Syntheses of chiral bishomodiazacalix[4]arenes incorporating amino acid residues: Molecular recognition for racemic ammonium ions by the macrocycles possessing tyrosine residues

Chiral bishomodiazacalix[4]arenes containing amino acid residues were prepared. The ¹H and ¹³C nmr spectra indicated that the macrocycles preferably adopted a cone conformation, which suggested that the cyclophane moiety was in a chiral twisted form. Circular dichroism spectra supported the existence of the chirality of the cyclophane unit, and showed that intramolecular hydrogen bonding plays an important role in the transmission of the chirality from the amino acid residues to the cyclophane moiety. Macrocycles bearing a tyrosine residue have a π‐base cavity large enough to include the ammonium ion, and can serve as a shift reagent for the racemic ammonium ions upon complexation during a ¹H nmr analysis.     

A Kinetically Stabilized [1.1]Paracyclophane: Isolation and X-Ray Structural Analysis

Benzene rings severely bent and closely stacked face-to-face are revealed in the crystal structure of the [1.1]paracyclophane derivative 1 , which could be isolated thanks to the kinetic stabilization provided by the steric shielding of the bridgehead sites by the substituents.     

Suppressed Migration and Enhanced Cisplatin Chemosensitivity in Human Cancer Cell Lines by Tuning the Molecular Mobility of Supramolecular Biomaterials

Cancer cells recognize physical cues transmitted from the surrounding microenvironment, and accordingly alter the migration and chemosensitivity. Cell adhesive biomaterials with tunable physical properties can contribute to the understanding of cancer cell responses, and development of new cancer therapies. Previously, it was reported that polyrotaxane-based surfaces with molecular mobility effectively modulate cellular functions via the yes-associated protein (YAP)-related signaling pathway. In the present study, the impact of molecular mobility of polyrotaxane surfaces on the migration and chemosensitivity of lung (A549), pancreatic (BxPC-3), and breast cancer (MDA-MB-231) cell lines is investigated, and it is found that the cellular spreading of adherent A549 and BxPC-3 cells and nuclear YAP translocation are promoted on low-mobility surfaces, suggesting that cancer cells alter their subcellular YAP localization in response to molecular mobility. Furthermore, low-mobility surfaces suppress cellular migration more than high-mobility surfaces. Additionally, low-mobility surfaces promote the cisplatin chemosensitivity of each cancer cell line to a greater extent than high-mobility surfaces. These results suggest that the molecular mobility of polyrotaxane surfaces suppresses cellular migration and enhances chemosensitivity via the subcellular translocation of YAP in cancer cells. Biointerfaces based on polyrotaxanes can thus be a new platform for elucidating cancer cell migration and chemoresistance mechanisms.     

Thermodynamics of polymeric fluids – effect of volume on the configurational entropy of chain molecules

Various conformation‐dependent properties of chain molecules have been successfully treated within the rotational isomeric state approximation. The conformation entropy is one of such properties which can be readily defined by the partition function, the sum of all possible configurations of the chain. Flexible polymers often exhibit crystallization and in some cases liquid‐crystallization as well. In these first‐order transitions, changes in the spatial arrangement of polymer chains are considered to be a major factor involved. In order to explicitly determine the conformational contribution to the melting entropy, the latent entropy observed under the isobaric condition must be corrected for the volume change. The entropy separation involves a hypothetical assumption that the volume of the isotropic fluid may be compressed to that of the solid state without affecting the configurational part of the entropy of molecules. Finally thermodynamic significance of the conformation entropy in these transitions is emphasized on the basis of the critical studies of the entropy‐volume relation of chain molecules in the liquid state.     

Polarization imaging by use of optical scanning holography

Optical Review - Polarization information is useful for various applications such as remote sensing and biomedical imaging. In general, polarization information is obtained using a polarization...