The phase behavior of heptaethylene glycol dodecyl ether (C12E7) and its aqueous mixture was investigated by means of differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy in the temperature range from -20 to 70 °C. Phase boundaries among various phases including mesomorphic phases were determined on the basis of DSC thermograms, from which the binary phase diagram of this mixture system was constructed. According to the phase diagram, the mixture with the composition of 31 wt % H2O exhibits the following phase sequence with increasing temperature: solid f H1 (normal hexagonal) f V1 (normal bicontinuous-type cubic) f LR (lamellar) f liquid. FT-IR measurements for the mixture with this composition revealed the following features concerning the conformational structure of the C12E7 molecule and the interaction between the surfactant and D2O in each phase. In the solid phase, the polyoxyethylene (POE) chain of the surfactant molecule has a rather extended structure with a trans-rich conformation, in contrast to the case of pure C12E7, in which a helical structure is dominant. When the solid phase transforms to the H1 phase, the hydrogen-bond interaction between C12E7 molecules and between C12E7 and water are both weakened, and the fraction of gauche-conformer in the POE chain increases, whereas the alkyl chain adjacent to the POE chain remains, taking a rather trans-zigzag conformation. The enhanced fraction of gauche-conformer in the POE chain suggests that the POE chain has a helical structure in this phase. The increase in temperature within the H1 region causes a conformational change in both the POE chain and the alkyl chain of the surfactant to a more disordered structure. Among the phases of V1, LR, and liquid, no significant difference is seen in the conformational structure and interaction with water molecules of the surfactant.

Two different types of hydrogen bond, which are classified into a familiar OH-O and a relatively weak OH-π one, have been compared in the 1:1 hydrogen-bonded 2,3-benzofuran clusters with water and methanol molecules. By applying fluorescence-detected infrared spectroscopy and dispersed fluorescence spectroscopy, two isomers having different types of hydrogen bonds are distinguished. From the calculated stabilization energy as well as the frequency shift of the OH stretching vibration in each cluster, these two isomers are almost equally stable, although that of OH-π type is usually thought to be relatively weak. It is suggested that the origin of the weak OH-O hydrogen bond is derived from the lower availability for a hydrogen bond acceptor on the oxygen atom of a heteroaromatic ring, which is attributed to the larger furan aromaticity.

A facile synthetic route to Ni(0)(NHC) 2 from stable Ni(II)(acac) 2 was established without common but labile Ni(0) precursors. The intermediate is a divalent mono-NHC adduct of Ni(acac) 2 , Ni(NHC)(acac) 2 . Reduction of Ni(NHC)(acac) 2 in both the presence and absence of an NHC ligand gave Ni(NHC) 2 in ca. 90% and 40% conversions, respectively. Ni(NHC) 2 , especially with bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, has strong Ni-C(carbene) bonds and remarkable anagostic Ni-H(methyl) interactions, stabilizing its 14e unsaturated structure.