| 1. |
- Andreasson, Joakim, 1973, et al.
(författare)
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A molecule-based 1 : 2 digital demultiplexer
- 2007
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:38, s. 14274-14278
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Tidskriftsartikel (refereegranskat)abstract
- A trichromophoric molecule consisting of a porphyrin linked to both a dihydropyrene and a dihydroindolizine-type photochrome, in combination with a third harmonic generating crystal, functions as a 1:2 digital demultiplexer with photonic inputs and outputs. Each of the two photochromes may be cycled independently between two metastable forms, leading to four photoisomers, three of which are used in the demultiplexer. These isomers interact photochemically with the porphyrin in order to yield the demultiplexer function. With the address input (1064-nm light) turned off, one Output of the device (porphyrin fluorescence) tracks the state of the data input (532-nm light). When the address input is turned on, the second output (absorbance at 572 nm) tracks the state of the data input, while the first output remains off. The demultiplexer does not require chemical or electrical inputs, and can cycle through its operational sequences multiple times.
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| 2. |
- Andreasson, Joakim, 1973, et al.
(författare)
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All-photonic molecular half-adder
- 2006
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 128:50, s. 16259-16265
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Tidskriftsartikel (refereegranskat)abstract
- One molecule acts as both an AND and an XOR Boolean logic gate that share the same two photonic inputs. The molecule comprises a half-adder, adding two binary digits with only light as inputs and outputs, and consists of three covalently linked photochromic moieties, a spiropyran and two quinolinederived dihydroindolizines. The AND function is based on the absorption properties of the molecule, whereas the XOR function is based on an off-on-off response of the fluorescence to the inputs that results from interchromophore excited-state quenching interactions. The half-adder is simple to operate and can be cycled many times.
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| 3. |
- Andreasson, Joakim, 1973, et al.
(författare)
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Molecular 2 : 1 digital multiplexer
- 2007
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Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 46:6, s. 958-961
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Tidskriftsartikel (refereegranskat)abstract
- (Chemical Equation Presented) Two into one: A porphyrin linked to two photochromic moieties performs as a 2:1 digital multiplexer (MUX). It takes heat and red light as the two inputs (in 1 and in 2), and a third switchable input (green light, sel) selects whether the output (porphyrin fluorescence) reports the state of in 1 or in 2. Each photochromic moiety may be independently photoisomerized to isomers that quench the porphyrin fluorescence. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.
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| 4. |
- He, J., et al.
(författare)
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Switching of a photochromic molecule on gold electrodes: single-molecule measurements
- 2005
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Ingår i: Nanotechnology. - : IOP Publishing. - 1361-6528 .- 0957-4484. ; 16:6, s. 695-702
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the electronic changes caused by light-induced isomerization of a photochromic molecule between an open state (that absorbs in the UV to become closed) and a closed state (that absorbs in the visible to become open). Data obtained using a newly developed repetitive break junction method are interpreted in terms of single-molecule resistances of 526 +/- 90 M Omega in the open form and 4 +/- 1 M Omega in the closed form when the molecule is bound between two gold contacts via dithiol linkages. The corresponding ratio of open to closed resistance is in close agreement with the results of ab initio calculations, though the measured resistances are about half of the calculated values. Optical spectroscopy indicates that the photoisomerization occurs in both directions on small gold particles, evaporated thin gold films, and in the break junction experiments.
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| 5. |
- Straight, S. D., et al.
(författare)
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Molecular AND and INHIBIT gates based on control of porphyrin fluorescence by photochromes
- 2005
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Ingår i: Journal of the American Chemical Society. ; 127:26, s. 9403-9409
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Tidskriftsartikel (refereegranskat)abstract
- A molecular triad consisting of a porphyrin (P) covalently linked to two photochromes - one from the dihydroindolizine family (DHI) and one from the dihydropyrene family (DHP) - has been synthesized and found to act as either a molecular AND logic gate or an INHIBIT gate, depending on the inputs and initial state of the photochromes. The basis of these functions is quenching of porphyrin fluorescence (output of the gates) by the photochromes. The spiro form of DHI does not quench porphyrin fluorescence, whereas its betaine isomer strongly quenches by photoinduced electron transfer. DHP also quenches porphyrin fluorescence, but its cyclophanediene isomer does not. The triad has been designed using suitable energetics and electronic interactions, so that although these quenching phenomena may be observed, independent isomerization of the attached photochromes still occurs. This makes it possible to switch porphyrin fluorescence on or off by isomerization of the photochromes using various combinations of inputs such as UV light, red light, and heat.
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| 6. |
- Andreasson, Joakim, 1973, et al.
(författare)
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All-Photonic Multifunctional Molecular Logic Device
- 2011
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 133:30, s. 11641-11648
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Andreasson, Joakim, 1973, et al.
(författare)
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An All-Photonic Molecular Keypad Lock
- 2009
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Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 15:16, s. 3936-3939
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Tidskriftsartikel (refereegranskat)abstract
- An all photonic molecular keypad lock with a reset capacity, that is capable of distinguishing one two-digit code out of eight possible combinations were described. The synthesis and characterization of triad 1 with distilled 2-methyltetrahydrofuran as the solvent for spectroscopic measurement were reported, where the samples were degassed by size freeze-pump-thaw cycles to a final pressure. The functional principle of a keypad lock is that it gives an output signal only when given the correct inputs in the correct order, also the capacity of the triad to perform as a two-input PAND gate with reset capacity are considered. The keypad lock is found to be operated by five optical signals in the UV region including fluorescence emission that signals the actual opening of the lock, which can also be used numerous times without ant photodegradation affecting the performance.
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| 8. |
- Andreasson, Joakim, 1973, et al.
(författare)
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Molecular all-photonic encoder-decoder
- 2008
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Ingår i: Journal of the American Chemical Society. ; 130:33, s. 11122-11128
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Tidskriftsartikel (refereegranskat)abstract
- In data processing, an encoder can compress digital information for transmission or storage, whereas a decoder recovers the information in its original form. We report a molecular triad consisting of a dithienylethene covalently linked to two fulgimide photochromes that performs as an all-photonic single-bit 4-to-2 encoder and 2-to-4 decoder. The encoder compresses the information contained in the four inputs into two outputs. The inputs are light of four different wavelengths that photoisomerize the fulgimide, dithienylethene, or both. The outputs are absorbance at two wavelengths. The two decoder inputs are excitation at two wavelengths, whereas the four outputs, which recover the information compressed into the inputs, are absorbance at two wavelengths, transmittance at one wavelength, and fluorescence emission. The molecule can be cycled through numerous encoder and decoder functions without significant photodecomposition. Molecular photonic encoders and decoders could potentially be used for labeling and tracking of nano- and microscale objects as well as for data manipulation.
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| 9. |
- Straight, S. D., et al.
(författare)
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Photochromic control of photoinduced electron transfer. Molecular double-throw switch
- 2005
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Ingår i: Journal of the American Chemical Society. ; 127:8, s. 2717-2724
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Tidskriftsartikel (refereegranskat)abstract
- A molecular double-throw switch that employs a photochromic moiety to direct photoinduced electron transfer from an excited state donor down either of two pathways has been prepared. The molecular triad consists of a free base porphyrin (P) linked to both a C-60 electron acceptor and a dihydroindolizine (DHI) photochrome. Excitation of the porphyrin moiety of DHI-P-C-60 results in photoinduced electron transfer with a time constant of 2.3 ns to give the DHI-P.+-C-60(.-) charge-separated state with a quantum yield of 82%. UV (366 nm) light photoisomerizes the DHI moiety to the betaine (BT) form, which has a higher reduction potential than DHI. Excitation of the porphyrin of BT-P-C-60 is followed by photoinduced electron transfer with a time constant of 56 ps to produce BT.--P.+-C-60 in 99% yield. Isomerization of BT-P-C-60 back to DHI-P-C-60 may be achieved with visible light, or thermally. Thus, photoinduced charge separation originating from the porphyrin is reversibly directed down either of two different pathways by photoisomerization of the dihydroindolizine. The switch may be cycled many times.
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