New synthesis of benzo[1,2-b:4,5-b′]dithiophene (BDT)

Thiophene-containing polycondensed aromatic compounds are important source of functional organic materials for different applications. Within this class of molecules, benzo[1,2-b:4,5-b\u2032]dithiophene (BDT, figure 1) is recognized as one of the most successful building blocks in the synthesis of highly efficient photovoltaic and semiconducting materials.1 In fact the rigid and planar conjugated structure of BDT makes it attractive for achieving highly tunable molecular energy levels and optical band gaps as well as high hole mobilities. In recent years, benzannulation and thieannulation approaches, involving several steps, have been applied to the synthesis of BDT and of \uf070-extended thienoacenes,2 but the search of alternative easy access to this class of heterocycles is always a valuable synthetic target. We present here a new two-step synthesis of BDT, starting from 3-thiophene carbaldehyde as unique thiophene precursor. Although the second step of the synthesis needs to be optimized, this new methodology is certainly competitive to the classical approach3 which involves four steps, more expensive reagents and gives a comparable overall yield. In addition, the use of different hetero/aromatic aldehydes in the reaction with intermediate 2 gives access to a series of thiophene benzocondensed heterocycles

Axially chiral benzo[1,2-b:4,3-b’]dithiophene derivatives: a new route to tetrathiahelicenes

Thiophene-containing fused aromatic compounds represent an interesting class of \u3c0-conjugated systems in functional organic materials [1]. Among them, benzo[1,2-b:4,3-b\u2019]dithiophene (BDT) and its derivatives are by far the most widely studied, especially as units in mono and polydisperse oligomers in the field of the materials science [2], and as \u3c0-spacers in push-pull organic chromophores for photovoltaic applications [3]. Moreover, BDT is a key intermediate for the synthesis of inherently chiral helical systems such as tetrathia[7]helicenes 3 [4]. For all these reasons, BDT can be identified as a key starting molecule that, through a judicious functionalization of the \u3b1-positions of the thiophene rings, can allow access to more complex and interesting systems. Exploiting the experience acquired in our laboratories on the synthesis and functionalization of BDT derivatives [5,6], we have studied a novel and simple synthetic route to prepare bis(benzo[1,2-b:4,3-b\u2019]dithiophene) systems 2, through Pd-catalyzed cross coupling reactions, starting from bromides 1 (Figure 1).This strategy provides a convenient route to an interesting class of chiral atropisomeric heterobiaryl derivatives 2 with C2-symmetry, which can be used as starting reagents for an innovative non-photochemical synthesis of tetrathiahelicenes exploiting a Suzuki-Miyaura cross coupling and a Pd-catalyzed annulation with internal alkynes as key steps.. Asymmetric versions of this synthesis is under study

CHiral bis-benzo[1,2-b:4,3-b’]dithiophenes : synthesis and stereochemical properties

Thiophene-containing fused aromatic compounds are an interesting class of \u3c0-conjugated systems with applications in functional organic materials.1 Among them, benzo[1,2-b:4,3-b\u2019]dithiophene (BDT) and its derivatives are widely studied in the field of materials science,2 and for photovoltaic applications.3 Moreover, BDT is a key intermediate for the synthesis of inherently chiral helical systems such as tetrathia[7]helicenes.4 In our ongoing studies on the synthesis and functionalization of BDTs,5 we have developed a novel and convenient route to prepare an interesting class of chiral heterobiaryl bis(benzo[1,2-b:4,3-b\u2019]dithiophene) systems 2 and 3 (Figure 1). In this communication we will report the synthesis of compounds 2 and 3 along with the study of their chiroptical properties. Bromides 3 are also expected to have potential applications in asymmetric reactions, including the enantioselective synthesis of tetrathia[7]helicene derivatives

Axially chiral benzo[1,2-b:4,3-b’]dithiophene derivatives as key intermediates for enantiopure tetrathia[7]helicenes

Thiophene-containing fused aromatic compounds are an interesting class of \u3c0-conjugated systems with applications in functional organic materials.1 Among them, benzo[1,2-b:4,3-b\u2019]dithiophene (BDT) and its derivatives are widely studied, for instance as units in mono and polydisperse oligomers in the field of materials science,2 and as \u3c0-spacers in push-pull organic chromophores for photovoltaic applications.3 Furthermore, BDT is a key intermediate for the synthesis of inherently chiral helical systems such as tetrathia[7]helicenes.4 Thus, BDT can be identified as a key starting molecule, which can allow access to more complex and interesting systems through a judicious functionalization of the \u3b1-position of the thiophene rings. In our ongoing studies on the synthesis and functionalization of BDTs,5 we have developed a novel synthesis to prepare systems 2, starting from bromides 1 (Figure 1). Compounds 2 are an interesting class of chiral atropisomeric heterobiaryl derivatives with C2-symmetry, which can be selectively functionalized into bromides 3, starting reagents for an innovative non-photochemical synthesis of tetrathiahelicenes through Pd-catalysed annulation with internal alkynes as key step. Asymmetric versions of this synthesis is under study thanks to the chiroptical properties of 3, which represent useful intermediates for the enantioselective synthesis of the corresponding tetrathiahelicene derivatives

Chiral bis(benzo[1,2-b:4,3-b’]dithiophene)s: synthesis and stereochemical characterization

Thiophene-containing fused aromatic compounds are an interesting class of \uf070-conjugated systems in functional organic materials (1). Among them, benzo[1,2-b:4,3-b\u2019]dithiophene (BDT) and its derivatives are widely studied, for instance as units in mono and polydisperse oligomers in the field of the materials science (2), and as \uf070-spacers in push-pull organic chromophores for photovoltaic applications (3). Furthermore, BDT is a key intermediate for the synthesis of inherently chiral helical systems such as tetrathia[7]helicenes (4).Thus, BDT can be identified as a key starting molecule, which can allow access to more complex and interesting systems through a judicious functionalization of the \uf061-positions of the thiophene rings. In our ongoing studies on the synthesis and functionalization of BDTs (5,6), we have developed a novel synthesis to prepare bis(benzo[1,2-b:4,3-b\u2019]dithiophene) systems 2, starting from bromides 1 (Figure 1).Compounds 2 belong to an interesting class of chiral atropisomeric heterobiaryl derivatives with C2-symmetry, which can be selectively functionalized into bromides 3. The chiroptical properties of both systems 2 and 3 have been fully elucidated by experimental and theoretical studies. On the other hand, enantiopure bromides 3 represent useful intermediates for the enantioselective synthesis of the corresponding tetrathiahelicene derivatives

Voices of Occupiers/Liberators: the BBC's radio propaganda in Italy between 1942 and 1945

The ambiguity of the role played by British propaganda in Italy during the Second World War is clearly reflected in the phenomenon of Radio London. While Radio London raised the morale of the Italian civilians living under the Fascist regime and provided them with alternative information on the conflict, the microphones of the BBC were also used by the British government to address a country they were planning to occupy. In this article, I will analyse the occupation/liberation operations that were run at the BBC Italian Service from two separate angles. On the one hand, the analysis of the programmes broadcast between the months preceding the Allies’ landing in Sicily and the actual occupation shows how the Allies built their image as liberators and guarantors of better living conditions. On the other, the analysis of the relationships between the Foreign Office and the anti-Fascist exiles reveals that the Italian BBC broadcasters were not always allowed to freely express their political opinion or to dispose of their own lives

Silencing TRPM7 mimics the effects of magnesium deficiency in human microvascular endothelial cells

Evidence has accumulated to suggest that magnesium might play a role in controlling angiogenesis. Since microvascular endothelial cells are protagonists in this process, we investigated the behavior of these cells cultured in low extracellular magnesium or silenced for its transporter Transient Receptor Potential Melastatin (TRPM)7, essential for cellular magnesium homeostasis. In particular, we focused on some crucial steps of the angiogenic process, i.e. proliferation, migration, protease production and organization in tridimensional structures. Silencing TRPM7 mimics the effects of low extracellular magnesium on human microvascular endothelial cells (HMEC). Indeed, while no effects were observed on the production of metalloproteases and on tridimensional organization on matrigel, both magnesium deficiency and silencing of TRPM7 impair cell migration and inhibit growth by arresting the cells in the G0/ G1 and G2/M phases of the cell cycle. Since low extracellular magnesium markedly decreases TRPM7 in HMEC, we suggest that TRPM7 downregulation might mediate low magnesium-induced inhibition of cell growth and migration. Human endothelial cells from the umbilical vein are growth inhibited by low magnesium and growth stimulated after TRPM7 silencing. An impairment of ERK phosphorylation in HMEC silencing TRPM7 is responsible, in part, for the different proliferative behavior of these two cell types. We broadened our studies also to endothelial colony-forming cells and found that they are sensitive to fluctuations of the concentrations of extracellular magnesium, while their proliferation rate is not modulated by TRPM7 silencing. Our results point to magnesium and TRPM7 as a modulators of the angiogenic phenotype of microvascular endothelial cells

Downregulation of HD-PTP by high magnesium concentration : novel insights into magnesium-induced endothelial migration

Magnesium promotes endothelial migration, an event which is orchestrated by a complex interplay between protein tyrosine kinases and phosphatases. We found that high extracellular concentrations of magnesium do not modulate the levels and the activation of FAK and Src, two tyrosine kinases involved in driving cell migration. Interestingly, we show that magnesium induced-endothelial motility correlates with the downregulation of HD-PTP, a potential tyrosine phopshatase previously shown to be involved in modulating cell migration. The decreased amounts of HD-PTP are not dependent upon transcriptional mechanisms. In contrast to Fibroblast Growth Factor-induced HD-PTP downregulation, the proteasome seems not to be involved in regulating HD-PTP levels in endothelial cells cultured in high magnesium containing medium. Our results indicate that, in the presence of high magnesium concentrations, endothelial cells are stimulated to migrate through complex mechanisms involving also HD-PTP