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The Design of Radical Stacks: Nitronyl-Nitroxide-Substituted Heteropentacenes.

ABSTRACT: The first alkyl chain-anchored heteropentacene, dithieno[2,3-d;2',3'-d']benzo-[1,2-b;3,4-b']dithiophene (DTmBDT), mono- or disubstituted with a nitronyl nitroxide group has been prepared through a cross-coupling synthetic procedure of the corresponding dibromo-derivative (Br₂-DTmBDT) with a nitronyl nitroxide-2-ide gold(I) complex. The synthesized nitroxides possess high kinetic stability, which allowed us to investigate their structure and thermal, optical, electrochemical, and magnetic properties. Single-crystal X-ray diffraction of both mono- and diradicals revealed that the nitronyl nitroxide group lies almost in the same plane as the nearest side thiophene ring. Such arrangement favors formation of edge-to-edge dimers, which then form close π-stacks surrounded by interdigitating alkyl chains. Before melting, these nitronyl nitroxide radical substituted molecules undergo at least two different phase transitions (PTs): for the monoradical, PTs are reversible, accompanied by hysteresis, and occur near 13 and 83 °C; the diradical upon heating shows a reversible PT with hysteresis in the temperature range 2-11 °C and an irreversible PT near 135 °C. PTs of this type are absent in Br₂-DTmBDT. Therefore, the step-by-step substitution of bromine atoms by nitronyl nitroxide groups changes the structural organization of DTmBDT and induces the emergence of PTs. This knowledge may facilitate crystal engineering of π-stacked paramagnets and related molecular spin devices.

SUBMITTER: Tretyakov E

PROVIDER: S-EPMC5641907 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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The Design of Radical Stacks: Nitronyl-Nitroxide-Substituted Heteropentacenes.

Tretyakov Evgeny E Keerthi Ashok A Baumgarten Martin M Veber Sergey S Fedin Matvey M Gorbunov Dmitry D Shundrina Inna I Gritsan Nina N

ChemistryOpen 20170830 5

The first alkyl chain-anchored heteropentacene, dithieno[2,3-d;2',3'-d']benzo-[1,2-b;3,4-b']dithiophene (DTmBDT), mono- or disubstituted with a nitronyl nitroxide group has been prepared through a cross-coupling synthetic procedure of the corresponding dibromo-derivative (Br2-DTmBDT) with a nitronyl nitroxide-2-ide gold(I) complex. The synthesized nitroxides possess high kinetic stability, which allowed us to investigate their structure and th ...[more]

PMID: 29046859

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Dataset Information

The Design of Radical Stacks: Nitronyl-Nitroxide-Substituted Heteropentacenes.

Publications

The Design of Radical Stacks: Nitronyl-Nitroxide-Substituted Heteropentacenes.

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