A self-reporting polythiourethane/tetrapodal-ZnO (PTU/T-ZnO) composite is produced using spiropyran as an additive at a concentration as low as 0.5 wt %. Exposure to heat, UV light and mechanical force caused the spiropyran to undergo reversible isomerization indicated by a reversible color change. The studies have been conducted with a constant spiropyran concentration at 0.5 wt %, meanwhile varying the T-ZnO concentration from 0 to 7.5 wt %. The tetrapodal ZnO served as a prism: the light scattering effect of T-ZnO created a visual impression of uniform color distribution. The interconnected network of the tetrapodal of ZnO embedded in the PTU matrix enhanced the mechanical stability of the polymer leading to high impact resistance up to ∼232 kPa. PTU/spiropyran also emerged as a possible thermal sensing coating, due to its temperature sensitivity. Due to the broad green luminescence band (∼535 nm) in T-ZnO, the colored merocyanine form which absorbs in this region of the spectrum switches back to spiropyran at this wavelength. High concentrations of T-ZnO were shown to reduce the effect one of the switching triggers i.e., ultraviolet light. Using this property of T-ZnO it was possible to achieve a switchable system with the possibility of separating the stimuli.

Spiropyrans are dyes that can be reversibly switched to a highly colored merocyanine form by a number of stimuli such as light, mechanical force or temperature. To make use of these molecules, there is a requirement to functionalize them appropriately. Herein we report a library of spiropyrans bearing two (pseudo)halide functional groups on either half of the molecule. Such halide substituents are valuable, because they themselves may be used as reactive sites in cross-coupling reactions, for example. Different combinations of halides, for which different reactivities in cross-coupling reactions may be expected, will facilitate selective consecutive cross-coupling reactions and condensations. Data concerning the UVvis characteristics, the photostationary equilibria of the materials as well as the half-life of the merocyanine forms in solution are presented.

A nucleophile‐selective cross‐coupling reaction on an aromatic compound bearing two metal groups, Bpin and SnMe3, has been developed. Previously, only aryl bromides and iodides could be used as electrophilic components, but in this work, the scope could be extended to vinyl and alkynyl bromides as electrophiles. This means that the roles typical in Sonogashira couplings or Heck reactions of the aromatic ring as the dielectrophile coupling to vinyl and alkynyl metal species are reversed, which presents a new tool for organic synthesis. The first nucleophilic site to react is the stannyl group, and subsequently, a Suzuki–Miyaura cross‐coupling reaction can take place on the same molecule.

Erstmalige Beschreibung des photomechanischen Effekts [7]. Ein Diazobenzolfarbstoff Eyring bereits 1940 zu der bemerkenswerten Hypothese, dass unter den angewandten rheologischen Bedingungen so hohe Zugkräfte entlang der Kette auftraten, dass diese reißen konnten, was zu kürzeren Segmenten führte.Schon seit den 1930er Jahren war bekannt, dass Ultraschall in einer Polymerlösung zu einer Kettenverkürzung führt. Jedoch erst in den 1970er Jahren wurden die zugehörigen Mechanismen der Kraftübertragung genauer untersucht [5]. Die Ergebnisse schlugen sich aber nicht in einem breiteren Interesse an dem Phänomen nieder. Erst in den 1990er Jahren wurde von Smith das Verhalten von Polymeren in Lösung unter Ultraschall detailliert untersucht. Hierbei zeigte sich, dass die beobachtete Kettenverkürzung von Parametern wie Lösungsmittel, Konzentration der Polymere oder Intensität des Ultraschalls abhängt [6].Der nächste große Schritt in der Untersuchung von mechanischen Effekten in Polymeren erfolgte mit der Beobachtung des photomechanischen Effekts in Nylon 1966 [7]. Hierbei zeigte ein aus Nylonfäden gewebtes Band mit einem nicht kovalent eingelagerten, dispergierten Diazoniumfarbstoff 1 bei Belichtung eine Längenänderung (Abbildung 1

Substrate. -A nucleophile-selective cross--coupling reaction of dinucleophilic thiophene (I) with vinyl and alkynyl bromides is developed, extending the scope of electrophiles usable in Sonogashira-or Heck-type coupling reactions. This reversal of the roles of the coupling partners represents a new tool for organic synthesis. The first nucleophilic site to react is the stannyl group and subsequent Suzuki-Miyaura cross-coupling reactions can be carried out to provide difunctionalized thiophenes in a one-pot manner. -(HE, L.-Y.; SCHULZ-SENFT, M.; THIEDEMANN, B.; LINSHOEFT, J.; GATES, P. J.; STAUBITZ*, A.; Eur. J. Org. Chem. 2015, 11, 2498-2502, http://dx.