1,3–diyne bridged porphyrin dimers via Cu-catalysis: Synthesis, optical properties and application in fullerene binding

2021 ◽  
pp. 130570
Author(s):  
M. Ravikumar ◽  
C. Farley ◽  
C.M. Drain ◽  
M. Baby Mariyatra ◽  
E.M. Mothi
Keyword(s):  
Optical Properties ◽  
Porphyrin Dimers

Synthesis and optical properties of novel covalent and non-covalent porphyrin dimers

2002 ◽  
Vol 06 (06) ◽  
pp. 382-388 ◽  
Author(s):  
Afaf R. Genady ◽  
Detlef Gabel
Keyword(s):  
Optical Properties ◽  
Absorption Spectra ◽  
Reductive Amination ◽  
Electronic Interaction ◽  
Free Base ◽  
Dicarbonyl Compounds ◽  
Spectral Changes ◽  
Covalently Linked ◽  
Porphyrin Dimers

A new series of porphyrin dimers in different geometry have been synthesized. The reductive amination of dicarbonyl compounds, especially 2,5-hexadione and isophthaldhyde, with porphyrin monomers, α,α,α,α-5-(p-aminophenyl)-10,15,20-tris-(4-tolyl)porphyrin, α,α,α,α- and α,α,β,β-5,10,15,20-tetrakis-(o-aminophenyl)porphyrin in the presence of excess of NaBH 3 CN , afforded novel dimeric single and double bridged dimers of free base porphyrins, covalently linked through aliphatic or aromatic spacers. All the synthesized compounds were characterized by NMR, IR, UV-vis, and MS spectroscopy. Significant spectral changes occurred in the absorption spectra of these covalent porphyrin dimers comparing with that of the reference monomers, indicating strong electronic interaction between the adjacent porphyrin units. The UV-vis spectra showed the presence of another kind of non-covalent aggregation, which was observed at pH = 2.5-3 for some of these synthesized dimers. A similar behavior of association was also detected when α,β,α,β-5,10,15,20-tetrakis-(o-aminophenyl)porphyrin was measured at pH = 3.5 in acetone.

scholarly journals Extended π-conjugated ruthenium zinc–porphyrin complexes with enhanced nonlinear-optical properties

2015 ◽  
Vol 51 (14) ◽  
pp. 2855-2858 ◽  
Author(s):  
Miriam de Torres ◽  
Sergey Semin ◽  
Ilya Razdolski ◽  
Jialiang Xu ◽  
Johannes A. A. W. Elemans ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Nonlinear Optical ◽  
Refractive Indices ◽  
Absorption Coefficients ◽  
Metal Core ◽  
Third Order ◽  
Zinc Porphyrin ◽  
Nonlinear Optical Absorption ◽  
Porphyrin Dimers

Zinc porphyrin dimers and trimers, in which the porphyrins are connected via a ruthenium metal core, exhibit large third-order nonlinear optical absorption coefficients and refractive indices.

Modulation of the optical properties of chiral porphyrin dimers by introducing bridged chiral amide-bonds

2020 ◽  
Vol 25 (01) ◽  
pp. 37-46
Author(s):  
Mingfeng Qin ◽  
Zhen Zhang ◽  
Weihua Zhu ◽  
John Mack ◽  
Rodah C. Soy ◽  
...  
Keyword(s):  
Optical Properties ◽  
Amino Acid ◽  
Electronic Structures ◽  
Anion Radical ◽  
Cd Spectra ◽  
Radical Species ◽  
Amide Bonds ◽  
Band Region ◽  
Porphyrin Dimers

The d/l-enantiomers of a series of three Zn(II)tetraarylporphyrin dimers were synthesized and isolated by incorporating a bridging amide-bonded xanthene moiety at the para-position of one of the meso-aryl rings. The electronic structures and optical properties were modulated by incorporating chiral amino acid moieties into the amide-bonding moieties of the xanthene bridge that contain methyl, tolyl and 2-methylindole substituents. A cofacial dimer was formed in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) resulting in a significant red shift of the B band, due to a relative destabilization of the HOMO, which has large MO coefficients on the pyrrole nitrogens. The sign sequences observed in the B band region of the CD spectra due to the presence of the chiral amino acid moieties were modified due to this change in geometry. Significant CD intensity is also observed in the B band region of the CD spectra of anion radical species during in situ spectroelectrochemical measurements.

Regioselective β-Metalation ofmeso-Phosphanylporphyrins. Structure and Optical Properties of Porphyrin Dimers Linked by Peripherally Fused Phosphametallacycles

2008 ◽  
Vol 130 (14) ◽  
pp. 4588-4589 ◽  
Author(s):  
Yoshihiro Matano ◽  
Kazuaki Matsumoto ◽  
Yoshihide Nakao ◽  
Hidemitsu Uno ◽  
Shigeyoshi Sakaki ◽  
...  
Keyword(s):  
Optical Properties ◽  
Porphyrin Dimers

Design of objective lens for 200-kV high-resolution electron microscopes

1983 ◽  
Vol 41 ◽  
pp. 314-315
Author(s):  
K. Tsuno ◽  
T. Honda ◽  
Y. Harada ◽  
M. Naruse
Keyword(s):  
Optical Properties ◽  
Computer Technology ◽  
Axial Magnetic Field ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Resolution Electron ◽  
Correction Of Astigmatism ◽  
Three Stages ◽  
Electron Microscopes ◽  
Stage 1

Developement of computer technology provides much improvements on electron microscopy, such as simulation of images, reconstruction of images and automatic controll of microscopes (auto-focussing and auto-correction of astigmatism) and design of electron microscope lenses by using a finite element method (FEM). In this investigation, procedures for simulating the optical properties of objective lenses of HREM and the characteristics of the new lens for HREM at 200 kV are described.The process for designing the objective lens is divided into three stages. Stage 1 is the process for estimating the optical properties of the lens. Firstly, calculation by FEM is made for simulating the axial magnetic field distributions Bzc of the lens. Secondly, electron ray trajectory is numerically calculated by using Bzc. And lastly, using Bzc and ray trajectory, spherical and chromatic aberration coefficients Cs and Cc are numerically calculated. Above calculations are repeated by changing the shape of lens until! to find an optimum aberration coefficients.

Optical Properties of HVEM Accelerators

1975 ◽  
Vol 33 ◽  
pp. 180-181
Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc
Keyword(s):  
Optical Properties ◽  
Electron Accelerator ◽  
Systematic Investigation ◽  
Electron Source ◽  
High Brightness ◽  
The Past ◽  
Wide Range ◽  
Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

Differential polarization imaging of sickled cells

1988 ◽  
Vol 46 ◽  
pp. 62-63
Author(s):  
Marcos F. Maestre
Keyword(s):  
Optical Properties ◽  
Theoretical Approach ◽  
Polarized Light ◽  
Polarization Microscopy ◽  
Spectroscopic Techniques ◽  
Polarization Imaging ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Microscopic Scale ◽  
Chiral Structures

Recently we have developed a form of polarization microscopy that forms images using optical properties that have previously been limited to macroscopic samples. This has given us a new window into the distribution of structure on a microscopic scale. We have coined the name differential polarization microscopy to identify the images obtained that are due to certain polarization dependent effects. Differential polarization microscopy has its origins in various spectroscopic techniques that have been used to study longer range structures in solution as well as solids. The differential scattering of circularly polarized light has been shown to be dependent on the long range chiral order, both theoretically and experimentally. The same theoretical approach was used to show that images due to differential scattering of circularly polarized light will give images dependent on chiral structures. With large helices (greater than the wavelength of light) the pitch and radius of the helix could be measured directly from these images.

A transmission electron microscopic study of structural transitions in fast ionic conductors

1987 ◽  
Vol 45 ◽  
pp. 156-157
Author(s):  
R. B. Queenan ◽  
P. K. Davies
Keyword(s):  
Optical Properties ◽  
Ionic Conduction ◽  
Recent Observation ◽  
Ionic Conductivities ◽  
Sodium Aluminate ◽  
Two Dimensions ◽  
Ionic Conductors ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Trivalent Cations

Na ß“-alumina (Na1.67Mg67Al10.33O17) is a non-stoichiometric sodium aluminate which exhibits fast ionic conduction of the Na+ ions in two dimensions. The Na+ ions can be exchanged with a variety of mono-, di-, and trivalent cations. The resulting exchanged materials also show high ionic conductivities.Considerable interest in the Na+-Nd3+-ß“-aluminas has been generated as a result of the recent observation of lasing in the pulsed and cw modes. A recent TEM investigation on a 100% exchanged Nd ß“-alumina sample found evidence for the intergrowth of two different structure types. Microdiffraction revealed an ordered phase coexisting with an apparently disordered phase, in which the cations are completely randomized in two dimensions. If an order-disorder transition is present then the cooling rates would be expected to affect the microstructures of these materials which may in turn affect the optical properties. The purpose of this work was to investigate the affect of thermal treatments upon the micro-structural and optical properties of these materials.

Practical Correction of Three Fold Astigmatism in the Philips CM TEM

1996 ◽  
Vol 54 ◽  
pp. 418-419
Author(s):  
Arno J. Bleeker ◽  
Mark H.F. Overwijk ◽  
Max T. Otten
Keyword(s):  
Optical Properties ◽  
Phase Contrast ◽  
The Other ◽  
Objective Lens ◽  
Symmetric Part ◽  
A Posteriori ◽  
Contrast Transfer Function ◽  
High Brightness ◽  
Rotationally Symmetric ◽  
Brightness Field

With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.

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