The development of electronic devices at the single-molecule scale requires detailed understanding of charge transport through individual molecular wires. To characterize the electrical conductance, it is necessary to vary the length of a single molecular wire, contacted to two electrodes, in a controlled way. Such studies usually determine the conductance of a certain molecular species with one specific length. We measure the conductance and mechanical characteristics of a single polyfluorene wire by pulling it up from a Au(111) surface with the tip of a scanning tunneling microscope, thus continuously changing its length up to more than 20 nanometers. The conductance curves show not only an exponential decay but also characteristic oscillations as one molecular unit after another is detached from the surface during stretching.

The site-specific incorporation of noncanonical monomers into polypeptides through genetic code reprogramming permits synthesis of bio-based products that extend beyond natural limits. To better enable such efforts, flexizymes (transfer RNA (tRNA) synthetase-like ribozymes that recognize synthetic leaving groups) have been used to expand the scope of chemical substrates for ribosome-directed polymerization. The development of design rules for flexizyme-catalyzed acylation should allow scalable and rational expansion of genetic code reprogramming. Here we report the systematic synthesis of 37 substrates based on 4 chemically diverse scaffolds (phenylalanine, benzoic acid, heteroaromatic, and aliphatic monomers) with different electronic and steric factors. Of these substrates, 32 were acylated onto tRNA and incorporated into peptides by in vitro translation. Based on the design rules derived from this expanded alphabet, we successfully predicted the acylation of 6 additional monomers that could uniquely be incorporated into peptides and direct N-terminal incorporation of an aldehyde group for orthogonal bioconjugation reactions.

Totally wired: A particular molecular adsorption geometry can be prepared by adsorbing single conjugated polyfluorene chains partially on a clean Au(111) surface and partially on a thin crystalline NaCl film, thus connecting metallic and insulating surface areas. This configuration allows the electronic characterization of one and the same molecular wire as a function of its atomic-scale environment in a planar configuration

In coordination-driven self-assembly, 2,2′:6′,2″-terpyridine (tpy) has gained extensive attention in constructing supramolecular architectures on the basis of ⟨tpy-M-tpy⟩ connectivity. In direct self-assembly of large discrete structures, however, the metal ions were mainly limited to Cd­(II), Zn­(II), and Fe­(II) ions. Herein, we significantly broaden the spectrum of metal ions with seven divalent transition metal ions M­(II) (M = Mn, Fe, Co, Ni, Cu, Zn, Cd) to assemble a series of supramolecular fractals. In particular, Mn­(II), Co­(II), Ni­(II), and Cu­(II) were reported for the first time to form such large and discrete structures with ⟨tpy-M-tpy⟩ connectivity. In addition, the structural stabilities of those supramolecules in the gas phase and the kinetics of the ligand exchange process in solution were investigated using mass spectrometry. Such a fundamental study gave the relative order of structural stability in the gas phase and revealed the inertness of coordination in solution depending on the metal ions. Those results would guide the future study in tpy-based supramolecular chemistry in terms of self-assembly, characterization, property, and application.

This report presents the synthesis of a tetraphenyladamantane-based microporous polycyanurate network with a BET surface area of 843 m(2) g(-1) and a pore size of 7.8 Å. It uptakes 98.0 wt% benzene (298 K, P/P0 = 0.9), 1.49 wt% H2 (77 K/1 bar) and 12.8 wt% CO2 (273 K/1 bar) with CO2/N2 selectivity of up to 112.

Robust molecule–metal linkages are essential for developing high-performance and air-stable devices for molecular and organic electronics. In this work, we report a facile method for forming robust and covalent bonding contacts between unprotected terminal acetylenes and metal (Ag) interfaces. Using this approach, we study the charge transport properties of conjugated oligophenylenes with covalent metal–carbon contacts to silver electrodes formed from unprotected terminal acetylene anchors. We performed single molecule charge transport experiments and molecular simulations on a series of arylacetylenes using gold and silver electrodes. Our results show that molecular junctions on silver electrodes spontaneously form silver–carbynyl carbon (Ag–C) contacts, resulting in a nearly 10-fold increase in conductance compared to the same molecules on gold electrodes. Overall, this work presents a simple, new electrode–anchor pair that reliably forms molecular junctions with stable and robust contacts for molecular electronics.

Three dimensional (3D) supramolecules with giant cavities are attractive due to their wide range of applications. Herein, we used pentatopic terpyridine ligands with three types of coordination moieties to assemble two giant supramolecular hexagonal prisms with a molecular weight up to 42 608 and 43 569 Da, respectively. Within the prisms, two double-rimmed Kandinsky Circles serve as the base surfaces as well as the templates for assisting the self-sorting during the self-assembly. Additionally, hierarchical self-assembly of these supramolecular prisms into tubular-like nanostructures was fully studied by scanning tunneling microscopy (STM) and small-angle X-ray scattering (SAXS). Finally, these supramolecular prisms show good antimicrobial activities against Gram-positive pathogen methicillin-resistant Staphylococcus aureus (MRSA) and Bacillus subtilis (B. subtilis).

We report the preparation and emission properties of tetraphenylethylene (TPE)-based metallacages with aggregation-induced emission (AIE) activities through coordination-driven self-assembly. Two supramolecular cages, [Zn 6 LA 3 ] and [Zn 6 LB 3 ], were assembled via TPE-decorated terpyridine (tpy) ligands, LA and LB, respectively, with Zn(II) ions. We performed a subtle change by introducing extra alkyne connectivity into LB to increase the degree of conjugation and geometric constraint, compared with LA. As a result, we obtained a highly emissive cage, [Zn 6 LB 3 ], even in a dilute solution. At a low temperature, the intramolecular rotation of TPE was further restricted, thus, resulting in a significant increase in fluorescence. Through mixing LA and LB, we obtained a series of hybrid cages, which also indicated that the emission was enhanced with highly abundant LB in the cages. Further, we studied the emission behaviors of the ligands and cages in solid state under external pressure. Upon gradual increase of the external pressure, the luminescence of [Zn 6 LB 3 ] increased initially, due to further rotation restriction, which was followed by quenching under 6.32 Gpa, owing to the tight packing of the supramolecules. The subsequent release of the pressure resulted in cage recovery of the emission.