TetrathiafulvaleneBenzothiadiazoles as Redox‐Tunable Donor–Acceptor Systems: Synthesis and Photophysical Study

Abstract

Electrochemical and photophysical analysis of new donor-acceptor systems 2 and 3, in which a benzothiadiazole (BTD) unit is covalently linked to a tetrathiafulvalene (TTF) core, have verified that the lowest excited state can be ascribed to an intramolecular-charge-transfer (ICT) π(TTF)→π*(benzothiadiazole) transition. Owing to better overlap of the HOMO and LUMO in the fused scaffold of compound 3, the intensity of the (1)ICT band is substantially higher compared to that in compound 2. The corresponding CT fluorescence is also observed in both cases. The radical cation TTF(+·) is easily observed through chemical and electrochemical oxidation by performing steady-state absorption experiments. Interestingly, compound 2 is photo-oxidized under aerobic conditions.

Self‐Assembled Architectures with Segregated Donor and Acceptor Units of a Dyad Based on a Monopyrrolo‐Annulated TTF–PTM Radical

“…Segregated stacks are ap rerequisite for obtaining conducting materials. [27][28][29][30] In addition, systemsw ith segregated TTF subunits may result in the opportunity to study the interplay in the solid state between the bistability associated with IET and intermolecular charget ransfer (ICT) phenomena typicallyrelated with stacks of neutral and/or charged TTF molecules of conducting solids.W ith this objective in mind, some of us have recently reported the D-A system 1 based on aT TF p-electron donor connected to the PTM electron acceptorb y avinylene bridge (Scheme 1). [31] This radical dyad exists in solution in equilibrium with the homo-and mixed-valence dimers under the influence of concentration, polarity of the solvent, [31,32] and temperature.…”

Triggering Emission with the Helical Turn in Thiadiazole‐Helicenes

“…Here again an intramolecular hydrogen bond (N1 ⋅⋅⋅ H4 2.27 Å) certainly contributes to the planarity of the molecule, with a dihedral angle of only 3.77° between the thiadiazole ring and the C5–C10 benzene ring (Figure b and Supporting Information, Table S4). The packing is governed by short intermolecular N ⋅⋅⋅ S distances of 3.28 Å providing dyads of 4 through formation of N 2 S 2 rings, as often observed in solid‐state structures of thiadiazole derivatives, together with aromatic π–π and CH–π interactions (Supporting Information, Figure S7).…”

Recent Developments in the Synthesis and Applications of 1,2,5-Thia- and Selenadiazoles. A Review

“…The yields of moroarylderivatives 126 were not dependent on the nature of palladium catalyst (Scheme 60). 140,[142][143][144][145] High yields of monoarylated products were obtained in the case of 2,1,3-benzothiadiazoles containing one bromine atom 127 and 128 when bis-trimethylstannane was involved in Stille reaction, 128,146 or if the reactivity of two bromine atoms differed substantially as for 4,7-dibromo [1,2,5]thiadiazolo [3,4-c]pyridine (9). 141,147,148 In the latter case, regioselective arylation occurred (Scheme 61).…”