The molecules at the surface of a liquid have different organization and dynamics from those in bulk, potentially altering rate crystal nucleation polymorphic selection, but this effect remains poorly understood. Here we demonstrate that pure liquid, d-arabitol, is vastly enhanced, by 12 orders magnitude, selects polymorph. intensifies with cooling can be inhibited dilute, surface-active second component. This phenomenon arises anisotropic molecular packing interface its similarity to...

As a result of its higher molecular mobility, the surface an amorphous drug can grow crystals much more rapidly than bulk, causing poor stability and slow dissolution products. We show that nanocoating chitosan (a pharmaceutically acceptable polymer) be deposited on indomethacin by electrostatic deposition, leading to significant improvement physical stability, wetting aqueous media, rate, powder flow, tabletability. The coating condition was chosen so positively charged polymer deposits...

Reversible solid-state transformations are important in stimuli-responsive materials. The current understanding is limited on what kind of structure enables reversible transitions. We report that for molecular solids containing nitro groups, phase transitions can occur if the group a hydrogen bond (HB) acceptor and has torsional freedom. use polymorphs nifedipine (NIF) to illustrate this phenomenon taking advantage their different packing but identical chemical structure. NIF six known with...

An amorphous drug–polymer salt (ADPS) can be remarkably stable against crystallization at high temperature and humidity (e.g., 40°C/75% RH) provide fast release. Here, we report that process conditions strongly influence the degree of proton transfer (salt formation) between a drug polymer in turn product's stability For lumefantrine (LMF) formulated with poly(acrylic acid) (PAA), first show materials prepared by slurry conversion antisolvent precipitation produce single trend which...

Vapor-deposited glass mixtures of organic semiconductors commonly serve as active layers in electronic devices, whose lifetime and performance are strongly influenced by the stability structure these mixed glasses. Here, we study anisotropic molecular packing six codeposited semiconductor with a 50:50 weight ratio differential scanning calorimetry spectroscopic ellipsometry. We find that all binary systems exhibit high kinetic significantly reduced enthalpy relative to corresponding...

X-ray scattering of liquid 2-ethyl-1-hexanol (2E1H) has been measured from its state to glassy with focus on the main peak and prepeak. The peak, associated packing alkyl chains, shifts higher angle sharpens in a manner consistent closely packed spheres, until kinetic arrest at glass transition temperature Tg (146 K). In contrast, prepeak, correlation hydroxyl groups separated by hydrocarbon shows near 220 K, below which width is nearly frozen insensitive passage Tg. This coincides similar...

Surfactants are commonly incorporated into amorphous formulations to improve the wetting and dissolution of hydrophobic drugs. Using X-ray photoelectron spectroscopy, we find that a surfactant can significantly enrich at surface an drug, up 100% coverage, wihout phase separation in bulk. We compared four different surfactants (Span 80, Span 20, Tween 20) same host acetaminophen 80 hosts (acetaminophen, lumefantrine, posaconazole, itraconazole). For each system, bulk concentrations were 0, 1,...

While previous work has identified the conditions for preparing ultrastable single-component organic glasses by physical vapor deposition (PVD), little is known about stability of codeposited mixtures. Here, we prepared binary PVD semiconductors, TPD (N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine) and m-MTDATA (4,4′,4″-Tris[phenyl(m-tolyl)amino]triphenylamine), with a 50:50 mass concentration over wide range substrate temperatures (Tsub). The enthalpy kinetic are evaluated differential...

Physical vapor deposition can be used to prepare highly stable organic glass systems where the molecules show orientational and translational ordering at nanoscale. We have low-dose four-dimensional scanning transmission electron microscopy (4D STEM), enabled by a fast direct detector, map columnar order in glassy samples of discotic mesogen using 2 nm probe. Both vapor-deposited liquid-cooled films domains similar orientation, but their size varies from tens hundreds nanometers, depending...

Recent work has shown that an amorphous drug-polymer salt can be highly stable against crystallization under hot and humid storage conditions (e.g., 40 °C/75% RH) provide fast release these advantages depend on the degree of formation. Here, we investigate formation between basic drug lumefantrine (LMF) several acidic polymers: poly(acrylic acid) (PAA), hypromellose phthalate (HPMCP), acetate succinate (HPMCAS), cellulose (CAP), Eudragit L100, L100-55. Salt was performed by "slurry...

First demonstrated by Pasteur, chiral separation crystallization is perhaps the simplest method to resolve a racemic mixture into pure enantiomers, but considered inapplicable most compounds (90–95%) due their spontaneous as compound where opposite enantiomers coinhabit unit cell. Here, we demonstrate that can occur seeding in system (neat arabitol melt) otherwise crystallizes compound. The approach helps extend systems were previously thought impossible.

We aim to understand the potential impact of a modest chemical modification drug molecule on downstream design its amorphous solid dispersion (ASD) formulation. To this end, we used sorafenib (SOR) and fluorinated form, regorafenib (REG), as model drugs, assess single hydrogen substitution by fluorine molecular interaction miscibility between PVP or PVP–VA, two commonly polymers for ASDs. In study, observed that Tg values PVP–VA based ASDs SOR deviated positively from Gordon–Taylor...

Liquid crystals (LCs) undergo fast phase transitions, almost without hysteresis, leading to the notion that it is difficult bypass LC transitions. However, recent work on itraconazole has shown a nematic-to-smectic transition can be frustrated or avoided at moderate cooling rates. At each rate, highest smectic order obtained determined by kinetic arrest of end-over-end molecular rotation. We report same phenomenon occurs in system saperconazole, an analog where two Cl atoms replaced F....

An impurity usually degrades the crystalline order of host material. Here, we investigate an intriguing counterexample where strongly enhances ordering a thermotropic liquid crystal while increasing its fluidity. At 5 wt %, glycerol smectic layering hydrophobic itraconazole by reducing random molecular offsets in each layer, creating more compact layers with nearly zero thermal expansion. We attribute glycerol's effect to cross-linking hydrogen bonds within monolayer. This system suggests...

Amorphous solid dispersions (ASDs) can be used to enhance the solubility and bioavailability of poorly soluble drugs. An ASD is often a ternary system containing drug, surfactant, polymer. Recent work on binary ASDs has observed significant differences between surface bulk compositions, with impacts wettability stability. Here we investigate composed antifungal posaconazole, surfactant Span 80, dispersion polymer (PVP or PVP/VA). The loading was fixed at typical level 5 wt %, drug/polymer...

X-ray scattering has been used to characterize glassy itraconazole (ITZ) prepared by cooling at different rates. Faster produces ITZ glasses with lower (or zero) smectic order more sinusoidal density modulation, larger molecular spacing, and shorter lateral correlation between the rod-like molecules. We find that each glass is characterized not one, but two fictive temperatures Tf (the temperature which a chosen parameter frozen in equilibrium liquid). The higher associated regularity of...

An amorphous material can have vastly higher mobility on the surface than in bulk and, as a result, shows fast crystallization. Most materials contain multiple components, but effect of composition dynamics remains poorly understood. In this study, indomethacin was measured using method surface-grating decay presence moisture and surfactant Tween 20. It is found that both components significantly enhance mobility, their effects are well described by principle concentration–temperature...

X-ray photoelectron spectroscopy has been used to measure the surface concentration and enrichment kinetics of a polymer in glass-forming molecular liquid. As model, bulk-miscible system maltitol-polyvinylpyrrolidone (PVP) was studied. The PVP is significantly higher at liquid/vapor interface than bulk by up factor 170, effect increases with its weight. At freshly created interface, gradually from value rate controlled diffusion. diffusion coefficient obtained agrees that calculated...

Highly ordered liquid crystalline (LC) phases have important potential for organic electronics. We studied the molecular alignment and domain structure in a columnar LC thin film with nanometer resolution during situ heating using four-dimensional scanning transmission electron microscopy (4D STEM). The initial disordered vapor-deposited glass rapidly at its transition temperature into hexagonal phase small (<10 nm), well-aligned, planar domains (columns oriented parallel to surface). Upon...

X-ray scattering has been used to characterize the columnar packing and π stacking in a glass-forming discotic liquid crystal. In equilibrium state, intensities of peaks for are proportional each other, indicating concurrent development two orders. Upon cooling into glassy π-π distance shows kinetic arrest with change thermal expansion coefficient (TEC) from 321 109 ppm/K, while intercolumnar spacing exhibits constant TEC 113 ppm/K. By changing rate, it is possible prepare glasses wide range...

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Physical vapor deposition can be used to prepare highly stable organic glass systems where the molecules show orientational and translational ordering at nanoscale. We have low-dose four-dimensional scanning transmission electron microscopy (4D STEM), enabled by a fast direct detector, map columnar order in glassy samples of discotic mesogen using 2 nm probe. Both deposited liquid cooled films domains similar orientation, but their size varies from tens hundreds nanometers, depending on...