Recent advances in calorimetry and thermal analysis: Collected papers from the 8th international and 10th Japan–China joint symposium on calorimetry and thermal analysis (CATS-2017)

Journal of Thermal Analysis and Calorimetry -     

Hydrogen-Bonded Polyrotaxane Cation Structure in Nickel Dithiolate Anion Radical Salts: Ferromagnetic and Semiconducting Behavior Associated with Structural Phase Transition

The pseudo-polyrotaxane structure of [(H-bpy⁺)- (DB-24-crown-8)]_∞ (H-bpy⁺ = monoprotonated 4,4-bipyridinium; DB-24-crown-8 = dibenzo-24-crown-8) has been incorporated into the anion radical salt [Ni(dmit)₂]⁻ (dmit²⁻ = 1,3-dithiole-2-thione-4,5-dithiolate). (H-bpy⁺)(DB-24-crown-8)[Ni(dmit)₂]⁻ crystallized as two polymorphs, crystals 1 and 2 . Crystal 1 was found to have a lower density and looser packing structure in which H-bpy⁺ forms a one-dimensional hydrogen-bonding chain that passes though the crown ether ring of DB-24-crown-8. DB-24-crown-8 adopts a U-shaped conformation in which two phenylene rings sandwich one of the pyridyl rings of H-bpy⁺ to stabilize the structure. The [Ni(dmit)₂]⁻ anions are arranged in a layer parallel to the (10) plane with uniform side-by-side interactions. A structural phase transition was observed at 235 K, accompanied by ordering of the polyrotaxane structure. In crystal 1 , at 173 K, H-bpy⁺ is twisted around the central C−C bond, which perturbs the arrangement of [Ni(dmit)₂]⁻ through short C−H⋅⋅⋅S contacts. As a result, the semiconducting behavior, with an activation energy of 0.21 eV, becomes insulating below 235 K. The crystal exhibits ferromagnetic interactions because of the weak side-by-side interactions between [Ni(dmit)₂]⁻ anions. Crystal 2 has a similar pseudo-polyrotaxane structure but showed no phase transition. This suggests that the looser crystal packing in crystal 1 induces the structural change of the pseudo-polyrotaxane, perturbing the electron system of [Ni(dmit)₂]⁻.     

Chiral Benzazaborole-Catalyzed Regioselective Sulfonylation of Unprotected Carbohydrate Derivatives

Chiral benzazaborole-catalyzed regioselective sulfonylations of unprotected carbohydrate derivatives have been developed. This methodology enables direct regioselective functionalization of the secondary OH group in carbohydrate in the presence of the primary OH group. By using the chiral organoboron catalysis, kinetic resolution of the carbohydrate derivatives was also achieved.     

Resolution enhancement of pump–probe microscope with an inverse-annular filter

Optical Review - Optical pump–probe microscopy can provide images by detecting changes in probe light intensity induced by stimulated emission, photoinduced absorbance change, or...     

Application of alkoxy-λ6-sulfanenitriles as strong alkylating reagents

Alkoxy-λ⁶-sulfanenitriles were found to be versatile alkylating reagents toward various nucleophiles bearing at least one proton such as methanol, phenol, thiophenols, carboxylic acids, p-toluenesulfonic acid, hydrochloric acid, and primary and secondary amines. Reactivity of the alkoxy group of the λ⁶-sulfanenitriles showed an opposite trend to the usual S_N2 character, i.e. Me ( 1a ), Pr ( 1b ), and Bu ( 1d ) ≪ i-Pr ( 1c ). In the presence of p-TsOH, alkyl tosylates were predominantly formed instead of the alkylation products of nucleophiles. In addition, even a sterically hindered substrate, neopentyloxy-λ⁶-sulfanenitrile, was found to undergo an S_N2 reaction toward thiophenol without any rearrangement product to give neopentyl phenyl sulfide in good yield. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:193–198, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20006     

Control of photochemistry of stilbazolium ion by adsorption to poly(potassium vinylsulfate) and to hectorite clay

Adsorption or intercalation of trans-1-methyl-4-(2-phenylvinyl)pyridinium ion (stilbazolium ion, SB ( 1 )) to a polyelectrolyte, i. e., poly(potassium vinylsulfate) (PVSK), and to a hectorite clay is studied and its effect on the photochemistry of SB examined. trans-cis Photoisomerization of SB molecularly adsorbed to PVSK proceeds efficiently as with free SB in water, while that of SB molecularly intercalated in the clay is markedly suppressed. Photodimerization proceeds efficiently with SB intercalated in the clay in the aggregated form. Overall photodecoloration, however, proceeds more efficiently with SB adsorbed to PVSK under multiple adsorption conditions apparently due to the higher mobility of PVSK-adsorbed SB compared to that of clay-intercalated SB.     

Preparation,structure, and optical properties of chiral sulfoxides and disulfoxide with a trithiole ring

Optically active 4,9‐diethyl[1,4]‐dithiino[5,6‐f]benzo[1,2,3]trithiole 5‐oxide ( 3 ) and 4,9‐diethyl[1,4]dithiino[5,6‐f]benzo[1,2,3]trithiole 5,8‐dioxide ( 4 ) were obtained by the asymmetric oxidation of 6,11‐diethyl[1,4]dithiino[5,6‐h]benzo[1,2,3,4,5]pentathiepin ( 1 ). The reaction was accompanied by desulfurization and ring‐contraction reactions of the pentathiepin ring. Similarly, optically active 4,8‐diethyl[1,3]dithiolo[4,5‐f]benzo[1,2,3]trithiole 5‐oxide ( 7 ) was produced by the analogous asymmetric oxidation of 6,10‐diethyl[1,3]dithiolo[4,5‐h]benzo[1,2,3,4,5]pentathiepin ( 2 ). The specific rotations of 3 , 4 , and 7 were measured in chloroform, and their optical purity was verified by ¹H NMR with a shift reagent [Eu(hfc)₃]. The structures of 4 and 7 were determined by X‐ray crystallography using Cu Kα radiation, and the absolute configuration of the sulfinyl group was examined based on the Flack parameter, which revealed that 4 has an RR configuration, while 7 has an S configuration. The circular dichroism spectra of 3 , 4 , and 7 were measured in chloroform. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:88–94, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10104