Structure–property relationships in conjugated molecules

2001 ◽  
Vol 85 (2-3) ◽  
pp. 190-194 ◽  
Author(s):  
P.L. Burn ◽  
R. Beavington ◽  
M.J. Frampton ◽  
J.N.G. Pillow ◽  
M. Halim ◽  
...  
Keyword(s):  
Structure Property ◽  
Conjugated Molecules ◽  
Structure Property Relationships

When Current Does Not Follow Bonds: Current Density in Saturated Molecules

2019 ◽  
Author(s):  
Anders Jensen ◽  
Marc Hamilton Garner ◽  
Gemma C. Solomon
Keyword(s):  
Spatial Distribution ◽  
Current Density ◽  
Current Flow ◽  
Structure Property ◽  
Conjugated Molecules ◽  
Structure Property Relationships ◽  
Electron Transport Properties ◽  
Current Flows ◽  
Molecular Conductance ◽  
Insight Into

<div> <div> <div> <p>The tools commonly used to understand structure-property relationships in molecular conductance, inter-atomic currents and conductance eigenchannels, generally give us a sense of familiarity, with the chemical bonding framework and molecular orbitals reflected in the current. Here we show that while this picture is true for conjugated molecules, it breaks down in saturated systems. We investigate the current density in saturated chains of alkanes, silanes and germanes and show that the current density does not follow the bonds, but rather the nuclei define the diameter of a pipe through which the current flows. We discuss how this picture of current density can be used to understand details about the electron transport properties of these molecules. Understanding the spatial distribution of current through molecules, rather than simply the magnitude, provides a powerful tool for chemical insight into physical properties of molecules that are related to current flow. </p> </div> </div> </div>

When Current Does Not Follow Bonds: Current Density in Saturated Molecules

2019 ◽  
Author(s):  
Anders Jensen ◽  
Marc Hamilton Garner ◽  
Gemma C. Solomon
Keyword(s):  
Spatial Distribution ◽  
Current Density ◽  
Current Flow ◽  
Structure Property ◽  
Conjugated Molecules ◽  
Structure Property Relationships ◽  
Electron Transport Properties ◽  
Current Flows ◽  
Molecular Conductance ◽  
Insight Into

<div> <div> <div> <p>The tools commonly used to understand structure-property relationships in molecular conductance, inter-atomic currents and conductance eigenchannels, generally give us a sense of familiarity, with the chemical bonding framework and molecular orbitals reflected in the current. Here we show that while this picture is true for conjugated molecules, it breaks down in saturated systems. We investigate the current density in saturated chains of alkanes, silanes and germanes and show that the current density does not follow the bonds, but rather the nuclei define the diameter of a pipe through which the current flows. We discuss how this picture of current density can be used to understand details about the electron transport properties of these molecules. Understanding the spatial distribution of current through molecules, rather than simply the magnitude, provides a powerful tool for chemical insight into physical properties of molecules that are related to current flow. </p> </div> </div> </div>

Carbazole-based linear conjugated molecules: structure–property relationships and device properties

RSC Advances ◽  
2013 ◽  
Vol 3 (34) ◽  
pp. 14722 ◽  
Author(s):  
Vandana Bhalla ◽  
Gopal Singh ◽  
Manoj Kumar ◽  
Charan Singh ◽  
Madhu Rawat ◽  
...  
Keyword(s):  
Structure Property ◽  
Conjugated Molecules ◽  
Structure Property Relationships ◽  
Device Properties

Photonic Properties of Dendrons and Dendrimers Incorporating Bis-(Diphenylphosphino)Diphenylpolyenes

1999 ◽  
Vol 598 ◽  
Author(s):  
L. Madrigal ◽  
K. Kuhl ◽  
C. Spangler
Keyword(s):  
Substituent Effects ◽  
Building Blocks ◽  
Optical Nonlinearity ◽  
Fine Tuning ◽  
Structure Property ◽  
Conjugated Molecules ◽  
Structure Property Relationships ◽  
Peak Broadening ◽  
Electro Optic ◽  
Device Applications

ABSTRACTSubstituent effects are quite important in fine tuning the photonic properties of conjugated molecules. In designing new chromophores, electron-donating or withdrawing substituents affect the electron distribution in the conjugation sequence, and previous studies to establish structure- property relationships have noted that when second row elements replace first row elements in the structure (e.g. S for O in donor groups), large enhancements of both the second and third order optical nonlinearity are observed. However, along with the observed enhancement of the nonlinearity, a red-shift in the absorption spectra occurs, often with peak broadening and tailing. This absorptivity-nonlinearity trade-off has been a constant concern in proposing organic materials for electro-optic device applications. In this presentation we will review our recent activity in designing new chromophores wherein P replaces N in donor groups and dendrimer building blocks, and the consequences and opportunities resulting from the observed large blue shifts in the spectra.

Nonresonant Third-Order Nonlinear Polarizability in Linear Conjugated Molecules

1987 ◽  
Vol 109 ◽  
Author(s):  
S. H. Stevenson ◽  
D. S. Donald ◽  
G. R. Meredith
Keyword(s):  
Structure Property ◽  
Third Order ◽  
Conjugated Molecules ◽  
Third Harmonic ◽  
Molecular Features ◽  
Structure Property Relationships ◽  
Liquid Solutions ◽  
Optical Applications ◽  
Nonlinear Optical Applications ◽  
Nonlinear Polarizability

ABSTRACTCrude pictures relating molecular features and enhancement of nonresonant second-order hyperpolarizability have been known and successfully utilized in selection and preparation of materials for nonlinear-optical applications for over a decade. On the other hand, other than the requirement of “electron delocalization”, such a useful picture does not exist for nonresonant third-order hyperpolarizability. In pursuit of such a picture, and to obtain a better view of the range of hyperpolarizability magnitudes which might be obtainable, simple linear conjugated molecules have been synthesized and characterized. Liquid solutions of these model compounds were studied using recently developed high precision optical third harmonic generation techniques. Results of these characterizations and a new addition to the picture of structure-property relationships are reported.

Structure-property relationships of PE/PP sandwiched films

1987 ◽  
Vol 45 ◽  
pp. 454-455
Author(s):  
J. Petermann ◽  
G. Broza ◽  
U. Rieck ◽  
A. Jaballah ◽  
A. Kawaguchi
Keyword(s):  
Mechanical Tests ◽  
Polymer Materials ◽  
Ionic Crystals ◽  
Structure Property ◽  
Polymer Systems ◽  
Structure Property Relationships ◽  
Oriented Films ◽  
Materials Used ◽  
Polymer Laminates ◽  
Heated Glass

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.

Approaches for TEM imaging of cavitation in toughened nylon

1989 ◽  
Vol 47 ◽  
pp. 352-353
Author(s):  
Barbara A. Wood
Keyword(s):  
Morphological Characteristics ◽  
Structure Property ◽  
Polymer Systems ◽  
Selective Staining ◽  
Structure Property Relationships ◽  
Rubber Toughened ◽  
Shear Yield ◽  
Controversial Topic ◽  
Selection Of ◽  
Diamond Knife

A controversial topic in the study of structure-property relationships of toughened polymer systems is the internal cavitation of toughener particles resulting from damage on impact or tensile deformation.Detailed observations of the influence of morphological characteristics such as particle size distribution on deformation mechanisms such as shear yield and cavitation could provide valuable guidance for selection of processing conditions, but TEM observation of damaged zones presents some experimental difficulties.Previously published TEM images of impact fractured toughened nylon show holes but contrast between matrix and toughener is lacking; other systems investigated have clearly shown cavitated impact modifier particles. In rubber toughened nylon, the physical characteristics of cavitated material differ from undamaged material to the extent that sectioning of heavily damaged regions by cryoultramicrotomy with a diamond knife results in sections of greater than optimum thickness (Figure 1). The detailed morphology is obscured despite selective staining of the rubber phase using the ruthenium trichloride route to ruthenium tetroxide.

Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

2020 ◽  
Author(s):  
Alex Stafford ◽  
Dowon Ahn ◽  
Emily Raulerson ◽  
Kun-You Chung ◽  
Kaihong Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transient Absorption ◽  
Reaction Times ◽  
Infrared Light ◽  
Structure Property ◽  
Light Emitting ◽  
Structure Property Relationships ◽  
Nir Light ◽  
Light Intensities ◽  
Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

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