The direct functionalization of C-H bonds has drawn the attention of chemists for almost a century. C-H activation has mainly been achieved through four metal-mediated pathways: oxidative addition, electrophilic substitution, σ-bond metathesis and metal-associated carbene/nitrene/oxo insertion. However, the identification of methods that do not require transition-metal catalysts is important because methods involving such catalysts are often expensive. Another advantage would be that the requirement to remove metallic impurities from products could be avoided, an important issue in the synthesis of pharmaceutical compounds. Here, we describe the identification of a cross-coupling between aryl iodides/bromides and the C-H bonds of arenes that is mediated solely by the presence of 1,10-phenanthroline as catalyst in the presence of KOt-Bu as a base. This apparently transition-metal-free process provides a new strategy with which to achieve direct C-H functionalization.

Intramolecular transport of vibrational energy in two series of oligomers featuring alkane chains of various length was studied by relaxation-assisted two-dimensional infrared spectroscopy. The transport was initiated by exciting various end-group modes (tags) such as different modes of the azido (ν(N≡N) and ν(N═N)), carboxylic acid (ν(C═O)), and succinimide ester (νas(C═O)) with short mid-IR laser pulses. It is shown that the transport via alkane chains is ballistic and the transport speed is dependent on the type of the tag mode that initiates the transport. The transport speed of 8.0 Å/ps was observed when initiated by either ν(C═O) or νas(C═O). When initiated by ν(N≡N) and ν(N═N), the transport speed of 14.4 ± 2 and 11 ± 4 Å/ps was observed. Analysis of the vibrational relaxation channels of different tags, combined with the results for the group velocity evaluation, permits identification of the chain bands predominantly contributing to the transport for different cases of the transport initiation. For the transport initiated by ν(N≡N) the CH2 twisting and wagging chain bands were identified as the major energy transport channels. For the transport initiated by ν(C═O), the C-C stretching and CH2 rocking chain bands served as major energy transporters. The transport initiated by ν(N═N) results in direct formation of the wave packet within the CH2 twisting and wagging chain bands. These developments can aid in designing molecular systems featuring faster and more controllable energy transport in molecules.

In materials, energy can propagate by means of two limiting regimes: diffusive and ballistic. Ballistic energy transport can be fast and efficient and often occurs with a constant speed. Using two-dimensional infrared spectroscopy methods, we discovered ballistic energy transport via individual polyethylene chains with a remarkably high speed of 1440 m/s and the mean free path length of 14.6 Å in solution at room temperature. Whereas the transport via the chains occurs ballistically, the mechanism switches to diffusive with the effective transport speed of 130 m/s at the end-groups attached to the chains. A unifying model of the transport in molecules is presented with clear time separation and additivity among the transport along oligomeric fragments, which occurs ballistically, and the transport within the disordered fragments, occurring diffusively. The results open new avenues for making novel elements for molecular electronics, including ultrafast energy transporters, controlled chemical reactors, and sub-wavelength quantum nanoseparators.

Host-guest complexes are emerging as powerful components in functional systems with applications ranging from materials to biomedicine. In particular, CB7 based host-guest complexes have received much attention for the controlled release of drugs due to the remarkable ability of CB7 toward binding input molecules in water with high affinity leading to displacement of CB7 from included pharmacophores (or from drug loaded porous particles). However, the release of bound guests from CB7 in response to endogenous biological molecules remains limited since the input biomolecule needs to have the appropriate chemical structure to bind tightly into the CB7 cavity. Herein we describe a synthetic transducer based on self-assembling DNA-small molecule chimeras (DCs) that is capable of converting a chosen biological input, adenosine triphosphate (ATP; that does not directly bind to the CB7 host) into functional displacement of a protein inhibitor that is bound within the CB7 host. Our system—which features the first example of a covalent CB-DNA conjugate—is highly modular and can be adapted to enable responsiveness to other biologically/clinically relevant stimuli via its split DNA aptamer architecture.