The use of small organic molecules as catalysts has gained increasing importance recently. These substances, the so-called organocatalysts, present a lot of advantages, like being less toxic, less polluting, and more economically viable than the organometallic catalysts that dominate asymmetric synthesis. This work intends to briefly show some classic works and recent publications, explaining the advantages of organocatalysis and the different types of compounds used in this field, as well as their course of action.

Simple methodologies giving access to a new series of pophyrin/4-quinolone conjugates 6 and to the corresponding intra-cyclized derivatives 8 are described. The key steps to obtain 6 involved palladium-catalyzed amination reactions of 6-bromo-4-quinolones containing N-ethyl, N-pentyl and N-ribofuransyl substituents with (2-amino-5,10,15,20-tetraphenylporphyrinato)nickel(II) followed by demetallation. Compounds 8 were obtained from compounds 4, the nickel(II) complexes of 6, by an oxidative intracylization approach. The new conjugates were fully characterized and the evaluation of singlet oxygen production showed that these compounds possess good to high capability to generate singlet oxygen. The efficacy of these derivatives to photoinactivate Staphylococcus aureus, a Gram-positive bacteria, was evaluated and the best results were obtained with the N-ethyl derivatives 8a and 6a.

Carbene transfer reactions are very important transformations in organic synthesis, allowing the generation of structurally challenging products by catalysed cyclopropanation, cyclopropenation, carbene C-H, N-H, O-H, S-H, and Si-H insertion, and olefination of carbonyl compounds. In particular, chiral and achiral metalloporphyrins have been successfully explored as biomimetic catalysts for these carbene transfer reactions under both homogeneous and heterogeneous conditions. In this work the use of synthetic metalloporphyrins (MPorph, M = Fe, Ru, Os, Co, Rh, Ir, Sn) as homogeneous or heterogeneous catalysts for carbene transfer reactions in the last years is reviewed, almost exclusively focused on the literature since the year 2010, except when reference to older publications was deemed to be crucial.

Dye-sensitized solar cells (DSSCs) have emerged as a promising alternative in photovoltaic energy, owing to their efficiency, cost-effectiveness, and versatility. Sensitizers are crucial in efficiently converting solar energy into electricity in these systems. This review focuses on employing coumarins, a class of aromatic organic compounds, as sensitizers in DSSCs. We address the synthesis of coumarins, their photophysical and electronic properties, and their application in optimizing the energy conversion efficiency of DSSCs. We explore the molecular engineering strategies used to improve the properties of coumarins, including structural modification and the combination with other materials. Furthermore, we discuss current challenges and prospects for the development of DSSCs using coumarins as sensitizers. This review aims to provide a comprehensive overview of the current state and future directions of this exciting area of solar energy research.

Oral squamous cell carcinoma (OSCC) is a global public health problem with high incidence and mortality. The chemotherapeutic agents used in the clinic, alone or in combination, usually lead to important side effects. Thus, the discovery and development of new antineoplastic drugs are essential to improve disease prognosis and reduce toxicity. In the present study, acridine-core naphthoquinone compounds were synthesized and evaluated for their antitumor activity in OSCC cells. The mechanism of action, pharmacokinetics, and toxicity parameters of the most promising compound was further analyzed using in silico, in vitro, and in vivo methods. Among the derivatives, compound 4e was highly cytotoxic (29.99 µM) and selective (SI 2.9) at levels comparable and generally superior to chemotherapeutic controls. Besides, compound 4e proved to be non-hemolytic, stable, and well tolerated in animals at all doses tested. Mechanistically, compound 4e promoted cell death by apoptosis in the OSCC cell, and molecular docking studies suggested this compound possibly targets enzymes important for tumor progression, such as RSK2, PKM2, and topoisomerase IIα. Importantly, compound 4e presented a pharmacological profile within desirable parameters for drug development, showing promise for future preclinical trials.