Cyclopentanone in the Synthesis of Fused 4,7-Phenanthroline Derivatives

Catalytic condensation of cyclopentanone with arylmethylene(6-quinolyl)amines gave previously unknown 8-aryl-10,11-dihydro-9H-cyclopenta[a]-4,7-phenanthrolines.     

2'-O-[2-(guanidinium)ethyl]-modified oligonucleotides: stabilizing effect on duplex and triplex structures

[structure: see text] Oligonucleotides with a novel 2'-O-[2-(guanidinium)ethyl] (2'-O-GE) modification have been synthesized using a novel protecting group strategy for the guanidinium group. This modification enhances the binding affinity of oligonucleotides to RNA as well as duplex DNA (DeltaT(m) 3.2 degrees C per modification). The 2'-O-GE modified oligonucleotides exhibited exceptional resistance to nuclease degradation. The crystal structure of a palindromic duplex formed by a DNA oligonucleotide with a single 2'-O-GE modification was solved at 1.16 A resolution.     

Conditions favoring the polar weak ferromagnetic state in BiFeO<Subscript>3</Subscript>-type multiferroics

The crystal structure and magnetic properties of Bi_{1 − x} A _x FeO_{3 − x/2} (A = Ca, Sr, Pb, Ba), Bi_{1 − x} A _x (Fe_{1 − x} Ti _x )O₃, and Bi_{1 − x} A _x (Fe_{1 − x/2}Nb _x/2)O₃ solid solutions have been studied. It is shown that the homogeneous polar weak ferromagnetic state occurs in the vicinity of a morphotropic phase boundary in the systems where dopant ions lead to the reduction of the unit cell volume in the polar phase. In the case of A = Ca, the non-polar phase also exhibits weak ferromagnetism and the spontaneous magnetizations in the polar and nonpolar phases differ only slightly.     

On the creation of stable periodic behavior of parametrically excited dynamical systems

The problem of the realization of stable periodic behavior of dynamical systems is considered. It is shown analytically that in certain cases it is possible to achieve by parametric perturbation stable periodic behavior of systems that in the autonomous case possess only unstable oscillatory or stationary regimes or are in a stable equilibrium position.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 104, No. 3, pp. 507–512, September, 1995.     

Synthesis and stereoisomerism of the decahydroquinoline series N-oxides 6. X-ray diffraction study of 1,2e-dimethyl-4a-ethynyl-4e-hydroxy-trans-decahydroquinoline N-oxide hydrobromide

The results of x-ray diffraction analysis on 1,2e-dimethyl-4a-ethynyl-4e-hydroxy-trans-decahydroquinoline N-oxide hydrobromide corroborated the orientation of the substituents at the nitrogen atom that was determined previously from PMR data.For Communication 5, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 82–85, January, 1993.     

Synthesis of Amino and Hydroxy Derivatives of 4,7-Phenanthroline

Nitro-, dinitro-, and hydroxynitrophenyl-substituted 4,7-phenanthrolines were reduced with tin(II) chloride in a mixture of acetic and nitric acids to obtain amino, diamino, and hydroxy derivatives of 4,7-phenanthroline. When heated with aromatic aldehydes, the products form azomethines of the 4,7-phenanthroline series.