Halogen bonding (XB) is a highly directional, noncovalent intermolecular interaction between a molecule (XB donor) presenting a halogen with an electron-deficient region or sigma hole (σhole) and an electron-rich or Lewis-base molecule (XB acceptor). A systematic, experimental, and theoretical study of solution-phase XB strength as a function of the molecular structure for both XB donor and acceptor molecules is presented. The impact of specific structural features is assessed using 19 F and 1 H nuclear magnetic resonance (NMR) titrations to determine association constants, density functional theory calculations for interaction energies and bond lengths, as well as 19 F− 1 H HOESY NMR measurements of intermolecular cross-relaxation between the interacting XB donor−acceptor adducts. For XB donor molecules (perfluoro-halogenated benzenes), results indicate the critical importance of iodine coupled with electron-withdrawing entities. Prominent structural components of XB acceptor molecules include a central atom working in conjunction with a Lewisbase atom to present high electron density directed at the σ-hole (e.g., tributylphosphine oxide). Additionally, larger surrounding aliphatic R groups (e.g., butyl and octyl) were found to significantly stabilize strong XB, particularly in solvents that promote the interaction. With a more thorough understanding of structure-optimized XB, one can envision harnessing XB interactions more strategically for specific design of optimal materials and chemical applications.

The use of functionalized nanoparticles (NPs) and their aggregation in the presence of a targeted analyte is a wellestablished molecular detection strategy predicated on harnessing specific molecular interactions to the NP periphery. Molecules able to specifically interact with the functionalized NPs alter the unique optical and electrochemical properties of the NPs as a function of interparticle spacing. While many intermolecular interactions have been successfully exploited in this manner in conjunction with aqueous NP systems, the use of non-aqueous NPs in the same capacity is significantly less explored. A fundamental interaction that has not been previously investigated in NP schemes is halogen bonding (XB). XB is an orthogonal, electrostatic interaction between a region of positive electrostatic potential (δ+) on a halogen atom (i.e., XB donor) and a negative (δ−) Lewis base (XB acceptor) molecule. To couple XB with NP systems, ligands featuring a molecular structure that promotes XB interactions need to be identified, optimized, and synthesized for subsequent attachment to NPs. Herein, density functional theory (DFT) and NMR techniques are used to identify a strong XB-donor moiety (−C 6 F 4 I) and a synthetic scheme for a thiolate ligand featuring that functionality is devised and executed with high purity/yield (78%). Ligand-exchange reactions allow functionalization of non-aqueous alkanethiolate-protected gold NPs or monolayer-protected clusters (MPCs) with the XB-donor ligands. Functionalized MPCs (f-MPCs), within both assembled films and in solution, are shown to engage in XB interactions with target XB-acceptor molecules. Molecular recognition events, including induced aggregation of the f-MPCs, are characterized with UV−vis spectroscopy, cyclic voltammetry, TEM imaging, and diffusion-ordered spectroscopy NMR with limits of detection of 50−100 nM for strong XB acceptors. While fundamental exploration of XB interactions is ongoing, this study represents a step toward utilizing XB within molecular detection schemes, an application with implications for supramolecular chemistry, forensic, and environmental chemical sensing.

Neonicotinoid (NN) pesticides have emerged globally as one of the most widely used agricultural tools for protecting crops from pest damage and boosting food production. Unfortunately, some NN compounds, such as extensively employed imidacloprid-based pesticides, have also been identified as likely endangering critical pollinating insects like honey bees. To this end, NN pesticides pose a potential threat to world food supplies. As more countries restrict or prohibit the use of NN pesticides, tools are needed to effectively and quickly identify the presence of NN compounds like imidacloprid on site (e.g., in storage areas on farms or pesticide distribution warehouses). This study represents a proof-of-concept where the colloidal properties of specifically modified gold nanoparticles (Au-NPs) able to engage in the rare intermolecular interaction of halogen bonding (XB) can result in the detection of certain NN compounds. Density functional theory and diffusion-ordered NMR spectroscopy (DOSY NMR) are used to explore the fundamental XB interactions between strong XBdonor structures and NN compounds, with the latter found to possess multiple XB-acceptor binding sites. A fundamental understanding of these XB interactions allows for the functionalization of alkanethiolate-stabilized Au-NPs, known as monolayerprotected gold clusters (MPCs), with XB-donor capability (f-MPCs). In the presence of certain NN compounds such as imidacloprid, the f-MPCs subsequently exhibit visual XB-induced aggregation that is also measured with absorption (UV−vis) spectroscopy and verified with transmission electron microscopy (TEM) imaging. The demonstrated f-MPC-aggregation detection scheme has a number of favorable attributes, including quickly reporting the presence of the NN target, requiring only micrograms of suspect material, and being highly selective for imidacloprid, the most prevalent and most important NN insecticide compound. Requiring no instrumentation, the presented methodology can be envisioned as a simple screening test in which dipping a cotton swab of an unknown powder from a surface in a f-MPC solution causes f-MPCs to aggregate and yield a preliminary indication of imidacloprid presence.

With the aging of the population, malignancies are becoming common complications in patients with rheumatoid arthritis (RA), particularly in elderly patients. Such malignancies often interfere with RA treatment. Among several therapeutic agents, immune checkpoint inhibitors (ICIs) which antagonize immunological brakes on T lymphocytes have emerged as a promising treatment option for a variety of malignancies. In parallel, evidence has accumulated that ICIs are associated with numerous immune-related adverse events (irAEs), such as hypophysitis, myocarditis, pneumonitis, and colitis. Moreover, ICIs not only exacerbate pre-existing autoimmune diseases, but also cause de novo rheumatic disease–like symptoms, such as arthritis, myositis, and vasculitis, which are currently termed rheumatic irAEs. Rheumatic irAEs differ from classical rheumatic diseases in multiple aspects, and treatment should be individualized based on the severity. Close collaboration with oncologists is critical for preventing irreversible organ damage. This review summarizes the current evidence regarding the mechanisms and management of rheumatic irAEs with focus on arthritis, myositis, and vasculitis. Based on these findings, potential therapeutic strategies against rheumatic irAEs are discussed.

Total humeral replacement is a complex surgery that requires many challenges to overcome such as the weight of the implant material and the shoulder function due to extensive resection of the rotator cuff. Improvements in implants material that is lighter than usual can lead to higher surgery success rates. We present a patient who was diagnosed with osteosarcoma of the right humerus. The patient received 2 cycles of MAP chemotherapy (included: doxorubicin, cisplatin, and methotrexate) before surgery. He underwent radical resection of osteosarcoma and total humerus replacement with a modified total humeral material. The purpose of this improvement was to reduce the implant’s weight and to improve postoperative recovery. Six months after the surgery, the weight-bearing ability of the patient’s shoulder within a wide range of movement has restored; the shoulder, elbow, and hand can move in a controlled way. Despite the short postoperative follow-up time, the improvement in the modified technique has brought many positive results. Total humerus replacement, which combines the reverse shoulder prosthesis, elbow prosthesis, and polyetheretherketone, is an appropriate solution for patients with osteosarcoma of the humerus instead of custom-made humerus megaprosthesis.