Electrosynthesis uses electrons as a potent, controllable, and traceless alternative to chemical oxidants or reductants, and typically offers a more sustainable alternative to conventional redox reactions, sometimes even succeeding with better selectivity or unique reaction. Thermodynamics and kinetics at the solid-liquid interface can be accelerated by controlling potentials and current intensities, while electrochemistry can simplify purification and post-treatment processes. We focus on the electrochemical synthesis of novel organic electrical materials. A particular emphasis of our philosophy is how to understand the synthesis of electro- and photofunctional polymers from electrochemical approaches. Solid-phase electrosynthesis developed in our group can enable real-time monitoring of redox processes across a variety of length scales while producing complex polymers and materials fabrication. Recent information on our group's current research activities can be found in the group's publications, but a brief introduction to each example of recent projects is provided below.
Keywords: Solid-Phase Electrosynthesis, Iterative Synthesis, Controlled Electropolymerization, Sequence-Controlled Synthesis, Precise Synthesis; Heterometallic supramolecular polymer, Metallopolymer; Polymer Monolayer, Polymer Brush; Nonlinear Conductive Materials and Devices;
(1) Controlled Electropolymerization
Electropolymerization is one of the most important methods for synthesizing and developing conductive polymers. The complexity of the polymerization mechanism, ion doping processes, and structural defects are considered symbiotic and unavoidable, making the stagnant state and huge band gap with advanced interdisciplinary research fields and important applications in the last three decades. We have provided a perspective on controlled electropolymerization by regioselective activation reactions of monomers, where self-dimerization instead of self-electropolymerization was used. The resulting dimers play a role in the connections between functional building blocks to form functional polymers on demand.
Fig. 1 (a) Controlled electrochemical reactions based on the potential and substitution dependences. (b) Redox dimerizations of electroactive monomers are used to connect the building blocks to form functional polymers. (c) Precise synthesis is conducted by alternative redox reactions via switching positive and negative potentials. Current Opinion in Electrochemistry 2022, 33, 100952. invited review
(2) Solid-Phase Electrosynthesis (Electrochemical Iterative Synthesis, Precise Synthesis)
We developed the electrochemical iterative synthesis of a monomer A-B through individual A–A or B–B coupling driven by electrochemical switching of positive and negative bias on a self-assembled A or B electrode.
Fig. 2 Solid-phase electrosynthesis. Acc. Chem. Res. 2023, in press.
Richly stimulated organometallic polymers are considered candidates for ultra-high information storage and anti-counterfeiting security. However, their controllable synthesis has been an unsolved challenge. We have reported the rapid sequence-controlled electrosynthesis of organometallic polymers with the exquisite insertion of multiple and distinct monomers.
Fig. 3 Rapidly sequence-controlled electrosynthesis. Nat. Commun. 2020, 11, 2530.
(3) Sequence-Controlled Conductance and Memristive Functions of Metallopolymer Monolayers
Understanding how charge travels through sequence-controlled molecules has been a formidable challenge due to simultaneous requirements in well-controlled synthesis and well-manipulated orientation. We report electrically driven simultaneous synthesis and crystallization as a general strategy to study the conductance of composition and sequence-controlled unioligomer and unipolymer monolayers. Our work demonstrates a promising way to release an ultra-rich variety of electrical parameters and optimize the functions and performances of multilevel resistive devices.
Fig. 4 Composition and sequence-controlled conductance of crystalline unimolecular monolayers. Sci. Adv. 2023, 9, eadh0667.
(4) Unidirectional Orientated Non-crystalline Metallopolymers
Long-range ordered nanoarchitecture of polymers is hampered by kinetic and statistical restrictions during polymer synthesis and manipulation. We have reported the monolayer nanoarchitecture of long-range crystalline metallopolymers via kinetically accelerated and statistically allowed iterative growth, guided by a self- assembled monolayer with monitoring and defect-repair abilities.
Fig. 5 Monolayer nanoarchitecture of crystalline metallopolymers by electrochemical iterative growth. Cell Rep. Phys. Sci. 2022, 3, 100852.
Repairable electrosynthesis, combined with the advantages of simultaneous artificial synthesis and manipulation, is a powerful method for fabricating monolayers of unidirectional crystalline functional polymers with sophisticated molecular structures that are very difficult to crystallize. The scalable and programmable electrosynthesis also provides an opportunity to challenge the preparation of an isolated ultra-long polymer and the synthetically iterative limit for further fundamental study.
Fig. 6 Monolayer nanoarchitecture and single polymer chain of metallopolymers prepared by electrochemical iterative growth. Angew. Chem. Int. Ed. 2023, DOI: 10.1002/anie.202216838.hot paper
Fig. 7 Nanoarchitectonics on electrosynthesis and assembly of conjugated metallopolymers. Angew. Chem. Int. Ed. 2023, DOI: 10.1002/ange.202311778. hot paper