The imidazole (IMZ) ring presents several chemical properties that turns it into a versatile acid-basic/nucleophilic catalyst. The discovery of the biological properties of histidine (amino acid with IMZ ring) instigates the study of this class of compounds. It is found in nature in several enzymes such as chymotrypsin and RNAses due to these properties. This review is focused on the catalytic role of IMZ towards the cleavage of acyl and phosphate esters and is structured in the following topics: chemical properties, biological catalysis (RNAses, phosphohistidines, chymotrypsin), intermolecular and intramolecular catalytic models and polymer and nanomaterials-based catalysts. Besides we discuss some properties such as tautomerism, stability, basicity and spectroscopic behavior, correlating with its reactivity in deacylation and dephosphorylation reactions. The main reaction mechanisms and kinetics promoted by IMZ as an acid, basic and nucleophilic catalysts are explored showing some examples. In addition, the importance of IMZ in enzymatic sites and their mechanisms and further combining properties of IMZ with some materials such as (bio)polymers, graphene, and cyclodextrines are covered. In this sense, with the wide IMZ data presented here, we are evidencing the perfect match between IMZ and catalysis.

Brazil’s gender gaps numbers are scarce in the field of chemistry. Thus, the motivation of this work is to perform a data survey considering all levels of the academic career and per Brazilian region. The data collected shows a general trend observed in all scenarios, whereas the higher the career level the lower the number of women inserted. Women dominate in the early stages of the scientific careers, such as postgraduate programs (52%) but become minority (42%) when they get positions as university professors. The disparity is higher at positions of great recognition, e.g., member of the Brazilian Academy of Science (18%) or the highest level of CNPQ research productivity fellowship “1A” (12%). Other career indicators such as research grants approval, authorship in recognized international journals and in highly cited articles authored by Brazilian scientists, show low female representativity. Leadership positions in scientific societies and funding agencies are alarming (6%), where many organizations never had a woman president. The world needs more female references in science and surely Brazil has many great women in the field of chemistry that deserve recognition. The present study sheds light to the awareness of the Brazilian scenario.

Is the broad mechanistic versatility of imidazole towards organophosphates (OPs), that has inspired many catalysts and sensors, beneficial? Herein, a thorough analysis is given seeking to unravel this puzzle. For OPs from the P=O family, imidazole attacks the phosphorus atom exclusively (N-phosphorylates). With the P=S family which are less reactive, an unusual N-alkylation predominates. Surprisingly, imidazole reacts with methyl parathion exclusively at the aliphatic carbon, whilst for the ethylated analogue parathion, imidazole reacts by two pathways: at both the phosphorus and aliphatic carbon, with predominance for the latter. The preference for the electrophilic center can be modulated by the pH. Overall, a mechanistic structure-related trend is observed: imidazole tends to prefer other electrophilic centers than the phosphorus for less reactive OPs. Moreover, this gives important insights concerning the challenging chemistry of imidazole alkylation and the outcomes for monitoring systems that depend on the detection of degradation products. Finally, a thorough comparison with the literature is presented seeking to understand how imidazole reacts towards various OPs. We suggest that the promiscuity of imidazole boosts up its versatility.

Undoubtedly, the chemical element carbon is strategic for the development of any country and herein we show some specific impacts in the economical, industrial and scientific sovereignty of Brazil, with emphasis on sp2 carbn structures, namely graphite, carbon black, carbon nanotubes and graphene. Brazil comprises the second greatest natural reserve of graphite worldwide and ranks as third in world production. Carbon black also has important industrial impact in Brazil, especially in the automobile industry, specifically in tires. Some of world leading companies in the production of carbon black are installed in Brazil. Finally, carbon nanotubes and graphene are addressed as the next generation of materials that have and will have great impact in the next years. Their impressive properties have enabled innumerous commercial products worldwide and Brazil already stands out with some innovative initiatives. Indeed, Brazil has installed capacity in universities and research institutes to meet and foster demands in the area, and can be competitive worldwide.

Rice husk (RH) is one the largest agricultural waste products worldwide, and rice is one of the crops that use the most pesticides. Among these, organophosphates have been of increasing concern due to their high toxicity. Herein, we report the functionalization of RH with imidazole groups (RHIMZ) to obtain sustainable catalysts from waste for organophosphate degradation. The waste-derived catalyst showed prominent catalytic activity in dephosphorylation reactions with the model substrate diethyl 2,4-dinitrophenyl phosphate (DENDPP), over 105-fold, compared to the spontaneous reaction (lifetime = 1 month). Finally, RHIMZ was also effective in degrading the pesticide Paraoxon (spontaneous lifetime = 1 million years), degrading 60% in 20 days, giving a 107-fold enhancement. Overall, the proposed approach is environmentally friendly for reusing the waste for a noble cause, i.e., degrading toxic pesticides, which is promising for designing sensors and detoxification processes.

Herein, we propose an interdisciplinary experiment for undergraduate course that involves concepts of organic and physical chemistry. Firstly, we propose the synthesis of three nitrophenyl acetates, varying the substituent position. Afterwards, we describe the construction of a homemade colorimeter using inexpensive materials and LED as both emission and detection dispositives. Finally, the colorimeter is used to follow the nucleophilic acyl transfer reactions catalyzed by imidazole under pseudo-first order conditions for the reactions of p-nitrophenyl, o-nitrophenyl and m-nitrophenyl acetate with imidazole. The substituent effect is correlated to the reactivity of the acetates, one of the benchmarks of a physical organic chemical approach. The effect of imidazole concentration is also evaluated. The proposed experiment is interesting because the students can thoroughly understand how a spectrophotometer works and since each student can construct their own colorimeter, they don't have to rely on any equipment infrastructure. Additionally they can correlate two important areas: organic and physical chemistry by using a kinetic study in the understanding of organic reactions. Indeed, physical organic chemistry is a field of increasing interest specially for elucidating mechanisms and introducing students to this interdisciplinary approach is interesting since several undergraduate concepts are covered.

Results confirm the catalytic potential of imidazole groups anchored on the polymeric backbone of polyvinylimidazole (PVI) in dephosphorylation reactions with di- and tri-phosphoesters, promoting impressive enhancements up to 107-fold. We propose the imidazole groups on PVI react by nucleophilic catalysis (neutral specie) with a phosphate triester and bifunctionally by general acid-nucleophilic catalysis (bipolar species) with a diester. Additionally, PVI can incorporate the reactants on its domains by hydrophobic and electrostatic attraction, confirming the polymer multifunctionality. Moreover, a pronounced micellar catalysis was observed for the reactions which, surprisingly, occurs with both cationic and anionic micelles, due to favorable approximation effects. The micellar effects observed confirms the reactivity of the bipolar species. Based on the pseudophase model, the reagents can be incorporated in the micellar phase, mainly by hydrophobic forces. Overall, we confirm that PVI has great potential as an artificial enzyme, since it undergoes enzymatic-like mechanisms with an elegant bifunctional catalysis.

A reação entre um novo derivado de imidazol, 3,5-bis((1H-imidazol-1-il)metil)anilina (BIm), e o triéster de fosfato dietil 2,4-dinitrofenil fosfato (DEDNPP), que procede por um mecanismo SN2(P), é substancialmente acelerada em presença do surfactante catiônico brometo de cetiltrimetrilamônio (CTAB) e do surfactante aniônico dodecil sulfato de sódio (SDS). Tal efeito micelar atípico ilustra o emprego de efeitos hidrofóbicos dos reagentes para otimizar o efeito catalítico de micelas aquosas. Tal observação é importante e útil no planejamento de modelos miméticos de reações biológicas, já que a melhoria da incorporação dos reagentes aumentará efetivamente a qualidade dos sistemas biomiméticos, sendo que ambos os surfactantes catiônico e aniônico poderão atuar como nanoreatores homogêneos, concentrando os reagentes neutros hidrofóbicos.

The reaction of a new imidazole derivative, 3,5-bis((1H-imidazol-1-yl)methyl)aniline (BIm), and the model triester diethyl 2,4-dinitrophenyl phosphate (DEDNPP), which proceeds via a SN2(P) mechanism, is substantially enhanced in the presence of either cationic cetyltrimethylammonium bromide (CTAB) or anionic sodium dodecyl sulfate (SDS). This unusual micellar effect illustrates the use of the hydrophobic character of the reactants to enhance micellar catalysis. This is an important and useful guideline in planning mimics for biological reactions, because improving incorporation will increase the quality of the biomimetic systems, and both cationic or anionic surfactants will act as homogeneous nanoreactors concentrating the neutral, hydrophobic reactants.