Magnetoelectric ordering of BiFeO3 from the perspective of crystal chemistry

In this paper we examine the role of crystal chemistry factors in creating conditions for formation of magnetoelectric ordering in BiFeO3. It is generally accepted that the main reason of the ferroelectric distortion in BiFeO3 is concerned with a stereochemical activity of the Bi lone pair. However, the lone pair is stereochemically active in the paraelectric orthorhombic beta-phase as well. We demonstrate that a crucial role in emerging of phase transitions of the metal-insulator, paraelectric-ferroelectric and magnetic disorder-order types belongs to the change of the degree of the lone pair stereochemical activity - its consecutive increase with the temperature decrease. Using the structural data, we calculated the sign and strength of magnetic couplings in BiFeO3 in the range from 945 C down to 25 C and found the couplings, which undergo the antiferromagnetic-ferromagnetic transition with the temperature decrease and give rise to the antiferromagnetic ordering and its delay in regard to temperature, as compared to the ferroelectric ordering. We discuss the reasons of emerging of the spatially modulated spin structure and its suppression by doping with La3+.Comment: 18 pages, 5 figures, 3 table

Vibrational properties of the one-component σ\sigma phase

A structural model of a one-component $\sigma$-phase crystal has been constructed by means of molecular dynamics simulation. The phonon dispersion curves and the vibrational density of states were computed for this model. The dependence of the vibrational properties on the thermodynamical parameters was investigated. The vibrational density of states of the $\sigma$-phase structure is found to be similar to that of a one-component glass with icosahedral local order. On the basis of this comparison it is concluded that the $\sigma$ phase can be considered to be a good crystalline reference structure for this glass

Compounds possessing affinity at 5ht1-type receptors and use thereof in therapy of cns disorders

Compounds of formula (I) and pharmaceutically acceptable salts thereof are disclosed: (I) wherein: A is optionally substituted phenyl, naphthyl, indolyl, quinolinyl, quinazolinyl, indazolyl, isoquinolinyl or benzofuranyl; X is carbon, Y is CH and is a double bond; or X is CH, Y is CH2 or oxygen and is a single bond; or X is nitrogen, Y is CH2 and is a single bond; R1 is halogen, hydroxy, cyano, C1-6alkyl, haloC1-6alkyl or C1-6alkoxy; a is 0, 1, 2, 3 or 4; R2 and R3, together with the nitrogen atom to which they are attached, form a nitro group or an optionally substituted 3 to 7 membered heterocyclic group, or R2 and R3 are independently hydrogen, aroyl, C1-6alkyl, C1-6alkanoyl, fluoroC1-6alkanoyl, C1-6alkylsulfonyl, fluoroC1-6alkylsulfonyl, carbamoyl, C1-6alkylcarbamoyl, arylC1-6alkyl or a group CO(CH2)bNR4R5 wherein b is 1, 2, 3 or 4 and R4 and R5 are independently hydrogen or C1-6alkyl, or R4 and R5, together with the nitrogen atom to they are attached, form part of an optionally substituted 3 to 7 membered heterocyclic group. Methods of preparing the compounds and uses of the compounds in therapy, in particular for CNS disorders such as depression and anxiety, are also disclosed

Compounds possessing affinity at 5ht1-type receptors and use thereof in therapy of cns disorders

Compounds of formula (I) and pharmaceutically acceptable salts thereof are disclosed: (I) wherein: A is optionally substituted phenyl, naphthyl, indolyl, quinolinyl, quinazolinyl, indazolyl, isoquinolinyl or benzofuranyl; X is carbon, Y is CH and is a double bond; or X is CH, Y is CH2 or oxygen and is a single bond; or X is nitrogen, Y is CH2 and is a single bond; R1 is halogen, hydroxy, cyano, C1-6alkyl, haloC1-6alkyl or C1-6alkoxy; a is 0, 1, 2, 3 or 4; R2 and R3, together with the nitrogen atom to which they are attached, form a nitro group or an optionally substituted 3 to 7 membered heterocyclic group, or R2 and R3 are independently hydrogen, aroyl, C1-6alkyl, C1-6alkanoyl, fluoroC1-6alkanoyl, C1-6alkylsulfonyl, fluoroC1-6alkylsulfonyl, carbamoyl, C1-6alkylcarbamoyl, arylC1-6alkyl or a group CO(CH2)bNR4R5 wherein b is 1, 2, 3 or 4 and R4 and R5 are independently hydrogen or C1-6alkyl, or R4 and R5, together with the nitrogen atom to they are attached, form part of an optionally substituted 3 to 7 membered heterocyclic group. Methods of preparing the compounds and uses of the compounds in therapy, in particular for CNS disorders such as depression and anxiety, are also disclosed

Piperidine and piperazine derivatives possessing affinity at 5ht-1 type receptors

Compounds of formula (I) and pharmaceutically acceptable salts thereof are disclosed:wherein A is optionally substituted phenyl, indolyl, quinolinyl, quinazolinyl, indazolyl or isoquinolinyl; X is carbon, Y is CH and is a double bond; or X is CH, Y is CH2 or oxygen and is a single bond; or X is nitrogen, Y is CH2 and is a single bond; R1 is halogen, cyano, nitro, C1-6 alkyl, haloC1-6 alkyl, C1-6 alkoxy, C3-7 heterocyclylC1-6 alkyl, C3-7 heterocyclyl C1-6 alkoxy; a is 0, 1, 2, 3 or 4; R2 is either: halogen, -CN, an optionally substituted C3-7 cycloalkyl, an optionally substituted aryl or an optionally substituted C-linked 3-7 membered heterocyclic group; or a group -(Z)b-B wherein: (i) Z is oxygen, CH2, C=O, SO2 or C=N-OR3 wherein R3 is hydrogen or C1-6 alkyl; b is 1, 2, or 3; and B is hydrogen, C1-6 alkyl, C3-7 cycloalkyl, C1-6 alkoxy or NR4R5 wherein R4 and R5 are independently hydrogen, C1-6 alkyl, C3-7 cycloalkyl, C1-6 alkanoyl, fluoroC1-6 alkanoyl, C1-6 alkylsulfonyl, fluoroC¿1-6 alkylsulfonyl, carbamoyl or C1-6 alkylcarbamoyl, or R4 and R5, together with the nitrogen atom to which they are attached, form part of an optionally substituted 3 to 7 membered heterocyclic group; or (ii) Z is oxygen, CH or CH2, b is 1, and B forms the rest of an aryl or a C3-7 heterocyclic group fused to the phenyl ring; excluding 1-[2-[2-(phenylmethyl)phenoxy]ethyl]-4-[(2,3,4-trimethoxyphenyl)methyl]-piperazine and pharmaceutically acceptable salts thereof, and N-[4-[2-[4-[(3,4-dimethoxyphenyl)methyl]-1-piperazinyl]ethoxy]phenyl]-ethanesulfonamide and pharmaceutically acceptable salts thereof. Methods of preparing the compounds and uses of the compounds in therapy, in particular for CNS disorders such as depression and anxiety, are also disclosed

Piperidine and piperazine derivatives possessing affinity at 5ht-1 type receptors

Compounds of formula (I) and pharmaceutically acceptable salts thereof are disclosed:wherein A is optionally substituted phenyl, indolyl, quinolinyl, quinazolinyl, indazolyl or isoquinolinyl; X is carbon, Y is CH and is a double bond; or X is CH, Y is CH2 or oxygen and is a single bond; or X is nitrogen, Y is CH2 and is a single bond; R1 is halogen, cyano, nitro, C1-6 alkyl, haloC1-6 alkyl, C1-6 alkoxy, C3-7 heterocyclylC1-6 alkyl, C3-7 heterocyclyl C1-6 alkoxy; a is 0, 1, 2, 3 or 4; R2 is either: halogen, -CN, an optionally substituted C3-7 cycloalkyl, an optionally substituted aryl or an optionally substituted C-linked 3-7 membered heterocyclic group; or a group -(Z)b-B wherein: (i) Z is oxygen, CH2, C=O, SO2 or C=N-OR3 wherein R3 is hydrogen or C1-6 alkyl; b is 1, 2, or 3; and B is hydrogen, C1-6 alkyl, C3-7 cycloalkyl, C1-6 alkoxy or NR4R5 wherein R4 and R5 are independently hydrogen, C1-6 alkyl, C3-7 cycloalkyl, C1-6 alkanoyl, fluoroC1-6 alkanoyl, C1-6 alkylsulfonyl, fluoroC¿1-6 alkylsulfonyl, carbamoyl or C1-6 alkylcarbamoyl, or R4 and R5, together with the nitrogen atom to which they are attached, form part of an optionally substituted 3 to 7 membered heterocyclic group; or (ii) Z is oxygen, CH or CH2, b is 1, and B forms the rest of an aryl or a C3-7 heterocyclic group fused to the phenyl ring; excluding 1-[2-[2-(phenylmethyl)phenoxy]ethyl]-4-[(2,3,4-trimethoxyphenyl)methyl]-piperazine and pharmaceutically acceptable salts thereof, and N-[4-[2-[4-[(3,4-dimethoxyphenyl)methyl]-1-piperazinyl]ethoxy]phenyl]-ethanesulfonamide and pharmaceutically acceptable salts thereof. Methods of preparing the compounds and uses of the compounds in therapy, in particular for CNS disorders such as depression and anxiety, are also disclosed