Wyniki wyszukiwania - BazTech

1

Synergizm kompleksów metaloorganicznych z półprzewodnikami do fotokatalitycznego generowania wodoru

Grabowska-Musiał Ewelina

Wiadomości Chemiczne

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2024

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[Z] 78, 3-4

263--278

EN

Currently, considerable attention is paid to durable, stable and energy-saving systems for photocatalytic water decomposition. Traditional photocatalytic systems are mainly based on semiconductor materials surface-modified with noble metals or inorganic cocatalysts. Recently, significant attention has been paid to hybrid systems in which semiconductor materials are integrated with metal complexes, which seem to be an effective strategy for constructing efficient photocatalytic systems for water decomposition. This review focuses on examining the possibility of obtaining photoactive materials by integrating semiconductors with compounds of various metal ions: platinum, nickel and cobalt. The aim of such integration is to increase the efficiency of hydrogen production from water and obtain the so-called "green energy".

2

Ignition compositions for use in ramjet engines

Szemlińska Natalia, Nita Marcin, Bilar Adam, Perkowski Witold

Materiały Wysokoenergetyczne

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2023

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T. 15

113--130

EN

The results of testing pyrotechnic compositions used in the ignition systems of a laboratory ramjet engine, are presented. Black powder (BP) and its formulations with a mixture of boron, potassium nitrate(V) (KNO3) and polymer binder were used as reference compositions. To modify the combustion characteristics of these formulations, additives in the form of energetic coordination complexes were utilized. The method of synthesis and results of tests carried out on the selected compounds (including sensitivity to friction and impact) is presented. The prepared pyrotechnic compositions were tested in a targeted ignition system to examine the effect of the addition of the coordination complexes on the burning speed of the mixture. The results obtained indicate that the addition of selected complex compounds increases the pressures generated by mixtures containing KNO3 and boron. This effect was not observed in the case of compositions based on BP.

PL

W pracy przedstawiono wyniki badań mieszanin pirotechnicznych wykorzystywanych w układach zapłonowych laboratoryjnego silnika strumieniowego. Jako kompozycje bazowe zastosowano proch czarny oraz jego mieszaniny z układem zawierającym bor, azotanu(V) potasu (KNO3) i lepiszcze polimerowe. W celu modyfikacji charakterystyk spalania sporządzonych kompozycji, wprowadzono dodatki w postaci energetycznych związków kompleksowych. Zaprezentowano metodę otrzymywania zastosowanych modyfikatorów oraz wybrane wyniki badań tych związków (m.in. wrażliwość na tarcie i uderzenie). Sporządzone mieszaniny pirotechniczne badano w docelowym układzie zapłonowym w celu sprawdzenia wpływu obecności modyfikatora na prędkość spalania kompozycji. Uzyskane wyniki badań wskazują, że dodatek wybranych związków kompleksowych wpływa na zwiększenie wartości ciśnień generowanych przez mieszaniny zawierające KNO3 i bor. Wpływu tego nie zauważono w przypadku kompozycji bazujących na prochu czarnym.

3

Explosive Coordination Materials : Acyclic Ligands - Review

Rećko Judyta

Central European Journal of Energetic Materials

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2022

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Vol. 19, no. 4

365--378

EN

Coordination explosives form a significant group of energetic materials, which are mainly considered as novel primary explosives. Due to their modular structure, these compounds offer many possibilities for modifying their physicochemical and energetic properties. In this review the properties of complexes containing molecules such as ammonia, hydrazine, ethylenediamine, carbohydrazide, and guanidine derivatives are presented. The types of ligands and their influence on the physicochemical properties and detonation parameters are discussed.

4

Funkcjonalizowane klatkowe silseskwioksany : wybrane strategie syntezy i właściwości koordynacyjne na przykładzie metali 13 grupy

Szybisty Aleksandra, Wytrych Patrycja, Ejfler Jolanta, John Łukasz

Wiadomości Chemiczne

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2021

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[Z] 75, 3-4

293--318

EN

Completely condensed POSS compounds have a cage structure built of Si-O bonds, which makes their electronic properties similar to those of silica and silicates. Moreover, due to their relatively inelastic structure, they impose a coordination geometry on the metal atom, imitating the geometry imposed by silica. Due to the above-mentioned properties, homogeneous models based on silsesquioxanes may not only allow for a better understanding of the nature of heterogeneous catalysts at the molecular level, but also may act as valuable catalysts themselves. Many coordination compounds of main group metals, transition metals and lanthanides have already been obtained. From among the group 13 metals of which this work is concerned, coordination entities of boron, aluminum, gallium, thallium, and indium have been prepared and analyzed so far. They turned out to be suitable models for heterogeneous catalysts, in some cases showing catalytic properties themselves.

5

Aminy biogenne w aspekcie ich roli w organizmach żywych

Jastrząb R., Tylkowski B.

Wiadomości Chemiczne

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2016

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[Z] 70, 1-2

57--79

EN

Although polyamines (PA) belong to relatively simple aliphatic substances, their role in life processes of animals and plants is of key importance [1–5]. The group of the most important amines, called biogenic ones includes: Spermine (Spm): H2N(CH2)3NH(CH2)4NH(CH2)3NH2 Spermidine (Spd): H2N(CH2)3NH(CH2)4NH2 Putrescine (Put): H2N(CH2)4NH2. Of secondary importance are homologues of biogenic amines, occurring in lower contents in living organisms [2, 6–8]: 1,3-diaminopropan: H2N(CH2)3NH2 Cadaverine: H2N(CH2)5NH2 Homospermidine: H2N(CH2)4NH(CH2)4NH2 Norspermine (3,3,3-tet): H2N(CH2)3NH(CH2)3NH(CH2)3NH2 Thermospermine: H2N(CH2)3NH(CH2)4NH(CH2)4NH2 Caldopentamine: H2N(CH2)3NH(CH2)3NH(CH2)3NH(CH2)3NH2. The first polyamine discovered in a living organism was tetramine, a spermine crystallised out of sperm in 1678 by Van Leewenkeuk [9]. Putrescine was discovered in the end of the 19th century in microbes and then triamine: spermidine was discovered in the beginning of the 20th century [2]. Later studies have shown that in animal cells spermidine and spermine occur at elevated levels, while in prokaryotes spermidine and putrescine contents are dominant. Putrescine, spermidine, 1,3-diaminopropan, homospermidine, norspermidine, and norspermine have been found in many gramnegative bacteria and algae [7, 10, 11]. Total concentration of PA in living organisms is on the order of millimols, however, the concentration of free polyamines is much lower. A low level of free amines follows from the fact that they are involved in noncovalent interactions with biomolecules occurring in living organisms such as nucleic acids, proteins, or phospholipids. High concentrations of non-bonded polyamines have been detected first of all in young molecules in the process of growth, in particular in rapidly proliferating cancer cells [6, 12]. Elevated levels of free polyamines have been observed, e.g. in breast, colon, lung, prostate, and skin tumours, accompanied by changed levels of enzymes responsible for biosynthesis and catabolism of polyamines. Because of the increased level of free polyamines and a tendency of their interaction with nucleic acids and other bioligands, these compounds have become objects of intense study [1, 13–19]. There is no doubt that the regulation of biosynthesis of polyamines and catabolism is one of the most important pathways in the search strategy for chemoprevention and chemotherapeutic drugs [14, 15, 20–36]. The present state of knowledge of these processes, their significance in biological systems, and their application in medicine are presented in subsequent sections of this chapter.

6

Dichloran(VII) akwatri(4-amino-1,2,4 triazol)disrebranowy inicjujący materiał wybuchowy

Borkowski J., Nita M., Warchoł R.

Problemy Techniki Uzbrojenia

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2013

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R. 42, z. 126

71--77

PL

Otrzymano i wstępnie scharakteryzowano nowy inicjujący materiał wybuchowy z grupy związków koordynacyjnych. Związek ten składa się z kationów srebra, które pełnią funkcje jonów centralnych, ligandów w postaci cząsteczek 4-amino-1,2,4-triazolu oraz anionów bogatych w aktywny tlen - reszt kwasu chlorowego(VII). Potwierdzeniem proponowanej struktury związku są uzyskane wyniki analizy elementarnej. Nowo otrzymany kompleks scharakteryzowano pod kątem wrażliwości na tarcie, uderzenie i promieniowanie laserowe, jak również zdolności pobudzania detonacji w kruszącym materiale wybuchowym. Za pomocą metody termograwimetrycznej wyznaczono jego odporność termiczną. Ostatecznie na bazie otrzymanego związku opracowano i zbudowano laboratoryjną elektryczną spłonkę pobudzającą.

EN

As a result of the research, a new primary explosive from a group of coordination compounds was prepared and preliminarily characterized. The obtained compound was analyzed in order to confirm its chemical composition and structure. These analyzes included the determination of C, H, N contents and TG thermogram. Density, sensitivity to friction, impact, laser radiation and detonator tests were also preformed. It is a detonat with moderate sensitivity to thermal (decomposition above 200 °C) and mechanical stimuli (sensitivity to friction 30 N, sensitivity to impact 2 J).

7

Inicjujące materiały wybuchowe z grupy związków kompleksowych

Cudziło S., Nita M.

Wiadomości Chemiczne

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2010

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[Z] 64, 3-4

195-223

EN

For more than one hundred years, mercury fulminate (MF), lead azide (LA) and lead styphnate (LS) have been used as primary explosives (Fig. 1). They are very good initiatory explosives but they also suffer from serious drawbacks, such as: (a) extremely high sensitivity to mechanical stimuli, (b) thermal, hydrolytic, and chemical instability or lack of resistance to light, (c) incompatibility with metals commonly used in initiating devices, (d) high toxicity of the compounds themselves and their decomposition products [1, 2]. The ongoing search for new primary explosives is aimed at finding materials safer in production and use which do not contain heavy metals and exhibit better initiating performance than the multicomponent compositions being used now. The replacements of the present primaries should be more resistant to accidental stimuli (electrostatic discharge, impact, friction), but they must reliably inflame or detonate, e.g. upon exposure to flame, electrically heated wire or strike with a firing pin in stab and percussion initiators. However their thermal stability should not be too low in order to avoid unexpected explosions of ammunition exposed to heat flow from a fire. On the other hand some of the materials (detonants) must be capable of fast transition from deflagration to detonation. It is not easy to reconcile so many contradictory demands, but from the recently published papers, it appears that it may be possible [3–5]. It has been confirmed many times that some complex compounds with a general formula Mx(L)y(XO)z where M denotes a transition metal cation, L is a nitrogen rich ligand, and XO is an oxygen containing anion are effective primary explosives [3]. The cation plays structure-creating role (i.e. coordinates other molecules) providing stability of the compound and required level of safety. Usually it is also a catalyst of the first stage of decomposition which assures a rapid deflagration to detonation transition – inherent feature of primary explosives. In order to maximize the heat effect of decomposition, the oxygen balance of the compounds ought to be close to zero. Thanks to this the initiating performance of the new primaries may be higher than that of azides and flumintaes. In this work we present a review of papers devoted to synthesis, chemical composition, molecular structure and explosive properties of primary explosives from the group of coordination compounds. A lot of attention was paid especially to the explosives that have already been used in initiating devices and those with unique properties, e.g. highly sensitive to laser radiation. To systematize the review, the title compounds were divided into groups which distinguishing feature was the kind of ligand.

8

Efektywność grup donorowych nukleotydów w reakcjach z jonami metali w układach podwójnych i potrójnych z udziałem tetramin

Gąsowska A.

Wiadomości Chemiczne

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2007

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[Z] 61, 5-6

339-359

EN

Nucleotides, being multifunctional ligands with donor nitrogen and oxygen atoms, take part in the majority of selective and specific processes occurring in nature [1-15]. It has been established that nucleotides react with the polyamines (biogenic amines) present in the living organisms and take part in genetic information transfer [16-24]. Nucleotides are composed of a purine or pyrimidine base, sugar residua and phosphate groups (Fig. 1) [25-27]. Each of the three components have potential centres of interaction with metal ions [28-29]. Because of the wide diversity of coordination possibilities there are often controversies as to the mode of coordination even in simple complexes with metal ions. Some authors claim that only nitrogen atoms of the nucleotide are effectively engaged in the metallation [30-43], while others maintain that it requires a combined engagement of nitrogen atoms and phosphate group [44-71]. There are also researchers who point to the involvement of only phosphate group of the nucleotide in the metallation [72-77]. The reaction of nucleotides with tetramines results in the formation of molecular complexes (Fig. 3) [78-88]. In the literature to date, there is no agreement as to the character of interactions and effectiveness of nucleotide donor groups in the formation of adducts with polyamines [80-82, 85-87, 89, 90]. According to some authors, the interaction between a nucleotide and polyamines in the metal-free systems has a noncovalent ion-ion or ion-dipole nature and the stability of molecular complexes is determined by the number of active centres in the reagents and the structural factor [80-84, 87]. According to other authors, it is a typical electrostatic interaction and the adduct stability is determined by the charge of the reagents [85, 89]. In the adducts formed by nucleotides with polyamines, the main interaction centres of a nucleotide are endocyclic nitrogen atoms and a phosphate group (the latter undergoes deprotonation already at a low pH), while in the case of tetramine the interaction centres are the NHx+ groups [77, 80-87, 89-91]. In the ternary systems of metal/nucleotide/tetramine, the following heteroligand molecular complexes are formed: MLźźźźźźHxL' (x = 4, HxL'-fully protonated polyamine) (Fig. 4) [80-82, 91, 94, 96], mixed protonated complexes MLHxL' (x = 1, 2, 3) (Fig. 5) [81, 82, 92, 96] and MLL' type complexes (Fig. 6) [81, 82, 91]. A significant influence of polyamines on the character of interactions of nucleotides with metal ions has been noted [80-82, 90-96]. In molecular complexes, the fully protonated polyamine is located in the outer coordination sphere. In the MLHxL' type complexes, the deprotonated nitrogen atoms of tetramine are involved in the coordination, while its protonated centres -NHx+ take part in noncovalent interactions that additionally stabilise the complex [81, 82, 92, 96, 97]. In the MLL' type complexes, oxygen atoms of nucleotide phosphate group and deprotonated nitrogen atoms of tetramine are in the inner coordination sphere, while nucleotide donor nitrogen atoms do not take part in the metallation [81, 82, 91].