Synthesis and properties of unsymmetrically extended π-electronic conjugation system of octaethylporphyrin(Ni)-dihexybithiophene-octaethylporphyrin(Pd) connected with diacetylene linkage

Orientational isomers of the diacetylene-group connected dihexybithiophene (DHBTh) derivatives have been synthesized, in which the different octaethylporphyrin (OEP(M); M=Ni or Pd) rings are attached at the ends. Reflecting the unsymmetrical structural feature, the peculiar electronic properties of the extended OEP(Ni)-DHBTh-OEP(Pd) system were observed.     

Spectrophotometric determination of formation constants of various types of complexes by use of another competing ligand

A method has been developed for determining the formation constants of various colored complexes, ML and ML₂, and their protonated forms, spectrophotometrically, by measuring the absorbance of all forms of the colored complexes in the absence and presence of another ligand, Y, which forms the colorless complex MY, with a known formation constant. This method is based on the competition between the two ligands, L and Y, for the metal ion. An experimental test has been done for the Zn(II)-4-(2-pyridylazo)resorcinol (PAR) (H₂L) system by using nitrilotriacetic acid (NTA) as another ligand, Y. The results showed that the concentrations of PAR used were suitable for the study of 1:2 complexes, ZnL₂, ZnL(HL) and Zn(HL)₂, but were too high to study the 1:1 complexes. With the aid of the formation constants of ZnL and ZnHL determined previously, the experimental data gave an approximate value for the formation constant of ZnY (Y = NTA) which agreed with the published value.     

NbCl5 a multifunctional reagent for the synthesis of new halogenated aminoquinoline compounds through innovative one-pot reaction and the acidochromism effect

This paper describes an original one-pot way to synthesize nine new halogenated aminoquinoline derivatives using reactions conducted by niobium pentachloride. Subsequently, we describe an efficient and selective reduction reaction of nitroquinolines using niobium pentachloride and zinc, producing important compounds in the organic synthesis.The results showed that it is an important tool to synthesize these compounds, besides being time- and resources-saving and generating good yields. A quick study of acidochromism was performed.     

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.     

Enantioselective cyclopropanation reaction using a conformationally fixed pyridinium ylide through a cation-π interaction

Using a chiral pyridinium ylide with a fixed conformation through a cation-π interaction performs enantioselective cyclopropanation of electron-deficient olefins. ¹H NMR, X-ray structural analysis and DFT calculations elucidated the self-complexation and the face-to-face arrangement between the pyridinium and the phenyl rings. The absolute configuration of the product was determined after conversion into a bicyclic cyclopropane derivative.     

Magnetic transitions of single-component molecular metal [Au(tmdt)2] and its alloy systems

A single-component molecular conductor [Au(tmdt)2] (tmdt = trimethylenetetrathiafulvalenedithiolate) undergoes an antiferromagnetic phase transition at unprecedentedly high temperature (TN = 110 K). Black microcrystals of alloys, [Ni1-xAux(tmdt)2] (0.0 < x < 1.0) were prepared. The Au-rich system exhibited an antiferromagnetic transition. Metallic single crystal was obtained for x = 0.25.