Light-Responsive Oligothiophenes Incorporating Photochromic Torsional Switches (PTS)

We present a quaterthiophene and sexithiophene that can reversibly change their effective π-conjugation length via photoexcitation. The reported compounds make use of light-responsive molecular actuators consisting of an azobenzene attached to a bithiophene unit by both direct and linker-assisted bonding. Upon exposure to 350 nm light the azobenzene undergoes trans -to- cis isomerization mechanically inducing the oligothiophene to assume a planar conformations (extended π-conjugation). Exposure to 254 nm wavelenght promotes azobenzene cis -to- trans isomerization, forcing the thiophenic backbones to twist out of planarity (confined π-conjugation). Twisted conformations are also reached by cis -to- trans thermal relaxation with rate that increases proportionally with the conjugation length of the oligothiophene moiety. The molecular conformations of quaterthiophene and sexithiophene were characterized using steady-state UV-vis, X-ray crystallography and quantum-chemical modelling. Finally, we tested the proposed light-responsive oligothiophenes into field-effect transistors to probe the photo-induced tuning of their electronic properties

Expression of proteins of interest in food

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Compound for uses in optical and electrooptical devices

which can also be embedded into a conjugated oligomeric of polymeric backbone, is proposed for optical and electro optical applications

Elucidating Charge Generation in Green-Solvent Processed Organic Solar Cells

Organic solar cells have the potential to become the cheapest form of electricity. Rapid increase in the power conversion efficiency of organic solar cells (OSCs) has been achieved with the development of non-fullerene small-molecule acceptors. Next generation photovoltaics based upon environmentally benign “green solvent” processing of organic semiconductors promise a step-change in the adaptability and versatility of solar technologies and promote sustainable development. However, high-performing OSCs are still processed by halogenated (non-environmentally friendly) solvents, so hindering their large-scale manufacture. In this perspective, we discuss the recent progress in developing highly efficient OSCs processed from eco-compatible solvents, and highlight research challenges that should be addressed for the future development of high power conversion efficiencies devices

Double-channel photosystems with antiparallel redox gradients: templated stack exchange with porphyrins and phthalocyanines

We report the synthesis of multicomponent surface architectures composed of phthalocyanines (Pc), porphyrins (TPP) and naphthalenediimides (NDI). Naphthalenediimide stacks are grown first by self-organizing surface initiated disulfide-exchange polymerization (SOSIP). An oriented redox gradient driving electrons toward the surface is applied by growing electron-richer NDI stacks on top of poorer ones. Lateral stacks of porphyrins and phthalocyanines are then added by templated stack exchange (TSE). A three-component gradient is constructed to drive the holes away from the solid surface. Antiparallel gradients are found to minimize charge recombination during photocurrent generation. Templates used for stack exchange also serve as hole barriers, whereas their size has surprisingly little importance. These results demonstrate the compatibility of SOSIP-TSE technology with porphyrins and phthalocyanines, confirm the importance of oriented antiparallel gradients to minimize charge recombination, and show that electronics rather than the size matter to template stack exchange

Toward Oriented Surface Architectures with Three Coaxial Charge-Transporting Pathways

We report a synthetic method to build oriented architectures with three coaxial π-stacks directly on solid surfaces. The approach operates with orthogonal dynamic bonds, disulfides and hydrazones, self-organizing surface-initiated polymerization (SOSIP), and templated stack-exchange (TSE). Compatibility with naphthalenediimides, perylenediimides, squaraines, fullerenes, oligothiophenes, and triphenylamine is confirmed. Compared to photosystems composed of two coaxial channels, the installation of a third channel increases photocurrent generation up to 10 times. Limitations concern giant stack exchangers that fail to enter SOSIP architectures (e.g., phthalocyanines surrounded by three fullerenes), and planar triads that can give folded or interdigitated charge-transfer architectures rather than three coaxial channels. The reported triple-channel surface architectures are as sophisticated as it gets today, the directionality of their construction promises general access to multichannel architectures with multicomponent gradients in each individual channel. The reported approach will allow us to systematically unravel the ultrafast photophysics of molecular dyads and triads in surface architectures, and might become useful to develop conceptually innovative optoelectronic devices

Poly(disulfide)s

Don't forget poly(disulfide)s. There is a rich literature pointing out the advantages of the dynamic nature of single disulfide bridges to explore self-sorting, biomolecular engineering, biomembrane analysis, and so on. Disulfide bonds between polymer chains are essential for protein folding, materials properties and the stabilization of various supramolecular architectures. However, poly(disulfide)s with disulfide bonds in the main chain are rarely used today to create interesting structures or functions. To attract attention and outline scope and limitations of poly(disulfide)s to build modern supramolecular systems, the rather eclectic recent literature on the topic is summarized. The review is moving from fascinating basic studies including photoinduced metathesis, polycatenanes and polyrotaxanes to applications in biosupramolecular systems such as micelles, membranes, tubes, gels, carriers, pores, sensors, catalysts and photosystems

Analyzing Fluxional Molecules Using DORI

The Density Overlap Region Indicator (DORI) is a density-based scalar field that reveals covalent bonding patterns and non-covalent interactions in the same value range. This work goes beyond the traditional static quantum chemistry use of scalar fields and illustrates the suitability of DORI for analyzing geometrical and electronic signatures in highly fluxional molecular systems. Examples include a dithiocyclophane, which possesses multiple local minima with differing extents of π-stacking interactions and a temperature dependent rotation of a molecular rotor, where the descriptor is employed to capture fingerprints of CH- and - interactions. Finally, DORI serves to examine the fluctuating π-conjugation pathway of a photochromic torsional switch (PTS). Attention is also placed on post-processing the large amount of generated data and juxtaposing DORI with a data-driven low-dimensional representation of the structural landscape

Synthesis and characterization of a new triazine-based NUV-blue excitable material for phosphor-converted LED technologies

A novel blue excitable green fluorescent triazine-based material with high thermal stability (up to 350 °C) has been synthesized. Solid-state structural characterizations showed bright solid-state photoluminescence centered at 490 nm with an internal quantum yield (iQY) up to 40%. The coordination capabilities offered by the presence of a multi nitrogen and oxygen heteroatom framework allows to use TABNO (4,4′,4′′,4′′′-((6,6′-oxybis(1,3,5-triazine-6,4,2-triyl))tetrakis(azanediyl))tetrabenzonitrile) as Tb3+ and Eu3+ photosensitizer, thus delivering a purely organic host matrix for Ln ions with tunable light emissions. Blending this new material with K2SiF6:Mn4+ allowed access to a new class of REE free NUV-blue excitable warm light-emitting phosphors

Analyzing Fluxional Molecules Using DORI

The Density Overlap Region Indicator (DORI) is a density-based scalar field that reveals covalent bonding patterns and noncovalent interactions in the same value range. This work goes beyond the traditional static quantum chemistry use of scalar fields and illustrates the suitability of DORI for analyzing geometrical and electronic signatures in highly fluxional molecular systems. Examples include a dithiocyclophane, which possesses multiple local minima with differing extents of π-stacking interactions and a temperature dependent rotation of a molecular rotor, where the descriptor is employed to capture fingerprints of CH-π and π–π interactions. Finally, DORI serves to examine the fluctuating π-conjugation pathway of a photochromic torsional switch (PTS). Attention is also placed on postprocessing the large amount of generated data and juxtaposing DORI with a data-driven low-dimensional representation of the structural landscape