Sustainable Strategy for Microplastic Mitigation: Fe3O4 Acid-Functionalized Magnetic Nanoparticles for Microplastics Removal Ivanilson da Silva de Aquino, Ester de Araújo Freire, Alisson Mendes Rodrigues, Otilie Eichler Vercillo, Mauro Francisco Pinheiro da Silva, et al. Sustainability Switzerland, 2025 Microplastic (MPs) pollution has emerged as a critical environmental issue due to its persistent accumulation in ecosystems, posing risks to aquatic life, food safety, and human health. In this study, magnetic Fe3O4 nanoparticles functionalized with citric acid (Fe3O4@AC) were used to remove high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) MPs from an aqueous medium. Fe3O4@AC was synthesized via the coprecipitation method and characterized by morphology (SEM), crystalline phases (XRD), chemical aspects (FTIR), and surface area (nitrogen sorption isotherms). The MPs removal efficiency of Fe3O4@AC was evaluated based on the initial concentration, contact time, and pH. The adsorption isotherm and kinetics data were best described by the Sips and pseudo-second-order models, respectively. Fe3O4@AC removed 80% of the MPs at a pH of 6. Based on experimental observations (zeta potential, porosity, and SEM) and theoretical insights, it was concluded that hydrogen bonding, pore filling, and van der Waals forces governed the adsorption mechanism. Reusability tests showed that Fe3O4@AC could be reused up to five times, with a removal efficiency above 50%. These findings suggest that Fe3O4@AC is a sustainable and promising material for the efficient removal of microplastics from wastewater, offering a reusable and low-impact alternative that contributes to environmentally responsible wastewater treatment strategies.
Consecutive isocyanide-based multicomponent reactions: Synthesis of cyclic pentadepsipeptoids Angélica de Fátima S Barreto, Otilie E Vercillo, Ludger A Wessjohann, Carlos Kleber Z Andrade Beilstein Journal of Organic Chemistry, 2014 The synthesis of six cyclic depsipeptoids inspired by the natural depsipeptide sansalvamide A is described. An efficient and fast synthetic strategy was developed using a combination of consecutive isocyanide-based multicomponent reactions (Ugi and Passerini reactions). This methodology can be used to access a variety of cyclic oligodepsipeptoids.
Fast and efficient microwave-assisted synthesis of functionalized peptoids via Ugi reactions Angélica de Fátima S. Barreto, Otilie E. Vercillo, Mike A. Birkett, John C. Caulfield, Ludger A. Wessjohann, et al. Organic and Biomolecular Chemistry, 2011 A wide range of N-alkylglycines (peptoids) can be efficiently prepared via Ugi reactions using microwave irradiations. The results confirm the versatility and efficiency of the methodology for the preparation of functionalized peptoids. The products can be used in consecutive Ugi reactions to yield cyclic peptoids of potential biological interest.
Microwave-assisted Passerini reactions under solvent-free conditions Angélica de Fátima S Barreto, Otilie E Vercillo, Carlos Kleber Z Andrade Journal of the Brazilian Chemical Society, 2011 Various a-acyloxy carboxyamides were easily obtained combining three building blocks in one step: a carboxylic acid, an aldehyde and an isonitrile (Passerini reaction), using microwave irradiation under solvent-free conditions. The products were obtained in good yields (61-90%) and in short reaction times (≤ 5 min), using two different temperatures (60 and 120 °C). At 120 °C, the yields were higher and the reactions faster (≤ 1 min). Most of the obtained products are multifunctional allowing their application in consecutive Passerini reactions.
Multiple multicomponent macrocyclizations (MiBs): A strategie development toward macrocycle diversity Ludger A. Wessjohann, Daniel G. Rivera, Otilie E. Vercillo Chemical Reviews, 2009 Macrocycles are of high significance in areas as diverse as drug development and supramolecular chemistry. They can be considered as privileged molecules because they can combine flexibility and conformational bias. They allow a certain conformational adaptation for binding and at the same time can have an improved overall energy term while binding, compared to linear molecules. Recently, a diversityoriented macrocyclization strategy termed multiple multicomponent macrocyclization including bifunctional building blocks (MiB) was developed which allows producing constitutionally diverse and complex macrocycles from simple building blocks in one pot. The efficient search for novel molecular ligands of biological targets remains a continuing goal in drug discovery and chemical biology.1-3 In the past, the predominant interest of medicinal chemists in synthetic ligands has been devoted to small rings (especially heterocycles) because of their known capability to interact with defined protein motifs and their ease of preparation. Huge libraries, including combinatorial ones,4,5 have been synthesized by means of wellestablished processes and screened for biological activity. Lately, macrocycles have attracted increasing attention also by virtue of both their high success rate in medicinal and recognition chemistry and their widespread occurrence in nature.6-10 The demand for bioactive compounds with new application profiles has triggered the search for molecules with biological features that simple 5/6/7-ring (hetero)cycles do not bear.8-12 Macrocycles are usually endowed with a proper combination of more than one binding domain, conformational preorganization, and flexibility.8,13,14 Their structural, physicochemical, and biological features provide recognition and binding properties not found in linear or small ring counterparts.14 For example, their often increased biological stability compared to acyclic analogues (e.g., cyclopeptides compared to peptides) makes them a fascinating paradigm to design biologically active molecules.8-14 Combinatorial synthetic chemistry in the macrocycle field does not yet reflect the tremendous impact of naturally occurring macrocycles in areas such as antibiotics, immunosuppressants, ion chelators, or membrane active compounds, where their success rate appears to be overproportional (in relative terms) compared to other drug types.6-9,15
Rapid generation of macrocycles with natural-product-like side chains by multiple multicomponent macrocyclizations (MiBs) Daniel G. Rivera, Otilie E. Vercillo, Ludger A. Wessjohann Organic and Biomolecular Chemistry, 2008 A small parallel library of peptoid macrocycles with natural-product-derived side chains of biological importance was produced by Ugi-type multiple multicomponent macrocyclizations including bifunctional building blocks (Ugi-MiBs). Diverse exocyclic elements of high relevance in natural recognition processes, i.e., all functional amino acid residues (e.g., Cys, Arg, His, Trp) and even sugar moieties, can be introduced in a one-pot process into different types of peptoid-containing macrocyclic skeletons. This is exemplified by the use of a diamine/diisocyanide combination of Ugi-MiBs and N-protected alpha-amino acids or carboxy-functionalized carbohydrates as source for the natural-product-like exocyclic elements. Employed as the acid components of the multiple Ugi reactions, they appear as N-amide substituents on the macrocyclic cores. The use of different diamines and diisocyanides allows an easy variation of the N- to C-directionality and therefore of the position of the exocyclic elements.
Design and synthesis of cyclic RGD pentapeptoids by consecutive Ugi reactions Otilie E. Vercillo, Carlos Kleber Z. Andrade, Ludger A. Wessjohann Organic Letters, 2008 A new strategy for the synthesis of cyclic peptoids was developed. The approach is based on the use of consecutive Ugi reactions for the assembly of the acyclic peptoid and for the ring closure. Cyclopentapeptoid analogues of the RGD peptides were designed and synthesized using this methodology. The results confirm the versatility and efficiency of the method for the preparation of cyclic oligopeptoids.
Combinatorial synthesis of macrocycles by multiple multicomponent macrocyclization including bifunctional building blocks (MiB) Ludger Wessjohann, Daniel Rivera, Otilie Vercillo Synlett, 2007 Small libraries of peptoid-based macro(multi)cycles were produced by applying combinatorial principles to the MiB methodology. This combinatorial approach features the incorporation of varied building blocks into the resulting macrocycles by mixing all the components in the same reaction pot. Both skeletal and appendage diversity could be generated in one shot due to the multicomponent nature of the system. HPLC and ESI-MS analyses showed a well-distributed composition of the libraries and revealed the presence of all possible macrocycles resulting from the different combinations of building blocks, especially of members with differentially substituted bridges not available by any other one-pot approach.
Intramolecular ene reactions catalyzed by NbCl5, TaCl 5 and InCl3 Carlos Kleber Z. Andrade, Otilie E. Vercillo, Juliana P. Rodrigues, Denise P. Silveira Journal of the Brazilian Chemical Society, 2004 Pentacloreto de niobio, pentacloreto de tântalo e tricloreto de indio catalisaram eficientemente a ciclizacao do (R)-citronelal a uma mistura de isopulegol e neoisopulegol, em bons rendimentos. Um estudo comparativo foi realizado demonstrando que NbCl5 e o acido de Lewis mais ativo enquanto que InCl3 e o mais seletivo. A seletividade das reacoes variou de acordo com o acido de Lewis utilizado e o solvente. NbCl5 e TaCl5 mostraram ausencia de seletividade enquanto que o InCl3 apresentou seletividade moderada em favor do isopulegol. A reacao ene de um 1,7-dieno tambem foi investigada. Neste caso, todos os acidos de Lewis testados apresentaram excelente seletividade.
