pK(a) Switching induced by the change in the pi-conjugated system based on photochromism

Two diarylethene derivatives 1 a and 2 a containing a 2,5-diaryl-3-thienyl group have been designed and synthesized. The pK(a) values of these compounds change upon photoirradiation. They have a phenol group as a proton source and a pyridinium group as an acceptor unit at each end of the pi-conjugated chain. The cyclization/cycloreversion reactions can be used to control the length of the pi-conjugated chain between the proton source and the acceptor. The change in the pi-conjugated chain length caused the pK(a)-switching.     

Characterization of cationic diarylethene by electron spin resonance and absorption spectra-ratio of open/closed-ring isomers

Electrochemical cyclization/cycloreversion reactions of a diarylethene, 1,2-bis(3-methyl-2-thienyl)perfluorocyclopentene, are examined experimentally by electron spin resonance (ESR) and absorption spectra. To understand the ESR spectrum, the hyperfine coupling constants are calculated by the density functional theory (DFT) with the B3LYP exchange-correlation functional. The averaged values of the hyperfine coupling constants are approximated by imposing the C(2) symmetry on the structure of the diarylethene. We found that the spectral width of the ESR is significantly different between the open- and closed-ring isomers. This is due to the difference in the pi-conjugation between two isomers. The ESR spectral width analysis could, thus, be used to identify the isomerization of the radical species, which involve the change of the pi-conjugation. The experimentally observed spectrum is found to be the mixture of the open- and closed-ring isomers of the diarylethene. The excitation energies of the cationic diarylethenes are further identified by the SAC-CI calculations.     

Investigation of in situ oxalate formation from 2,3-pyrazinedicarboxylate under hydrothermal conditions using nuclear magnetic resonance spectroscopy

We have investigated the assembly of a two-dimensional coordination polymer, Nd(2)(C(6)H(2)N(2)O(4))(2)(C(2)O(4))(H(2)O)(2), that has been prepared from the hydrothermal reaction of Nd(NO(3))(3)·6H(2)O and 2,3-pyrazinedicarboxylic acid (H(2)pzdc). In situ oxalate formation as observed in this system has been been investigated using (1)H and (13)C nuclear magnetic resonance spectroscopy, and a pathway for C(2)O(4)(2-) anion formation under hydrothermal conditions has been elucidated. The oxalate ligands found in Nd(2)(C(6)H(2)N(2)O(4))(2)(C(2)O(4))(H(2)O)(2) result from the oxidation of H(2)pzdc, which proceeds through intermediates, such as 2-pyrazinecarboxylic acid (2-pzca), 2-hydroxyacetamide, 3-amino-2-hydroxy-3-oxopropanoic acid, 2-hydroxymalonic acid, 2-oxoacetic acid (glyoxylic acid), and glycolic acid. The species are generated through a ring-opening that occurs via cleavage of the C-N bond of the pyrazine ring, followed by hydrolysis/oxidation of the resulting species.     

Single component transparent free‐standing films based on polyhedral octasilicate‐core dendrimers bearing carbazole terminal groups and their emission properties

9H‐carbazole‐9‐ethyl and 9H‐carbazole‐9‐hexyl‐terminated polyhedral octasilicate (OS)‐core dendrimers, denoted as OS‐C2‐Cz and OS‐C6‐Cz, respectively, were prepared by ring‐opening reaction and subsequent condensation of octakis(propenyl succinicanhydrido)polyhedral octasilicate (OS‐SA) with 9H‐carbazole‐9‐ethanol (Cz‐C2‐OH) and 9H‐carbazole‐9‐hexanol (Cz‐C6‐OH), respectively. Both the dendrimers formed optical transparent coating films. In particular, the coating film of OS‐C2‐Cz was easily peeled off from a substrate and formed a free‐standing film. The results of X‐ray diffraction and differential scanning calorimeter suggest that the films of OS‐C2‐Cz and OS‐C6‐Cz were amorphous. Thermogravimetric analysis of OS‐C2‐Cz and OS‐C6‐Cz showed 10 wt % weight losses at 374 and 383 °C, respectively. Photoluminescence property revealed that the carbazole group in OS‐C2‐Cz is prevented the excimer formation, while the carbazole group in OS‐C6‐Cz formed the excimer. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 628–633     

Alleviation of the chlorpromazine-induced muscular tissue damage by β-cyclodextrin complexation

From the gross and histological examinations, -cyclodextrin (-CyD) was found to reduce the muscular tissue damage produced by chlorpromazine hydrochloride (CPZ) onM. vastus lateralis in rabbits. The protective effect of -CyD may be attributable to the decrease in affinity of CPZ to the tissue membrane through inclusion complexation. There was no appreciable difference in the pharmacokinetic and pharmacodynamic behaviors between CPZ and its -CyD complex in rabbits. These results suggest that -CyD is useful to reduce the local tissue toxicity of CPZ without altering the pharmacological efficacy.     

Trifluoromethyl trifluoromethanesulfonate (CF3SO2OCF3)

Trifluoromethyl trifluoromethanesulfonate ($\text{1}$) was synthesized by the reaction of silver trifluoromethanesulfonate with trifluoromethyl iodide in a benzene solution. Reaction of $\text{1}$ with an enamine gave trifluoromethanesulfonyl compound. This is the first example of SO₂-O bond fission of alkyl trifluoromethanesulfonate.     

Synthesis of perfluorochemicals for use as blood substitutes,part II: electrochemical fluorination of partly fluorinated compounds

Electrochemical fluorination of 2-methoxy-1,1,1-trifluoro-2-(F-methyl) octane gave the corresponding perfluorinated ether in 27% yield, along with cyclic by-products in 9%. A mixture of partly fluorinated tertiary amines, consisting of 1-dipropylamino-F-1-propene and 1-dipropylamino-2-hydryl-F-propane, did not afford a superior yield of tri(F-propyl)amine compared to the unfluorinated tripropylamine. 1-Diethylamino-2-(F-methyl)-F-1-pentene was fluorinated to give the corresponding F-tertiary amine in fairly good yields, together with 1-di(F-ethyl)amino-2-hydryl-2-(F-methyl)-F-pentane and their fragmented products. The study indicates that blocking of the α-carbon atom of an ether with F-methyl groups seems to reduce fragmentation, resulting in good yields of an unrearranged product. However, partial fluorination of a tertiary amine prior to electrochemical fluorination rather allows high yields of undesired by-products, as far as our experiments were concerned.