Enhanced Conductivity for Carbon Nanotube Based Materials through Supramolecular Hierarchical Self‐Assembly

Abstract

their hierarchical control at multiple scales [2] (e.g., nanoscale, microscale, meso scale, and macroscale) and costeffective ness of the raw materials [3] together with simple and scalable processing steps. In this sense, the hierarchical selfassembly of molecular, macromolecular, or nano structured building blocks (BBs) via supra molecular interactions has emerged as a promising strategy that allows for sponta neous control of matter at different scales. Hierarchically organized systems have found many uses including recognition elements in theranostic tools, [4] stimuli responsive parts in soft materials, [5] trans ducers and mesoporous components in chemical sensors, [6] hybrid bioorgano metallic assemblies in optical switches, [7] multilayer topologies in energy conver sion/storage systems, [8] and patterned con ductors [9] in electronic devices.However, transparent electrically con ducting components in optoelectronic systems still depend on metal oxide tech nologies (rather than hierarchical self assembly designs) where indiumtin oxide (ITO) has played a leading role for several decades. [10] Most of the recently explored alternatives in transparent con ductors include lowdimensional metaloxide or carbonbased electrically conducting nanostructures such as nanoparticles, nanowires, nanorods, and nanosheets. [11] Unfortunately, the development of those alternatives by precisely controlling these The currently limited comprehension of hierarchical control over outof-equilibrium (dynamic) self-assembly processes in nanoscience and nanotechnology has limited the exploitation of multicomponent systems in the design of new nanostructured functional materials. In this study's contribution, molecular building blocks with tailored nanoscale anisotropic supramolecular self-assembly behavior enable the creation of mesoscale percolation networks of multiwalled carbon nanotubes through collinear interconnections at the microscale. This strategy affords polymeric composites with tunable properties at the macroscale, where the organization mechanism is regulated by dynamic self-assembly at 4 hierarchical levels of auto-organization. Such multilevel selfassembly system reduces up to eightfolds the nanotube concentration required for percolation and enhances conductivity up to 6 orders of magnitude against blanks, thus yielding anisotropically semiconducting and conducting materials. The approach is based on casting-from-solution, thus simplifying preparative steps when compared to state-of-the-art electron carrier counterparts such as single-walled carbon nanotube-, graphene-, or indium-tin-oxide-based technologies. Finally, promising material transparency levels can be reached across the visible and near-infrared regimes for compositions above the percolation threshold, which provides new opportunities beyond the current spectral restrictions in commercial transparent conductors.

On the Aggregation and Sensing Properties of Zinc(II) Schiff-Base Complexes of Salen-Type Ligands

“…Therefore, it turns out that in absence of Lewis bases these complexes are generally stabilized through intermolecular Zn⋯O axial interactions involving the phenolic oxygen atoms of the ligand framework, leading to penta-coordinated square-pyramidal Zn(II) geometries [15]. Unless there is a sterical hindrance by bulky substituents in the salicylidene rings [25], or the Zn(II) metalation involves shape persistent L macrocycles [26], the mutual Zn⋯O interaction leads to the formation of dimers [27,28,29,30,31], while larger oligomeric aggregates, including mesomorphic [32,33,34,35] and nanostructured [36,37,38,39,40,41,42,43,44,45,46] species are obtained in the other cases. On the other hand, in the presence of monotopic Lewis bases ZnL complexes form monomeric adducts [28,30,47,48,49,50,51,52] with the base axially coordinated to the metal (Scheme 1).…”

Synthesis of a Novel Zn-Salphen Building Block and Its Acrylic Terpolymer Counterparts as Tunable Supramolecular Recognition Systems

“…These tailored characteristics were further translated into the anisotropic self-assembly control of networked nanostructures in a polymer matrix that mimicked the neurons in a brain. Furthermore, we very recently exploited that same approach to develop hierarchically self-assembled polymer composite nanomaterials with promising optoelectronic applications [28].…”

A Constrained and “Inverted” [3+3] Salphen Macrocycle with an ortho‐Phenylethynyl Substitution Pattern

“…Salphens are p-conjugated salen systemsa nd thus have advantages in terms of stability, optical properties, and reactivity, which, for instance, make them excellent catalysts and ion sen-sors. [18,[22][23][24] The reversible character of imine condensation with dynamic exchange of C=Nb onds meets the requirements for dynamic covalentr eactions, [25] which has been exploited to prepare shape-persistent 2D and 3D molecular systems of highc omplexity in high yields, such as macrocycles [26][27][28][29][30] tiered architectures, [31] capsules, [32] and molecular cages. [16][17][18] Salphen-type macrocycles have attractedaparticular interesti nt he field of supramolecular chemistry,o wing to their ability to self-assemble into organized stacks.…”

“…[7][8][9][10][19][20][21] In particular,t he aggregation behavior of multinuclear Zn II salphen complexes is strongly enhanced owing to their unusual oligomeric (ZnÀO) n coordination motifs, ap eculiar property that has been exploited for the construction of self-assembled nanostructures of very high stability. [18,[22][23][24] The reversible character of imine condensation with dynamic exchange of C=Nb onds meets the requirements for dynamic covalentr eactions, [25] which has been exploited to prepare shape-persistent 2D and 3D molecular systems of highc omplexity in high yields, such as macrocycles [26][27][28][29][30] tiered architectures, [31] capsules, [32] and molecular cages. [33][34][35][36][37][38] Oneo ft he main synthetic challenges is to obtain selectively one type of macrocycle of ag iven size in good yield.…”