The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

The Discovery of New Crystal Forms of 5-Fluorocytosine Consistent with the Results of Computational Crystal Structure Prediction

A computational search for low-energy crystal structures of 5-fluorocytosine was performed in conjunction with a manual crystallization screen to determine whether solid forms other than the known monohydrate structure could be discovered. The predicted low-energy structures were based on a hydrogen-bonded ribbon, which was observed in two newly determined anhydrous polymorphic crystal structures, a hemipentahydrate, and two solvates, as well as the known monohydrate. An alternative ribbon structure present in some less-stable predicted structures was found in a disordered monohydrate structure. The anhydrous crystal structure prediction was a success, by the criteria of the international crystal structure prediction blind tests. Thus we can rationalize the crystal structure behavior of 5-fluorocytosine as having a strongly preferred two-dimensional ribbon structure, which exhibits versatile methods of packing, leading to polymorphism and a number of closely related solvate structures

A Highly Efficient, Preorganized Macrobicyclic Receptor for Halides Based on CH··· and NH···Anion Interactions

The preorganized, macrobicyclic azaphane (1) exhibits remarkable strong, selective fluoride binding comparable to the most effective bis(tren) cryptands despite binding anions via only three NH groups coupled with three CH hydrogen bond donors. The lower intrinsic affinity of CH donors is compensated by the high degree of preorganization exhibited by azacyclophane 1. Compound 1 is prepared via a tripod−tripod cyclization reaction between 1,3,5-tris-bromomethyl-benzene and an aliphatic tripodal hexatosylated polyamine, followed by the reduction of the resulting bicyclic tosylamine. The crystal structures of the bicyclic tosylamine 2 and four macrobicyclic polyammonium halide salts of 1 are reported. X-ray studies revealed the formation of inclusive 1:1 complexes of 1 with fluoride, chloride, bromide, and iodide. Potentiometric titrations showed very high binding constants for fluoride and chloride with a F-/Cl- selectivity of more than five logarithmic units. The final geometry of the anion cryptates is largely determined by optimization of NH and CH···anion interactions coupled with unfavorable anion−π repulsion for the larger anions

Observation of ³MC Emission in a Mixed 1,10-Phenanthroline Complex of Ruthenium(II) Having a Ru^IIN₆ Core at Room Temperature in Solution

[Ru(1,10-phenanthroline)2(4,4,4‘,4‘-tetramethyl-2,2‘-bisoxazoline)](PF6)2·H2O (1) shows a 3MC emission in CH3CN and CH3OH at room temperature around 590 nm with radiative lifetimes of 1.22 × 10-4 and 1.40 × 10-4 s, respectively. The X-ray crystal structure of 1 has been determined