Piezochromic fluorescence in liquid crystalline conjugated polymers

Liquid crystalline diphenylacetylene polymer derivatives showed piezochromic fluorescence via order-to-disorder phase transition.     

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 charge-transfer host system composed of a chiral 1,1′-bi-2-naphthol cluster and benzylviologen

Chiral charge-transfer (CT) complexes composed of a chiral 1,1′-bi-2-naphthol cluster as the electron donor and 1,1′-dibenzyl-4,4′-bipyridinium dichloride as the electron acceptor serve as a host system for molecular recognition. CT complexes that include guest alcohols show different diffuse reflectance spectra (DRS) depending on the included guest.     

Hydrogen bonding of urea-salicylic acid,U·SA

Urea (U) and salicylic acid (SA) crystallize from aqueous solution as a 11 adduct whose structure shows them to be linked via several weak and one strong hydrogen bonds. The ir spectra of the adduct and its deuterated counterpart have been analyzed and the stretching modes of the various hydrogen bonds identified. The¹H and¹³C nmr. spectra are also interpreted to show that discrete adducts of U·SA persist in solution. On heating, U·SA decarboxylates at a much lower temperature than SA itself.     

Raman spectra in hollandite type compounds K1.6Mg0.8Ti16 and K1.6Al1.6Ti6.4O16

Raman spectra of single crystals of one-dimensional superionic conductors K_1.6Mg_0.8Ti_7.2O₁₆ and K_1.6Al_1.6Ti_6.4O₁₆ have been measured. Both the spectra show very similar features one another. Raman peaks in K_1.6Mg_0.8Ti_7.2O₁₆ appear at low frequencies compared to corresponding Raman peaks in K_1.6Al_1.6Ti_6.4O₁₆. A qualitative interpretation of these spectra is examined in terms of a comparison with the Raman spectra of rutile and the factor group analysis.     

Aggregation behaviors of gemini nucleotide at the air-water interface and in solutions induced by adenine-uracil interaction

Cationic gemini surfactants having nucleotides as counterions (called nucleo-gemini hereafter) were synthesized and their aggregation behavior at air-water surfaces as well as in bulk solutions were studied. Fluid solutions of these nucleo-gemini surfactants show transitions to hydrogels upon addition of complementary nucleoside bases or other nucleo-gemini surfactants having complementary bases as counterions. The FTIR-ATR measurements show that the carboxylate groups of uridine form hydrogen bonds with the amine groups of adenosine. The aggregation behavior was also confirmed at the air-water interface by Brewster angle microscopy as well as surface pressure measurements; the monolayer of a gemini nucleotide was observed to undergo a transition to multilayers when nucleosides with complementary bases were added into the subphase. Isotherm curves of surface pressure monitored in parallel show a decrease in molecular area upon addition of such nucleosides.