0000000000968583
AUTHOR
Sandeep Kumar
Electronic coupling responsible for energy transfer in columnar liquid crystals
Electronic coupling is the driving force for energy transfer in molecular materials and consists of several components. We determine the strength of dipolarrmultipolar coupling and coupling due to orbital overlap for excitation transport in triphenylene columnar liquid crystals. We use time-resolved fluorescence spectroscopy and computer simulations. The fit of the experimental and simulated fluorescence decays reveals that the transfer process is dominated by short range interactions .multipolar and orbital overlap but the contribution of long range dipolar interactions cannot be neglected. q 1999 Elsevier Science B.V. All rights reserved.
Synthesis and Characterization of Fluorescent, Low-Symmetry Triphenylene Discotic Liquid Crystals: Tailoring of Mesomorphic and Optical Properties
A series of monofunctionalized triphenylene-based discotic liquid crystals were synthesized starting from 2-hydroxy-3,6,7,10,11-pentakis(pentyloxy)triphenylene. These compounds are unique in that they possess a single electron-withdrawing group (and consequently a large dipole moment) connected directly to the polyaromatic core. All of the new liquid crystals show a significantly broader range of mesogenicity relative to the parent compound 2,3,6,7,10,11-hexakis(pentyloxy)triphenylene. Moreover, some of the new mesogens exhibit a more ordered mesophase relative to the hexagonal columnar phase (Dh) at lower temperatures. Monofunctionalization of the triphenylene core has a dramatic effect on…
PMT: New analytical framework for automated evaluation of geo-environmental modelling approaches
Geospatial computation, data transformation to a relevant statistical software, and step-wise quantitative performance assessment can be cumbersome, especially when considering that the entire modelling procedure is repeatedly interrupted by several input/output steps, and the self-consistency and self-adaptive response to the modelled data and the features therein are lost while handling the data from different kinds of working environments. To date, an automated and a comprehensive validation system, which includes both the cutoff-dependent and –independent evaluation criteria for spatial modelling approaches, has not yet been developed for GIS based methodologies. This study, for the fir…
UInDeSI4.0 : An efficient Unsupervised Intrusion Detection System for network traffic flow in Industry 4.0 ecosystem
In an Industry 4.0 ecosystem, all the essential components are digitally interconnected, and automation is integrated for higher productivity. However, it invites the risk of increasing cyber-attacks amid the current cyber explosion. The identification and monitoring of these malicious cyber-attacks and intrusions need efficient threat intelligence techniques or intrusion detection systems (IDSs). Reducing the false positive rate in detecting cyber threats is an important step for a safer and reliable environment in any industrial ecosystem. Available approaches for intrusion detection often suffer from high computational costs due to large number of feature instances. Therefore, this paper…
Scanning tunneling microscopy investigation of tricycloquinazoline liquid crystals on gold
Self-assembled monolayers (SAMs) of hexaalkylthioether derivatives of tricycloquinazoline (TCQ) on Au(111) and tungsten diselenide (WSe2) were investigated by scanning tunneling microscopy (STM). The Au(111) surfaces were found to be etched by the thioether containing solutions. Corroded surfaces which are similar to gold surfaces that were coated with SAMs of thiols or disulfides were revealed by STM. Atomic adsorption spectroscopy proved that an amount of gold that corresponds to ca. 30% of a monolayer was dissolved in the assembly solutions. On gold, the aromatic cores of the molecules were found to be in face-on orientation. The alkyl substituents were in most cases folded upwards and s…
Synthesis of New Functionalized Discotic Liquid Crystals for Photoconducting Aplications
Abstract The columnar structure of discotic liquid crystals has been shown to be well suited for electronic transport parallel to the columnar axis. To tailor the processibility and mesophase behavior of such materials, several hydroxytriphenylene derivatives were synthesized. These hydroxytriphenylenes can be converted into oligomers, networks or polymers. Further, they can be reduced to arenes which posses reactive sites for classical aromatic substitutions. A number of mixed tail triphenylene derivatives and fluorescent, low symmetry triphenylene discotic liquid crystals were synthesized and characterized.