Van der Waals interactions in the self-assembly of 5-amino[6]helicene on Cu(100) and Au(111)

A combination of Scanning Tunnelling Microscopy and Density Functional Theory simulations highlights the role of van der Waals interactions in the self-assembly of an aminohelicene on Cu(100) and Au(111).Fil: Ascolani, Hugo del Lujan. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (centro Atómico Bariloche); ArgentinaFil: Van Der Meijden, Maarten W.. Syncom BV; Países BajosFil: Cristina, Lucila Josefina. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (centro Atómico Bariloche); ArgentinaFil: Gayone, Julio Esteban. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (centro Atómico Bariloche); ArgentinaFil: Kellogg, Richard M.. Syncom BV; Países BajosFil: Fuhr, Javier Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (centro Atómico Bariloche); ArgentinaFil: Lingenfelder, Magalí. Max Planck-EPFL Laboratory for Molecular Nanoscience; Suiz

Resolution of Omeprazole Using Coupled Preferential Crystallization: Efficient Separation of a Nonracemizable Conglomerate Salt under Near-Equilibrium Conditions

A facile and efficient resolution of omeprazole as the monopotassium salt diethanol solvate using coupled preferential crystallization has been developed. This approach uses small perturbations in solution-phase concentration to control the competing process of selective crystal growth while suppressing unwanted primary nucleation. The result is a selective crystallization technique that replaces the traditional batch-type isolation with a continuous process amenable to scale, which provides easy access to enantiopure conglomerate crystals

Resolution of Omeprazole Using Coupled Preferential Crystallization: Efficient Separation of a Nonracemizable Conglomerate Salt under Near-Equilibrium Conditions

A facile and efficient resolution of omeprazole as the monopotassium salt diethanol solvate using coupled preferential crystallization has been developed. This approach uses small perturbations in solution-phase concentration to control the competing process of selective crystal growth while suppressing unwanted primary nucleation. The result is a selective crystallization technique that replaces the traditional batch-type isolation with a continuous process amenable to scale, which provides easy access to enantiopure conglomerate crystals

Synthesis, Properties, and Two-Dimensional Adsorption Characteristics of [6]Hexahelicene-7-carboxylic acid

A convergent synthesis of racemic [6]hexahelicene- 7-carboxylic acid by cross-coupling of a bicyclic and a tricyclic component is described. A metal-catalyzed ringclosure is also a fundamental component of the synthetic approach. Scanning tunneling microscopy (STM) measurements of the racemate self-assembled on Au(111) at liquid–solid interface revealed the formation of ordered racemic 2D crystals.status: publishe

A Chiral Self-Assembled Monolayer Derived from a Resolving Agent and its Performance as a Crystallization Template for an Organic Compound from Organic Solvents

A new chiral nonracemic thiol derived from a popular acidic resolving agent that incorporates a cyclic disubstituted phosphate group (phencyphos) has been prepared in enantiomerically pure form. The stereochemistry and absolute configuration were established by performing a single-crystal X-ray structural analysis of a synthetic intermediate. The thiol compound was used for the preparation of self-assembled monolayers (SAMs) on both monocrystalline and polycrystalline metallic gold, which have very different surface roughness. The monolayers were used to promote the nucleation and growth of crystals from nonaqueous solutions of an organic molecule (the parent phencyphos) of similar structure to the compound present in the monolayer. The template layers influence the nucleation and growth of the phencyphos crystals despite the lack of two-dimensional order in the surfaces. Heterogeneous nucleation of phencyphos takes place upon evaporation of either CHCl3 or isopropanol solutions of the compound on the SAM surfaces, where the evaporation rate merely influences the size and homogeneity of the crystals. The roughness of the surface also plays an important role; the polycrystalline gold produces more homogeneous samples because of the greater number of nucleation sites. Clear evidence for nucleation and growth on the surfaces is shown by scanning electron microscopy. The variation in crystal form achieved by using different surfaces and solvents suggests that the layers are applicable for the preparation of organic crystals from organic solutions.

Self-assembly of an asymmetrically functionalized [6]helicene at liquid/solid interfaces

STM brings to light chirality aspects of the self-assembly of a functionalized helicene at the interface between a liquid and the solid substrates, gold and graphite. This reveals conditions for conglomerate formation.status: publishe

Resolution of Omeprazole Using Coupled Preferential Crystallization: Efficient Separation of a Nonracemizable Conglomerate Salt under Near-Equilibrium Conditions

A facile and efficient resolution of omeprazole as the monopotassium salt diethanol solvate using coupled preferential crystallization has been developed. This approach uses small perturbations in solution-phase concentration to control the competing process of selective crystal growth while suppressing unwanted primary nucleation. The result is a selective crystallization technique that replaces the traditional batch-type isolation with a continuous process amenable to scale, which provides easy access to enantiopure conglomerate crystals

Chiral expression of adsorbed (MP) 5-amino[6]helicenes: from random structures to dense racemic crystals by surface alloying

The chiral expression of a molecule on a surface is driven from a random solid solution on Cu(100) to a racemic crystal on a Sn/Cu(100) alloy. Density functional theory simulations reveal how the growth of the racemate is influenced by the underlying surfaceFil: Fuhr, Javier Daniel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Van der Meijden, Maarten W,. Syncom Bv; Países BajosFil: Cristina, Lucila Josefina. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Física de Metales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; ArgentinaFil: Rodriguez, Luis Miguel. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Kellogg, Richard M.. Syncom Bv; Países BajosFil: Gayone, Julio Esteban. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Ascolani, Hugo. Comisión Nacional de Energía Atómica. Gerencia del Area de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); ArgentinaFil: Lingenfelder, Magalí Alejandra. Max Planck-epfl Laboratory For Molecular Nanoscience; Suiz

Synthesis, Properties, and Two-Dimensional Adsorption Characteristics of 5-Amino[6]hexahelicene

A convergent synthesis of racemic 5-amino[6]hexahelicene is described. Cross-coupling reactions are used to assemble a pentacyclic framework, and a metal-catalyzed ring-closure comprises the final step. The enantiomers were separated by means of chromatography and the absolute configurations were assigned by comparison of the CD spectra with hexahelicene. The t1/2 value for racemization at 210 °C was approximately 1 hour. Scanning tunneling microscopy (STM) measurements were carried out on enantiopure and racemic samples of aminohelicene on Au(111) under ultrahigh vacuum (UHV) conditions. Stairway to heaven? In a convergent synthesis of racemic 5-amino[6]hexahelicene (see figure), cross-coupling reactions assemble a pentacyclic framework, with a metal-catalyzed ring closure as the final step. The enantiomers are separated by means of chromatography and the absolute configurations assigned by comparison of the CD spectra with hexahelicene. Furthermore, scanning tunneling microscopy (STM) on Au(111) was performed under ultrahigh vacuum.Fil: Van Der Meijden, Maarten W.. No especifíca;Fil: Gelens, Edith. No especifíca;Fil: Murillo Quiros, Natalia Maria. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Fuhr, Javier Daniel. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Gayone, Julio Esteban. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Ascolani, Hugo del Lujan. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Wurst, Klaus. Universidad de Innsbruck; AustriaFil: Lingenfelder, Magalí Alejandra. Ecole Polytechnique Federale de Lausanne. Max Planck-epfl Center For Molecularnanosciencie And Technology; FranciaFil: Kellogg, Richard M.. No especifíca

Resolution of Omeprazole Using Coupled Preferential Crystallization: Efficient Separation of a Nonracemizable Conglomerate Salt under Near-Equilibrium Conditions

A facile and efficient resolution of omeprazole as the monopotassium salt diethanol solvate using coupled preferential crystallization has been developed. This approach uses small perturbations in solution-phase concentration to control the competing process of selective crystal growth while suppressing unwanted primary nucleation. The result is a selective crystallization technique that replaces the traditional batch-type isolation with a continuous process amenable to scale, which provides easy access to enantiopure conglomerate crystals