Towards supramolecular design of organic semiconductors

Organic molecules with extended -conjugation can display unusual electronic properties, traditionally associated with solid state inorganic materials. Manipulating a molecular structure, one can design organic metals, semiconductors or superconductor, magnetic, non-linear optical and lasing materials and even combine several of these properties in a single material. Such behavior of “-functional” materials has already led to a number of technologies, eg. organic light-emitting diodes (OLED), field-effect transistors (OFET) and photovoltaics (OPV). However, the optimization of these properties and the performance of corresponding devices relies not only on a fine-tuned molecular structure but also on a difficult-to-control supramolecular organization in the solid state. Achieving such control, via molecular engineering of the building blocks, studies of their self-assembly by scanning probe and diffraction methods will be the focus of this lecture. I will discuss how a combination of molecular, supramolecular, and nano/mesoscopic structure of organic semiconductors affects their electronic properties and device performance. I will describe our approaches to control the co-assembly of donor and acceptor semiconducting molecules, on surfaces (studied by STM) and in 3D crystals (studied by XRD). Finally, I will present our related work on synthesis of epitaxially ordered molecular wires and two-dimensional conjugated polymers by surface-confined polymerization.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Low-threshold organic laser based on an oligofluorene truxene with low optical losses

A blue-emitting distributed feedback laser based on a star-shaped oligofluorene truxene molecule is presented. The gain, loss, refractive index, and (lack of) anisotropy are measured by amplified spontaneous emission and variable-angle ellipsometry. The waveguide losses are very low for an organic semiconductor gain medium, particularly for a neat film. The results suggest that truxenes are promising for reducing loss, a key parameter in the operation of organic semiconductor lasers. Distributed feedback lasers fabricated from solution by spin-coating show a low lasing threshold of 270 W/cm(2) and broad tunability across 25 nm in the blue part of the spectrum

Improvement of treatment of rosacea patients by means of andministering angioprotective and hepatoprotective agents

Rosacea (acne) is a widespread chronic dermatosis. Its clinical manifestation is localized on open skin areas – central parts of the face (cheeks, nose, and chin). It has a negative effect on psychoemotional condition of patients, reduces their ability to work and social activity. Today rosacea is characterized by a long chronic course, resistance to standard therapy. Therefore, improvement of the effect of treatment of patients with rosacea is a topical issue of modern dermatology. Rosacea is found to be a multifactorial dermatosis. Its pathogenesis includes such important signs as changes of the skin microcirculation, vegetative dysfunctions, neuroendocrine regulation disorders, functional disorders of the digestive organs, which should be considered in a comprehensive examination and treatment of patients

Copper-catalyzed asymmetric sp3 C-H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

We are grateful to the Canada Research Chair (Tier 1) foundation (to C.-J. Li), NSERC, CFI, and FQRNT (CCVC) for their support of our research.This report describes a highly enantioselective oxidative sp3 C-H arylation of N-aryltetrahydroisoquinolines (THIQs) through a dual catalysis platform. The combination of the photoredox catalyst, [Ir(ppy)2(dtbbpy)]PF6, and chiral copper catalysts provide a mild and highly effective sp3 C-H asymmetric arylation of THIQs.Publisher PDFPeer reviewe

Self-assembly of PS-PVP block copolymers and their complexes at the air/water interface

Une compréhension approfondie et un meilleur contrôle de l'auto-assemblage des copolymères diblocs (séquencés) et de leurs complexes à l'interface air/eau permettent la formation contrôlée de nanostructures dont les propriétés sont connues comme alternative à la nanolithographie. Dans cette thèse, des monocouches obtenues par les techniques de Langmuir et de Langmuir-Blodgett (LB) avec le copolymère dibloc polystyrène-poly(4-vinyl pyridine) (PS-PVP), seul ou complexé avec de petites molécules par liaison hydrogène [en particulier, le 3-n-pentadécylphénol (PDP)], ont été étudiées. Une partie importante de notre recherche a été consacrée à l'étude d'une monocouche assemblée atypique baptisée réseau de nanostries. Des monocouches LB composées de nanostries ont déjà été rapportées dans la littérature mais elles coexistent souvent avec d'autres morphologies, ce qui les rend inutilisables pour des applications potentielles. Nous avons déterminé les paramètres moléculaires et les conditions expérimentales qui contrôlent cette morphologie, la rendant très reproductible. Nous avons aussi proposé un mécanisme original pour la formation de cette morphologie. De plus, nous avons montré que l'utilisation de solvants à haut point d’ébullition, non couramment utilisés pour la préparation des films Langmuir, peut améliorer l'ordre des nanostries. En étudiant une large gamme de PS-PVP avec des rapports PS/PVP et des masses molaires différents, avec ou sans la présence de PDP, nous avons établi la dépendance des types principaux de morphologie (planaire, stries, nodules) en fonction de la composition et de la concentration des solutions. Ces observations ont mené à une discussion sur les mécanismes de formation des morphologies, incluant la cinétique, l’assemblage moléculaire et l’effet du démouillage. Nous avons aussi démontré pour la première fois que le plateau dans l'isotherme des PS-PVP/PDP avec morphologie de type nodules est relié à une transition ordre-ordre des nodules (héxagonal-tétragonal) qui se produit simultanément avec la réorientation du PDP, les deux aspects étant clairement observés par AFM. Ces études ouvrent aussi la voie à l'utilisation de films PS-PVP/PDP ultraminces comme masque. La capacité de produire des films nanostructurés bien contrôlés sur différents substrats a été démontrée et la stabilité des films a été vérifiée. Le retrait de la petite molécule des nanostructures a fait apparaître une structure interne à explorer lors d’études futures.Deeper understanding and control of the self-assembly of diblock copolymers and their complexes at the air/water interface allow the formation of nanopatterns with known properties to provide a competitive substitute to nanolithography. In this dissertation, Langmuir and Langmuir-Blodgett (LB) monolayers obtained from polystyrene-poly(4-vinyl pyridine) diblock copolymers (PS-PVP), alone and hydrogen-bonded by various small molecules [particularly, 3-n-pentadecylphenol (PDP)], have been extensively investigated. A major part of the research was devoted to the study of an uncommon monolayer pattern that we term the nanostrand network. LB monolayers consisting of nanostrands have sometimes been reported in the literature, but are often coexistent with other morphologies, which is not useful for potential applications. We have determined the molecular parameters and experimental conditions that control this morphology, making it highly reproducible, and have proposed a novel mechanism for the formation of this morphology. In addition, we have shown that the use of high-boiling spreading solvents, not usually used for Langmuir film preparation, can improve the nanostrand order. By investigation of a wide range of PS-PVP’s with various block ratios and molecular weights, with and without PDP present, we have established the composition dependence of the main LB morphology types (planar, nanostrand, nanodot) and the influence of each type on spreading solution concentration. This led to an extensive discussion concerning the mechanisms of morphology formation, including kinetic, molecular association, and dewetting contributions. We have also shown that the isotherm plateau transition for nanodot-forming PS-PVP/PDP is related to an order–order transition that occurs simultaneously with PDP reorientation, both aspects being clearly observed by AFM. These studies also form the basis for the use of ultrathin PS-PVP/PDP films as templates. The ability to produce well-controlled nanopatterned films on various substrates has been demonstrated, and film stability has been verified. Removal of small molecules from the nanostructures has revealed the appearance of new substructure of interest for further study