Through a combination of structural chemistry, vibrational spectroscopy, and theory, we have systematically examined the relative structure-directing importance of a series of ditopic halogen-bond (XB) donors. The molecular electrostatic potential surfaces of six XB donors were evaluated, which allowed for a charge-based ranking. Each molecule was then co-crystallized with 21 XB acceptors and the results have made it possible to map out the supramolecular landscape describing the competition between I/Br-ethynyl donors, perfluorinated I/Br donors, and I/Br-phenyl based donors. The results offer practical guidelines for synthetic crystal engineering driven by robust and directional halogen bonds.

3-Iodo-2-propynyl-N-butylcarbamate (IPBC) is an iodinated antimicrobial product used globally as a preservative, fungicide, and algaecide. IPBC is difficult to obtain in pure form as well as to handle in industrial products because it tends to be sticky and clumpy. Here, we describe the preparation of four pharmaceutical cocrystals involving IPBC. The obtained cocrystals have been characterized by X-ray diffraction, solution and solid-state NMR, IR, and DSC analyses. In all the described cases the halogen bond (XB) is the key interaction responsible for the self-assembly of the pharmaceutical cocrystals thanks to the involvement of the 1-iodoalkyne moiety of IPBC, which functions as a very reliable XB-donor, with both neutral and anionic XB-acceptors. Most of the obtained cocrystals have improved properties with respect to the source API, in terms, e.g., of thermal stability. The cocrystal involving the GRAS excipient CaCl2 has superior powder flow characteristics compared to the pure IPBC, representing a promising solution to the handling issues related to the manufacturing of products containing IPBC.

Carbon nano-onions (CNOs) are an exciting class of carbon nanomaterials, which have recently demonstrated a facile cell-penetration capability. In the present work, highly fluorescent boron dipyrromethene (BODIPY) dyes were covalently attached to the surface of CNOs. The introduction of this new carbon nanomaterial-based imaging platform, made of CNOs and BODIPY fluorophores, allows for the exploration of synergetic effects between the two building blocks and for the elucidation of its performance in biological applications. The high fluorescence intensity exhibited by the functionalized CNOs translates into an excellent in vitro probe for the high resolution imaging of MCF-7 human breast cancer cells. It was also found that the CNOs, internalized by the cells by endocytosis, localized in the lysosomes and did not show any cytotoxic effects. The presented results highlight CNOs as excellent platforms for biological and biomedical studies due to their low toxicity, efficient cellular uptake and low fluorescence quenching of attached probes.

Developing new tools that outperform current state of the art technologies for imaging, drug delivery or electrical sensing in neuronal tissues is one of the great challenges in neurosciences. Investigations into the potential use of carbon nanomaterials for such applications started about two decades ago. Since then, numerous in vitro studies have examined interactions between these nanomaterials and neurons, either by evaluating their compatibility, as vectors for drug delivery, or for their potential use in electric activity sensing and manipulation. The results obtained indicate that carbon nanomaterials may be suitable for medical therapies. However, a relatively small number of in vivo studies have been carried out to date. In order to facilitate the transformation of carbon nanomaterial into practical neurobiomedical applications, it is essential to identify and highlight in the existing literature the strengths and weakness that different carbon nanomaterials have displayed when probed in vivo. Unfortunately the current literature is sometimes sparse and confusing. To offer a clearer picture of the in vivo studies on carbon nanomaterials in the central nervous system, we provide a systematic and critical review. Hereby we identify properties and behavior of carbon nanomaterials in vivo inside the neural tissues, and we examine key achievements and potentially problematic toxicological issues.