Building blocks and COFs formed in concert —Three‐component synthesis of pyrene‐fused Azaacene covalent organic framework in the bulk and as films

A three‐component synthesis methodology is described for the formation of covalent organic frameworks (COFs) containing extended aromatics. Notably, this approach enables synthesis of the building blocks and COF along parallel reaction landscapes, on a similar timeframe. The use of fragmental building block components, namely pyrene dione diboronic acid as aggregation‐inducing COF precursor and the diamines o‐phenylenediamine (Ph), 2,3‐diaminonaphthalene (Naph), or (1R,2R)‐(+)‐1,2‐diphenylethylenediamine (2Ph) as extending functionalization units in conjunction with 2,3,6,7,10,11‐hexahydroxytriphenylene, resulted in the formation of the corresponding pyrene‐fused azaacene, i.e., Aza‐COF series with full conversion of the dione moiety, long‐range order, and high surface area. In addition, the novel three‐component synthesis was successfully applied to produce highly crystalline, oriented thin films of the Aza‐COFs with nanostructured surfaces on various substrates. The Aza‐COFs exhibit light absorption maxima in the blue spectral region, and each Aza‐COF presents a distinct photoluminescence profile. Transient absorption measurements of Aza‐Ph‐ and Aza‐Naph‐COFs suggest ultrafast relaxation dynamics of excited‐states within these COFs.Deutsche Forschungsgemeinschaft | Ref. ME 4515/1-2Fundação para a Ciência e a Tecnologia | Ref. SFRH/BD/141865/2018Fundação para a Ciência e a Tecnologia | Ref. PTDC/QUI-OUT/2095/2021Fundação para a Ciência e a Tecnologia | Ref. UIDB/50011/2020Fundação para a Ciência e a Tecnologia | Ref. UIDP/50011/2020Fundação para a Ciência e a Tecnologia | Ref. LA/P/0006/2020National Science Foundation (EE.UU.) | Ref. DMR-1848067Engineering and Physical Sciences Research Council (Reino Unido) | Ref. EP/V055127/1Agencia Estatal de Investigación | Ref. RYC2020-030414-IUniversidade de Vigo/CISU

Building Blocks and COFs Formed in Concert-Three-Component Synthesis of Pyrene-Fused Azaacene Covalent Organic Framework in the Bulk and as Films.

A three-component synthesis methodology is described for the formation of covalent organic frameworks (COFs) containing extended aromatics. Notably, this approach enables synthesis of the building blocks and COF along parallel reaction landscapes, on a similar timeframe. The use of fragmental building block components, namely pyrene dione diboronic acid as aggregation-inducing COF precursor and the diamines o-phenylenediamine (Ph), 2,3-diaminonaphthalene (Naph), or (1R,2R)-(+)-1,2-diphenylethylenediamine (2Ph) as extending functionalization units in conjunction with 2,3,6,7,10,11-hexahydroxytriphenylene, resulted in the formation of the corresponding pyrene-fused azaacene, i.e., Aza-COF series with full conversion of the dione moiety, long-range order, and high surface area. In addition, the novel three-component synthesis was successfully applied to produce highly crystalline, oriented thin films of the Aza-COFs with nanostructured surfaces on various substrates. The Aza-COFs exhibit light absorption maxima in the blue spectral region, and each Aza-COF presents a distinct photoluminescence profile. Transient absorption measurements of Aza-Ph- and Aza-Naph-COFs suggest ultrafast relaxation dynamics of excited-states within these COFs

Building Blocks and COFs Formed <i>in Concert</i>—Three‐Component Synthesis of Pyrene‐Fused Azaacene Covalent Organic Framework in the Bulk and as Films

AbstractA three‐component synthesis methodology is described for the formation of covalent organic frameworks (COFs) containing extended aromatics. Notably, this approach enables synthesis of the building blocks and COF along parallel reaction landscapes, on a similar timeframe. The use of fragmental building block components, namely pyrene dione diboronic acid as aggregation‐inducing COF precursor and the diamines o‐phenylenediamine (Ph), 2,3‐diaminonaphthalene (Naph), or (1R,2R)‐(+)‐1,2‐diphenylethylenediamine (2Ph) as extending functionalization units in conjunction with 2,3,6,7,10,11‐hexahydroxytriphenylene, resulted in the formation of the corresponding pyrene‐fused azaacene, i.e., Aza‐COF series with full conversion of the dione moiety, long‐range order, and high surface area. In addition, the novel three‐component synthesis was successfully applied to produce highly crystalline, oriented thin films of the Aza‐COFs with nanostructured surfaces on various substrates. The Aza‐COFs exhibit light absorption maxima in the blue spectral region, and each Aza‐COF presents a distinct photoluminescence profile. Transient absorption measurements of Aza‐Ph‐ and Aza‐Naph‐COFs suggest ultrafast relaxation dynamics of excited‐states within these COFs.</jats:p

Rivalry, antagonism and war in the nation- and state-building process: the H factor in the relations between Eritrea and Ethiopia

The tragic outbreak of violence between Eritrea and Ethiopia in 1998 and the subsequent dramatic conflict that has locked the two states until 2000, and still hoover over the economic and social development of the Horn of Africa, has taken political analysts, specialists of the region and the media aback. Therefore the most recurrent words used to explain those feelings have been shock, dismay, delusion betrayal etc. However, this highly unexpected and to a certain extent surprising development has not generated a similarly strong desire for a deep understanding of its generating factor. On the opposite the media and to a certain extent even many political analysts have often opted for a rather superficial explanation dismissing this conflict with few contemptuous statements focusing on the personal rivalry between the leaders of the two nations or on the allegedly proactive and over-assertive policy of the young Eritrean state. These kind of judgements could be best epitomised by the catching image of \u201ctwo bald men fighting over a comb\u201d used by the Financial Times to describe the conflict between Eritrea and Ethiopia.1 In the intentions of the journalist this statement emphasised the futility of the conflict and, indirectly pointed out at the destitute economy of both countries. It is no coincidence that both Eritrea's and Ethiopia's leaders reacted angrily at this definition and called for a more complex and analytical understanding of the conflict, though offering different and, predictably contrasting interpretations. Without undermining the relevance of contemporary political issues the recent conflict between Eritrea and Ethiopia ought to be analysed also through different lenses and to this analysis chronological depths is a key prerequisite. It is my strong belief that historians can provide additional elements for an understanding of this conflict by locating it within the perspective of the long dur\ue9e of historical developments. To this end it is crucial to address issues such as land, regional systems of power, the impact of colonialism, the formation and role of political elites and the paths toward state and nation-building. It is only within this specific, yet very complex framework, that historians can contribute in shedding some light on this complex and painful event. To a deeper and satisfactory understanding of the specific and immediate causes of the conflict the access to official and private documents remain a prerequisite which, unfortunately, will be possible to satisfy only after many years. My paper is an attempt to contribute toward this analysis from a historical perspective. I will argue that, though the 1998 \u2013 2000 conflict bears elements of specificity related to contemporary regional and international politics, important elements of understanding can be retrieved through a broader retrospective gaze focusing on the way historical elements of rivalry and antagonism have sedimented through time shaping the nature of relationship between Eritrea and Ethiopia. The main point that I will try to make is that those elements of rivalry and even antagonism should not be interpreted in mechanist terms as necessary causes for the recent conflict but rather as successive layers of tension and uneasiness that within given geopolitical balances (or unbalances) of powers could also represent the platform for conflicting relations