Molecular Photochemionics (original) (raw)
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Towards molecular photochemionics
International Journal of Photoenergy, 2004
In the last few years there has been a great interest in developing electronics at a molecular level (molecular electronics), e.g. to construct miniaturized electric circuits that would be much smaller than the corresponding micron-scale digital logic circuits fabricated on conventional solid-state semiconductor chips. An alternative possibility to the use of electron fluxes as a means for information processing (electronics) is that of using optical beams (photonics), but up until now scarce attention has been devoted to the possibility of developing photonics at the molecular level. In this paper we review some recent achievements in the design and construction of molecular-level systems that are capable of transferring, switching, collecting, storing, and elaborating light signals. The combination of molecular photonics with chemionics can lead to a wealth of molecular-level devices capable of information processing.
ChemistrySelect, 2018
Carbazole (CZ) can act as a photo‐switch leading to a multifunctional logic system when triggered by fluoride (F–) ions, H2O and light, through efficient interaction of the pyrrole unit with the anions. Here we are reporting a unimolecular platform of CZ (and case specific CZ‐F–) that can be configured as NOT, YES, complimentary IMPLICATION and INHIBIT, a new complex logic gate performing IF‐THEN and NOT operations and a memory element with cyclic “Erase‐Read‐Write‐Read” ability with feedback loop mechanism. The fluorescence responses of the CZ system also have been exploited to design a potential highly secured molecular keypad lock operating with a purely opto‐chemical password composed with optical and chemical input keys. The system displays the applications of light responsive molecules as multifunctional, reconfigurable molecular logic devices that may lead towards true molecular information processing units.
Photochemical characterization of biomimetic molecular switches
Tetrahedron, 2011
The performance of fluorenylideneepyrroline (FPs) and N-alkylated fluorenylideneepyrroline (NAFPs) derivatives for their use as light-driven molecular switches has been studied. Both types of compounds share fast and controllable photoisomerization. Other competitive reaction pathways that could lead to low efficiency have been considered. Only weak fluorescence was measured and high photostability was found when irradiating these compounds for long times, together with high photoisomerization quantum yields. NAFPs are capable of using visible light, which could be useful for practical applications.
Theoretical Chemistry Accounts, 2007
In recent years, computational photochemistry has become a valid tool for the investigation of photophysical properties and photochemical reaction mechanisms in organic chromophores. Theoretical chemists can now adapt their tools to the subject under investigation and to the type and accuracy of the desired information. Different computational strategies can now be adopted to characterize different aspects of the photoinduced molecular reactivity of a given chromophore and to provide, in principle, a quite detailed description of the reactive process from energy absorption to photoproducts formation. A basic aim is to establish a correlation between the structure of the molecule and its photochemical outcome, and, in particular, to assess the effect of modifications of the chromophore and of the molecular environment. In this perspective recent advances and applications of photoinduced cis trans isomerizations involving some organic chromophores active in biologically or technologically relevant problems is reviewed here and discussed in the light of new results. In particular, the photochemistry of azobenzene, retinals and of the green fluorescent protein chromophore is considered, taking into account structural changes and environment effects. The results presented in this work are intended to be a first step toward the design of chromophores that can act as molecular photoswitches.
All-Photonic Multifunctional Molecular Logic Device
Journal of the American Chemical Society, 2011
Photochromes are photoswitchable, bistable chromophores which, like transistors, can implement binary logic operations. When several photochromes are combined in one molecule, interactions between them such as energy and electron transfer allow design of simple Boolean logic gates and more complex logic devices with all-photonic inputs and outputs. Selective isomerization of individual photochromes can be achieved using light of different wavelengths, and logic outputs can employ absorption and emission properties at different wavelengths, thus allowing a single molecular species to perform several different functions, even simultaneously. Here, we report a molecule consisting of three linked photochromes that can be configured as AND, XOR, INH, half-adder, half-subtractor, multiplexer, demultiplexer, encoder, decoder, keypad lock, and logically reversible transfer gate logic devices, all with a common initial state. The system demonstrates the advantages of light-responsive molecules as multifunctional, reconfigurable nanoscale logic devices that represent an approach to true molecular information processing units.
Chemistry – A European Journal, 2011
Photochromic spiropyrans modified with fluorophores were investigated as molecular platforms for the realization of fluorescence switching through modulation of energy transfer. The dyads have been designed such that energy transfer is only observed for the open forms (merocyanine and protonated merocyanine) of the photochrome, while the closed spiropyran is inactive as energy acceptor. This was possible by intentionally choosing fluorophores (4-amino-1,8-naphthalimide, dansyl, and perylene), which lead to a zero spectral overlap with the spiro form and considerable overlap for the merocyanine forms. Based on the Förster theory, energy transfer is predicted to be highly efficient and in some cases of unit efficiency. The combined switching by photonic (light of λ > 530 nm) and chemical (base) inputs enabled the realization of a sequential logic device, which is the basic element of a keypad lock. Furthermore, in combination with an anthracene-based acidochromic fluorescence switch, a reversible logic device was designed. The latter enables the unambiguous coding of different input combinations through multicolour fluorescence signalling. All devices can be conveniently reset to their initial state and repeatedly cycled.