Controlled n‐Doping of Naphthalene‐Diimide‐Based 2D Polymers

Abstract

Abstract2D polymers (2DPs) are promising as structurally well‐defined, permanently porous, organic semiconductors. However, 2DPs are nearly always isolated as closed shell organic species with limited charge carriers, which leads to low bulk conductivities. Here, the bulk conductivity of two naphthalene diimide (NDI)‐containing 2DP semiconductors is enhanced by controllably n‐doping the NDI units using cobaltocene (CoCp2). Optical and transient microwave spectroscopy reveal that both as‐prepared NDI‐containing 2DPs are semiconducting with sub‐2 eV optical bandgaps and photoexcited charge‐carrier lifetimes of tens of nanoseconds. Following reduction with CoCp2, both 2DPs largely retain their periodic structures and exhibit optical and electron‐spin resonance spectroscopic features consistent with the presence of NDI‐radical anions. While the native NDI‐based 2DPs are electronically insulating, maximum bulk conductivities of >10−4 S cm−1 are achieved by substoichiometric levels of n‐doping. Density functional theory calculations show that the strongest electronic couplings in these 2DPs exist in the out‐of‐plane (π‐stacking) crystallographic directions, which indicates that cross‐plane electronic transport through NDI stacks is primarily responsible for the observed electronic conductivity. Taken together, the controlled molecular doping is a useful approach to access structurally well‐defined, paramagnetic, 2DP n‐type semiconductors with measurable bulk electronic conductivities of interest for electronic or spintronic devices.

Electronic Spin Qubit Candidates Arrayed within Layered Two-Dimensional Polymers

“…Electronic spin centers were introduced into diamagnetic TAPPy-NDI by chemically reducing NDI to its paramagnetic anion (NDI •− ). This reduction is achieved by introducing cobaltocene (CoCp 2 , −1.3 V vs Fc/Fc + ) to the 2DP, which gives rise to relatively homogenous doping 39 without disrupting the chemical integrity or structural regularity of the network at high doping levels, as revealed by PXRD and FT-IR spectroscopy (Figure 2A,C). The PXRD pattern upon full reduction (1.0 equiv of CoCp 2 ) exhibits several sharp higher-order diffraction peaks and is slightly changed from that of the unreduced 2DP, indicating that the lattice remains intact upon doping.…”

π-Stacks of radical-anionic naphthalenediimides in a metal-organic framework

“…Naphthalenediimides (NDIs) are π-electron-deficient polycyclic aromatic compounds that undergo one-and two-electron reductions to their radical anions (NDI •− ) and dianions (NDI 2− ) (1,2). The distinct optical, electronic, and magnetic properties of NDIs and their anions enable their wide applications in sensors, organic electronics, n-type semiconductors, photoelectrical devices, photothermal therapy, and catalysts (3)(4)(5)(6)(7)(8)(9)(10)(11). Despite the delocalization of its unpaired electron in the planar π-conjugated system, NDI •− is susceptible to oxidative and collisional or aggregation-induced radical state quenching (9,12,13); this inherent lability limits its practical use.…”

Covalent organic framework linked with amination luminol derivative as enhanced ECL luminophore for ultrasensitive analysis of cytochromec

“…Covalent organic frameworks (COFs) are an emerging type of crystalline porous polymer (constructed using organic building blocks via robust covalent bonds), 24,25 which hold superior potential in gas storage, catalysis, and optoelectronics for their fascinating features ( e.g. , tunable pore size and large specific surface area).…”

“…Covalent organic frameworks (COFs) are an emerging type of crystalline porous polymer (constructed using organic building blocks via robust covalent bonds), 24,25 which hold superior potential in gas storage, catalysis, and optoelectronics for their fascinating features (e.g., tunable pore size and large specic surface area). 26 Unlike MOFs, COFs show observable resistance in extremely acidic or alkaline environment, which combats issues of aqueous instability and difficulty to surface functionalize.…”