Search results for "Linea"
showing 10 items of 7724 documents
Second-order NLO main-chain polymers by polymerization of poled monomers
1993
A new method of preparing oriented NLO main chain polymers is presented. We synthesized NLO-monomers that consist of donor acceptor substituted tolane molecules that can be poled in the low molar mass state. In the oriented polar state these monomers can be chemically linked using a thermally activated polyaddition reaction. This reaction links the donor head of one monomer to the acceptor tail of the next hibiting bulk noncentrosymmetry with the average direction of the molecular dipoles parallel to the aligning field.
<title>Nonlinear optical properties of some indandione-1,3 pyridinium betaine derivatives</title>
1997
In this paper nonlinear optical properties of indandione-1,3 pyridinium betaine (IPB) molecule and its novel amphiphilic derivatives have been studied. Hyper-Rayleigh scattering (HRS) has been used as a direct and accurate tool to determine effective hyperpolarizability (beta) of IPB derivatives dissolved in chloroform. Evaluation of hyperpolarizability gives an averaged values of (beta) from 140 multiplied by 10-30 to 450 multiplied by 10-30 esu. Disordering of molecular orientation for multilayer Langmuir-Blodgett films of compound C17-IPB has been studied by SHG techniques and discussed for different film thickness. It has been observed that orientation degree of the Z-type molecular str…
ChemInform Abstract: Preparation and Nonlinear Optics of Monodisperse Oligo(1,4-phenyleneethynylene)s.
2010
Oligo(1,4-phenyleneethynylene)s 1a−e, with solubilizing propoxy side chains, were prepared by use of Hagihara−Sonogashira coupling reactions. The synthetic strategy was based on a building block system and on the use of trimethylsilyl and triisopropylsilyl protecting groups that could be cleaved selectively. The extension of the conjugation with an increasing number of repeat units provokes a bathochromic shift of the long wavelength absorption and a superlinear increase of the second hyperpolarizability |γ|. The corresponding third harmonic generation (THG) measurements were performed using polystyrene matrices and variable laser wavelengths. We conclude that the conjugation length is much…
An improved molecular design of obtaining NLO active molecular glasses using triphenyl moieties as amorphous phase formation enhancers
2012
New molecular design of obtaining molecular glasses has been developed by linking triphenylmethyl moieties to chromophore core by flexible C-C bridge. Compounds capable of forming stable amorphous phase with good optical quality have been acquired with increased chemical and thermal sustainability compared to the previously reported design. NLO activity of compounds has been measured after corona discharge polling. Compared to previously synthesized trityloxy fragment containing compounds increase of d 33 coefficient by up to 17 times was achieved for the same chromophore core containing compounds.
Macrocycles as Molecular Units to Build up Electroresponsive Materials: A Comparative Theoretical Investigation of the Electronic and Optical Propert…
1990
Besides their classical and well-known applications as, e.g., dyes, pigments, catalysts, etc. [1], phthalocyanines (Pc’s) have been of particular interest in many fields of basic and applied research concerning solar cells [2], photosensitizers [3], low dimensional metals [4], gas sensors [5], electrochromism [6], Langmuir-Blodgett (LB) films [7], and nonlinear optics [8]. As an example, gas sensors [9], electronic devices [10], laser recording materials [11], and photovoltaic cells [12] can now be built from LB films of phthalocyanines. This great variety of interesting applications results from a number of unique properties that phthalocyanines exhibit On the one hand, they show an except…
Prediction of Indices of Refraction and Glass Transition Temperatures of Linear Polymers by Using Graph Theoretical Indices
2002
Graph theoretical indices were exclusively used in the prediction of indices of refraction, n, and glass transition temperatures, Tg, into a group of addition polymers. Models with 10 variables were selected for the prediction of n (r = 0.981, SEE = 0.0147) and Tg/M (r = 0.946, SEE = 0.439). The average errors in the predictions were 0.69% and 12.7% for n and Tg, respectively. The descriptors involved in these models were calculated from the structures of the monomers.
Random quasi-phase-matched second harmonic generation in periodically poled lithium tantalate
2009
We experimentally observed and explained bulk second harmonic generation via random quasi-phase-matching, derived from a periodically poled lithium tantalate sample with a randomly patterned mark-to-space-ratio.
Simple models for nonlinear states of double-helix DNA
2006
Review type introduction is given to the simple modeling of DNA. Intrinsically simple modeling aims at understanding or explaining of some “core” phenomena, not giving any all-embracing model of the underlying system. As a consequence the amount of this type of models and their versions is large. Here we have restricted our contemplation to the most important lines in the path of theoretical understanding of DNA melting or denaturation which is one of the important phases occurring during DNAs replication and transcription processes. The model “line” initiated by Peyrard and Bishop shows the richness these simple models can have.
Application of Molecular Topology to the Prediction of the Reaction Yield and Anticancer Activity of Imidazole and Guanidine Derivatives
2013
In this study molecular topology based QSAR has been applied to predict the reaction yield and anticancer activity of 18 imidazole and guanidine derivatives. Four properties were evaluated, namely reaction yield, anti prostatic-cancer activity, anti breast-cancer activity and anti lung-cancer activity. The four models have been validated by both internal and cross validation, and also by randomness tests. The results obtained are in full agreement with the experimental results and confirm the precision, accuracy and robustness of the method followed. After carrying out a virtual screening upon such models, new imidazole and guanidine derivatives with potential anticancer activity are propos…