"Pop goes the particle". Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery.

The morphology of the active layer in organic photovoltaics is critical in the optimization of device efficiencies. Most strategies aimed at improving morphology are focused mainly on annealing methods or the use of solvent additives. By using diketopyrrolopyrrole derivatives as donors and [6,6]-phenyl-C71-butyric acid methyl ester as electron acceptors, we report here on the effect of hydrogen bonding on active layer morphology and solar cell efficiency. We specifically compared two asymmetric derivatives, one containing an amide bond capable of forming hydrogen bonds with one containing an ester bond in the same position. Although both molecules have very similar optoelectronic properties, films of the ester revealed greater crystallinity and π−π stacking as characterized by grazing incidence X-ray diffraction. In great contrast, active layers formed with the amide derivative formed short fiber-like supramolecular aggregates with much smaller domain sizes and less order as characterized by atomic force microscopy and X-ray diffraction. Interestingly, devices fabricated with the amide−fullerene combination have a greater short circuit current (J SC ) leading to a 50% increase in power conversion efficiency compared to devices formed with the ester derivative. We conclude that the effective competition of hydrogen bonding over extensive π−π stacking results in morphologies that lead to higher photovoltaic efficiencies. ■ INTRODUCTIONOrganic photovoltaics (OPVs) have attracted great attention due to their low-cost processing, 1 ease of synthesis, and molecular design versatility. 2−5 Recently, single-cell device power conversion efficiencies (PCE) for bulk heterojunction polymer systems over 7% 6−10 and small molecule systems with PCE over 6−8% 11−13 have been reported. Systems with covalent polymers as electron donors remain the best performing materials, but their inherent polydispersity generates batch-to-batch variability, 14 and it has been found that PCE is dependent on molecular weight, which may not always be easy to reproduce. 15 On the other hand, small molecules offer the advantage of a precise molecular weight and high purity without batch-to-batch variation, and possibly enhanced local crystallinity, which translates into higher mobilities. 16 However, the high degree of crystallinity can limit the solubility necessary for solution processing and create nonuniform morphologies in the active layer. 17 High PCE small molecule designs currently focus on optimizing electronic properties, using the so-called push−pull principle, 18 but improving the morphology of the active layer is a much less explored topic, even though it is a crucial parameter to obtain high performing devices. 19,20 Supramolecular chemistry is emerging as a strategy to use noncovalent interactions between monomers to generate ordered structures 21 for a broad spectrum of applications that range from energy to medicine. 22 To date, there are only a few reports on how performance in OPVs is affected by noncovalent interactions, such as ...

Coming together: Oligothymine is used as a template to self‐assemble complementary nonchiral naphthalene guests. Depending on the protonated state of the guest, left‐ or right‐handed DNA‐templated self‐assemblies are formed (see picture). The templated assembly processes were studied in detail with temperature‐dependent circular dichroism and UV/Vis spectroscopy.

This feature article reports on the use of DNA as a template to assemble dyes and π-conjugated systems with the aim to construct functional multicomponent nanostructures that have a well-defined size, shape and sequence.