Authors gratefully acknowledge the financial support of grant received from ICMR, Government of India, Delhi-110029 [No./ICMR/ 52/06/2022-BIO/BMS]. Authors would also like to thank the University Science &#38; Instrumentation facility (USIC), University of Delhi, for extending the analytical help. Kajal Sharma acknowledges the financial support received from the Department of Science and Technology through INSPIRE scheme (IF200397).

NOTE: 1-Hexadecylquinolin-1-ium bromide{[C16quin]Br} was synthesized as described previously by Sharma et al.13.
1. Preparation and sterilization of glass apparatus 
NOTE: This should be done at least 1 day prior to setting up the reaction for the synthesis of the desired compound.
<ol>
	<li>Wash a 24/29, 250 mL, two-neck round bottom flask (RB) thoroughly, along with other glass apparatus such as measuring cylinders, etc., and rinse with distilled water followed by acetone.</li>
	<li>Dry the washed apparatus in a hot air oven at 60 &#176;C until the apparatus is completely dry for further use. 
	NOTE: Usually, washed apparatus should be placed overnight in a drying oven to completely remove the water film and ensure that the reaction system is free from impurities.</li>
</ol>
2. Setting up the apparatus
NOTE: The apparatus should be clamped properly to ensure uniform heating of the reactants. The schematic diagram of the reaction set-up is demonstrated in Figure 1.
<ol>
	<li>Place an oil bath on a hot plate with a magnetic stirrer. Preheat the oil bath to 80 &#176;C before the commencement of the reaction.</li>
	<li>Allow the RB to stand in an oil bath using a tube retort stand such that it is half immersed in the oil bath placed on a hot plate with magnetic stirrer.</li>
	<li>Seal the upper mouth of the RB with a cork constituting a purging needle, further connected to a syringe with an N2 balloon attached to it.</li>
	<li>Seal the other neck of the RB tight using another rubber cork to avoid the leakage of N2 from the reaction medium.</li>
	<li>Preheat the entire medium to 80 &#176;C in an inert atmosphere maintained through N2 purging before adding the reactants to the RB.</li>
	<li>Refill the N2 balloon repeatedly to ensure the reaction system&#39;s inertness and maintain the temperature throughout (hence, oil bath heating is preferred).</li>
</ol>
3. Addition of the reactants to the reaction system
<ol>
	<li>Pour 0.1 M Quinoline and 0.105 M 1-bromohexadecane into the reaction system without disturbing the preset reaction environment.</li>
	<li>Stir the contents continuously at 2500-3000 rpm for 3 days under an inert environment and constant temperature.</li>
</ol>
4. Purification/Re-crystallization of the compound
NOTE: The entire product should not be subjected to re-crystallization. Instead, batch re-crystallization should be elected to avoid the loss of the product.
<ol>
	<li>Dissolve the obtained solid in a 1:2 toluene/ethyl ethanoate mixture. Cool this mixture to -15 &#176;C in a deep freezer (temperature set at -15 &#176;C) and filter under vacuum using a Buchner funnel, attached to a vacuum pump and a filter flask through a tubing. Place a polypropylene filter membrane, constituting a pore size of 0.45 &#181;m, in the Buchner funnel, covering the entire bottom of the filter. Pour a small amount of the solvent mixture through the filter in order to create a proper seal, preventing any sort of air leakage through the setup.</li>
	<li>Wash the filtered product with cold toluene by pouring the solvent through the funnel gradually, followed by drying at 70 &#176;C in a vacuum oven. Repeat this procedure 2x to ensure the high purity of the desired compound.</li>
</ol>
5. Validating the compound using NMR spectroscopy
<ol>
	<li>Prior to subjecting the compound to 1H NMR and 13C NMR, dissolve it in deuterated chloroform (CDCl3) by measuring 1-10 mg of the compound and dissolving it in about 1 mL of CDCl3. </li>
	<li>Inject this mixture in an NMR tube using a 1 mL syringe for analysis of the sample under an NMR spectrometer. The sample preparation is identical for both 1H NMR and 13C NMR.</li>
</ol>
6. IR characterization of the synthesized IL
<ol>
	<li>No sample preparation is required to obtain the IR spectra of the compound.</li>
	<li>Subject a few mg of the solid sample to an IR spectrometer to obtain an insight into the different functional groups present in the synthesized compound. The readings were obtained as demonstrated previously19.</li>
</ol>
7. Prediction of ADMET properties
<ol>
	<li>Enter the canonical SMILES of the desired IL into the free online software ADMETLAB 2.0 and execute the program to obtain various parameters, vindicating the biological potential of the same.</li>
</ol>
8. Disc diffusion assay demonstrating the biomedical application of the synthesized IL
<ol>
	<li>Pre-culture the fungal strain of Candida albicans (ATCC 90028)&#160;in yeast peptone dextrose (YPD) broth for nearly 16 h in a BOD shaker incubator at 37 &#176;C.</li>
	<li>Prepare YPD agar media by mixing 1% yeast extract, 2% peptone, 2% dextrose, and 1.5% agar in 1 L of double distilled water. Pour 25 mL of the freshly formed YPD agar media into a 90 mm Petri plate after autoclaving it for 15 min at 121 &#176;C. Leave the plates undisturbed to allow proper solidification of the media.</li>
	<li>Once the plate is completely solidified, spread around 100 &#181;L of the freshly prepared fungal inoculum homogeneously over the plate containing the media, using a glass spreader. Leave the plates undisturbed for 5-7 min in the laminar flow hood.</li>
	<li>Place a sterile circular paper disc of diameter of 5-6 mm in the middle of the same plate, using forceps.</li>
	<li>Add 50 &#181;L of 0.1 mM aqueous solution of the synthesized IL on the disc, gradually, with the help of a 20-200 &#181;L pipette.</li>
	<li>Refrigerate the plate for about 30 min to ensure proper diffusion of the IL into the agar. Place the plate in the BOD incubator pre-set at 37 &#176;C for 24 h.</li>
	<li>Measure the zone of inhibition (inclusive of the disc diameter) using a measuring scale and calculate the area under this zone as per equation 1. 
	Area = &#960;r2&#160; &#160; (1)</li>
</ol>

Synthesis of Quinoline-Based Ionic Liquids for Antimicrobial Applications

<ol>
	<li>Vekariya, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+ionic+liquids:+Applications+towards+catalytic+organic+transformations.">A review of ionic liquids: Applications towards catalytic organic transformations.</a> J Mol Liquids. 227 (3), 44-60 (2017).</li><li>Pena-Pereira, F., Kloskowski, A., Namie&#347;nik, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perspectives+on+the+replacement+of+harmful+organic+solvents+in+analytical+methodologies:+a+framework+toward+the+implementation+of+a+generation+of+eco-friendly+alternatives.">Perspectives on the replacement of harmful organic solvents in analytical methodologies: a framework toward the implementation of a generation of eco-friendly alternatives.</a> Green Chem. 17 (7), 3687-3705 (2015).</li><li>Anastas, P. T., Kirchhoff, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Origins,+current+status,+and+future+challenges+of+green+chemistry.">Origins, current status, and future challenges of green chemistry.</a> Account Chem Res. 35 (9), 686-694 (2002).</li><li>Cull, S. G., Holbrey, J. D., Vargas-Mora, V., Seddon, K. R., Lye, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room-temperature+ionic+liquids+as+replacements+for+organic+solvents+in+multiphase+bioprocess+operations.">Room-temperature ionic liquids as replacements for organic solvents in multiphase bioprocess operations.</a> Biotech Bioeng. 69 (2), 227-233 (2000).</li><li>Rooney, D. W., Jacquemin, J., Gardas, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermophysical+properties+of+ionic+liquids.">Thermophysical properties of ionic liquids.</a> Ionic Liquids. 3 (5), 185-212 (2010).</li><li>Qureshi, Z. S., Deshmukh, K. M., Bhanage, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applications+of+ionic+liquids+in+organic+synthesis+and+catalysis.">Applications of ionic liquids in organic synthesis and catalysis.</a> Clean Tech Environ Policy. 16 (8), 1487-1513 (2014).</li><li>Welton, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ionic+liquids+in+catalysis.">Ionic liquids in catalysis.</a> Coord Chem Rev. 248 (21-24), 2459-2477 (2004).</li><li>Singh, V. V., 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=Applications+of+ionic+liquids+in+electrochemical+sensors+and+biosensors.">Applications of ionic liquids in electrochemical sensors and biosensors.</a> Int J Electrochem. 2012 (9), 112-125 (2012).</li><li>Must, I., 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=Ionic+liquid-based+actuators+working+in+air:+The+effect+of+ambient+humidity.">Ionic liquid-based actuators working in air: The effect of ambient humidity.</a> Sens Actuat B: Chemical. 202 (3), 114-122 (2014).</li><li>Ray, A., Saruhan, B. <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+ionic+liquids+for+batteries+and+supercapacitors.">Application of ionic liquids for batteries and supercapacitors.</a> Materials. 14 (11), 2942 (2021).</li><li>Alashkar, 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=A+critical+review+on+the+use+of+ionic+liquids+in+proton+exchange+membrane+fuel+cells.">A critical review on the use of ionic liquids in proton exchange membrane fuel cells.</a> Membranes. 12 (2), 178 (2022).</li><li>Busetti, A., Crawford, R. J., Ivanova, E. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+and+antibiofilm+activities+of+1-alkylquinolinium+bromide+ionic+liquids.">Antimicrobial and antibiofilm activities of 1-alkylquinolinium bromide ionic liquids.</a> Green Chem. 12 (3), 420-425 (2010).</li><li>Sharma, K., Sharma, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+anti-biofilm+activity+and+the+artificial+chaperone+activity+of+quinoline-based+ionic+liquids.">In vitro anti-biofilm activity and the artificial chaperone activity of quinoline-based ionic liquids.</a> Colloids Surfaces B: Biointer. 235, 113773 (2024).</li><li>Qashou, 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=Antiproliferative+activities+of+lipophilic+fluoroquinolones-based+scaffold+against+a+panel+of+solid+and+liquid+cancer+cell+lines.">Antiproliferative activities of lipophilic fluoroquinolones-based scaffold against a panel of solid and liquid cancer cell lines.</a> Asian Paci J Cancer Prevent. 23 (5), 1529-1538 (2022).</li><li>Patel, H. 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+new+mannich+products+bearing+quinoline+nucleus+using+reusable+ionic+liquid+and+antitubercular+evaluation.">Synthesis of new mannich products bearing quinoline nucleus using reusable ionic liquid and antitubercular evaluation.</a> Green Sust Chem. 5 (4), 137-144 (2015).</li><li>Joshi, D. R., Adhikari, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+overview+on+common+organic+solvents+and+their+toxicity.">An overview on common organic solvents and their toxicity.</a> J Pharm Res Int. 28 (3), 1-18 (2019).</li><li>Sanchez, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Air+and+breath+analysis+for+the+assessment+of+exposure+to+solvent+emissions+in+university+chemistry+laboratories.">Air and breath analysis for the assessment of exposure to solvent emissions in university chemistry laboratories.</a> Atm Pollut Res. 10 (6), 1795-1802 (2019).</li><li>Sowmiah, S., Esperanca, J. M. S. S., Rebelo, L. P. N., Afonso, C. A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+chemical+stabilities+of+ionic+liquids.">On the chemical stabilities of ionic liquids.</a> Molecules. 14 (9), 3780-3813 (2009).</li><li>JoVE Science Education Database. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organic+Chemistry+II.">Organic Chemistry II.</a> Infrared Spectroscopy. , (2024).</li><li>Zhuo, Y., 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=Ionic+liquids+in+pharmaceutical+and+biomedical+applications:+A+review.">Ionic liquids in pharmaceutical and biomedical applications: A review.</a> Pharmaceutics. 16 (1), 151 (2024).</li><li>Hameed, 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=Process+for+the+preparation+of+quinoline-based+ionic+fluoride+salts+(QUFS).">Process for the preparation of quinoline-based ionic fluoride salts (QUFS).</a> US patent. , (2017).</li></ol>

The authors have nothing to disclose.

Lately, ILs have divulged various promising implementations in the field of biochemical sciences including protein refolding/ chaperone activity, drug delivery vehicles, and/or catalysts in several organic reactions. Their intriguing physicochemical properties, such as tunability, biocompatibility, solubility, sustainability, stability, etc., have made them potential candidates for the development of novel therapeutic agents20. The proposed research visualizes AMR as a matter of grave concern and ...

The monumental growth in the world population accounts for a tremendous increment in the consumption of a vast array of commodities over the past few years, including food, medicaments, as well as other crucial products for the sustenance of mortal organisms. This has invigorated the quest for novel chemical compounds with exceptionally specialized, ecologically sound, and beneficial properties worldwide. Ionic Liquids (ILs) have proved to be felicitous in this regard. The implication of these compounds in the scientific domain has bolstered new ventures in research in contemporary chemical technologies1. In contrast to the conventional approaches, the utilization of ILs not only facilitates progressive reaction conditions but also promotes a customized strategy to get to grips with various biochemical challenges related to experimental research and development2.
Typically, ILs are stable salts constituting cations (organic) and anions (inorganic), possessing a melting point below 100 &#176;C3. Abiding by the 12 principles of green chemistry, empirically, these are convincing substitutes to the customary organic solvents4. The astounding properties associated with the utilization of these compounds encompass great intrinsic conductivity, polarity, solvating tendency, thermal stability, non-volatility, acidity/basicity, hydrophilicity/ hydrophobicity, and tunability, making ILs best suited for experimental research5.
Apart from the expansive applications of various classes of ILs in modern organic synthesis6, catalysis7, and various electrochemical processes involving sensors8, actuators9, batteries10, and fuel cells11, over the past few years, this class of compounds has been given momentous recognition in the field of biomedicine in light of AMR. Current probations reveal that ILs based on imidazolium, pyridine, choline, and pyrrole are extremely effective as therapeutic agents owing to their high charge and hydrophobicity12. However, quinoline-based counterparts are still considered to be most potent against the pathogenic microbes12. Additional biomedical applications accompanying this class of ILs include artificial chaperone activity13, cytotoxicity against cancerous cells14 as well as an excellent drug-carrying capacity15.
Conventionally, the fabrication of ILs involves the utilization of highly toxic solvent mediums such as dichloromethane, benzene, carbon tetrachloride, dichloroethylene, etc.16, hindering the biocompatibility and elevating the toxicity of the compound, making them undesirable for biological use. Additionally, the use of harmful solvents in the reaction media not only slows down the reaction time but also increases the unintentional production of waste byproducts released into the environment17. Moreover, the dissolvent used in the reaction media also influences the pH of the final product; hence, its removal at the end of the reaction is vital, especially when the desired compound is intended to be used for protein-related biological systems. Hence, keeping away from the usage of such solvent is favorable in the realm of green chemistry.
In this study, we report the one-pot synthesis of a biocompatible and non-toxic13 IL, namely, 1-Hexadecylquinolin-1-ium bromide, using a greener route. The present strategy omits the utilization of a molecular solvent, leveraging the self-solvating ability of the IL formed within the reaction mixture, promoting high reaction efficiency and chemical yield. Menschutkin reaction18forms the basis of the&#160;current synthesis methodology. The purity of the synthesized compound is probed using NMR and IR spectroscopy. The pharmacokinetic profile of the compound and toxicity were investigated through the ADMET studies. Furthermore, the antimicrobial potential of the synthesized IL against the pathogenic Candida albicans strain has also been demonstrated in the study.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1-bromohexadecane</td>
			<td>Merck</td>
			<td>CAS no.112-82-3</td>
			<td>95% pure (as determined by HPLC analysis)</td>
		</tr>
		<tr>
			<td>Ethyl acetate</td>
			<td>Merck</td>
			<td>CAS no. 205-500-4</td>
			<td>95% pure (as determined by HPLC analysis)</td>
		</tr>
		<tr>
			<td>Nuclear Magnetic Resonance (NMR) spectrometer</td>
			<td>Jeol, Model: JNM-ECZ 400S</td>
			<td>Nil</td>
			<td>Nil</td>
		</tr>
		<tr>
			<td>Quinoline</td>
			<td>Merck</td>
			<td>CAS no.91-22-5</td>
			<td>95% pure (as determined by HPLC analysis)</td>
		</tr>
		<tr>
			<td>Toluene</td>
			<td>Merck</td>
			<td>CAS no. 108-88-3</td>
			<td>95% pure (as determined by HPLC analysis)</td>
		</tr>
	</tbody>
</table>

green synthesis of quinoline-based ionic liquid

The ever-growing menace of Antimicrobial Resistance (AMR) jeopardizes the potency of the prevailing antibiotics against the relentlessly sprouting infections spawned by bacteria, viruses, parasites as well as fungi, posing a great threat to human health and well-being. In this regard, several novel molecules have proved their mettle, with Ionic Liquids (ILs) being one of the most eco-friendly, non-volatile, and thermally stable alternatives to the existing antimicrobials, possessing high solvating potential as well as low vapor pressure. Moreover, the utilization of these entities in both stabilizing as well as destabilizing protein structures and enhancing enzymatic activity has further raised their potential in the biomedical industry. With this in view, we present the green synthesis and characterization of quinoline-based IL, owing to its immense antimicrobial potency, with low cytotoxicity and great artificial chaperone activity. Here, maneuvering the one-pot synthesis approach in solvent-free, greener reaction conditions not only ameliorated the reaction efficiency but also augmented the chemical yield. The purity of the synthesized IL was corroborated using 1H Nuclear Magnetic Resonance (NMR), 13C NMR, and Infrared (IR) spectroscopy. The biological potential of the synthesized compound is further validated by analyzing its Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) properties and authenticated using disc diffusion assay.

Figure 2&#160;represents the reaction scheme of the Menschutkin reaction involved in bringing about the synthesis process. 1-Hexadecylquinolin-1-ium bromide, thus synthesized, was characterized using NMR and IR spectroscopy. The oily product so acquired is expected to exhibit 1H NMR (400 MHz, CDCl3) at &#948; 9.34 (d, 1H), 8.21 (d, 1H), 7.80 (t, 1H), 7.30-7.35 (m, 3H), 7.20 (d, 1H), 5.00 (t, 2H), 2.00 (p,2H), 1.30-1.35 (m, 26H), 1 (t, 3H), as demonstrated in <strong cla...

Author Spotlight: Advancing Antimicrobial Resistance Research with Innovative Approaches and Synthetic Compounds

In the present work, we elucidate the green synthesis of quinoline-based Ionic Liquid (IL), namely, 1-Hexadecylquinolin-1-ium bromide {[C16quin]Br} by mixing quinoline with an excess of 1-Bromohexadecane, along with its detailed characterization using Nuclear Magnetic Resonance and Infrared spectroscopic measurements.

Green Synthesis of Quinoline-Based Ionic Liquid

The ever-growing menace of Antimicrobial Resistance (AMR) jeopardizes the potency of the prevailing antibiotics against the relentlessly sprouting ...

green-synthesis-of-quinoline-based-ionic-liquid

Research

JoVE Journal

Chemistry

1.7K Views.  University of Delhi. In the present work, we elucidate the green synthesis of quinoline-based Ionic Liquid (IL), namely, 1-Hexadecylquinolin-1-ium bromide {[C16quin]Br} by mixing quinoline with an excess of 1-Bromohexadecane, along with its detailed characterization using Nuclear Magnetic Resonance and Infrared spectroscopic measurements. 

Video: Author Spotlight: Advancing Antimicrobial Resistance Research with Innovative Approaches and Synthetic Compounds

Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. The most common techniques utilized are imaging modalities such as Magnetic Resonance Imaging (MRI), Positron Emission Topography (PET), and Computed Topography (CT) and are optimal for understanding the physical structure of the disease but can only be performed once every four to six weeks due to the use of imaging agents and overall cost. With this in mind, the development of &#8220;point of care&#8221; techniques, such as biosensors, which evaluate the stage of disease and/or efficacy of treatment in the clinician&#8217;s office and do so in a timely manner, would revolutionize treatment protocols.1 As a means to exploring ferrocene based biosensors for the detection of biologically relevant molecules2, methods were developed to produce ferrocene-biotin bio-conjugates described herein. This report will focus on a biotin-ferrocene-cysteine system that can be immobilized on a gold surface.

The synthesis of asymmetric species of ferrocene is challenging using solution techniques. This report focuses on the methods carried out to produce a ferrocene-biotin bioconjugate using facile and clean reactions accomplished via solid-phase synthesis. Incorporation of a thiolate moiety is shown to impart the ability for immobilization on gold surfaces.

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. ...

Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form catalytically active N-Heterocyclic Carbenes (NHCs). Here we have used ILs as precatalysts in the addition of &#945;,&#946;-unsaturated aldehydes to chalcones to form 1,6-ketoesters, incorporating an anti-diphenyl moiety in a highly stereoselective fashion. The reaction has a broad substrate scope and several functional groups and heteroaromatics can be integrated into the ketoester backbone in generally good yields with maintained stereoselectivity. The reaction protocol is robust and scalable. The starting materials are inexpensive and the products can be obtained after simple filtration, avoiding solvent-demanding chromatography. Furthermore, the IL can be recycled up to 5 times without any loss of reactivity. Moreover, the 1,6-ketoester end product is a potent gelator in several hydrocarbon based solvents. The method enables rapid access to and evaluation of a new class of low molecular weight gelators (LMWGs) from recyclable and inexpensive starting materials.

Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents.

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form ...

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials.

A novel methodology is presented to synthesize and program main-chain liquid-crystalline elastomers using commercially available starting monomers. A wide range of thermomechanical properties was tailored by adjusting the amount of crosslinker, while the actuation performance was dependent on the amount of applied strain during programming.

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline ...

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag+) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid crystals (ILCs). Taking advantages of the high specificity of XB for haloperfluorocarbons and the ability of anions to act as XB-acceptors, we obtained supramolecular complexes based on 1-alkyl-3-methylimidazolium iodides and iodoperfluorocarbons, overcoming the well-known immiscibility between hydrocarbons (HCs) and perfluorocarbons (PFCs). The high directionality of the XB combined with the fluorophobic effect, allowed us to obtain enantiotropic liquid crystals where a rigid, non-aromatic, XB supramolecular anion acts as mesogenic core.
X-ray structure analysis of the complex between 1-ethyl-3-methylimidazolium iodide and iodoperfluorooctane showed the presence of a layered structure, which is a manifestation of the well-known tendency to segregation of perfluoroalkyl chains. This is consistent with the observation of smectic mesophases. Moreover, all the reported complexes melt below 100 &#176;C, and most are mesomorphic even at room temperature, despite that the starting materials were non-mesomorphic in nature.
The supramolecular strategy reported here provides new design principles for mesogen design allowing a totally new class of functional materials.

A protocol for the synthesis of a new type of mesogens, based on the halogen-bonded supramolecular anion [CnF2n+1-I&#183;&#183;&#183;I&#183;&#183;&#183;I-CnF2n+1]&#8722;, is reported.

Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

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 ...

Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid

The accurate molecular simulation prediction of vibrational spectra, and other structural, energetic and spectral characteristics, of photo-active metal-oxide surfaces in contact with light-absorbing dyes is an ongoing thorny and elusive challenge in physical chemistry. With this in mind, a molecular-dynamics (MD) simulation were performed by using optimized empirical potentials for a well-representative and prototypical dye-sensitized solar cell (DSC) solvated by a widely-studied room temperature ionic liquid (RTIL), in the guise of a [bmim]+[NTf2]- RTIL solvating an N719-sensitizing dye adsorbed onto 101 anatase-titania. In doing so, important insights were gleaned into how using a RTIL as the electrolytic hole acceptor modulates the dynamical and vibrational properties of a N719 dye, estimating the spectra for the DSC photo-active interface via Fourier transformation of mass-weighted velocity autocorrelation functions from MD. The acquired vibrational spectra were compared with the experiment spectra and those sampled from ab initio molecular dynamics (AIMD); in particular, various empirical-potential spectra generated from MD provide insight into how partial-charge charge parameterization of the ionic liquid affects vibrational spectra prediction. In any event, careful fitting of empirical force-field models has been shown to be an effective tool in handling DSC vibrational properties, when validated by AIMD and an experiment.

A dye-sensitized solar cell was solvated by RTILs; using optimized empirical potentials, a molecular dynamics simulation was applied to compute vibrational properties. The obtained vibrational spectra were compared with experiment and ab initio molecular dynamics; various empirical potential spectra show how partial-charge charge parameterization of the ionic liquid affects vibrational spectra prediction.