Tuning polarity by solid solutions of molecular crystals

Tuning solid-state blue and red luminescence by the formation of solvate crystals.

Tuning and controlling the solid-state luminescence of molecular solids play a key role in developing multi-color displays and tunable dye laser. In this work, we report the tunable blue and red luminescence by the formation of solvate crystals of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) and 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM). Upon introduction of guest so...

Polarity Formation in Molecular Crystals as a Symmetry Breaking Effect

Abstract: The transition of molecular crystals into a polar state is modeled by a one-dimensional Ising Hamiltonian in multipole expansion and a suitable order parameter. Two symmetry breakings are necessary for the transition: the translational and the spin flip invariance—the former being broken by geometric constraints, the latter by the interaction of the first non-zero multipole with the n...

Orbital tuning of geomagnetic polarity time-scales

Milankovitch climate cyclicity and magnetic polarity stratigraphy are being successfully combined as a powerful geochronometer in the astronomical polarity timescale (APTS). The APTS for 0–5.23 Ma has been rapidly accepted as the definitive chronology for the Pliocene and Pleistocene against which even high precision radiometric dating is now calibrated. Extensions of astronomical calibration t...

Molecular Crystals and Liquid Crystals

Molecular Crystals and Liquid Crystals

The problem of finding the equilibrium shape of a small particle by the Wulff construction is reviewed briefly, with emphasis on its applications to liquid crystals. The proof of Wulff’s theorem is stated in a concise mathematical form. Some typical equilibrium shapes of liquid crystalline cirops are described. When there is orientational order of the molecules in the liquid crystal but no tran...