Storage and Processing of Information Using Molecules: The All-Photonic Approach with Simple and Multi-Photochromic Switches

Acid-base-induced fac → mer isomerization of luminescent iridium(iii) complexes

From fac to mer and back: a clean, fast and simple procedure for the transformation of fac-Ir(C^N)3 complexes into the thermodynamically less stable mer isomers is described. The process enables the interconversion of luminophores with distinct photophysical properties.

Visible Light Stimulated Bistable Photo-Switching in Defect Engineered Metal-Organic Frameworks

The incorporation of photoactive donor-acceptor Stenhouse adduct (DASA) moieties into Metal-Organic Frameworks (MOFs) provides a new route to the development of visible light switching materials. Herein, a DUT-5 mixed-linker defect series was exploited to produce a derivative group of DASA-modified materials via postsynthetic modification (PSM). The photoactive MOFs exhibited conversion stimulated by visible wavelengths and were stable following multiple cycles. Thermodynamic and metastable states persisted over an extended time period.

Photochromic dyes

This article describes the defining characteristics of photochromic dyes and highlights the subset of properties that are of greatest commercial importance. It outlines the history of the industrial exploitation of photochromic colorants before moving on to discuss current and potential applications. In doing so, a brief tour of key types of photochromic dye is provided.

Electrochemical Switching of First-Generation Donor-Acceptor Stenhouse Adducts (DASAs): An Alternative Stimulus for Triene Cyclisation

Donor-acceptor Stenhouse adducts (DASAs) are a photo-switch class that undergoes triene cyclisation in response to visible light. Herein, electrochemical oxidation is demonstrated as an effective alternative stimulus for the triene cyclisation commonly associated with photo-switching.

Photo-controlled bipolar absorption switches based on 5-dimethylamino substituted indoline spiropyrans with semipermanent merocyanines

A new element for molecular logic and all-optical information processing is proposed on the basis of P- and T-type photochromic systems existing as equilibrium of isomeric forms.

Cyclization Dynamics and Competitive Processes of Photochromic Perfluorocyclopentene Dithienylethylene in Solution

Time-resolved absorption spectroscopy measurements were performed to study the dynamics of photochromic 1,2-Bis(2,4-dimethylthiophene-3-yl)perfluoro-cyclopentene (DMTPF) in chloroform, including antiparallel conformer ring-closure reaction and parallel conformer photophysics. All characteristic times are given, discussed and compared to a previous publication concerning the close molecule substituted with phenyl rings. (Hamdi et al., PCCP, 2016). Apart from the expected photocyclization process, condensed ring by-product formation is observed and hypotheses concerning the origin of this by-product are presented.

Visible to near-IR molecular switches based on photochromic indoline spiropyrans with a conjugated cationic fragment

Photochromic molecules which can absorb and emit light within the "biological window" (650-1450 nm) are of great interest for using in various important biomedical applications such as bio-imaging, photopharmacology, targeted drug delivery, etc. Here we present three new indoline spiropyrans containing conjugated cationic fragments and halogen substituents in the 2H-chromene moiety which were synthesized by a simple one-pot method. The molecular structure of the obtained compounds was confirmed by FT-IR, ¹H and ¹³C NMR spectroscopy (including 2D methods), HRMS, elemental and single crystal X-ray analysis. Photochemical studies revealed the photochromic activity of spiropyrans at room temperature which caused photoswitchable fluorescence in the near-IR region after UV-irradiation. While the spirocyclic forms of compounds demonstrated absorption bands in the UV-Vis spectra with maxima in the visible region at about 445 nm and were not fluorescent, the photogenerated merocyanine isomers absorbed in the near-IR range at 708-738 nm and emitted at 768-791 nm. It was found that compound 1a with fluorine substituent possesses the most red-shifted absorption and emission bands of merocyanine form among all the known photochromic spiropyrans with maxima at 738 and 791 nm correspondingly. TD DFT calculations have shown that the longest wavelength absorption maxima of the merocyanine forms correspond to S₀-S₁ transitions of the isomers with at least one trans-trans-trans-configured vinylindolium fragment which brings them closer to cyanine-like structure and causes an appearance of the absorption and emission bands in the near-IR region.

Supramolecular Chemistry and Self-Organization: A Veritable Playground for Catalysis

The directed assembly of molecular building blocks into discrete supermolecules or extended supramolecular networks through noncovalent intermolecular interactions is an ongoing challenge in chemistry. This challenge may be overcome by establishing a hierarchy of intermolecular interactions that, in turn, may facilitate the edification of supramolecular assemblies. As noncovalent interactions can be used to accelerate the reaction rates and/or to increase their selectivity, the development of efficient and practical catalytic systems, using supramolecular chemistry, has been achieved during the last few decades. However, between discrete and extended supramolecular assemblies, the newly developed “colloidal tectonics” concept allows us to link the molecular and macroscopic scales through the structured engineering of colloidal structures that can be applied to the design of predictable, versatile, and switchable catalytic systems. The main cutting-edge strategies involving supramolecular chemistry and self-organization in catalysis will be discussed and compared in this review.

Multifunctional Photonic Molecular Logic Gate Based On A Biphotochromic Dyad With Reduced Energy Transfer

Using molecular logic gates (MLGs) for information processing attracts attention due to perspectives of creating molecular computers. Biphotochromic dyads are suitable models of photonic MLGs. However, they suffer from one weakness: the activity of one of the photochromes is often quenched because of Förster resonance energy transfer (FRET). Herein, we designed a dyad with reduced FRET, in which both photochromes keep their photoactivity thanks to spectral and spatial separation, allowing MLG switching between different states. This novel dyad reproduces the functionality of the full set of 16 two-input gates, as well a reversible gate-dual inverter, all gates are photonic.