Interface induced crystal structures of dioctyl-terthiophene thin films

The Role of Structural Factors in Support-Seeking Among Women Experiencing Intimate Partner Violence (IPV) in Mwanza, Tanzania: Findings From a Qualitative Study

In this qualitative study of women participating in an intimate partner violence (IPV) prevention trial, experiences of IPV and the context that shapes support-seeking were explored through in-depth interviews and focus groups discussions. Decisions to seek support were influenced by a range of factors including fear of further abuse, shame, acceptance of IPV as normal, belief that IPV is a private matter between the couple, economic dependence on male partners, and a poorly responsive legal and justice system. Gender empowerment programs need to intervene at the social, cultural, political, and economic levels that shape justification and meanings attached to IPV and women's decisions in seeking support.

Sexual and Reproductive Health and Reproductive Coercion in Women Victim/Survivors Receiving Housing Support

Housing instability and intimate partner violence (IPV) compromise women's sexual and reproductive health (SRH) through reduced contraceptive access and increased risk of unintended pregnancy. This study describes the reproductive health status and needs of IPV survivors receiving housing support and explores factors influencing their experience of reproductive coercion (RC), specifically. Cross-sectional baseline data from a quasi-experimental study of 70 IPV survivors enrolled in housing programs in the Baltimore, MD, metropolitan area from June 2019 through December 2020 were analyzed. Of the 70 women enrolled in the study, 70.3 percent (n = 45) desired to avoid pregnancy, but 57.4 percent were either using no contraceptive method (31.2%) or methods with low effectiveness (26.2%). Approximately, 1 in 6 women (16.4%, n = 11) experienced RC in the past 3 months, which was associated with frequency and severity of IPV (p = 0.001 to 0.005) and PTSD (p = 0.001), as well as not sharing children with the abusive partner (p = 0.002). This study highlights reproductive health risks in an important and under-studied population of women seeking housing due to IPV. Leaving an abusive relationship is a uniquely vulnerable time, and also a time of opportunity, as women are accessing services that can be tailored to their SRH needs. Significant results highlight vulnerability to and consequences of RC in this population. This study has implications for IPV support programs and housing programs that serve women.

Translation and Cross-Cultural Adaptation Protocol of Abuse Questionnaires: The Brazilian Portuguese Version of the Composite Abuse Scale (CAS)

Establishing rigorous translation and cross-cultural adaptation (TCCA) processes for abuse questionnaires is challenging. We propose a methodological TCCA protocol for abuse questionnaires based on our current adaptation of the Composite Abuse Scale (CAS) into Brazilian Portuguese. This 10-step protocol includes: (a) conceptual analysis; (b) double-blinded forward translation; (c) comparison of forward translations; (d) back-translation; (e) developer analysis; (f) specialist committee review; (g) comparison of specialist reviews; (h) cognitive interviews; (i) final reconciliation; and (j) presenting the final version to the developer. We aim to rigorously implement this protocol to achieve a reliable Brazilian Portuguese version of the CAS.

Solvent Vapor Annealing of Amorphous Carbamazepine Films for Fast Polymorph Screening and Dissolution Alteration

Solubility enhancement and thus higher bioavailability are of great importance and a constant challenge in pharmaceutical research whereby polymorph screening and selection is one of the most important tasks. A very promising approach for polymorph screening is solvent vapor annealing where a sample is exposed to an atmosphere saturated with molecules of a specific chemical/solvent. In this work, amorphous carbamazepine thin films were prepared by spin coating, and the transformation into crystalline forms under exposure to solvent vapors was investigated. Employing grazing incidence X-ray diffraction, four distinct carbamazepine polymorphs, a solvate, and hydrates could be identified, while optical microscopy showed mainly spherulitic morphologies. In vitro dissolution experiments revealed different carbamazepine release from the various thin-film samples containing distinct polymorphic compositions: heat treatment of amorphous samples at 80 °C results in an immediate release; samples exposed to EtOH vapors show a drug release about 5 times slower than this immediate one; and all the others had intermediate release profiles. Noteworthy, even the sample of slowest release has a manifold faster release compared to a standard powder sample demonstrating the capabilities of thin-film preparation for faster drug release in general. Despite the small number of samples in this screening experiment, the results clearly show how solvent vapor annealing can assist in identifying potential polymorphs and allows for estimating their impact on properties like bioavailability.

Fabrication of planarly-oriented polycrystalline thin films of smectic liquid crystalline organic semiconductors

Fabrication of planarly-oriented polycrystalline thin films of organic semiconductors was investigated, in which molecules sit parallel, i.e., "face-on" on the substrate so as to allow vertical charge transport favorably through a thin film. With the aid of self-organization of liquid crystalline molecules and an over-coated orientation layer, tens of nm thin films vertically oriented can be re-oriented from "hemeotropic, or vertical" to "homogenous or planar" to achieve polycrystalline thin films planarly oriented after removing the over-coated orientation layer. We investigated the key factors to affect re-orientation of the films and uniformity and surface morphology of the resulting films, including conditions required for the re-orientation and properties of the orientation layer materials and liquid crystals.

Thin film growth studies using time-resolved x-ray scattering

Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

Self-assembled π-conjugated organic nanoplates: from hexagonal to triangular motifs

The formation of triangular nanoplates of an organic semiconducting compound is discussed by considering enhanced solvent/molecule interactions.

Polymorphism of dioctyl-terthiophene within thin films: The role of the first monolayer

The origins of specific polymorphic phases within thin films are still not well understood. The polymorphism of the molecule dioctyl-terthiophene is investigated during the presence of a silicon-oxide surface during the crystallisation process. It is found that a monolayer of molecules forms two-dimensional crystals on the surface. In the case of thicker films crystalline islands are formed, a comparison of the three polymorphic phases observed within thin films and the thermodynamically more stable single crystal phases reveals distinct differences which can be related to an adaption of the molecular packing with the flat surface of the substrate.

Substrate-induced phase of a [1]benzothieno[3,2-b]benzothiophene derivative and phase evolution by aging and solvent vapor annealing

Substrate-induced phases (SIPs) are polymorphic phases that are found in thin films of a material and are different from the single crystal or "bulk" structure of a material. In this work, we investigate the presence of a SIP in the family of [1]benzothieno[3,2-b]benzothiophene (BTBT) organic semiconductors and the effect of aging and solvent vapor annealing on the film structure. Through extensive X-ray structural investigations of spin coated films, we find a SIP with a significantly different structure to that found in single crystals of the same material forms; the SIP has a herringbone motif while single crystals display layered π-π stacking. Over time, the structure of the film is found to slowly convert to the single crystal structure. Solvent vapor annealing initiates the same structural evolution process but at a greatly increased rate, and near complete conversion can be achieved in a short period of time. As properties such as charge transport capability are determined by the molecular structure, this work highlights the importance of understanding and controlling the structure of organic semiconductor films and presents a simple method to control the film structure by solvent vapor annealing.

X-ray structural investigation of nonsymmetrically and symmetrically alkylated [1]benzothieno[3,2-b]benzothiophene derivatives in bulk and thin films

A detailed structural study of the bulk and thin film phases observed for two potential high-performance organic semiconductors has been carried out. The molecules are based on [1]benzothieno[3,2-b]benzothiophene (BTBT) as conjugated core and octyl side groups, which are anchored either symmetrically at both sides of the BTBT core (C8-BTBT-C8) or nonsymmetrically at one side only (C8-BTBT). Thin films of different thickness (8-85 nm) have been prepared by spin-coating for both systems and analyzed by combining specular and grazing incidence X-ray diffraction. In the case of C8-BTBT-C8, the known crystal structure obtained from single-crystal investigations is observed within all thin films, down to a film thickness of 9 nm. In the case of C8-BTBT, the crystal structure of the bulk phase has been determined from X-ray powder diffraction data with a consistent matching of experimental and calculated X-ray diffraction patterns (Rwp = 5.8%). The packing arrangement of C8-BTBT is similar to that of C8-BTBT-C8, that is, consisting of a lamellar structure with molecules arranged in a "herringbone" fashion, yet with lamellae composed of two head-to-head (or tail-to-tail as the structure is periodic) superimposed molecules instead of only one molecule for C8-BTBT-C8. As for C8-BTBT-C8, we demonstrate that the same phase is observed in bulk and thin films for C8-BTBT whatever the film thickness investigated.

Localized crystallization of enantiomeric organic compounds on chiral micro-patterns from various organic solutions

The controlled crystallization of enantiomers of an organic compound (a cyclic phosphoric acid derivative) on templated micro-patterned functionalised surfaces is demonstrated. Areas where a complementary chiral thiol has been located were effective heterogeneous nucleation centres when a solution of the compound is evaporated slowly. Various organic solvents were employed, which present a challenge with respect to other examples when water is used. The solvent and the crystallization method have an important influence on the crystal growth of these compounds. When chloroform was employed, well-defined crystals grow away from the surface, whereas crystals grow in the plane from solutions in isopropanol. In both cases, nucleation is confined to the polar patterned regions of the surface, and for isopropanol growth is largely limited within the pattern, which shows the importance of surface chemistry for nucleation and growth. The apparent dependence on the enantiomer used in the latter case could imply stereo-differentiation as a result of short-range interactions (the templating monolayer is disordered, even at the nanometre scale). The size of the pattern of chiral monolayer also determines the outcome of the crystallization; 5 μm dots are most effective. Despite the low surface tension of the samples (relative to the high surface tension of water), differential solvation of the polar and hydrophobic layers of the solvents allows crystallization in the polar regions of the monolayer, therefore the polarity of the regions in which heterogeneous nucleation takes place is indeed very important. Despite the complex nature of the crystallization process, these results are an important step towards to the use of patterned surfaces for heterogeneous selective nucleation of enantiomers.

Surface Mediated Structures: Stabilization of Metastable Polymorphs on the Example of Paracetamol

The preparation of typically thermodynamically unstable polymorphic structures is a challenge. However, solid surfaces are well established aids for the formation and stabilization of polymorphic structures within, for instance, organic electronics. In this study, we report the stabilization of a pharmaceutically relevant substance via a solid surface at ambient conditions. Form III of paracetamol, which is typically unstable in the bulk at standard conditions, can be stabilized with a model silica surface by a standard spin coating procedure followed by rapid heat treatment. Such a preparation technique allows the use of atomic force microscopy and grazing incidence X-ray diffraction measurements revealing detailed information on the morphology and structure of the polymorph. Furthermore, the results exhibit that this polymorph is stable over a long period of time revealing surface mediated stabilization. These findings demonstrate a novel approach to provide thermodynamic stability when applied to similar molecules with specific applications.

Morphologies of Phenytoin Crystals at Silica Model Surfaces: Vapor Annealing versus Drop Casting

The controlled preparation of different crystal morphologies with varying preferential orientation with respect to the substrate is of crucial importance in many fields of applications. In this work, the controlled preparation of different phenytoin morphologies and the dependency of the preferential orientation of those crystallites is related with the preparation method (solvent annealing vs drop casting), as well as the physical-chemical interaction with the solvents in use. While solvent annealing induces the formation of particular structures that are partially dewetted, the drop casting technique from various solvent results in the formation of needle-like and elongated structures, with each having a distinct morphology. The morphologies are explained via the Hansen solubility parameters and correlated with the solvent vapor pressures. X-ray diffraction experiments reveal preferential orientations with respect to the solid substrate and indicate the surface-mediated stabilization of an unknown polymorph of phenytoin with an elongated unit cell in the b-axis.

Particular film formation of phenytoin at silica surfaces

Given the increasing number of poorly soluble and thus poorly bioavailable active pharmaceutical materials, there is a demand for innovative formulation platforms for such molecules. Thus a focus on enhancing dissolution properties of poorly soluble drugs exists. Within this study, the spin coating of acetone solutions containing 5,5-diphenyl-2,4-imidazolidinedione (phenytoin) in various concentrations is evaluated. The results reveal strong variations of the morphology of deposited phenytoin crystals at silica surfaces. Individual separated particles are obtained on low phenytoin concentrations, and closely packed particular films form when the concentration is increased. As the material is isomorphic, these various morphologies have the same crystalline structure. Dissolution experiments reveal that both the apparent maximum solubility and as the dissolution rate are strongly enhanced compared to bulk powder, suggesting that formulation based on this preparative technique will allow overcoming the low solubility problematic for a variety of drugs.

Controlling the growth mode of para-sexiphenyl (6P) on ZnO by partial fluorination

Partial fluorination of para-sexiphenyl significantly alters the growth process on ZnO(101̄0) avoiding the phase coexistence of unsubstituted para-sexiphenyl and leading to smooth layer-by-layer growth.