Challenges in Lifestyle Migration Research: Reflections and Findings about the Spanish Crisis

The lifestyle migration conceptual framework is based on the motivation for moving reported by the migrants themselves. We discuss the operability of this approach, which is built on the subjective assessments of individuals. It diminishes the actual importance of economic factors and has an underlying ideological element associated with the categorisation of people according to their nationality. A comparative analysis of residential variations by nationalities between 2005 and 2010 in Alicante (Spain) shows that, when faced with the economic crisis, the so-called lifestyle migrants are changing their mobility patterns in a way similar to the rest of the migrants. This calls into question the adequacy of juxtaposing lifestyle and labour migration. Both theory and research show that this duality, instead of clarifying applied research, makes it more difficult. We argue that the lifestyle migration framework is inadequate to study changes in mobility patterns, particularly when using a quantitative approach.

Bis(arylene-ethynylene)-s-tetrazines: A Promising Family of n-Type Organic Semiconductors?

We theoretically describe in this work the n-type semiconducting behavior of a set of bis(arylene-ethynylene)-s-tetrazines ((ArCC)2Tz), by comparing their electronic properties with those of their parent diaryl-s-tetrazines (Ar2Tz) after the introduction of ethynylene bridges. The significantly reduced internal reorganization energy for electron transfer is ascribed to an extended delocalization of the LUMO for (ArCC)2Tz as opposite to that for Ar2Tz, which was described mostly localized on the s-tetrazine ring. The largest electronic coupling and the corresponding electron transfer rates found for bis(phenyl-ethynylene)-s-tetrazine, as well as for some halogenated derivatives, are comparable to those reported for the best performing n-type organic semiconductor materials such as diimides and perylenes. The theoretical mobilities for the studied compounds turn out to be in the range 0.3–1.3 cm2 V–1 s–1, close to values experimentally determined for common n-type organic semiconductors used in real devices. In addition, ohmic contacts can be expected when these compounds are coupled to metallic cathodes such as Na, Ca, and Sm. For these reasons, the future application of semiconducting bis(phenyl-ethynylene)-s-tetrazine and its fluorinated and brominated derivatives in optoelectronic devices is envisioned.