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Molecular Switches

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (30 November 2014) | Viewed by 28978

Special Issue Editor


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Guest Editor
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
Interests: conventional organic, biological and inorganic chemistry; nuclear magnetic resonance (NMR) spectroscopy

Special Issue Information

Dear Colleagues,

Over the past twenty years, distinctions have become increasingly blurred across the traditional areas of organic, inorganic, physical and theoretical chemistry. This has in some part been due to developments in instrumentation and characterization, which have facilitated the exploration of chemical systems at the molecular level. However developments in physics, biology and engineering have also led to innovation in chemical design and applications across all chemical (and related) disciplines. Research into ‘molecular switches’ is one such exciting area. Reversible access to one of a number of states requires a switch that can be operated by a number of external stimuli. In electronics, switches are responsible for the processing and storage of information, but, increasingly, switches are required to get so much smaller that we are now in the domain of ‘molecular switches’ which can be exploited in molecular recognition and electronics, biological applications, medical therapeutics, materials and supramolecular chemistry, to name only a few topical areas. These switches can vary in complexity from intricate multi-step syntheses designed to respond to very specific conditions, or simple molecules that betray bulk changes in pH, light, current, metal chelation, concentration or temperature. The special issue invites submissions in any area relating to molecular switches which defines the state-of-the-art in their synthesis, characterization and applications. Review articles outlining recent developments in the field are also welcome.

Dr. Nick Bampos
Guest Editor

Manuscript Submission Information

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Keywords

  • molecular switches
  • chemical switches
  • biological switches
  • molecular electronics
  • supramolecular chemistry

Published Papers (4 papers)

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Research

1547 KiB  
Article
Femtosecond Laser Spectroscopy of the Rhodopsin Photochromic Reaction: A Concept for Ultrafast Optical Molecular Switch Creation (Ultrafast Reversible Photoreaction of Rhodopsin)
by Olga Smitienko, Victor Nadtochenko, Tatiana Feldman, Maria Balatskaya, Ivan Shelaev, Fedor Gostev, Oleg Sarkisov and Mikhail Ostrovsky
Molecules 2014, 19(11), 18351-18366; https://doi.org/10.3390/molecules191118351 - 11 Nov 2014
Cited by 14 | Viewed by 6853
Abstract
Ultrafast reverse photoreaction of visual pigment rhodopsin in the femtosecond time range at room temperature is demonstrated. Femtosecond two-pump probe experiments with a time resolution of 25 fs have been performed. The first рump pulse at 500 nm initiated cis-trans photoisomerization of rhodopsin [...] Read more.
Ultrafast reverse photoreaction of visual pigment rhodopsin in the femtosecond time range at room temperature is demonstrated. Femtosecond two-pump probe experiments with a time resolution of 25 fs have been performed. The first рump pulse at 500 nm initiated cis-trans photoisomerization of rhodopsin chromophore, 11-cis retinal, which resulted in the formation of the primary ground-state photoproduct within a mere 200 fs. The second pump pulse at 620 nm with a varying delay of 200 to 3750 fs relative to the first рump pulse, initiated the reverse phototransition of the primary photoproduct to rhodopsin. The results of this photoconversion have been observed on the differential spectra obtained after the action of two pump pulses at a time delay of 100 ps. It was found that optical density decreased at 560 nm in the spectral region of bathorhodopsin absorption and increased at 480 nm, where rhodopsin absorbs. Rhodopsin photoswitching efficiency shows oscillations as a function of the time delay between two рump pulses. The quantum yield of reverse photoreaction initiated by the second pump pulse falls within the range 15% ± 1%. The molecular mechanism of the ultrafast reversible photoreaction of visual pigment rhodopsin may be used as a concept for the development of an ultrafast optical molecular switch. Full article
(This article belongs to the Special Issue Molecular Switches)
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1307 KiB  
Article
Nonlinear Optical Molecular Switches for Alkali Ion Identification
by Aurélie Plaquet, Benoît Champagne and Frédéric Castet
Molecules 2014, 19(7), 10574-10586; https://doi.org/10.3390/molecules190710574 - 21 Jul 2014
Cited by 13 | Viewed by 6314
Abstract
This work demonstrates by means of DFT and ab initio calculations that recognition of alkali cations can be achieved by probing the variations of the second-order nonlinear optical properties along the commutation process in spiropyran/merocyanine systems. Due to the ability of the merocyanine [...] Read more.
This work demonstrates by means of DFT and ab initio calculations that recognition of alkali cations can be achieved by probing the variations of the second-order nonlinear optical properties along the commutation process in spiropyran/merocyanine systems. Due to the ability of the merocyanine isomer to complex metal cations, the switching between the two forms is accompanied by large contrasts in the quadratic hyperpolarizability that strongly depend on the size of the cation in presence. Exploiting the nonlinear optical responses of molecular switches should therefore provide powerful analytical tools for detecting and identifying metal cations in solution. Full article
(This article belongs to the Special Issue Molecular Switches)
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1396 KiB  
Article
Thermodynamics and Kinetics of Guest-Induced Switching between “Basket Handle” Porphyrin Isomers
by Alexander B. C. Deutman, Tim Woltinge, Jan M. M. Smits, René De Gelder, Johannes A. A. W. Elemans, Roeland J. M. Nolte and Alan E. Rowan
Molecules 2014, 19(4), 5278-5300; https://doi.org/10.3390/molecules19045278 - 23 Apr 2014
Cited by 6 | Viewed by 7838
Abstract
The synthesis and switching properties of two “basket handle” porphyrin isomers is described. The cis-oriented meso-phenyl groups of these porphyrins are linked at their ortho-positons via benzocrown-ether-based spacers, which as a result of slow atropisomerization are located either on the [...] Read more.
The synthesis and switching properties of two “basket handle” porphyrin isomers is described. The cis-oriented meso-phenyl groups of these porphyrins are linked at their ortho-positons via benzocrown-ether-based spacers, which as a result of slow atropisomerization are located either on the same side of the porphyrin plane (cis), or on opposite sides (trans). In solution, the cis-linked isomer slowly isomerizes in the direction of the thermodynamically more stable trans-isomer. In the presence of viologen (N,N'-dialkyl-4,4'-bipyridinium) derivatives, which have different affinities for the two isomers, the isomerization equilibrium could be significantly influenced. In addition, the presence of these guests was found to enhance the rate of the switching process, which was suggested to be caused by favorable interactions between the positively charged guest and the crown ethers of the receptor, stabilizing the transition state energies of the isomerization reaction between the two isomers. Full article
(This article belongs to the Special Issue Molecular Switches)
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581 KiB  
Communication
C5-Azobenzene-substituted 2'-Deoxyuridine-containing Oligodeoxynucleotides for Photo-Switching Hybridization
by Shohei Mori, Kunihiko Morihiro and Satoshi Obika
Molecules 2014, 19(4), 5109-5118; https://doi.org/10.3390/molecules19045109 - 22 Apr 2014
Cited by 17 | Viewed by 6721
Abstract
A new photoisomeric nucleoside dUAz bearing an azobenzene group at the C5-position of 2'-deoxyuridine was designed and synthesized. Photoisomerization of dUAz in oligodeoxynucleotides can be achieved rapidly and selectively with 365 nm (forward) and 450 nm (backward) irradiation. Thermal denaturation experiments [...] Read more.
A new photoisomeric nucleoside dUAz bearing an azobenzene group at the C5-position of 2'-deoxyuridine was designed and synthesized. Photoisomerization of dUAz in oligodeoxynucleotides can be achieved rapidly and selectively with 365 nm (forward) and 450 nm (backward) irradiation. Thermal denaturation experiments revealed that dUAz stabilized the duplex in the cis-form and destabilized it in the trans-form with mismatch discrimination ability comparable to thymidine. These results indicate that dUAz could be a powerful material for reversibly manipulating nucleic acid hybridization with spatiotemporal control. Full article
(This article belongs to the Special Issue Molecular Switches)
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