Chiral Polymer Helices with Shape Identical to Previously Reported Helical Calcium Carbonate Morphologies

Abstract

Helices with highly ordered substructures were found sporadically during precipitation of self‐assembled silica‐barium carbonate “biomorphs”. Identical morphologies are already known and cited in the literature as helical calcite structures, formed by the influence of chiral phosphoserine copolypeptides. Yamamoto et al. claim that the handedness of the helices can be tuned by the chirality of the amino acids in the phosphoserine copolypeptides. Optical and scanning electron microscopy, energy‐dispersive X‐ray analysis, thermogravimetry, as well as proton and carbon nuclear magnetic resonance were performed on selected twisted ribbons, proving that these helical superstructures—in shape identical to the helical calcite morphologies reported by Yamamoto et al.—do not consist of inorganic material but of an organic polymer, representing plastic abrasion caused by scratching glass pipettes along plastic surfaces.magnified image

Reversible Twisting during Helical Hippuric Acid Crystal Growth

“…12 Further confounding is that some microscale helices, supposedly composed of barium carbonate, were devoid of inorganic matter; they were instead a consequence of the abrasion of polystyrene containers. 13 Helical ribbons of molecular crystals such as decacylene 14 or 10,12-tricosadynoic anhydride 15 can be easily grown from solution, but the optical analyses of helical precession are complicated by the presentation of steep angles of incidence and extreme fragility. We set out to establish conditions for the in situ optical analysis of a simple, helical crystal.…”

“…Helical crystals are displayed abundantly in the high molecular weight polymer literature, but the mechanisms of crystal deformation have been subject to vigorous debate . Further confounding is that some microscale helices, supposedly composed of barium carbonate, were devoid of inorganic matter; they were instead a consequence of the abrasion of polystyrene containers . Helical ribbons of molecular crystals such as decacylene or 10,12-tricosadynoic anhydride can be easily grown from solution, but the optical analyses of helical precession are complicated by the presentation of steep angles of incidence and extreme fragility.…”

Wachstumsinduziertes Biegen und Verwinden von Einkristallen

“…[278,279] Allerdings zeigten Kunz und Mitarbeiter, dass die mit SEM beobachteten Calcit-Helices [278,279] stark an die allgegenwärtigen Abschabungen von Kunststoff-Laborausrüstung erinnern, was die Notwendigkeit unterstreicht, repräsentative mikroskopische Aufnahmen zu zeigen und nicht nur die außergewçhnlichste Form aus einer Sammlung. [280]…”

Controlling Mesoscale Crystal Helicity with Additives, Again

“…However, if redundant claims are generated, then it becomes urgent not only to turn our collective attention to the ostensible pioneers but to establish the veracity of their work. Recently, researchers claimed to control mesoscale twisting of crystallites induced by chiral additives. − In fact, in 1907, Wallerant reported resorcinol crystals from the melt as mesoscale helical fibers, twisting right or left depending on the configuration of chiral additives . How and why he achieved this control more than 100 years ago and its justification on the basis of contemporary techniques in computational crystallography are communicated herein because the relationship between molecular and mesoscale chirality has reemerged in the past three decades as a subject of research at the forefront of materials chirality…”

“…Wallerant used this procedure, known as “sensing the screw”. Others used it more recently to characterize banded spherulites of high polymers and small molecules. , Addition of 6–23 wt % T d produced left-handed helices in R β and right-handed helices for R γ . Naturally, T l had the opposite effect on the helix handedness.…”