Dr. B.P.S. Chauhan would like to gratefully acknowledge William Paterson University for assigned release time (ART) award for part of the research described here and also for the research program in general.

Note: All reagents are used as is from manufacturer with no further purification. Reactions were monitored for up to one week via UV-Vis spectroscopy to ensure complete reduction. All reactions are carried out under a vent hood and appropriate safety attire is worn at all times, including gloves, eye goggles, and lab coats.
1. Synthesis of Silver Nanoparticles
<ol>
	<li>Weigh out 0.0169 g (0.1 mmol) of silver nitrate directly into a 50 ml Erlenmeyer flask.</li>
	<li>Add in 20 ml of 18.2 M&#937; of ultrapure water and a magnetic stirrer bar. Cover flask with stopper to prevent evaporation.</li>
	<li>Place flask in an oil bath situated on a stirrer/hot plate and ensure that temperature is maintained at 60 &#176;C.</li>
	<li>Slowly add 144 &#181;l (0.2 mmol) of 2-AST using a precision micropipette. Flush pipette several times in solution to ensure all silane is transferred into the solution.</li>
	<li>Take UV-Vis spectroscopy readings according to protocol listed in Section 5.</li>
	<li>After 6 hr, remove sample from the oil bath and transfer to a 20 ml sample vial for storage, TEM, FTIR and further analysis. 
	Note: Synthesis of gold and palladium nanoparticles follows the same method and stoichiometric amounts with the exception of gold nanoparticles requiring 216 &#181;l (0.3 mmol) 2-AST. The reaction may continue to produce nanoparticles for up to 2 weeks, but the rate is not significant compared to initial rate.</li>
</ol>
2. Transmission Electron Microscope (TEM) Sample Preparation
<ol>
	<li>Ensure that sample has cooled to RT.</li>
	<li>Place a 200 carbon-mesh formvar-coated copper grid onto a clean piece of filter paper.</li>
	<li>Using a 1 ml plastic Pasteur pipette, cast-drop approximately 60 &#181;l of the nanoparticle sample directly onto the grid.</li>
	<li>Allow grid to dry for 24 hr before imaging.</li>
	<li>Take high-resolution TEM images with the following conditions: 10 &#181;A current and 100 kV accelerating voltage22.</li>
</ol>
3. Nuclear Magnetic Resonance (NMR) Sample Preparation
Note: Perform NMR at RT. At high temperatures signals may coalesce, which degrades the quality of spectra obtained.
<ol>
	<li>Using a precision pipette, pipette 50 &#181;l of deuterium dioxide (D2O) into a clean NMR tube.</li>
	<li>With another clean precision pipette, pipette 400 &#181;l of nanoparticle sample into the same NMR tube.
	<ol>
		<li>As samples may adhere to the inner walls of the NMR tube, slowly add solutions into the NMR tube. If sample does adhere, cap the tube and shake the top of the tube to force the solution to the bottom.</li>
	</ol>
	</li>
	<li>Mix the sample by shaking and repeatedly inverting the NMR tube.</li>
	<li>Place sample tube into the NMR following directions set by NMR protocol provided by manufacturer. An upwards of 1,000 scans may be necessary for proper resolution in a 1H proton NMR pulse program. 
	Note: NMR tube walls should be clean. It is recommended that the outer wall of the tube is wiped with a microfiber or lint free cloth prior to analysis for spectra clarity.</li>
	<li>Discard sample when finished. Do not return sample to parent solution.</li>
</ol>
4. Fourier Transform Infrared (FTIR) Spectroscopy Sample Preparation
<ol>
	<li>Place 2 ml of nanoparticle sample into a small glass container. A 3 ml tube or 1 dram glass vial works well.</li>
	<li>Dry the samples by placing the glass container in a vacuum desiccator fitted with a stopcock.</li>
	<li>Attach desiccator to vacuum pump apparatus. Drying of samples may take a few hours depending on vacuum strength. Consider samples dry after there is no visible liquid in container.</li>
	<li>Scrape down the sample using a clean spatula and collect solid materials.</li>
	<li>Place solid material onto ATR-FTIR spectroscope fitted with a ZnSe crystal diode laser.</li>
	<li>Obtain FTIR spectra integrating 32 scans between 4,000-500 cm-1 with a spectral resolution of 2.0. Use the air background23.</li>
</ol>
5. UV-Vis Spectroscopy Sample Preparation
<ol>
	<li>Conduct UV-Vis spectroscopy on nanoparticle samples that are in a one to ten dilution of nanoparticle sample to water so that saturation does not occur in spectrometer analysis.</li>
	<li>Remove nanoparticle samples for UV-Vis while reaction is running at half hour intervals.</li>
	<li>Using a precision pipette, remove 100 &#181;l of nanoparticle material and place into a plastic cuvette.</li>
	<li>Add 1 ml of ultrapure water to the same cuvette and mix thoroughly by flushing the pipette several times.</li>
	<li>Record UV-Vis absorbance spectrum between 250-800 nm.</li>
	<li>After analysis, do not return sample to reaction. Dispose of analyte in an appropriate manner.</li>
</ol>

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Rev. 40 (1), 233-245 (2011).</li><li>Richards, R., B&#246;nnemann, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+Approaches+to+Metallic+Nanomaterials.">Synthetic Approaches to Metallic Nanomaterials.</a> Nanofabrication towards Biomedical Applications. , 4-9 (2005).</li><li>Bradley, J., Schmid, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+6,+Unit+6.2.2,+The+Chemistry+of+Transition+Metal+Colloids:+Synthetic+Methods+for+the+Preparation+of+Colloidal+Transition+Metals.">Chapter 6, Unit 6.2.2, The Chemistry of Transition Metal Colloids: Synthetic Methods for the Preparation of Colloidal Transition Metals.</a> Clusters and Colloids. , 469-473 (1994).</li><li>Paterer, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigation+on+the+formation+of+copper+zinc+tin+sulphide+nanoparticles+from+metal+salts+and+dodecanethiol.">Investigation on the formation of copper zinc tin sulphide nanoparticles from metal salts and dodecanethiol.</a> Mater. Chem. Phys. 149-150, 94-98 (2015).</li><li>Yi, D. K., Lee, S. S., Ying, J. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Applications+of+Magnetic+Nanocomposite+Catalysts.">Synthesis and Applications of Magnetic Nanocomposite Catalysts.</a> Chem. Mater. 18, 2459-2461 (2006).</li><li>Piepenbrock, M. M., Lloyd, G. O., Clarke, N., Steed, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal-+and+Anion-Binding+Supramolecular+Gels.">Metal- and Anion-Binding Supramolecular Gels.</a> Chem. Rev. 110, 1960-2004 (2010).</li><li>Wu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+Structural+Characterization+of+Novel+Nanohybrids+by+Cationic+3D+Silica+Nanoparticles+Sandwiched+between+2D+Anionic+Montmorillonite+Clay+through+Electrostatic+Attraction.">Preparation and Structural Characterization of Novel Nanohybrids by Cationic 3D Silica Nanoparticles Sandwiched between 2D Anionic Montmorillonite Clay through Electrostatic Attraction.</a> J. Phys. Chem. C. 113 (30), 13036-13044 (2009).</li><li>Spitalsky, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+nanotube-polymer+composites:+Chemistry,+Processing,+Mechanical+and+Electrical+Properties.">Carbon nanotube-polymer composites: Chemistry, Processing, Mechanical and Electrical Properties.</a> Prog. Polym. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+silver+nanoparticles+by+microbial+method+and+their+characterization.">Synthesis of silver nanoparticles by microbial method and their characterization.</a> Arch. Phys. Res. 2 (3), 153-158 (2011).</li><li>Ghosh, S., Sarma, N., Mandal, M., Kundu, S., Esumi, K., Pal, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+gold+nanoparticles+in+micelle+by+UV-irradiation:+A+conductometric+study.">Evolution of gold nanoparticles in micelle by UV-irradiation: A conductometric study.</a> Curr. Sci. 84 (6), 791-795 (2003).</li><li>Paul, B., Bhuyan, B., Purkayastha, D. D., Dey, M., Dhar, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Green+synthesis+of+gold+nanoparticles+using+Pogestemon+benghalensis+(B)+O.+Ktz+leaf+extract+and+studies+of+their+photocatalytic+activity+in+degradation+of+methylene.">Green synthesis of gold nanoparticles using Pogestemon benghalensis (B) O. Ktz leaf extract and studies of their photocatalytic activity in degradation of methylene.</a> Mater. Lett. 148, 37-40 (2015).</li><li>Chauhan, B. P. S., Rathore, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regioselective+Synthesis+of+Multifunctional+Hybrid+Polysiloxanes+Achieved+by+Pt-Nanocluster+Catalysis.">Regioselective Synthesis of Multifunctional Hybrid Polysiloxanes Achieved by Pt-Nanocluster Catalysis.</a> J. Am. Chem. Soc. 127, 5790-5791 (2005).</li><li>Chauhan, B. P. S., Rathore, S., Bandoo, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#34;Polysiloxane-Pd&#34;+Nanocomposites+as+Recyclable+Chemoselective+Hydrogenation+Catalysts.">&#34;Polysiloxane-Pd&#34; Nanocomposites as Recyclable Chemoselective Hydrogenation Catalysts.</a> J. Am. Chem. Soc. 126, 8493-8500 (2004).</li><li>Chauhan, B. P. S., Rathore, S., Chauhan, M., Krawicz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+Polysiloxane+Stabilized+Palladium+Colloids+and+Evidence+of+Their+Participation+in+Silaesterification+Reactions.">Synthesis of Polysiloxane Stabilized Palladium Colloids and Evidence of Their Participation in Silaesterification Reactions.</a> J. Am. Chem. Soc. 125, 2876-2877 (2003).</li><li>Chauhan, B. P. S., Sardar, R., Tewari, P., Sharma, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> , 23-25 (2003).</li><li>Pouchert, C. J., Pouchert, C. .. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-Aromatic+Amines.">Non-Aromatic Amines.</a> The Aldrich Library of Infrared Spectra. , (1983).</li><li>Arkles, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared+Analysis+of+Organosilicon+Compounds:+Spectra-Structure+Correlations.">Infrared Analysis of Organosilicon Compounds: Spectra-Structure Correlations.</a> Silicon Compounds Register and Review. , (1987).</li><li>Corriu, R. J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypervalent+Species+of+Silicon-structure+and+Reactivity.">Hypervalent Species of Silicon-structure and Reactivity.</a> J. Organomet. Chem. 400, 81-106 (1990).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Basic Instruction Manual: Hitachi HT7700 TEM. , 1-28 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> OMNIC User's Guide Version 7.3: Thermo Electron Corporation. , 151-216 (2006).</li></ol>

There are no conflicting financial interests.

Salts reported in this paper are the only salts that were tested of that metal. As a result, it is uncertain that this reaction strategy would work with all salts of the metals, particularly gold. The solubility of these salts in water may also affect the outcome of the reaction in terms of reaction time, morphology, and yields. In all reactions, the silane was added to an already dissolved metal salt solution.
It is worth noting that care must be taken to ensure accuracy for these reactions require a small concentration of metal salts, which may be hygroscopic or deliquescent18. This issue was experienced in the gold chloride nanoparticle synthesis as gold complexes are air sensitive and may decompose when left exposed to air. In an effort to alleviate this, gold chloride salt was stored in a refrigerator until needed and then removed, quickly measured and returned to refrigeration when complete. Also, since a condenser is not used with the reaction vessel, care should be taken that the solvent does not evaporate during the heating phase. Water used as the solvent should be of high purity. Contaminates in solvent and pH variations may affect nanoparticle formation.
The production of gold and silver nanoparticles takes place under mild reaction conditions, which bodes well for this protocol in industrial applications. This method allows one to produce noble metal nanoparticles in aqueous medium with high yields. A major advantage of this method is that it does not require any additional reducing agent, which is known to complicate the isolation of resulting nanoparticles as additional purification steps may be needed. It is expected that this protocol will extend to other metals as well. This method can also provide an avenue where the particles can be rendered heterogeneous via sol gel methods.
Moreover, most of the materials can be converted to gels via copolymerization with other gelation agents21. Research is already underway to prepare and analyze such gels. Ongoing research is directed towards generating such a nanocomposite, which will be interesting for applications in recoverable heterogeneous catalysis.

As the demand and applications of designer nanomaterials increases, so do the various methods of synthesis. The &#34;top-down&#34; methods, such as laser ablation or chemical etching have been employed for their excellent controllability and capability of resolving materials reliably down to the sub-micron level. These methods rely on bulk materials being processed into finer components, which typically increase the cost of production as the desired nanostructure size decreases. An alternative method of synthesis to this is the &#34;bottom-up&#34; approach, which controls synthesis at the molecular level and builds up to the desired nanostructure. This imparts a significant degree of control on the desired self-assembly, functionality, passivity, and stability in the generation of these nanostructured materials1. By working from the molecular level, hybrid nanocomposites can be generated providing the benefits of both materials within the same structure.
As nanomaterials are synthesized through the bottom-up strategy, methods need to be employed to control particle size, shape, texture, hydrophobicity, porosity, charge, and functionality2. In metal core nanoparticle synthesis, the initial metal salt is reduced in an autocatalytic process to generate zero-valent particles, which in turn direct the nucleation of other particle. This leads to clustering and finally nanoparticle production3. In an effort to control the size of nanoparticles created and prevent them from precipitating out of solution, stabilizers such as ligands, surfactants, ionic charge, and large polymers are exploited for their ability to block nanoparticles from further agglomeration4-10. These materials inhibit the van der Waals attraction of the nanoparticles, either through steric hindrance due to the presence of bulky groups or through Coulombic repulsions3.
In this work, a facile, one pot, synthetic strategy for the generation of various metal core nanoparticles using the silane, n-(2-aminoethyl)-3-aminosilanetriol (2-AST) is presented (Figure 1). Ligands on this compound are capable of reducing metal precursors and stabilizing metal nanoparticles with a relatively high efficacy. The three silanol moieties present are also capable of crosslinking and this forms an interconnected network of organosilane polymer impregnated with nanoparticles within its matrix (Figure 2). Unlike most silanes, which readily undergo hydrolysis in the presence of water, this compound is stabilized in water, which is beneficial for hydrophobicity purposes, stability, and control.

<table><tbody><tr><td>n-(2-aminoethyl)-3-aminosilanetriol (2-AST)</td><td>Gelest</td><td>SIA0590.0</td><td>25% in H&lt;sub&gt;2&lt;/sub&gt;O</td></tr><tr><td>Silver nitrate</td><td>Sigma Aldrich</td><td>S6506</td><td></td></tr><tr><td>Gold(III) chloride trihydrate</td><td>Sigma Aldrich</td><td>520918</td><td></td></tr><tr><td>Palladium(II) Nitrate</td><td>Alfa Aesar</td><td>11035</td><td></td></tr><tr><td>Deuterium Dioxide</td><td>Cambridge Isotope Laboratories</td><td>DLM-4-100</td><td></td></tr></tbody></table>

generation of zerovalent metal core nanoparticles using n-(2-aminoethyl)-3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of n-(2-aminoethyl)-3-aminosilanetriol is presented. This compound can be used to effectively reduce and complex metal salts into metal core nanoparticles coated with the compound. By controlling the concentrations of salt and silane one is able to control reaction rates, particle size, and nanoparticle coating. The effects of these changes were characterized through transmission electron microscopy (TEM), UV-Vis spectrometry (UV-Vis), Nuclear Magnetic Resonance spectroscopy (NMR) and Fourier Transform Infrared spectroscopy (FTIR). A unique aspect to this reaction is that usually silanes hydrolyze and cross-link in water; however, in this system the silane is water-soluble and stable. It is known that silicon and amino moieties can form complexes with metal salts. The silicon is known to extend its coordination sphere to form penta- or hexa-coordinated species. Furthermore, the silanol group can undergo hydrolysis to form a Si-O-Si silica network, thereby transforming the metal nanoparticles into a functionalized nanocomposites.

The reaction was monitored via UV-Vis spectrometry as nanoparticle formation should produce peaks characteristic for each individual metal nanoparticle. The final analysis of synthesized materials was accomplished through TEM and FTIR. The FTIR spectra was obtained from dried powder of samples. The particle size analysis can be accomplished by measuring nanoparticle diameter from images obtained via TEM and averaging results.
Complexation of nanoparticles with 2-AST silane can be verified with FTIR by the presence of characteristic peaks for silane and amine functionalities (Figure 3C, 5C, &#38; 6C). Literature suggests the presence of Si-O-Si linkages can produce strong infrared absorption around 1,000 cm-1 with branching and extended polymer chains broadening this peak20. Peaks in the range of 1,550-1,650 cm-1 are attributed to NH2 deformation. A moderate NH2 stretch and NH wag can be seen at 3,000-2,750 cm-1 and 910-770 cm-1 respectively19.
For silver nanoparticle synthesis, the starting materials were added to a preheated solution and the reaction was monitored until reduction was complete. The UV-Vis spectroscopic analysis of the product showed the formation of silver nanoparticles with an increasing peak at approximately 414 nm (Figure 3A), which followed the literature values of the surface plasmon resonance of silver nanoparticles formation11, 12. The concentration of silver nanoparticles increased until the reduction of the metal salt was complete. After 6 hr of the reaction, TEM analysis (Figure 3B) confirmed the presence of silver nanoparticles. The particle size analysis showed that the majority of the nanoparticles were in the 10 &#177; 2.3 nm size range. In order to better understand the role of our silane compound, a RT&#160;1H NMR of the silver nanoparticle solution was conducted (Figure 4B). It is believed that the coordination of the amine to nanoparticles gives rise to the new peaks between 2.73 to 3.40 &#948;. Furthermore, the samples were re-analyzed again after one year and retained the same characteristics, verifying the stability of the particles.
The reaction with gold chloride was carried out in the same manner as the silver nitrate nanoparticle synthesis. In the gold samples, an increasing peak in the 533 nm range over the course of 6 hr (Figure 5A) was observed, which is characteristic of the surface plasmon resonance band for gold nanoparticles13, 14. The particle size analysis calculated the average size to be approximately 24 &#177; 5.4 nm in diameter (Figure 5B). A 1H NMR sample was prepared for the gold samples in the same manner as the silver (Figure 4C). The coordination of amines with the generated gold nanoparticles can be seen by the additional splitting peaks between 2.45-3.26 &#948;. These samples were also re-analyzed after one year and have been found to retain the same characteristics as the initial sample, which indicated that they too had good colloidal stability.
Palladium nanoparticles were synthesized in the same manner as the silver and gold reactions. It is well-known that a featureless spectra is obtained upon the production of Pd-nanoparticles; there is no observable &#955;max increase in UV-Vis spectrometry from surface plasmon resonance (Figure 6A) as Pd0 nanoparticles are produced15, 16, 17. However, TEM imaging and particle size analysis indicated that palladium nanoparticles, sized at 1.8 &#177; 0.56 nm in diameter (Figure 6B), were synthesized. A 1H NMR sample was prepared for this sample following the same preparative methods as the previous nanoparticles (Figure 4D). In the samples, the coordination of amines with Pd0 nanoparticles can be observed via the additional peaks between 2.81-3.26 &#948;.
<img alt="Figure 1" src="/files/ftp_upload/53507/53507fig1.jpg" /> 
Figure 1. Properties of n-(2-aminoethyl)-3-aminosilanetriol (2-AST). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53507/53507fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/53507/53507fig2.jpg" /> 
Figure 2. General scheme of the synthesis of 2-AST stabilized metal nanoparticles. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53507/53507fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/53507/53507fig3.jpg" /> 
Figure 3. Silver Nanoparticles. (A) UV-Vis spectral analysis of silver nanoparticle reaction mixture at a 1-10 dilution was monitored over time. (B) TEM imaging of silver nanoparticle. (C) FTIR of dried silver nanoparticle solution. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53507/53507fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" src="/files/ftp_upload/53507/53507fig4.jpg" /> 
Figure 4. NMR Spectrometry. 1H NMR of solution sample in D2O. (A) n-(2-aminoethyl)-3-aminosilanetriol; (B) silver nanoparticles; (C) gold nanoparticles; (D) palladium nanoparticles. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53507/53507fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" src="/files/ftp_upload/53507/53507fig5.jpg" /> 
Figure 5. Gold Nanoparticles. (A) UV-Vis spectral analysis of gold nanoparticle reaction mixture at a 1-10 dilution was monitored over time. (B) TEM imaging of gold nanoparticles. (C) FTIR of dried gold nanoparticle solution. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53507/53507fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" src="/files/ftp_upload/53507/53507fig6.jpg" /> 
Figure 6. Palladium Nanoparticles. (A) UV-Vis spectral analysis of palladium nanoparticle reaction mixture at a 1-10 dilution was monitored over time. (B) TEM imaging of palladium nanoparticles. (C) FTIR of dried palladium nanoparticle solution. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53507/53507fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol at JoVE.com

Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol

A novel method for metal core nanoparticle synthesis using a water stable silanol is described.

Generation of Zerovalent Metal Core Nanoparticles Using n-(2-aminoethyl)-3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of ...

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7.6K Views.  William Paterson University. A novel method for metal core nanoparticle synthesis using a water stable silanol is described.

Video: Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol

Using Polystyrene-block-poly(acrylic acid)-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are encapsulated in polystyrene-block-poly(acrylic acid) (PSPAA) shells and then used as monomers for their self-assembly. Spherical PSPAA micelles upon acid treatment are known to assemble into cylindrical micelles. Exploiting this tendency, the core-shell nanoparticles are induced to aggregate, coalesce, and then transform into long chains. When more than one type of nanoparticles are used, random and block &#8220;copolymers&#8221; of nanoparticles can be obtained. Detailed procedures are reported for the PSPAA encapsulation of nanoparticles, homo- and co-polymerization of the core-shell nanoparticles, separation and purification of the resulting nanoparticle chains. Transformations of single-line chains into double- and triple-line chains are also presented. The synergy between the polymer shell and the embedded nanoparticles leads to an unusual chain-growth polymerization mode, giving long nanoparticle chains that are distinct from the products of the traditional step-growth aggregation process.

Using Polystyrene-block-polyacrylic acid-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We report protocols for &#8220;polymerizing&#8221; various types of polymer-encapsulated metal nanoparticles into long chains of &#8220;homo-&#8220; and &#8220;co-polymers&#8221;.

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are ...

Reverse Microemulsion-mediated Synthesis of Monometallic and Bimetallic Early Transition Metal Carbide and Nitride Nanoparticles

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The silica-encapsulated metal oxide nanoparticles are then carburized in a methane/hydrogen atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal carbide nanoparticles. During the carburization process, the silica shells prevent the sintering of adjacent carbide nanoparticles while also preventing the deposition of excess surface carbon. Alternatively, the silica-encapsulated metal oxide nanoparticles can be nitridized in an ammonia atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal nitride nanoparticles. By adjusting the reverse microemulsion parameters, the thickness of the silica shells, and the carburization/nitridation conditions, the transition metal carbide or nitride nanoparticles can be tuned to various sizes, compositions, and crystal phases. After carburization or nitridation, the silica shells are then removed using either a room-temperature aqueous ammonium bifluoride solution or a 0.1 to 0.5 M NaOH solution at 40-60 &#176;C. While the silica shells are dissolving, a high surface area support, such as carbon black, can be added to these solutions to obtain supported early transition metal carbide or nitride nanoparticles. If no high surface area support is added, then the nanoparticles can be stored as a nanodispersion or centrifuged to obtain a nanopowder.

A &#8220;removable ceramic coating method&#8221; is presented in visual format for the synthesis of non-sintered and metal-terminated monometallic and bimetallic early transition metal carbide and nitride nanoparticles with tunable sizes and crystal structures.

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The ...

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

Synthesis of Bimetallic Pt/Sn-based Nanoparticles in Ionic Liquids

We demonstrate a method for the synthesis of bimetallic nanoparticles consisting of Pt and Sn. A synthesis strategy is used in which the particular physico-chemical properties of ionic liquids (ILs) are exploited to control both nucleation and growth processes. The nanoparticles form colloidal sols of very high colloidal stability in the IL, which is particularly interesting in view of their use as quasi-homogeneous catalysts. Procedures for both nanoparticle extraction in conventional solvents and for nanoparticle precipitation are presented. The size, structure and composition of the synthesized nanocrystals are confirmed using inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX). By this, we show that the nanocrystals are random-type alloy and of small (2-3 nm) size. The catalytic activity and selectivity in the hydrogenation of &#945;,&#946;-unsaturated aldehydes is tested in a semi-continuous batch-type reactor. In this context, the bimetallic Pt/Sn-based nanoparticles reveal a high selectivity towards the unsaturated alcohol.

A protocol for the synthesis of bimetallic nanoparticles in ionic liquids and the procedure of their catalytic testing in the selective hydrogenation of unsaturated aldehydes are described.

We demonstrate a method for the synthesis of bimetallic nanoparticles consisting of Pt and Sn. A synthesis strategy is used in which the particular ...

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, &#60;10-5 mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 &#176;C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. 1H and 13C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei (15N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol&#183;g-1) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [(&#8801;Si-O-)Hf(&#951;2&#960;-MeNCH2)(&#951;1-NMe2)(&#951;1-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)]. [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is correlated to the catalytic performance.

A new group IV metal catalyst for imine metathesis is prepared by grafting amine metal complex onto dehydroxylated silica. Surface metal fragments are characterized using FT-IR, elemental microanalysis, and solid-state NMR spectroscopy. Further dynamic nuclear polarization surface enhanced NMR spectroscopy experiments complement the determination of the coordination sphere.

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared ...

Preparation of Silver-Palladium Alloyed Nanoparticles for Plasmonic Catalysis under Visible-Light Illumination

Localized surface plasmon resonance (LSPR) in plasmonic nanoparticles (NPs) can accelerate and control the selectivity of a variety of molecular transformations. This opens possibilities for the use of visible or near-IR light as a sustainable input to drive and control reactions when plasmonic nanoparticles supporting LSPR excitation in these ranges are employed as catalysts. Unfortunately, this is not the case for several catalytic metals such as palladium (Pd). One strategy to overcome this limitation is to employ bimetallic NPs containing plasmonic and catalytic metals. In this case, the LSPR excitation in the plasmonic metal can contribute to accelerate and control transformations driven by the catalytic component. The method reported herein focuses on the synthesis of bimetallic silver-palladium (Ag-Pd) NPs supported on ZrO2 (Ag-Pd/ZrO2) that acts as a plasmonic-catalytic system. The NPs were prepared by co-impregnation of corresponding metal precursors on the ZrO2 support followed by simultaneous reduction leading to the formation of bimetallic NPs directly on the ZrO2 support. The Ag-Pd/ZrO2 NPs were then used as plasmonic catalysts for the reduction of nitrobenzene under 425 nm illumination by LED lamps. Using gas chromatography (GC), the conversion and selectivity of the reduction reaction under the dark and light irradiation conditions can be monitored, demonstrating the enhanced catalytic performance and control over selectivity under LSPR excitation after alloying non-plasmonic Pd with plasmonic metal Ag. This technique can be adapted to a wide range of molecular transformations and NPs compositions, making it useful for the characterization of the plasmonic catalytic activity of different types of catalysis in terms of conversion and selectivity.

Presented here is a protocol for the synthesis of silver-palladium (Ag-Pd) alloy nanoparticles (NPs) supported on ZrO2 (Ag-Pd/ZrO2). This system allows for harvesting energy from visible light irradiation to accelerate and control molecular transformations. This is illustrated by nitrobenzene reduction under light irradiation catalyzed by Ag-Pd/ZrO2 NPs.

Localized surface plasmon resonance (LSPR) in plasmonic nanoparticles (NPs) can accelerate and control the selectivity of a variety of molecular ...

Gold Nanoparticle Synthesis

Gold nanoparticles (Au nanoparticles) that are ~12 nm in diameter were synthesized by rapidly injecting a solution of 150 mg (0.15 mmol) of tetrachloroauric acid in 3.0 g (3.7 mmol, 3.6 mL) of oleylamine (technical grade) and 3.0 mL of toluene into a boiling solution of 5.1 g (6.4 mmol, 8.7 mL) of oleylamine in 147 mL of toluene. While boiling and mixing the reaction solution for 2 hours, the color of the reaction mixture changed from clear, to light yellow, to light pink, and then slowly to dark red. The heat was then turned off, and the solution was allowed to gradually cool down to room temperature for 1 hour. The gold nanoparticles were then collected and separated from the solution using a centrifuge and washed three times; by vortexing and dispersing the gold nanoparticles in 10 mL portions of toluene, and then precipitating the gold nanoparticles by adding 40 mL portions of methanol and spinning them in a centrifuge. The solution was then decanted to remove any remaining byproducts and unreacted starting materials. Drying the gold nanoparticles in a vacuum environment produced a solid black pellet; which could be stored for long periods of time (up to one year) for later use, and then redissolved in organic solvents such as toluene.

A protocol for synthesizing ~12 nm diameter gold nanoparticles (Au nanoparticles) in an organic solvent is presented. The gold nanoparticles are capped with oleylamine ligands to prevent agglomeration. The gold nanoparticles are soluble in organic solvents such as toluene.

Gold nanoparticles (Au nanoparticles) that are ~12 nm in diameter were synthesized by rapidly injecting a solution of 150 mg (0.15 mmol) of ...

Triplet Fusion Upconversion Nanocapsule Synthesis

Triplet fusion upconversion (UC) allows for the generation of one high energy photon from two low energy input photons. This well-studied process has significant implications for producing high energy light beyond a material's surface. However, the deployment of UC materials has been stymied due to poor material solubility, high concentration requirements, and oxygen sensitivity, ultimately resulting in reduced light output. Toward this end, nanoencapsulation has been a popular motif to circumvent these challenges, but durability has remained elusive in organic solvents. Recently, a nanoencapsulation technique was engineered to tackle each of these challenges, whereupon an oleic acid nanodroplet containing upconversion materials was encapsulated with a silica shell. Ultimately, these nanocapsules (NCs) were durable enough to enable triplet fusion upconversion-facilitated volumetric three-dimensional (3D) printing. By encapsulating upconversion materials with silica and dispersing them in a 3D printing resin, photopatterning beyond the surface of the printing vat was made possible. Here, video protocols for the synthesis of upconversion NCs are presented for both small-scale and large-scale batches. The outlined protocols serve as a starting point for adapting this encapsulation scheme to multiple upconversion schemes for use in volumetric 3D printing applications.

This protocol details the synthesis of upconversion nanocapsules for subsequent use in photopolymerizable resins for triplet fusion upconversion-facilitated volumetric 3D printing.

Triplet fusion upconversion (UC) allows for the generation of one high energy photon from two low energy input photons. This well-studied process has ...

Generation of Zerovalent Metal Core Nanoparticles Using n-(2-aminoethyl)-3-aminosilanetriol

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