Cooperative Supramolecular Block Copolymerization for the Synthesis of Functional Axial Organic Heterostructures

Abstract

Supramolecular block copolymerzation with optically or electronically complementary monomers provides an attractive bottomup approach for the non-covalent synthesis of nascent axial organic heterostructures, which promises to deliver useful applications in energy conversion, optoelectronics, and catalysis. However, the synthesis of supramolecular block copolymers (BCPs) constitutes a significant challenge due to the exchange dynamics of non-covalently bound monomers and hence requires fine microstructure control. Furthermore, temporal stability of the segmented microstructure is a prerequisite to explore the applications of functional supramolecular BCPs. Herein, we report the cooperative supramolecular block copolymerization of fluorescent monomers in solution under thermodynamic control for the synthesis of axial organic heterostructures with light-harvesting properties. The fluorescent nature of the core-substituted naphthalene diimide (cNDI) monomers enables a detailed spectroscopic probing during the supramolecular block copolymerization process to unravel a nucleation−growth mechanism, similar to that of chain copolymerization for covalent block copolymers. Structured illumination microscopy (SIM) imaging of BCP chains characterizes the segmented microstructure and also allows size distribution analysis to reveal the narrow polydispersity (polydispersity index (PDI) ≈ 1.1) for the individual block segments. Spectrally resolved fluorescence microscopy on single block copolymerized organic heterostructures shows energy migration and light-harvesting across the interfaces of linearly connected segments. Molecular dynamics and metadynamics simulations provide useful mechanistic insights into the free energy of interaction between the monomers as well as into monomer exchange mechanisms and dynamics, which have a crucial impact on determining the copolymer microstructure. Our comprehensive spectroscopic, microscopic, and computational analyses provide an unambiguous structural, dynamic, and functional characterization of the supramolecular BCPs. The strategy presented here is expected to pave the way for the synthesis of multi-component organic heterostructures for various functions.

Emerging applications for living crystallization-driven self-assembly

“…221 Cooperative supramolecular block copolymerization has been achieved based on naphthalene diimide monomers with optically distinct green and red fluorescence (see Figure 5d). 235 Seeded polymerization of cyclic, hydrogen-bonded monomers has also been described, providing a remarkable, first example of a living supramolecular polymerization involving a ring-opening process. 236 Living supramolecular polymerization methods have also been used for hexabenzocoronene amphiphiles to form chiral nanotubes, including examples with segmented structures.…”

A Highly Ordered Quantum Dot Supramolecular Assembly Exhibiting Photoinduced Emission Enhancement

“…In biological systems,m ultiple biomolecules and their nanostructures with individual functions self-organize into am ulticomponent sophisticated assembly,s uch as ac ell, leading to the generation of desirable and essential functions depending on the external environment under dynamic conditions. [1][2][3] Inspired by these systems,s cientists have attempted the construction of supramolecular assemblies consisting of several different materials through social (integrative) self-sorting [4][5][6][7][8][9][10] to realize the high-performance and unexpected physical properties that are not obtained from single materials.A sf unctional nanomaterials,c olloidal semiconductor nanocrystals,r eferred to as quantum dots (QDs), have attracted much attention because of their outstanding photoluminescence (PL) properties,s uch as ah igh photodurability,s harp PL spectra and tunable energy band gap depending on the QD size. [11][12][13] Owing to the high dispersibility of QDs,m ost studies using QDs have been focused on the photophysical properties under single conditions,such as dispersed QDs in solution [14,15] and single QD levels.…”

ATP‐Driven Synthetic Supramolecular Assemblies: From ATP as a Template to Fuel

“…[98] Ther ecent interest in non-equilibrium systems suggests that the scope of wavefronts and spatiotemporal patterns of supramolecular assemblies is similar to that of natural systems.A dditionally,s ynthetic systems that can undergo ATP-driven kinetically controlled growth and/or living supramolecular polymerization can be an essential advancement to form multicomponent supramolecular block copolymers (Figure 12 g), which remains ac hallenge in supramolecular polymerization. [99] Thecareful design of monomers should lead to heterostructures with axial p-n junctions,c atalysis in tandem, as well as to supramolecular machines.T he next level in the area of ATP-driven assemblies will be the design of as ynthetic system with multicomponent self-assembly working in tandem or orthogonally for emergent functions similar to the synergistic functioning in the cellular realms (Figure 12 h). [100] This Minireview thus emphasizes the importance of ATPa sa n extraordinary tool in supramolecular chemistry for present and future developments.…”