3]rotaxane synthesized via covalent bond formation can recognize cations forming a sandwich structure

A novel [3]rotaxane composed of two 25-membered crownophanes and one axle molecule having two anthryl end groups was successfully synthesized via covalent bond formation followed by aminolysis, and can incorporate caesium ion into the space between the two macrocycles as a 1 : 1 sandwich-type complex, whereas it makes a 1 : 2 complex with lithium ion.     

A triple-injection method for microchip electrophoresis

We report here a novel triple injection method for microchip electrophoresis (micro-CE) that results in a higher intensity of DNA peaks. This new method includes a triple-repeated process of a combination of a sample loading voltage and a separation voltage in each interval, namely (loading time) + (separation time) + (loading time) + (separation time) + (loading time), prior to electrophoretic separation. All these injections were electrokinetically controlled by a software. Although the usual sample injection, which included the process of one 60 s electrokinetically application, was limited by the amount of sample, peaks of 40% higher intensity were obtained using the new method within half of the conventional injection time compared to the conventional method. Maximum peak intensity was successfully achieved with integration of the intensities of the triple-repeated peaks by adjusting the application period of the separation voltage. Repetition of the sample loading voltage for an adjusted period with a further adjusted period of separation voltage in each interval may be an effective method for injection of samples that results in peaks with higher intensity.     

The reducive amination of phthalaldehyde by tetracarbonylhydridoferrate : Synthesis of 2-arylisoindoles

Phthalaldehyde reacted with primary amines in the presence of tetracarbonylhydridoferrate under mild conditions to give 2-substituted isoindoles and/or isoindolines in good to excellent yields. Aliphatic amines gave selectively the isoindolines but aromatic amines had a great tendency to the isoindoles. 2-(2-Tolyl)-, 2-(4-tolyl)-, 2-(4-methoxyphenyl)-, 2-(3-chlorophenyl)-, 2-(4-chlorophenyl)- and 2-(3,4-dichlorophenyl)-isoindole were prepared by this method.     

Triplet diphenylcarbenes protected by (trimethylsilyl)ethynyl groups

(2,4,6-Tribromophenyl)(4-tert-butyl-2,6-dimethylphenyl)diazomethane (1a) was shown to be stable enough to survive Sonogashira coupling reaction conditions at an elevated temperature and gave not only a para-monosubstituted product, (4-trimethylsilylethynyl-2,6-dibromophenyl)(4-tert-butyl-2,6-dimethylphenyl)diazomethane (1b), but also a disubstituted one, [2,4-bis(trimethylsilylethynyl)-6-bromophenyl](4-tert-butyl-2,6-dimethylphenyl)diazomethane (1c), and a trisubstituted product, [2,4,6-tris(trimethylsilylethynyl)phenyl](4-tert-butyl-2,6-dimethylphenyl)diazomethane (1d). Triplet diphenylcarbenes (DPCs) generated by photolysis of those ethynylated diphenyldiazomethanes were characterized by ESR and UV-vis spectroscopies at low temperature and laser flash photolysis techniques in solution at room temperature. Although ESR data indicated that ethynyl groups at the ortho positions are likely to stabilize triplet DPCs both sterically and electronically more effectively than o-bromine groups, kinetic studies suggested that the stability of triplet DPCs is not increased by o-ethynyl groups, as opposed to o-bromine groups. It is likely that triplet DPCs decay by interacting with the o-ethynyl groups.     

A study of ADMET polyethylene with 21-carbon branches on every 15th compared to every 19th carbon: What a difference four extra backbone methylenes make

Precision polyethylenes with 21-carbon alkyl branches precisely spaced on every either 15th or 19th carbon along the polymer backbone lead to the formation of two kinds of lamellae, yielding different thicknesses during the crystallization process. Thinner lamellae originate from side-chain crystallization, whereas thicker lamellae are formed by cocrystallization of the branch and the main chain. Side-chain crystallization (separate from main chain crystallization) is favored when the branch is placed on every 15th carbon. Cocrystallization (side chain with main chain) is favored with the branch on every 19th carbon. Both form stable hexagonal crystal units. A branch spacing separation of just four carbons along the main chain makes a remarkable difference in crystallization behavior. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3090–3096     

Temperature-sensitive photoluminescence of CdSe quantum dot clusters

The formation of narrow size dispersed and nanometer size aggregates (clusters) of cadmium selenide (CdSe) quantum dots (QDs) and their temperature-sensitive photoluminescence (PL) spectral properties close to room temperature (298 K) are discussed. CdSe QDs formed stable clusters with an average diameter of approximately 27 nm in the absence of coordinating solvents. Using transmission electron microscopy (TEM) imaging, we identified the association of individual QDs with 2-5 nm diameters into clusters of uniform size. A suspension of these clusters in different solvents exhibited reversible PL intensity changes and PL spectral shifts which were correlated with temperature. Although the PL intensity of CdSe QDs encapsulated in host matrixes and the solid state showed a response to temperature under cryogenic conditions, the current work identified for the first time QD clusters showing temperature-sensitive PL intensity variations and spectral shifts at moderate temperatures above room temperature. Temperature-sensitive reversible PL changes of clusters are discussed with respect to reversible thermal trapping of electrons at inter-QD interfaces and dipole-dipole interactions in clusters. Reversible luminescence intensity variations and spectral shifts of QD clusters show the potential for developing sensors based on QD nanoscale assemblies.     

Effects of phosphatidylserine and phosphatidylethanolamine content on partitioning of triflupromazine and chlorpromazine between phosphatidylcholine-aminophospholipid bilayer vesicles and water studied by second-derivative spectrophotometry

To assess the affinity of psychotropic phenothiazine drugs, triflupromazine (TFZ) and chlorpromazine (CPZ), for the membranes of central nervous system and the other organs in the body, the partition coefficients (Kps) of these drugs to phosphatidylcholine (PC)-phosphatidylserine (PS) and PC-phosphatidylethanolamine (PE) small and large unilamellar vesicles (SUV, LUV) were examined by a second-derivative spectrophotometric method, since PS is abundantly contained in the membranes of the central nervous system and PE is distributed widely in the membranes of the organs in the body. Size and preparation methods of the vesicles did not affect the Kp values at each aminophospholipid content suggesting that the partition of the phenothiazine drugs was not affected by the structural differences in the vesicles such as their curvature or asymmetric distribution of the phospholipids between the outer and inner layers of the bilayer membranes. However, the Kp values of both drugs increased remarkably according to the PS content in the bilayer membranes, i.e., the Kp values for the vesicles of 30 mol% PS content were about 3 times of that for the vesicles of PC alone, while both Kp values slightly reduced with the increase in the content of PE in the bilayer membranes of PC-PE vesicles. The results indicate that both drugs have higher affinity for the PC-PS bilayer membranes than for the PC and PC-PE membranes, which can offer an evidence for the fact that TFZ and CPZ are predominantly distributed and accumulated in the brain and nerve cell membranes that contain PS abundantly.     

Synthesis of 1‐acyl‐2‐oxo‐3‐pyrrolidinecarbonitriles by the reaction of 2‐acylamino‐4,5‐dihydro‐3‐furancarbonitriles with sodium iodide

The reaction of 2‐acylamino‐4,5‐dihydro‐3‐furancarbonitriles 1 with sodium iodide in N,N‐dimethyl‐formamide gave the corresponding 1‐acyl‐2‐oxo‐3‐pyrrolidinecarbonitriles 2 in good yields. Successive treatment of 1 with titanium(IV) chloride and potassium carbonate resulted in the formation of N‐acyl‐1‐cyanocyclopropanecarboxamides 4 . The same compounds 2 were also obtained by treatment of 4 with sodium iodide. The starting compounds 1 were synthesized by the reaction of 2‐amino‐4,5‐dihydro‐3‐furan‐carbonitrile with acyl chlorides in pyridine.     

First catalytic asymmetric hydrophosphonylation of cyclic imines: Highly efficient enantioselective approach to a 4-thiazolidinylphosphonate via chiral titanium and lanthanoid catalysts

The catalytic and enantioselective hydrophosphonylation of a cyclic imine, namely the 3-thiazoline 1, is described. We have discovered a highly efficient enantioselective de novo approach to the pharmaceutically interesting 4-thiazolidinylphosphonate 2 using either titanium or lanthanoid chiral catalysts, which gives excellent enantiomeric purities (up to 98 %ee) and high chemical yields.