Tuning the donor-acceptor interactions in phase-segregated block molecules.

Brigitte A G Lamers,Anja R A Palmans,Bart W L Van Den Bersselaar,José Augusto Berrocal,Hiroshi Sato,Takuzo Aida,Kazuki Komatsu,Ghislaine Vantomme,Stefan C J Meskers,Bas F M De Waal,Martin H C Van Son,Freek V De Graaf,E W Meijer

doi:10.1039/d1mh01141c

Abstract

The assembly of donor–acceptor molecules via charge transfer (CT) interactions gives rise to highly ordered nanomaterials with appealing electronic properties. Here, we present the synthesis and bulk co-assembly of pyrene (Pyr) and naphthalenediimide (NDI) functionalized oligodimethylsiloxanes (oDMS) of discrete length. We tune the donor–acceptor interactions by connecting the pyrene and NDI to the same oligomer, forming a heterotelechelic block molecule (NDI-oDMSPyr), and to two separate oligomers, giving Pyr and NDI homotelechelic block molecules (Pyr-oDMS and NDI-oDMS). Liquid crystalline materials are obtained for binary mixtures of Pyr-oDMS and NDI-oDMS, while crystallization of the CT dimers occurred for the heterotelechelic NDI-oDMS-Pyr block molecule. The synergy between crystallization and phase-segregation coupled with the discrete length of the oDMS units allows for perfect order and sharp interfaces between the insulating siloxane and CT layers composed of crystalline CT dimers. We were able to tune the lamellar domain spacing and donor–acceptor CT interactions by applying pressures up to 6 GPa on the material, making the system promising for soft-material nanotechnologies. These results demonstrate the importance of the molecular design to tune the CT interactions and stability of a CT material.

Highlights

The alternate stacking of donor–acceptor (D–A) molecules driven by charge-transfer (CT) interactions has resulted in the New concepts donor–acceptor crystals are known for decades, the perfect arrangement is not achieved in soft materials yet due to the disorder in polymeric materials
Liquid crystalline materials are obtained for binary mixtures of Pyr-oDMS and NDI-oDMS, while crystallization of the charge transfer (CT) dimers occurred for the heterotelechelic NDI-oDMS-Pyr block molecule
We have shown that the covalent attachment of Pyr and NDI moieties by a siloxane linker in a heterotelechelic design influences the material properties and nanostructure significantly when compared to a homotelechelic, binary mixture

Summary

Introduction

The alternate stacking of donor–acceptor (D–A) molecules driven by charge-transfer (CT) interactions has resulted in the New concepts donor–acceptor crystals are known for decades, the perfect arrangement is not achieved in soft (block copolymer) materials yet due to the disorder in polymeric materials. We introduce the concept of block molecules that are in-between crystals and polymers They combine the perfect 2D crystallisation of lamellae while they still have the disordered part connecting the 2D crystalline parts. Development of various materials with fascinating electronic properties.[1,2,3,4,5] The well-known examples are the many studies by Seth Marder and his group on the use of CT interactions in functional materials. His originality in bringing new concepts to materials science has inspired many of us

Results

Discussion

Conclusion