ABSTRACT Reactivity of [Pd(CH3)(CO)(PriDAB)]+[B{3,5-(CF3)2C6H3}4]- (1), where PriDAB = 1,4-diisop... more ABSTRACT Reactivity of [Pd(CH3)(CO)(PriDAB)]+[B{3,5-(CF3)2C6H3}4]- (1), where PriDAB = 1,4-diisopropyl-1,4-diaza-1,3-butadiene, toward alkynes and carbon monoxide was investigated. While the reaction of 1 with phenylacetylene produced stereoregular homopolymer, a stoichiometric insertion of 1-phenyl-1-propyne and 2-butyne into the Pd−acyl bond yielded the palladacycles 2 and 3; subsequent reaction with CO resulted in the formation of novel complexes 4 and 5, which represent the first experimental evidence of a key intermediate in alkyne cyclocarbonylation processes.
We give an algorithm which goal is to find the energy barrier between a given pair of points in a... more We give an algorithm which goal is to find the energy barrier between a given pair of points in a graph which represents the conformational space of a molecule. If the conformational space is homeomorphic to an -dimensional torus, then the graph can be chosen of a particular form. The UTN software, which implements the algorithm in this case, is described in detail. Finally we focus on applications: to show how UTN works, some examples are carried on in detail, with the additional support of graphical animation1 in the twodimensional case. The source code of the program and some data of the examples are available to the reader.
Insertion of 1,2‐disubstituted alkynes into [Pd(CH3)(CO)(BIOX)]+[B{3,5‐(CF3)2C6H3}4]− (1), where ... more Insertion of 1,2‐disubstituted alkynes into [Pd(CH3)(CO)(BIOX)]+[B{3,5‐(CF3)2C6H3}4]− (1), where BIOX=(4S,4′S)‐(−)‐4,4′,5,5′‐tetrahydro‐4,4′‐bis(1‐methylethyl)‐2,2′‐bioxazole, leads to the formation of five‐membered palladacycles, which, by reaction with carbon monoxide, produce a mixture of two diastereomeric forms of a palladium complex containing an η3‐allylic γ‐lactone ligand. On leaving the mixture in solution, one isomer was converted into the other, reaching a diastereomeric excess of up to 94 %. The steric and electronic factors responsible for the epimerization process were investigated by theoretical methods. Cleavage of the η3‐allylpalladium bond by nucleophiles allowed highly substituted chiral butenolides to be synthesized in good enantiomeric excess.
Received November 26, 1998; revised February 23, 1999; accepted May 13, 1999 Gold(III) complexes,... more Received November 26, 1998; revised February 23, 1999; accepted May 13, 1999 Gold(III) complexes, isostructural and isoelectronic with platinum(II) complexes, are of potential interest as antitumor drugs. We prepared four representative square planar gold(III) complexes – AuCl3(Hpm), AuCl2(esal), AuCl(dien)Cl2 and Au(en)2Cl3 – and characterized them both in the solid state and in solution. Thereafter, the cytotoxicity of these compounds was evaluated in vitro against the A2780 human ovarian tumor cell line that was used as the reference cell line. Remarkably, all these gold(III) complexes showed significant cytotoxic effects, AuCl2(esal) showing a potency comparable to cisplatin. The present gold(III) complexes were also tested on the corresponding cisplatin-resistant line and revealed they were able to overcome resistance to cisplatin to a large extent. The implications of these findings for the development of new gold(III) complexes to be tested as antitumor agents are discussed.
The development of new-generation photovoltaic devices through more sustainable production techni... more The development of new-generation photovoltaic devices through more sustainable production techniques and materials is driven by the need to contain the threats to the biosphere while guaranteeing the safety of the supply, accounting for the limited availability of fossil fuels. This study investigates the crystal structure of thin films of chalcogenides, particularly a junction with a p-type (Cu2S) and an n-type (CdS) layer deposited one on top of the other on a Ag(111) substrate, starting from an aqueous solution and by means of electrochemical atomic layer deposition (E-ALD) (the system is denoted by (Cu2S)60/(CdS)60/Ag(111)). The experiment highlights the profound epitaxial relationship existing between the films and the bulk, consequent to the homogenization of the metrics of the CdS and the Cu2S structures to values commensurate to the surface periodicity of the substrate. Cadmium sulfide develops an elementary cell with crystallographic axes parallel to those of the Ag(111) a...
We give an algorithm which goal is to find the energy barrier between a given pair of points in a... more We give an algorithm which goal is to find the energy barrier between a given pair of points in a graph which represents the conformational space of a molecule. If the conformational space is homeomorphic to an -dimensional torus, then the graph can be chosen of a particular form. The UTN software, which implements the algorithm in this case, is described in detail. Finally we focus on applications: to show how UTN works, some examples are carried on in detail, with the additional support of graphical animation1 in the twodimensional case. The source code of the program and some data of the examples are available to the reader.
Several binary metal diphosphinate compounds (ML) have been reported for diphosphinate bonded by ... more Several binary metal diphosphinate compounds (ML) have been reported for diphosphinate bonded by a single methylene fragment. In case of longer bridges, binary products are difficult to isolate in crystalline form. Here, using a solvent assisted mechano-chemistry synthesis, we report two new ML crystalline phases, one hydrated and one anhydrous. The hydrated phase is a 2D coordination polymer with an open framework structure. Its network displays a new topology for coordination polymers and metal organic frameworks. The thermal behavior of the two phases has been studied. Finally, the importance of the bridge length is discussed in view of known metal diphosphinate compounds.
ABSTRACT Reactivity of [Pd(CH3)(CO)(PriDAB)]+[B{3,5-(CF3)2C6H3}4]- (1), where PriDAB = 1,4-diisop... more ABSTRACT Reactivity of [Pd(CH3)(CO)(PriDAB)]+[B{3,5-(CF3)2C6H3}4]- (1), where PriDAB = 1,4-diisopropyl-1,4-diaza-1,3-butadiene, toward alkynes and carbon monoxide was investigated. While the reaction of 1 with phenylacetylene produced stereoregular homopolymer, a stoichiometric insertion of 1-phenyl-1-propyne and 2-butyne into the Pd−acyl bond yielded the palladacycles 2 and 3; subsequent reaction with CO resulted in the formation of novel complexes 4 and 5, which represent the first experimental evidence of a key intermediate in alkyne cyclocarbonylation processes.
We give an algorithm which goal is to find the energy barrier between a given pair of points in a... more We give an algorithm which goal is to find the energy barrier between a given pair of points in a graph which represents the conformational space of a molecule. If the conformational space is homeomorphic to an -dimensional torus, then the graph can be chosen of a particular form. The UTN software, which implements the algorithm in this case, is described in detail. Finally we focus on applications: to show how UTN works, some examples are carried on in detail, with the additional support of graphical animation1 in the twodimensional case. The source code of the program and some data of the examples are available to the reader.
Insertion of 1,2‐disubstituted alkynes into [Pd(CH3)(CO)(BIOX)]+[B{3,5‐(CF3)2C6H3}4]− (1), where ... more Insertion of 1,2‐disubstituted alkynes into [Pd(CH3)(CO)(BIOX)]+[B{3,5‐(CF3)2C6H3}4]− (1), where BIOX=(4S,4′S)‐(−)‐4,4′,5,5′‐tetrahydro‐4,4′‐bis(1‐methylethyl)‐2,2′‐bioxazole, leads to the formation of five‐membered palladacycles, which, by reaction with carbon monoxide, produce a mixture of two diastereomeric forms of a palladium complex containing an η3‐allylic γ‐lactone ligand. On leaving the mixture in solution, one isomer was converted into the other, reaching a diastereomeric excess of up to 94 %. The steric and electronic factors responsible for the epimerization process were investigated by theoretical methods. Cleavage of the η3‐allylpalladium bond by nucleophiles allowed highly substituted chiral butenolides to be synthesized in good enantiomeric excess.
Received November 26, 1998; revised February 23, 1999; accepted May 13, 1999 Gold(III) complexes,... more Received November 26, 1998; revised February 23, 1999; accepted May 13, 1999 Gold(III) complexes, isostructural and isoelectronic with platinum(II) complexes, are of potential interest as antitumor drugs. We prepared four representative square planar gold(III) complexes – AuCl3(Hpm), AuCl2(esal), AuCl(dien)Cl2 and Au(en)2Cl3 – and characterized them both in the solid state and in solution. Thereafter, the cytotoxicity of these compounds was evaluated in vitro against the A2780 human ovarian tumor cell line that was used as the reference cell line. Remarkably, all these gold(III) complexes showed significant cytotoxic effects, AuCl2(esal) showing a potency comparable to cisplatin. The present gold(III) complexes were also tested on the corresponding cisplatin-resistant line and revealed they were able to overcome resistance to cisplatin to a large extent. The implications of these findings for the development of new gold(III) complexes to be tested as antitumor agents are discussed.
The development of new-generation photovoltaic devices through more sustainable production techni... more The development of new-generation photovoltaic devices through more sustainable production techniques and materials is driven by the need to contain the threats to the biosphere while guaranteeing the safety of the supply, accounting for the limited availability of fossil fuels. This study investigates the crystal structure of thin films of chalcogenides, particularly a junction with a p-type (Cu2S) and an n-type (CdS) layer deposited one on top of the other on a Ag(111) substrate, starting from an aqueous solution and by means of electrochemical atomic layer deposition (E-ALD) (the system is denoted by (Cu2S)60/(CdS)60/Ag(111)). The experiment highlights the profound epitaxial relationship existing between the films and the bulk, consequent to the homogenization of the metrics of the CdS and the Cu2S structures to values commensurate to the surface periodicity of the substrate. Cadmium sulfide develops an elementary cell with crystallographic axes parallel to those of the Ag(111) a...
We give an algorithm which goal is to find the energy barrier between a given pair of points in a... more We give an algorithm which goal is to find the energy barrier between a given pair of points in a graph which represents the conformational space of a molecule. If the conformational space is homeomorphic to an -dimensional torus, then the graph can be chosen of a particular form. The UTN software, which implements the algorithm in this case, is described in detail. Finally we focus on applications: to show how UTN works, some examples are carried on in detail, with the additional support of graphical animation1 in the twodimensional case. The source code of the program and some data of the examples are available to the reader.
Several binary metal diphosphinate compounds (ML) have been reported for diphosphinate bonded by ... more Several binary metal diphosphinate compounds (ML) have been reported for diphosphinate bonded by a single methylene fragment. In case of longer bridges, binary products are difficult to isolate in crystalline form. Here, using a solvent assisted mechano-chemistry synthesis, we report two new ML crystalline phases, one hydrated and one anhydrous. The hydrated phase is a 2D coordination polymer with an open framework structure. Its network displays a new topology for coordination polymers and metal organic frameworks. The thermal behavior of the two phases has been studied. Finally, the importance of the bridge length is discussed in view of known metal diphosphinate compounds.
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Papers by Annalisa Guerri