Single-atom-catalysts (SACs) afford a fascinating activity with respect to other nanomaterials for hydrogen evolution reaction (HER), yet the simplicity of single-atom center limits its further modification and utilization. Obtaining bimetallic single-atom-dimer (SAD) structures can reform the electronic structure of SACs with added atomic-level synergistic effect, further improving HER kinetics beyond SACs. However, the synthesis and identification of such SAD structure remains conceptually challenging. Herein, systematic first-principle screening reveals that the synergistic interaction at the NiCo-SAD atomic interface can upshift the d-band center, thereby, facilitate rapid water-dissociation and optimal proton adsorption, accelerating alkaline/acidic HER kinetics. Inspired by theoretical predictions, we develop a facile strategy to obtain NiCo-SAD on N-doped carbon (NiCo-SAD-NC) via in-situ trapping of metal ions followed by pyrolysis with precisely controlled N-moieties. X-ray absorption spectroscopy indicates the emergence of Ni-Co coordination at the atomic-level. The obtained NiCo-SAD-NC exhibits exceptional pH-universal HER-activity, demanding only 54.7 and 61 mV overpotentials at −10 mA cm−2 in acidic and alkaline media, respectively. This work provides a facile synthetic strategy for SAD catalysts and sheds light on the fundamentals of structure-activity relationships for future applications.

Reports of a high-affinity ligand for E-selectin, sialyl di-Lewis(x) (sLe(x)Le(x), 1), motivated us to incorporate modifications to previously reported biphenyl-based inhibitors that would provide additional interactions with the protein. These compounds were assayed for the ability to inhibit the binding of sialyl Lewis(x) (sLe(x), 2) bearing HL-60 cells to E-, P-, and L-selectin fusion proteins. We report that dimeric or trimeric compounds containing multiple components of simple nonoligosaccharide selectin antagonists inhibit sLe(x)-dependent binding with significantly enhanced potency over the monomeric compound. The enhanced potency is consistent with additional binding interactions within a single selectin lectin domain; however, multivalent interaction with multiple lectin domains as a possible alternative cannot be ruled out. Compound 15e (TBC1269) showed optimal in vitro activity from this class of antagonists and is currently under development for use in the treatment of asthma.

Sitaxsentan (1) (Wu et al. J. Med. Chem. 1997, 40, 1690) is our first endothelin antagonist being evaluated in clinical trials. It has demonstrated biological effects in an acute hemodynamic study in CHF (Givertz et al. Circulation 2000, 101, 2922), an open-label 20-patient pulmonary hypertension trial (Barst et al. Chest 2002, 121, 1860-1868), and a 31-patient trial in essential hypertension (Calhoun et al. AHA Scientific Sessions 2000). In a phase 2b/3 pulmonary arterial hypertension trial, once a day treatment of 100 mg of sitaxsentan statistically significantly improved 6-min walk distance and NYHA class at 12 weeks (Barst et al. Am. J. Respir. Crit. Care Med. 2004, 169, 441). We have since reported on our efforts in generating follow-up compounds (Wu et al. J. Med. Chem. 1999, 42, 4485) and recently communicated that an ortho acyl group on the anilino ring enhanced oral absorption in this category of compounds (Wu et al. J. Med. Chem. 2001, 44, 1211). Here we report an expansion of this work by substituting a variety of electron-withdrawing groups at the ortho position and evaluating their effects on oral bioavailability as well as structure-activity relationships. As a result, TBC3711 (7z) was identified as our second endothelin antagonist to enter the clinic due to its good oral bioavailability (approximately 100%) in rats, high potency (ET(A) IC(50) = 0.08 nM), and optimal ET(A)/ET(B) selectivity (441 000-fold). Compound 7z has completed phase-I clinical development and was well tolerated with desirable pharmacokinetics in humans (t(1/2) = 6-7 h, oral availability > 80%).

Amorphization of the support in single‐atom catalysts is a less researched concept for promoting catalytic kinetics through modulating the metal–support interaction (MSI). We modeled single‐atom ruthenium (RuSAs) supported on amorphous cobalt/nickel (oxy)hydroxide (Ru‐a‐CoNi) to explore the favorable MSI between RuSAs and the amorphous skeleton for the alkaline hydrogen evolution reaction (HER). Differing from the usual crystal counterpart (Ru‐c‐CoNi), the electrons on RuSAs are facilitated to exchange among local configurations (Ru‐O‐Co/Ni) of Ru‐a‐CoNi since the flexibly amorphous configuration induces the possible d–d electron transfer and medium‐to‐long range p–π orbital coupling, further intensifying the MSI. This embodies Ru‐a‐CoNi with enhanced water dissociation, alleviated oxophilicity, and rapid hydrogen migration, which results in superior durability and HER activity of Ru‐a‐CoNi, wherein only 15 mV can deliver 10 mA cm−2, significantly lower than the 58 mV required by Ru‐c‐CoNi.

The exact understanding for each promotional role of cation and anion vacancies in bifunctional water splitting activity will assist in the development of an efficient activation strategy of inert catalysts. Herein, systematic first-principles computations demonstrate that the synergy of anion-oxygen and cation-manganese vacancies (V O and V Mn ) in manganese dioxide (MnO 2 ) nanosheets results in abnormal local lattice distortion and electronic modulation. Such alterations enrich the accessible active centers, increase conductivity, enhance the water dissociation step, and favor intermediate adsorption-desorption, consequently promoting HER and OER kinetics. As proof of concept, robust electrocatalysts, MnO 2 ultrathin nanosheets doped with dual vacancies (DV-MnO 2 ) are obtained via a maturely chemical strategy. Detailed characterizations confirm the cation vacancies-V Mn contribute to enhanced conductivity and anion vacancies-V O enrich the active centers with optimized local electronic configurations, consistent with the simulative predictions. As expected, DV-MnO 2 exhibits exceptional bifunctionality with the strong assistance of synergetic dual vacancies which act as abundant "hot spots" for active multiple intermediates. Leading to a lower cell voltage (1.55 V) in alkali electrolyte is required to reach 10 mA cm −2 for the overall water splitting system. These atomic-level insights on synergetic DV can favor the development of activating strategy from inert electrocatalysts.

The calcium dependent E-selectin/sialyl Lewisx (sLex) interaction plays a key role in inflammation where it mediates the rolling of leukocytes prior to firm adhesion and extravasation from the vasculature. A model of E-selectin/sLex binding, along with previously reported structure-activity relationships of sLex-related oligosaccharide, was used in the rational design of non-oligosaccharide inhibitors of this pivotal interaction. A palladium-mediated biaryl-coupling (Suzuki) reaction was used as the key step to prepare a number of substituted biphenyls which were assayed for their ability to inhibit the binding of E-, P-, and L-selectin-IgG fusion proteins to sLex expressed on the surface of HL60 cells. Some of the compounds developed had greater in vitro potency than the parent sLex tetrasaccharide and are currently being evaluated in in vivo models of inflammation to select a candidate for clinical development.

A possible role of a model biomembrane, liposome, in gene expression was investigated by using the cell-free translation system. A reporter protein, green fluorescence protein (GFP), was expressed in vitro with and without liposome prepared with 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphatidyl chorine (POPC) and cholesterol (Ch) (5.7 mM lipid concentration). In the presence of POPC/Ch liposome, the fluorescence intensity of produced GFP was found to be 1.67 times higher than that in the control after 18 h of expression. The results of the SDS-PAGE analysis also show the above promotion effect of the liposome on the net expression of the GFP gene (1.58 times more). The amounts of mRNA were found to be promoted to 1.29 times higher than those in the control. The differences among mRNA, net expression of the GFP gene, and GFP fluorescence indicate that the enhanced GFP expression in the presence of POPC/Ch liposome could primarily affect the transcription and translation of the GFP gene among the possible steps of gene expression. The variation of in vitro gene expression with various liposomes also shows that the biomembrane could act as a modulator to split the genotype and phenotype in a biological cell.

No abstract