Ecstasy: 3,4-Methylenedioxymethamphetamine (MDMA)

This is the published version. Copyright 1998 International Union of CrystallographyThe crystal structure of 3,4-methylenedioxymethamphetamine {systematic name: N-methyl-l-[3,4-(methylenedioxy) phenyl]-2-aminopropane } hydrochloride, C 11H 15 - NO2.HC1, also known as 'ecstasy' or MDMA, has been determined by X-ray diffraction

Dichroism in helicoidal crystals

Accounting for the interactions of light with heterogeneous, anisotropic, absorbing, optically active media is part of the characterization of complex, transparent materials. Stained biological structures in thin tissue sections share many of these features, but systematic optical analyses beyond the employ of the simple petrographic microscopes have not be established. Here, this accounting is made for polycrystalline, spherulitic bundles of twisted d-mannitol lamellae grown from melts containing light-absorbing molecules. It has long been known that a significant percentage of molecular crystals readily grow as helicoidal ribbons with mesoscale pitches, but a general appreciation of the commonality of these non-classical crystal forms has been lost. Helicoidal crystal twisting was typically assayed by analyzing refractivity modulation in the petrographic microscope. However, by growing twisted crystals from melts in the presence of dissolved, light-absorbing molecules, crystal twisting can be assayed by analyzing the dichroism, both linear and circular. The term "helicoidal dichroism" is used here to describe the optical consequences of anisotropic absorbers precessing around radii of twisted crystalline fibrils or lamellae. d-Mannitol twists in two polymorphic forms, α and δ. The two polymorphs, when grown from supercooled melts in the presence of a variety of histochemical stains and textile dyes, are strongly dichroic in linearly polarized white light. The bis-azo dye Chicago sky blue is modeled because it is most absorbing when parallel and perpendicular to the radial axes in the respective spherulitic polymorphs. Optical properties were measured using Mueller matrix imaging polarimetry and simulated by taking into account the microstructure of the lamellae. The optical analysis of the dyed, patterned polycrystals clarifies aspects of the mesostructure that can be difficult to extract from bundles of tightly packed fibrils

Relation between 2D/3D chirality and the appearence of chiroptical effects in real nanostructures.

The optical activity of fabricated metallic nanostructures is investigated by complete polarimetry. While lattices decorated with nanoscale gammadia etched in thin metallic films have been described as two dimensional, planar nanostructures, they are better described as quasi-planar structures with some three dimensional character. We find that the optical activity of these structures arises not only from the dissymmetric backing by a substrate but, more importantly, from the selective rounding of the nanostructure edges. A true chiroptical response in the far-field is only allowed when the gammadia contain these non-planar features. This is demonstrated by polarimetric measurements in conjunction with electrodynamical simulations based on the discrete dipole approximation that consider non-ideal gammadia. It is also shown that subtle planar dissymmetries in gammadia are sufficient to generate asymmetric transmission of circular polarized light

Chiroptical Studies on Anisotropic Condensed Matter: Principle and Recent Applications of the Generalized-High Accuracy Universal Polarimeter

Chiroptics is the study of the changes in circular polarization states of light transmitted through analytes typically dissolved in isotropic solutions. However, experimental challenges have long prevented chiroptical measurements of anisotropic media such as single crystals of low symmetry, liquid crystals, or structured films. The high accuracy universal polarimeter (HAUP) was introduced in 1983 to investigate the differential refraction of left and right circular polarization states, circular birefringence (CB), and even in anisotropic media that are dominated by the differential refraction of orthogonal linear polarization states, linear birefringence (LB). In this century, the HAUP was extended to also measure not only the dispersive optical effects (CB and LB) but also the corresponding dissipative effects, circular dichroism (CD) and linear dichroism (LD), differences in light absorption. The improved device is the generalized-HAUP (G-HAUP). Not only can it deliver all the linear optical properties of dissymmetric, anisotropic, and absorbing media, but it can also do so in the ultraviolet as well as the visible part of the electromagnetic spectrum. In this review, characteristic features of the G-HAUP and its applications to crystals of photomechanical salicylidenephenylethylamines, alanine, benzil, and magneto-optical CeF3 are described

Resorcinol crystallization from the melt: a new ambient phase and new “riddles”

Structures of the alpha and beta phases of resorcinol, a major commodity chemical in the pharmaceutical, agrichemical, and polymer industries, were the first polymorphic pair of molecular crystals solved by X-ray analysis. It was recently stated that "no additional phases can be found under atmospheric conditions" (Druzbicki, K. et al. J. Phys. Chem. B 2015, 119, 1681.). Herein, is described the growth and structure of a new ambient pressure phase, epsilon, through a combination of optical and X-ray crystallography evaluated by computational crystal structure prediction algorithms. alpha-Resorcinol has long been a model for mechanistic crystal growth studies from solution and the vapor because prisms extended along the polar axis grow much faster in one direction than in the opposite direction. Research has focused on identifying the absolute sense of the fast direction – the so-called ‘resorcinol riddle’ – with the aim of identifying how solvent controls crystal growth. Here, the growth velocity dissymmetry in the melt is analyzed for the ? phase. The epsilon phase only grows from the melt, concomitant with the beta phase, as polycrystalline, radially growing spherulites. If the radii are polar, the sense of the polar axis is an essential feature of the form. Here, this determination is made for spherulites of beta resorcinol (epsilon, point symmetry 222, does not have a polar axis) with additives that stereoselectively modify growth velocities. Both beta and epsilon have the additional feature that individual radial lamellae may adopt helicoidal morphologies. We correlate the appearance of twisting in beta and epsilon with the symmetry of twist-inducing additives

Gender and Library of Mineralogy

Few would expect women to feature often in the literature on minerology from the 15th through the 19th centuries, the recorded history of science being what it is. Among the approximately 1500 scholars in a massive catalogue of authors of mineralogy texts from 1439 to 1919 complied by the independent scholar, Curtis P. Schuh, we count six women as primary entries and three others discussed secondarily. From the documents that Schuh left behind before his death, our database for this investigation, women wrote approximately 0.5% of the texts described. Only very unusual circumstances supported the life of a woman devoted to crystals in centuries past