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101.
Dipl.‐Chem. Günther Thiele Thomas Krüger Prof. Dr. Stefanie Dehnen 《Angewandte Chemie (International ed. in English)》2014,53(18):4699-4703
The first inorganic lead(IV) compound without oxygen, nitrogen or halogen ligands attached to the lead atom was obtained as the potassium salt of the tetraselenidoplumbate(IV) anion [PbIVSe4]4?. It is stable under inert conditions which may enable the transfer of the chemistry of chalcogenidogermanate(IV) or chalcogenidostannate(IV) materials, to the lead homologues. 相似文献
102.
Insights into the AIEE of 1,8‐Naphthalimides (NPIs): Inverse Effects of Intermolecular Interactions in Solution and Aggregates 下载免费PDF全文
Sanjoy Mukherjee Prof. Dr. Pakkirisamy Thilagar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):8012-8023
Systematic structural perturbation has been used to fine‐tune and understand the luminescence properties of three new 1,8‐naphthalimides (NPIs) in solution and aggregates. The NPIs show blue emission in the solution state and their fluorescence quantum yields are dependent upon their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to quench the fluorescence due to the formation of excimers. In contrast, upon aggregation (in THF / H2O mixtures), the NPIs show aggregation‐induced emission enhancement (AIEE). The NPIs also show moderately high solid‐state emission quantum yields (ca. 10–12.7 %). The AIEE behaviour of the NPIs depends on their molecular rigidity and the nature of their intermolecular interactions. The NPIs 1 – 3 show different extents of intermolecular (π–π and C?H???O) interactions in their solid‐state crystal structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that an optimal balance of structural flexibility and intermolecular communication is necessary for achieving AIEE characteristics in these NPIs. 相似文献
103.
Hydroxymethylated Phyllobilins: A Puzzling New Feature of the Dioxobilin Branch of Chlorophyll Breakdown 下载免费PDF全文
Iris Süssenbacher Dr. Bastien Christ Prof. Dr. Stefan Hörtensteiner Prof. Dr. Bernhard Kräutler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):87-92
Colorless nonfluorescent chlorophyll (Chl) catabolites (NCCs) are formyloxobilin‐type phyllobilins, which are considered the typical products of Chl breakdown in senescent leaves. However, in degreened leaves of some plants, dioxobilin‐type Chl catabolites (DCCs) predominate, which lack the formyl group of the NCCs, and which arise from Chl catabolites by oxidative removal of the formyl group by a P450 enzyme. Here a structural investigation of the DCCs in the methylesterase16 mutant of Arabidopsis thaliana is reported. Eight new DCCs were identified and characterized structurally. Strikingly, three of these DCCs carry stereospecifically added hydroxymethyl groups, and represent bilin‐type linear tetrapyrroles with an unprecedented modification. Indeed, DCCs show a remarkable structural parallel, otherwise, to the bilins from heme breakdown. 相似文献
104.
Sanjoy Mukherjee Prof. Dr. Pakkirisamy Thilagar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):9052-9062
Three new NPI–BODIPY dyads 1 – 3 (NPI=1,8‐naphthalimide, BODIPY=boron‐dipyrromethene) were synthesized, characterized, and studied. The NPI and BODIPY moieties in these dyads are electronically separated by oxoaryl bridges, and the compounds only differ structurally with respect to methyl substituents on the BODIPY fluorophore. The NPI and BODIPY moieties retain their optical features in molecular dyads 1 – 3 . Dyads 1–3 show dual emission in solution originating from the two separate fluorescent units. The variations of the dual emission in these compounds are controlled by the structural flexibilities of the systems. Dyads 1 – 3 , depending on their molecular flexibilities, show considerably different spectral shapes and dissimilar intensity ratios of the two emission bands. The dyads also show significant aggregation‐induced emission switching (AIES) on formation of nano‐aggregates in THF/H2O with changes in emission color from green to red. Whereas the flexible and aggregation‐prone compound 1 shows AIES, rigid systems with less favorable intermolecular interactions (i.e., 2 and 3 ) show aggregation‐induced quenching of emission. Correlations of the emission intensity and structural flexibility were found to be reversed in solution and aggregated states. Photophysical and structural investigations suggested that intermolecular interactions (e.g., π–π stacking) play a major role in controlling the emission of these compounds in the aggregated state. 相似文献
105.
Polyurethane cationomer coats were synthesised on the basis of typical diisocyanates, properly selected polyether polyols, HO-tertiary amines and HCOOH as quaternisation reagents. The values of their surface free energy (SFE) parameters were obtained by the van Oss-Good method, with the use of the contact angle values which had been found by the goniometric method. Based on the obtained findings, empirical models were developed which made it possible to anticipate the effects of the raw material types on the SFE values of the produced coats. The possibility was noted to adjust the SFE values within 25–50 mJ/m2 by selecting carefully suitable parent substances. The principal consequences for the formation of improved hydrophobicity coats, applicable inter alia specialised protective coatings, were found to come not only from diisocyanate and polyol types but also from the alkylammonium cation structure which results from the use of different tertiary amines. The fundamental SFE lowering effect was noted when tertiary amines with 0–15 % of the 2,2,3,3-tetrafluoro-1,4-butanediol as a fluorinated chain extender was incorporated into polymer chains. 相似文献
106.
Katarína Kráľová František Šeršeň Matúš Peško Karel Waisser Lenka Kubicová 《Chemical Papers》2014,68(1):46-52
5-Bromo-(Br-PBA) and 3,5-dibromo-2-hydroxy-N-phenylbenzamides (Br2-PBA) inhibited photosynthetic electron transport (PET) and their inhibitory efficiency depended on the compound lipophilicity as well as on the electronic properties of the R substituent in the N-phenyl moiety. Br-PBA showed higher PET inhibiting activity than Br2-PBA with the same R substituent. The most effective inhibitors in the tested series were the derivatives with R = 3-F (Br-PBA; IC50 = 4.3 μmol dm?3) and R = 3-Cl (Br2-PBA; IC50 = 8.6 μmol dm?3). Bilinear dependence of the PET inhibiting activity on the lipophilicity of the compounds as well as on the Hammett constant, σ, of the R substituent was observed for both investigated series. Using EPR spectroscopy it was found that the site of action of the tested compounds in the photosynthetic apparatus is situated on the donor side of PS 2, in D· or in the Z·/D· intermediates. Interaction of the studied compounds with chlorophyll a and aromatic amino acids present in the pigment-protein complexes mainly in photosystem 2 was documented by fluorescence spectroscopy. 相似文献
107.
Dr. Christoph Kieninger Dr. Klaus Wurst Dr. Maren Podewitz Dr. Maria Stanley Dr. Evelyne Deery Dr. Andrew D. Lawrence Prof. Dr. Klaus R. Liedl Prof. Dr. Martin J. Warren Prof. Dr. Bernhard Kräutler 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20304-20311
The (formal) replacement of Co in cobalamin ( Cbl ) by NiII generates nibalamin ( Nibl ), a new transition-metal analogue of vitamin B12. Described here is Nibl , synthesized by incorporation of a NiII ion into the metal-free B12 ligand hydrogenobalamin ( Hbl ), itself prepared from hydrogenobyric acid ( Hby ). The related NiII corrin nibyric acid ( Niby ) was similarly synthesized from Hby , the metal-free cobyric acid ligand. The solution structures of Hbl , and Niby and Nibl , were characterized by spectroscopic studies. Hbl features two inner protons bound at N2 and N4 of the corrin ligand, as discovered in Hby . X-ray analysis of Niby shows the structural adaptation of the corrin ligand to NiII ions and the coordination behavior of NiII. The diamagnetic Niby and Nibl , and corresponding isoelectronic CoI corrins, were deduced to be isostructural. Nibl is a structural mimic of four-coordinate base-off Cbls , as verified by its ability to act as a strong inhibitor of bacterial adenosyltransferase. 相似文献
108.
Krüger A. L Nicolodelli G Villas-Boas P. R Watanabe A Milori D. M. B. P 《Plasma Chemistry and Plasma Processing》2020,40(6):1417-1427
Plasma Chemistry and Plasma Processing - Laser-induced breakdown spectroscopy (LIBS) has been considered a promising tool for agricultural analysis in the recent years due to its advantages over... 相似文献
109.
This paper reviews literature information on the behaviour of semivolatile organic compounds (SVOCs) in the indoor environment,
as well as the most likely emission sources. The consecutive stages of analytical procedures used for monitoring SVOCs in
indoor environments are described. The most common approaches used for collecting samples from the gas and particulate phases
are mentioned. The paper discusses and compares various types of sorbents and filters applied in dynamic, passive and denudational
techniques, as well as the techniques used to liberate the SVOCs, including Soxhlet, sonication and microwave extraction.
The main advantages and disadvantages of each technique are discussed, together with possible future trends. The approaches
commonly used during the final determination step, such as gas chromatography and liquid chromatography, are presented together
with their possible drawbacks, and ways of eliminating them are suggested. The review makes brief reference to the effects
of human exposure to SVOCs in house dust and discusses the main aspects of the analytical procedures used to monitor the presence
of SVOCs in this medium. 相似文献
110.
Hubert Hřebabecký Milan Dejmek Martin Dračínský Michal Šála Pieter Leyssen Johan Neyts Martina Kaniaková Jan Krůšek Radim Nencka 《Tetrahedron》2012,68(4):1286-1298
Azanorbornylpurine derivatives were prepared by Mitsunobu reaction of appropriate hydroxyazanorbornane derivative with 6-chloropurine or construction of purine base at azanorbornylamines. The prepared target compounds were evaluated for antiviral activity and effect on neuronal and muscle nicotinic acetylcholine receptors. 相似文献