Crystalline Naphthylene Macrocycles Capturing Gaseous Small Molecules in Chiral Nanopores.

A series of chiral naphthylene macrocycles, [n]cyclo-epi-naphthylenes ([n]CeNAPs), possessing epi-linkages were synthesized by one-pot macrocyclization. With chiral (R)- or (S)-1,1'-linkages embedded in binaphthyl precursors, the macrocycles were assembled in polygonal structures possessing chiral hinges as corners. Among four chiral [n]CeNAP variants, [8]CeNAP with eight naphthylene panels formed robust columnar assemblies in crystals. The nanoporous crystals maintained a columnar assembly structure even after the removal of encapsulated solvent molecules, and their gas adsorption behavior was thoroughly investigated. Gas adsorption, including state-of-the-art in situ crystallographic analyses, revealed accurate atomic-level structures of the nanopores trapping gaseous N2 molecules in chiral C2 arrangements. With macrocycles as basic frameworks, functional nanopores may be exploited for chiral small-molecule alignments.

Author Correction: Concyclic CH-π arrays for single-axis rotations of a bowl in a tube.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Retarded Solid-State Rotations of an Oval-Shaped Guest in a Deformed Cylinder with CH-π Arrays.

Upon encapsulating an oval-shaped hydrocarbon guest, a cylindrical host deforms its shape to maximize intermolecular contacts. Structure-assembly relationship studies with a series of hydrocarbon guests disclosed the importance of molecular shapes and CH-π contacts. Multiple contacts and weak CH-π hydrogen bonds resulted in an optimal assembly; however, the shape deformation resulted in severe retardation of rotational motions in the crystal. Thus, unlike a circular guest, the oval-shaped guest did not change its orientation in the host. Unexpectedly, the planar guest did not affect the packing structure to form a double helix in intertwined host arrays.

In-stent restenosis assessed with frequency domain optical coherence tomography shows smooth coronary arterial healing process in second-generation drug-eluting stents.

INTRODUCTION: The pathophysiology and mechanism of in-stent restenosis (ISR) after implantation of second-generation drug-eluting stents (DESs) are not fully clear. We compared the morphological characteristics of ISR between first- and second-generation DESs using frequency domain optical coherence tomography (OCT). METHODS: Patients who underwent follow-up coronary angiography (CAG) after first-generation (CYPHER™ and TAXUS™) and second-generation (Nobori®, PROMUS Element™, Resolute Integrity and XIENCE) DES implantations were examined. ISR was defined as lesions of over 50% diameter stenosis at follow-up CAG. Frequency domain OCT was performed at the time of revascularisation of ISR. Tissue morphology was assessed at minimum lumen area. OCT images of DESs at both early (≤ 1 year) and late (> 1 year) phase follow-up were compared. RESULTS: On qualitative OCT assessment, the ratios of homogeneous, layered, heterogeneous without-attenuation and heterogeneous with-attenuation morphologies were 57.1%, 17.1%, 20.0% and 5.7%, respectively, for second-generation DES ISR (n = 35), and 16.7%, 25.0%, 25.0% and 33.3%, respectively, for first-generation DES ISR (n = 36). At late phase follow-up, homogeneous morphology was significantly more common for second-generation DES ISR compared to first-generation DES ISR (first-generation: 8.0% vs. second-generation: 50.0%; p < 0.01) while heterogeneous with-attenuation morphology was significantly more common for first-generation DES ISR (first-generation: 44.0% vs. second-generation: 5.6%; p < 0.01). CONCLUSION: Homogeneous tissue morphology was more frequently found for second-generation than first-generation DES ISR, especially in the late phase. This suggested that neointimal hyperplasia was the main mechanism in second-generation DES ISR, and that the neointima was stabilised, much like in bare metal stent implantation.

Concyclic CH-π arrays for single-axis rotations of a bowl in a tube.

The hydrogen bond is undoubtedly one of the most important non-covalent interactions. Among the several types of the hydrogen bonds, the CH-π interaction is a relatively new notion that is being recognised in chemistry and biology. Although the CH-π hydrogen bond and conventional hydrogen bonds share common features such as directionality, this weak interaction has played a secondary role in molecular recognition. In this study, we have devised a host-guest complex that is assembled solely by the CH-π hydrogen bonds. Multivalent interactions of a bowl-shaped hydrocarbon with its peripheral hydrogen atoms are made possible via CH-π hydrogen bonds by adopting a tubular hydrocarbon as a host for their enthalpy-driven complexation. Concyclic arrays of weak hydrogen bonds further allow dynamic rotational motions of the guest in the host. Solid-state analysis with crystallographic and spectroscopic methods reveal a single-axis rotation of the bowl in the tube.