Dissertations / Theses on the topic 'GREEN SYNTHESIS METHOD'

Cancer is the second most frequent cause of death in the world today and a huge global problem for the society. Current drug delivery systems used in the treatment of cancer suffer from a number of problematic issues, like poor plasma half-life and poor release profile of therapeutic agents. To overcome these limitations, recent research has focused on using calcium carbonate(CaCO3) micro/nanoparticles as carrier-based systems to improve drug therapies and clinical outcomes. The present study investigates and evaluates a newly developed Reverse Micelle method for generating micro/nanometre scale CaCO3 powders for potential use as a drug carrier platform. XRD spectroscopy revealed the CaCO3 was in the form of calcite and it had a mean crystallite size of 9.3nm. However, the study found the Reverse Micelle method had a preference to produce larger micrometre scale particles instead of only nanometre scale particles. Both SEM and particle analysis revealed 45.46% of the particles were between 8 and 16μm and the mean particle size was 10μm.The resulting calcite ultra-powders were found to have a relatively low specific surface area of around 0.577 m2 g−1 and also found to display poor adsorption behaviour towards Rhodamine B. To explain this behaviour, the study suggests water present in the washing and centrifuging stage promotes the dissolution and re-crystallisation, thus, promoting further growth of the calcite particles. In addition, the FT-IR analysis suggests surfactant residue, persistent even after extensive washing, is responsible for the poor adsorption behaviour of the calcite powders. However, in spite of the shortcomings, the present research has established the Proof of Concept for the innovative Reverse Micelle method. And the results from the research were used to apply for an Australian Innovation Patent, which was subsequently granted. Thus, validating the Proof of Concept and the quality of the research carried out as part of the present work.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology<br>The present study includes the use of a green synthetic method to prepare copper and silver nanoparticles using chitosan, aqueous extracts of Camellia sinensis, Combretum molle and Melia azedarach linn leaves. This study aims to investigate the influence of capping and precursor concentration on the properties of silver nanoparticles with emphasis on the medicinal plants chosen. The effect of capping agent on the properties of copper nanoparticles is also investigated. The phytochemical properties of plant extracts and the antimicrobial activity of the synthesized particles were also studied; this was achieved by using microdilution bioassay. Decoction method was used to extract secondary metabolites from plant leaves. Preliminary phytochemical screening carried out on the aqueous extracts of the plant leaves showed the presence of tannins, proteins, flavonoids, phenols, and carbohydrates. The total phenolic and flavonoids content of the aqueous extract was determined using spectroscopic methods. The highest phenolic content was found in the aqueous extract of Combretum molle (135 mg/g), and the highest flavonoid content was found in the aqueous extract of Camellia sinensis (0.4 mg/g). Characterization was done by a combination of spectroscopic, microscopy and XRD techniques. Both the size and shape of the synthesized silver nanoparticles were dependent on the identity of the capping molecule, precursor and capping agent concentration as depicted from their TEM and XRD results. Silver nanoparticles were found to be predominantly spherical. The capping agent concentration was also found to influence the degree of agglomeration, with an increase in capping agent concentration giving lesser agglomeration. FTIR spectral analysis showed that silver nanoparticles interact with bioactive compounds found in the plants through the hydroxyl functional group. Other shapes including diamond were observed for the effect of precursor concentration. The XRD micrographs revealed a face-centered cubic geometry and the phase remained the same with an increase in precursor concentration. The synthesized silver nanoparticles were all blue shifted compared to the bulk material. The TEM results revealed that copper nanoparticles with different sizes and shapes were successfully synthesized. All the prepared copper and silver nanoparticles showed satisfactory antifungal and antibacterial activity against Candida albicans, Cryptococcus neoformans, Staphylococcus aureus, Enterococcus faecalis, Klebsiella pneumonia and Pseudomonas aeruginosa. The capping molecules used in this study also showed some antibacterial and antifungal activity against the selected strains. However nanoparticles performed better than these capping molecules. Both silver and copper nanoparticles were found to be more active against gram-negative bacteria compared to gram-positive bacteria. Amongst all the prepared silver nanoparticles Combretum molle capped nanoparticles were found to be the most active nanoparticles. Also with copper nanoparticles, it was found that Combretum molle capped nanoparticles were the most active nanoparticles. Between the two metal nanoparticles, silver nanoparticles showed high antibacterial and antifungal activity compared to copper nanoparticles. The antioxidant activity of silver nanoparticles was assessed using 2.2-diphenyl-1-picrylhydrazyl. Silver nanoparticles were found to have some antioxidant activity. However, the capping molecules were found to be more active than the synthesized nanoparticles. This observation is attributed to the presence of some bioactive compounds in the plant extracts.

Metal nano particles are one of the most attractive aspects of nano materials in recent years. The reason for this growing attraction is because of their special physical and chemical properties, which are more enhanced from bulk material. Hence they find wide application in various fields like catalysis, photonics, optoelectronics, information storage, antibacterial applications, etc. While considering metal nano particles, electrical conductivity is one of the most important properties that can be used for humans’ benefit and should be enhanced. Silver nano particles can be used in the electronics industry as conductive fillers because of their unique properties such as high electrical and thermal conductivity, high resistance to oxidation. It is impressive that eco friendly methods are being developed for synthesizing these nano particles, using different kinds of plant extracts and water soluble component as capping agents, which results in different forms of particle morphologies. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35238

The synthesis of gold nanoparticles by one of the many popular microorganisms – blue-green algae Spirulina platensis was studied. The complex of optical and analytical methods was applied for investigation of experimental samples after exposure to chloroaurate (HAuCl4) solution at different doses and for different time intervals. To characterize formed gold nanoparticles UV-vis Spectrometry, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy-dispersive analysis of X-rays (EDAX) were used. It was shown that after 1.5 – 2 days of exposure the extracellular formation of nanoparticles of spherical form and the distribution peak within the interval of 20-30 nm took place. To determine gold concentrations in the Spirulina platensis biomass neutron activation analysis (NAA) was applied. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34969

Magister Scientiae - MSc (Physics)<br>Zinc oxide (ZnO) is a wide and direct semiconductor with a wurtzite crystal structure. Its multifunctionality as the ideal candidate in applications such as blue-UV light emitting diodes, transparent conducting oxide, selective gas sensor and efficient catalyst support among others, has attracted a significant interest worldwide. Nano-scaled ZnO has been synthesized in a plethora of shapes. A rich variety of physical and chemical methodologies have been used in the synthesis of undoped or doped ZnO. However, such methods either necessitate relatively high vacuum infrastructures, elevated temperatures, or the use of toxic reagents. The "green chemistry" synthesis of metal oxide nanoparticles which is based on using natural plant extract as an effective 'reducing agent' of metal precursor, has been reported to be a cleaner and environment-friendly alternative to the physical and chemical methods. The thesis is based on the synthesis and the main physical properties of pure ZnO nanoparticles synthesized by a completely green chemistry process using the natural extract of Aspalathus Linearis to bio-reduce the zinc acetate precursor. The obtained ZnO nanopowdered samples were annealed at different temperatures from 300 °C to 600 °C. The samples were characterized using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Transmission Electron Microscopy, X-ray Diffraction, Differential Scanning Calorimetry, Thermogravimetric Analysis and Fourier Transform Infrared. Highly pure quasi-spherical ZnO nanoparticles with an average crystallite size of 24.6 nm (at 300 °C), 27.2 nm (at 400 °C), 27.6 nm (at 500 °C), and 28.5 nm (at 600 °C) were found. The results also showed that the average crystallite size increased with an increase in annealing temperature. It was successfully demonstrated that the natural plant extract of Aspalathus Linearis can be used in the bio-reduction of zinc acetate dihydrate to prepare highly pure ZnO nanoparticles.

碩士<br>國立嘉義大學<br>應用化學系研究所<br>106<br>In this study, we used bovine serum albumin (BSA) both as the capping agent and reducing agent to synthesize polyhedral gold nano- particles in aqueous solutions based on a simple one-pot strategy. The method used was in compliance with the green chemistry principles. The syntheses of gold nanoparticles were influenced by metal ions. To synthesize polyhedral gold nanoparticles, metal ions were added to the mixtures of BSA and chloroauric acid (HAuCl4). The resulting polyhedral gold nanoparticles included triangular plates, hexagonal plates, spherical particles, octahedrons, decahedrons, and icosahedrons. Among the metal ions screened, copper (Ⅱ) ion and iron (Ⅲ) ion had significant effects on both the morphology and growing rate of gold nanoparticles. Thus, the influences of several factors that affected the synthesis of polyhedral gold nanoparticles in the presence of copper (Ⅱ) and iron (Ⅲ) ions were investigated. The factors studied included the BSA concentration, metal ion concentration, temperature, reaction time, pH of solution, and amount of various diols added. The proceedings of synthesis were monitored based on the UV-Vis spectra of the reaction mixtures. The shapes and size of gold nano- particles synthesized were confirmed with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). When the molar ratio of Cu2+ and HAuCl4 was 1 to 8.33, icosahedral gold nanoparticles were the major product at 60 ℃. In this reaction condition, the average yield was 50.92 %, and the average size of nanoparticle was 141.86 ± 12.16 nm. In addition, flower-shaped gold nanoparticles was synthesized by refluxing the reaction mixture in the presence of 1, 5-pentane and Fe3+. The average diameters of the resulting gold nano- particles were 139.49 ± 15.07 nm. Since the polyhedral gold nano- particles synthesized were highly uniform and the toxicity of the capping agent used was low, this one-pot strategy had the great potential to synthesize the polyhedral gold nanoparticles with high biocompatibility which can then be used in biomedicine and bioanalysis.

博士<br>國立臺北科技大學<br>電機工程系<br>107<br>In the past, the preparation of metal nanoparticles has been carried out by a chemical method, and a suspension agent is added to control the particle size and concentration of the nanoparticles. In this dissertation, an electric discharge machine (EDM) or a Micro EDM is used to melt metal materials into nanometer-scale particles by arc discharge. No chemical is added during the manufacturing process, and pure water is used as the medium. Electro-hydraulic, set process parameters and discharge pulse width time (TON-TOFF), can prepare nano-grade metal particles suspended in dielectric liquid, the process is simple and fast, can be mass-produced, low cost, environmental pollution Smaller, this method contributes greatly to the preparation of nanomaterials. In this dissertation, the study of nano-small is carried out by using pulsed spark discharge (Pulsed Spark Discharge) method to prepare nano-Bi colloidal solution in deionized water (DI-water) by adjusting the TON, TOFF and discharge current IP of the EDM. The value causes the Bismuth wire to generate a pulsed spark discharge in deionized water to prepare a nano-Bi colloidal solution, then the Transmission Electron Microscope(TEM), Energy-dispersive X-ray spectroscopy(EDX), Zetasizer, Ultraviolet–Visible Spectroscopy (UV-Vis) and other instruments were used to analyze the results of the nano-Bi colloidal prepared under different discharge parameters, so as to obtain the optimized parameters of the preparation of nano-Bi by pulse spark discharge machine. The results of this dissertation show that the nano-Bismuth colloidal solution was successfully prepared by EDM and the absorption peak of UV–Vis was found at 234~237 nm. In addition, in order to find out the Proportional Integral Derivative (PID) control parameter while using the Micro EDM to prepare the Bismuth colloid, the mathematical model of Micro EDM was successfully derived, the PID parameters were found by Matlab software-assisted analysis and put them into the Micro EDM for experiment, compared with the discharge success rate of the online adaptation method (36%), and the Ziegler-Nichols (ZN) method. (36.451%), the discharge success rate of preparing nano silver was increased to 84.4773%, and the discharge success rate of preparing nano-Bismuth colloid solution can reach 74.1876%.

Terbium doped hydroxyapatite (THA), Tb:Ca10(PO4)6(OH)2 phosphors synthesized via surfactant (CTAB) assisted aqueous precipitation method. It is basically a room temperature synthesis excluding the sintering at 550o C, which was performed just for the removal of residual organic template. The phase, morphology, luminescent properties of THA powders were examined by usingX-ray diffraction, scanning electron microscopy (SEM), excitation and emission spectra. XRD analysis reveals the nanocrystalline nature of THA with crystallite size 48 nm. SEM images indicate the formationof ‘micro-cubes’ with uniform size distribution. Excitation spectra measured for THA samples by monitoring 541nm emission wavelength. Emission spectra measured for the THA samples by exciting the samples at 377 nm wavelength.The intensities of the emission peaks were found to be increasing with the increase ofterbium concentration. The Commission Internationale deI’Eclairage (CIE) chromaticity coordinates calculated for the synthesized THA phosphor, which indicate thatthe terbium doped hydroxyapatitephosphor exhibits yellowish green emission under 377 nm excitation.

There are several possible uses of silver nanoparticles (AgNPs) in energy storage systems, antimicrobial sensors, and other biological sensors. Silver nanoparticles were synthesized using extract obtained from leaves of Azadirachta Indica (Neem), Ocimum Tenuiflorum (Tulsi), and Mentha (Mint). Thin films of various samples were then prepared using drop-cast method. In order to study their structural properties, they are then characterized with different analytic techniques like X-ray diffractometer (XRD) and ultraviolet visible Spectroscopy. To compare the particle size of NPs obtained from different plant leaves, XRD characterization was done. XRD patterns ratifies synthesis of silver nanoparticles in single crystalline phase and confirms the FCC structure with a particles size of 13.58 nm (obtained from neem extract). UV-Visible absorption spectrum for different samples neem, tulsi and mint were recorded in the wavelength ranges of (270-600) nm.

Green synthesis of nanoparticle is a novel way to synthesis nanoparticles by using biological sources. It is gaining attention due to its cost effective, ecofriendly and large scale production possibilities. In this present study five plants Hibiscus rosa sinensis, Cucurbita maxima, Moringa oleifera, Azadirachta indica and Acorus calamus were taken to investigate their potential for synthesizing silver nanoparticle. The silver nanoparticles synthesized were confirmed by their change of colour to dark brown due to the phenomenon of surface plasmon resonance. The characterization studied was done by UV-vis spectroscopy, Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Dynamic light scattering (DLS) and zeta potential studies, X-Ray diffraction (XRD), Fourier Transmission infrared spectroscopy (FTIR). All the five plants synthesized silver nanoparticle show good antimicrobial activity against clinically important pathogens Staphylococcus aureus, Klebsiella pneumoniae, Vibrio cholera and Escherichia coli.

博士<br>國立東華大學<br>化學系<br>99<br>We have demonstrated the synthesis of simple Kegan’s ether I.45. The attempt of synthesizing complex Kegan’s ether analogue I.51 was failed. In order to synthesize pinene based molecular tweezer, we have tried a number of methods but unfortunately none of them succeed to the desired product. Alternately the route adopted for the synthesis of molecular tweezer ended up with the product tetrahydro-7-oxa-benzocyclohepten-6-ol (I.84). In the synthesis of Tröger’s base derived BINOL-mimics by Suzuki cross-coupling methodology, coupling of simple phenol moiety to the Tröger’s base furnished inseparable mixture of rotamers I.93. However in order to restrict rotation, efforts taken for coupling bulky naphthol moiety were failed. We have presented a simple route to the BINOL based Tröger’s bases, where mixture of diastereomers (I.101a and I.101b) were identified by extensive 1D, 2D NMR and X-ray studies. Unfortunately we were unable to illustrate the structure of BINOL-TB-2 but conclusions based on the 1H NMR and 13C NMR, established the fact about non-symmetrical nature of the compound. The first RCM driven isomer-divergent stereocontrolled synthesis of both isomers of pericosine family (+)-Pericosine A and B from an easily available carbohydrate based acyclic precursor with 35% and 41% overall yields; respectively, have been established. Our method provides a simple means to these chirality-rich targets without unnecessary dragging of synthetic steps. We feel the well-knotted use of NHK vinylation and RCM in our effort should find application in simplifying problems in many related synthesis in future. We have presented elegant routes to (±)-MMDA-d3 and zaleplon-d5, as internal standards. This synthesis provides an option for the quantitative detection of (±)-MMDA and zaleplon in drug abusers. The metal nitrates, TNCB, TBAP and HMTAI are valuable addition to the methods currently available for the oxidation of Hantzsch’s 1,4-DHPs. A short reaction time, easy work-up and good to excellent yields of corresponding pyridines are obtained. Additionally, this protocol provides transformation to corresponding pyridines without any external activation such as microwave or ultrasound. Nifedipine-d3 (III.7) is easily and elegantly synthesized and ultimately converted to the corresponding dehydronifedipine-d3 (III.8), which can be exploited as an internal standard for the quantitative measurement of the consumption of nifedipine in the body. This synthesis may be useful in studying metabolic activity and pharmacokinetics and in the quantitative analysis of nifedipine. The electrophilic substitution reactions of indole with aromatic, heteroaromatic and aliphatic carbonyl compounds were successfully carried out in the presence of a catalytic amount of AgBF4 in dichloromethane at reflux temperature. This method offers several significant advantages over common methods, such as high conversion rates, ease of handling, and clean reaction profiles, which make it attractive for the rapid synthesis of substituted bisindolylmethanes. The present approach was proved to be suitable for the synthesis of complex systems, such as tetraindolylmethane Troger’s Base III.42. We have described an easy synthesis of a new class of pineno-salen type of ligands in good to excellent yields and utilized for enantioselective NHK reaction. After been synthesized several non-C2-symmetric pineno-salen type ligands and under optimized condition, ligand III.27a proved to be the best, promoting good levels of stereoinduction. A number of unique and important features, including pronounced chemoselectivity of this protocol and unprecedented compatibility with numerous functional groups over substituted aromatic, heteroaromatic and aliphatic aldehydes have led to the reaction being more attractive. We believe that NHK reaction using catalytic amounts of chromium salt, which is, the all time low quantity quoted elsewhere, in combination with the cheap and nontoxic manganese as a suitable stoichiometric reductant has taken a leap forward towards practicing environmentally benign green chemistry. Notably, this is the first precedent reporting lowest amount of catalyst loading (5 mol %) for effective and efficient enantioselective NHK reaction of aldehydes stating the unique feature of this protocol. We have studied the scope of rapid and efficient methods for the selective deprotection of MOM ethers and presented novel, mild and green protocol for the deprotection of both alcoholic and phenolic MOM ethers. This protocol removed MOM from a variety of MOM ethers of primary, secondary and phenol derivatives. Most of the reactions were complete within short reaction, with both high yield and selectivity in the presence of other protecting groups such as, acetyl or benzyl group. Additionally, the study also demonstrated that acid sensitive groups on sugar is unaffected by the present reagent system, especially taken in to account of their vulnerability towards acidic condition. This rapid and efficient method for selective deprotection of MOM ethers could open a new horizon for MOM groups in hydroxyl protection.

碩士<br>中原大學<br>化學研究所<br>107<br>The primary concern of this study is developing novel synthetic methods to synthesize compounds with bioactive frameworks based on green chemistry principles. First, we developed a direct vinylogous aldol reaction of 3-alkylidene oxindoles with isatins using molecular sieve. We constructed the products with 3,3-disubstituted oxindoles frameworks successfully in high yields (up to 98% yield). Next, we also developed a decarboxylative 1,6-conjugate addition reaction of β-keto acids and p-quinone methides. We only used fluorinated alcohols as solvent without bases and catalysts to construct the products with diarylmethanes frameworks successfully in high yields (up to 99% yield).