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Reverse micelles as nanosized aqueous droplets existing at certain compositions of water-in-oil microemulsions are widely used today in the synthesis of many types of nanoparticles. However, without a rich conceptual network that would correlate the properties and compositions of reverse micellar microemulsions to the properties of to-be-obtained particles, the design procedures in these cases usually rely on a trial-and-error approach. As like every other science, what is presently known is merely the tip of the iceberg compared to the uninvestigated vastness still lying below. The aim of this article is to present readers with most of the major achievements from the field of materials synthesis within reverse micelles since the first such synthesis was performed in 1982 until today, to possibly open up new perspectives of viewing the typical problems that nowadays dominate the field, and to hopefully initiate the observation and generation of their actual solutions. We intend to show that by refining the oversimplified representations of the roles that reverse micelles play in the processes of nanoparticles synthesis, steps toward a more complex and realistic view of the concerned relationships can be made.

The first two sections of the review are of introductory character, presenting the reader with the basic concepts and ideas that serve as the foundations of the field of reverse micellar synthesis of materials. Applications of reverse micelles, other than as media for materials synthesis, as well as their basic structures and origins, together with experimental methods for evaluating their structural and dynamic properties, basic chemicals used for their preparation and simplified explanations of the preparation of materials within, will be reviewed in these two introductory sections. In Secs. 3 and 4, we shall proceed with reviewing the structural and dynamic properties of reverse micelles, respectively, assuming that knowledge of both static and dynamic parameters of microemulsions and changes induced thereof, are a necessary step prior to putting forth any correlations between the parameters that define the properties of microemulsions and the parameters that define the properties of materials synthesized within. Typical pathways of synthesis will be presented in Sec. 5, whereas basic parameters used to describe correlations between the properties of microemulsion reaction media and materials prepared within, including reagent concentrations, ionic strength, temperature, aging time and some of the normally overlooked influences, will be mentioned in Sec. 6. The whole of Sec. 7 is devoted to reviewing water-to-surfactant molar ratio as the most often used parameter in materials design by performing reverse micellar synthesis routes. The mechanisms of particle formation within precipitation synthesis in reverse micelles is discussed in Sec. 8. Synthesis of composites, with special emphasis on silica composites, is described in Sec. 9. All types of materials, classified according to their chemical compositions, that were, to our knowledge, synthesized by using reverse micelles up-to-date, will be briefly mentioned and pointed to the corresponding references in Sec. 10. In Sec. 11, some of the possible future directions for the synthesis of nanostructured materials within reverse micelles, found in combining reverse micellar syntheses and various other synthesis procedures with the aim of reaching self-organizing nanoparticle systems, will be outlined.

The relaxor ferroelectric Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ compositions are of interest owing to their excellent dielectric, electromechanical, electro-optical, and other properties. In this paper, the 0.80Pb(Mg_1/3Nb_2/3)O₃–0.20PbTiO₃ (PMN–PT 80/20) films with pure perovskite structure were synthesized by a single step at 150°C. The corresponding oxides were used as starting materials, namely PbO, MgO, Nb₂O₅, and TiO₂. By using oxides as precursors, we simplified the hydrothermal process, allowing the process to be more economical. The influences of the Ti metal substrate on the PMN–PT 80/20 films are investigated. By surveying the variations of films, it was suggested that the substrate reacted with the ions in the solution. The films were smooth and homogeneous. There were no cracks and abnormity crystals on the surface of the films. The thickness was about 20 μm. The frequencies dependence of the dielectric properties of PMN–PT 80/20 films was stable even at a high frequency range over 1 MHz.

4-Amino-decylpyridinium bromide (ADPBr), an antimicrobial surface active agent, was synthesized by quaternization of 4-aminopyridine (AP) with decyl bromide (DBr). The reaction was carried out at 1:1.2 molar ratio of reactants (4-aminopyridine and decyl bromide, respectively) at 200°C for 10 min. The maximum yield of the product was 74.6%. The structure of the synthesized product was characterized by using modern analytical techniques, such as FT-IR, ¹H NMR, and ¹³C NMR. The antimicrobial activity of the salt was evaluated with minimum inhibition concentration method and showed good activity against gram-negative bacteria. The MIC of the salt was found to be 600 ppm for 2 × 10⁴ CFU/mL of E. coli.

Inspired by nature, Metal-N₄-complexes have been utilized as potential models to catalyze the sluggish oxygen reduction reaction (ORR) at cathode in fuel cells. Herein, we designed and synthesized dibenzo-N₄-[14]annulene metal complexes of Fe^II and Co^II metal ions and their nanocomposites with carbon black and characterized by various techniques. Computational and spectroscopic results suggested that the prepared complexes have saddle octahedral geometry. Further, the electrocatalytic activity of prepared nanocomposites towards ORR was investigated by using cyclic and linear sweep voltammetric techniques. The results exhibited that these nanocomposites are significantly ORR active; however, Fe-nanocomposite showed high ORR activity as compared to Co-composite. Theoretical studies indicated that the HOMO of Fe-complex was very near to the antibonding LUMO orbitals of dioxygen as compared to Co-complex, endowing high ORR activity.

Novel zinc carboxylates metal–organic frameworks (Zn-MOFs) with different sizes and shapes constructed by Zn(II) ions, succinate and isonicotinate were synthesized by a polymer-assisted method. The samples were characterized by scanning electron microscope, powder X-ray diffraction and fluorescence spectroscopy. Results indicated that the size and shape of the Zn-MOFs could be adjusted by changing the quantity of polyvinyl alcohol (PVA). Fluorescence sensing of 2-nitrotoluene, 4-nitrotoluene and 2,4-dinitrotoluene was also studied and the results revealed that the as-prepared Zn-MOFs with a sheet-like shape were highly sensitive to nitro-compounds and promising to be developed as a novel luminescent sensor for detection in nitroaromatic explosives.

Calix[4]aren/mercaptopurine complex, scientifically called 1,7-dihydro-6h-purine-6-thione/calix[4]aren, is classified in the category of anticancer drugs. The stability properties structure of mercaptopurine complex with calix[4]aren was studied in dimethyl formamide, butanol, and butil eter solvents. Accordingly, these were investigated using the density functional theory (DFT) calculations at the B3LYP/6-31G (d) level and the degree of coverage of the atoms at the side effect C${}_{71}=$ S${}_{69}$ of pure and the complex mercaptopurine drugs. The main peak in the IR spectrum appeared in the 2149–2859cm${}^{-1}$ range. The molecular stability and no decay of structures were calculated and compared with each other by conducting both natural band orbital (NBO) and NMR calculations. Next, in the experimental section, the effect of drug complexation on its solubility rate in different solvents was investigated using the UV–Vis and solubility of the complex was higher in the dimethyl formamide solvent and its absorption intensity was 0.785. The changes in the intensity of the absorption peak in the XRD spectrum of both the pure and complex drug are in the range of 130 to 950.

Numerous sustainable water processing techniques have been widely investigated and are capable of boosting the quality of water. Among these techniques, photonanocatalysis has stood tall with great promises in the last few decades. Nonetheless, a major challenge in the environmental remediation of photocatalyst technology is to develop an ideal photocatalyst that must have excellent photocatalytic efficiency, large specific surface area, maximum harvesting of solar energy, high durability and recyclability. Due to their stability, low toxicity, low cost and superhydrophilicity TiO₂ has been used by researchers as an efficient photocatalyst for the degradation of organic pollutants. Unfortunately, it suffers greatly due to its high band gap with 3.2eV, insufficient visible light response, fast photogenerated electrons and holes recombination rate and serious agglomeration. Keeping these views, the present review highlights the principal results of studies on current practical synthesis and photocatalytic activity of graphene-based TiO₂ nanocomposite materials for the treatment of water. The amalgamation of graphene oxide (GO) and reduced graphene oxide (rGO) with nanoscale TiO₂ particles results in synergistic properties thereby tuning and increasing the functionality of the composite. In this regard, the review also addressed the progress and insight into graphene-based TiO₂ nanocomposite in photocatalytic removal of organic pollutants including basis mechanism, possible key strategies of the composite, and an overview of how to elevate efficacy. Finally, brief challenges and future perspectives in this field are also presented. Indeed, this work illustrated that graphene-based TiO₂ composite nanomaterials can be a green signal in the future of photocatalysis targeting water pollution remediation.

Cellulose with at least one of its dimensions less than or equal to 100 nm is termed as nanocellulose. It is a unique and promising natural material extracted from native cellulose and produced by certain microbial cells and cell-free systems. Nanocellulose has received immense consideration in last couple of decades owing to its abundance, renewability, remarkable physical properties, special surface chemistry, and excellent biological features (biocompatibility, biodegradability, and non-toxicity). Taking advantage of the structure and properties of nanocellulose, the current science of biomaterials aims at developing new and formerly non-existing materials with novel and multifunctional properties, in an attempt to meet current requirements in different fields such as biomedicine, the environment, energy, pharmaceutics, agriculture, food, etc. This chapter provides an overview of different synthesis methods of nanocellulose: mechanical approaches by applying high-pressure, grinding, crushing, sonication, and milling; chemical synthesis involving alkaline, acidic, oxidation, and enzymatic treatment; as well as by using bacteria and cell-free systems. It further discusses different morphological forms of nanocellulose including cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), bacterial nanocellulose (BNC), and cellulose produced by cell-free systems, in terms of their features such as chemical structure, macrostructural morphology, physico-mechanical properties, thermal and biological properties, rheology, optical behavior, and their interrelationships and applications.