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

Effects of cytokinins, cytokinin ribosides and their analogs on the viability of normal and neoplastic human cells

We examined the effects of some cytokinins and cytokinin ribosides including a series of adenosine analogs differently substituted in the N(6) position, along with some hypoxanthine derivatives on the viability of normal and neoplastic human cells. Cytokinins such as trans-zeatin, isopentenyladenine and benzyladenine do not show any effect, while cytokinin ribosides such as trans-zeatin riboside, isopentenyladenosine, and benzylaminopurine riboside impair the viability of normal and neoplastic cells, apart from colon carcinoma LoVo cells

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

A comparative study of electrochemical, spectroscopic and structural properties of phenyl, thienyl and furyl substituted ethylenes

a detailed electrochemical and photophysical comparative study of three parallel series of phenyl, thienyl and furyl substituted ethylenes has been carried out, implemented by the computational calculation of selected terms. Relationships have been highlighted between molecular structure (number and type of aromatic rings) and important functional properties (in particular, electronic features and oligomerization ability). Interestingly, some of the studied heteroaryl-ethylenes show emission in the solid state displaying an aggregation-induced emission behavior

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

MAGNESIUM AND ENDOTHELIAL FUNCTION: COMPARATIVE STUDIES IN MACRO AND MICROVASCULAR ENDOTHELIAL CELLS

Mg is referred to as the intracellular divalent cation par excellence. Its biological role is extremely versatile as it can serve structural functions as well as dynamic functions. Accordingly, Mg deficiency has been reported to be involved in the pathogenesis of cardiovascular diseases and, in particular, in atherogenesis. 1)Mg in macrovascular endothelial cells. In cultured macrovascular endothelial cells, low Mg increases tha adhesion of monocytes to the monolayer via upregulation of vascular cell adhesion molecule (VCAM), induces plasminogen activator inhibitor (PAI)1, augments the levels of the pro-inflammatory cytokine interleukin (IL)-1\u3b1, impairs endothelial proliferation and promotes cellular senescence (Killilea DW and Ames BN, 2008). Recently, endothelial function has been shown significantly impaired in a model of inherited hypomagnesemia in mice (MgL mice) (Mazur A et al., 2007). All these results point to the fact that low Mg promotes the acquisition of an inflammatory phenotype in endothelium. Since NFkB transcription factors control the inflammatory response and are activated by free radicals, I investigated whether culture in low Mg promotes oxidative stress and activates NFkB in human umbilical vein endothelial cells (HUVEC). Because NFkB activation correlates with marked alterations of the cytokine network, I also studied the secretion profile of inflammatory molecules in cells grown in low Mg. My results highlight molecular events that contribute to the pro-atherogenic effect of Mg deficiency. 2)Mg in microvascular endothelial cells. MEC contribute to inflammation by elaborating cytokines, synthesizing chemical mediators and expressing adhesion molecules which bind leukocytes, thus facilitating their passage in the nearby tissues. In addition, also in the microvasculature the endothelium itself is sensitive to cytokines which profoundly affect its behavior. Low extracellular Mg affects also microvascular endothelial cells. In murine microvascular cells, it has been reported that low Mg induces the synthesis of vascular cell adhesion molecule (VCAM), a marker of inflammation which binds the integrin VLA-4 (very late activation antigen-4) expressed by monocytes and most of the lymphocytes. Focal adhesion of leukocytes to the microvasculature is a key step in inflammation and immune response. In addition, Mg deficiency upregulates IL-1\u3b1 and IL-6, pleiotropic cytokines implicated in acute phase response and inflammation (Bernardini D. et al, 2005). Because MEC are important players in inflammation and angiogenesis, I asked whether different concentrations of Mg could affect the behavior of human MEC in vitro. My results demonstrate that culture in low Mg affects human MEC with some differences in respect to HUVEC. 3)TRPM7, a Mg transport channel. The novel Mg transporter TRPM7, a ubiquitously expressed protein with the feature of being both a functional ion channel and kinase, is a critical regulator of Mg homeostasis in vascular cells. Because endothelial cells are very sensitive to extracellular concentrations of Mg, we have investigated the expression and the role of TRPM7 in human macro- and microvascular endothelial cells. I show that the regulation of TRPM7 expression is very different in human MEC vs HUVEC. By siRNA I also demonstrate completely different effects of TRPM7 silencing in HUVEC vs MEC