3-thiopheneacetic Acid Research Articles

The Luminescent Conjugated Oligothiophene h-FTAA Attenuates the Toxicity of Different Aβ Species.

The prevailing opinion is that prefibrillar β-amyloid (Aβ) species, rather than end-stage amyloid fibrils, cause neuronal dysfunction in Alzheimer’s disease, although the mechanisms behind Aβ neurotoxicity remain to be elucidated. Luminescent conjugated oligothiophenes (LCOs) exhibit spectral properties upon binding to amyloid proteins and have previously been reported to change the toxicity of Aβ1–42 and prion protein. In a previous study, we showed that an LCO, pentamer formyl thiophene acetic acid (p-FTAA), changed the toxicity of Aβ1–42. Here we investigated whether an LCO, heptamer formyl thiophene acetic acid (h-FTAA), could change the toxicity of Aβ1–42 by comparing its behavior with that of p-FTAA. Moreover, we investigated the effects on toxicity when Aβ with the Arctic mutation (AβArc) was aggregated with both LCOs. Cell viability assays on SH-SY5Y neuroblastoma cells demonstrated that h-FTAA has a stronger impact on Aβ1–42 toxicity than does p-FTAA. Interestingly, h-FTAA, but not p-FTAA, rescued the AβArc-mediated toxicity. Aggregation kinetics and binding assay experiments with Aβ1–42 and AβArc when aggregated with both LCOs showed that h-FTAA and p-FTAA either interact with different species or affect the aggregation in different ways. In conclusion, h-FTAA protects against Aβ1–42 and AβArc toxicity, thus showing h-FTAA to be a useful tool for improving our understanding of the process of Aβ aggregation linked to cytotoxicity.

Development of Polythiophene–Tripeptide Covalent Conjugates Showing Excellent Structure-Dependent Photophysical and Photocurrent Properties

Presently, conducting polymer–peptide conjugates have drawn great interest for their interesting optoelectronic and photophysical properties. To understand the structural dependence of the conjugates on their properties, we have covalently coupled poly(3-thiophene acetic acid) (P3TAA) with a C-protected tripeptide, H2N-F-F-V-OMe (TPEP), to produce their conjugate PTCP-I. A carboxylic acid-deprotected tripeptide polythiophene conjugate (PTCP-II) is also produced by alkaline hydrolysis of PTCP-I to delineate any difference in properties due to the change in molecular structure. The stretching frequencies for −NH– and >C═O groups of PTCP-II are 11 and 26 cm–1 lower than those of PTCP-I, indicating better intermolecular hydrogen bonding interactions in the former. This alters the seaweed morphology of PTCP-I to a sheet morphology for PTCP-II. The blue shift of the π–π* absorption band of polythiophene with gradually increasing the PTCP-I concentration is attributed to the H-type aggregation in DMF solution, but in the solid state, this peak shows a 17 nm red shift from its solution state for better electron delocalization for closer proximity of molecules. The UV–Vis peak of PTCP-II shows a lower blue shift than that of PTCP-I in DMF, attributed to the uncoiled polythiophene chains of the former. In DMF solution, interestingly, both PTCP-I and PTCP-II conjugates exhibit aggregation-induced emission (AIE), showing maxima at 0.08 mg/mL and then aggregation-induced quenching (AIQ) with further increasing its concentration. PTCP-I and PTCP-II exhibit dc conductivities of 0.04 and 0.55 μS cm–1, respectively, at 30 °C, and the higher value for PTCP-II is due to its lower band gap (1.91 eV) compared to that of PTCP-I (2.14 eV). The current (I)–voltage (V) plot of both conjugates exhibits semiconducting properties, which are higher for PTCP-II for its lower band gap. The photocurrent behavior of the conjugates indicates that the on–off response in the PTCP-II system is significantly higher than that in PTCP-I due to the unfolded polymer chain of the former, as the photogenerated electrons and holes can move more freely there. Impedance spectra of both the conjugates show single semicircles for the Nyquist plots, and the charge transfer resistance of PTCP-II is 4.4 times lower than that of PTCP-I but the capacitance value is 27 times higher, arising from the more extended chain configuration of the former, signifying structural importance on the optoelectronic and photocurrent properties of the polymer–peptide conjugates.

Two-dimensional MoS2-based impedimetric electronic tongue for the discrimination of endocrine disrupting chemicals using machine learning

• E-tongue was built for multi-target prediction of endocrine-disrupting chemicals. • XGBoost machine learning model has shown high accuracy. • Feature selection using information visualization technique enhanced the prediction accuracy. In this paper, we report on machine learning to analyze the capacitance spectra obtained with an electronic tongue (e-tongue) and discriminate three endocrine-disrupting chemicals (EDC): bisphenol A, estrone, and 17- β -estradiol, and their mixtures. The e-tongue comprised seven sensing units made with interdigitated gold electrodes coated with layer-by-layer films of poly( o -methoxy aniline), poly(3-thiophene acetic acid), and molybdenum disulfide (MoS 2 ). The Multilayer Perceptron (MLP), Random Forest, and Extreme Gradient Boosting (XGBoost) models were applied for multi-target regression to predict the concentration of individual contaminants and their mixtures. These machine learning models were evaluated according to the root mean square error (RMSE) values. The best performance was achieved with XGBoost for which RMSE ranged from 0.19 to 3.37 for individual contaminants, from 0.12 to 0.25 for the mixtures, and from 0.34 to 3.46 for the entire dataset. The high performance was only possible with a multi-target regression strategy, including a feature selection procedure. In the latter, the data were plotted with the parallel coordinate technique, and the silhouette coefficient was calculated, which is a quantitative measure of the ability to distinguish similar samples in a dataset. The usefulness of the machine learning methods is demonstrated by noting that the data from mixtures of EDCs could not be distinguished using multidimensional projections. Also significant is that this combination of machine learning and information visualization methodology is entirely generic; it may be applied to analyze data from e-tongues and other sensing and biosensing devices in prediction tasks as demanding as in the discrimination of mixtures of EDCs at concentrations below nmol L −1 .

Rapid, sensitive and label-free detection of pathogenic bacteria using a bacteria-imprinted conducting polymer film-based electrochemical sensor

The rapid and sensitive detection of pathogenic bacteria is very important for timely prevention and treatment of foodborne disease. Here, a bacteria-imprinted conductive poly(3-thiopheneacetic acid) (BICP) film-based impedimetric sensor was developed for the rapid, sensitive and label-free detection of staphylococcus aureus (S. aureus). The BICP film preparation was very convenient and eco-friendly, which was in situ deposited on gold electrode surface without the use of toxic organic solvents and cross-linkers. The process of imprinting and recognition were characterized by electrochemical technique and scanning electron microscope. The BICP had a novel structure without cocci-shaped cavities formed in the poly(3-thiopheneacetic acid) (PTAA) matrices. To obtain the optimal sensing performance, a set of factors affecting the imprinting and recognition were investigated. Under the optimized conditions, an extremely rapid recognition within 10 min, a very low limit of detection (LOD) of 2 CFU/mL, and wide linear range from 10 to 108 CFU/mL were achieved by the BICP film-based impedimetric sensor. The sensor also demonstrated high selectivity, and good universality and repeatability. Furthermore, the feasibility of its application has also been demonstrated in the analysis of real milk samples. This sensor offered a simple and universal method for rapid, sensitive, and selective detection of pathogenic bacteria, which could hold great potentials in fields like food safety.

Simple electrochemical detection of Listeria monocytogenes based on a surface-imprinted polymer-modified electrode.

Listeria monocytogenes (LM) is a foodborne pathogen, and it can pose a risk of serious diseases to the human health. Hence, the development of an effective method for the detection of LM is very important. In this study, by selecting LM as the template and 3-thiopheneacetic acid as the functional monomer, an LM-imprinted polymer (LIP)-based sensor was proposed for the first time to detect LM by electropolymerizing TPA on the glassy carbon electrode (GCE) surface in the presence of LM. After the removal of the LM template from the electrode surface, the obtained sensor was denoted as LIP/GCE, which could effectively recognize and capture LM cells. By using [Fe(CN)6]4-/3- as the probe, its peak current at LIP/GCE could be restricted when the LM cells were captured into the imprinted cavity of LIP/GCE, and the current value decreased with an increase in the LM concentration. Serious conditions were optimized for achieving highly sensitive detection, and a low detection limit (6 CFU mL-1) coupled with a wide linear range (10 to 106 CFU mL-1) was obtained for LM. Finally, the inter-electrode reproducibility, stability, selectivity, and applicability of LIP/GCE were also investigated, and the obtained results were acceptable.

IMPEDIMETRIC CLAVMO PEPTIDE-BASED SENSOR DIFFERENTIATES PLOIDY OF CANDIDA SPECIES

Yeast biotechnologies are a cornerstone to modern lifestyle in all spheres of society, as their products are essential for the economy and industrial activities. The life cycle of many yeasts such as Candida alternates between diplophase and haplophase. Both ploidies can exist as stable cultures; however, it has been shown that wild haploid yeast efficiently cross in poor environments, whereas wild diploid species hybridize predominantly in rich nutrient surroundings. Some Candida species have had their ploidy engineered to produce various important biomolecules useful to the detergent, food, pharmaceutical and other industries. Several works show that MALDI-TOF MS has become an ideal platform for ploidy analysis. Recent reports have shown that antimicrobial peptides (AMP) present enhanced hydrophobic interaction towards cell membranes. In this work, the authors explored a modified AMP named Clavanin A (CLAVMO) as an unprecedented bioreceptor capable of differentiating the molecular composition of the cell wall of Candida spp. A thin film of poly(3-thiophene acetic acid) (PTAA) was electropolymerized to avail the covalent immobilization of amino-functionalized titanium dioxide nanoparticles (TiO2NPs) whose electrochemical properties are excellent to provide a discernable redox response. Electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM) were used to characterize the biosensor assembly and the biorecognition process. Additionally, MALDI-TOF was employed to confirm ploidy of Candida strains used in this work. Our results suggest that TiO2NPs_CLAVMO biosensor is a suitable biological probe that can be used to detect and differentiate Candida species based on their ploidy. For instance, C. Albicans and C. tropicalis, which are close related species known for being diploid presented higher impedimetric response than haploid species C.krusei and C. glabrata. The proposed biosensor stands out as a useful alternative for highly sensitive differentiation of Candida yeast cells, without the intricacies of MALDI-TOF sample preparation. The biodetection event and its electrochemical evaluation took less than 20 min to perform. The platform showed stability for over a week, a linear detection range between 101-106 CFU mL-1 and limits of detection (LODs) between 2 and 3 CFU mL-1.

Novel Hemocompatible Imine Compounds as Alternatives for Antimicrobial Therapy in Pharmaceutical Application

The aim of this study was to synthesize, characterize, and evaluate neoteric imine compounds for antimicrobial activity and hemocompatibility. Four compounds were synthesized using 3-thiophene carboxaldehyde, ethanol, amine, and acetic acid. The compounds were characterized using nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD). A solubility study was conducted with various solvents and surfactants at 40 °C. An in vitro antimicrobial assay was performed against bacterial and fungal strains to determine the zone of inhibition and minimum inhibitory concentrations. Finally, an in vitro hemolysis study was conducted using rat erythrocytes. The structure of the compounds was confirmed by NMR, FTIR corroborated their functional group attributes, DSC determined their enthalpies of fusion and fusion temperatures, and PXRD confirmed their crystalline nature. These compounds were water-insoluble but soluble in chloroform, with a maximum solubility of ~80 mg/mL. The antimicrobial assay suggested that two of the products exerted potent activities against C. albicans and several bacterial strains. Finally, hemolysis analysis excluded the possibility of hemolysis at the assessed concentrations. In conclusion, two of the novel imine compounds showed promise as antimicrobial agents to control local and systemic microbial infections in a suitable dosage form.

CuO-catalyzed conversion of arylacetic acids into aromatic nitriles with K4Fe(CN)6 as the nitrogen source

Readily available CuO was demonstrated to be effective as the catalyst for the conversion of arylacetic acids to aromatic nitriles with non-toxic and inexpensive K4Fe(CN)6 as the nitrogen source via the complete cleavage of the CN triple bond. The present method allowed a series of arylacetic acids including phenylacetic acids, naphthaleneacetic acids, 2-thiopheneacetic acid and 2-furanacetic acid to be converted into the targeted products in low to high yields.

Early detection of prion protein aggregation with a fluorescent pentameric oligothiophene probe using spectral confocal microscopy.

Misfolding of the prion protein (PrP) and templating of its pathological conformation onto cognate proteins causes a number of lethal disorders of central nervous system in humans and animals, such as Creutzfeldt-Jacob disease, chronic wasting disease and bovine spongiform encephalopathy. Structural rearrangement of PrPC into PrPSc promotes aggregation of misfolded proteins into β-sheet-rich fibrils, which can be visualized by conformationally sensitive fluorescent probes. Early detection of prion misfolding and deposition might provide useful insights into its pathophysiology. Pentameric formyl thiophene acetic acid (pFTAA) is a novel amyloid probe that was shown to sensitively detect various misfolded proteins, including PrP. Here, we compared sensitivity of pFTAA staining and spectral microscopy with conventional methods of prion detection in mouse brains infected with mouse-adapted 22L prions. pFTAA bound to prion deposits in mouse brain sections exhibited a red-shifted fluorescence emission spectrum, which quantitatively increased with disease progression. Small prion deposits were detected as early as 50days post-inoculation, well before appearance of clinical signs. Moreover, we detected significant spectral shifts in the greater brain parenchyma as early as 25 days post-inoculation, rivaling the most sensitive conventional method (real-time quaking-induced conversion). These results showcase the potential of pFTAA staining combined with spectral imaging for screening of prion-infected tissue. Not only does this method have comparable sensitivity to established techniques, it is faster and technically simpler. Finally, this readout provides valuable information about the spatial distribution of prion aggregates across tissue in the earliest stages of infection, potentially providing valuable pathophysiological insight into prion transmission.

Prominent microglial inclusions in transgenic mouse models of \u03b1-synucleinopathy that are distinct from neuronal lesions

Alpha-synucleinopathies are a group of progressive neurodegenerative disorders, characterized by intracellular deposits of aggregated α-synuclein (αS). The clinical heterogeneity of these diseases is thought to be attributed to conformers (or strains) of αS but the contribution of inclusions in various cell types is unclear. The aim of the present work was to study αS conformers among different transgenic (TG) mouse models of α-synucleinopathies. To this end, four different TG mouse models were studied (Prnp-h[A53T]αS; Thy1-h[A53T]αS; Thy1-h[A30P]αS; Thy1-mαS) that overexpress human or murine αS and differed in their age-of-symptom onset and subsequent disease progression. Postmortem analysis of end-stage brains revealed robust neuronal αS pathology as evidenced by accumulation of αS serine 129 (p-αS) phosphorylation in the brainstem of all four TG mouse lines. Overall appearance of the pathology was similar and only modest differences were observed among additionally affected brain regions. To study αS conformers in these mice, we used pentameric formyl thiophene acetic acid (pFTAA), a fluorescent dye with amyloid conformation-dependent spectral properties. Unexpectedly, besides the neuronal αS pathology, we also found abundant pFTAA-positive inclusions in microglia of all four TG mouse lines. These microglial inclusions were also positive for Thioflavin S and showed immunoreactivity with antibodies recognizing the N-terminus of αS, but were largely p-αS-negative. In all four lines, spectral pFTAA analysis revealed conformational differences between microglia and neuronal inclusions but not among the different mouse models. Concomitant with neuronal lesions, microglial inclusions were already present at presymptomatic stages and could also be induced by seeded αS aggregation. Although nature and significance of microglial inclusions for human α-synucleinopathies remain to be clarified, the previously overlooked abundance of microglial inclusions in TG mouse models of α-synucleinopathy bears importance for mechanistic and preclinical-translational studies.

A label-free immunosensor for sensitive detection of RACK 1 cancer biomarker based on conjugated polymer modified ITO electrode

A new flexible biosensor based on conjugated polymer functionalized indium tin oxide (ITO) sheet was fabricated for Receptor for Activated C Kinase 1 (RACK 1) determination. Poly(3-thiophene acetic acid) (P(Thi-Ac)) was used as an immobilization matrix for construction of RACK 1 immunosensor. This polymer had a great number of carboxyl groups on its end site and these carboxyl ends provided anchoring points to the anti-RACK 1 antibodies. Anti-RACK 1 antibodies were covalently attached on the ITO electrode and recognized the RACK 1 antigens. Electrochemical characterizations were made by employing electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. Additionally, single frequency impedance method (SFI) was applied to follow the specific biointeraction between antibody and antigen. As a result of specific biointeraction, the designed immunosensor exhibited a wide linear detection range between 0.01 pg/mL and 2 pg/mL RACK 1 with a detection limit of 3.1 fg/mL. Scanning electron microscopy and atomic force microscopy analyses were employed for electrode surface morphology investigation. The designed RACK 1 biosensor had good repeatability (5.73 %, RSD), excellent reproducibility (2.5 %, RSD), long storage-stability and reusable property. In addition, the fabricated RACK 1 biosensor was applied to determine RACK 1 concentration in human serums and the recovery was ranging from 98.79%–100.22%. This work illustrated a new tool to construct a sensitive and low-cost disposable biosensor for applications in clinical monitoring.

Determination of HOMO and LUMO Level of Polythiophene, Poly(3-Thiophene Acetic Acid), Polypyrrole and Chlorophyll via Cyclic Voltammetry Method

Cyclic voltammetry can be used to investigate the chemical reactivity of species ion via oxidation and reduction process. The purpose of this study is to determine the level energy of high occupied molecule orbital (HOMO) and low unoccupied molecule orbital (LUMO) in polythiophene (PT), Poly (3-thiophene acetic acid) (P3TAA), polypyrrole (PPY) and chlorophyll (Chlo) through oxidation and reduction of molecular ions by cyclic voltammetry method. PT, P3TAA, PPY and Chlo solutions were prepared in a solvent of acetonitrile at the concentration range of 10-2 to 10-4 M. The current-voltage measurements for these solutions are performed using cyclic voltammetry method on input voltage from -2.0 V to 2.0 V. The working electrode used is indium tin oxide (ITO). The result of voltammogram is showed that the activity of PT species were produced three oxidation and one reduction processes. The formal reduction potential, Eo¢ is 0.83 (positive) meaning that oxidation process was dominant. So that the reaction of PT species was exhibited irreversible electrochemical behavior. The reaction of P3TAA species was exhibited reversible electrochemical behavior, where the range value of oxidation, DEpa and reduction, DEpc were in range of 0.825 V to 1.120 V and -0.230 V to 0.131 V respectively. PYY species reaction was exhibited irreversible electrochemical behavior where two oxidation states occur within -0.145 V to -0.202 V and 0.870 V to 1.63 V respectively. The species activity of Chlo was exhibited irreversible electrochemical behavior where only the oxidation process was obviously appeared at range of 0.80 V to 0.95 V. The LUMO energy levels of PT, P3TAA PPY and Chlo were 5.84 eV, 5.34 eV, 1.10 eV and 3.85 eV respectively, while HOMO energy levels of PT, P3TAA PPY and Chlo were 4.61 eV, 4.25eV, 3.70 eV and 5.93 eV. The average value of energy gap of PT, P3TAA, PPY and Chlo were 1.23 eV, 1.08 eV, 2.23 eV and 1.10 eV respectively.

A Resistive Biosensor for the Detection of LC3 Protein in Autophagy

Resistive sensing techniques have recently emerged as a powerful tool to sensitively detect proteins of interest. However, detecting intracellular proteins present in cell-derived lysates remains largely unexplored. Here, a resistive sensing technique was utilized to develop a biosensor for the detection of the autophagy-related LC3 protein using three different resistive transducers. Microfiber-, paper- and carbon nanofiber-based transducers were compared to determine optimal sensitivity. The microfiber- and paper-based transducers utilized a conductive poly-pyrrole, co-polymerized with carboxylic acid functional 3-thiopheneacetic acid, allowing for effective cross-linking between the conductive coated substrates and LC3 antibodies using glutaraldehyde as the cross-linking agent. Anti-LC3 antibodies were immobilized on the highly conductive carbon nanofiber using adsorbed 1-pyrenebutyric acid and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as the cross-linking agent. A resistive sensor capable of mediating the protein-antibody binding and accurately measuring a change in conductivity of the transducers was designed and manufactured. The portable sensor was integrated with a computer to generate and display measured results via a user-friendly interface. The various transducing elements were added to the sensor where LC3 detection took place. All three transducers proved effective at detecting LC3 protein in the solution buffer and were capable of distinguishing between different concentrations of LC3 protein in a highly sensitive manner. The results highlight how the unique combination of transducer- and system design, in combination with resistive sensing enables the rapid, robust and accurate detection of the LC3 protein, reporting on a critical biological process, here autophagy.

Short Communication: Antioxidant and antibacterial properties of tree fern Cyathea contaminans

Abstract. Faizal A, Taufik I, Rchman AF, Azar AWP. 2020. Short Communication: Antioxidant and antibacterial properties of tree fern Cyathea contaminans. Biodiversitas 21: 2201-2205. Cyathea contaminans (Wall. ex Hook) Copel is a tree fern used in traditional practices as herbal remedies to treat different kinds of diseases. To explore its further medicinal uses, we designed a study to determine the antioxidant and antibacterial activities of polar and non-polar extracts of this fern. The fern leaves (mature fronds), young fronds, and hairs were collected from Tangkuban Perahu Nature Park, West Java, Indonesia, and were extracted by methanol 80% or n-hexane. Antioxidant activity was evaluated by DPPH (1,1-diphenyl-2-picrylhydrazyl) assay, whereas antibacterial activity was measured by growth inhibition of Escherichia coli and Staphylococcus aureus. Results showed that methanol extract from mature leaves (fronds) exhibits weak to very strong antioxidant activities (IC50 37.13-225.19 µg/mL), whilst hairs and young fronds showed weak activities, i.e. IC50 179.50-255.49 µg/mL and IC50 544.27->2000 µg/mL, respectively. Hexane fraction from fronds was active against E. coli and S. aureus (43.92% and 46.8%), and from hairs against E. coli (48.1%) in concentration of 250 µg/mL. Gas Chromatography-Mass Spectrometry (GC-MS) analysis indicated that active compounds from fronds extract were dominated by 2H-tetrazole, 5-(thiophen-2yl) methyl (14,29 %), 2-thiophene acetic acid, 2-methyl phenyl ester (14,54%), and phenol, 2,6-bis(1,1-dimethyl ethyl)-4-methyl (10.54%). This study concluded that mature leaves (fronds) of C. contaminans is the potential to be used as antioxidant and antibacterial agents.

Computational study of 3-thiophene acetic acid: Molecular docking, electronic and intermolecular interactions investigations

The present work undertakes the structural and electronic properties of 3-thiophene acetic acid (abbreviated as 3-TAA) monomer and dimer. DFT calculations were performed using B3LYP functional in combination with the aug-cc-pVTZ basis set. The optimized structural parameters were found to be in a good agreement with experimental molecular geometry. The stability of the crystal packing was ensured by OH⋯O, C-H⋯O and CH⋯S intermolecular interactions. All the Non covalent interactions were deeply studied in terms of their topological parameters, Hirshfeld surface (HS) analysis and reduced density gradient (RDG) analysis. The electronic properties of the investigated compound have been performed using time dependent density functional theory (TD-DFT) and discussed through its correspondant HOMO, LUMO and excitation energy values. Likewise, the reactivity of 3-TAA was discussed in terms of several thermodynamic parameters. In addition, the molecular electrostatic potential (MEP) surface has been performed and discussed in terms of color distribution. In addition, the natural bond orbital (NBO) analysis was used to investigate the electronic charge transfer into the molecule. Harmine, Clorgyline, Isatin, zonisamide and our title compound including are known with their competitive inhibitory activity on Human monoamine oxidase, commonly named MAO A and B. This enzyme is a critical enzyme in the degradative deamination of biogenic amines throughout the body. Thus, molecular docking behaviors of 3-TAA are computed and compared to the results found for Harmine, Clorgyline, Isatin, zonisamide ligands.

Effect of interchain interactions on the optical characteristics of polythiophene derivatives

ABSTRACT The characterisation of electrochemically synthesised poly(3-hexylthiophene) (P3HT), poly(3-thiopheneacetic acid) (P3TAA) and poly(3-hexylthiophene-co-3-thiopheneacetic acid) (P3HT-co-P3TAA) in solution and as cast film is reported. The effect of intermolecular interactions via aggregate forming in solvents and in bulk films is analysed with FTIR, UV/Vis and fluorescence spectroscopy. The results exhibit that P3TAA has a significantly reduced mean π conjugation length of the thiophene backbone compared to P3HT. Structural defects due to hydrogen bonding in acetic acid derivatives disturb effective interchain electronic interactions, indicating that after excitation emissive excitons localise on molecule segments with shorter mean conjugation lengths.

Quantum Mechanics/Molecular Mechanics Density Functional Theory Simulations of the Optical Properties Fingerprinting the Ligand-Binding of Pentameric Formyl Thiophene Acetic Acid in Amyloid-β(1-42).

The binding pocket proposed by König [ Chem. Commun. 2018 , 54 , 3030 - 3033 ] for the biomarker pentameric formyl thiophene acetic acid (p-FTAA) in the fibrillar structure of amyloid-β(1-42) has been put to the test by the comparison of theoretical and experimental optical absorption and fluorescence spectra obtained in a water environment and inside the protein scaffold. The optical absorption/emission properties of this luminescent conjugated oligothiophene were studied by means of classical force field molecular dynamics simulations to account for the sampling of configuration space in conjunction with polarizable embedding time-dependent density functional theory calculations of spectra. The nuclear motions of residues in the β-sheet were found to be modest, and the time dependence of embedding parameters was shown to be negligible so that a time-independent parameter set could be derived and used for all 300 snapshots considered in the spectrum averaging. In regard to linear absorption spectra, the calculated red shift due to protein binding for the dominant S1 ← S0 transition in p-FTAA was found to be equal to 23 nm (0.17 eV), which is in excellent agreement with the corresponding experimental result of 18 nm and taken as corroborating evidence for having correctly identified the binding pocket of p-FTAA in the amyloid. The underlying mechanisms for the calculated red shift were disentangled, and it is shown that some 20 nm (0.15 eV) of the total 23 nm (0.17 eV) is associated with increased planarity of p-FTAA in the binding pocket, whereas a mere 3 nm (0.02 eV) is associated with changes in the environment. In regard to emission spectra, we demonstrate that intersystem crossing from the excited S1 state to the triplet manifold of states is a less likely event for p-FTAA in the binding pocket as compared to in the aqueous solution, and we thereby partly explain the much higher quantum yield of fluorescence for the more rigid p-FTAA in the binding pocket. Two-photon absorption in p-FTAA is shown to predominantly occur to an overall symmetric excited state and be more than twice as strong for the biomarker in the binding pocket as compared to in water. The corresponding red shift, on the other hand, is very small. Earlier experimental two-photon fluorescence imaging using p-FTAA is shown not to target the dominant two-photon state, and ways to reach a higher image quality (lower signal-to-noise ratio) are proposed in terms of tuning the laser wavelength toward the region of 600 nm or the synthesis of asymmetric ligands with S1 states that are both one- and two-photon allowed.

Optimal strategy based on radiation chemistry for facile and direct synthesis of poly(3-thiophene acetic acid) polymers in water and dichloromethane

γ-Induced polymerization was used as a novel method to easily synthesize nanostructured PTAA polymers in water and dichloromethane.

A mechanistic study of 1,3,5-trisubstituted-1,2,3-triazoles by Ab initio method

The mechanism of synthesis of 1,3,5-trisubstituted-1,2,4-triazoles from 3-thiopheneacetic acetic acid, 4-pyridine formamidine, and tri-fluoro ethyl hydrazine has been first investigated with B3LYP/6-311++G** method in this article. According to the potential energy profile, it can be predicted that the course of the reaction consists of six elementary reactions. The 3-thiopheneacetic acetic acid and 4-pyridine formamidine form first an intermediate product through a dehydration reaction; the intermediate product further combines with hydrogen ion to form a positive ions; the positive ion reacts with three fluorine ethyl hydrazines by a dehydration reaction to form another positive ions; then, it followed by two isomerization reactions, the final reaction with the acetate ion (Ac−) produces the final product. The research results reveal the laws of synthesis reaction of 1,3,5-trisubstituted-1,2,4-triazoles by the carboxylic acids, amidines, hydrazines, and their derivatives on theoretical level. These studies provide the systematic theoretical basis to design and synthesize new 1,3,5-trisubstituted-1,2,4-triazoles.

Influence of Poly(Vinylidene fluoride) on photovoltaic performance of interfacially engineered band gap modulated P3TAA-co-P3HT perovskite solar cell at ambient condition

Recently, mixing of foreign polymers with perovskite increases light absorption yielding a large increase of power conversion efficiency (PCE) and also increasing longevity of perovskite solar cells (PSCs). The previous studies are limited at dry or at very low humid conditions. Here, for practical use, we report a new series of poly(vinylidene fluoride) (PVDF)-perovskite (MAPbI3) hybrid solar cells made from different PVDF concentrations e.g. 0.0, 0.25, 0.5, 1.0, 2.5, 5.0 mg/ml, and are designated as H1, H2, H3, H4, H5, and H6, respectively. The average grain size, measured from SEM images of MAPbI3 (312 ± 91 nm) has decreased with increasing PVDF concentration showing a minimum (215 ± 43 nm) for H5 sample. UV–Vis absorption spectra show the highest absorption for H5 sample for all the wavelengths. The intensities and width of X-ray diffraction peaks increase in the hybrids (H3 and H5) from pristine perovskite indicating increase of crystallinity and crystalline size. We have used an interfacially engineered, band gap modulated poly(3-thiophene acetic acid)–co-poly(3-hexyl thiohene) P3TTA - co - P3HT, with 43 mol% P3TAA content as hole transporting material (HTM) and TiO2 as electron transporting material (ETM) to fabricate the cell. The PCE, measured on illumination with a light of one sun at ambient condition (humidity 75–85%, temperature 30 °C), is 12% for H5 PSC, highest reported so far, and it is 20% higher from pristine PSC. The incident photon to current conversion efficiency (IPCE) data exhibit strong absorption in the broad range 300–800 nm showing a maximum IPCE value of 84%. Impedance spectral data indicate that lifetime of photo-generated charges are highest (48.4 m s) explaining the highest PCE value for H5-PSC compared to other hybrids. The longevity of the H5-PSC is significantly (54%) higher than PSC made with pristine perovskite measured and stored under identical ambient condition.