Photodetectors fabricated from a self-assembly of a deoxyguanosine derivative

A metal–semiconductor–metal (MSM) photodetector has been fabricated using as the semiconductor, a self-assembled layer of a DNA basis, namely a deoxyguanosine derivative, deposited between two gold electrodes. These were defined lithographically on a SiO2 substrate, separated by a distance of about 120 nm. The resulting self-assembled guanosine crystal has been deposited in such a way to achieve striking semiconducting properties. We show that with these conditions, the I–V characteristics are independent of the crystal orientation. The device shows a high current response (differential resistance at room temperature ranges in MΩ) which is symmetric with respect to bias sign and dependent on the illumination conditions. This behavior can be explained by taking into account the standard MSM theory and its applications as a photodetector

Transistors based on the Guanosine molecule (a DNA base)

Abstract Molecules are attractive to develop nano-electronic devices. In this paper a new type of transistor is realized by using self-organized films of the Guanosine molecule, a modified DNA base. With its 40 nm channel length the transistor is a good starting point for a new class of nano-electronics devices. Experimental current-voltage characteristics are shown. A circuital model is also proposed

Field Effect Transistor Based on a Modified DNA Base

In this work, a field effect transistor based on a deoxyguanosine derivative (a DNA base) is demonstrated. Our experiments on transport through the source and drain electrodes interconnected by self-assembled guanine ribbons (Gottarelli et al. Helv. Chim. Acta 1998, 81, 2078; Gottarelli et al. Chem. Eur. J. 2000, 6, 3242; Giorgi et al. Chem Eur. J. 2002, 8, 2143) suggest that these devices behave like p-channel MOSFETs, The devices exhibit a maximum voltage gain of 0.76. This prototype transistor represents a starting point toward the development of biomolecular electronic devices

Hybrid molecular electronic (HME) transistor based on deoxyguanosine derivatives

In this work, a field effect transistor based on deoxyguanosine derivatives (a DNA basis) is demonstrated by means of systematic transport experiments. Our nanodevices were fabricated starting from a deoxyguanosine derivative (dG(C-10)(2)) layer interconnecting planar nano-electrodes, with separation in the 20-40nm range. The three terminal devices exhibit a maximum voltage gain of 0.76. Though the quick aging and the reproducibility of the devices have to be improved, the realization of a transistor-like device represents a starting point towards the development of planar solid-state bio-molecular electronic devices

Exciton Optical Activity of Molecules Containing Three and Six Coupled Oscillators Belonging to C3 and D3 Point Groups: Applications to Cyclotriveratrylenes and Cryptophanes

The exciton model of optical activity has been applied to C3 cyclotriveratrylenes and D3 cryptophanes, molecules containing three and six coupled oscillators, respectively. Using this model, in conjunction with Platt\u27s spectroscopic moment approach, very good agreement has been established between experimental and calculated spectra. These results point to the importance of the exciton model in explaining the CD spectra of molecules containing more than two oscillators

THE CONTROL OF THE CHOLESTERIC PITCH BY SOME AZO PHOTOCHEMICAL CHIRAL SWITCHES

A few chiral azo compounds, which undergo reversible photochemical switching, are presented. Of these, the most interesting contain the binaphthyl moiety and belong to the C-2 (derivatives 1 and 2) or C-1 symmetry group (derivatives 3 and 4). These binaphthyl compounds display intense CD and high values. Photochemical switching has profound effects on both the CD and values of these compounds; in the case of compound 3, the sign of beta changes upon isomerisation. Compound 2 has, to our knowledge, the highest P of the switches reported in the literature and also seems the most interesting owing to its fast response to photochemical stimuli. Nematic phases can be transformed into cholesteric phases with reflection bands in the visible region by doping with reasonable amounts of 1 and 2. The reflection colours can be changed reversibly by photoisomerisation of the switches. Thermal reversion of the colourless UV photostationary state to the green isomeric EE state or to intermediate coloured states is temperature dependent. This can allow the thermal history of a sample to be traced