Synthesis and stereochemical studies of di and tetra 9,9′-spirobifluorene porphyrins: new building blocks for catalytic material

Porphyrin Atropisomerism as a Molecular Engineering Tool in Medicinal Chemistry, Molecular Recognition, Supramolecular Assembly, and Catalysis

Porphyrin atropisomerism, which arises from restricted σ-bond rotation between the macrocycle and a sufficiently bulky substituent, was identified in 1969 by Gottwald and Ullman in 5,10,15,20-tetrakis(o-hydroxyphenyl)porphyrins. Henceforth, an entirely new field has emerged utilizing this transformative tool. This review strives to explain the consequences of atropisomerism in porphyrins, the methods which have been developed for their separation and analysis and present the diverse array of applications. Porphyrins alone possess intriguing properties and a structure which can be easily decorated and molded for a specific function. Therefore, atropisomerism serves as a transformative tool, making it possible to obtain even a specific molecular shape. Atropisomerism has been thoroughly exploited in catalysis and molecular recognition yet presents both challenges and opportunities in medicinal chemistry.

TfOH-Catalyzed Intramolecular Annulation of 2-(Aryl)-Phenyl-Substituted p-Quinone Methides under Continuous Flow: Total Syntheses of Selaginpulvilin I and Isoselagintamarlin A

In this article, we describe a convenient method to access 9-aryl fluorene derivatives through a TfOH-catalyzed intramolecular 1,6-conjugate arylation of 2-(aryl)-phenyl-substituted p-quinone methides (QMs) under continuous flow using the microreaction technique. This method was found to be very effective for most of the p-QMs, and the corresponding 9-aryl fluorene derivatives were obtained in moderate to excellent yields. Moreover, this protocol was further elaborated to the first total syntheses of selaginpulvilin I and isoselagintamarlin A.

New generations of spirobifluorene regioisomers for organic electronics: tuning electronic properties with the substitution pattern

In the present feature article, we present the new generations of spirobifluorenes for organic electronics and we detail the impact of positional isomerism on the electronic properties and device performance.

Hole transporting materials for perovskite solar cells: a chemical approach

Photovoltaic solar cells based on perovskites have come to the forefront in science by achieving exceptional power conversion efficiencies (PCEs) in less than a decade of research. This "still young" generation of solar cells is currently rivalling, in PCEs, well-established technologies, such as cadmium telluride (CdTe) and silicon. Further improvements in device stability by means of innovative materials are yet to come, with technology becoming closer to meeting the market requirements. Emerging from this groundbreaking discovery, a great number of charge transporting materials have flourished, which is particularly true for hole transporting materials (HTMs). The huge number of molecules prepared stem from design and engineering of a wide variety of new and also chemically modified old molecules where organic synthesis has played a fundamental role. In this review, the contribution of chemistry through those synthetic protocols used for producing new and innovative HTMs from relatively simple organic molecules is presented in a rational and systematic manner. The variety and impact of synthetic strategies followed, the structure-property relationship and stability, conductivity and device performance are highlighted from a chemical viewpoint.

Fluorenone synthesis by palladacycle-catalyzed sequential reactions of 2-bromobenzaldehydes with arylboronic acids

A new, anionic four-electron donor-based (type I) palladacycle-catalyzed sequential reaction of 2-bromobenzaldehydes with arylboronic acids based on the addition reaction, cyclization via C-H activation-oxidation sequence is described. Our study provided an efficient access to a variety of substituted fluorenones/indenofluorenediones from readily available arylboronic acids and 2-bromobenzaldehydes.

Organic Cross-Linked Electropolymers as Supported Oxidation Catalysts: Poly((tetrakis(9,9‘-spirobifluorenyl)porphyrin)manganese) Films

Anodic oxidation of free base and manganese complexes of tetraspirobifluorenylporphyrins leads to the coating of the working electrode by insoluble electroactive poly(9,9'-spirobifluorene-free and manganese porphyrin) films which electrochemical behavior and physicochemical properties are described. After removal from the electrode, the manganese-complexed polymers were evaluated as catalysts for the oxidation of alkenes by iodobenzene diacetate or iodosylbenzene. The results show that the reactions proceeded very efficiently at room temperature with good yields. The electrosynthesized polymer catalysts can be recycled by simple filtration and reused even up to the eighth cycle without loss of activity and selectivity. These results represent an important improvement over those previously described for manganese-porphyrin-catalyzed epoxidation reactions.