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Exquisite 1D Assemblies Arising from Rationally Designed Asymmetric Donor–Acceptor Architectures Exhibiting Aggregation‐Induced Emission as a Function of Auxiliary Acceptor Strength
Author(s) -
Singh Roop Shikha,
Mukhopadhyay Sujay,
Biswas Arnab,
Pandey Daya Shankar
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201503570
Subject(s) - malononitrile , intramolecular force , acceptor , intermolecular force , quenching (fluorescence) , piperazine , chemistry , electron acceptor , electrochemistry , topology (electrical circuits) , nanotechnology , photochemistry , materials science , stereochemistry , molecule , organic chemistry , mathematics , fluorescence , physics , electrode , combinatorics , condensed matter physics , catalysis , quantum mechanics
One‐dimensional nanostructures with aggregation‐induced emission (AIE) properties have been fabricated to keep the pace with growing demand from optoelectronics applications. The compounds 2‐[4‐(4‐methylpiperazin‐1‐yl)benzylidene]malononitrile ( PM1 ), 2‐{4‐[4‐(pyridin‐2‐yl)piperazin‐1‐yl]‐benzylidene}malononitrile ( PM2 ), and 2‐{4‐[4‐(pyrimidin‐2‐yl)piperazin‐1‐yl]benzylidene}malononitrile ( PM3 ) have been designed and synthesized by melding piperazine and dicyanovinylene to investigate AIE in an asymmetric donor–acceptor (D–A) construct of A′–D–π–A‐ topology. The synthetic route has been simplified by using phenylpiperazine as a weak donor (D), dicyanovinylene as an acceptor (A), and pyridyl/pyrimidyl groups ( PM2/PM3 ) as auxiliary acceptors (A′). It has been established that A′ plays a vital role in triggering AIE in these compounds because the same D–A construct led to aggregation‐caused quenching upon replacing A′ with an electron‐donating ethyl group ( PM1 ). Moreover, the effect of restricted intramolecular rotation and twisted intramolecular charge transfer on the mechanism of AIE has also been investigated. Furthermore, it has been clearly shown that the optical disparities of these A′–D–π–A architectures are a direct consequence of comparative A′ strength. Single‐crystal X‐ray analyses provided justification for role of intermolecular interactions in aggregate morphology. Electrochemical and theoretical studies affirmed the effect of the A′ strength on the overall properties of the A′–D–π–A system.