Film thickness dependence of nanoscale arrangement of a chiral electron donor in its blends with an achiral electron acceptor.

The nanoscale chiral arrangement in a bicomponent organic material system comprising donor and acceptor small molecules is shown to depend on the thickness of a film that is responsive to chiral light in an optoelectronic device. In this bulk heterojunction, a previously unreported chiral bis(diketopyrrolopyrrole) derivative was combined with an achiral non-fullerene acceptor. The optical activity of the chiral compound is dramatically different in the pure material and the composite, showing how the electron acceptor influences the donor's arrangement compared with the pure molecule.

Wireless electrical-molecular quantum signalling for cancer cell apoptosis.

Quantum biological tunnelling for electron transfer is involved in controlling essential functions for life such as cellular respiration and homoeostasis. Understanding and controlling the quantum effects in biology has the potential to modulate biological functions. Here we merge wireless nano-electrochemical tools with cancer cells for control over electron transfer to trigger cancer cell death.

Molecular Surface Quantification of Multifunctionalized Gold Nanoparticles Using UV-Visible Absorption Spectroscopy Deconvolution.

Multifunctional gold nanoparticles (AuNPs) are of great interest, owing to their vast potential for use in many areas including sensing, imaging, delivery, and medicine. A key factor in determining the biological activity of multifunctional AuNPs is the quantification of surface conjugated molecules. There has been a lack of accurate methods to determine this for multifunctionalized AuNPs.

Self-assembly of chiral diketopyrrolopyrrole chromophores giving supramolecular chains in monolayers and twisted microtapes.

Chiral diketopyrrolopyrroles appended with enantiomeric ethyl lactate functions through an ether linkage to the aryl backbone of the chromophore were synthesized via the Mitsunobu reaction. The molecules have good solubility and excellent optical properties, high molar absorption coefficients, and fluorescence quantum yields. Helical aggregates with circular dichroism arising from the supramolecular arrangement are seen in both solution and thin films, and the aggregates also display circularly polarized luminescence (g  ≈ ±0.

Self-Assembled Surfactant-Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium-Ion Batteries.

The mixing of [V O ] decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self-assembly of surfactant-templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge-like V O (gem-V O ). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V O consisting of very small crystallites (TBA-V O ).

Highly electron deficient diketopyrrolopyrroles.

The synthesis, spectroelectrochemical and structural characteristics of highly electron-accepting diketopyrrrolopyrrole (DPP) molecules with adjoining pyridinium rings is reported, along with an assessment of their toxicity, which is apparently low. The compounds show reversible electrochemistry and in one subfamily a massive increase in molar extinction coefficient upon electrochemical reduction.

Submolecular Resolution Imaging of P3HT:PCBM Nanostructured Films by Atomic Force Microscopy: Implications for Organic Solar Cells.

The efficiency of organic bulk-heterojunction (BHJ) solar cells depends greatly on both the bulk and surface structure of the nanostructured bicontinuous interpenetrating network of materials, known as the active layer. The morphology of the top layer of a coated film is often resolved at the scale of a few nanometers, but fine details of the domains and the order within them are more difficult to identify. Here, we report a high-resolution atomic force microscopy (AFM) investigation of various stoichiometries of the well-studied poly(3-hexylthiophene):[6,6]-phenyl C butyric acid methyl ester (P3HT:PCBM) active layer mixture.

Low-Temperature Sintering of l-Alanine-Functionalized Metallic Copper Particles Affording Conductive Films with Excellent Oxidative Stability.

Here, the alpha amino acid l-alanine is employed as both a capping and stabilizing agent in the aqueous synthesis of submicron-sized metallic copper particles under ambient atmospheric conditions. The reduction of the copper(II) precursor is achieved using l-ascorbic acid (vitamin C) as the reducing agent. The nature of the complex formed between l-alanine and the copper(II) precursor, pH of the medium, temperature, and the relative proportion of capping agent are found to play a significant role in determining the size, shape, and oxidative stability of the resulting particles.

Imaging deposition-dependent supramolecular chiral organisation.

Thin films of a chiral diketopyrrolopyrrole derivative were imaged with spatially-defined Mueller Matrix Polarimetry, focussing on the Circular Dichroism signal, giving unique insight into the impact that deposition techniques and thermal annealing can have on chiral supramolecular structures in the solid state, where homogeneity was observed for spun-coated films while drop-coating afforded chiroptical diversity in the material, a feature invisible to absorption spectroscopy or optical microscopy.

Light-controlled micron-scale molecular motion.

The micron-scale movement of biomolecules along supramolecular pathways, mastered by nature, is a remarkable system requiring strong yet reversible interactions between components under the action of a suitable stimulus. Responsive microscopic systems using a variety of stimuli have demonstrated impressive relative molecular motion. However, locating the position of a movable object that travels along self-assembled fibres under an irresistible force has yet to be achieved.

Tuning Single-Molecule Conductance in Metalloporphyrin-Based Wires via Supramolecular Interactions.

Nature has developed supramolecular constructs to deliver outstanding charge-transport capabilities using metalloporphyrin-based supramolecular arrays. Herein we incorporate simple, naturally inspired supramolecular interactions via the axial complexation of metalloporphyrins into the formation of a single-molecule wire in a nanoscale gap. Small structural changes in the axial coordinating linkers result in dramatic changes in the transport properties of the metalloporphyrin-based wire.

Modulating the biological function of protein by tailoring the adsorption orientation on nanoparticles.

Protein orientation in nanoparticle-protein conjugates plays a crucial role in binding to cell receptors and ultimately, defines their targeting efficiency. Therefore, understanding fundamental aspects of the role of protein orientation upon adsorption on the surface of nanoparticles (NPs) is vital for the development of clinically important protein-based nanomedicines. In this work, new insights on the effect of the different orientation of cytochrome c (cyt c) bound to gold nanoparticles (GNPs) using various ligands on its apoptotic activity is reported.

Chirality from scratch: enantioselective adsorption in geometrically controlled lateral nanoconfinement.

Chiral symmetry breaking in molecular adsorption at the solid/liquid interface by lateral geometric nanoconfinement is demonstrated. The chiral nanoconfinement is created at the interface of achiral covalently modified highly-oriented pyrolytic graphite and a racemate by in situ scanning probe lithography. Enantioselective adsorption of chiral molecules is achieved by adjusting the relative orientation between the nanoconfining walls and substrate symmetry direction.

Natural optical activity as the origin of the large chiroptical properties in π-conjugated polymer thin films.

Polymer thin films that emit and absorb circularly polarised light have been demonstrated with the promise of achieving important technological advances; from efficient, high-performance displays, to 3D imaging and all-organic spintronic devices. However, the origin of the large chiroptical effects in such films has, until now, remained elusive. We investigate the emergence of such phenomena in achiral polymers blended with a chiral small-molecule additive (1-aza[6]helicene) and intrinsically chiral-sidechain polymers using a combination of spectroscopic methods and structural probes.

Sustainable sorbitol-derived compounds for gelation of the full range of ethanol-water mixtures.

During the development of soft material systems inspired by green chemistry, we show that naturally occurring starting materials can be used to prepare mono- and di-benzylidene sorbitol derivatives. These compounds gelate a range of organic, aqueous (including with mono and divalent metal salt solutions) and ethanolic (ethanol-water) solutions, with the equimolar mixture of two of the gelators gelling all compositions from 100% ethanol to 100% water (something neither of the individual components do). We explored the influence of modifications to the acetal substituents on the formation of the compounds as well as the impact of steric bulk on self-assembly properties of the gelators.

Quantification of energy of activation to supramolecular nanofibre formation reveals enthalpic and entropic effects and morphological consequence.

We show a self-assembly process leading to fibres from a system that starts far from equilibrium because of fast solvent - anti-solvent mixing and analyse the activation energies associated with the aggregation. It is in some ways reminiscent of diverse natural fibrous materials that have kinetic behaviour dominated by a rate limiting induction period followed by rapid growth. A full thermodynamic rationale for these systems and related synthetic ones is required for a full understanding of the driving force of their non-equilibrium self-assembly.

Ground and Excited States of Bis-4-Methoxybenzyl-Substituted Diketopyrrolopyrroles: Spectroscopic and Electrochemical Studies.

A series of symmetrically bis-4-methoxybenzyl (4MB) N-substituted 1,4-diketopyrrolo[3,4-c]pyrrole (DPP) derivatives have been synthesized. The 4MB unit makes the DPP core soluble, and shows subtle modification of up to 0.2 eV in ground and excited states of the core when compared with related alkyl derivatives.

Large Synthetic Molecule that either Folds or Aggregates through Weak Supramolecular Interactions Determined by Solvent.

Weak noncovalent interactions between large disclike molecules in poorly solvating media generally lead to the formation of fibers where the molecules stack atop one another. Here, we show that a particular chiral spacing group between large aromatic moieties, which usually lead to columnar stacks, in this case gives rise to an intramolecularly folded structure in relatively polar solvents, but in very apolar solvents forms finite aggregates. The molecule that displays this behavior has a symmetric benzene-1,3,5-tris(3,3'-diamido-2,2'-bipyridine) (BTAB) core with three metalloporphyrin units appended to it through short chiral spacers.

Preferred Formation of Minority Concomitant Polymorphs in 2D Self-Assembly under Lateral Nanoconfinement.

Control over polymorph formation in the crystallization of organic molecules remains a huge scientific challenge. Now, preferential formation is presented of one polymorph, formed by chiral molecules, in controlled two-dimensional (2D) nanoconfinement conditions at a liquid-solid interface. So-called nanocorrals to control concomitant polymorph formation were created in situ via a nanoshaving protocol at the interface between 1-phenyloctane and covalently modified highly-oriented pyrolytic graphite (HOPG).

Correction: Controlling the preferential motion of chiral molecular walkers on a surface.

[This corrects the article DOI: 10.1039/C9SC01135H.].

Controlling the preferential motion of chiral molecular walkers on a surface.

Molecular walkers standing on two or more "feet" on an anisotropic periodic potential of a crystal surface may perform a one-dimensional Brownian motion at the surface-vacuum interface along a particular direction in which their mobility is the largest. In thermal equilibrium the molecules move with equal probabilities both ways along this direction, as expected from the detailed balance principle, well-known in chemical reactivity and in the theory of molecular motors. For molecules that possess an asymmetric potential energy surface (PES), we propose a generic method based on the application of a time-periodic external stimulus that would enable the molecules to move preferentially in a single direction thereby acting as Brownian ratchets.

Ultra-high resolution imaging of thin films and single strands of polythiophene using atomic force microscopy.

Real-space images of polymers with sub-molecular resolution could provide valuable insights into the relationship between morphology and functionality of polymer optoelectronic devices, but their acquisition is problematic due to perceived limitations in atomic force microscopy (AFM). We show that individual thiophene units and the lattice of semicrystalline spin-coated films of polythiophenes (PTs) may be resolved using AFM under ambient conditions through the low-amplitude (≤ 1 nm) excitation of higher eigenmodes of a cantilever. PT strands are adsorbed on hexagonal boron nitride near-parallel to the surface in islands with lateral dimensions ~10 nm.

Self-Assembly of Chiral-at-End Diketopyrrolopyrroles: Symmetry Dependent Solution and Film Optical Activity and Photovoltaic Performance.

Chiral thiophene-diketopyrrolopyrrole derivatives have been synthesised to investigate the potential of stereochemistry and symmetry as a means of modulating properties by influencing self-assembly of these purely organic materials. In particular, derivatives of diketopyrrolopyrrole were employed because of their proven interest as dyes, especially for organic solar cells. The natural product myrtenal was used as the source of stereochemistry, introduced through a Kröhnke reaction of a thiophene-bearing pyridinium salt and diketopyrrolopyrroles were prepared through Suzuki coupling with this chiral moiety at one end only as well as at both ends.

Drug-Loaded Supramolecular Gels Prepared in a Microfluidic Platform: Distinctive Rheology and Delivery through Controlled Far-from-Equilibrium Mixing.

It is shown here that controlled mixing of a gelator, drug, solvent, and antisolvent in a microfluidic channel leads to faster setting gels and more robust materials with longer release profiles than the physical gels of the same composition obtained using random mixing in solution. The system is similar to a related gelator system we had studied previously, but we were unable to apply the same gelling procedure because of the instability of the colloid caused by the small structural modification (length of the alkyl chain in the bis-imidazolium head group). This situation holds true for the gels formed with varying compositions and under different conditions (gelator/drug ratio, solvent proportion, and flow rates), with the most significant differences being the improved gel rheology and slower drug release rates.