Wydział Chemii

Sudhir Kumar Keshri

Deepak Asthana

Sonam Chorol

Yogendra Kumar

Pritam Mukhopadhyay

2018

Chemistry-A European Journal

24

1821-1832

10.1002/chem.201704604

Naukowa

Angielski

Artykuł

Three classes of donor–acceptor (D–A) π‐extended chromophores (1–12) were synthesized through a phosphite‐mediated cross‐coupling reaction, in which the anhydride‐ or imide‐based π‐As and number of tetrathiafulvalene (TTF)/dithiafulvalene (DTF) Ds were systematically changed. Large π rings, such as benzoperylene and coronene, were integrated into the TTF/DTF unit, for the first time, to overcome their high insolubility. The anhydride and imide groups in the π acceptors can significantly alter the frontier orbitals and influence the optoelectronic properties. The D moieties allow the formation of radical cations (D^.+) and the π‐extended A moieties aid the formation of radical anions (A^.−) by oxidation/reduction under ambient conditions. The molecules revealed UV/Vis/near‐IR absorption, fluorescence extending into the near‐IR region, and amphoteric electrochemical properties. Chromophores 10 and 12 show solvatochromism in a wide range of solvents. The π‐As with anhydride functionality allow easier electron uptake, relative to the imide groups, whereas the increasing number of D TTF/DTF units make them easy to oxidize. Interestingly, the trans‐TTF‐fused molecules (1, 6, and 11) exhibited a mixed‐valence state in the mid‐IR region ( =5130–4000 cm⁻¹). Moderate electron coupling between the redox centers is inferred to the compounds being of Robin–Day class II. The multistate redox activity along with panchromism and near‐/mid‐IR optical absorption of these systems can be attractive towards advanced switchable materials.

chromophores, donor–acceptor systems, mixed-valence compounds, radicals, solvatochromism

http://dx.doi.org/10.1002/chem.201704604

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