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Wyświetlanie 1-2 z 2
Tytuł:
Karbeny N-heterocykliczne : synteza i zastosowanie
N-heterocyclic carbenes : synthesis and applications
Autorzy:
Malinowska, M.
Hryniewicka, A.
Powiązania:
https://bibliotekanauki.pl/articles/171528.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
karbeny N-heterocykliczne
sole imidazolidyniowe
katalizator metatezy
organokataliza
reakcja sprzęgania
N-heterocyclic carbenes
imidazolinium salts
methatesis catalysts
organocatalysis
coupling reactions
Opis:
N-Heterocyclic carbenes (NHCs) are powerful tools in organic chemistry, with numerous applications in academic and industrial laboratories. They are usually defined as singlet carbenes, in which the divalent carbonic centre is connected directly to at least one nitrogen atom in the heterocycle [1]. They have played an important role in organic chemistry ever since the first evidence of their existence. The isolation of stable, free 1,3‑diadamantylimidazol-2-ylidene (IAd, Fig. 1) by Arduengo et al. in 1991 was a milestone in the chemistry of carbenes [2]. From the beginnings as academic curiosities, N‑heterocyclic carbenes today are very useful compounds in a variety of organic transformations (Fig. 13). NHCs are neutral σ-donors, which form very strong bonds with the majority of transition metals (stronger than phosphines). These compounds are easy-to-make ligands with great potential in homogeneous catalysis (mainly ruthenium and palladium complexes) for large number of reactions, including the coupling reactions (Heck, Negishi, Stille, Suzuki or Sonogashira reactions) and olefin metathesis [3]. Moreover, they are very useful as organocatalysts used in the benzoin condensation, the Stetter reaction and ring-opening polymerization (ROP) or transesterification [4]. In this review, we aim to give an overview of the properties and applications of NHCs, which we expect will be a useful introduction for chemists interested in studying and applying these important compounds. The first part of this review is devoted to the main synthetic routes to NHCs, their properties and reactivity. In the second part we describe the metal complexes with NHCs as homogeneous catalysts and their applications in various types of reactions. At the end of this part of the paper the use of NHCs as organocatalysts is presented.
Źródło:
Wiadomości Chemiczne; 2015, 69, 3-4; 227-253
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oligonukleotydy DNA jako warstwy receptorowe sensorów elektrochemicznych
DNA oligonucleotides as receptor layers of electrochemical sensors
Autorzy:
Górski, Ł.
Ziółkowski, R.
Bala, A.
Jarczewska, M.
Malinowska, E.
Powiązania:
https://bibliotekanauki.pl/articles/171556.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
biosensor
metale ciężkie
kwasy nukleinowe
samoorganizujące się monowarstwy
woltamperometria
znaczniki redoks
biosensors
heavy metals
nucleic acids
self-assembled monolayers
voltammetry
redox indicators
Opis:
The need for elaboration of analytical devices of small dimensions and the accessibility of novel nanomaterials caused the increase in the number of publications referring to the development of biosensors. DNA-based biosensors are of special interest and they were primarily used for the determination of a specific sequence which is crucial in the detection of cancer, genetic mutations, pathogens, as well as analysis of modified food. Interestingly, they could be also applied for the detection of other analytes including heavy metal ions, especially in connection with electrochemical techniques. It should be noted that the design of DNA biosensor concerns not only the development of transducer, but also careful preparation of sensing layer and the choice of the method of analytical signal generation. Selectivity is one of the essential parameter of the biosensor that determines its utility, particularly in real samples of complex matrices. In case of DNA sensors dedicated for the detection of complementary sequence, high selectivity is provided by the hybridization process. A pronounced specificity of sensing layer-analyte interaction can be also achieved with the use of functional nucleic acids - aptamers, which change their conformation upon binding an analyte. Herein, DNA-modified electrodes were firstly used for the detection of uranyl ions, as they exhibit high affinity towards phosphate moieties of nuclec acids. It was shown that UO2 2+ interacts with sensing layer independently from the chosen oligonucleotide sequence. Moreover, the influence of Pb2+ was reduced by elimination of adenine, which strongly interacts with lead ions. Another oligonucleotide-based sensor was developed for detection of mercury ions. The results indicate that Hg2+ concentration can be determined only with the use of sequence containing 100% thymine residues. Oligonucleotide-based sensor with receptor layer containing aptamers was elaborated for the detection of Pb2+ ions. In the presence of lead cations, an aptamer probe forms a G-quadruplex structure, a proposed biosensor could be characterized with selectivity towards Pb2+ The performance of DNA-based sensors for UO2 2+, Hg2+ and Pb2+ ions was optimized and addressed the choice of the manner of analytical signal generation, the influence of electrode modification with blocking agent, sensitivity dependence on the oligonucleotide sequence and the possibility of regeneration of sensing layer. Finally, the utility of proposed DNA sensors was tested by analysis in real samples.
Źródło:
Wiadomości Chemiczne; 2015, 69, 5-6; 325-336
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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