Microwave-Assisted One-Pot Telescoped Synthesis of 2-Amino-1,3-thiazoles, Selenazoles, Imidazo[1,2-a]pyridines, and Other Heterocycles from Alcohols.

Primary and secondary alcohols have been converted into 2-amino-1,3-thiazoles under microwave irradiation, employing trichloroisocyanuric acid (TCCA) as a dual oxidant and chlorine source, TEMPO as a co-oxidant, and thiourea. Secondary alcohols underwent a single-stage, one-pot conversion process, while primary alcohols required a two-stage, one-pot procedure. Both transformations were completed within minutes (25-45 min). The versatility of this protocol extends to the synthesis of other heterocycles, including 1,3-selenazoles, 2-aminoimidazoles, imidazo[1,2-a]pyridines, quinoxalines, and hydrazino thiazoles by replacing thiourea with the appropriate surrogates.

Simple and cost-effective pH and T sensors from top to bottom: New chemical probes based on sonogel-carbon transducers for plasma analyses.

The present work introduces two novel approaches to fabricate simple and cost-effective pH and temperature probes. Sinusoidal voltage methodologies were employed to electrodeposit polyaniline (PANI) at different growth times (10-20 min) on the surface of an affordable Sonogel-Carbon electrode to conform a robust pH sensor. The presence of PANI and its phases were corroborated by electrochemical means. The sensibility, reversibility and selectivity of the produced sensor were very adequate to apply it in physiological samples. In this regard, the proposed sensor was evaluated in artificial blood serum as well as untreated plasma samples obtaining outstanding results in comparison with a gold reference technique (error <2 %). In addition, a new composite sonogel material, intrinsically modified with multiwalled carbon nanotubes, was attached on top of an electrode couple to one-step fabricate a new temperature probe, relating resistance of the probe with the surroundings temperature. In this case, an optical microscopy characterization was performed to study the sturdiness of the layer. Remarkably, suitable results in terms of sensitivity and selectivity were obtained. The probes were assessed in artificial and untreated plasma samples as well, with the corresponding validation step (error <1 %) by using a commercial temperature probe.

Incorporation of carbon black into a sonogel matrix: improving antifouling properties of a conducting polymer ceramic nanocomposite.

A new electrochemical sensor device has been developed through the modification of a polyaniline-silicon oxide network with carbon black (CB). Enhanced electrical conductivity and antifouling properties have been achieved due to the integration of this cheap nanomaterial into the bulk of the sensor. The structure of the developed material was characterized using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy techniques. Cyclic voltammetry was used to characterize electrochemically the Sonogel-Carbon/Carbon Black-PANI (SNG-C/CB-PANI) sensor device. In addition, differential pulse voltammetry was employed to evaluate the analytical response of the sensor towards sundry chlorophenols, common environmental hazards in aqueous ecosystems. The modified sensor material showed excellent antifouling properties, which led to a better electroanalytical performance than the one displayed with the bare sensor. Notably, a sensitivity of 5.48 × 103 µA mM-1 cm-2 and a limit of detection of 0.83 µM were obtained in the determination of 4-chloro-3-methylphenol (PCMC) at a working potential of 0.78 V (vs. 3 M Ag/AgCl/KCl), along with proficient values of reproducibility and repeatability (relative standard deviation < 3%). Finally, the analysis of PCMC was carried out in multiple validated water samples using the synthesized SNG-C/CB-PANI sensor device, obtaining excellent results of recovery values (97-104%). The synergetic effect of polyaniline and carbon black leads to novel antifouling and electrocatalytic effects that improve the applicability of this sensor in sample analysis versus complex conventional devices.

Ultrasound-promoted synthesis of a copper-iron-based catalyst for the microwave-assisted acyloxylation of 1,4-dioxane and cyclohexene.

A copper-iron-based catalyst has been prepared by a low-temperature co-precipitation and sonication method. The use of high-energy ultrasound reduces the time required for the preparation process from one workweek to one day with respect to the catalysts obtained by conventional coprecipitation and thermal treatment methods. The resulting material has been characterized at compositional, textural, structural, and chemical levels by ICP-AES, BET, SEM-EDS, XRD, TEM, and FTIR among other techniques. The material shows catalytic activity in the acyloxylation reaction of 1,4-dioxane and cyclohexene under microwave irradiation. In parallel with the optimized catalyst synthesis, the use of microwaves allowed for a substantial improvement in the outcome of the reaction in terms of cleanliness, yield, and time.

What Is Left for Real-Life Lactate Monitoring? Current Advances in Electrochemical Lactate (Bio)Sensors for Agrifood and Biomedical Applications.

Monitoring of lactate is spreading from the evident clinical environment, where its role as a biomarker is notorious, to the agrifood ambit as well. In the former, lactate concentration can serve as a useful indicator of several diseases (e.g., tumour development and lactic acidosis) and a relevant value in sports performance for athletes, among others. In the latter, the spotlight is placed on the food control, bringing to the table meaningful information such as decaying product detection and stress monitoring of species. No matter what purpose is involved, electrochemical (bio)sensors stand as a solid and suitable choice. However, for the time being, this statement seems to be true only for discrete measurements. The reality exposes that real and continuous lactate monitoring is still a troublesome goal. In this review, a critical overview of electrochemical lactate (bio)sensors for clinical and agrifood situations is performed. Additionally, the transduction possibilities and different sensor designs approaches are also discussed. The main aim is to reflect the current state of the art and to indicate relevant advances (and bottlenecks) to keep in mind for further development and the final achievement of this highly worthy objective.

Polyaniline Nanofibers-Embedded Gold Nanoparticles Obtained by Template-Free Procedure with Immobilization Prospects.

In this work, template-free nanostructured conducting polymers (nCPs)-embedded gold nanoparticles (AuNPs) from aniline, thiophene and 3,4-ethylenedioxythiophene have been prepared via a one-pot sonochemical method. The synthesis of the nanocomposite (nCPs-AuNPs) was achieved in a short period of time (5-10 min), by applying high-energy ultrasound to an aqueous mixture of a CP precursor monomer and KAuCl4, in the presence of LiClO4 as dopant. The synthesis process is simpler, greener and faster in comparison to other procedures reported in the literature. Remarkably, bulk quantities of doped polyaniline PANI-AuNPs nanofibers were obtained. Subsequently, they were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR), as well as by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). PANI-AuNPs nanofibers were also employed as immobilization matrix for a benchmark enzyme, glucose oxidase (GOX). Finally, glucose was determined in real samples of white and red wines by using the so-obtained GOX-PANI-AuNPs/Sonogel-Carbon biosensor, providing outstanding recoveries (99.54%). This work may offer important insights into the synthesis of nanostructured conducting polymers and also stimulates the exploration of the applications of these nanocomposites, especially in research fields such as (bio)sensors, catalysis and composite materials.

Copper-Catalyzed Microwave-Expedited Oxyphosphorylation of Alkynes with Diethyl Phosphite and t-Butyl Hydroperoxide Synthesis of Densely Functionalized Phosphonylated Indenones.

Treatment of alkynes with diethyl phosphite and t-butyl hydroperoxide in the presence of [Cu(MeCN)4]BF4 under microwave irradiation produced the oxyphosphorylation of the triple bond, giving rise to the corresponding ß-ketophosphonates in moderate-to-good yields. When the triple bond was conjugated to a carbonyl group bearing an aromatic ring, it led to the cyclization of the resulting ketone intermediate, producing eventually different phosphonylated indenones.

E-Tongues/Noses Based on Conducting Polymers and Composite Materials: Expanding the Possibilities in Complex Analytical Sensing.

Conducting polymers (CPs) are extensively studied due to their high versatility and electrical properties, as well as their high environmental stability. Based on the above, their applications as electronic devices are promoted and constitute an interesting matter of research. This review summarizes their application in common electronic devices and their implementation in electronic tongues and noses systems (E-tongues and E-noses, respectively). The monitoring of diverse factors with these devices by multivariate calibration methods for different applications is also included. Lastly, a critical discussion about the enclosed analytical potential of several conducting polymer-based devices in electronic systems reported in literature will be offered.