Investigation of transport behavior in borospherene-based molecular wire for rectification applications

The transport properties of molecular wire comprising of B40 fullerene are investigated by employing density functional theory (DFT) and non-equilibrium green’s function (NEGF) methodology. The quantum transport is evaluated by calculating the density of states, transmission spectra at various bias voltages, molecular energy spectra, HOMO-LUMO gap, current–voltage curve, and transmission pathways. In context to its properties, results show that by increasing the length of molecular wire, the device exhibits rectification ratio and prominent NDR behavior. I–V curve scrutinizes that as the length of wire is increased the curve becomes non-linear. This non-linear behavior is more prominent in the case when the length of wire is increased up to six fullerene cages significant rectification ratio (R.R) and negative differential resistance (NDR) comes into the picture. The excellent negative differential resistance ensures that a device with at least six molecular wires can be used as a tunnel diode. Graphic abstract

Vinyl-fluorene Molecular Wires for Voltage Imaging with Enhanced Sensitivity and Reduced Phototoxicity

<p>Fluorescent voltage indicators are an attractive alternative for studying the electrical activity of excitable cells; however, the development of indicators that are both highly sensitive and low in toxicity over long-term experiments remains a challenge. Previously, we reported a fluorene-based voltage-sensitive fluorophore that exhibits much lower phototoxicity than previous voltage indicators in cardiomyocyte monolayers, but suffers from low sensitivity to membrane potential changes. Here, we report that the addition of a single vinyl spacer in the fluorene molecular wire scaffold improves the voltage sensitivity 1.5- to 3.5-fold over fluorene-based voltage probes. Furthermore, we demonstrate the improved ability of the new vinyl-fluorene VoltageFluors (v-fVFs) to monitor action potential kinetics in both mammalian neurons and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Addition of the vinyl spacer between the aniline donor and fluorene monomer results in indicators that are significantly less phototoxic in cardiomyocyte monolayers. These results demonstrate how structural modification to the voltage sensing domain have a large effect on improving the overall properties of molecular wire-based voltage indicators. </p>

Vinyl-fluorene Molecular Wires for Voltage Imaging with Enhanced Sensitivity and Reduced Phototoxicity

<p>Fluorescent voltage indicators are an attractive alternative for studying the electrical activity of excitable cells; however, the development of indicators that are both highly sensitive and low in toxicity over long-term experiments remains a challenge. Previously, we reported a fluorene-based voltage-sensitive fluorophore that exhibits much lower phototoxicity than previous voltage indicators in cardiomyocyte monolayers, but suffers from low sensitivity to membrane potential changes. Here, we report that the addition of a single vinyl spacer in the fluorene molecular wire scaffold improves the voltage sensitivity 1.5- to 3.5-fold over fluorene-based voltage probes. Furthermore, we demonstrate the improved ability of the new vinyl-fluorene VoltageFluors (v-fVFs) to monitor action potential kinetics in both mammalian neurons and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Addition of the vinyl spacer between the aniline donor and fluorene monomer results in indicators that are significantly less phototoxic in cardiomyocyte monolayers. These results demonstrate how structural modification to the voltage sensing domain have a large effect on improving the overall properties of molecular wire-based voltage indicators. </p>

Calculation of CO adsorption capacity of single iron(II)- porphyrin and related electron transfer behavior by DFT theory

The effect of CO adsorption on the electron transport behavior of single iron(II)-porphyrin molecular wire with sulfur end groups bonded to two gold electrodes isinvestigated using nonequilibrium Green's function formalism combined with firstprinciples density functional theory. The current-voltage characteristics of the singleFe-porphyrin molecular wires with and without CO adsorption are calculated. Theresults demonstrate that Fe-porphyrin molecular wire shows a negative differentialresistance (NDR) at 2.0 V