Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

?-Bond Electron Delocalization in Oligosilanes as Function of Substitution Pattern, Chain Length, and Spatial Orientation.

ABSTRACT: Polysilanes are known to exhibit the interesting property of ?-bond electron delocalization. By employing optical spectroscopy (UV-vis), it is possible to judge the degree of delocalization and also differentiate parts of the molecules which are conjugated or not. The current study compares oligosilanes of similar chain length but different substitution pattern. The size of the substituents determines the spatial orientation of the main chain and also controls the conformational flexibility. The chemical nature of the substituents affects the orbital energies of the molecules and thus the positions of the absorption bands.

SUBMITTER: Hlina J

PROVIDER: S-EPMC6273834 | biostudies-other | 2016 Aug

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Publications

σ-Bond Electron Delocalization in Oligosilanes as Function of Substitution Pattern, Chain Length, and Spatial Orientation.

Hlina Johann J Stella Filippo F Aghazadeh Meshgi Mohammad M Marschner Christoph C Baumgartner Judith J

Molecules (Basel, Switzerland) 20160818 8

Polysilanes are known to exhibit the interesting property of σ-bond electron delocalization. By employing optical spectroscopy (UV-vis), it is possible to judge the degree of delocalization and also differentiate parts of the molecules which are conjugated or not. The current study compares oligosilanes of similar chain length but different substitution pattern. The size of the substituents determines the spatial orientation of the main chain and also controls the conformational flexibility. The ...[more]

PMID: 27548126

Similar Datasets

Extreme electron polaron spatial delocalization in ?-conjugated materials.

Project description:The electron polaron, a spin-1/2 excitation, is the fundamental negative charge carrier in ?-conjugated organic materials. Large polaron spatial dimensions result from weak electron-lattice coupling and thus identify materials with unusually low barriers for the charge transfer reactions that are central to electronic device applications. Here we demonstrate electron polarons in ?-conjugated multiporphyrin arrays that feature vast areal delocalization. This finding is evidenced by concurrent optical and electron spin resonance measurements, coupled with electronic structure calculations that suggest atypically small reorganization energies for one-electron reduction of these materials. Because the electron polaron dimension can be linked to key performance metrics in organic photovoltaics, light-emitting diodes, and a host of other devices, these findings identify conjugated materials with exceptional optical, electronic, and spintronic properties.

| S-EPMC4653201 | biostudies-literature

σ-Bond electron delocalization of branched oligogermanes and germanium containing oligosilanes.

Project description:In order to evaluate the influence of germanium atoms in oligo- and polysilanes, a number of oligosilane compounds were prepared where two or more silicon atoms were replaced by germanium. While it can be expected that the structural features of thus altered molecules do not change much, the more interesting question is, whether this modification would have a profound influence on the electronic structure, in particular on the property of σ-bond electron delocalization. The UV-spectroscopic comparison of the oligosilanes with germanium enriched oligosilanes and also with oligogermanes showed a remarkable uniform picture. The expected bathochromic shift for oligogermanes and Ge-enriched oligosilanes was observed but its extent was very small. For the low energy absorption band the bathochromic shift from a hexasilane chain (256 nm) to a hexagermane chain with identical substituent patterns (259 nm) amounts to a mere 3 nm.

| S-EPMC4236089 | biostudies-literature

Impact of Substitution Pattern and Chain Length on the Thermotropic Properties of Alkoxy-Substituted Triphenyl-Tristriazolotriazines.

Project description:Tristriazolotriazines (TTTs) with a threefold alkoxyphenyl substitution were prepared and studied by DSC, polarized optical microscopy (POM) and X-ray scattering. Six pentyloxy chains are sufficient to induce liquid-crystalline behavior in these star-shaped compounds. Thermotropic properties of TTTs with varying substitution patterns and a periphery of linear chains of different lengths, branching in the chain and swallow-tails, are compared. Generally, these disks display broad and stable thermotropic mesophases, with the tangential TTT being superior to the radial isomer. The structure-property relationships of the number of alkyl chains, their position, length and structure were studied.

| S-EPMC7729490 | biostudies-literature

Spatial Regulation Dominates Gene Function in the Ganglia Chain

Project description:Spatial regulation analysis across multiple condition comparisons revealed distinct patterns of gene expression. We combined these transcriptome data with spatial CNS data to produce the spatio-transcripto map of the ganglia chain. The Hirudo Medicinalis set of transcripts generated here provides a resource for gene discovery and gene regulation within the nervous system. In addition, the strategy for de novo assembly of transcriptome data presented here may be helpful in other similar transcriptome studies. Examination of 3 different ganglia in 3 different leeches.

2013-12-04 | E-GEOD-45569 | biostudies-arrayexpress

Spatial pattern of cell geometry and cell-division orientation in zebrafish lens epithelium.

Project description:Cell proliferation is a key regulator of tissue morphogenesis. We examined cell proliferation and cell division in zebrafish lens epithelium by visualizing cell-cycle phases and nuclear positions, using fluorescent-labeled geminin and histone proteins. Proliferation was low in the anterior region of lens epithelium and higher in the marginal zone anterior to the equator, suggesting that the proliferation zone, called the germinative zone, is formed in zebrafish lens. Interestingly, cell-division orientation was biased longitudinally in the anterior region, shifted from longitudinal to circumferential along the anterior-posterior axis of lens sphere, and was biased circumferentially in the peripheral region. These data suggest that cell-division orientation is spatially regulated in zebrafish lens epithelium. The Hertwig rule indicates that cells tend to divide along their long axes. Orientation of long axes and cell division were biased similarly in zebrafish lens epithelium, suggesting that cell geometry correlates with cell-division orientation. A cell adhesion molecule, E-cadherin, is expressed in lens epithelium. In a zebrafish e-cadherin mutant, the long axes and cell-division orientation were shifted more longitudinally. These data suggest that E-cadherin is required for the spatial pattern of cell geometry and cell-division orientation in zebrafish lens epithelium.

| S-EPMC4197447 | biostudies-literature

Visualizing electron delocalization in contorted polycyclic aromatic hydrocarbons.

Project description:Electron delocalization in contorted polycyclic aromatic hydrocarbon (PAH) molecules was examined through 3D isotropic magnetic shielding (IMS) contour maps built around the molecules using pseudo-van der Waals surfaces. The resulting maps of electron delocalization provided an intuitive, yet detailed and quantitative evaluation of the aromatic, non aromatic, and antiaromatic character of the local and global conjugated cyclic circuits distributed over the molecules. An attractive pictural feature of the 3D IMS contour maps is that they are reminiscent of the Clar π-sextet model of aromaticity. The difference in delocalization patterns between the two faces of the electron circuits in contorted PAHs was clearly visualized. For π-extended contorted PAHs, some splits of the π system resulted in recognizable patterns typical of smaller PAHs. The differences between the delocalization patterns of diastereomeric chiral PAHs could also be visualized. Mapping IMS on pseudo-van der Waals surfaces around contorted PAHs allowed visualization of their superimposed preferred circuits for electron delocalization and hence their local and global aromaticity patterns.

| S-EPMC8513938 | biostudies-literature

Computational study of electron delocalization in hexaarylbenzenes.

Project description:A number of hexaarylbenzene compounds were studied theoretically, in order to compare energy changes as a result of the toroidal delocalization effect that is characteristic of all these species. The energy was studied taking advantage of locally designed isodesmic reactions. Results indicate that the amount of aromaticity manifested by each substituent is a factor that should be considered when assessing the quantity of energy dissipated from each aromatic center. The influence of different substituents on electronic delocalization is also analyzed, as well as the role played by their frontier molecular orbitals.

| S-EPMC6271654 | biostudies-other

Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease.

Project description:Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss-of-function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bodies (LBs). The leading LD hypothesis that hyperphosphorylation causes the insolubility was recently challenged by the observation that phosphatase-inactive laforin rescues the laforin-deficient LD mouse model, apparently through correction of a general autophagy impairment. We were for the first time able to quantify brain glycogen phosphate. We also measured glycogen content and chain lengths, LBs, and autophagy markers in several laforin- or malin-deficient mouse lines expressing phosphatase-inactive laforin. We find that: (i) in laforin-deficient mice, phosphatase-inactive laforin corrects glycogen chain lengths, and not hyperphosphorylation, which leads to correction of glycogen amounts and prevention of LBs; (ii) in malin-deficient mice, phosphatase-inactive laforin confers no correction; (iii) general impairment of autophagy is not necessary in LD We conclude that laforin's principle function is to control glycogen chain lengths, in a malin-dependent fashion, and that loss of this control underlies LD.

| S-EPMC5494504 | biostudies-literature

Real space electron delocalization, resonance, and aromaticity in chemistry.

Project description:Chemists explaining a molecule's stability and reactivity often refer to the concepts of delocalization, resonance, and aromaticity. Resonance is commonly discussed within valence bond theory as the stabilizing effect of mixing different Lewis structures. Yet, most computational chemists work with delocalized molecular orbitals, which are also usually employed to explain the concept of aromaticity, a ring delocalization in cyclic planar systems which abide certain number rules. However, all three concepts lack a real space definition, that is not reliant on orbitals or specific wave function expansions. Here, we outline a redefinition from first principles: delocalization means that likely electron arrangements are connected via paths of high probability density in the many-electron real space. In this picture, resonance is the consideration of additional electron arrangements, which offer alternative paths. Most notably, the famous 4n + 2 Hückel rule is generalized and derived from nothing but the antisymmetry of fermionic wave functions.

| S-EPMC8355119 | biostudies-literature

Length and orientation constancy learning in 2-dimensions with auditory sensory substitution: the importance of self-initiated movement.

Project description:A subset of sensory substitution (SS) devices translate images into sounds in real time using a portable computer, camera, and headphones. Perceptual constancy is the key to understanding both functional and phenomenological aspects of perception with SS. In particular, constancies enable object externalization, which is critical to the performance of daily tasks such as obstacle avoidance and locating dropped objects. In order to improve daily task performance by the blind, and determine if constancies can be learned with SS, we trained blind (N = 4) and sighted (N = 10) individuals on length and orientation constancy tasks for 8 days at about 1 h per day with an auditory SS device. We found that blind and sighted performance at the constancy tasks significantly improved, and attained constancy performance that was above chance. Furthermore, dynamic interactions with stimuli were critical to constancy learning with the SS device. In particular, improved task learning significantly correlated with the number of spontaneous left-right head-tilting movements while learning length constancy. The improvement from previous head-tilting trials even transferred to a no-head-tilt condition. Therefore, not only can SS learning be improved by encouraging head movement while learning, but head movement may also play an important role in learning constancies in the sighted. In addition, the learning of constancies by the blind and sighted with SS provides evidence that SS may be able to restore vision-like functionality to the blind in daily tasks.

| S-EPMC4469823 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data