Metal-ion permeation in congested nanochannels: the exposure effect of Ag plus ions on the phosphorescent properties of a gold(I)-pyrazolate complex that is confined in the nanoscopic channels of mesoporous silica

An organometallic/silica nanocomposite of a 1D cylindrical assembly of a trinuclear gold(I)pyrazolate complex ([Au3Pz3]) that was confined inside the nanoscopic channels of hexagonal mesoporous silica ([Au3Pz3]/silicahex), emitted red light with a luminescence center at 693 nm upon photoexcitation at 276 nm owing to a AuI?AuI metallophilic interaction. When a film of [Au3Pz3]/silicahex was dipped into a solution of Ag+ in tetrahydrofuran (THF), the resulting nanocomposite material (Ag@[Au3Pz3]/silicahex) emitted green light with a new luminescence center at 486 nm, which was characteristic of a AuI?AgI heterometallic interaction. Changes in the emission/excitation and XPS spectra of Ag@[Au3Pz3]/silicahex revealed that Ag+ ions permeated into the congested nanochannels of [Au3Pz3]/silicahex, which were filled with the cylindrical assembly of [Au3Pz3]

Effect of acidic aqueous alcohol solution on template sol-gel synthesis of phosphorescent hexagonal mesoporous silica film nanocomposite

Here novel mesoporous silica film nanocomposite with a hexagonal structure is successfully synthesized by using phosphorescent columnar assembly of a trinuclear gold(I) pyrazolate complex bearing amphiphilic side chains [Au3Pz3], formed via a weak Au^Au1 metallophilic interaction, as a functional template in the sol-gel synthesis. By controlling the molar ratios of alcohol to acid in an acidic aqueous alcohol solution, the sol-gel synthesis of columnar assembled [Au3Pz3] with a silica source can provide highly ordered hexagonal mesoporous silica film composite [Au3Pz3]/silicahex consisting one-dimensional molecular assembly in the nanoscopic channels. The as-fabricated silica film nanocomposite [Au3Pz3]/silicahex with red emission have phosphorescent properties with luminescence emission centered at 693nm (λext=276nm; Stokes shift, Δλ=417nm) and lifetime at 7.8jus (λext=266nm, λem=690nm)

Simulating Assembly Landscapes for Comprehensive Understanding of Supramolecular Polymer-Solvent Systems

Complexity in supramolecular polymer systems arises from interactions between different components, including solvent molecules. By varying their concentration or temperature in such multicomponent systems, complex phenomena can occur such as thermally bisignate and dilution-induced assembly of supramolecular polymers. Herein, we demonstrate that both these phenomena emerge from the same underlying interaction mechanism between the components. As a model system, amide-decorated supramolecular polymers of porphyrins were investigated in combination with aliphatic alcohols as hydrogen-bond scavengers, and thermodynamic mass-balance models were applied to map the three-dimensional assembly landscapes. These studies unveiled that the interaction between hydrogen-bond scavengers and monomers is temperature-dependent and becomes dominant at high monomer concentrations. With these insights, we could exploit competitive monomer-alcohol interactions to prompt the dilution-induced assembly of various common monomers as well as bisignate assembly events. Moreover, kinetic insights were obtained by navigating through the assembly landscape. Similar to phase diagrams of covalent polymers, these assembly landscapes provide a comprehensive picture of supramolecular polymerizations, which helps to precisely regulate the system properties. The generality of this approach using assembly landscapes makes it relevant for any supramolecular system, and this enhanced control will open the door to build complex and functional supramolecular polymer systems.</p

Molecularly Engineered “Janus GroEL”: Application to Supramolecular Copolymerization with a Higher Level of Sequence Control

Herein we report the synthesis and isolation of a shape-persistent Janus protein nanoparticle derived from the biomolecular machine chaperonin GroEL (^AGroEL^B) and its application to DNA-mediated ternary supramolecular copolymerization. To synthesize ^AGroEL^B with two different DNA strands A and B at its opposite apical domains, we utilized the unique biological property of GroEL, i.e., Mg²⁺/ATP-mediated ring exchange between ^AGroEL^A and ^BGroEL^B with their hollow cylindrical double-decker architectures. This exchange event was reported more than 24 years ago but has never been utilized for molecular engineering of GroEL. We leveraged DNA nanotechnology to purely isolate Janus ^AGroEL^B and succeeded in its precision ternary supramolecular copolymerization with two DNA comonomers, A** and B*, that are partially complementary to A and B in ^AGroEL^B, respectively, and programmed to self-dimerize on the other side. Transmission electron microscopy allowed us to confirm the formation of the expected dual-periodic copolymer sequence −(^(B*/B)GroEL^(A/A**/A**/A)GroEL^(B/B*))– in the form of a laterally connected lamellar assembly rather than a single-chain copolymer

Supramolecular polymers – we've come full circle

Since the first polymers were discovered, scientists have debated their structures. Before Hermann Staudinger published the brilliant concept of macromolecules, polymer properties were generally believed to be based on the colloidal aggregation of small particles or molecules. From 1920 onwards, polymers and macromolecules are synonymous with each other; i. e. materials made by many covalent bonds connecting monomers in 2 or 3 dimensions. Although supramolecular interactions between macromolecular chains are evidently important, e. g. in nylons, it was unheard of to proposing polymeric materials based on the interaction of small molecules. Breakthroughs in supramolecular chemistry, however, showed that polymer materials can be made by small molecules using strong directional secondary interactions; the field of supramolecular polymers emerged. In a way, we have come full circle. In this essay we give a personal story about the birth of supramolecular polymers, with special emphasis on their structures, way of formation, and the dynamic nature of their bonding. The adaptivity of supramolecular polymers has become a major asset for novel applications, e. g. in the direction for the sustainable use of polymers, but also in biomedicine and electronics as well as self-healing materials. The lessons learned in the past years include aspects that forecast a bright future for the use of supramolecular interactions in polymer materials in general and for supramolecular polymers in particular. In order to give full tribute to Staudinger in the year celebrating 100 years of macromolecules, we will show that many of the concepts of macromolecular polymers apply to supramolecular polymers, with only one important difference with fascinating consequences: the dynamic nature of the bonds that form polymer chains