Effects Of Structural Factors On Self - Assembly Of PDI Derivatives

Asymmetric perylene diimide(PDI) is an n-type semiconductor material and a fluorescent dye performance because of a large π bond conjugated system. Because of their special structural properties self-assembles into different morphologies. they can be used in solar cells, transfer light energy into mechanical energy, make into biological fluorescent probes, use their optical and electrical properties to make an electronic device, or use their special fluorescence properties for specific harmful gases.Nanocoiled assemblies of organic π-conjugated molecules have attracted intense attention because of their various practical applications. Herein, the assembly of highly fluorescent monolayer and bilayer nanocoils from asymmetric perylene diimide(PDI) molecules is reported. Through systematic investigation of 21 asymmetric PDI derivatives, some critical molecular structural parameters for the formation of nanocoils are formulated. Upon the combination of a methoxy substituent at the 3-position of the phenyl moiety and a methylene linker, or upon the combination of a methoxy substituent at the 2-position of the phenyl moiety and an ethylene linker in the polar side chain, PDI derivatives that bear dodecyl as the other side chain self-assemble into unique monolayer nanocoils. In contrast, the combination of two methoxy substituents at the 3,5-position of the phenyl moiety and a methylene linker or the combination of two methoxy substituents at the 2,3-position of the phenyl moiety and an ethylene linker in the polar side chain induces PDI to form bilayer nanocoils. The J-aggregate nature of the helical π-stacking geometry within the nanocoil is demonstrated by optical characterization. All of the nanocoils are highly emissive, with a fluorescence quantum yield greater than 25%. Furthermore, all of the nanocoils exhibited a NIR emission with a band maximum greater than 710 nm.This new class of highly NIR fluorescent nanostructures offers promising applications in areas such as optoelectronics, fluorescent sensors, and biological imaging.