ALL-OPTICAL CONTROL OF MOLECULAR FUNCTIONS - ENERGY TRANSFER SWITCHING AND INFORMATION PROCESSING
Doktorsavhandling, 2016

In this work, the photoswitching of molecular systems endowed with photochromic functionality have been investigated for the reversible photonic gating of excitation energy transfer (FRET) reactions as well as in application for all-photonic molecular logic. The presented systems involves the integration of photochromic entities within both covalent and non-covalent designs and serves to implicate photonic switching of molecular level phenomena. In particular, all systems include the photochromic modulation of fluorescence emission in response to photonic stimuli. In the first part of this thesis, paper I and II, two different molecular logic systems were designed as to investigate the possibility of using photochromic molecular functions with fluorescent read-out as new possible logic platforms in all-photonic information processing and data storage. In paper I, we present the utilization of a fluorescent photochromic fulgimide derivative in combination with non-linear (SHG/THG) crystals and Nd:YAG lasers for the successful implication of an all-photonic molecular D-flip flop. In paper II, we show the covalent integration of photochromic fulgimide and dithienylethene derivatives into two different photochromic triads, resulting in a “neuron”-like off-on-off fluorescence emission behavior in response to illumination with UV-light, which allowed the implication of an all-photonic molecular parity generator/checker. In the second part, papers III and VI, the possibilty for using photochromic compounds in the construction of photoresponsive supramolecular assemblies was explored. In paper III, we show the reversible photoswitching of excitation energy transfer between a donor-acceptor (FRET) pair appended to a DNA-template by photochromic modulation of the DNA-binding properties of an amidine-substituted spiropyran derivative. In paper IV, we show dichromatic emission color-tuning and generation of virtually perfect white light fluorescence by regulation of FRET communication between a donor fluorophore and a fluorescent photoswitch encapsulated in polymer micelles.

white-light generation

molecular logic

spiropyran

photochromism

DNA-binding

diarylethene

energy transfer

all-photonic

fulgimide

dithienylethene

photoswitch

fluorescence modulation

KB-salen, Kemigården 4, Campus Johanneberg, Chalmers
Opponent: Professor Amilra De Silva, Chemistry and Chemical Engineering, Queen's University, Belfast, Ireland

Författare

Magnus Bälter

Kemi och kemiteknik, Kemi och biokemi, Fysikalisk kemi

Fotokromism är egenskapen hos en molekyl att förändra färg då den exponeras för ljus. Denna förändring kommer sig av att när en fotokrom molekyl absorberar ljus så genomgår den en omvandling från en molekylär struktur till en annan, och således ändras också molekylens absorption och färg. I och med att de två olika formerna, också kallade isomerer, har olika struktur så betyder det också att de har skilda kemiska egenskaper. Tack vare dessa skilda kemiska egenskaper så fungerar de fotokroma molekyler som kemiska switchar. Genom att bygga in fotokroma funktioner i molekylära system kan vi därigenom erhålla förmågan att styra fenomen på molekylär nivå genom att exponera dem för olika våglängder av ljus.

Ämneskategorier

Fysikalisk kemi

ISBN

978-91-7597-398-2

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie

KB-salen, Kemigården 4, Campus Johanneberg, Chalmers

Opponent: Professor Amilra De Silva, Chemistry and Chemical Engineering, Queen's University, Belfast, Ireland