Progress in conducting/semiconducting and redox-active oligomers and polymers of arylamines

Recent advances in synthesis, characterization and application of the selected conducting/semiconducting and redox-active oligomers and polymers of arylamines are reviewed. A brief historical background of the selected topics is given. The overview of the preparation, structure and properties of polyaniline, substituted polyanilines, especially those obtained by the oxidative polymerization of p-substituted anilines, poly(1-aminonaphthalene) and its derivatives, carbocyclic and heterocyclic polyaryldiamines such as poly(p-phenylenediamine) and polydiaminoacridines, is presented. The mechanism of formation of polyaniline nanostructures is discussed. Recent approaches to the preparation of one-dimensional polyaniline nanostructures are concisely reviewed, with special attention paid to the template-free falling-pH method. Current and potential future applications of oligo/polyarylamines are briefly discussed. [Projekat Ministarstva nauke Republike Srbije, br. OI 172043

Nanostructured materials for sensing Pb(II) and Cd(II) ions: Manganese oxohydroxide versus carbonized polyanilines?

Nanostructured materials including three different carbonized polyanilines and manganese oxyhydroxide were prepared and evaluated as electrode materials for sensing of lead and cadmium ions in aqueous media. Anodic stripping voltammetry results indicated that all prepared materials could be successfully used for determination of these two heavy metal ions. Carbonized polyaniline-based electrodes have higher signal and lower limits of detection (10-7 М) compared to manganese oxyhydroxide-based electrode. Among the three studied carbonized polyanilines, the one that was derived from polyaniline precursor produced in the presence of 3,5-dinitrosalicyclic acid showed the highest electrocatalytic activity towards the lead and cadmium oxidation. [Projekat Ministarstva nauke Republike Srbije, br. OI172043 i br. III45014

Oksidativna polimerizacija anilina u prisustvu fenolnih kiselina

Aniline was oxidized with ammonium peroxydisulfate (APS) in aqueous solutions of various phenolic acids: 5-sulfosalicylic acid (SSA), 3,5-dinitrosalicylic acid (DNSA) and gallic acid (GA). Polymerizations were performed at the constant molar ratios [acid]/[aniline] = 0.5 and [APS]/ /[aniline] = 1.25. The conductivity of synthesized polyaniline (PANI) is affected by the dopant anion type and decreases in order: PANI-SSA > > PANI-DNSA > PANI-GA, the last polymer being nonconducting. This decrease is in accordance with the increase of initial pH value of the reaction mixture. The differences in molecular structure of synthesized PANI have been revealed by FTIR spectroscopy. FTIR spectra of PANI-SSA and PANI-DNSA show typical features of PANI conductive emeraldine salt segments. On the contrary, FTIR spectrum of PANI-GA shows absence of bands typical for conducting PANI polaronic lattice, and indicates the higher oxidation state of this polymer than that of emeraldine, the presence of substituted phenazines as constitutional units, as well as significant content of monosubstituted benzene rings which reflects low polymerization degree and/or pronounced chain branching. The strong hydrogen bonding between GA and PANI can obstruct propagation of oligoanilines and formation of longer conducting PANI chains.Polianilin (PANI) sintetisan je oksidacijom anilina u vodenim rastvorima fenolnih kiselina: 5-sulfosalicilne (SSA), 3,5-dinitrosalicilne (DNSA) i galne kiseline (GA), koristeći amonijum-peroksidisulfat (APS) kao oksidaciono sredstvo. Sinteze su urađene pri konstantnim polaznim molskim odnosima kiselina/anilin i APS/anilin. Utvrđeno je da sa porastom jačine fenolne kiseline raste električna provodljivost dobijenih polianilina. PANI-GA je neprovodan, PANI-DNSA pokazuje provodljivost ~10-3 S cm-1, dok je provodljivost PANI-SSA ~10-1 S cm-1. Na osnovu uporedne analize FTIR spektara protonovanih i deprotonovanih formi ovih polimera diskutovane su razlike u njihovoj molekulskoj strukturi

Sinteza nanostrukturiranog provodnog polianilina u prisustvu 5-sulfosalicilne kiseline

Oxidative polymerizations of aniline with ammonium peroxydisulfate in aqueous solution of 5-sulfosalicylic acid (SSA), were performed at the constant molar ratio [oxidant]/[monomer] = 1.25, by using various initial molar ratios of SSA to aniline. It was shown that the ratio [SSA]/[aniline] has a crucial influence on the molecular structure, morphology, and conductivity of synthesized polyaniline5-sulfosalicylate (PANI-SSA), as well as on the yield and temperature profile i.e. the mechanism of polymerization process. The yield of PANI-SSA was 80 - 86% for [SSA]/[aniline] ratios in the range 0.25-1.0. Granular PANI-SSA was obtained by the oxidative polymerization of in situ formed anilinium 5-sulfosalicylate ([SSA]/[aniline] = 1.0). The initial induction period was followed by the rapid exothermic polymerization of aniline during the oxidation of anilinium 5-sulfosalicylate with peroxydisulfate. Nanostructured PANI-SSA was synthesized by the oxidation of the mixture of dianilinium 5-sulfosalicylate and aniline ([SSA]/[aniline] = 0.25), which proceeds in two exothermic phases well separated with an athermal period. The presence of nanocylinders (nanorods, possibly nanotubes), with the average diameter of 95-250 nm and the length of 0.5-1.0 μm has been revealed by scanning electron microscopy. It was concluded that PANI nanocylinders are formed when reaction solution has the initial pH > 3.5. Electroconductivity of synthesized polyanilines was in the range 0.01-0.17 S cm-1, and it increases with increasing molar ratio of SSA to aniline. Molecular structure of synthesized polyanilines was investigated by FTIR spectroscopy. Besides the characteristic bands of standard PANI in emeraldine form (benzenoid, quinonoid, and semiquinonoid units), the band attributable to substituted phenazine structural units was observed at -1415 cm-1 in the FTIR spectrum of nanostructured PANI-SSA sample.Elektroprovodni nanostrukturirani polianilin sintetisan je oksidacijom, anilina u vodenom rastvoru 5-sulfosalicilne kiseline, koristeći amonijum peroksidisulfat kao oksidaciono sredstvo. Utvrđeno je da početni molski odnos 5-sulfosalicilne kiseline i anilina ima odlučujući uticaj na temperaturni profil i prinos reakcije polimerizacije, kao i na molekulsku strukturu, morfologiju i elektroprovodljivost dobijenog polianilina. Prisustvo nanoštapića prosečnog prečnika 95-250 nm i dužine 0,5-1,0 μm utvrđeno je skenirajućom elektronskom mikroskopijom. Gelpropusnom hromatografijom određene su vrednosti molame mase usrednjene po masi i indeksa polidisperznosti. Elektroprovodljivost sintetisanih uzoraka polianilina je 0,01-0,17 S cm-1. FTIR spektroskopijom ispitana je molekulska struktura sintetisanih polianilina

Entrepreneurial Factors Influencing Recovery from Covid-19: A Country-Level Analysis

This study examines the impact of entrepreneurship ecosystem factors on the recovery of entrepreneurship from the COVID-19 pandemic and offers valuable insights to drive growth. By analyzing the Serbian dataset from the Global Entrepreneurship Monitor National Expert Survey in 2022, the study employs linear regression analysis to investigate the relationship between Entrepreneurial Framework Conditions and post-pandemic recovery. Data were collected through interviews with 40 experts representing the government, academia, and industry. The National Entrepreneurship Context Index score for Serbia\u27s entrepreneurial environment quality in 2022 is 4.6 which positions Serbia in the middle of the continuum of included country scores. The results of the analysis have shown that Market openness (β = .474; p < .01) and Achieving the UN Sustainable Economic Development Goals (β = .460; p < .01) have a direct positive impact on the recovery of entrepreneurs from the consequences of COVID-19. The limitations of the study are related to the demographics of the sample, self-reported data, geographic scope, focusing only on the Republic of Serbia, cross-sectional design that does not capture the dynamic and evolving nature of the recovery process. Given these limitations, future work could incorporate a more diverse sample to enhance the generalizability of the findings.This research provides important insights and policy recommendations to leverage entrepreneurial practices for economic recovery following the impact of the COVID-19 pandemic

Electrochemical Sensing of Cadmium and Lead Ions in Water by MOF-5/PANI Composites

For the first time, composites of metal-organic framework MOF-5 and conjugated polymer polyaniline (PANI), (MOF-5/PANI), prepared using PANI in its conducting (emeraldine salt, ES) or nonconducting form (emeraldine base, EB) at various MOF-5 and PANI mass ratios, were evaluated as electrode materials for the electrochemical detection of cadmium (Cd2+) and lead (Pb2+) ions in aqueous solutions. Testing of individual components of composites, PANI-ES, PANI-EB, and MOF-5, was also performed for comparison. Materials are characterized by Raman spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS), and their electrochemical behavior was discussed in terms of their zeta potential, structural, morphology, and textural properties. All examined composites showed high electrocatalytic activity for the oxidation of Cd and Pb to Cd2+ and Pb2+, respectively. The MOF/EB-1 composite (71.0 wt.% MOF-5) gave the highest oxidation currents during both individual and simultaneous detection of two heavy metal ions. Current densities recorded with MOF/EB-1 were also higher than those of its individual components, reflecting the synergistic effect where MOF-5 offers high surface area for two heavy metals adsorption and PANI offers a network for electron transfer during metals’ subsequent oxidation. Limits of detection using MOF/EB-1 electrode for Cd2+ and Pb2+ sensing were found to be as low as 0.077 ppm and 0.033 ppm, respectively. Moreover, the well-defined and intense peaks of Cd oxidation to Cd2+ and somewhat lower peaks of Pb oxidation to Pb2+ were observed at voltammograms obtained for the Danube River as a real sample with no pretreatment, which implies that herein tested MOF-5/PANI electrodes could be used as electrochemical sensors for the detection of heavy metal ions in the real water samples

Synthesis and characterization of conducting polyaniline nanotubes in the presence of colloidal TiO2 nanoparticles

Conducting polyaniline nanotubes were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in water, in the presence of colloidal TiO2 nanoparticles of an average diameter ~5 nm. Polyaniline-TiO2 nanocomposite has been characterized by the electrical conductivity measurements, thermogravimetric analysis, FTIR spectroscopy, scanning and transmission electron microscopies. The electrical conductivity of synthesized nanocomposite was 1.1 × 10–3 S cm–1, slightly higher than that of pure polyaniline prepared under the same conditions. Polyaniline nanotubes have an outer diameter of 45–230 nm nm, an inner diameter of 15–130 nm, and a length extending from 0.5 to 2.0 μm.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Struktura i stereohemija poli-(1-naftilamina) elektrohemijski sintetisanog u neutralnom acetonitrilnom rastvoru

Poly-(1-naphthylamine) films were synthesized potentiodinamically and potentiostatically from 1-naphthylamine in neutral acetonitrile medium using a platinum electrode. These polymer films were investigated by infrared spectroscopy. Contrary to earlier published results neglecting the stereochemistry of the poly-(1-naphthylamine), we predict on the basis of quantum stereochemical analysis of the possible structural subunits of the polymer, that the ordinary N–C(4) coupled product is not predominant in the polymer because it is far removed from the expected planarity. Based on the results of IR investigations and semiempirical quantum chemical calculations, it is proposed that the polymer products are formed via mixed N–C(4), N–C(5) and N–C(7) coupling routes. The heats of formation of the oxidized 1-naphthylamine dimers and hexamers were calculated.Poli-(1-naftilaminski) filmovi sintetisani su potenciostatski i potenciodinamički iz neutralnog acetonitrilnog rastvora 1-naftilamina na platinskoj elektrodi. Ovi polimerni filmovi ispitivani su IR spektroskopijom. Za razliku od ranije publikovanih rezultata koji su zanemarivali stereohemiju poli-1(-naftilamina), u ovom radu se predviđa na osnovu kvantne stereohemijske analize mogućih strukturnih jedinica polimera da uobičajeni N–C(4) kuplovani produkt nije predominantan u polimeru, jer njegova struktura nije planarna. Na osnovu rezultata IR ispitivanja i semiempirijskih kvantno-hemijskih proračuna mi pretpostavljeno je da se polimerni produkti formiraju kombinovanim N–C(4), N–C(5) i N–C(7) načinima vezivanja 1-naftilamina. U ovom radu su takođe izračunate toplote nastajanja oksidovanih dimera i heksamera 1-naftilamina

Assessment of sugar beet root yield by ammi analysis

Sugar beet cultivars have different responses in various environments, such as different locations, years, mineral nutrition treatments or the combination of these factors, due to genotype x environment interaction. Additive main effect and multiplicative interaction (AMMI) is one of the most commonly used multivariate methods for analysis and visualization of genotype x environment interaction data. The main goals of the present study were to (i) investigate the application of AMMI method in the analysis of genotype x fertilizer interaction in sugar beet, (ii) to assess genotype x fertilizer interaction, and (iii) to identify sugar beet cultivars with the most stable response and high yield performance across different mineral nutrition treatments. The trial with eight sugar beet cultivars was conducted in two successive growing seasons at Rimski sancevi, Serbia. The different levels of nitrogen, phosphorous and potassium fertilizers (0, 50, 100 and 150 kg ha(-1)) and their combinations represented specific environments for testing genotype x fertilizer interaction. Results from the analysis of variance indicated that the fertilizer treatment, cultivars, and their interaction significantly affected root yield variation in both seasons. Results from our study suggest that AMMI model with two and three first IPCA axes were recommended in 2014 and 2015, respectively. According to AMMI 1 and AMMI 2 biplot, E14 and E15 were high yielding and among the most stable treatments in both years. Among high yielding genotypes in 2014, G4 and G8 stand out as the most stable, while in the following year G3 had the lowest interaction score. AMMI analysis enabled identification of specific associations between cultivars and different mineral nutrition treatments, which was important for adjustment of fertilizer management for each cultivar in order to achieve high root yield with decreased and more rational fertilizer doses

Genotype x environment interaction of some traits in sunflower (helianthus annuus l.) Lines

The evaluation of genotype x environment interaction (GXE) is an important component of the selection process in multi-environment trials. The objective of this study was to analyze the GXE interaction for seed yield (SY), germination rate (GR), thousand seed weight (TSW) and protein content (PC) of 18 sunflower parental lines through the application of AMMI analysis, as well as to identify suitable sunflower parental lines with both high performance and high stability. Highly significant differences for SY, GR, TSW and PC were found for main effects (genotypes, years). For all investigated traits GXE interaction was also highly significant, suggesting a different response of genotypes across testing environments. Highest SY was shown by genotypes G12, G14 and G17. Most stable lines for seed yield were Gl, G2, G18 and G17. High stability in terms of GR showed the genotypes G3, G11 and G15, with average values higher than the general average. In the three-year experiment environment E3 was most stable for GR. Genotypes G2, G4, G5, G6 and G7 were stable for TSW. Similar average values and stability for TSW showed E2 and E3. The lines with the most stable reaction in the examined environmental conditions for PC were G7 and G10. The most stable environment for PC was E3