Novel synthesis of meso-tetraarylporphyrins using CF3SO2Cl under aerobic oxidation

Application of novel silica stabilized on a covalent triazine framework as a highly efficient heterogeneous and recyclable catalyst in the effective green synthesis of porphyrins

In this study, we present the design, synthesis, and utilization of a covalent triazine framework (CTF) formed by the condensation of N 2,N 4,N 6-tris(4-(aminomethyl)benzyl)-1,3,5-triazine-2,4,6-triamine and 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine on which silica is immobilized (TPT-TAT/silica) as an innovative catalyst for porphyrins synthesis. Under solvothermal conditions, the condensation of triamine and trialdehyde precursors led to the formation of a covalent triazine framework (CTF) with a high nitrogen content. The resulting CTF is characterized by its extensive porosity and elevated nitrogen levels, which are critical for the creation of catalytic active sites. This framework demonstrated exceptional catalytic performance in the synthesis of porphyrins. Substituting aerobic conditions in lieu of costly oxidizing agents represents a significant advancement in our methodology. Due to the insolubility of the catalyst, it is possible to separate it from the reaction mixture through filtration or centrifugation. This property enhances its reusability and minimizes waste generation. This development in the synthesis and application of CTFs could pave the way for more sustainable and cost-effective catalytic processes in organic synthesis, particularly in the synthesis of complex molecules like porphyrins. The research highlights the potential of CTFs as versatile materials in catalysis, owing to their structural properties and the ability to tailor their functionalities for specific applications.

A method to determine the correct photocatalyst concentration for photooxidation reactions conducted in continuous flow reactors

When conducting a photooxidation reaction, the key question is what is the best amount of photocatalyst to be used in the reaction? This work demonstrates a fast and simple method to calculate a reliable concentration of the photocatalyst that will ensure an efficient reaction. The determination is based on shifting the calculation away from the concentration of the compound to be oxidized to utilizing the limitations on the total light dose that can be delivered to the catalyst. These limitations are defined by the photoflow setup, specifically the channel height and the emission peak of the light source. This method was tested and shown to work well for three catalysts with different absorption properties through using LEDs with emission maxima close to the absorption maximum of each catalyst.

β-Formyl- and β-Vinylporphyrins: Magic Building Blocks for Novel Porphyrin Derivatives

Porphyrins bearing formyl or vinyl groups have been explored as starting materials to prepare new compounds with adequate features for different applications. In this review it is discussed mainly synthetic strategies based on the reaction of meso-tetraarylporphyrins bearing those groups at β-pyrrolic positions. The use of some of the obtained porphyrin derivatives for further transformations, namely via pericyclic reactions, is also highlighted.

Synthesis of meso-tetraarylporphyrins using hafnium (IV) bis(perfluorooctanesulfonyl)imide complex in perfluorodecalin medium

This letter presents a non-conventional synthesis of meso-porphyrins in moderate yields, using catalytic quantities of hafnium (IV) bis(perfluorooctanesulfonyl)imide complex in a perfluorodecalin biphasic system. Various meso-tetraarylporphyrins were obtained in good yields. The catalyst is selectively dissolved in perfluorodecalin, and can be recovered simply by phase separation and reused several times without any obvious decrease of activity.

Immobilized Lignin Peroxidase-Like Metalloporphyrins as Reusable Catalysts in Oxidative Bleaching of Industrial Dyes

Synthetic and bioinspired metalloporphyrins are a class of redox-active catalysts able to emulate several enzymes such as cytochromes P450, ligninolytic peroxidases, and peroxygenases. Their ability to perform oxidation and degradation of recalcitrant compounds, including aliphatic hydrocarbons, phenolic and non-phenolic aromatic compounds, sulfides, and nitroso-compounds, has been deeply investigated. Such a broad substrate specificity has suggested their use also in the bleaching of textile plant wastewaters. In fact, industrial dyes belong to very different chemical classes, being their effective and inexpensive oxidation an important challenge from both economic and environmental perspective. Accordingly, we review here the most widespread synthetic metalloporphyrins, and the most promising formulations for large-scale applications. In particular, we focus on the most convenient approaches for immobilization to conceive economical affordable processes. Then, the molecular routes of catalysis and the reported substrate specificity on the treatment of the most diffused textile dyes are encompassed, including the use of redox mediators and the comparison with the most common biological and enzymatic alternative, in order to depict an updated picture of a very promising field for large-scale applications.

Nanoporous iron(iii) porphyrin frameworks: an efficient catalyst for [4+2] cycloaddition reactions of unactivated aldehydes with a diene

The one pot conversion of several unactivated aldehydes with a diene to their corresponding [4+2] cycloaddition products has been studied using nanoporous iron(iii) porphyrin frameworks as catalysts.

Synthetic transformations of porphyrins – Advances 2002-2004

Contemporary methods for the modification of porphyrins are presented. In association with the Third International Conference on Porphyrins and Phthalocyanines (ICPP-3) a survey of current method developments and reactivity studies is made. The review focuses on synthetic transformations of porphyrins currently in use for various applications and on functional group transformations. A brief survey of important developments covers selectively the literature from late 2001 to early 2004.

Synthesis of novel lipophilic porphyrin-cardanol derivatives

The synthesis of new lipophilic meso-tetraarylporphyrins bearing cardanol is described; cardanol is both a dangerous pollutant and renewable, widely available, relatively low-cost natural material obtained as a byproduct of the cashew industry for the edible use of cashew kernel. Such compounds exhibited unusual chemical and physico-chemical properties.

Solvent-free synthesis of meso- tetraarylporphyrins in air: product diversity and yield optimization

The scope and optimization of a solvent-free method for the rapid preparation and facile purification of technologically important meso-substituted aryl porphyrins, such as 5,10,15,20-tetraphenylporphyrin is presented. This one-step method involves heating the aromatic aldehyde to ~200°C in a vial fitted with a septum-lined cap, followed by addition of the pyrrole and maintaining the temperature for about 20 minutes. The dioxygen in air serves as the oxidant. Present results show that the addition of benzoic acid as a catalyst improves the yield of 5,10,15,20-tetraphenylporphyrin from 22% to 32% and of para halogenated phenylporphyrins from 10% to ~25%. Herein is also presented an examination of the many factors that influence the yield, the ease of purification, and the ability to scale up the reaction. Since the tarry by-products from this method are much less soluble than in most other synthetic strategies, much less solvent is required for purification; simple extraction is often sufficient. This method can be scaled in the lab to > 300 mg, and provides an attractive route to many meso-substituted porphyrins because of its minimal waste generation in terms of both solvent and chromatography support.

Porphyrins as Molecular Electronic Components of Functional Devices

The proposal that molecules can perform electronic functions in devices such as diodes, rectifiers, wires, capacitors, or serve as functional materials for electronic or magnetic memory, has stimulated intense research across physics, chemistry, and engineering for over 35 years. Because biology uses porphyrins and metalloporphyrins as catalysts, small molecule transporters, electrical conduits, and energy transducers in photosynthesis, porphyrins are an obvious class of molecules to investigate for molecular electronic functions. Of the numerous kinds of molecules under investigation for molecular electronics applications, porphyrins and their related macrocycles are of particular interest because they are robust and their electronic properties can be tuned by chelation of a metal ion and substitution on the macrocycle. The other porphyrinoids have equally variable and adjustable photophysical properties, thus photonic applications are potentiated. At least in the near term, realistic architectures for molecular electronics will require self-organization or nanoprinting on surfaces. This review concentrates on self-organized porphyrinoids as components of working electronic devices on electronically active substrates with particular emphasis on the effect of surface, molecular design, molecular orientation and matrix on the detailed electronic properties of single molecules.