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Wyświetlanie 1-4 z 4
Tytuł:
Związki alkoholanowe w syntezie nanomateriałów
The alkoxide compounds in the synthesis of nanomaterials
Autorzy:
John, Ł.
Sobota, P.
Powiązania:
https://bibliotekanauki.pl/articles/171978.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
alkoholany metali
związki molekularne
tlenkowe materiały ceramiczne
metal alkoxides
molecular compounds
oxide ceramic materials
Opis:
Polynuclear metal alkoxides are nearly as common in today’s chemistry as any other simple inorganic complexes and constitute an interesting family of species with a very broad structural diversity (Fig. 3 and Tab. 1) [14]. These compounds form structural motifs which range from simple bimetallic complexes to very specific aggregates that result from the versatile coordinating abilities of an alkoxo and aryloxo ligands (Fig. 1). For the last few decades, there has been a growing interest in the development of the chemistry of metal alkoxides. Such interest derives from their fascinating structural chemistry, interesting catalytic properties, and a high potential for industrial utilization. The fact that most of them can generate highly pure and well-defined metal oxides (Table 4) has resulted in high research activity in chemistry of materials. Alkoxides and their derivatives, e.g. organometallics, are easily accessible and consist inexpensive compounds. Moreover, alkoxide ligands are easily removable during thermal treatment in a relatively low temperatures compare to conventional methods involving inorganic salts. Such compounds already have metal-oxygen bonds established on molecular structure. Due to these, alkoxides can generate oxide ceramics in a single step – so-called single-source precursors (SSPs) [11]. SSPs deliver appropriate metal elements of a final oxide product(s) eliminating the need to match the reaction rates required from a multicomponent mixture. All of these features made the metal oxides derived from metal alkoxides highly pure products possessing specific properties, chemical and mechanical resistance, excellent functions and shapes. The aim of this article is to serve as a guide in understanding the principles in a one step strategy for oxide ceramics using metal alkoxide compounds. It includes synthesis of alkoxides and their derivatives, the concept of SSPs strategy and design of molecular precursors for oxide ceramic materials.
Źródło:
Wiadomości Chemiczne; 2011, 65, 9-10; 839-868
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of fRMSDchiral for mathematical description of mutual position between stereoisomers
Autorzy:
Urniaz, Rafal Damian
Powiązania:
https://bibliotekanauki.pl/articles/748148.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
fragment-level RMSD
chiral recognition
bioinformatics
molecular modeling
fragment-level RMSD, związki chiralne, stereoselektywność, bioinformatyka, modelowanie molekularne
Opis:
The ability of biological systems to recognize and distinguish between compounds is crucial for living systems. A detailed study of this mechanism seems to be an important supplement for analysis of possible contact interactions between compounds and environment. This process could be characterized by variety of descriptors respond to compounds’ structural and physicochemical properties. Usually, the measure of variation in molecule positions in the three dimensional space is realized by the Root Mean Square Deviation (RMSD) calculation. Here, the traditional concept of RMSD was readjusted as fragment-level RMSD (fRMSD) and applied for mathematical description of stereoisomers’ role in the chiral recognition process.
Źródło:
Mathematica Applicanda; 2015, 43, 1
1730-2668
2299-4009
Pojawia się w:
Mathematica Applicanda
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Materiały MOF, nowa rodzina sit molekularnych o niezwykłych właściwościach i możliwościach zastosowań
MOF materials, the new family of the molecular sieves with exceptional properties and possible applications
Autorzy:
Florczak, P.
Janiszewska, E.
Kędzierska, K.
Kowalak, S.
Powiązania:
https://bibliotekanauki.pl/articles/171820.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
organiczno-nieorganiczne sita molekularne
związki metaloorganiczne MOF
synteza
zastosowanie
właściwości
organic-inorganic molecular sieves
MOF
structure
synthesis
properties
applications
Opis:
The metal organic frameworks (MOFs) are a novel group of molecular sieves discovered in the last decade of the twentieth century. Most of conventional molecular sieves such as microporous zeolites and zeolite-like materials, ordered mesoporous materials (M41S) are typical inorganic compounds. Although their synthesis often involves an assistance of organic compounds acting as structure directing agents and organic solvents are sometimes applied during their crystallization, the organics are always removed from resulted products (mainly by calcinations). The MOFs are crystalline materials build of metal ions or ion clusters coordinatively bonded with organic segments (linkers) that form porous (one-, two-, or threedimensional) structures. The various coordination number of selected metal and the nature of organic linkers allow to prepare a great variety of structures with different properties. The inorganic components comprise a great variety of transition (e.g. Zn Cu, Fe, rare earths) and base metal (e.g. Al) cations of different valence. The organic linkers are functionalized compounds containing O, N, P, S atoms (i.e. carboxylates, phosphonates, sulfonates, cyanides, amines, imidazoles) enable to chelate the inorganic cations. The organic subunits can be additionally modified by substitution of other functional groups (halogens, hydroxyls, aminogroups). The MOF materials are mostly prepared similarly as zeolitic materials by crystallization in solvothermal conditions. The solvents (water or organic compounds) can play a role of templates, although sometimes additional structure directing agents are admitted into the initial mixtures. The crystallization is always conducted in moderate temperatures (20–200°C). After removal of solvents well ordered pore systems are available for selective adsorption and for other applications. The thermal stability of this family of molecular sieves is obviously lower than that of inorganic materials, but most of them can withstand heating at 350–400°C, which still makes them suitable for variety of potential applications. The adsorption properties of MOFs makes them very appealing for practical application. The recorded surface areas of some types are overwhelming and they surpass 5000 m2/g. The high adsorption capacity is very promising for storage of fuels (natural gas, hydrogen) or waste gases (CO2, SO2) as well as for their separation. The great and very fast growing variety of structures and chemical compositions brings also a hope to use them as efficient catalysts. The metal segments, functional groups in organic blocks as well as occluded or encapsulated species can play a role of catalytically active sites. The MOF materials can be also applied as matrices for sensors, pigments, and microelectronic or optical devices.
Źródło:
Wiadomości Chemiczne; 2011, 65, 5-6; 427-460
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of dibenzo[b,f]oxepine derivatives substituted in the aromatic ring
Synteza pochodnych dibenzo[b,f]f]oksepiny podstawionych w pierścieniu aromatycznym
Autorzy:
Tobiasz, Piotr
Krawczyk, Hanna
Powiązania:
https://bibliotekanauki.pl/articles/2057911.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
stylben
dibenzo[b,f]oksepiny
fotofarmakologia
fotochromowe przełączniki molekularne
związki azowe
stilbenes
dibenzo[b,f]oxepines
photopharmacology
molecular photoswitches
azo compounds
Opis:
Stilbene derivatives are characterized by many beneficial biomedical properties. They show, inter alia, chemopreventive [28], anti-inflammatory and antioxidant properties [29]. One of the most popular stilbene derivatives are combretastatins, which can inhibit the polymerization process of microtubules [30]. Another stilbene derivative is, for instance, resveratrol, which is characterized by wide anti-cancer properties [31]. Dibenzo[b,f]oxepines also show advantageous and interesting biomedical properties. These compounds are stilbene analogs in which the two aromatic rings bond with each other with a vinyl bridge and an oxygen atom. Many dibenzo[b,f]oxepines have strong antipsychotic, anti-inflammatory, anti-depressant, insecticidal, anti-epileptic and anticancer properties [5]. Stilbenes and their precursors – oxepines, can be derived from azo compounds that are potential molecular photoswitches. These photoswitches are used in the socalled photopharmacology. The scope of photopharmacology is designing, synthesis, studying and using drugs, which activity can be controlled by light. The purpose of photopharmacology is also to solve the problem of off-target activity and severe side effects by establishing an external modality for controlling the action of the drug. The use of such drugs in treatment could prevent systemic and environmental side effects through the selective activation of them at the molecular target [1]. These molecular photoswitches based on oxepine ring could be extremely useful in photopharmacological therapy. The combination of azo group changing its configuration with the dibenzo[b,f]oxepine group should lead to the creation of interesting compounds. This is a promising combination of the medical properties of this bioactive compound with the function of the molecular photoswitch. A method of the synthesis of a series of azo dibenzo[b,f]oxepine derivatives was developed and implemented. Synthesized compounds can be used in the future as potential molecular photoswitches. For this purpose, a 4-step synthesis was conducted, starting from the simplest substrates – a benzaldehyde derivative and 2,4-dinitrotoluene (schem. 1).
Źródło:
Wiadomości Chemiczne; 2021, 75, 11-12; 1238--1257
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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