Yoshitane Imai

Control of circularly polarized luminescence by using open- and closed-type binaphthyl derivatives with the same axial chirality.

The solution-dispersed-state and polymer-dispersed-state circular dichroism (CD) and circularly polarized luminescence (CPL) properties of chiral binaphthyl fluorophores could be controlled by the choice of open- or closed-type substituents on the binaphthyl units and by the axial chirality of the binaphthyls.

Control of the Solid‐State Chiral Optical Properties of a Supramolecular Organic Fluorophore Containing 4‐(2‐Arylethynyl)‐Benzoic Acid

The solid-state chiral optical properties of a 4-(2-arylethynyl)-benzoic acid/amine supramolecular organic fluorophore can be controlled by changing the arylethynyl group of the achiral 4-(2-arylethynyl)-benzoic acid component molecule rather than the chirality of the amine component molecule.

A Solid-State Fluorescent Host System with a 21-Helical Column Consisting of Chiral (1R,2S)-2-Amino-1,2-diphenylethanol and Fluorescent 1-Pyrenecarboxylic Acid

A solid-state fluorescent host system was created by self-assembly of a 2(1)-helical columnar organic fluorophore composed of (1R,2S)-2-amino-1,2-diphenylethanol and fluorescent 1-pyrenecarboxylic acid. This host system has a characteristic 2(1)-helical columnar hydrogen- and ionic-bonded network. Channel-like cavities are formed by self-assembly of this column, and various guest molecules can be included by tuning the packing of this column. Moreover, the solid-state fluorescence of this host system can change according to the included guest molecules. This occurs because of the change in the relative arrangement of the pyrene rings as they adjust to the tuning of the packing of the shared 2(1)-helical column, according to the size of the included guest molecules. Therefore, this host system can recognize slight differences in molecular size and shape.

Generation of a co-crystal phase with novel coloristic properties via solid state grinding procedures

Co-grinding of crystals of racemic-bis-beta-naphthol (rac-BN) and benzoquinone (BQ) produces a novel crystal adduct through crystal sheering and molecular diffusion processes in the solid state, which is structurally distinct from adducts obtained from solution or melt.

Dependence of circularly polarized luminescence due to the neighboring effects of binaphthyl units with the same axial chirality

The solution-dissolved-state circular dichroism (CD) and the circularly polarized luminescence (CPL) of chiral binaphthyl fluorophores was controlled by both the axial chirality of the binaphthyl units as well as by the effect of neighboring binaphthyl units.

Nonclassical Tunability of Solid‐State CD and CPL Properties of a Chiral 2‐Naphthalenecarboxylic Acid/Amine Supramolecular Organic Fluorophore

The solid-state chiral optical properties (circular dichroism and circularly polarized luminescence) of a 2-naphthalenecarboxylic acid/amine supramolecular organic fluorophore can be controlled by changing the aryl unit of the chiral 1-arylethylamine component of the molecule rather than altering the chirality of the 1-arylethylamine itself.

Control of circularly polarized luminescence (CPL) properties by supramolecular complexation

The sign of circularly polarized luminescence (CPL) of a chiral 21-helical columnar organic fluorophore was successfully controlled in the solid-state by changing an achiral fluorescence component molecule, and not by using a chiral component molecule with opposite chirality.

Multiple molecular response columnar host system composed of rac-2-amino-1,2-diphenylethanol and 1-fluorenecarboxylic acid

By using racemic (rac)-2-amino-1,2-diphenylethanol and achiral fluorescent 1-fluorenecarboxylic acid, a two-component columnar host system with multiple molecular response (guest-dependent spontaneous resolution and fluorescence) properties in the solid state was created.

Conformational and color polymorphism of achiral 2-methyl-3-(2-naphthalenylthio)-1,4-naphthalenedione

An achiral compound, 2-methyl-3-(2-naphthalenylthio)-1,4-naphthalenedione, shows conformational and color polymorphism, and each polymorph shows different optical properties and can be controlled by changing crystallization conditions.

Varied charge-transfer complex crystals formed between diols and benzoquinone in the solid and solution states

Co-grinding of crystals of diols (electron donor) and benzoquinone (BQ, electron acceptor), and in some cases with crystals of a third aromatic compound, produces charge transfer (CT) complex crystals in the solid state without going through an obvious amorphous state, followed by a change in colour and in powder X-ray diffraction patterns. A milling power above a threshold is required for the new CT complex crystal formation, however, in some cases simple mixing of pulverized crystals is good enough to initiate the transformation. On exposing the CT complex crystals to air, without any mechanochemical force, they revert to the starting diol crystals by losing sublimable BQ molecules, rearranging hydrogen bonds and establishing a three-dimensional periodicity. Remarkably, solid-state and conventional solution crystallization give different results, i.e., formation or non-formation of CT complex crystals, or formation of different crystals with different colours. The phenomenon is surprisingly frequent and all three two-component CT systems and six out of the nine three-component systems investigated, exhibit different crystallization behaviour. A quartet structure where two BQ molecules are sandwiched by two naphthols was formed in the crystal obtained from solid-state crystallization. A new triplet CT complex structure in which a BQ is sandwiched by a naphthol and a biphenyl is also reported.