Влияние фосфатных связующих на физико-механические свойства периклазохромитовых огнеупоров

У данній статті наведено та порівняно фізико-механічні властивості периклазо-хромітових матеріалів в залежності від різних типів фосфатних зв’язуючих та введення різних домішок. Визначено, що найбільш раціональним є введення триполіфосфату натрію.In given clause are resulted and the physycal-mechanical properties periclase-cgromite of materials are compared depending on different of types phosphate binding and introduction of the various additives. Is determined, that most rational is the introduction treepolyphosphate sodume

Aza-macrocyclic triphenylamine ligands for G-quadruplex recognition

A new series of triphenylamine-based ligands with one (TPA1PY), two (TPA2PY) or three pending aza-macrocycle(s) (TPA3PY) have been synthesised and studied by means of pH-metric titrations, UV/Vis spectroscopy and fluorescence experiments. The affinity of these ligands for G-quadruplex (G4) DNA and its selectivity over duplex DNA were investigated by FRET melting assays, fluorimetric titrations and circular dichroism (CD) spectroscopy. Interestingly, the interaction of the bi- and specially the tri-branched ligand with G4 leads to a very intense red-shifted fluorescence emission band which may be associated with intermolecular aggregation between the molecule and the DNA. This light-up effect allows the application of the ligands as fluorescence probes to selectivity detect G4

Development of polyamine substituted triphenylamine ligands with high affinity and selectivity for G-quadruplex DNA

Currently significant efforts are devoted to designing small molecules able to bind selectively to guanine-quadruplexes (G4s). These non-canonical DNA structures are implicated in various important biological processes and have been identified as potential targets for drug development. Previously, we reported a series of triphenylamine(TPA)-based compounds including macrocyclic polyamines, which display high affinity towards G4 DNA. Following from this initial work, herein we present a series of second-generation compounds, in which the central TPA has been functionalised with flexible and adaptive linear polyamines, aiming to maximise the selectivity towards G4 DNA. The acid-base properties of the new derivatives have been studied by means of potentiometric titrations, UV-Vis and fluorescence emission spectroscopies. The interaction with G4s and duplex DNA has been explored using FRET melting assays, fluorescence spectroscopy and circular dichroism. Compared to our previously TPA derivatives with macrocyclic substituents, the new ligands reported herein retain the G4 affinity, but display two orders of magnitude higher selectivity for G4 vs. duplex DNA, most likely due to the ability of the linear substituents to embrace the G4 structure

Structural-topological preferences and protonation sequence of aliphatic polyamines: a theoretical case study of tetramine trien

A large set of lowest and medium energy conformers of aliphatic tetramine trien was used to uncover structural-topological preferences of poliamines. Numerous common structural features among HL and H2L tautomers were identified, e.g., H-atoms of protonated functional groups are always involved in intramolecular NH•••N interactions and they result in as large and as many as possible rings in lowest energy conformers. Largest, 11-membered, molecular rings stabilize a molecule most and they appeared to be strain free whereas 5-memebred intramolecular rings were most strained (all formed due to NH•••N interactions). The CH•••HC interactions with QTAIM-defined atomic interaction lines were also found but, surprisingly, mainly in the lowest energy conformers of HL tautomers. According to the non-covalent interaction-based (NCI) analysis, 5- memebered rings formed by CH•••HC interactions are not strained and, in general, 3D NCI isosurfaces mimic those obtained for weaker NH•••N interactions. Also, 3D NCI isosurfaces found for NH•••N and CH•••HC interactions, regardless whether linked or not by an atomic interaction line, appeared to be indistinguishable. Using lowest energy conformers, theoretically predicted mixture of primary (HLp) and secondary (HLs) forms of trien was found to be in accord with the literature reports; using linear conformers resulted in predicting HLs as the only tautomer formed. In contrast to HF, the overall performance of B3LYP was found satisfactory for the purpose of the study.National Research Foundation of South Africa (Grant Numbers 87777) and the University of Pretoria.http://link.springer.com/journal/8942016-06-30hb201