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Novel Inorganic and Metal Nanoparticles Prepared by Inverse Microemulsion
Published in Victor M. Starov, Nanoscience, 2010
The challenge has been and remains the control of the size, the size distribution, and the shape of NPs. The electrical, optical, and magnetic properties vary widely with these parameters. There is a wide variety of techniques producing NPs. They essentially fall into three categories: condensation from a vapor, chemical synthesis, and solid-state processes [5,6]. Other novel production techniques have been reported based on the use of microwaves, ultrasound, and biomimetics. Biological processes are very interesting because of the ability of natural systems to create almost atomically perfect nanostructures. Some bacteria create magnetic and silver NPs, and bacterial proteins have been used to grow magnetite. Yeast cells can create cadmium sulfide NPs. A fungus was observed to be capable of making gold NPs, and viral proteins can create silver NPs with interesting and well-formed shapes [7]. Doughnut-shaped nanoreactors (peptide nanodoughnuts reactors) were used to prepare monodisperse gold nanocrystals [8]. The nanodoughnuts were self-assembled from peptides and organic gold salts. To synthesize nanomaterials in controlled sizes and dimensions, various types of nanoreactors, nanometer-sized chemical reaction vessels, have been developed [9,10]. Because these nanoreactors are removed by means of external stimuli to extract products after nanomaterials are synthesized, the nanoreactors are applied not only in material syntheses but also in controlled release and drug delivery.
Photonics of Nanostructured Biomineral Objects and Their Biomimetic Analogues
Published in Yu. N. Kulchin, Modern Optics and Photonics of Nano and Microsystems, 2018
Some organic templates can be used as nanoreactors for the synthesis of inorganic nanoparticles. For example, in the thermal reduction of [AuCl4] $ [{\text{AuCl}}_{4} ] $ in a siloxane‐acrylate microemulsion solution, which is a hydrophobic core with a hydrophilic shell, emulsion particles can be obtained in which gold nanoparticles are immobilized (Fig. 20).
Principles of Green Chemistry
Published in Sanjay K. Sharma, Hasan Demir, Green Chemistry in Scientific Literature, 2019
The Suzuki cross-coupling reaction has fewer limitations and is environmentally friendly, efficient, and highly useful for the drug industry, compared to Heck reaction, Kumada, Stille, Negishi, and Sonogashiri coupling reactions (Franzén and Xu 2005). The Mannich reaction leads to the production of amino carbonyl compounds, and 1,2-amino alcohol derivatives have been satisfactorily achieved in water (Iwanejko, Wojaczyńska, and Olszewski 2018). Friedel-Crafts alkylation has also another greener process with new approaches that gained the attention of researchers in recent years. The new approach in Friedel-Crafts alkylation reaction allows using a low amount of catalyst. Additionally, benzyl-, propargyl- and allyl alcohols, or styrenes are started to be used instead of toxic benzyl halides (Rueping and Nachtsheim 2010). Catalytic nanoreactors provide operation of organic reactions in aqueous medium, reducing environmental risks for obtaining chemical sustainability. De Martino et al., (2018) reviewed E-factors of traditional and nanoreactor catalytic reactions in the pharmaceutical industry as shown in Figure 3.10. E-factors of reactions in the pharmaceutical industry decreased significantly using micellar nanoreactors. The advantages of nanoreactors, which are polymersomes, micelles, dendrimers, and nanogels, can be explained as: Promotion of cascade reactions Generation of hydrophobic materials in aqueous and greener conditions Easy recovery of catalyst (De Martino et al. 2018)
Intensity-dependent optical nonlinearities of composite materials made of ionic liquid crystal glass and bimetallic nanoparticles
Published in Liquid Crystals, 2023
V. Rudenko, A. Tolochko, D. Zhulai, S. Bugaychuk, G. Klimusheva, G. Yaremchuk, T. Mirnaya, Yuriy Garbovskiy
Mesogenic metal alkanoates are excellent glass forming materials. In addition, they can be used as nanoreactors for template synthesis of nanoparticles. By vitrifying liquid crystals containing nanoparticles, nonlinear-optical glass nanocomposites can be obtained. In this paper, by applying the aforementioned approach, we produced liquid crystal glass made of cadmium octanoate and containing bimetallic Ag/Au nanoparticles of two types (homogeneous Ag/Au alloy and Ag/Au core – Au shell). The studied samples exhibit a strong nonlinear-optical response (10−7 - 10−8 esu, Table 2–3) suitable for photonics applications relying on third-order optical nonlinearities [8]. Both nonlinear absorption coefficients and nonlinear refractive indices of the studied materials are intensity-dependent (Figures 2–5, Tables 2–3). This dependence on intensity is caused by several physical factors. Intensity-dependent nonlinear absorption coefficients (Figures 2 and 4, Table 2, 3) originate from the competition between saturable absorption, two-photon absorption, and nonlinear-optical light scattering processes. The dependence of nonlinear refractive indices on the intensity of light (Figures 3 and 5, Table 2, 3) is a consequence of several nonlinear-optical mechanisms (local field factor due to the cadmium octanoate, intrinsic nonlinearity of bimetallic nanoparticles, thermal effects) acting simultaneously. Table 2, 3 also suggest that by changing the type of bimetallic nanoparticles, both negative and positive nonlinear-refractive indices of nanocomposites can be achieved.
Core shell particles
Published in Surface Engineering, 2022
Lakshmi Gopal, Tirumalai Sudarshan
Hollow nanostructures, which are essentially core-shell particles in which the shell encapsulates an empty or partially filled space, are also of significant academic interest because the presence of the cavities results in the reduction of the density compared to the dense solid counterparts for equal volumes of materials'. Hollow nanoparticles with empty or partially filled cores (Figure 7) have been studied for use as catalytic hollow nanoreactor systems with high activity, selectivity, and recyclability. The shells are usually permeable, and allow only specific substrate molecules to access the interior cavity that houses the catalytic site, thereby enabling substrate-selective catalysis. Such nanoreactor cores are usually made of noble metals and their alloys, or magnetic/transition metal oxides, and the shells are made of ceramic oxide materials or carbon-based materials, such as amorphous carbon and reduced graphene oxide, and organic polymers [19].
A synergetic effect of sonication with yolk-shell nanocatalyst for green synthesis of spirooxindoles
Published in Green Chemistry Letters and Reviews, 2021
Somaye Mohammadi, Hossein Naeimi
The mesoporous silica spheres with magnetic metal nanoparticles (such as Fe2O3) to shape yolk–shell nanostructures has attracted opinion for the chemist in recently years (1, 2). These compounds have a very high active surface for used in different sciences. This nanostructure has potential for use as the nanocatalyst (3–5), nanoreactors (6, 7) and drug delivery compounds (8). The method for preparation of yolk–shell nanostructure was used template-assisted that contained a synthesis of core materials that coated with two shells (9–11). In the end, was removed the middle shell with chemical or hydrothermal methods. However, the yolk–shell nanostructure has high active catalytic surface and low density (12, 13) so it can to use for two functional system at the core and shell at the same time (14–16).