Name: the effect of ultraviolet radiation on the chemical bath deposition of bis(thiourea) cadmium chloride crystals and the subsequent cds obtention
Uploaded: 2018-08-30T14:00:00
Description: Watch this Scientific Journal Video about The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bisthiourea Cadmium Chloride Crystals and the Subsequent CdS Obtention at JoVE.com

L.E. Trujillo and F.J. Willars Rodr&#237;guez thank CONACYT for their scholarships. E.A. Chavez-Urbiola thanks CONACYT for the &#34;Catedras CONACYT&#34; program. Authors also acknowledge the technical assistance of C.A. Avila Herrera, M. A. Hern&#225;ndez Landaverde, J.E. Urbina Alv&#225;rez, and A. Jim&#233;nez Nieto.

CAUTION: The chemicals used in this protocol are toxic and carcinogenic; thus, the safety recommendations and procedures must be followed carefully. Wear proper protective equipment and consult any relevant materials safety data sheet (MSDS).
1. Synthesis of Bis(thiourea) Cadmium Chloride
<ol>
	<li>Preparation of the precursor solution
	<ol>
		<li>Pour 500 mL of deionized water into a 1 L beaker with constant agitation; add 0.3 mL of hydrochloric acid at a 36.5% concentratio...

<ol>
	<li>Venkataramanan, V., Maheswaran, S., Sherwood, J. N., Bhat, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crystal+growth+and+physical+characterization+of+the+semiorganic+bis(thiourea)+cadmium+chloride.">Crystal growth and physical characterization of the semiorganic bis(thiourea) cadmium chloride.</a> Journal of Crystal Growth. 179 (3-4), 605-610 (1997).</li><li>Ushasree, P. M., Muralidharan, R., Jayavel, R., Ramasamy, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+bis(thiourea)+cadmium+chloride+single+crystals+a+potential+NLO+material+of+organometallic+complex.">Growth of bis(thiourea) cadmium chloride single crystals a potential NLO material of organometallic complex.</a> Journal of Crystal Growth. 218 (2-4), 365-371 (2000).</li><li>Ushasree, P. M., Jayavel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+and+micromorphology+of+as-grown+and+etched+bis(thiourea)+cadmium+chloride+(BTCC)+single+crystals.">Growth and micromorphology of as-grown and etched bis(thiourea) cadmium chloride (BTCC) single crystals.</a> Optical Materials. 21 (1-3), 569-604 (2002).</li><li>Pawar, S. M., Pawar, B. S., Kim, J. H., Joo, O., Lokhande, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+status+of+chemical+bath+deposited+metal+chalcogenide+and+metal+oxide+thin+films.">Recent status of chemical bath deposited metal chalcogenide and metal oxide thin films.</a> Current Applied Physics. 11 (2), 117-161 (2011).</li><li>Suriakarthick, R., Kumar, V. N., Shyju, T. S., Gopalakrishnan, R. <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+post+annealed+copper+sulfide+thin+films+from+photochemical+deposition+technique.">Investigation on post annealed copper sulfide thin films from photochemical deposition technique.</a> Materials Science in Semiconductor Processing. 26 (1), 155-161 (2014).</li><li>Podder, J., Kobayashi, R., Ichimura, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photochemical+deposition+of+Cu+x+S+thin+films+from+aqueous+solutions.">Photochemical deposition of Cu x S thin films from aqueous solutions.</a> Thin Solid Films. 472 (1-2), 71-75 (2005).</li><li>Gunasekaran, M., Gopalakrishnan, R., Ramasamy, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deposition+of+ZnS+thin+films+by+photochemical+deposition+technique.">Deposition of ZnS thin films by photochemical deposition technique.</a> Materials Letters. 58 (1-2), 67-70 (2004).</li><li>Ichimura, M., Goto, F., Ono, Y., Arai, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deposition+of+CdS+and+ZnS+from+aqueous+solutions+by+a+new+photochemical+technique.">Deposition of CdS and ZnS from aqueous solutions by a new photochemical technique.</a> Journal of Crystal Growth. 198 (1), 308-312 (1999).</li><li>Kumaresan, R., Ichimura, M., Sato, N., Ramasamy, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+novel+photochemical+deposition+technique+for+the+deposition+of+indium+sulfide.">Application of novel photochemical deposition technique for the deposition of indium sulfide.</a> Materials Science Engineering: B. 96 (1), 37-42 (2002).</li><li>Rama, G., Jeevanandam, P. <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+different+morphologies+of+CdS+nanoparticles+by+thermal+decomposition+of+bis(thiourea)cadmium+chloride+in+various+solvents.">Evolution of different morphologies of CdS nanoparticles by thermal decomposition of bis(thiourea)cadmium chloride in various solvents.</a> Journal of Nanoparticle Research. 17 (1), 1-13 (2015).</li><li>Pabitha, G., Dhanasekaran, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+and+characterization+of+a+nonlinear+optical+crystal+-+bis+thiourea+cadmium+chloride.">Growth and characterization of a nonlinear optical crystal - bis thiourea cadmium chloride.</a> International Journal of Innovative Research in Science, Engineering and Technology. 4 (1), 34-38 (2015).</li><li>Trujillo, L. E., 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=Di-thiourea+cadmium+chloride+crystals+synthesis+under+UV+radiation+influence.">Di-thiourea cadmium chloride crystals synthesis under UV radiation influence.</a> Journal of Crystal Growth. 478 (1), 140-145 (2017).</li><li>Elilarassi, R., Maheshwari, S., Chandrasekaran, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+optical+characterization+of+CdS+nanoparticles+synthesized+using+a+simple+chemical+reaction+route.">Structural and optical characterization of CdS nanoparticles synthesized using a simple chemical reaction route.</a> Optoelectronics and Advanced Materials - Rapid Communications. 4 (3), 309-312 (2010).</li><li>Selvasekarapandian, S., Vivekanandan, K., Kolandaivel, P., Gundurao, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vibrational+Studies+of+Bis(thiourea)+Cadmium+Chloride+and+Tris(thiourea)+Zinc+Sulphate+Semiorganic+Non-linear+Optical+Crystals.">Vibrational Studies of Bis(thiourea) Cadmium Chloride and Tris(thiourea) Zinc Sulphate Semiorganic Non-linear Optical Crystals.</a> Crystal Research &amp; Technology. 32 (2), 299-309 (1997).</li></ol>

The discussion presented in this section focuses only on the protocol and not on the results already shown in the representative results.
One of the most critical parts of the protocol is the preparation of the precursor solution. It is fundamental to maintain an acidic pH to avoid the Cd(OH)2 formation. If the pH is not acidic, it leads to the direct formation of CdS due to the thiourea dissociation and the Cd(OH)2 formation. 
The second most important step is step ...

An important area of research is single crystals; their growth is aimed at different applications. These can be used as non-linear optical materials applied in the areas of laser technology, in the field of optoelectronics, and for the storage of information1, which provides an area of opportunity for their investigation. Bis(thiourea) cadmium chloride is a metal-organic material and can be synthesized from two precursors, thiourea and cadmium chloride, obeying the following chemical formula: 2CS(NH2)2 + CdCl2 CdCl2-[CS(NH2)2]2. This metal-organic material has been prepared under different reaction conditions, such as temperature and pH, but never with the assistance of ultraviolet (UV) light.
The influence of pH on the structure of the crystal has been reported; at a pH &#60; 6, it is possible to obtain the formation of monocrystals. These, in turn, are modified depending on the pH range. At an interval of 6 to 4, it is possible to obtain hexagonal structures, for if pH is &#60; 4, an orthorhombic crystalline structure is obtained2. The ion dissociation is promoted by the acidic pH Cd2+ and Cl- since it prevents cadmium hydroxide formation [Cd(OH)2]. This stabilizes the cadmium: a cadmium atom joins with two sulfur-free radicals and two chlorines.
Here, the synthesis is carried out using the chemical bath deposition technique (CBD), controlling the different conditions that intervene at the time of the chemical reaction3. In CBD, the factors that control the chemical reaction are the following: the solution temperature, the precursor ions, the solution pH, the number of reagents, and the agitation speed, to name a few. On the other hand, the compared technique used here is called photochemical bath deposition (PCBD) because it uses UV light assistance. There have been reports in which UV light assistance has been used to synthesize films of CuSx4,5, ZnS6, CdS7, and InS8, among others. Ichimura and Gunasekaran9 present in their work that sulfate solutions have an absorption edge close to 300 nm. Due to this absorption range, ultraviolet radiation is applied, which results in a similar emission range to that of the absorbed solutions.
Another property of bis(thiourea) cadmium chloride is its degradation when heated. It exhibits an initial decomposition at temperatures of 512 K and above, forming cadmium sulfide (CdS). The degradation reaction is as follows: [Cd(CS[NH2])2]Cl2 &#8594; &#916; CdS + HNCS + NH3 + NH4SCN. This degradation generates thiocyanuric acid and various thiocyanates10,11. Also, in the research group, some effects caused by the UV radiation were studied12. Last, in this work, a comparative synthesis procedure for bis(thiourea) cadmium chloride crystals is described, as well as the effects of UV light.

<table>
	<tbody>
		<tr>
			<td>Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cadmium chloride Anh. ACS, 99.4 %</td>
			<td>Fermont</td>
			<td>PQ24291</td>
			<td>Highly toxic</td>
		</tr>
		<tr>
			<td>Thiourea technical grade, 99.9 %</td>
			<td>Reasol</td>
			<td>R5913</td>
			<td>Toxic</td>
		</tr>
		<tr>
			<td>Hydrochloric acid, 36.5 &#8211; 38.0 %</td>
			<td>J.T.Baker</td>
			<td>MFCD00011324</td>
			<td>Highly corrosive liquid</td>
		</tr>
		<tr>
			<td>Material</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Filter paper</td>
			<td>Whatman</td>
			<td>1440 125</td>
			<td>40, Ashless, Circles, 125 mm</td>
		</tr>
		<tr>
			<td>Beaker</td>
			<td>Kimax</td>
			<td>1400</td>
			<td>100 mL</td>
		</tr>
		<tr>
			<td>Volumetric Flask</td>
			<td>Kimax</td>
			<td>28012-100</td>
			<td>Class A 100 mL</td>
		</tr>
		<tr>
			<td>Glass Funnel</td>
			<td>Kimax</td>
			<td>28980-150</td>
			<td>Addition Funnel, Long Stem, 60&#176; Angle, Wide Top. Type I, Class B.</td>
		</tr>
		<tr>
			<td>Watch glasses</td>
			<td>Pyrex</td>
			<td>9985-150</td>
			<td>Corning, 150&#160;mm</td>
		</tr>
		<tr>
			<td>Crucibles</td>
			<td>Fisherbrand</td>
			<td>FB-965-D</td>
			<td>High-Form Porcelain</td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Furnace</td>
			<td>Briteg Instrumentos Cientificos S.A. de C.V.</td>
			<td>1010</td>
			<td></td>
		</tr>
		<tr>
			<td>Fume Hood</td>
			<td>Fisher Alders, S.A. de C.V.</td>
			<td>F1124</td>
			<td></td>
		</tr>
		<tr>
			<td>Light surce</td>
			<td>Philips</td>
			<td>PL-S 9W UV-A/2P 1CT/6X 10 CC</td>
			<td></td>
		</tr>
		<tr>
			<td>pH meter</td>
			<td>OAKTON</td>
			<td>WD-35419-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Hotplate whit magnetic stirrer</td>
			<td>Cole-Parmer</td>
			<td>JZ-04660-75</td>
			<td></td>
		</tr>
	</tbody>
</table>

the effect of ultraviolet radiation on the chemical bath deposition of bis(thiourea) cadmium chloride crystals and the subsequent cds obtention

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of 367 nm using the chemical bath deposition technique are studied comparatively. Two experiments are performed to make a comparison: one without UV light and the other with the aid of UV light. Both experiments are performed under equal conditions, at a temperature of 343 K and with a pH of 3.2. The precursors used are cadmium chloride (CdCl2) and thiourea [CS(NH2)2], which are dissolved in 50 mL of deionized water with an acidic pH. In this experiment, the interaction of electromagnetic radiation is sought at the moment the chemical reaction is carried out. The results demonstrate the existence of an interaction between the crystals and the UV light; the UV light assistance causes crystal growths in an acicular shape. Also, the final product obtained is cadmium sulfide and shows no evident difference when synthesized with or without the use of UV light.

The UV-Vis diffusion&#39;s reflectance absorption spectra in both precursor solutions, A and B, show the existence of a bis(thiourea) cadmium chloride complex&#8212;CdCl2-(CS(NH2)2)2. This is evidenced by a broad absorption band within the range of 250 - 500 nm in Figure 2c. In turn, Figure 2c is the combination of the main absorption bands of the isolated CdCl2 and CS(NH<sub...

Watch this Scientific Journal Video about The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bisthiourea Cadmium Chloride Crystals and the Subsequent CdS Obtention at JoVE.com

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bisthiourea Cadmium Chloride Crystals and the Subsequent CdS Obtention

This article presents a protocol for the synthesis of bis(thiourea) cadmium chloride crystals by chemical bath deposition. Two experiments are described: one aided by ultraviolet light compared to one without ultraviolet light.

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bis(thiourea) Cadmium Chloride Crystals and the Subsequent CdS Obtention

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of ...

This method can help answer key questions on the crystal world-field. Such as interaction of UV light and the world of bis-thiourea cadmium chloride crystals. The main advantage of this technique is that it's possible to modify the morphology of bis-thiourea cadmium chloride crystals.Demonstrating the procedure will be MCM Luis Eduardo Trujillo-Villanueva. A grad student of our laboratory. First, pour 500 milliliters of deionized water into a one liter beaker, with constant agitation.Then add 3 milliliters of 36.5%hydrochloric acid. Making sure that the ph of this solution is as close as possible to three. Next, pour 50 milliliters of the pre-cursor solution into two 100 milliliter beakers labeled A and B.Add 2.29 grams of cadmium chloride and 1.33 grams of thiourea in each beaker.Following this, place beaker A on a stirring hot plate and heat to 334 kelvin;with moderate stirring speed for two hours. Place beaker B on a stirring hot plate and heat to 334 kelvin, with moderate stirring. Turn on the UV light source and allow the reaction to proceed for two hours.Place a glass funnel with filter paper on two 100 milliliter volumetric flasks. Immediately filter each solution from beakers A and B, into separate flasks. Filter the solutions quickly, because the cooling initiates the crystal growth.Now allow both solutions to cool to room temperature. Place a glass funnel with filter paper on two new 100 milliliter volumetric flasks. Filter the solutions with the crystals into separate flasks.Transfer the crystals from the filter paper to separate watch glasses. Place the crystals into two separate crucibles labeled A and B.Preheat an electric laboratory furnace and stabilize its temperature at 773 kelvin or higher. Once the furnace temperature is stabilized, place the crucibles containing the crystals inside the furnace.After one hour, turn off the furnace and allow it to cool to room temperature. Then remove the crucibles containing the crystals from the furnace. The UV-vis diffusions reflectance absorption spectra in both pre-cursor solutions, show the bis-thiourea cadmium chloride complex, which is evidenced by a broad absorption band from 250 to 500 nanometers.The cadmium chloride and thiourea absorption bands are also observed in the spectra of the complex. The Raman spectra of the crystals display peaks corresponding to the cadmium chlorine nitrogen carbon sulfur and carbon sulfur bonds. Although the same bonds are observed for both experiments, such intensities are lower without UV assistance.Which indicates a smaller number of bonds. The XRD pattern shows preferential growth in the zero two zero and zero zero one planes with UV light;which corresponds to sulfur and cadmium atoms, within the complex, respectively. The SEM images show that acicular crystals, four to six times larger, are formed with UV light.TGA analysis of the crystals exhibits a similar behavior for both the UV and non-UV assisted experiments. DRX of the calcium complex shows no differences in the cadmium sulfide, obtained by chemical bath deposition versus photo-chemical bath deposition. A slightly more prominent average particle size for photo-chemical bath deposition is observed.Demonstrating that UV light promotes sulfur incorporation into the cadmium. The UV light promotes chemical balance between cadmium and sulfur-ions, which causes preferential growth in the crystallized total of the bis-thiourea cadmium chloride crystals. The cadmium sulfide obtained after calcination showed no evident difference.

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Origami Inspired Self-assembly of Patterned and Reconfigurable Particles

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two dimensional (2D) structures. These technologies are mature, offer high precision and many of them can be implemented in a high-throughput manner. We leverage the advantages of planar lithography and combine them with self-folding methods1-20 wherein physical forces derived from surface tension or residual stress, are used to curve or fold planar structures into three dimensional (3D) structures. In doing so, we make it possible to mass produce precisely patterned static and reconfigurable particles that are challenging to synthesize.
In this paper, we detail visualized experimental protocols to create patterned particles, notably, (a) permanently bonded, hollow, polyhedra that self-assemble and self-seal due to the minimization of surface energy of liquefied hinges21-23 and (b) grippers that self-fold due to residual stress powered hinges24,25. The specific protocol described can be used to create particles with overall sizes ranging from the micrometer to the centimeter length scales. Further, arbitrary patterns can be defined on the surfaces of the particles of importance in colloidal science, electronics, optics and medicine. More generally, the concept of self-assembling mechanically rigid particles with self-sealing hinges is applicable, with some process modifications, to the creation of particles at even smaller, 100 nm length scales22, 26 and with a range of materials including metals21, semiconductors9 and polymers27. With respect to residual stress powered actuation of reconfigurable grasping devices, our specific protocol utilizes chromium hinges of relevance to devices with sizes ranging from 100 &mu;m to 2.5 mm. However, more generally, the concept of such tether-free residual stress powered actuation can be used with alternate high-stress materials such as heteroepitaxially deposited semiconductor films5,7 to possibly create even smaller nanoscale grasping devices.

We describe experimental details of the synthesis of patterned and reconfigurable particles from two dimensional (2D) precursors. This methodology can be used to create particles in a variety of shapes including polyhedra and grasping devices at length scales ranging from the micro to centimeter scale.

There are numerous techniques such as photolithography, electron-beam lithography and soft-lithography that can be used to precisely pattern two ...

Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS can be subdivided into three domains: the distal O-polysaccharide, a core oligosaccharide, and the lipid A domain consisting of a lipid A molecular species and 3-deoxy-D-manno-oct-2-ulosonic acid residues (Kdo). The lipid A domain is the only component essential for bacterial cell survival. Following its synthesis, lipid A is chemically modified in response to environmental stresses such as pH or temperature, to promote resistance to antibiotic compounds, and to evade recognition by mediators of the host innate immune response. The following protocol details the small- and large-scale isolation of lipid A from gram-negative bacteria. Isolated material is then chemically characterized by thin layer chromatography (TLC) or mass-spectrometry (MS). In addition to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS, we also describe tandem MS protocols for analyzing lipid A molecular species using electrospray ionization (ESI) coupled to collision induced dissociation (CID) and newly employed ultraviolet photodissociation (UVPD) methods. Our MS protocols allow for unequivocal determination of chemical structure, paramount to characterization of lipid A molecules that contain unique or novel chemical modifications. We also describe the radioisotopic labeling, and subsequent isolation, of lipid A from bacterial cells for analysis by TLC. Relative to MS-based protocols, TLC provides a more economical and rapid characterization method, but cannot be used to unambiguously assign lipid A chemical structures without the use of standards of known chemical structure. Over the last two decades isolation and characterization of lipid A has led to numerous exciting discoveries that have improved our understanding of the physiology of gram-negative bacteria, mechanisms of antibiotic resistance, the human innate immune response, and have provided many new targets in the development of antibacterial compounds.

Isolation and characterization of the lipid A domain of lipopolysaccharide (LPS) from gram-negative bacteria provides insight into cell surface based mechanisms of antibiotic resistance, bacterial survival and fitness, and how chemically diverse lipid A molecular species differentially modulate host innate immune responses.

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS ...

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in traditional materials, including low cost and mechanical flexibility. In a similar vein, it would be advantageous to expand the use of organics into high frequency electronics and spin-based electronics. This work presents a synthetic process for the growth of thin films of the room temperature organic ferrimagnet, vanadium tetracyanoethylene (V[TCNE]x, x~2) by low temperature chemical vapor deposition (CVD). The thin film is grown at &#60;60 &#176;C, and can accommodate a wide variety of substrates including, but not limited to, silicon, glass, Teflon and flexible substrates. The conformal deposition is conducive to pre-patterned and three-dimensional structures as well. Additionally this technique can yield films with thicknesses ranging from 30 nm to several microns. Recent progress in optimization of film growth creates a film whose qualities, such as higher Curie temperature (600 K), improved magnetic homogeneity, and narrow ferromagnetic resonance line-width (1.5 G) show promise for a variety of applications in spintronics and microwave electronics.

We present the synthesis of the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x, x~2) via low temperature chemical vapor deposition (CVD). This optimized recipe yields an increase in Curie temperature from 400 K to over 600 K and a dramatic improvement in magnetic resonance properties.

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Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Dynamic Electrochemical Measurement of Chloride Ions

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement, long-term and continuous monitoring is limited due to the inherent drift and the requirement of a stable reference electrode. We utilized the chronopotentiometric approach to minimize drift and avoid the use of a conventional reference electrode. A galvanostatic pulse is applied to an Ag/AgCl electrode which initiates a faradic reaction depleting the Cl&#713; ions near the electrode surface. The transition time, which is the time to completely deplete the ions near the electrode surface, is a function of the ion concentration, given by the Nernst equation. The square root of the transition time is in linear relation to the chloride ion concentration. Drift of the response over two weeks is negligible (59 &#181;M/day) when measuring 1 mM [Cl&#713;]using a current pulse of 10 Am-2. This is a dynamic measurement where the moment of transition time determines the response and thus is independent of the absolute potential. Any metal wire can be used as a pseudo-reference electrode, making this approach feasible for long-term measurement inside concrete structures.

Dynamic measurement of chloride ions is presented. Transition time of an Ag/AgCl electrode, during a chronopotentiometric technique, can give the concentration of chloride ions in electrolyte. This method does not require a stable conventional reference electrode.

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

The Effect of Interfacial Chemical Bonding in TiO2-SiO2 Composites on Their Photocatalytic NOx Abatement Performance

The chemical bonding of particulate photocatalysts to supporting material surfaces is of great importance in engineering more efficient and practical photocatalytic structures. However, the influence of such chemical bonding on the optical and surface properties of the photocatalyst and thus its photocatalytic activity/reaction selectivity behavior has not been systematically studied. In this investigation, TiO2 has been supported on the surface of SiO2 by means of two different methods: (i) by the in situ formation of TiO2 in the presence of sand quartz via a sol-gel method employing tetrabutyl orthotitanium (TBOT); and (ii) by binding the commercial TiO2 powder to quartz on a surface silica gel layer formed from the reaction of quartz with tetraethylorthosilicate (TEOS). For comparison, TiO2 nanoparticles were also deposited on the surfaces of a more reactive SiO2 prepared by a hydrolysis-controlled sol-gel technique as well as through a sol-gel route from TiO2 and SiO2 precursors. The combination of TiO2 and SiO2, through interfacial Ti-O-Si bonds, was confirmed by FTIR spectroscopy and the photocatalytic activities of the obtained composites were tested for photocatalytic degradation of NO according to the ISO standard method (ISO 22197&#8722;1). The electron microscope images of the obtained materials showed that variable photocatalyst coverage of the support surface can successfully be achieved but the photocatalytic activity towards NO removal was found to be affected by the preparation method and the nitrate selectivity is adversely affected by Ti-O-Si bonding.

The Effect of Interfacial Chemical Bonding in TiO2-SiO2 Composites on Their Photocatalytic NOx Abatement Performance

The focus of the present work is to establish means to generate and quantify levels of Ti-O-Si linkages and to correlate these with the photocatalytic properties of the supported TiO2.

The chemical bonding of particulate photocatalysts to supporting material surfaces is of great importance in engineering more efficient and practical ...

Extraction of Lignin with High &#946;-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield

Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the emerging elegant procedures to obtain specific aromatic products rely on the lignin substrate having a high content of the readily cleavable &#946;-O-4 linkage as present in the native lignin structure. This provides a miss-match with typical technical lignins that are highly degraded and therefore are low in &#946;-O-4 linkages. Therefore, the extraction yields, and the quality of the obtained lignin are of utmost importance to access new lignin valorization pathways. In this manuscript, a simple protocol is presented to obtain lignins with high &#946;-O-4 content by relatively mild ethanol extraction that can be applied to different lignocellulose sources. Furthermore, analysis procedures to determine the quality of the lignins are presented together with a depolymerization protocol that yields specific phenolic 2-arylmethyl-1,3-dioxolanes, which can be used to evaluate the obtained lignins. The presented results demonstrate the link between lignin quality and potential for the lignins to be depolymerized into specific monomeric aromatic chemicals. Overall, the extraction and depolymerization demonstrates a trade-off between the lignin extraction yield and the retention of the native aryl-ether structure and thus the potential of the lignin to be used as the substrate for the production of chemicals for higher-value applications.

Extraction of Lignin with High &amp;#946;-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield

Here, we present a protocol to perform ethanol extraction of lignin from several biomass sources. The effect of the extraction conditions on the lignin yield and &#946;-O-4 content are presented. Selective depolymerization is performed on the obtained lignins to obtain high aromatic monomer products.

Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the ...