Metal–organic frameworks (MOFs), established as a relatively new class of crystalline porous materials with high surface area, structural diversity, and tailorability, attract extensive interest and exhibit a variety of applications, especially in catalysis. Their permanent porosity enables their inherent superiority in confining guest species, particularly small metal nanoparticles (MNPs), for improved catalytic performance and/or the expansion of reaction scope. This is a rapidly developing interdisciplinary research field. In this review, we provide an overview of significant progress in the development of MNP/MOF composites, including various preparation strategies and characterization methods as well as catalytic applications. Special emphasis is placed on synergistic effects between the two components that result in an enhanced performance in heterogeneous catalysis. Finally, the prospects of MNP/MOF composites in catalysis and remaining issues in this field have been indicated.

Metal–organic frameworks meet metal nanoparticles: synergistic effect for enhanced catalysis

Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow Until recently, however, the question, “Should we do this in flow?” has merely been an afterthought This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts

The Hitchhiker's Guide to Flow Chemistry

Helicenes: synthesis and applications.

Occurrence, Biogenesis, and Synthesis of Biologically Active Carbazole Alkaloids

Efficient transformation of biomass to value-added chemicals and high-energy density fuels is pivotal for a more sustainable economy and carbon-neutral society. In this framework, developing potential cascade chemical processes using functionalised heterogeneous catalysts is essential because of their versatile roles towards viable biomass valorisation. Advances in materials science and catalysis have provided several innovative strategies for the design of new appealing catalytic materials with well-defined structures and special characteristics. Promising catalytic materials that have paved the way for exciting scientific breakthroughs in biomass upgrading are carbon materials, metal–organic frameworks, solid phase ionic liquids, and magnetic iron oxides. These fascinating catalysts offer unique possibilities to accommodate adequate amounts of acid–base and redox functional species, hence enabling various biomass conversion reactions in a one-pot way. This review therefore aims to provide a comprehensive account of the most significant advances in the development of functionalised heterogeneous catalysts for efficient biomass upgrading. In addition, this review highlights important progress ensued in tailoring the immobilisation of desirable functional groups on particular sites of the above-listed materials, while critically discussing the role of consequent properties on cascade reactions as well as on other vital processes within the bio-refinery. Current challenges and future opportunities towards a rational design of novel functionalised heterogeneous catalysts for sustainable biomass valorisation are also emphasized.

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Functionalised heterogeneous catalysts for sustainable biomass valorisation

Asymmetric aldol reactions catalyzed by a novel polystyrene-immobilized proline derivative occur in short reaction times with excellent diastereo- and enantioselectivity. The catalyst can be recovered by simple filtration and shows very high reusability. The high activity depicted by the supported catalyst and its chemical and mechanical stability have allowed its application in packed-bed reactors for continuous flow processing. This system can produce enantio- and diastereomerically pure aldol adducts under continuous flow conditions with a residence time of 26 min. Furthermore, the reactor allowed processing of four different aldol products in sequence without any decrease in both catalytic activity and optical purity. The effective catalyst loading could be reduced to 1.6% (six-fold reduction of catalyst loading compared to the corresponding batch process).

A solid-supported organocatalyst for continuous-flow enantioselective aldol reactions.

Stable and easily synthesized metal-organic framework MIL-88B-NH2 represents an attractive support for catalysts employed in oxidation reactions, which are typically performed under relatively hars ...

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Double-Supported Silica-Metal–Organic Framework Palladium Nanocatalyst for the Aerobic Oxidation of Alcohols under Batch and Continuous Flow Regimes

The preparation through Robinson annulation of enantiopure building blocks with both academic and industrial relevance, such as the Wieland–Miescher and Hajos–Parrish ketones, has suffered from important drawbacks, such as the need for high catalyst loading or extremely long reaction times. Here we report a heterogenized organocatalyst based on Luo’s diamine for fast and broad-scope enantioselective Robinson annulation reactions. The polystyrene-supported diamine 19a enables the high-yield, highly enantioselective preparation of a wide range of chiral bicyclic enones under mild conditions, with reaction times as short as 60 min (batch) or residence times of 10 min (flow). In contrast with its homogeneous counterpart 19b, the catalytic resin 19a experiences a notable increase in catalytic activity with temperature in 2-MeTHF (a 10-fold decrease in reaction times without erosion in enantioselectivity is observed from room temperature to 55 °C). The scope of the transformation in batch mode has been illustra...

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A Highly Active Polymer-Supported Catalyst for Asymmetric Robinson Annulations in Continuous Flow

The pyrrolo[2,3-c]carbazole 1, the common core of the marine alkaloids known as the dictyodendrins, has been synthesised. The sequence is based on a Suzuki cross-coupling reaction between the pyrrole fragment 2 and the indole fragment 3, followed by tandem photochemical 6π-electrocyclisation/aromatisation.

Synthesis of the pyrrolo[2,3-c]carbazole core of the dictyodendrins.

Two alternative syntheses of the new D2d symmetric tetramethyl tricyclo[3.3.0.03,7]octane-1,3,5,7-tetracarboxylate from the known dimethyl 3,7-dioxo-cis-bicyclo[3.3.0]octane-1,5-dicarboxylate and 1,5-(2,2‘-biphenylene)-cis-bicyclo[3.3.0]octane-3,7-dione are described.

Carles Ayats

Papers

A solid-supported organocatalyst for continuous-flow enantioselective aldol reactions.

Double-Supported Silica-Metal–Organic Framework Palladium Nanocatalyst for the Aerobic Oxidation of Alcohols under Batch and Continuous Flow Regimes

A Highly Active Polymer-Supported Catalyst for Asymmetric Robinson Annulations in Continuous Flow

Synthesis of the pyrrolo[2,3-c]carbazole core of the dictyodendrins.

Alternative Syntheses of the New D2d Symmetric Tetramethyl Tricyclo- [3.3.0.03,7]octane-1,3,5,7-tetracarboxylate