Fluorescence Color Modulation by Intramolecular and Intermolecular π−π Interactions in a Helical Zinc(II) Complex

Abstract

When a fluorescent compound shows unique optical properties, an elucidation of the mechanism may lead to an important development of novel sensing strategies. A helical 3,3′-di-tert-butylsalen-zinc(II) complex, [Zn 2 L 1 2 ], has a red-shifted fluorescence as compared to that of [ZnL 2 2 ], a half-structured mononuclear complex of [Zn 2 L 1 2 ]; in addition, [Zn 2 L 1 2 ] exhibits a fluorescence color change from green to light blue under external stimulations. We investigated the origins of these phenomena by spectroscopy, fluorescence lifetime measurement, fluorescence microscopy, X-ray powder diffraction, and X-ray singlecrystal analysis. From the experimental data, we concluded that intramolecular and intermolecular π-π interactions are critical elements that determine the shifts of the fluorescence to a longer wavelength.

Synthesis and Mechanofluorochromism of 4-[Bis(4-methylphenyl)amino]acetophenone

“…Among them, materials that exhibit reversible change in fluorescent color induced by mechanical stress such as grinding, namely "mechanofluorochromism", have recently been received attention. Several examples of both organometallic and pure organic materials have been reported to exhibit mechanofluorochromism [1][2][3][4][5][6][7][8][9][10][11][12][13] and these phenomena were generally believed to be due to change in intermolecular interactions caused by altering the molecular arrangements in the crystalline state by mechanical stress.…”

Synthesis, structure, optoelectronic properties of novel zinc Schiff-base complexes

“…Chemical modifications of the ligand, e.g., introduction of some functional groups or substitution of some parts with appropriate ones often changes molecular structures and properties drastically. For example, introduction of butyl group into the positions adjacent to the hydroxyl groups of Schiff-base leads to a formation of four-coordinated complex [18,19]. However, there have been few reports about the crystal structure of zinc Schiffbase complexes used as electroluminescent materials.…”

Supramolecular Template‐Directed Synthesis of Perfect Phenelenediimino‐Bridged Ladderlike Polyphenylsiloxanes

“…By contrast, the fluorescence profile of the superstructure LS sample in high-wavelength region suggests that there are the intramolecular interactions in solutions of the monomer, namely, hydrogen-bonding and p-p interactions. [22][23][24] DSC measurement of PLPS: Compared with the lower T g for the single-chain polysiloxane (e.g., T g = À69.4 8C for polyphenylmethylsiloxane [25] ), the much higher Tg for the PLPS (T g = 176.4 8C) indicates higher stiffness, which arises from fact that the internal rotation of the -Si-O-Si-main chain are greatly restricted. If PLPS possesses some branched structure its T g should be greatly decreased.…”