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The electronics era is flourishing and morphing itself into Internet of Everything, IoE. At the same time, questions arise on the issue of electronic materials employed: especially their natural availability and low-cost fabrication, their functional stability in devices, and finally their desired biodegradation at the end of their life cycle. Hydrogen bonded pigments and natural dyes like indigo, anthraquinone and acridone are not only biodegradable and of bio-origin but also have functionality robustness and offer versatility in designing electronics and sensors components. With this Perspective, we intend to coalesce all the scattered reports on the above-mentioned classes of hydrogen bonded semiconductors, spanning across several disciplines and many active research groups. The article will comprise both published and unpublished results, on stability during aging, upon electrical, chemical and thermal stress, and will finish with an outlook section related to biological degradation and biological stability of selected hydrogen bonded molecules employed as semiconductors in organic electronic devices. We demonstrate that when the purity, the long-range order and the strength of chemical bonds, are considered, then the Hydrogen bonded organic semiconductors are the privileged class of materials having the potential to compete with inorganic semiconductors. As an experimental historical study of stability, we fabricated and characterized organic transistors from a material batch synthesized in 1932 and compared the results to a fresh material batch.

Diminishing fossil fuel reserves and the increase in their consumption indicate that strategies need to be developed to produce biofuels from renewable resources. Biodiesel offers advantages over other petroleum-derived fuel substitutes, because it is comparatively environmentally friendly and an excellent fuel for existing diesel engines. Biodiesel, which consists of fatty acid methyl esters (FAMEs), is usually obtained from plant oils. However, its extensive production from oil crops is not sustainable because of the impact this would have on food supply and the environment. Microbial oils are postulated as an alternative to plant oils, but not all oleaginous microorganisms have ideal lipid profiles for biodiesel production. On the other hand, lipid profiles could be modified by genetic engineering in some oleaginous microorganisms, such as the fungus Mucor circinelloides, which has powerful genetic tools. We show here that the biomass from submerged cultures of the oleaginous fungus M. circinelloides can be used to produce biodiesel by acid-catalyzed direct transformation, without previous extraction of the lipids. Direct transformation, which should mean a cost savings for biodiesel production, increased lipid extraction and demonstrated that structural lipids, in addition to energy storage lipids, can be transformed into FAMEs. Moreover, the analyzed properties of the M. circinelloides-derived biodiesel using three different catalysts (BF 3 , H 2 SO 4 , and HCl) fulfilled the specifications established by the American standards and most of the European standard specifications.

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Transesterification of refined and crude vegetable oils was carried out with a sulfonic acid-modified mesostructured catalyst. This catalyst has yielded fatty acid methyl ester (FAME) purity over 95 wt % for oil conversion close to 100% under best reaction conditions (temperature 180 °C, methanol/oil molar ratio 10, and catalyst loading 6 wt % with regard to the amount of oil). Interestingly, high methanol concentration leads to a detrimental effect on the catalyst activity. Regardless of the presence of free fatty acids, the sulfonic acid-modified mesostructured catalyst showed high activity toward simultaneous esterification and transesterification. These sulfonated mesostructured materials are promising catalysts for preparation of biodiesel, but some aspects related to the tuning of the adsorption properties of the silica surface and the enhancement of the catalyst's reusability must be addressed in future work.

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