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Novel,stimulus-responsive supramolecular structures in the formof fibers, gels, and spheres, derived from an azobenzene-containingbenzenetricarboxamide derivative, are described. Self-assembly oftris(4-((E)-phenyldiazenyl)phenyl)benzene-1,3,5-tricarboxamide(Azo-1) in aqueous organic solvent systems results insolvent dependent generation of microfibers (aq DMSO), gels (aq DMF),and hollow spheres (aq THF). The results of a single crystal X-raydiffraction analysis of Azo-1(crystallized from a mixtureof DMSO and H2O) reveal that it possesses supramolecularcolumnar packing along the baxis. Data obtainedfrom FTIR analysis and density functional theory (DFT) calculationsuggest that multiple hydrogen bonding modes exist in the Azo-1fibers. UV irradiation of the microfibers, formed in aq DMSO, causescomplete melting while regeneration of new fibers occurs upon visiblelight irradiation. In addition to this photoinduced and reversiblephase transition, the Azo-1supramolecules display areversible, fiber-to-sphere morphological transition upon exposureto pure DMSO or aq THF. The role played by amide hydrogen bonds inthe morphological changes occurring in Azo-1is demonstratedby the behavior of the analogous, ester-containing tris(4-((E)-phenyldiazenyl)phenyl)benzene-1,3,5-tricarboxylate (Azo-2) and by the hydrogen abstraction in the presence offluoride anions. [ABSTRACT FROM AUTHOR]

A new series of neutral radicals (DP1–DP6) based on diazaphenalenyl were designed via heteroatomic modifications. As spin sources, the designed radicals were implemented in four different diradical model systems (models I, II, III, and IV) by changing the reference radical and the linkage, and their magnetic interactions between the designed radicals and the reference radical were investigated by using density functional theory calculations. The trend in strength of magnetic interactions of radicals was found to be identical in different model systems. The strength of magnetic interactions could be understood by spin density distributions and NICS values. Our results will be helpful in designing and controlling the organic magnetic materials incorporated with diazaphenalenyl derivatives. In particular, as a new family of spin source radical, DP3could be a potential candidate in designing new organic magnetic materials due to its strong magnetic coupling and high stability in diradical systems. [ABSTRACT FROM AUTHOR]