Chiral Anthranyl Trifluoromethyl Alcohols: Structures, Oxidative Dearomatization and Chiroptical Properties

Chiral trifluoromethyl alcohol groups were introduced at the hindered ortho positions of 9,10-diphenylanthracenes to investigate their effects on the physical properties and reactivity towards oxidative dearomatization. In such compact structures, the position in different quadrants and the preferred orientation of the -CH(OH)CF₃ groups were determined by the relative and absolute configurations of each stereoisomer, respectively. As a consequence, the stereochemistry governs the organization of the H-bonded molecules in single crystals (homochiral dimers vs ribbon), whereas in chlorinated solvents, they all behave as discrete compounds. Concerning their reactivity, the stereospecific dearomative oxidation of these molecules leads to 9,10-bis-spiro-isobenzofuran-anthracenes, when using organic single-electron transfer oxidants. The chiroptical properties of the alcohols and the corresponding dearomatized products were compared and showed an important modulation of the intensity.

A Supramolecular Strategy for Enhancing Photochirogenic Performance through Host/Guest Modification: Dicationic γ-Cyclodextrin-Mediated Photocyclodimerization of 2,6-Anthracenedicarboxylate

Possessing an extra anionic handle for chiral supramolecular interactions, 2,6-anthracenedicarboxylate exhibited greater photochirogenic performance than 2-anthracenecarboxylate to afford the anti-cyclodimer in up to 94% yield and -72% enantiomeric excess upon photoirradiation with dicationic γ-cyclodextrins.

A phototunable anion receptor for C-HX interactions with benzoate anions

A supramolecular receptor consisting of two anthracene moieties with binding motifs for binding of benzoate anions is reported here. NMR studies indicate that the binding involves π-π interactions and CHX interactions. Upon exposure to >350 nm light, the receptor undergoes a [4 + 4] photoelectrocyclization restricting the access to the binding site for benzoate. The reverse reaction works in the presence of the dual stimuli of 254 nm light and the benzoate anions. The work thus demonstrates a light mediated dynamic control of the binding pocket of a supramolecular anion receptor.

Porous organic–inorganic hybrid xerogels for stearic acid shape-stabilized phase change materials

The high surface area, porosity and gel properties of MOG-100 (Cr) ensure the excellent thermal properties of SA@MOG-100 (Cr) composites.

Arene-Alkene Cycloaddition

Cycloadditions are among the most efficient chemical processes, combining atom economy, stereospecificity, and the ability to generate molecular complexity in a single step. Aromatic rings would in principle be ideal reaction partners, as they contain, at least from the topological point of view, both olefinic and diene subunits; however, the stability of the conjugated aromatic system would be broken by cycloaddition reactions, which are therefore rarely applied, because kinetics and thermodynamics hinder the process. From that aspect, photochemical activation opens interesting perspectives, as one can selectively provide excess energy to one of the reactants but not to the product, thus preventing thermal back reaction. Indeed, aromatic rings show a rich photochemistry, ranging from isomerizations, substitutions, and additions to cycloadditions. In this review, we will focus on cycloadditions, covering literature from early observations up to the present.

A Chiroptical Logic Circuit Based on Self-Assembled Soft Materials Containing Amphiphilic Spiropyran

A chiral logic circuit is proposed based on the multiple chiroptical responsiveness of a supramolecular gel material. The gel is fabricated by mixing a chiral gelator and a spiropyran derivative. Chiral responsiveness including the chiral switch and the logic gate is realized through the combined chirality transfer, photochromism, and acidichromism of the system.

Enantioselective [4+4] photodimerization of anthracene-2,6-dicarboxylic acid mediated by a C2-symmetric chiral template

A chiral template was shown to bind the title compound by hydrogen bonding resulting in enantioselectivities of up to 55% enantiomeric excess (ee) in the [4+4] anthracene photodimerization.

A highly selective and sensitive photoswitchable fluorescent probe for Hg2+ based on bisthienylethene-rhodamine 6G dyad and for live cells imaging

A new photochromic diarylethene derivative bearing rhodamine 6G dimmer as a fluorescent molecular probe is designed and synthesized successfully. All the compounds are characterized by nuclear magnetic resonance and mass spectrometry. The bisthienylethene-rhodamine 6G dyad exhibit excellent phtochromism with reversibly color and fluorescence changes alternating irradiation with ultraviolet and visible light. Upon addition of Hg(2+), its color changes from colorless to red and its fluorescence is remarkably enhanced. Whereas other ions including K(+), Na(+), Ca(2+), Mg(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Mn(2+), Pb(2+), Ni(2+), Fe(3+), Al(3+), Cr(3+) and so on induce basically no spectral changes, which constitute a highly selective and sensitive photoswitchable fluorescent probe toward Hg(2+). Furthermore, by means of laser confocal scanning microscopy experiments, it is demonstrated that this probe can be applied for live cell imaging and monitoring Hg(2+) in living lung cancer cells with satisfying results, which shows its value of potential application in environmental and biological systems.

Volume change during thermal [4 + 4] cycloaddition of [2.2] (9,10)anthracenophane

We show that the reaction path connecting the tethered bi(anthracene-9,10-dimethylene) and its photodimer proceeds stepwise via a diradicaloid transition state where one σ-bond is made before a second. The newly found transition state (TS) has a smaller molecular volume than either the reactant or the product giving an atomistic explanation to the recently found pressure catalyzed barrier lowering and rate enhancement. The density functional methods used include long-range contributions as required in a system where the dispersion interactions are significant. We discuss this transformation in the context of the diamond-to-graphite transition owing to the similarity of σ-bond breakage into a delocalized π-system. We also comment on the controversy surrounding the equilibrium geometries of photoisomerized cyclophanes, concluding that D2h symmetry in the photoisomer of the title molecule is a transition structure connecting a pair of degenerate ground state D2 geometries.