We report the synthesis of a new conjugated polymer bearing crown ether moieties, poly[(N(1-aza-[18]crown-6)carbamido)thiophene-2,5-diyl-alt-1,4-phenylene] (BG2). In water, BG2 forms a dispersion with a slightly cloudy appearance. We have studied the effect of adding surfactants, with different polar head groups, on these polymer-polymer aggregates. Special attention is given to the system with the anionic surfactant, sodium dodecyl sulfate (SDS). The combination of photophysical techniques with electrical conductivity, NMR (1H, 13C, and 27Na), DFT calculations, molecular dynamics simulations, and small-angle neutron scattering (SANS) provides a detailed picture on the behavior of the SDS/BG2 system in aqueous solution and in thin films. NMR, electric conductivity, and DFT results suggest that hydrophilic interactions occur between the polar headgroup of the surfactant (OSO3- Na+) and the aza-[18]-crown-6 moiety. DFT calculations confirmed the capability of BG2 to form stable complexes with the Na+ cations, where the cation can be either inside the azacrown cavity or sandwiched between the cavity and the polymer chain, which seem to determine the position of the surfactant hydrocarbon chain and, therefore, be responsible for the disruption of the BG2 aggregates and subsequent increase in the photoluminescence quantum yields. SANS measurements, made with hydrogenated and deuterated SDS in D2O, clearly show how micron-sized aggregates of BG2 are broken down by SDS and then how BG2 becomes preferentially incorporated within joint colloidal particles of BG2 and SDS with increasing [SDS]/[BG2] molar ratio.

O Professor António Jorge Andrade Gouveia (1905-2002) foi uma personalidade multifacetada envolvida em diferentes actividades e contribuições para a investigação e ensino da química, ciência e história da ciência e governo universitário, como evocado pelos autores do presente volume. A comunidade química reconhece a sua contribuição para a química, mas é a faceta de Reitor da Universidade de Coimbra que é mais conhecida do público. Esta obra traça um retrato vivo e profundo da sua vida e herança científica.

The International Union of Pure and Applied Chemistry and Solvay announce the winners of the 2021 IUPAC-Solvay International Award for Young Chemists, presented for the best Ph.D. theses in the chemical sciences, as described in 1000-word essays.

Following previous studies on the complexation in aqueous solutions of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the trivalent metal ions, Al(III) and Ga(III) and various other metal ions, using multinuclear NMR, DFT calculations, UV-vis absorption and luminescence techniques, we have extended our studies on 8-HQS complexation to the trivalent metal ion In(III). The study combines the high sensitivity of luminescence techniques and the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to obtain a complete understanding of the complexation between the In3+ metal ion and 8-HQS, and how this influences the luminescence behaviour. A full speciation study has been performed and, as has been reported for the complexes of 8-hydroxyquinoline (8-HQ), the dominant complexes of 8-HQS with In(III) show marked differences in the complexation behaviour when compared with the equivalent complexes with the other group 13 cations Al(III) and Ga(III). While all three complexes have a 1 : 3 (metal : ligand) stoichiometry, those with Al(III) and Ga(III) show a mer-geometry of the ligands around the metal centre, whereas the fac-geometry is observed for the complexes with In(III). On binding to metal ions, 8-HQS shows a marked increase in the intensity of the fluorescence emission band compared to that of the virtually non-luminescent free ligand. However, the increase for In(III) is less pronounced than with Al(III) or Ga(III). These observations have important implications for the application of the complexes in sensing, light emitting devices (e.g. OLEDs), or as electron transport layers in photovoltaics for solar energy conversion. Furthermore, surfactant complexation is known to improve the fluorescence intensity in metal complexes with 8-HQS, by inhibiting the ligand exchange, as we have reported for complexes of HQS with Al(III) and Ga(III). Accordingly, in view of the development of applications in either sensing or optoelectronics, our interest also includes the study of HQS complexes of In(III) in the presence of cationic surfactants, in comparison with previous results with Al(III) and Ga(III).

Amino-acyl-quinoxalinone yellow dyes are cyclised analogues of the yellow azomethine dyes developed for, and still used in, silver halide colour photography. Unlike image azomethine dyes, which are rapidly deactivated in their excited states by torsion about the azomethine bond, amino-acyl-quinoxalinone dyes have an interesting photophysics because torsion is not possible due to their cyclised structure. We report results from studies on singlet and triplet state properties, and singlet oxygen yields, of the yellow dye, 7-diethylamino-3-(2,2-dimethyl-propionyl)-5-methyl-1-phenyl-1H-quinoxalin-2-one, in polar and nonpolar solvents. The dye photophysics is characterised by a weak fluorescence, with a solvent dependent emission yield (ΦF ≈ 0.002–0.004), and short singlet state lifetime (τexpt ≈ 20–50 ps), both increasing by a factor of ≈2 in going from polar acetonitrile to non-polar dioxane as solvent. DFT ZINDO calculations show a transition involving significant electron transfer from the diethyl-amino group into the carbonyl region of the molecule. In solution, in the presence of oxygen, the triplet state decays almost exclusively by oxygen quenching, and singlet oxygen is produced in high yield (Φ∆ ≈ 0.5–0.55). The triplet state absorbs across the 450–750 nm region with maxima around 480 and 650 nm, and moderate molar absorption coefficients (ca. 6000–8000 M−1 cm−1). In a glass at 77 K, triplet decay gives a red phosphorescence, with λmax ≈ 640–650 nm, and a  ≈ 0.25 s lifetime. If singlet oxygen yields are a good indication of triplet yields, then internal conversion and intersystem crossing occur with roughly equal efficiency.

The large-scale use of pesticides is one of the main causes of the dramatic degradation of our environment. Pesticides such as imidacloprid (IMID) have been linked to declines in bee health and toxicity to other beneficial insects. They pose a threat to human health due to their persistence in the environment and accumulation in the food chain. Therefore, it is essential to test possible environmentally-friendly solutions for their elimination. The present study evaluates the efficiency of microalgae Nannochloropsis sp. for the removal of IMID from synthetic wastewater. The influence of aeration, light, and the presence of UV radiation on the degradation of IMID were factors considered in the study. A rapid RP-HPLC method was developed and validated for the analysis and quantification of IMID in the context of bioremediation with microalgae. Nannochloropsis sp. removed 4.39 µg mL−1 from an initial content of 9.59 µg mL−1 (reaching approximately 50%) of IMID in the first 20 h. This study demonstrated that the removal of IMID by the marine microalgae Nannochloropsis sp. is both effective and light-dependent.

IUPAC created a Award for Young Chemists in 2000 to recognise and reward outstanding research scientists at the beginning of their careers. Since 2014, this has been generously sponsored by Solvay, and five IUPACSOLVAY International Awards for Young Chemists are given each year. The success of this initiative can be seen by since 2014 many of the awardees going on to highly successful careers [1]. Award winners are chosen from among dozens of applicants, based on detailed analysis of a 1000-word essay on the candidate’s Ph. D. work by a Jury, comprised of members of the IUPAC Bureau and a Senior Science Advisor from Solvay. The Jury has a wide range of expertise in chemistry, and makes efforts to ensure inclusivity with respect to gender and geographical distribution in their selection of the winners. It was chaired in 2018 and 2019 by Professor Natalia Tarasova, IUPAC Past President. The winners each received a cash prize of USD 1000 and travel expenses to the 47th IUPAC World Chemistry Congress, 7–12 July 2019, in Paris, France. They were also invited to present a poster at the IUPAC Congress describing their award-winning work and to submit a short critical review to be published in Pure and Applied Chemistry. The awards were presented during the Opening Ceremony of the Congress. There was a good global representation of candidates, with 45 applications from 15 countries in 2018, and 30 application from 14 countries in 2019. After consideration of the quality, originality and importance of the presentations, the Jury decided unanimously to award the 2018 prizes to the following five essays: – Eduardo Bolea-Fernandez, Ghent University, Belgium, “Method development for ultra-trace elemental and isotopic analysis using tandem ICP-mass spectrometry (ICP-MS/MS)”. – Dane W. deQuilettes, University of Washington, USA, “Probing Local Heterogeneity in the Optoelectronic Properties of Organic-Inorganic Perovskites Using Fluorescence Microscopy”. – Palas Roy, Tata Institute of Fundamental Research, Mumbai, India, “Probing the Fate of Excitons in Organic Semiconductors”. – Monika Stolar, University of Calgary, Canada, “Development of Phosphoryl-Bridged Viologens Toward Functional Materials”. – Chi Zhang, Massachusetts Institute of Technology, USA, “Cysteine Arylation”.

The Chemical Weapons Convention aims to eliminate the production and use of all chemical warfare agents. It is an international treaty, with 193 participating nation states, and entered into force in 1997. It prohibits the development, production, stockpiling or use of chemical weapons. The Organisation for the Prohibition of Chemical Weapons (OPCW) is responsible for the implementation of their elimination within the terms of the Convention [1]. It is based in The Hague (The Netherlands), and has a staff of around 400 people, with the transdisciplinary expertise, necessary for ensuring that the goals of the Chemical Weapons Convention are achieved. The OPCW was awarded the 2013 Nobel Prize for Peace “For its extensive efforts to eliminate chemical weapons”. The International Union of Pure and Applied Chemistry (IUPAC) shares many of the goals of the OPCW, and the two organizations have collaborated extensively through workshops, articles and special issues in the IUPAC publications Pure and Applied Chemistry and Chemistry International, sharing of scientific and technical expertise, and organization of educational and outreach activities. In November 2019, IUPAC received the 2019 OPCW-The Hague Award for Outstanding Contributions to a World Free of Chemical Weapons, jointly with Dr Robert Mikulak, the former Permanent Representative of the United States to the OPCW, and Mr Cheng Tang, expert on chemical demilitarisation from the People’s Republic of China [2]. This highly prestigious award represents recognition of IUPAC’s “strong and lasting cooperation with OPCW to serve humankind through contributing knowledge and advances in the science and technology of chemistry at the worldwide level, helping to achieve the goals of CWC, as well as providing OPCW with the tools and materials for informing society about the responsible uses of chemistry.” Pure and Applied Chemistry is happy to celebrate the OPCW-The Hague Award for Outstanding Contributions to a World Free of Chemical Weapons through a virtual issue of the Journal, containing articles associated with the collaboration with OPCW from IUPAC publications.

We report a synthetic strategy to combine different moieties in a single structure using cyanuric chloride (2,4,6-trichlorotriazine) as a starting platform for preparing potential bioimaging agents. This reacted with macrocycles of the porphyrin family and DOTA type metal chelators through mono-, di- and tri- substitution of its chlorine atoms by appropriate nucleophiles, controlling the stepwise by temperature, to produce a system that opens the potential for biomedicinal applications. Porphyrins were chosen as one of the sensing arms, based on their rich structural chemistry, and excellent photophysical properties, while DO3A was used since it can form a versatile aminopropionate functionalized metal ion chelator. All new compounds were fully characterized, both spectroscopically and photophysically.

A rapid reverse phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the simultaneous quantification of paracetamol, ibuprofen, olanzapine, simvastatin and simvastatin acid in the context of microalgae bioremediation. The method was validated according to the guidelines of the US Food and Drug Administration (FDA), the International Conference on Harmonization (ICH), and Eurachem with respect to system suitability, linearity, accuracy, precision, recovery, limits of detection and quantification, ruggedness, selectivity and specificity. The estimated limits of detection and quantification were, respectively, 0.03 and 0.10 µg mL−1 for paracetamol, 0.03 and 0.09 µg mL−1 for ibuprofen, 0.04 and 0.13 µg mL−1 for olanzapine, 0.27 and 0.83 µg mL−1 for simvastantin, and 0.05 and 0.14 µg mL−1 for simvastantin acid. The inter-day and intra-day precision results were within the acceptance limit of relative standard deviation (%RSD) of less than 2, and the percentage recovery was found to be within the required limits of 80–110%. The developed method is rapid, linear, precise, robust and accurate, and has been successfully applied to the determination of the above common pharmaceutical products during microalgae bioremediation.

The photophysical properties of Eu^3+ and Tb^3+ complexes of DOTAGA and DO3A-monoamide conjugates of the Pittsburgh compound B (PiB) chromophore, prepared using linkers of different lengths and flexibilities, and which form stable negatively charged (LnL1), and uncharged (LnL2) complexes, respectively, were studied as potential probes for optical detection of amyloid aggregates. The phenylbenzothiazole (PiB) moiety absorbs light at wavelengths longer than 330 nm with a high molar absorption coefficient in both probes, and acts as an antenna in these systems. The presence of the luminescent Ln^3+ ion quenches the excited states of PiB through an energy transfer process from the triplet state of PiB to the metal centre, and structured emission is seen from Eu^3+ and Tb^3+. The luminescence study indicates the presence of a ^5D_4 → T_1 back transfer process in the Tb^3+ complexes. It also provides insights on structural properties of the Eu^3+ complexes, such as the high symmetry environment of the Eu^3+ ion in a single macrocyclic conformation and the presence of one water molecule in its inner coordination sphere. The overall quantum yield of luminescence of EuL1 is higher than for EuL2. However, their low values reflect the low overall sensitization efficiency of the energy transfer process, which is a consequence of the large distances between the metal center and the antenna, especially in the EuL2 complex. DFT calculations confirmed that the most stable conformation of the Eu^3+ complexes involves a combination of a square antiprismatic (SAP) geometry of the chelate and an extended conformation of the linker. The large calculated average distances between the metal center and the antenna point to the predominance of the Förster energy transfer mechanism, especially for EuL2. This study provides insights into the behavior of amyloid-targeted Ln^3+ complexes as optical probes, and contributes towards their rational design.

Pharmaceuticals and their metabolites are released into the environment by domestic, hospital, and pharmaceutical industry wastewaters. Conventional wastewater treatment technology does not guarantee effluents of high quality, and apparently clean water may be loaded with pollutants. In this study, we assess the performance and efficiency of free and immobilised cells of microalgae Nannochloropsis sp. in removing four pharmaceuticals, chosen for their occurrence or persistence in the environment. These are paracetamol, ibuprofen, olanzapine and simvastatin. The results showed that free microalgae cells remain alive for a longer time than the immobilised ones, suggesting the inhibition of cell proliferation by the polymeric matrix polyvinyl alcohol. Both cells, free and immobilised, respond differently to each pharmaceutical. The removal of paracetamol and ibuprofen by Nannochloropsis sp., after 24 h of culture, was significantly higher in immobilised cells. Free cells removed a significantly higher concentration of olanzapine than immobilised ones, suggesting a higher affinity to this molecule than to paracetamol and ibuprofen. The results demonstrate the effectiveness of Nannochloropsis sp. free cells for removing olanzapine and Nannochloropsis sp. immobilised cells for removing paracetamol and ibuprofen.

The development of single coulometric cells in combination with high performance liquid chromatography to dual cells and to the coulometric electrode array detector is described. An overview is given about the application of these methods in food chemistry. Easily oxidizable compounds, such as phenolic substances, pesticides, or vitamins, can be determined, as well as substances with high oxidation potentials or electroinactive compounds. Substances exhibiting poor electrochemical activity can be transformed to electroactive compounds by precolumn derivatization, postcolumn photochemical reactions, postcolumn enzyme reactors, or by using the oxidative/reductive mode for coulometric electrode array detection. Furthermore, it is shown that the interesting combination of high performance liquid chromatography with electrochemistry and mass spectrometry has opened further possibilities with respect to interpretation of redox reactions, drug metabolism studies, metabolomics, and electrochemical derivatization.

DL-2-Aminobutyric acid (alpha-aminobutyric acid or AABA) is a non-protein amino acid with important physiological properties, and with considerable relevance in different areas, such as fundamental research and pharmaceutical industry. In this paper, the binary mutual diffusion coefficients of AABA in non-buffered aqueous solutions (0.001-0.100) madm (3) at 298.15 K were measured. From these diffusion data, limiting values at infinitesimal concentration, D-0, as well as those of the thermodynamic factors, F-T, and activity coefficients, gamma, were estimated. These data for AABA were compared with the data previously obtained for ot-4-aminobutyric acid (GABA). The difference of the behaviour of these transport properties for both amino-acids was explained based on the structural differences for the monomeric zwitterionic species of AABA and GABA. Such structural differences are supported by both H-1 and C-13 NMR spectroscopy and theoretical calculations, which indicate that the predominant species of AABA in these solutions is the extended zwitterionic form in contrast with the curled one of GABA. (C) 2019 Elsevier Ltd.

ABSTRACT We report on solution aggregates and backbone conformation of poly(9‐undecyl‐9‐methyl‐fluorene) (PF1‐11) and poly(9‐pentadecyl‐9‐methyl‐fluorene) (PF1‐15), having two different side chains compared with poly(9,9‐dihexylfluorene) (PF6) and poly(9,9‐dioctylfluorene) (PF8) with two identical side chains. In the poor solvent methylcyclohexane (MCH), X‐ray scattering indicates that PF1‐11 and PF1‐15 appear as three‐dimensional aggregates (5–10 nm wide and thick), forming ribbon‐like agglomerates (correlation lengths of 100 nm). PF6 and PF8 appear as two‐dimensional aggregates (>10 nm wide and 2–3 nm thick) involving ribbon‐like agglomerates (correlation lengths much greater than 100 nm). Upon heating, all aggregates undergo a gel–sol transition which occurs at lower temperatures for PF1‐11 and PF1‐15 (<60°C) than for PF6 and PF8 (>80°C). In the good solvent toluene, PF1‐11 and PF1‐15 form networks of cylindrical particles. The mesh size and the cylinder radius are smaller in 24°C toluene (60 nm, 0.5 nm) than in 60°C MCH (300 nm, 1–2 nm). Nuclear magnetic resonance spectra in toluene‐ d 8 together with density functional theory calculations suggest higher torsion angles between polymer repeat units for PF6, PF8, and PF1‐11 (less planar conformation) and a gauche arrangement of the dihedral angles between the bridge carbon atom and the side chain methylene groups in PF1‐15. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57 , 826–837

Endocrine disrupting chemicals are a group of pollutants that can affect the endocrine system and lead to diseases and dysfunctions across the lifespan of organisms. They are omnipresent. They are in the air we breathe, in the food we eat and in the water we drink. They can be found in our everyday lives through personal care products, household cleaning products, furniture and in children’s toys. Every year, hundreds of new chemicals are produced and released onto the market without being tested, and they reach our bodies through everyday products. Permanent exposure to those chemicals may intensify or even become the main cause for the development of diseases such as type 2 diabetes, obesity, cardiovascular diseases and certain types of cancer. In recent years, legislation and regulations have been implemented, which aim to control the release of potentially adverse endocrine disrupting chemicals, often invoking the precautionary principle. The objective of this review is to provide an overview of research on environmental aspects of endocrine disrupting chemicals and their effects on human health, based on evidence from animal and human studies. Emphasis is given to three ubiquitous and persistent groups of chemicals, polychlorinated biphenyls, polybrominated diphenyl ethers and organochlorine pesticides, and on two non-persistent, but ubiquitous, bisphenol A and phthalates. Some selected historical cases are also presented and successful cases of regulation and legislation described. These led to a decrease in exposure and consequent minimization of the effects of these compounds. Recommendations from experts on this field, World Health Organization, scientific reports and from the Endocrine Society are included.