Designed 3D heterostructure by 0D/1D/2D hierarchy for low-frequency microwave absorption in the S-band

Developing a low-frequency tunable microwave absorber for the normal use of sophisticated electric devices is an urgent need for electromagnetic pollution. Herein, we report the designed synthesis of a three-dimensional...

On Borromean links and related structures

The creation of knotted, woven and linked molecular structures is an exciting and growing field in synthetic chemistry. Presented here is a description of an extended family of structures related to the classical `Borromean rings', in which no two rings are directly linked. These structures may serve as templates for the designed synthesis of Borromean polycatenanes. Links of n components in which no two are directly linked are termed `n-Borromean' [Liang & Mislow (1994). J. Math. Chem. 16, 27–35]. In the classic Borromean rings the components are three rings (closed loops). More generally, they may be a finite number of periodic objects such as graphs (nets), or sets of strings related by translations as in periodic chain mail. It has been shown [Chamberland & Herman (2015). Math. Intelligencer, 37, 20–25] that the linking patterns can be described by complete directed graphs (known as tournaments) and those up to 13 vertices that are vertex-transitive are enumerated. In turn, these lead to ring-transitive (isonemal) n-Borromean rings. Optimal piecewise-linear embeddings of such structures are given in their highest-symmetry point groups. In particular, isonemal embeddings with rotoinversion symmetry are described for three, five, six, seven, nine, ten, 11, 13 and 14 rings. Piecewise-linear embeddings are also given of isonemal 1- and 2-periodic polycatenanes (chains and chain mail) in their highest-symmetry setting. Also the linking of n-Borromean sets of interleaved honeycomb nets is described.

Designed Synthesis of Diversely Substituted Hydantoins and Hydantoin-Based Hybrid Molecules: A Personal Account

Hydantoin and its analogs such as thiohydantoin and iminohydantoin have received substantial attention both from a chemical and biological point of view. Several compounds of this class have shown useful pharmacological activities such as anticonvulsant, antitumor, antiarrhythmic, herbicidal, and others that lead in some cases to clinical applications. Because of broad-spectrum activities, intensive research efforts have been dedicated in industry and academia to the synthesis and structural modifications of hydantoin and its derivatives. Realizing the importance of hydantoin in organic and medicinal chemistry, we also initiated a research program to successfully design and develop the new routes/methods resulting in the formation of hydantoin, thiohydantoin, and iminohydantoin substituted at different positions particularly at the N-1 position without following protection-deprotection strategy. Given the fact that the combination of two or more pharmacophoric groups may lead to hybrid molecules which result in a mixed mechanism of action on the biological target. We, therefore, further extended the developed strategy for the synthesis of new types of hydantoin-based hybrid molecules by combining hydantoin with a triazole, isoxazoline, and phosphate scaffolds as another pharmacophoric group to exploit diverse biological functions.