Assessing the Impact of π‐Conjugation Length on Aggregation Induced Emission and Self‐Assembly Formation of α‐Cyanostilbene and Bis‐Cyanostilbene

In this work, short π‐conjugated (Z)‐2‐(4‐(2‐cyano‐2‐phenylvinyl)phenoxy)‐N‐(1‐(3‐ethoxy‐4‐methoxyphenyl)‐2‐(methyl sulfonyl)ethyl)acetamide (CYS) and large π‐conjugated 2,2′‐(((1Z,1′Z)‐1,4‐phenylenebis(2‐cyanoethene‐2,1‐diyl))bis(4,1‐phenyl ene))bis(oxy))bis(N‐(1‐(3‐ethoxy‐4‐methoxyphenyl)‐2‐(methyl sulfonyl)ethyl)acetamide (BCYS) compounds were synthesized. Furthermore, the influence of π‐conjugation length on CYS and BCYS absorption, fluorescence, aggregation induced emission (AIE) characteristics, and self‐assembly was examined. The large π‐conjugated BCYS (π‐conjugation length=18.71 Å) exhibits AIE property getting on in the DMSO−Water solvent combination as the volume % of water increases and demonstrated production of self‐assembled bundle of micro fibrous structure of around 5 to 6 microns long and 200 to 500 nm wide. Short π‐conjugated CYS (π‐conjugation length=10.80 Å), on the other hand, exhibits aggregation caused quenching (ACQ) in the DMSO−Water solvent combination as the volume % of water increases and the creation of self‐assembled nanostructured crystalline asymmetrical particles. Moreover, the cytotoxicity study of CYS and BCYS revealed that BCYS had superior biocompatibility than CYS. This study design and synthesizes short π‐conjugated α‐cyanostilbene CYS (10.80 Å) and large π‐conjugated Bis‐cyanostilbene BCYS (18.71 Å). As the volume % of water in DMSO increases, the CYS exhibits the ACQ phenomenon and self‐assembles into nano particles. In contrast, BCYS exhibits the AIE phenomena and self‐assembly of a micro‐fibrous structure. Cytotoxicity investigation showed that BCYS is more biocompatible than CYS.