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A series of push–pull benzothiazoles were designed and synthesized by the Pd-catalyzed Sonogashira cross-coupling and [2+2] cycloaddition–retroelectrocyclization reactions. The photonic and electrochemical properties of these systems exhibit strong donor–acceptor interaction. The BTs 5 – 8 show strong intramolecular charge-transfer in the near-infrared (NIR) region. The absorption studies indicate systematic lowering of the optical HOMO–LUMO gap with increase in acceptor strength. The computational studies reveal that incorporation of strong acceptors TCNE and TCNQ results in substantial stabilization of the LUMO level compared to the HOMO level, leading to the low HOMO–LUMO gap and bathochromic shift of the absorption spectrum. The TCBD and DCNQ linked BTs 5 – 8 exhibit multi-step redox waves and improved thermal stability. [ABSTRACT FROM AUTHOR]

A set of ferrocenyl-substituted thiazoles 2 and 3 were designed and synthesized by Pd-catalyzed Sonogashira cross-coupling reaction. Their [2+2] cycloaddition–reteroelectrocyclization reaction with tetracyanoethene resulted in strong intramolecular charge transfer (ICT) chromophores 4 and 5 . The electronic absorption spectra of 4 and 5 exhibit strong ICT bands in the near infrared (NIR) region. The electrochemical studies of ferrocenyl thiazoles 4 and 5 exhibit multistep redox waves. The computational studies show good agreement with the experimental results. The incorporation of 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) unit results is improved thermal stability of ferrocenyl thiazoles. [ABSTRACT FROM AUTHOR]

Abstract: A series of donor–π–acceptor–π–donor type of ferrocenyl substituted benzothiadiazoles were designed, and synthesized by the Pd-catalyzed Sonogashira coupling reaction. The electrochemical, photophysical, thermal, and structural properties of ferrocenyl substituted benzothiadiazoles are discussed. These properties show strong donor–acceptor interaction. [Copyright &y& Elsevier]

Abstract: Donor–acceptor, perylenediimide–ferrocene conjugates have been synthesized by Suzuki, and Sonogashira coupling reactions. The photophysical and electrochemical properties of these conjugates are discussed. It has been shown that fluorescence as well as the electron affinity of the perylenediimide can be tuned by attaching the appropriate ferrocenyl derivatives. [Copyright &y& Elsevier]

A set of tetracyanoethylene (TCNE) substituted triphenylamine analogues ( 4 – 6 ) exhibiting strong intramolecular charge transfer (ICT) were designed and synthesized by the [2+2] cycloaddition–retroelectrocyclization reaction of 3 (tris-(4-phenylethynyl-phenyl)-amine) with TCNE. The reaction was found to be temperature dependent. The blue shift in the π → π ∗ transition and intramolecular charge transfer (ICT) in amines 4 – 6 were found to be directly proportional to the number of TCNE units. The computational study shows good agreement with the experimental results and reveals that as the number of TCNE units in amine increases, HOMO–LUMO gap increases. [ABSTRACT FROM AUTHOR]