Mapping the Extended Ground State Reactivity Landscape of a Photoswitchable Molecule at a Single Molecular Level.

Photoswitchable molecules with structural flexibility can exhibit a complex ground state potential energy landscape due to the accessibility of multiple metastable states at merely low energy barriers. However, conventional bulk analytical techniques are limited in their ability to probe these metastable ground states and their relative energies. This is partially due to the difficulty of inducing changes in small molecules in their ground state, as they do not respond to external stimuli, such as mechanical force, unless they are incorporated into larger polymer networks.

Electron-Transfer-Induced Structural Modification in a Thermochromic Hofmann Clathrate Derivative.

This study explores a Hofmann-type clathrate, {Fe(2,4-(OCH)-bpy)(HO)[μ-Pt(CN)][μ-Pt(CN)]·4HO}, which exhibits a thermally activated electron transfer (ET) without spin crossover. Synthesized as microcrystalline powders and single crystals, this compound reveals significant structural changes upon variation of the temperature, including alterations in the iron coordination sphere due to the large movement of the bipyridinium ligand. These changes correlate with a thermochromic hysteretic transition from yellow to orange.

Dual Luminescent Mn(II)-Doped Cu-In-Zn-S Quantum Dots as Temperature Sensors in Water.

CuInS quantum dots have emerged in the last years as non-toxic alternative to traditional Pb and Cd based quantum dots, especially for biological applications. In this work, the hydrothermal synthesis of alloyed Cu-In-Zn-S quantum dots (CIZS) doped with manganese(II) is explored, with different metal ratios (Mn-CIZSy). The doped quantum dots show the sensitized emission of Mn (approximately ms lifetime), together with the emission of the CIZS structure (approximately µs lifetime).

Stable Meisenheimer Complexes as Powerful Photoreductants Readily Obtained from Aza-Hetero Aromatic Compounds.

Excited states of radical anions derived from the photoreduction of stable organic molecules are suggested to serve as potent reductants. However, excited states of these species are too short-lived to allow bimolecular quenching processes. Recently, the singlet excited state of Meisenheimer complexes, which possess a long-lived excited state, was identified as the competent species for the reduction of challenging organic substrates (-2.

Copper indium sulfide quantum dots enabling quantitative visible light photoisomerisation of ()-azobenzene chromophores.

Azobenzene derivatives have long been studied for their photochromic behaviour. One of the greatest challenges in this field is the quantitative () to () photoconversion triggered by visible light irradiation. In this work, the synthesis and characterization of CuInS quantum dots (CIS-QDs) appended with azobenzene units are reported: quantitative () → () isomerisation is obtained by visible light (, = 533 nm).

Optical modulation of cell nucleus penetration and singlet oxygen release of a switchable platinum complex.

The activation of anticancer molecules with visible light constitutes an elegant strategy to target tumors and to improve the selectivity of treatments. In this context, we report here a visible-light activatable bis-platinum complex () incorporating an organic photo-switchable ligand based on the dimethyldihydropyrene moiety. Illumination of this metal complex with red light (660 nm) under air readily produces the corresponding endoperoxide form ().

All Visible Light Photoswitch Based on the Dimethyldihydropyrene Unit Operating in Aqueous Solutions with High Quantum Yields.

Molecular systems and devices whose properties can be modulated using light as an external stimulus are the subject of numerous research studies in the fields of materials and life sciences. In this context, the use of photochromic compounds that reversibly switch upon light irradiation is particularly attractive. However, for many envisioned applications, and in particular for biological purposes, illumination with harmful UV light must be avoided and these photoactivable systems must operate in aqueous media.

Synthesis of a Negative Photochrome with High Switching Quantum Yields and Capable of Singlet-Oxygen Production and Storage.

A dimethyldihydropyrene (DHP) photochromic unit has been functionalized by donor (triphenylamine group) and acceptor (methylpyridinium) substituents. This compound was characterized by NMR, absorption and emission spectroscopies as well as cyclic voltammetry, and its properties were rationalized by theoretical calculations. The incorporation of both electron-donor and -withdrawing groups at the photochromic center allows i) an efficient photo-isomerization of the system when illuminated at low energy (quantum yield: Φ =13.

Metal free oxidation of vinamidine derivatives: a simple synthesis of α-keto-β-diimine ligands.

Oxidation of vinamidinium salts with -chloroperbenzoic acid is the key synthetic step towards new persistent 1,3-di(amino)oxyallyl radical cations. When applied to parent vinamidines, this protocol allows for a simple straightforward synthesis of α-keto-β-diimine ligands, for which no convenient synthesis was previously available.