We thank for the National Key R&#38;D Program of China (2018YFA0901700), Natural Science Foundation of Jiangsu Province (Grants No. BK20160167), the Thousand Talents Plan (Young Professionals), the Fundamental Research Funds for the Central Universities (JUSRP51712B), the National First-class Discipline Program of Light Industry Technology and Engineering (LITE2018-14) and Postdoctoral Foundation in Jiangsu Province (2018K153C) for the funding support.

NOTE: &#945;-Halo-N-acyl-hydrazones were prepared according to a published procedure60. All the solvents and other chemical reagents were obtained from commercial sources without further purification. We first described the synthesis of &#945;-Halo-N-acyl-hydrazones and the biosynthesis of cercosporin as a metal-free photocatalyst. Next, we illustrated the protocols of the cercosporin-photocatalyzed reactions for the synthesis of 1,2,3-thiadiazoles and 1,4,5,6-tetrahydropyridazines.
CAUTION: All the manipulation should be conducted cautiously wearing gloves, lab-coat, and goggles. It is highly recommended to carefully read the MSDS for each chemical and solvent used in those reactions and purification process. Chemicals can be weighed out on a balance on the bench. All the organic reactions should be set up in the fume hood and the purification process should also be carried out in a fume hood.
1. Preparation of &#945;-Halo-N-acyl-hydrazones
<ol>
	<li>Weigh out 10 mmol of ketone and 10 mmol of benzoyl hydrazine into a flask.</li>
	<li>Add 20 mL of CH3OH to the flask.</li>
	<li>Equip the flask with a rubber stopper and a stirring bar.</li>
	<li>Inject 0.25 mL of HCl slowly into the mixture.</li>
	<li>Incubate the flask in the air at room temperature for 4 h.</li>
	<li>Collect the precipitate after reaction by filtration and wash with acetone.</li>
	<li>Dry the product by vacuum and identify by NMR.</li>
</ol>
2. Preparation of cercosporin
<ol>
	<li>Charge a 3 L shake flask with 1 L of S-7 medium.</li>
	<li>Inoculate the cercosporin-producing strain56 into the shake flask.</li>
	<li>Culture the mixture under light conditions at 135 r/min, 25 &#176;C for 2 weeks.</li>
	<li>Subject the fermentation broth to vacuum filtration using a vacuum pump to obtain the supernatant and pellet.</li>
	<li>Collect the pellet and dry it in a freeze dryer.</li>
	<li>Extract the pellet and the supernatant separately with 3 x 50 mL of dichloromethane.</li>
	<li>Combine the organic phases and wash with water 2-3 times.</li>
	<li>Concentrate the organic phase under vacuum.</li>
	<li>Re-dissolve the residue with analytical methanol, and filter through a 0.18 &#181;m organic microfiltration membrane.</li>
	<li>Purify the cercosporin with a Sephadex LH-20 column and identify by HPLC.</li>
</ol>
3. Preparation of 1,2,3-thiadiazoles
<ol>
	<li>Weigh out the &#945;-Halo-N-acyl-hydrazone (0.2 mmol, 1.0 eq), 1 mg of cercosporin (0.002 mmol, 0.01 equiv.), 27 mg of tBuOK (1.2 equiv) and 39 mg of KSCN (2 equiv) into a 10 mL Schlenk tub equipped with a rubber stopper and a stirring bar.</li>
	<li>Purge the Schlenk tube with O2 three times.</li>
	<li>Inject dry CH3CN (2 mL) to the Schlenk tube.</li>
	<li>Subject the Schlenk tube to a 5 W blue LED from the bottom for 16 h.</li>
	<li>Wash with 4 x 15 mL of saturated NaCl solution and combine the aqueous phase.</li>
	<li>Re-extract the aqueous phase with 4 x 15 mL of ethyl acetate.</li>
	<li>Combine organic phase and dry with anhydrous Na2SO4.</li>
	<li>Remove the solvent with vacuum evaporator.</li>
	<li>Purify the product 3 by silica gel column chromatography (eluent, petroleum: ethyl acetate = 10:1) and identify by NMR.</li>
</ol>
4. Preparation of 1,4,5,6-tetrahydropyridazine
<ol>
	<li>Weigh out the &#945;-Halo-N-acyl-hydrazone (0.5 mmol), 2.7 mg of cercosporin (0.01 equiv), and 195 mg of Cs2CO3 (1.2 equiv) into a 10 mL Schlenk tub equipped with a rubber stopper and a stirring bar.</li>
	<li>Purge the Schlenk tube with N2 three times.</li>
	<li>Inject CH3CN/H2O (10:1, 2 mL) to the Schlenk tube.</li>
	<li>Subject the Schlenk tube to a 5 W blue LED from the bottom for 16 h.</li>
	<li>Wash with 4 x 15 mL of saturated NaCl solution and combine the aqueous phase.</li>
	<li>Re-extract the aqueous phase with 4 x 15 mL of ethyl acetate.</li>
	<li>Combine organic phase and dry with anhydrous Na2SO4.</li>
	<li>Remove the solvent with vacuum evaporator.</li>
	<li>Purify the product 4 by silica gel column chromatography (eluent, petroleum: ethyl acetate = 10:1) and identify by NMR.</li>
</ol>

The authors have nothing to disclose.

Nitrogen-containing heterocycles are important motifs for many new drugs and were traditionally synthesized through thermal cycloaddition reactions. Due to great interest, a new photocatalytic method for the synthesis of these compounds is highly desired. To take advantage of the excellent photosensitization properties of cercosporin, we applied cercosporin as a metal-free photocatalyst in two categories of annulation reactions to synthesize nitrogen-containing heterocycles.
First, we reported...

Nitrogen-containing heterocycles have drawn much attention since they are not only important skeletons for a wide range of natural products with bioactivities, but also the synthetic precursors for agrochemicals and drug molecules1,2. Among the various N-heterocycles, 1,2,3-thiadiazoles3,4 and 1,4,5,6-tetrahydropyridazines5,6 are the most important molecules, which are utilized as versatile intermediates in the synthetic chemistry (Figure 1). Since modification of their functional groups always induces distinctive pharmacological activities, extensive efforts have been devoted to developing effective strategies for the synthesis of nitrogen-containing heterocycles and they were mostly synthesized through thermal cycloaddition reactions7,8,9,10. Nowadays, to meet the requirements of sustainable development and green chemistry, photocatalysis has exerted great importance and advantages11,12,13,14, which includes effectiveness15,16,17,18,19 and avoidance of stoichiometric reagents for the activation20,21. The powerful and versatile four-unit intermediates, azoalkenes (1,2-diaza-1,3-dienes)22,23,24,25,26,27,28,29, have been employed as precursors in metal-based Ru(bpy)3Cl2-photocatalyzed reactions with high efficiency for the annulation of halogeno hydrazine and ketocarbonyls30. Furthermore, it was also used in the metal-free Eosin Y photocatalyzed system, but affording the desired product in only 7% yield. Since metal-free photocatalysts show great advantage over transition metal-based photocatalysts, regarding to the environmental factor as well as the cheaper prices18,19, it is highly important to develop new metal-free photocatalytic systems for the synthesis of N-heterocycles.
Cercosporin31,32,33,34,35, hypocrellin36,37,38,39,40, elsinochrome41 and phleichrome42,43 (Figure 2) belong to perylenequinonoid pigments (PQPs) in nature and are produced by endophytic fungi, which have been widely investigated regarding to their photophysical and photobiological properties, and applied in photodynamic therapy and photophysical diagnosis, due to their strong absorption in UV-vis region and unique properties of photosensitization36,44,45,46,47. Upon irradiation, those PQPs can be prompted to excited state and then generate active species through energy transfer (EnT) and electron transfer (ET)35,38,44,48,49,50,51,52,53,54. Thus, we envisioned that these natural PQPs may be utilized as &#34;metal-free&#34; photocatalysts to drive organic reactions, which have rarely been investigated55,56,57,58,59.
Herein, we report the protocol for the biosynthesis of cercosporin from liquid fermentation and then apply it as a metal-free photocatalyst for the [4+1] annulation reaction of azoalkenes and KSCN, as well as the [4+2] cyclodimerization of azoalkenes, which supply 1,2,3-thiadiazoles and 1,4,5,6- tetrahydropyridazines with high efficiency under mild conditions, respectively (Figure 3).

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2,4&#39;-Dibromoacetophenone</td>
			<td>ENERGY</td>
			<td>D0500850050</td>
			<td></td>
		</tr>
		<tr>
			<td>2&#39;-bromo-4-chloroacetophenone</td>
			<td>ENERGY</td>
			<td>A0500400050</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Bromo-4&#39;-fluoroacetophenone</td>
			<td>ENERGY</td>
			<td>A050037-5g</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Bromoacetophenone</td>
			<td>ENERGY</td>
			<td>A0500870050</td>
			<td></td>
		</tr>
		<tr>
			<td>4-Bromobenzhydrazide</td>
			<td>ENERGY</td>
			<td>B0103390010</td>
			<td></td>
		</tr>
		<tr>
			<td>4-Chlorobenzhydrazide</td>
			<td>ENERGY</td>
			<td>D0511130050</td>
			<td></td>
		</tr>
		<tr>
			<td>4-Fluorobenzhydrazide</td>
			<td>ENERGY</td>
			<td>B010461-5g</td>
			<td></td>
		</tr>
		<tr>
			<td>5 W blue LED</td>
			<td>PHILIPS</td>
			<td>29237328756</td>
			<td></td>
		</tr>
		<tr>
			<td>Benzoyl hydrazine</td>
			<td>ENERGY</td>
			<td>D0500610250</td>
			<td></td>
		</tr>
		<tr>
			<td>CH2Cl2</td>
			<td>SINOPHARM</td>
			<td>80047360</td>
			<td></td>
		</tr>
		<tr>
			<td>CH3CN</td>
			<td>SINOPHARM</td>
			<td>S3485101</td>
			<td></td>
		</tr>
		<tr>
			<td>CH3OH</td>
			<td>SINOPHARM</td>
			<td>100141190</td>
			<td></td>
		</tr>
		<tr>
			<td>Cs2CO3</td>
			<td>ENERGY</td>
			<td>E060058-25g</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl acetate</td>
			<td>SINOPHARM</td>
			<td>40065986</td>
			<td></td>
		</tr>
		<tr>
			<td>freeze dryer</td>
			<td>LABCONCO</td>
			<td>7934074</td>
			<td></td>
		</tr>
		<tr>
			<td>HPLC</td>
			<td>Agilent</td>
			<td>1260 Infinity II</td>
			<td></td>
		</tr>
		<tr>
			<td>KSCN</td>
			<td>ENERGY</td>
			<td>E0104021000</td>
			<td></td>
		</tr>
		<tr>
			<td>Na2SO4</td>
			<td>SINOPHARM</td>
			<td>51024461</td>
			<td></td>
		</tr>
		<tr>
			<td>organic microfiltration membrane</td>
			<td>SINOPHARM</td>
			<td>92412511</td>
			<td></td>
		</tr>
		<tr>
			<td>S-7 medium</td>
			<td></td>
			<td></td>
			<td>Gluose 1g; Fructose 3g; Sucrose 6g; Sodium acetate 1g; Soytone 1g; Phenylalanine 5mg; Sodium benzoate 100mg; 1M KH2P04 buffer ph6.8; Biotin 1mg; Ca(NO3)2 6.5mg; Pyridoxal 1mg; Calcium pantothenate 1mg; Thiamine 1mg; MnCl2 5mg; FeCl3 2mg; Cu(NO3)2 1mg; MgSO4 3.6mg; ZnSO4 2.5mg</td>
		</tr>
		<tr>
			<td>Schlenk tub</td>
			<td>Synthware</td>
			<td>F891910</td>
			<td></td>
		</tr>
		<tr>
			<td>sephadex LH-20 column</td>
			<td>GE</td>
			<td>17009001</td>
			<td></td>
		</tr>
		<tr>
			<td>shaker</td>
			<td>Lab Tools</td>
			<td>BSH00847</td>
			<td></td>
		</tr>
		<tr>
			<td>silica gel</td>
			<td>ENERGY</td>
			<td>E011242-1kg</td>
			<td></td>
		</tr>
		<tr>
			<td>tBuOK</td>
			<td>ENERGY</td>
			<td>E0610551000</td>
			<td></td>
		</tr>
		<tr>
			<td>vacuum bump</td>
			<td>Greatwall</td>
			<td>SHB-III</td>
			<td></td>
		</tr>
		<tr>
			<td>vacuum evaporator</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

cercosporin-photocatalyzed [4+1]- and [4+2]-annulations of azoalkenes under mild conditions

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. Traditionally, they were synthesized through thermal cycloaddition reactions, whereas today, photocatalysis is preferred due to the mild and efficient conditions. With this focus, a new photocatalytic method for the synthesis of nitrogen-containing heterocycles is highly desired. Here, we report a protocol for the biosynthesis of cercosporin, which could function as a metal-free photocatalyst. We then illustrate cercosporin-photocatalyzed protocols for the synthesis of nitrogen-containing heterocycles 1,2,3-thiadiazoles through annulation of azoalkenes with KSCN, and synthesis of 1,4,5,6-tetrahydropyridazines [4+2] through cyclodimerization of azoalkenes under mild conditions, respectively. As a result, there is a new bridge between the microbial fermentation method and organic synthesis in a mild, cost-effective, environmentally friendly and sustainable manner.

Synthesis of &#945;-Halo-N-acyl-hydrazones: They are synthesized according to Protocol 1.
Synthesis of cercosporin: It was synthesized and purified according to Protocol 2. 1H NMR (400 MHz, CDCl3): &#948; ppm 14.82 (s, 2H, ArH), 7.06 (s, 2H, ArH), 5.57 (s, 2H, CH2), 4.20 (s, 6H, 2OCH3), 3.62-3.57 (m, 2H, CH2), 3.42-3.37 (m,...

Watch this Scientific Journal Video about Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions at JoVE.com

Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

New routes for the synthesis of nitrogen-containing heterocycles utilizing cercosporin as a metal-free photocatalyst were developed.

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. ...

cercosporin-photocatalyzed-4-1-4-2-annulations-azoalkenes-under-mild

Research

JoVE Journal

Chemistry

6.2K Views.  Jiangnan University. New routes for the synthesis of nitrogen-containing heterocycles utilizing cercosporin as a metal-free photocatalyst were developed.

Video: Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug delivery, biological imaging, and supported catalysis. In this report, we demonstrate parallel synthesis of brush-arm star polymer (BASP) nanoparticles by the &#34;brush-first&#34; method. In this method, a norbornene-terminated poly(ethylene glycol) (PEG) macromonomer (PEG-MM) is first polymerized via ring-opening metathesis polymerization (ROMP) to generate a living brush macroinitiator. Aliquots of this initiator stock solution are added to vials that contain varied amounts of a photodegradable bis-norbornene crosslinker. Exposure to crosslinker initiates a series of kinetically-controlled brush+brush and star+star coupling reactions that ultimately yields BASPs with cores comprised of the crosslinker and coronas comprised of PEG. The final BASP size depends on the amount of crosslinker added. We carry out the synthesis of three BASPs on the benchtop with no special precautions to remove air and moisture. The samples are characterized by gel permeation chromatography (GPC); results agreed closely with our previous report that utilized inert (glovebox) conditions. Key practical features, advantages, and potential disadvantages of the brush-first method are discussed.

Poly(ethylene glycol) (PEG) brush-arm star polymers (BASPs) with narrow mass distributions and tunable nanoscopic sizes are synthesized in via ring opening metathesis polymerization (ROMP) of a PEG-norbornene macromonomer followed by transfer of portions of the resulting living brush initiator to vials containing varied amounts of a rigid, photo-cleavable bis-norbornene crosslinker.

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug ...

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions

Dichloro-bis(aminophosphine) complexes of palladium with the general formula of [(P{(NC5H10)3-n(C6H11)n})2Pd(Cl)2] (where n = 0-2), belong to a new family of easy accessible, very cheap, and air stable, but highly active and universally applicable C-C cross-coupling catalysts with an excellent functional group tolerance. Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium [(P(NC5H10)3)2Pd(Cl)2] (1), the least stable complex within this series towards protons; e.g. in the form of water, allows an eased nanoparticle formation and hence, proved to be the most active Heck catalyst within this series at 100 &#176;C and is a very rare example of an effective and versatile catalyst system that efficiently operates under mild reaction conditions. Rapid and complete catalyst degradation under work-up conditions into phosphonates, piperidinium salts and other, palladium-containing decomposition products assure an easy separation of the coupling products from catalyst and ligands. The facile, cheap, and rapid synthesis of 1,1',1"-(phosphinetriyl)tripiperidine and 1 respectively, the simple and convenient use as well as its excellent catalytic performance in the Heck reaction at 100 &#176;C make 1 to one of the most attractive and greenest Heck catalysts available.
We provide here the visualized protocols for the ligand and catalyst syntheses as well as the reaction protocol for Heck reactions performed at 10 mmol scale at 100 &#176;C and show that this catalyst is suitable for its use in organic syntheses.

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1&#039;,1&#039;&#039;-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium [(P(NC5H10)3)2Pd(Cl)2] (1) is an easy accessible, cheap, and air stable, but highly active Heck catalyst with an excellent functional group tolerance that efficiently operates under mild reaction conditions to give the coupling products in very high yields.

Dichloro-bis(aminophosphine) complexes of palladium with the general formula of [(P{(NC5H10)3-n(C6H11)n})2Pd(Cl)2] (where n = 0-2), belong to a new family ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Major and severe accidents have occurred three times in nuclear power plants (NPPs), at Three Mile Island (USA, 1979), Chernobyl (former USSR, 1986) and Fukushima (Japan, 2011). Research on the causes, dynamics, and consequences of these mishaps has been performed in a few laboratories worldwide in the last three decades. Common goals of such research activities are: the prevention of these kinds of accidents, both in existing and potential new nuclear power plants; the minimization of their eventual consequences; and ultimately, a full understanding of the real risks connected with NPPs. At the European Commission Joint Research Centre&#39;s Institute for Transuranium Elements, a laser-heating and fast radiance spectro-pyrometry facility is used for the laboratory simulation, on a small scale, of NPP core meltdown, the most common type of severe accident (SA) that can occur in a nuclear reactor as a consequence of a failure of the cooling system. This simulation tool permits fast and effective high-temperature measurements on real nuclear materials, such as plutonium and minor actinide-containing fission fuel samples. In this respect, and in its capability to produce large amount of data concerning materials under extreme conditions, the current experimental approach is certainly unique. For current and future concepts of NPP, example results are presented on the melting behavior of some different types of nuclear fuels: uranium-plutonium oxides, carbides, and nitrides. Results on the high-temperature interaction of oxide fuels with containment materials are also briefly shown.

We present experiments in which real nuclear fuel, cladding, and containment materials are laser heated to temperatures beyond 3,000 K while their behavior is studied by radiance spectroscopy and thermal analysis. These experiments simulate, on a laboratory scale, the formation of a lava-phase following a nuclear reactor core meltdown.

Major and severe accidents have occurred three times in nuclear power plants (NPPs), at Three Mile Island (USA, 1979), Chernobyl (former USSR, 1986) and ...

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable low-valent-phosphorus-containing compound acts as a useful P+ transfer agent. Unlike traditional methods employed to access low-coordinate phosphorus species which usually require pyrophoric phosphorus-containing precursors (white phosphorus, Tris(trimethylsilyl)phosphine, etc.), or harsh reducing agents (alkali metals, potassium graphite, etc.), the current approach does not involve pyrophoric or explosive reagents and can be done on large scales (&#62;20 g) in excellent yields by undergraduates with basic air-free synthetic training. The bromide counter ion is readily exchanged with other anions such as tetraphenyl borate (described herein) using typical salt metathesis reagents to obtain materials with desired properties and reactivities. The versatility of this P+ transfer approach is exemplified by the reactions of these triphosphenium precursors with an N-heterocyclic carbene and an anionic bisphosphine, each of which readily displace the neutral bisphosphine to give an NHC-stabilized phosphorus(I) cation and a phosphorus(I) containing zwitterion, respectively.

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI

The synthesis of a triphosphenium bromide salt is described and its use as a P+ transfer agent is outlined by reactions with an N-heterocyclic carbene and an anionic bisphosphine, yielding an NHC-stabilized P(I) cation and a P(I) containing zwitterion, respectively.

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to investigate the lipid raft hypothesis. Numerous studies, however, neglect the impact of physiological solution conditions. On that account, the current work presents the effect of high-salinity buffer and trans-membrane solution asymmetry on liquid-liquid phase separation in charged GUVs grown from dioleylphosphatidylglycerol, egg sphingomyelin, and cholesterol. The effects were studied under isothermal and varying temperature conditions.
We describe equipment and experimental strategies applicable for monitoring the stability of coexisting liquid domains in charged vesicles under symmetric and asymmetric high-salinity solution conditions. This includes an approach to prepare charged multicomponent GUVs in high-salinity buffer at high temperatures. The protocol entails the option to perform a partial exchange of the external solution by a simple dilution step while minimizing the vesicle dilution. An alternative approach is presented utilizing a microfluidic device that allows for a complete external solution exchange. The solution effects on phase separation were also studied under varying temperatures. To this end, we present the basic design and utility of an in-house built temperature control chamber. Furthermore, we reflect on the assessment of the GUV phase state, pitfalls associated with it and how to circumvent them.

Experiments on phase separated giant unilamellar vesicles (GUVs) frequently neglect physiological solution conditions. This work presents approaches to study the effect of high-salinity buffer on liquid-liquid phase separation in charged multicomponent GUVs as a function of trans-membrane solution asymmetry and temperature.

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to ...

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 ...

Synthesis of Terpolymers at Mild Temperatures Using Dynamic Sulfur Bonds in Poly(S-Divinylbenzene)

Elemental sulfur (S8) is a byproduct of the petroleum industry with millions of tons produced annually. Such abundant production and limited applications lead to sulfur as a cost-efficient reagent for polymer synthesis. Inverse vulcanization combines elemental sulfur with a variety of monomers to form functional polysulfides without the need for solvents. Short reaction times and straight forward synthetic methods have led to rapid expansion of inverse vulcanization. However, high reaction temperatures (&#62;160 &#176;C) limit the types of monomers that can be used. Here, the dynamic sulfur bonds in poly(S-divinylbenzene) are used to initiate polymerization at much lower temperatures. The S-S bonds in the prepolymer are less stable than S-S bonds in S8, allowing radical formation at 90 &#176;C rather than 159 &#176;C. A variety of allyl and vinyl ethers have been incorporated to form terpolymers. The resulting materials were characterized by 1H NMR, gel permeation chromatography, and differential scanning calorimetry, as well as examining changes in solubility. This method expands on the solvent-free, thiyl radical chemistry utilized by inverse vulcanization to create polysulfides at mild temperatures. This development broadens the range of monomers that can be incorporated thus expanding the accessible material properties and possible applications.

Synthesis of Terpolymers at Mild Temperatures Using Dynamic Sulfur Bonds in PolyS-Divinylbenzene

The goal of this protocol is to initiate polymerization using dynamic sulfur bonds in poly(S-divinylbenzene) at mild temperatures (90 &#176;C) without using solvents. Terpolymers are characterized by GPC, DSC and 1H NMR, and tested for changes in solubility.

Elemental sulfur (S8) is a byproduct of the petroleum industry with millions of tons produced annually. Such abundant production and limited applications ...

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number of photoactive assemblies have emerged where a photosensitizer and cobaloxime-based H2 production catalysts work in tandem to convert light energy into the H-H chemical bonds. However, the long-term instability of these assemblies and the need for hazardous proton sources have limited their usage. Here, in this work, we have integrated a stilbene-based organic dye into the periphery of a cobaloxime core via a distinct axial pyridine linkage. This strategy allowed us to develop a photosensitizer-catalyst hybrid structure with the same molecular framework. In this article, we have explained the detailed procedure of the synthesis of this hybrid molecule in addition to its comprehensive chemical characterization. The structural and optical studies have exhibited an intense electronic interaction between the cobaloxime core and the organic photosensitizer. The cobaloxime was active for H2 production even in the presence of water as the proton source. Here, we have developed a simple airtight system connected with an online H2 detector for the investigation of the photocatalytic activity by this hybrid complex. This photosensitizer-catalyst dyad present in the experimental setup continuously produced H2 once it was exposed in the natural sunlight. This photocatalytic H2 production by the hybrid complex was observed in aqueous/organic mixture media in the presence of a sacrificial electron donor under complete aerobic conditions. Thus, this photocatalysis measurement system along with the photosensitizer-catalyst dyad provide valuable insight for the development of next generation photocatalytic H2 production devices.

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

We have directly incorporated a stilbene-based organic dye into a cobaloxime core to generate a photosensitizer-catalyst dyad for photocatalytic H2 production. We have also developed a simple experimental setup for evaluating the light-driven H2 production by photocatalytic assemblies.

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number ...