Study of Cholesteric Textures in Phase Change Devices by Laser Light Diffraction

Photographic-recording and photomultiplier-recording laser light diffractometers have been constructed and used to study the cholesteric textures in phase change devices as a function of applied voltage and device parameters. The focal conic texture formed with increasing voltage gives diffraction peaks corresponding to 2π rotations of the director, whereas the texture formed by slow nucleation with decreasing voltage also gives “superlattice” lines corresponding to a 4π repeat, due to the different local structures of the textures combined possibly with tilting of the director. The repeat distances obtained by indexing the diffraction patterns agree well with microscopical and infra-red reflectance observations. Laser light diffraction appears to be a powerful technique for quantitative study of the non-uniform unwinding and re-forming of cholesteric twist in an electric field.     

One‐Step Multicomponent Self‐Assembly of a First‐Generation Sierpiński Triangle: From Fractal Design to Chemical Reality

A novel terpyridine‐based architecture that mimics a first‐generation Sierpiński triangle has been synthesized by multicomponent assembly and features tpy? Cd^II? tpy connectivity (tpy=terpyridine). The key terpyridine ligands were synthesized by the Suzuki cross‐coupling reaction. Mixing two different terpyridine‐based ligands and Cd^II in a precise stoichiometric ratio (1:1:3) produced the desired fractal architecture in near‐quantitative yield. Characterization was accomplished by NMR spectroscopy, mass spectrometry, and transmission electron microscopy.     

Two helium atoms inside fullerenes: probing the internal magnetic field in C60(6-) and C70(6-)

A 3He NMR resonance of C606- containing He is assigned to He2@C606-, thus showing that C60 can also accommodate two helium atoms. The ratio of the di-helium compound relative to the mono- is 1:200, 10 times lower than the equivalent counterpart of C70. The 3He NMR chemical shift of He2@C606- is 0.093 ppm downfield from the already known resonance of He@C606-. In the reduced endohedral mono- and di-helium C70, the 3He NMR chemical shift of He2@C706- is 0.154 ppm upfield from the peak of He@C706-.     

Ab initio calculations of the excited states of the permanganate and chromate ions

The excited states of the permanganate and chromate ions are described by better-than-minimal basis set SC FMO CI calculations. The results are compared with the experimental absorption spectra.