Electrical switching and memory phenomena observed in redox-gradient dendrimer sandwich devices

We report on the fabrication of dendrimer sandwich devices with electrical switching and memory properties. The storage media is consisted of a redox-gradient dendrimer layer sandwiched in organic barrier thin films. The dendrimer layer acts as potential well where redox-state changes and consequent electrical transitions of the embedded dendrimer molecules are expected to be effectively triggered and retained, respectively. Experimental results indicated that electrical switching could be reproducibly obtained in such dendrimer sandwiches upon a threshold bias voltage. After switching, the device conductivity could be increased more than three orders of magnitude, which can keep stable for several days in ambient conditions. Our work demonstrates the possibility of using solid-state redox-gradient dendrimer films as hopeful information storage media.Comment: 13 pages, 5 figures, 1 table, unpublished manuscrip

Mechanisms of light energy harvesting in dendrimers and hyperbranched polymers

Since their earliest synthesis, much interest has arisen in the use of dendritic and structurally allied forms of polymer for light energy harvesting, especially as organic adjuncts for solar energy devices. With the facility to accommodate a proliferation of antenna chromophores, such materials can capture and channel light energy with a high degree of efficiency, each polymer unit potentially delivering the energy of one photon-or more, when optical nonlinearity is involved. To ensure the highest efficiency of operation, it is essential to understand the processes responsible for photon capture and channelling of the resulting electronic excitation. Highlighting the latest theoretical advances, this paper reviews the principal mechanisms, which prove to involve a complex interplay of structural, spectroscopic and electrodynamic properties. Designing materials with the capacity to capture and control light energy facilitates applications that now extend from solar energy to medical photonics. © 2011 by the authors; licensee MDPI, Basel, Switzerland

Chiral catenanes and rotaxanes:fundamentals and emerging applications

Molecular chirality provides a key challenge in host-guest recognition and other related chemical applications such as asymmetric catalysis. For a molecule to act as an efficient enantioselective receptor, it requires multi-point interactions between host and chiral guest, which may be achieved by an appropriate chiral 3D scaffold. As a consequence of their interlocked structure, catenanes and rotaxanes may present such a 3D scaffold, and can be chiral by inclusion of a classical chiral element and/or as a consequence of the mechanical bond. This Minireview presents illustrative examples of chiral [2]catenanes and [2]rotaxanes, and discusses where these molecules have been used in chemical applications such as chiral host-guest recognition and asymmetric catalysis

A robust fluorescent chemosensor for aluminium ion detection based on a Schiff base ligand with an azo arm and application in a molecular logic gate

In this present work we have reported the synthesis and structural characterisations of a N2O2 donor Schiff base chemosensor with an azo arm (H2L). Various spectroscopic tools like single crystal X-ray, NMR, UV-vis, FTIR, ESI-mass spectrometry etc. have been deployed to develop the present work. In recent years a number of azo derived chemosensors have been reported by different research groups. This is first time we are reporting the design and properties of an azo derived chemosensor (H2L) for the detection of aluminium ions in semi aqueous medium. It has been found that it selectively senses Al3+ ions in semi aqueous solution. Here, the sensing process is mainly based on a chelation enhanced fluorescence process (CHEF). It has very high selectivity over other metal ions and anions. A detailed literature survey has been carried out and compared with this work. It has an appreciably low detection limit i.e. 6.93 nM. 1H NMR titration was carried out to support the plausible complexation process. 1 : 1 stoichiometry binding between the chemosensor and Al3+ ions has been confirmed from Job's plot. An inhibition molecular logic gate has been constructed using chemosensor (H2L), where Al3+ and EDTA act as inputs and fluorescence emission is the output. The structural and electronic parameters of the chemosensor (H2L) and complex [AL(L)]NO3 have been studied in detail using theoretical tools like DFT and TDDFT

Das Bonner Universitäts-Magazin Forsch berichtet über die Poolforschung

Cover der Frühjahrsausgabe 2020 der Forsch Wir freuen uns sehr, dass mit dem Titel „Serienproduktion in der Antike  – Pilotprojekt: Studierende erforschen Modulare Systeme“ in der Frühjahrsausgabe des Bonner Universitäts-Magazins Forsch ein Bericht über unsere Poolforschung und unser erstes Treffen im vergangenen Februar erschienen ist