Synthesis and Fabrication of Aligned Conjugated Polymer Thin Films

2012 ◽  
Vol 706-709 ◽  
pp. 1636-1641 ◽  
Author(s):  
Takashi Hirahara ◽  
Masahiro Yoshizawa-Fujita ◽  
Yuko Takeoka ◽  
Masahiro Rikukawa
Keyword(s):  
Functional Groups ◽  
Thermal Annealing ◽  
Conjugated Polymer ◽  
Polarized Light ◽  
Linear Dichroism ◽  
Side Chains ◽  
Absorption Region ◽  
Linearly Polarized ◽  
Cotton Effects ◽  
External Stimuli

Fluorene-thiophene copolymers having chiral and azobenzene substituents, PAzB4-T, were synthesized by the Pd-catalyzed Suzuki coupling method. We studied the aligning organization of the main chain of PAzB4-T with the activation of the attached functional groups by thermal annealing and photo-annealing processes. Circular dichroism (CD) measurements revealed that the thermally annealed PAzB4-T spin-coated films exhibited bisignate Cotton effects over the absorption regions of the polymer main chains and the azobenzene side chains due to the formation of chiral assemblies. After the photo-annealing process, which means linearly polarized light irradiation accompanied by thermal annealing, the PAzB4-T spin-coated films showed linear dichroism over the absorption region of the main chains, due to the alignment of azobenzene side chains against the electric field of the linearly polarized light. These results suggested that rigid conjugated polymers were successfully aligned by the alignment of functional groups with the external stimuli.

Generation of Circularly Polarized Light of Highly Oriented Poly(P-Phenylene Vinylene)

2000 ◽  
Vol 660 ◽  
Author(s):  
A. Marletta ◽  
D. Gonçalves ◽  
O. N. Oliveira ◽  
R. M. Faria ◽  
F. E. G. Guimarães
Keyword(s):  
Polarized Light ◽  
Linear Dichroism ◽  
Asymmetry Factor ◽  
Phenylene Vinylene ◽  
Lb Films ◽  
Circularly Polarized Light ◽  
Langmuir Blodgett ◽  
Efficient Energy ◽  
Absorption Experiment ◽  
Linearly Polarized

ABSTRACTLangmuir-Blodgett (LB) films of poly(p-phenylene vinylene) (PPV) were prepared using an amphiphilic precursor, where the counterion chloride was partially replaced by a long chain dodecylbenzenesulfonate ion. These LB-PPV films are highly ordered along the dipping direction as demonstrated by linear dichroism experiments using linearly polarized optical absorption and emission. The intensity ratio between emitted light parallel and perpendicular to the dipping direction was ca. 17, which is much higher than the dichroic ratio of 3.6 found in the polarized absorption experiment. These values indicate an efficient energy and/or charge transfer between low conjugated segments (disordered) and highly conjugated (ordered) ones after excitation. In addition, the LB films displayed large circular polarization with an asymmetry factor ge which varies from 0.6 to –0.2 when the sample temperature is increased from 30 to 300 K.

scholarly journals Using UV-Vis. Linear Dichroism to Study the Orientation of Molecular Probes and Biomolecules in Lipidic Membranes

2003 ◽  
Vol 17 (2-3) ◽  
pp. 377-398 ◽  
Author(s):  
M. A. R. B. Castanho ◽  
S. Lopes ◽  
M. Fernandes
Keyword(s):  
Distribution Function ◽  
Polarized Light ◽  
Linear Dichroism ◽  
Molecular Probes ◽  
Model Systems ◽  
Spectroscopic Techniques ◽  
Electronic Transition Moment ◽  
Theoretical Predictions ◽  
Linearly Polarized ◽  
Orientational Distribution

Linear dichroism methodologies are based on the different interaction of molecules with linearly polarized light depending on their orientation. Theoretical predictions are used to conclude on the orientation of selected molecules relative to their neighbours (usually an organized matrix). In the specific case of linear dichroism methodologies applied to data obtained from UV-Vis. spectroscopic techniques, the orientational distribution function of the chromophores' electronic transition moment can be calculated and converted to the molecular axis distribution function. In this paper, the orientation of molecular probes and biomolecules in model systems of biomembranes (lipidic matrixes) is explored and illustrated using common membrane probes (trans-parinaric acid, a cyanine and laurdan) and polyene antibiotics (Amphotericin B and Nystatin). The emphasis is on the technique and methodologies themselves, rather than the scientific impact of the attained distributions. The main addressed items are: (1) How to adapt a common UV-Vis. spectrophotometer and spectrofluorimeter to perform linear dicrhoism experiments?, (2) Sample preparation, and (3) Data analysis (including artefacts corrections).

Specific Futures of Optical Anisotropy in Terbium Iron and Terbium Gallium Garnets

2014 ◽  
Vol 605 ◽  
pp. 553-556
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Anatoly Turiev ◽  
Elena Enaldieva ◽  
Tengiz Butkhuzi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energy Levels ◽  
Strong Dependence ◽  
Polarized Light ◽  
Magnetization Vector ◽  
Linear Dichroism ◽  
Linear Birefringence ◽  
Optical Channels ◽  
Linearly Polarized ◽  
Magnetic Linear Dichroism

We reported magnetooptical properties of Tb3+in single crystals of Tb3Fe5O12and Tb3Ga5O12for ion occupying sites of D2symmetry in the garnets structure. It is shown that in the employed Voigt geometry the magnetic linear birefringence and the dichroism reach values 10-4, and have a strong dependence on the wavelength and a strong anisotropy. The absorption spectra were obtained at temperatures of 30K, 100K using magnetic field up to 25 kOe applied parallel and perpendiculare to the electric vector E linearly polarized light on the7F67F0and7F67F1optical transitions region. The aim of this research was revealing of a role of contributions of exchange interaction and a crystal field in splitting of energy levels of the basic condition7F6ion Tb3+multiplet in Tb ferrite-garnet by studying of character of spectra magnetic linear dichroism (MLD) paramagnetic and ferrimagnetic crystals placed in an external magnetic field. More over, the assumption about nonreciprocity of magnetic linear birefringence (MLB) spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector has been experimentally confirmed. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.

Anisotropy of the Linear Magnetic Birefridence of Europium Iron Garnet

2014 ◽  
Vol 605 ◽  
pp. 548-552
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Anatoly Turiev ◽  
Elena Enaldieva ◽  
Tengiz Butkhuzi ◽  
...  
Keyword(s):  
Single Crystal ◽  
Polarized Light ◽  
Magnetization Vector ◽  
Linear Dichroism ◽  
Linear Birefringence ◽  
Optical Channels ◽  
Iron Garnets ◽  
Linearly Polarized ◽  
Magnetic Linear Dichroism ◽  
Iron Garnet

The results of investigation of magnetic linear birefringence (MLB) and magnetic linear dichroism (MLD) of Eu3Fe5O12(EuIG) iron garnet on7F07F6optical transitions upon variation of the directions of the magnetization vector I relative to the electric vector E linearly polarized light that propagates through single crystal iron garnets are presented. The measurements were made on Eu3Fe5O12single-crystal samples in the form of plates 100 μm thick cut in the (110) and (100) plane at the temperatures T = 82 and in a magnetic field H= 25 kOe. The absorption spectra of the linearly polarized light were studied. It is shown that MLB and dichroism in the region of the7F07F6absorption band reach values 10-3. First experimentally discovered nonreciprocity of MLB spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.

scholarly journals Recognition of Bio-Structural Anisotropy by Polarization Resolved Imaging

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 255
Author(s):  
Eugenio Fazio ◽  
Sidra Batool ◽  
Mehwish Nisar ◽  
Massimo Alonzo ◽  
Fabrizio Frezza
Keyword(s):  
Simple Technique ◽  
Fibre Orientation ◽  
Polarized Light ◽  
Linear Dichroism ◽  
Structural Anisotropy ◽  
Linearly Polarized ◽  
Material Texture ◽  
Industrial Environments

In this paper, we develop a simple technique to identify material texture from far, by using polarization-resolved imaging. Such a technique can be easily implemented into industrial environments, where fast and cheap sensors are required. The technique has been applied to both isotropic references (Teflon bar) and anisotropic samples (wood). By studying the radiance of the samples illuminated by linearly polarized light, different and specific behaviours are identified for both isotropic and anisotropic samples, in terms of multipolar emission and linear dichroism, from which fibre orientation can be resolved.

A Strategy for Thioamide Incorporation During Fmoc Solid-Phase Peptide Synthesis with Robust Stereochemical Integrity

2019 ◽  
Author(s):  
luis camacho III ◽  
Bryan J. Lampkin ◽  
Brett VanVeller
Keyword(s):  
Amino Acid ◽  
Functional Groups ◽  
Peptide Synthesis ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Side Chains ◽  
Amino Acid Side Chains ◽  
Peptide Elongation

We describe a method to protect the sensitive stereochemistry of the thioamide—in analogy to the protection of the functional groups of amino acid side chains—in order to preserve the thioamide moiety during peptide elongation.<br>

scholarly journals Strategies for the Development of pH-Responsive Synthetic Polypeptides and Polymer-Peptide Hybrids: Recent Advancements

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 624
Author(s):  
Cintya Dharmayanti ◽  
Todd A. Gillam ◽  
Manuela Klingler-Hoffmann ◽  
Hugo Albrecht ◽  
Anton Blencowe
Keyword(s):  
Functional Groups ◽  
Hybrid Materials ◽  
Tumour Microenvironment ◽  
The Body ◽  
Supramolecular Interactions ◽  
Biological Interactions ◽  
Ph Responsive ◽  
Form Complex ◽  
Synthetic Polypeptides ◽  
External Stimuli

Synthetic polypeptides and polymer-peptide hybrid materials have been successfully implemented in an array of biomedical applications owing to their biocompatibility, biodegradability and ability to mimic natural proteins. In addition, these materials have the capacity to form complex supramolecular structures, facilitate specific biological interactions, and incorporate a diverse selection of functional groups that can be used as the basis for further synthetic modification. Like conventional synthetic polymers, polypeptide-based materials can be designed to respond to external stimuli (e.g., light and temperature) or changes in the environmental conditions (e.g., redox reactions and pH). In particular, pH-responsive polypeptide-based systems represent an interesting avenue for the preparation of novel drug delivery systems that can exploit physiological or pathological pH variations within the body, such as those that arise in the extracellular tumour microenvironment, intracellularly within endosomes/lysosomes, or during tissue inflammation. Here, we review the significant progress made in advancing pH-responsive polypeptides and polymer-peptide hybrid materials during the last five years, with a particular emphasis on the manipulation of ionisable functional groups, pH-labile linkages, pH-sensitive changes to secondary structure, and supramolecular interactions.

scholarly journals Metasurface of Combined Semicircular Rings with Orthogonal Slit Pairs for Generation of Dual Vector Beams

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1718
Author(s):  
Qian Kong ◽  
Manna Gu ◽  
Xiangyu Zeng ◽  
Rui Sun ◽  
Yuqin Zhang ◽  
...  
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Polarized Light ◽  
Orientation Angle ◽  
Fdtd Simulation ◽  
Dual Vector ◽  
Vector Beams ◽  
Linearly Polarized ◽  
Potential Applications ◽  
Difference Time

Manipulation of multichannel vector beams (VBs) with metasurfaces is an important topic and holds potential applications in information technology. In this paper, we propose a novel metasurface for the generation of dual VBs, which is composed of orthogonal slit pairs arranged on multiple groups of combined semicircular rings (CSRs). A group of CSRs include a right-shifted set and a left-shifted set of semicircular rings, and each set of semicircular rings has two halves of circles with different radii, sharing the same shifted center. Under the illumination of linearly polarized light, the two shifted sets of semicircular rings generate the two VBs at the shifted center positions on the observation plane. The slit units of each set are designed with independent rotation order and initial orientation angle. By adjusting the linear polarization of illumination, both two VBs with their orders and polarization states are independently controlled simultaneously. The principle and design are demonstrated by the finite-difference time domain (FDTD) simulation. The work is of significance for miniatured devices of VB generators and for related applications.

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