to generate O2•− which happened in MIL-125. This study provides new thinking for photocatalytic activation of molecular oxygen and is expected to guide the design of MOF-based catalysts for water treatment.
Antibiotics present in surface water have detrimental effects on both human health and the ecosystem. Additionally, they pose a threat to the effectiveness of biological water treatment processes. In this study, a visible photocatalytic system with BiOCl/g-C3N4 heterojunction was developed to remove sulfonamide antibiotic sulfamerazine (SMZ) in water. The removal rate reached 92.77% under visible light irradiation for 80 min. This photocatalyst remained active after 5 cycles of experiments and maintained a relatively stable removal rate of SMZ of over 80%. The ESR tests indicate that the main active species in this photocatalytic system were h+ and •O2−. The enhanced photocatalytic efficiency was mainly ascribed to the formation of a built-in electric field between BiOCl and g-C3N4 through the carrier transport mechanism of the S-scheme heterojunction. This heterojunction facilitated the photogenerated carrier shift and segregation, and improved the interfacial charge transfer efficiency, as confirmed by photoelectrochemical test and Density functional theory (DFT) calculations. The HPLC-QTOF-MS/MS and DFT analysis revealed possible degradation pathways of SMZ may involve deamination, hydroxylation, SO2 extrusion and bond breaking. This novel BiOCl/g-C3N4 heterojunction has proven to be essential for efficient visible-light photocatalysis.
Host-guest recognition-based macrocycle in macrocycle to form "Russian doll" assemblies remains an interesting topic in supramolecular chemistry. Herein, a macrocycle-in-macrocycle assembly was studied using cucurbit[10]uril (Q[10]) and the smallest cucurbituril-like macrocycle (TD[4]). X-ray crystal structure analysis revealed that TD[4] was encapsulated in the cavity of Q[10] to form a 1:1 complex. Importantly, competitive guest studies suggested that TD[4] had the highest binding constant with the Q[10] host among the guests used, including Q[5], Me8TD[4], and amantadine molecules in water. Our results provided a new cucurbituril-based Russian-doll structure containing both the largest and smallest cavities of the cucurbiturils, which expanded the family of molecular Russian dolls.
Aromatic aldehydes are the most fundamentally important compounds used in organic synthesis. The development of new synthetic methods for introduction of a formyl group into an organic scaffold is highly desirable. In this report, a nickel-catalyzed reductive coupling between aryl halides and α–chloro N-methoxyphthalimide has been documented for the synthesis of a diverse array of aromatic aldehydes. Because of mild reductive coupling conditions, excellent functional group tolerance, especially for substrates containing free -OH and -NH2, was observed. Due to the simple operation mode, a large library of aromatic aldehydes can be quickly constructed by this process. Moreover, the present protocol is amenable for late-stage functionalization of bioactive compound. A combined computational and experimental investigation suggested the reaction may undergo a reaction mechanism of active Ni(I) catalyst formation and the formation of key formyl radical intermediate under zinc reductive conditions.
The homochiral compounds play an important role in human health and pharmaceutical industry. Currently, the chromatographic enantioseparation has become one of the most effective and practical approach to obtain pure enantiomers. Herein, the exploration of advanced materials, using as chromatographic chiral stationary phases for racemic separation, has attracted great attention. Thanks to their high enantioselectivity and controllable synthesis, the emerging chiral metal-organic frameworks (CMOFs) have been widely studied as the stationary phase in chromatographic technology. In this review, we will summarize the principles of synthetic strategies and mechanism of chiral microenvironment. In particular, the recent progress and research hotspot of CMOFs regarding as the chiral stationary phases in gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrochromatography (CEC), are elucidated systematically according to the published work. Last but not the least, we also highlight the challenges and perspectives of rational design of CMOFs, as well as their corresponding racemic separation. We envision that the review will provide a further understanding of CMOFs and facilitate the development of chromatographic enantioselective applications.
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