Easily-soluble heteroacene bis(benzothieno)silole derivatives for sensing of nitro explosives

Abstract

Three new heteropentacene derivatives based on bis(benzothieno)silole were synthesized. The XRD characterization reveals that the crystal structures of the heteropentacenes can be significantly influenced by the methyl substitution. The optical and electrochemical properties were investigated and the experimental results confirm that the silole motif lowers the LUMO level of the heteropentacenes. Preliminary resultsshow that the insertion of silole ring systems into rigid heteropentacenes leads to an improved solubility and high fluorescence quantum yield up to 0.74 in solution, which indicates the potential of these new silolecontaining compounds for photonic and photoelectric applications. The strong and sensitive fluorescence quenching behavior towards picric acid (PA) demonstrates that the silole-containing heteropentacene derivatives are also promising fluorescent sensor materials for detecting the nitro-containing explosives.Scheme 1 Synthesis of BBTS derivatives.

Synthesis and Characterization of Bis[1]benzothieno[3,2-b:2′,3′-d]pyrroles: Quantitative Effects of Benzannulation on Dithieno[3,2-b:2′,3′-d]pyrroles

“…Although the earliest methods involved the cyclization of 3-nitro-2,2′-dibenzo[ b ]thiophene to give the unfunctionalized BBTP 1a [ 23 ] , which could then be N -functionalized, the majority of the known synthetic methods utilize a 3,3′-dihalo-2,2′-bi(benzo[ b ]thiophene) (either 4 or 5 ) from which the central pyrrole ring is formed via catalytic amination [ 24 , 25 , 26 , 27 ]. The intermediate 4 is not only the most common route to BBTPs, but also to other benzannulated species [ 35 , 36 , 37 , 38 , 39 , 40 ] such as thieno[3,2- b :4,5- b ’]bis[1]benzothiophene [ 36 , 38 , 40 ] and phospholo[3,2- b :4,5- b ’]bis[1]benzothiophene [ 37 ].…”

Blue Electrofluorescence Properties of Furan–Silole Ladder Pi-Conjugated Systems

“…All these data are consistent with the proposed structures. Furthermore, the 29 Si and 13 C NMR shifts around the silole rings of these novel ladder furan-siloles derivatives are different from their thiophene and indole analogues [41][42][43], ( 29 Si NMR: δ (ppm) = −23.2 (indole based derivative [32]); −18.8 (Benzothiophene-based derivative [32]); −21.1 (4)) suggesting that the different aromaticity's of the O-, N-and S-fused cycles influences the electronic distribution within the fused frameworks. The crystal packing of compound 4 was investigated by X-ray diffraction (XRD) measurements.…”

“…Elemental analyses were performed by Scanmat, University of Rennes 1. Iodo-substituted benzofuran 1 was synthesized according to the published procedure [41,32]. UV-Visible spectra were recorded at room In the present article, we report on the use of blue-emitting Si,O-ladder π-conjugated systems as emitters in OLEDs showing that these systems can find applications in electroluminescent devices.…”

“…Elemental analyses were performed by Scanmat, University of Rennes 1. Iodo-substituted benzofuran 1 was synthesized according to the published procedure [32,41]. UV-Visible spectra were recorded at room temperature on a VARIAN Cary 5000 spectrophotometer (Varian, Palo Alto, CA, USA).…”

“…Elemental analyses were performed by Scanmat, University of Rennes 1. Iodo-substituted benzofuran 1 was synthesized according to the published procedure [41,32]. UV-Visible spectra were recorded at room and small 2D Polycyclic Aromatic Hydrocarbons (PAHs) [39] were also recently prepared.…”