The crystal and molecular structure of chandonium dibromide: A synthetic bisquaternary aza steroidal neuromuscular blocking agent

The crystal and molecular structure of 17a-methyl-3-pyrrolidino-17a-aza-D-homo-5-androstene dimethyl bromide (HS818, chandonium dibromide). C₂₆H₄₆N₂Br₂, has been determined crystallographically by the heavy atom method and refined by full-matrix least-squares calculations toR =0.074 for 5045 reflections. The compound crystallizes in space groupP2₁2₁2₁ witha=6.468(2),b=14.055(5),c=28.216(11) Å. The N⁺...N⁺ inter-onium distance in chandonium bromide is 10.32 Å, close to the distance of 10.29 Å observed in chandonium iodide. Rings A, C, and D have a chair conformation and ring B is in a half-chair conformation. Ring E has a distorted envelope conformation. All rings in the steroid skeleton aretrans-connected.     

Steroids and related studies. Part LIV. The crystal and molecular structure of 17aβ-(2-hydroxyethyl)-3β-pyrrolidino-17a-aza-d-homo-5-androstene dimethiodide (hs-626)

The crystal structure of the potent synthetic aza steroidal neuromuscular blocking agent 17a-(2-hydroxyethyl)-3-pyrrolidino-17a-aza-D-homo-5-androstene dimethiodide (HS-626), (C₂₇H₄₈N₂O)²⁺2I^–, has been determined by the heavy-atom method and refined by block diagonal least squares toR _o =0.044 for 3041 observed reflections andR=0.072 for 4313 reflections measured on a four-circle diffractometer in the /2 scanning mode, employing Nb-filtered MoK radiation. The crystals are orthorhombic,P2₁2₁2₁,a=14.671(2),b=17.594(3),c=10.908(2) Å,Z=4. RingsA, C, andD-homo have chair conformations, ringB is a half-chair, and the pyrrolidine ringE has an envelope conformation. The N⁺---N⁺ distance of 10.33 Å is within the usual range associated with potent neuromuscular blocking. The hydroxyethyl side group appended to N⁺ (17a) forms part of an acetylcholine-like moiety which is observed to adopt thet,-g conformation commonly found in acetylcholine. This feature probably accounts for the dramatic increase in potency of HS-626 compared to similar drugs lacking this feature. Potential-energy calculations for the free HS-626 molecule indicate that the side chain may adopt a variety of conformations in the ranget, (⁺ g to^– g).     

Steroids and related studies. Part 60. Crystal and molecular structures of 17β-(2-hydroxyethyl)-3β-and 3α-pyrrolidino-17a-aza-D-homo-5-androstenes: HS-625 form 1, (3β-pyrrolidino) and HS-625 form 2 (mixed-3α and -3β-pyrrolidino epimers)

The crystal structures of two forms of 17-(2-hydroxyethyl)-3-pyrrolidino-17a-aza-D-homo-5-androstene (HS-625) are reported. In HS-625 (aqueous solvate) form 1, moleculeA, and HS-625 (anhydride) form 2, moleculeB, the pyrrolidine group is 3- substituted, while in HS-625 (anhydride) form 2, moleculeC has its pyrrolidine ring -substituted. HS-625 form 1 is orthorhombic, space groupP2₁2₁2₁, witha=7.089(4),b=11.502(6),c=28.975(16) Å,Z=4; form 2 is triclinic, space groupP1, witha=14.013(8),b=12.572(6),c=6.688(4) Å, =95.187(20), =103.491(21); =86.210(20)°,Z=2. MoleculesA andB have similar geometry, differences in moleculeC being related to strain caused by the unusual 3- ring substituent which also produces a pronounced kink in the backbone of the molecule. An unusual feature of the analysis of form 1 is the location of the water hydrogens in the difference electron density well above background. None of the OH hydrogens was located. Both structures are hydrogen bonded, but the pyrrolidine nitrogen N(31) in moleculeC is heavily congested and is unable to act as an acceptor. The hydroxyethyl side chain, important for activity, has a different conformation in the three molecules (t,g, t,-g, andt,t respectively).     

Structure of a potent neuromuscular blocking agent: Caracurine-II dimethochloride octahydrate, [C40H44N4O2]2+·2CI−·8H2O

Crystals of this calabash curare alkaloid, space groupP2₁; havea=12.695(4), Å,b=7.424(2) Å,c=21.762(6) Å,=98.03(5)°,Z=2,F(000)=884. The structure was solved by direct methods and refined by least squares toR=0.10. The alkaloid cation, with two-fold molecular symmetry, has a highly fused ring system and is structurally rigid. This determination provides accurate stereochemical parameters for those atoms and groups (N⁺ centers, aromatic rings, and hydrogen bond acceptors) postulated by various theories as involved in binding to the acetylcholine receptor. In the crystal, layers of alkaloid cations parallel to thebc plane alternate with layers containing two Cl^– ions and eight water molecules distributed almost randomly over ten sites. Electrostatic attractions between N⁺ and Cl^– bind the alternating layers together. Each one of the ten sites is, on average, 4.60 Å from one or two N⁺, allowing the two Cl_– ions to be disordered. Binding interactions within the alkaloid layers are solely van der Waals attractions. Within each H²O/C1^– layer there is a complex hydrogen bond system, including four infinite spirals parallel to theb axis, with an average bonding distance of 2.94 Å. There are no hydrogen bonds between layers. The possible relevance to the activity of the alkaloid of its ability to organize large amounts of water is discussed.     

Structure of potassium germanophosphate glasses by X-ray and neutron diffraction. Part 1: Short-range order

It has been reported that the addition of K₂O or P₂O₅ to binary germanate glasses increases the Ge−O coordination numbers (N_GeO). The present work describes X-ray and neutron diffraction studies aimed at clarifying the concomitant effects of both oxides on the structures of ternary K₂O-GeO₂-P₂O₅ glasses. The Ge−O coordination numbers obtained range from 4.2 to 5.1, less than what is predicted according to a model which assumes all oxygen atoms form network bridges similar to those found in the related crystal structures. This implies that the glass structures must include terminal oxygen sites, likely associated with the PO₄ tetrahedra, that are neutralized by coordinating K⁺ ions. The shapes of the high resolution first-neighbor diffraction peaks do not indicate distinctly different species of P−O and Ge−O bonds. The model for the increase of N_GeO which is based on an increase of the fraction of GeO₆ units, at the expense of GeO₄ units, is supported by the analysis of the two main components of the Ge−O peak used in the fits. However, the existence of a GeO₅ fraction cannot be excluded from the present data sets. A linear relation between the total Ge−O coordination numbers and mean Ge−O distances exists, assuming end members of units GeO₄ and GeO₆ with bond lengths of ∼0.175 and ∼0.190 nm, respectively.     

Steroids and related studies,part 66: Crystal and molecular structure of 17a-(2-acetoxyethyl)-17a-aza-d-homo-5-androsten-3β-yl-acetate methiodide (HS465), a monoquaternary azasteroid incorporating an acetylcholine-like moiety

The crystal stucture of a synthetic monoquaternary azasteroid containig an acetylcholine-like moiety, 17a-(2-acetoxyethyl)-17a-aza-d-homo-5 androsten-3-yl-acetate methiodide (HS465) (C₂₆H₄₂NO₄)⁺I^–, has been determined by the heavy-atom method and refined by full-matrix least squares toR=0.0410 for 2462 reflections, using MoK radiation (=0.7114 Å). The crystals are monoclinic:P2₁,a=15.244(4),b=9.009(6),c=9.886(3) Å,=104.26°(3),Z=2. RingsA andC have distorted-chair conformations, ring d-homo is a symmetrical chair, and ringB is a half-chair. The acetoxyethyl side-group appended to N(17a) simulates an acetylcholine-like moiety, and exhibits a conformation similar to that frequently adopted by acetylcholine itself in the presence of heavy anions.     

Lattice dynamics and related properties of AIBIII and AIIBIV compounds,I. Elastic constants

The present state of knowledge of the elastic properties of the ternary chalcopyrite compounds and some related materials is reviewed. Results of experimental elastic constant determinations are critically evaluated by comparing with other experimentally available material parameters that directly depend on the elastic constants. Possible reasons for existing discrepancies and obvious inconsistencies in the experimental data are discussed. The results of theoretical calculations of the elastic constants of these compounds based on different theoretical models and approaches are compared with experimental data and are assessed concerning achievable accuracy and reliability. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

TMTSF2X Salts. Preparation,Structure and Effect of the Anions

The preparation of the TMTSF molecule and some of its properties are reviewed. The preparation of metallic and superconducting TMTSF X salts is described and some structural aspects are discussed, with emphasis of possible order-disorder transitions when X is a non-centrosymmetric anion. Preliminary results for TMTSF₂ TeF₅ which remain conducting to at least 5 K are presented.     

The role of X-ray crystallography in drug design: Identification of the two isomers 17β-hydroxy-17α-methyl-5(β andα)-androstano-(2,3-C)-1′, 2′, 5′-oxadiazole (HS804 and HS805) (steroids and related studies,Part 62)

Crystal structure analysis has distinguished between the two epimers 17-hydroxy-17-methyl-5( and)-androstano-(2, 3-C)-1, 2, 5-oxadiazole (HS804 and HS805). HS804 is trigonal,P3₂,a=14.820(4),c=7.177(3) Å,Z=3 and HS805 is orthorhombic,P2₁2₁2₁,a=9.507(4),b=18.528,c=10.048(4) Å,Z=4. The crystal structures were solved by direct methods and refined by full-matrix least squares toR=0.0376 for 1419 reflections (HS804) andR=for 1819 reflections (HS805), using diffractometer measured data with CuK radiation. The two molecules have different ring connections,A/B cis in HS804 andA/B trans in HS805, the planar oxadiazole ring beingcis fused to ringA in both molecules. RingA is strained in both molecules.     

Comment on: “Growth,optical, photoluminescence,dielectric, second and third order nonlinear optical studies of benzoyl valine acentric crystal” [(2017) Mol. Cryst. Liq. Cryst., 658, 186–197]

Abstract

In a recent paper [(2017) Mol. Cryst. Liq. Cryst., 658, 186–197], Kumari et al. studied the optical, photoluminescence and dielectric properties of the benzoyl valine acentric crystal. The refractive index of the samples is calculated based on the reflectance spectra and obtained values were used to calculate other optical parameters such as the electric susceptibility, optical and electrical conductivity. It is shown in this comment that the authors have used a wrong approach to calculate the reflectance spectra of the samples and consequently, the mentioned optical parameters are incorrect.     

Complexation with diol host compounds. Part 3. Molecular inclusion of 4-methylcyclohexanone and 2-methylcyclohexanone by the host,trans-9,10-dihydroxy-9,10-diphenyl-9,10-dihydroanthracene

The structures of the 12 molecular complexes oftrans-9,10-dihydroxy-9,10-diphenyl-9,10-dihydroanthracene with 4-methylcyclohexanone (1) and with 2-methylcyclohexanone (2) have been determined by X-ray crystallography. The crystal data are as follows: Compound (1):P2₂/c,a=8.838(2) Å,b=8.92(1) Å,c=20.879(8)=Å,=98.67(2)°,V=1627(2) ų,Z=2 andR=0.062 for 2201 unique MoK reflections; Compound (2):P¯1,a=8.917(3) Å,b=9.900(2) Å,c=11.250(4) Å,a=68.72(2)°,=64.39(3)°, =74.86(2)°,V=828.1(5) ų,Z=1 andR=0.098 for 2563 unique reflections. Both inclusion compounds exhibit O-HO=C hydrogen bonding interactions. The thermal properties of these compounds have been characterized by DTA and TGA thermograms.