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New 2‐(di)methoxythienyl substituted ligands of the 2,2′‐bipyridine series containing various aromatic substituents at the C3 position were obtained in yields of up to 90 %. A "1,2,4‐triazine" methodology involving an SNH reaction in 1,2,4‐triazine followed by an aza‐Diels‐Alder reaction with 2,5‐norbornadiene was used to synthesize the target compounds. When the Diels‐Alder reaction was carried out in an autoclave, an unexpected demethylation reaction was observed, leading to the formation of oxo‐thienyl substituted products. A mechanism for the reaction that occurred has been proposed on the basis of identified byproducts. Preliminary studies on the photophysical and coordination properties of the obtained compounds were also carried out. In particular, the possibility of obtaining a platinum(II) complex with the demethylation product was demonstrated. [ABSTRACT FROM AUTHOR]

A series of novel 2‐(2‐pyridyl)quinazoline luminophores containing a donor aryl fragment at position 4 and methyl or methoxy groups at benzene ring has been synthesized by efficient three‐step route. The linear optical properties have been studied by UV/Vis absorption and photoluminescence spectra in two solvents. We revealed that introduction of additional methyl group or the replacement of methyl substituents with methoxy ones lead to sequentially shift of absorption and emission maximum to blue region. 9H‐Carbazol‐9‐yl‐containing derivative is characterized by hypsochromically shifted absorption band compared to its NEt2 and NPh2 counterparts. Unlike 9H‐carbazol‐9‐yl‐derivative, Et2N‐ and Ph2N‐bearing quinazolines demonstrate considerable decrease in quantum yield values when going from toluene to MeCN. Solvatochromic properties have been explored, the pronounced bathochromic shift was observed in fluorescence spectra with the increase of solvents polarity. Moreover, the compounds show significant shift of emission band with the increase of water fraction in DMSO/H2O mixture. Two‐photon optical properties have been also studied, the two‐photon absorption cross‐sections in MeCN and toluene reached 120 GM and 210 GM, respectively. The presence of additional methyl group has little impact on δTPA value, while introduction of methoxy substituents dramatically decreases TPA cross sections. Additionally, a quantum‐chemical calculations of synthesized compounds were performed to support the experimental data. [ABSTRACT FROM AUTHOR]

The increasing discharge of antibiotic wastewater leads to increasing water pollution. Most of these antibiotic wastewaters are persistent, strongly carcinogenic, easy to bioaccumulate, and have other similar characteristics, seriously jeopardizing human health and the ecological environment. As a commonly used wastewater treatment technology, non-homogeneous electro-Fenton technology avoids the hazards of H2O2 storage and transportation as well as the loss of desorption and reabsorption. It also facilitates electron transfer on the electrodes and the reduction of Fe3+ on the catalysts, thereby reducing sludge production. However, the low selectivity and poor activity of electro-synthesized H2O2, along with the low concentration of its products, combined with the insufficient activity of electrically activated H2O2, results in a low ∙OH yield. To address the above problems, composites of layered bimetallic hydroxides and carbon materials were designed and prepared in this paper to enhance the performance of electro-synthesized H2O2 and non-homogeneous electro-Fenton by changing the composite mode of the materials. Three composites, NiFe layered double hydroxides (LDHs)/reduced graphene oxide (rGO), NiMn LDHs/rGO, and NiMnFe LDHs/rGO, were constructed by the electrostatic self-assembly of exfoliated LDHs with few-layer graphene. The LDHs/rGO was loaded on carbon mats to construct the electro-Fenton cathode materials, and the non-homogeneous electro-Fenton oxidative degradation of organic pollutants was realized by the in situ electrocatalytic reduction of O2 to ∙OH. Meanwhile, the effects of solution pH, applied voltage, and initial concentration on the performance of non-homogeneous electro-Fenton were investigated with ceftazidime as the target pollutant, which proved that the cathode materials have an excellent electro-Fenton degradation effect. [ABSTRACT FROM AUTHOR]

Several new derivatives of 2,2′‐bipyridines with a spacer group separated from the 2,2‐bipyridine fragment, namely, an ethynyl fragment, were obtained using the Sonagashira cross‐coupling reaction. The resulting derivatives were physically adsorbed on platinum electrode and were then used as activators of the catalytic activity of a platinum electrode in the reaction of cholesterol electrooxidation in an acetonitrile medium. Sensitivity, limit of detection and detectable concentration range were calculated, and the best results was established as 6.2±0.6 μA/mM, 0.08 mM and 0–0.3 mM, respectively. These results show that the prepared compounds adsorbed on platinum electrode are perspective systems for developing of new enzymeless cholesterol sensor based on them. [ABSTRACT FROM AUTHOR]

A series of new 2-(indol-3-yl)-6-(hetero)aryl substituted pyridines, 2-(indol-3-yl)-5-phenyl-substituted 2,2′-bipyridine and 5-aryl-6-(pyrrol-2-yl) substituted 2,2′-bipyridines were synthesized as push–pull fluorophores/probes by using a sequence of nucleophilic substitution reaction of hydrogen (SNH) and inverse-demand Diels–Alder reaction. For the obtained compounds, photophysical properties were studied. All the compounds displayed ICT-activity with a large Stokes shift (up to 197 nm) and PLQY up to 0.28. Due to dual emission in polar solvents, one specific probe was able to respond to the action of the local pH changes in the microenvironment and exhibit AIE-activity. The fluorescence titration data at different pH were analyzed to estimate a pKa value of 4.50 for that specific probe. The AIE behavior was further confirmed by means of time-resolved fluorescence lifetime measurements as well as UV-vis spectroscopic studies. The correlation of the influence of the nature of substituents on the degree of ICT state was established based on the analysis of charge transfer (CT) indices and the calculated interfragment charge transfer (IFCT) values. Finally, the fluorophores reported in this study were successfully applied for cellular imaging. [ABSTRACT FROM AUTHOR]

New tripod-type 2,2'-bipyridine ligand consisting of a central polyaminocarboxylic moiety for the coordination to lanthanide cations and three appended 5-phenyl-2,2'-bipyridine fragments for the coordination to various transition metal cations have been prepared. A europium complex ofthis ligand was prepared, and its photophysical properties and a luminescent response towards transition metal salts (particularly, [CdI.sub.2], Cd[(OAc).sub.2], Zn[([ClO.sub.4]).sub.2], [Cu(OAc).sub.2], and HgC[l.sub.2]) have been studied. Europium cation luminescence quenching in the presence of transition metal salts in solution was observed in all cases. In addition, it was observed that the fluorescent response of the europium complex was quite individual depending on the type of the metal salt. The obtained data were compared with the earlier published data for some lanthanide complexes bearing additional sites for the chelation of transition metal cations. europium complex, luminescence, 2,2'-bipyridine, polyaminocarboxylic acid, ditopic ligand. Resume : Nous avons synthetise un nouveau ligand de type tripode a base de 2,2= bipyridine qui consiste en une unite polyaminocarboxylique centrale se coordonnant a des cations de lanthanides et a laquelle sont attaches trois fragments 5 phenyl-2,2' bipyridine se coordonnant a divers cations de metaux de transition. Nous avons prepare un complexe d'europium avec ce ligand et en avons etudie les proprietes photophysiques et la reponse luminescente a l'egard de sels de metaux de transition (en particulier le [CdI.sub.2], le Cd[(OAc).sub.2], le Zn([ClO.sub.4]).sub.2], le Cu[(OAc).sub.2] et le HgC[l.sub.2]). Nous avons observe en solution une extinction de luminescence du cation d'europium en presence de tous les sels de metaux de transition etudies. En outre, nous avons constate que la reponse fluorescente du complexe d'europium etait essentiellement propre au type de sel metallique. Nous avons compare les donnees obtenues avec celles de publications anterieures qui portaient sur certains complexes de lanthanides dotes d'autres sites de coordination chelatant des cations de metaux de transition. [Traduit par la Redaction] Mots-cles: complexe d'europium, luminescence, 2;2'-bipyridine, acide polyaminocarboxylique, ligand ditopique., Introduction Today, lanthanide (III) cation complexes are of great interest due to their wide applications. (1) In particular, lanthanide complexes that are luminescent in the visible spectrum are commonly used [...]