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Wyświetlanie 1-9 z 9
Tytuł:
2,2'- Dihydroksy-1,1'-binaftyl (BINOL ) i jego pochodne. Wybrane syntezy i zastosowanie. Część I
2,2'-Dihydroxy -1,1'-binaphthyl (BINOL ) and its derivatives: Selected synthesis methods and applications. Part I
Autorzy:
Krasowska, D.
Powiązania:
https://bibliotekanauki.pl/articles/172527.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
BINOL
atropoizomery
utleniające sprzęganie
enancjoselektywna synteza
chiralne ligandy
atropoisomers
oxidative coupling
optical resolution
enantioselective synthesis
chiral ligands
Opis:
1,1’-Binaphthyl and its derivatives represent a particular class of chemical molecules which chirality results from the restricted rotation about single bond of the two naphthalene rings. This generates the chirality axis. Therefore 1,1’-binaphthyl derivatives exist as two enantiomeric forms called atropoisomers. Moreover, 1,1’- binaphthyls with substituents at 2,2’ position exhibit higher rotational barriers around the 1,1’-axis, which affect a very stable chiral configuration. The classical examples of such molecules is 2,2-dihydroxy-1,1’-binaphthyl (BINOL ), which has become one of the most utilized chiral ligand and auxiliary for diverse asymmetric syntheses. The unchallenged success of BINOL and its derivatives in the field of transition metal-catalyzed asymmetric reactions or C-C bond forming reactions promoted worldwide an advancement of organic synthesis. The first synthesis of BINOL as racemate was described in 1873. Since then there have been found numerous efficient methods of racemic or enantiomerically pure BINOL preparation and its derivatization. In order to present a brief overview of the most convenient and facile routes to obtain racemic and nonracemic symmetrically substituted 1,1’-binaphthyls based on stoichiometric and catalytic oxidative coupling, classical optical resolution, kinetic enzymatic resolution of racemic mixture or regioselective modification of the binaphthol scaffold the following article is presented.
Źródło:
Wiadomości Chemiczne; 2012, 66, 5-6; 485-528
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2,2’-dihydroksy-1,1’-binaftyl (BINOL) i jego pochodne. Wybrane syntezy i zastosowanie. Część. II
2,2’-dihydroxy-1,1’-binaphthyl (BINOL) and its derivatives : selected synthesis methods and applications. Part II
Autorzy:
Krasowska, D.
Powiązania:
https://bibliotekanauki.pl/articles/172097.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
BINOL
atropoizomery
utleniające sprzęganie
enancjoselektywna synteza
chiralne ligandy
atropoisomers
oxidative coupling
optical resolution
enantioselective synthesis
chiral ligands
Opis:
An invention of new catalytic strategies for stereoselective synthesis is of current interest to many laboratories worldwide . Over the past few decades a remark - able progress in the field of stereocontrolled synthesis has been achieved with chiral 1,1’-binaphthyl compounds. Optically active 1,1’-binaphthyl-2,2’-diol (BINOL) and its derivatives due to their axial dissymmetry and molecular flexibility have been widely utilized as chiral ligands and auxiliaries in stoichiometric or catalytic asymmetric reactions, such as metal-catalysed transformations and enantioselective organocatalysis. BINOL and its functionalized analogues have demonstrated remark - able chiral discrimination properties. Extensive studies on molecular recognition provided the successful results in the application of BINOL as a host for an optical resolution of racemic guests and as a chiral NMR shift reagent for the determination of chiral compounds. It has been found that the axial chirality of binaphthyl units in host molecules is crucial contribution to their stereoselctive complexation with chiral guests.
Źródło:
Wiadomości Chemiczne; 2013, 67, 1-2; 55-92
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient, low-cost optical coupling mechanism for TiO2-SiO2 sol-gel derived slab waveguide surface grating coupler sensors
Autorzy:
Kaźmierczak, Andrzej
Słowikowski, Mateusz
Pavłov, Krystian
Filipiak, Maciej
Vervaeke, Michael
Tyszkiewicz, Cuma
Ottevaere, Heidi
Piramidowicz, Ryszard
Karasiński, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/1835968.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
polymer microlens
optical coupling
surface grating coupler
Opis:
We present an optical signal coupling scheme for slab waveguide surface grating coupler sensors. The proposed solution is based on the use of polymer microlenses. In this work we analyze two types of compact polymer lenses: the aspheric plano-convex lenses and Fresnel lenses. The feasibility of the proposed scheme is demonstrated by the experimental investigation into the optical signal coupling to the test structure of TiO2-SiO2 slab waveguide surface grating coupler using both types of lenses.
Źródło:
Optica Applicata; 2020, 50, 4; 539-549
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Extraordinary optical transmission and vortex excitation by periodic arrays of Fresnel zone plates
Autorzy:
Roszkiewicz, A.
Nasalski, W.
Powiązania:
https://bibliotekanauki.pl/articles/202304.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Fresnel zone plates
focusing
cross-polarisation coupling
optical vortices
Opis:
Extraordinary optical transmission and good focusing properties of a two-dimensional scattering structure is presented. The structure is made of Fresnel zone plates periodically arranged along two orthogonal directions. Each plate consists of two ring-shaped waveguides supporting modes that match the symmetry of a circularly polarized incident plane wave. High field concentration at the focal plane is obtained with the short transverse and long longitudinal foci diameters. Optical vortex excitation in a paraxial region of the transmitted field is also observed and analysed in terms of cross-polarisation coupling. The structure presented may appear useful in visualization, trapping and precise manipulations of nanoparticles.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 855-861
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hiperwalentne związki siarki , selenu i telluru. Część 3. Sulfuran Martina , sulfurany 10-S-5 i 12-S-6
Hypervalent compounds of sulfur, selenium and tellurium. Part 3. Martin su lfurane , sulfuranes 10-S-5 and 12-S-6
Autorzy:
Zając, A.
Powiązania:
https://bibliotekanauki.pl/articles/171640.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
hiperwalentność
wiązanie 3c-4e
sulfuran
persulfuran
sulfuran Martina
bipiramida trygonalna
bipiramida tetragonalna
synteza
chiralność
aktywność optyczna
izomeryzacja
sprzęganie ligandów
hypervalency
3c-4e bond
sulfurane
persulfurane
Martin sulfurane
trigonal bipyramid
tetragonal bipyramid
synthesis
chirality
optical activity
isomerization
ligand coupling
Opis:
In this part of the review one of the most famous 10-S-4 sulfurane called Martin sulfurane together with sulfuranes 10-S-5 and persulfuranes 12-S-6 will be presented. Martin sulfurane has been well known for a relatively long time but it is still useful in organic synthesis as a dehydrating, coupling and oxidizing agent. Its use in selected substitution reactions will be also described. Next, synthesis and selected properties of sulfuranes 10-S-5, mainly sulfurane oxides, and persulfuranes 12-S-6, will be shown. Besides synthetic methods, the review is focused on the investigations of the stability and isomerization of these types of compounds, which is particularly interesting for persulfuranes, because of the presence of three 3c-4e bonds.
Źródło:
Wiadomości Chemiczne; 2012, 66, 9-10; 893-907
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hiperwalentne związki siarki, selenu i telluru. Część 2. Sulfurany 10-S-3 i 10-S-4
Hypervalent compounds of sulfur, selenium and tellurium. Part 2. Sulfuranes 10-S-3 and 10-S-4
Autorzy:
Zając, A.
Powiązania:
https://bibliotekanauki.pl/articles/172591.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
hiperwalentność
wiązanie 3c-4e
sulfuran
pseudorotacja Berry'ego
bipiramida trygonalna
synteza
chiralność
aktywność optyczna
izomeryzacja
sprzęganie ligandów
wymiana liganda
hypervalency
3c-4e bond
sulfurane
Berry pseudorotation
trigonal bipyramid
synthesis
chirality
optical activity
isomerization
ligand coupling
ligand exchange
Opis:
The compounds presented herein are sulfuranes 10-S-3 and 10-S-4 containing hypervalent sulfur atom. They have been known for a relatively long time. Nevertheless, they, and especially 10-S-4 species, are still of great interest due to their unique properties. The review presents recent approaches to the synthesis of these compounds, their selected structural, physical, chemical, stereochemical and electronic properties and their use as reagents and catalysts in several reaction types. The presence of structures of these types as intermediates, which explains selected reaction mechanisms, will also be shown.
Źródło:
Wiadomości Chemiczne; 2012, 66, 7-8; 593-622
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of coupling effect between a unidirectional air waveguide and two cavities with one-way rotating state
Autorzy:
Gao, Yongfeng
He, Liu
Jiang, Zhen
Zhou, Jun
Shi, Yuejia
Bai, Wenfang
Powiązania:
https://bibliotekanauki.pl/articles/174202.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
waveguide-cavity coupling
magneto-optical photonic crystal
unidirectional air waveguide
one-way rotating state
finite element method
Opis:
In the paper we present an implementation of resonance coupling between a unidirectional air waveguide and two cavities with one-way rotating state in a two-dimensional dielectric photonic crystal and a magneto-optical photonic crystal. We theoretically calculate the dispersion curves of the line defect waveguide and the dispersion curves of waveguide-cavity interaction, respectively. Numerical simulations show that, via waveguide-cavity coupling, a series of interesting resonance phenomena can be generated in the system. By modifying direction of the applied external magnetic field, storing and discharging of photonic energy can be realized. Our work may provide a practical and useful guidance for optical communications.
Źródło:
Optica Applicata; 2020, 50, 1; 49-59
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Realization of optical fibers terminated with ball lenses
Autorzy:
Guzowski, B.
Lisik, Z.
Tosik, G.
Powiązania:
https://bibliotekanauki.pl/articles/200929.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
microlens
coupling
optical fiber
active elements
mikrosoczewki
sprzęganie
światłowód
elementy aktywne
Opis:
In this article the process of realization of ball-lensed optical fibers is described. The implementation of four different types of ball-lensed optical fibers developed in Optical Fibers Techniques Laboratory at Lodz University of Technology is presented. Focal lengths of the presented microlenses, which were obtained in simulations and measurements, are also shown in this paper.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2016, 64, 2; 279-282
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulating the effects of refractive index difference on the coupling efficiency of periodically segmented waveguide mode converter
Autorzy:
Zheng, Yu
He, Hao
Jiang, Lianqiong
Duan, Ji'an
Powiązania:
https://bibliotekanauki.pl/articles/2033880.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coupling efficiency
silica waveguide
planar lightwave circuit
micro-optical waveguide
nano-optical waveguide
Opis:
Efficient coupling of micro/nano-optical waveguides with single-mode fibers is the premise for the efficient operation of the integrated photonic chip, which directly determines its optical performance. In this paper, the design principles of periodically segmented waveguide (PSW) structure used for high-efficiency fiber-chip coupling are proposed, and the effects of refractive index difference Δ on coupling efficiency and structural parameters are studied by simulation. It is found that as the Δ of the PSW increases, the period of the PSW tends to be smaller, and the coupling efficiency decreases continuously, reduced by around 0.673 dB in the range of Δ = 3% to Δ = 7%. Through the analysis of PSW optical mechanisms, it demonstrates that the main reason for the decrease of coupling efficiency is that the transmission loss of the tapered section increases sharply with the increase of Δ. High-Δ PSW is difficult to apply to highly integrated silica optical chips due to the unignorably insertion loss.
Źródło:
Optica Applicata; 2021, 51, 4; 565-577
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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