Design, Synthesis and Optical Characterization of 1,8-Naphthalimide based D-pi-A System

Abstract

Design, Synthesis and Optical Characterization of 1,8-Naphthalimide based D-pi-A System

Luminescent materials find a lot of application in the field of OLEDs and bio-medical applications [1-2]. Our group has recently developed a series of 1,8-naphthilimide (NPI) based Donor-Acceptor (D-A) system [2], and we were able to fine-tune optical properties of 1,8-naphthilimide by changing donor strength judiciously. Furthermore, the PL features of 1,8-naphthilimide derivatives were sensitive to triplet oxygen, and these molecules were explored for differential imaging of hypoxia and normoxia live cancer cells. In the present study, we aim to extend the scope of available naphthalimide dyes by extending the system's conjugation by placing pi-spacer to obtain emission in near IR and utilize them for bio-imaging. In our earlier reports, the cyclic amine donors were directly connected with NPI acceptor through nitrogen on the amine moieties. In this study, we intended to connect the donor moiety via the carbon center of the amine donor moiety through a π-conjugated spacer with anticipation that the conjugated spacer may enhance the electronic conjugation length and reduce the bandgap; consequently, NIR emission may be realized. Accordingly, we designed two D-pi-A and D-pi-A-pi-D systems where donor phenothiazine is linked to accepter NPI through the vinyl pacer. The newly synthesized molecules show emission in the NIR region and the results are summerised in this thesis.

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