Amplified Chirality Transfer to Aromatic Molecules through Non-specific Inclusion by Amorphous, Hyperbranched Poly(fluorenevinylene) Derivatives.

Optically active, hyperbranched, poly(fluorene-2,4,7-triylethene-1,2-diyl) [poly(fluorenevinylene)] derivatives bearing a neomenthyl group and a pentyl group at the 9-position of the fluorene backbone at various ratios acted as a chirality donor (host polymers) efficiently included naphthalene, anthracene, pyrene, 9-phenylanthracene, and 9,10-diphenyanthracene as a chirality acceptor (guest molecules) in their interior space in film as well as in solution, with the guest molecules exhibiting intense circular dichroism through chirality transfer with chirality amplification. The efficiency of the chirality transfer was much higher with higher-molar-mass polymers than lower-molar-mass ones as well as with hyperbranched polymers compared to the analogous linear ones. The hyperbranched polymers include the small molecules in their complex structure without any specific interactions at various stoichiometries.

Non-uniform Self-folding of Helical Poly(fluorenevinylene) Derivatives in the Solid State Leading to Amplified Circular Dichroism and Circularly Polarized Light Emission.

An unprecedented non-uniform self-folding of artificial polymer chains composed of turn moieties and stretched segments is presented through the design of a set of optically active poly(fluorene-2,7-diylethene-1,2-diyl) (poly(fluorenevinylene)) derivatives bearing a neomenthyl group and a pentyl group attached at the 9-position of fluorene backbone at various ratios. The folded structure is formed and stabilized through inter-chain interactions in the solid state, leading to remarkably enhanced chiroptical properties (chirality amplification) in terms of circular dichroism (CD) and circularly polarized light (CPL) emission. This phenomenon is rationalized by experimental and theoretical CD and CPL spectral analyses.

Aggregation-induced chirality amplification of optically active fluorescent polyurethane and a cyclic dimer in the ground and excited states.

Optically active linear polyurethane and a cyclic dimer were synthesized from 2,7-diisocyanatofluorene and 2,2'-dihydroxy-1,1'-binaphthyl. The circular dichroism (CD) spectral intensity of the polymer was amplified at a higher concentration through aggregate formation, while circularly polarized light (CPL) emission was not enhanced. The cyclic dimer's CPL emission was largely amplified ( 1.

Optically active covalent organic frameworks and hyperbranched polymers with chirality induced by circularly polarized light.

Axial chirality was induced by circularly polarized light to covalent organic frameworks as well as hyperbranched polymers composed of bezene-1,3,5-triyl core units and oligo(benzene-1,4-diyl) as linker units where variation in induction efficiency was rationally interpreted in terms of internal rotation dynamics studied through CPMAS 13C NMR experiments including CODEX measurements.

Blue circularly polarized luminescent amorphous molecules with single-handed propeller chirality induced by circularly polarized light irradiation.

Preferred-handed propeller conformation was induced by circularly polarized light irradiation to three amorphous molecules with trigonal symmetry, and the molecules with induced chirality efficiently exhibited blue circularly polarized luminescence. In both chirality induction and luminescence, chirality appeared to be amplified due to intermolecular interactions through π-stacking.

Metal-dependent regioselective homocoupling of stannyl- and alkyl-substituted alkynes on group 4 elements. Formation of unsymmetrical titanacyclopentadienes and symmetrical zircona-cyclopentadienes.

Homocoupling of stannyl- and alkyl-substituted alkynes with CpTiBu gave unsymmetrical titanacyclopentadienes (αβ isomers) with >95% regioselectivities, whereas the coupling with CpZrBu provided symmetrical zirconacyclopentadienes (αα isomers) with >93% selectivities. This is the first example of metal-dependent regioselective homocoupling of unsymmetrical alkynes on group 4 elements.

Formation of a spiro compound via coupling of a cyclopentadienyl ligand with a diene moiety of titanacyclopentadiene.

The treatment of titanacyclopentadienes with bismuth(iii) chloride gave spiro compounds in moderate yields. Two carbon atoms of the diene moiety of the titanacyclopentadiene were connected to one carbon atom of the Cp ligand. This is in sharp contrast to the formation of dihydroindene derivatives, where two carbon-carbon bonds were formed between the diene moiety and the adjacent two carbon atoms of the Cp ligand.