Charge‐Transfer‐Complexed Conjugated Microporous Polymers (CT‐CMPs)

Abstract

oligomeric backbone. [12] The conjugated materials showed strong color changes (indicating CT-complex formation) from bright orange to deep green upon mechanical grinding in the solid state at room temperature. This color change was easily reversible by sonication in toluene. However, after dissolution of the material the ability to readily form a CT complex was lost. To overcome this, we chemically bonded the CT complexes to a semicrystalline cellulose template following previous work on the use of CT complexes for medical imaging. [13] The modular structure of CT complexes, along with the dependence of their properties on spatial and environmental factors, allows control over the crystal structure and optical properties by alternating the CT interaction between electron donors and electron acceptors. However, elucidating the necessary parameters for efficient CT complexation of polymers with small molecules remains challenging. Herein, we focus on 3D porous motifs in the electron donor-type conjugated microporous polymers (CMPs). [14][15][16][17][18][19] To disrupt the π-π stacking of the linear polymer, aromatic building blocks that have a near 90° kink were used. Construction of 3D pores in this manner have already been reported using, for example, 9,9′-spirobifluorene, [20,21] triptycene, [22,23] and tetraphenylmethane. [24][25][26] Incorporating such kinds of monomers into the polymer backbone was expected to prevent the stiff polymer chains from space efficient packing. This would enhance the stability and doping rate of CT complex formation from the simple mixture between the CMP and various acceptors at room temperature thanks to the suppression of π-π stacking interactions and higher free surface area. CT interactions have been studied in porous polymers before, for instance in the field of covalent organic frameworks. [27] The work presented here, however, is among the first reports of CTcomplexed CMPs. This combination introduces more electron mobility in the conjugated polymer network, making this concept very interesting for organic electronics.Here we report the design and synthesis of electron-donating CMPs consisting of alternating spirobifluorene (SBF-Br) and pyrene (diboronic acid bis(pinacol) ester (Py-Bpin)) units. The CMP permits inherent ordering of conjugated chains in all three dimensions, and displays a striking combination: thermal stability and nonextended π-delocalization in the solid state as compared with the linear conjugated polymer. We then demonstrate the rapid preparation of a chemically and thermally stable 3D CT-complexed CMP with a high surface area. A new concept of the formation of charge transfer (CT) complexes between an intrinsically electron-donating conjugated microporous polymer and a small molecule acceptor is reported. Spirobifluorenebased mesoporous organic polymers with high porosity and Brunauer-Emmett-Teller surface area are synthesized by the Suzuki-coupling reaction of spirobifluorene and pyrene monomers. The simple doping of the synthesized mesoporous, elect...

π-Face strapped monomers enable self-stabilized hyperbranched π-conjugated polymer particles

“…The higher surface area to volume ratio of HB-PAMs resulting from the pancake morphology is advantageous for effective interaction with small molecule dopants for electronic and semiconducting applications. 41,68,69…”

“…The higher surface area to volume ratio of HB-PAMs resulting from the pancake morphology is advantageous for effective interaction with small molecule dopants for electronic and semiconducting applications. 41,68,69 The UV-vis absorption and photoluminescence spectra of p-PAM, m-PAM and HB-PAM-1 in CHCl 3 are shown in Fig. 6 and their optical properties are summarized in Table 5.…”

An Appraisal for Providing Charge Transfer (CT) Through Synthetic Porous Frameworks for their Semiconductor Applications

“…[1] It is necessary to evaluate the state of recently developed synthetic porous materials after ten years of development, which can be employed for a variety of CT applications, particularly in semiconductors. These porous organic frameworks can be classified based on various chemical conjugations, including 𝜋-conjugated microporous polymers (CMPs), [2] covalently-bonded organic frameworks (covalent organic frameworks: COFs), [3] and metal coordination-bonded organic frameworks (metal-organic frameworks: MOFs). [4] These synthetic porous materials with numerous combinations of organic building blocks possess unique properties, advantages, and disadvantages.…”

Using molecular straps to engineer conjugated porous polymer growth, chemical doping, and conductivity

“…[16][17][18][19][20] For example, CPPs provide a porous and morphologically stable architecture for acceptors to interact with the polymer and facilitate charge transfer. [21][22][23][24] 3D-network architectures provide quick and efficient pathways to move charges and energy within the network. 25,26 Also, the rate of doping and stability of the charge transfer complex are higher for CPPs than the linear polymers because of the suppression of p-p stacking interactions and higher free surface area.…”

“…25,26 Also, the rate of doping and stability of the charge transfer complex are higher for CPPs than the linear polymers because of the suppression of p-p stacking interactions and higher free surface area. 23,24 Despite these interesting features, CPPs are relatively underexplored for energy harvesting applications due to poor processability and lower electrical conductivities. 1,4,27 Systematic studies focused towards understanding the effect of the CPP structure and network architecture on doping efficiency and conductivity are essential to explore and harness the advantages of the CPPs porous architecture for energy harvesting applications.…”