Current Organic Chemistry - Volume 22, Issue 18, 2018

This short review is aimed at summarizing the most recent developments in using MOFs as the catalysts in heterogeneous catalysis, such as addition and condensation reactions, coupling reactions, cycloaddition reactions, multicomponent reactions, oxidation reactions, reduction of carbon dioxide, enantioselective reactions, hydrogen evolution reactions, polymerization reactions, selective reduction of NOx, and degradation of pollutants.

Metal-organic frameworks have been largely investigated as gas adsorbent materials in the past two decades. With deep investigation of crystallography, the rational adjustments of SBUs, linker geometry, linker length, functional groups and guest molecules, the size, shape, and internal surface property of MOFs can be tuned. One of the hottest topics for the application of this type of high porous material is the gas storage and separation, especially for hydrogen and methane, which are two gases with high specific energy. In this critical review, we highlight the design strategies of MOFs through three aspects: the SBUs, linkers and post-synthesis. Then we review the recent progress of MOFs in the storage and separation of hydrogen and methane. Examples of the functional designed MOFs for storage or separation of hydrogen and methane are described respectively.

Due to the environmental and energy issues in the world, the chemical fixation of carbon dioxide into valuable products has been attracted many attentions in the recent years. However, the utilization of the highly chemical stabile carbon dioxide requires high bond cleavage energy of C=O bond. Thus, seeking and developments of the suitable catalysts for the chemical fixation of carbon dioxide is quite important. Metal-organic frameworks (MOFs), as a kind of porous materials, exhibit intriguing structural diversity and outstanding physical and chemical properties. Their modular nature and facile tunability make these materials ideal heterogeneous catalysts because they possess active sites and accessible channels for the attraction and retention of substrates. In this review, we intended to discuss the recent advances on some of the most interesting chemical fixation catalysis starting from CO2 based on MOFs materials as heterogeneous catalysts under different conditions. Among all these excellent works, we hope to find and highlight the effective approaches and technique in this field, and analyze the opportunities and limitations for the MOFs catalysts for the future applications.

Photocatalysis can transform solar energy into chemical energy and is a promising technology to ameliorate the current environmental pollution and energy shortage. Due to their unique structural characteristics, metal-organic frameworks (MOFs), a class of micro-mesoporous hybrid materials, are recently emerging as a new type of photocatalysts and have already been applied for a variety of photocatalytic reactions, including the most relevant for environmental concerns such as CO2 reduction, H2 evolution, the oxidation of various pollutants as well as light-induced organic transformations. Although a number of excellent reviews on MOF-based photocatalysis have already been published, the current short review focuses on different strategies to engineer the MOF-based photocatalysts, with an aim for efficient photocatalysis. The review summarized different strategies to enhance the light absorption of the MOFs and improve the photogenerated charge separation, which is considered to be important factors in influencing the performance of the photocatalysts. As a unique advantage of using MOFs as photocatalysts, the implementing of other catalytic active sites into a single MOF material to enable the MOFs to behave as a multifunctional catalyst for light-induced tandem/cascade reactions was also introduced in this review. Finally, personal opinions on the opportunities and challenges facing the MOFs-based photocatalysis and its developing trend were also addressed. We hope that this review can provide some guidance for a rational development of highly efficient MOFs-based photocatalysts and serve as a starting point to design more MOF-based multifunctional catalysts via a successful coupling of MOF-based photocatalysis with molecular catalysis/metal catalysis/organocatalysis since we believed that it is the trend of the MOF-based photocatalysis.

This review depicts in a concise way the oxidation reactions (C-H, double bond and oxidative cleavage) in natural products. The introduction of oxygen atom in natural products is an improved strategy to achieve pharmacologically active molecules or their synthetic analogues. Natural products are considered most intriguing skeletons to be synthesized in the laboratory mainly because they are blessed with multifunctional groups in one entity. The presence of more than one functional group in the molecules provokes the daunting tasks such as functional group tolerance and regio- or chemo-selectivity. Oxidation reaction is one of the widely exercised reactions in natural products chemistry as it renders the formation of new derivatives or analogues just by insertion of oxygen atom. Over the past decades, several oxidants have been reported but among all, the oxidant dimethyldioxirane (DMDO) holds great promise as it is attributed with mild reactivity, high functional group tolerance, excellent chemo- and regio-selectivity, ecofriendly and is easy to use and prepare, so these fascinating features provide immense incentive to natural product chemist to insert oxygen atom with great ease in natural products.

Liverworts, widely used as traditional Chinese medicine, are a rich source of structurally diverse secondary metabolites with intriguing biological activities. Given that diterpenoids present in liverwort species possess striking scaffoldings and considering the absence of any previous review on this subject, we present an updated analysis of the diterpenes in liverworts along with their biological activities based on literature dated from 1997 to present. This comprehensive effort is expected to lay the foundation for further research on the diterpenes in liverworts.