Discrete π Stack of a Tweezer‐Shaped Naphthalenediimide–Anthracene Conjugate. Issue 58 (11th September 2020)

• Record Type: Journal Article
• Authors: Keshri, Sudhir Kumar; Nakanishi, Waka; Takai, Atsuro; Ishizuka, Tomoya; Kojima, Takahiko; Takeuchi, Masayuki
• Is Part Of: Chemistry. Volume 26:Issue 58(2020)
• Page Start: 13288
• Page End: 13294
• Publication Date: 2020-09-11
• Subjects: hydrogen bonds -- molecular tweezers -- pi interactions -- stacking interactions; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202002477
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The design and synthesis of a tweezer‐shaped naphthalenediimide (NDI)–anthracene conjugate (2NDI ) are reported. In the structure of the closed form (πNDI ⋅⋅⋅ πNDI stack) of 2NDI, which was elucidated by single‐crystal XRD, the existence of C−H⋅⋅⋅ O hydrogen bonding involving the nearest carbonyl oxygen atom of an NDI unit was suggested. The tunability of πNDI ⋅⋅⋅ πNDI interactions was studied by means of UV/Vis absorption, fluorescence and NMR spectroscopy and molecular modelling. This revealed that the πNDI ⋅⋅⋅ πNDI interactions in 2NDI affect the absorption and emission properties depending on the temperature. Furthermore, in polar solvents, 2NDI prefers the stronger πNDI ⋅⋅⋅ πNDI stack, whereas the πNDI ⋅⋅⋅ πNDI interaction is diminished in nonpolar solvents. Importantly, the conformational variations of 2NDI can be reversibly switched by variation in temperature, and this suggests potential application for fluorogenic molecular switches upon temperature changes. Abstract : Tunable pi interaction : A tunable πNDI ⋅⋅⋅ πNDI interaction aided by intramolecular hydrogen bonding was found in a tweezer‐shaped naphthalenediimide (NDI)–anthracene conjugate. The πNDI ⋅⋅⋅ πNDI interaction is modulated by external stimuli such as solvent polarity and temperature variation, and this suggests potential application for fluorogenic molecular switches.