Binaphthyl–Bipyridyl Cyclic Dyads as a Chiroptical Switch

A series of chiral cyclic dyads, axially chiral binaphthyls linked to a 3,3′-bipyridyl, was synthesized. The dyad <b>2</b> bearing methoxy groups exhibited ON/OFF properties in circularly polarized luminescence (CPL), yielding a |<i>g</i>_lum| of 1.6 × 10^–3 or 0 without any change in fluorescence. This type of CPL switch is unprecedented. Regioisomer <b>4</b> exhibited a <i>dextro</i>/<i>levo</i> rotation switching ability in [α]_D. X-ray structures as well as experimental and theoretical analyses suggested that the switching properties depended on conformational changes

Binaphthyl–Bipyridyl Cyclic Dyads as a Chiroptical Switch

A series of chiral cyclic dyads, axially chiral binaphthyls linked to a 3,3′-bipyridyl, was synthesized. The dyad <b>2</b> bearing methoxy groups exhibited ON/OFF properties in circularly polarized luminescence (CPL), yielding a |<i>g</i>_lum| of 1.6 × 10^–3 or 0 without any change in fluorescence. This type of CPL switch is unprecedented. Regioisomer <b>4</b> exhibited a <i>dextro</i>/<i>levo</i> rotation switching ability in [α]_D. X-ray structures as well as experimental and theoretical analyses suggested that the switching properties depended on conformational changes

Binaphthyl–Bipyridyl Cyclic Dyads as a Chiroptical Switch

A series of chiral cyclic dyads, axially chiral binaphthyls linked to a 3,3′-bipyridyl, was synthesized. The dyad <b>2</b> bearing methoxy groups exhibited ON/OFF properties in circularly polarized luminescence (CPL), yielding a |<i>g</i>_lum| of 1.6 × 10^–3 or 0 without any change in fluorescence. This type of CPL switch is unprecedented. Regioisomer <b>4</b> exhibited a <i>dextro</i>/<i>levo</i> rotation switching ability in [α]_D. X-ray structures as well as experimental and theoretical analyses suggested that the switching properties depended on conformational changes

Binaphthyl–Bipyridyl Cyclic Dyads as a Chiroptical Switch

A series of chiral cyclic dyads, axially chiral binaphthyls linked to a 3,3′-bipyridyl, was synthesized. The dyad <b>2</b> bearing methoxy groups exhibited ON/OFF properties in circularly polarized luminescence (CPL), yielding a |<i>g</i>_lum| of 1.6 × 10^–3 or 0 without any change in fluorescence. This type of CPL switch is unprecedented. Regioisomer <b>4</b> exhibited a <i>dextro</i>/<i>levo</i> rotation switching ability in [α]_D. X-ray structures as well as experimental and theoretical analyses suggested that the switching properties depended on conformational changes

Binaphthyl–Bipyridyl Cyclic Dyads as a Chiroptical Switch

A series of chiral cyclic dyads, axially chiral binaphthyls linked to a 3,3′-bipyridyl, was synthesized. The dyad <b>2</b> bearing methoxy groups exhibited ON/OFF properties in circularly polarized luminescence (CPL), yielding a |<i>g</i>_lum| of 1.6 × 10^–3 or 0 without any change in fluorescence. This type of CPL switch is unprecedented. Regioisomer <b>4</b> exhibited a <i>dextro</i>/<i>levo</i> rotation switching ability in [α]_D. X-ray structures as well as experimental and theoretical analyses suggested that the switching properties depended on conformational changes

Binaphthyl–Bipyridyl Cyclic Dyads as a Chiroptical Switch

A series of chiral cyclic dyads, axially chiral binaphthyls linked to a 3,3′-bipyridyl, was synthesized. The dyad <b>2</b> bearing methoxy groups exhibited ON/OFF properties in circularly polarized luminescence (CPL), yielding a |<i>g</i>_lum| of 1.6 × 10^–3 or 0 without any change in fluorescence. This type of CPL switch is unprecedented. Regioisomer <b>4</b> exhibited a <i>dextro</i>/<i>levo</i> rotation switching ability in [α]_D. X-ray structures as well as experimental and theoretical analyses suggested that the switching properties depended on conformational changes

Fusion of Photochromic Reaction and Synthetic Reaction: Photoassisted Cyclization to Highly Strained Chiral Azobenzenophanes

A method for synthesizing highly strained cyclic structures by combining photochromic and synthetic reactions is described. Tightly linked azobenzene–binaphthyl dyads (<i>R</i>)-<b>4</b> and (<i>R</i>)-<b>6</b> could not be obtained by conventional cyclization, but continuous application of photoirradiation, which induced (<i>E</i>)→(<i>Z</i>) isomerization of the azobenzene moiety, allowed the cyclization reaction to proceed, affording the desired chiral azobenzenophanes

Photoinversion of <i>Cisoid</i>/<i>Transoid</i> Binaphthyls

Axially chiral binaphthyl-azobenzene cyclic dyads in which the two moieties are connected by two linkers of different lengths were synthesized. In the case of benzylated-binaphthyl analogue <b>2b</b>, photoirradiation resulted in a dramatic change of the CD spectrum and optical rotation. Experimental and theoretical analyses indicated that the dihedral angle of the two naphthalene rings is strongly coupled to the azobenzene photoisomerization; <i>cis</i>-azobenzene induces a <i>transoid</i>-binaphthyl structure, while <i>trans</i>-azobenzene induces a <i>cisoid</i>-binaphthyl structure

Fusion of Photochromic Reaction and Synthetic Reaction: Photoassisted Cyclization to Highly Strained Chiral Azobenzenophanes

A method for synthesizing highly strained cyclic structures by combining photochromic and synthetic reactions is described. Tightly linked azobenzene–binaphthyl dyads (<i>R</i>)-<b>4</b> and (<i>R</i>)-<b>6</b> could not be obtained by conventional cyclization, but continuous application of photoirradiation, which induced (<i>E</i>)→(<i>Z</i>) isomerization of the azobenzene moiety, allowed the cyclization reaction to proceed, affording the desired chiral azobenzenophanes

Chiral Macrocyclic Organocatalysts for Kinetic Resolution of Disubstituted Epoxides with Carbon Dioxide

Among chiral macrocycles <b>1</b> synthesized, <b>1m</b> with the 3,5-bis­(trifluoromethyl)­phenylethynyl group was the best organocatalyst for the enantioselective synthesis of cyclic carbonates from disubstituted or monosubstituted epoxides and CO₂. The X-ray crystal structure of <b>1m</b> revealed a well-defined chiral cavity with multiple hydrogen-bonding sites that is suitable for the enantioselective activation of epoxides. A catalytic cycle proposed was supported by DFT calculations