Functionalized naphthalenediimide based supramolecular charge-transfer complexes self-assembly and their photophysical properties

• Published in: CrystEngComm 2021-03, Vol.23 (8), p.1859-1869
• Main Authors: Rani, Pooja, Husain, Ahmad, Shukla, Ananya, Singla, Neha, Srivastava, Ankit Kumar, Kumar, Gulshan, Bhasin, K. K, Kumar, Girijesh
• Format: Article
• ISSN: 1466-8033
• DOI: 10.1039/d0ce01719a

We report here the design and syntheses of a naphthalenediimide (NDI)-N functionalized organic fluorophore, 1 , and its supramolecular CT complexes [( 1 ·2H) 2+ ·(PA − ) 2 ] ( 2 ) and [( 1 ·2H) 2+ ·(3,5-DNSA − ) 2 ] ( 3 ), self-assembled from 1 as an electron acceptor (A) and picric acid (PA) or 3,5-dinitrosalicylic acid (3,5-DNSA) as a donor (D), with a very large Stokes shift (>170 nm) and significant fluorescence lifetime (∼1.55 ns). NDI is functionalized with phenylpyridyl units (chromophore) to extend the π-conjugation and thus provide a suitable platform for strong C-H---π and π π stacking interactions, which are the prime requirements for any compound to be used as a fluorescent probe. The organic fluorophore, 1 , and its supramolecular CT complexes 2 and 3 exhibit decent electronic properties as suggested by DFT, cyclic voltammetry, and fluorescence studies. Moreover, compounds 1-3 were also exploited as fluorescent probes for cell imaging under normal cell isolation and with time-bound exposure. Two new intermolecular CT complexes having large Stokes shift (>170 nm) and significant fluorescence life-time (∼1.55 ns) have been prepared and exploited for cell imaging application.