Calorimetric study of the cubic mesogen, ACBC(6)

The heat capacity of the cubic mesogen ACBC(16) was measured between 16 and 500 K by adiabatic calorimetry. As well as the known condensed phases, a new crystalline phase was found to undergo a glass transition at around 165 K. Phase transitions between crystal, SmC, cubic, and isotropic liquid phases took place at 399.16, 431.15, and 474.30 K, respectively. As in the case of ANBC, a broad hump was observed in the heat capacity of the isotropic liquid phase. The first order nature of the SmC-cubic phase transition was confirmed for the first time by the observation of supercooling of the cubic phase. The broad hump in the isotropic liquid phase was shown to extend to a low temperature side if the isotropic liquid was supercooled, suggesting that the event occurring at the hump is not directly related to the cubic-isotropic liquid phase transition.     

Adiabatic calorimetry of the metallomesogen purple cobalt stearate Co(O2CC17H35)2

The heat capacity of the metallomesogen purple cobalt stearate Co(O₂CC₁₇H₃₅)₂ has been measured by adiabatic calorimetry at temperatures between 16 and 420 K. This compound exhibits two crystalline phases (low temperature Cr2 and high temperature Cr1 phases), mesophase (M phase), and isotropic liquid (I phase). A third crystalline phase Cr3, which is entirely metastable with respect to all the others, is suggested by DSC studies. The Cr2-to-Cr1, Cr1-to-M, and M-to-I phase transitions occurred at 362.1, 380.9, and 400.4 K, respectively. The enthalpy and entropy gains at these phase transitions were determined. The mesophase is either smectic A or nematic.     

Dependence of intramolecular valence delocalization on crystal form in mixed-valence trinuclear iron phenylacetate [Fe 2 III FeIIO(PhCH2CO2)6(py)3]

A dependence of intramolecular valence delocalization on crystal form in mixed-valence trinuclear iron phenylacetate [Fe ₂ ^III Fe^IIO(PhCH₂CO₂)₆(py)₃] was found. This complex was obtained in two different crystal forms: a columnar and a needle crystal form. Mössbauer spectra of the columnar crystals show a temperature-dependent valence delocalization, while the needle crystals show a trapped mixed-valence state from a lower temperature up to room temperature.     

Mössbauer spectroscopic studies of MIIMIVS3 (MII=Sn,Pb; MIV=Sn,Ge, Hf) and PbSnS2Se

Temperature-dependent Mössbauer experiments have been carried out to examine the lattice dynamical properties of tin sites in Sn₂S₃ and its related compounds. The differences in the lattice parameters, estimated from the temperature dependence of the area intensities for the compounds, are attributed to the characteristics of their crystal structures.     

Vibrational isotope effect and molecular structure of M-Xy type molecules

A general theory on the vibrational isotope effect of linear MXY type molecules is presented. Here, XY denotes diatomic species such as CO and CN, while M typically represents a metal atom such as Li and Pt. It is shown that the MXY and MYX structures can be distinguished by comparing the isotope shift of the MXY (or MYX) molecule with that of free XY. Applications of the theory to problems of structure determination and band assignments are made to demonstrate its utility.     

Structural determination of carnosadine,a new cyclopropyl amino acid,from red alga Grateloupia carnosa

A new cyclopropyl amino acid, carnosadine, was isolated from red alga Grateloupia carnosa and the structure was determined to be 1-amino-2-guanidino-methylcylopropane-1-carboxylic acid from the results of NMR, mass spectrometry and coloring tests.     

Resonance Raman spectrum of selenium thin film

The resonance Raman spectrum of a selenium thin film at 20 K has been measured with the 514.5 nm excitation. A series of overtones, nv₇ (n = 1–5), v₂ + nv₇ (n = 0–3) and v₁₀ have been observed where v₇, v₂ and v₁₀ are the fundamental vibrations of the Se₈ ring molecule. The broadness of these bands at 20K suggests that the thin film contains randomly orientated Se₈ ring molecules.