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Structurally modified nucleosides are central players in the field of nucleic acid chemistry. Adenine-thymine (AT) pyrimido[4,5-d]pyrimidine furanosyl and pyranosyl arabinonucleosides have been synthesized for the first time. Single-crystal X-ray diffraction analysis reveals novel base pairs that, in synergy with the sugar residues, direct the emergence of distinct networks containing channels and cavities. The microscopic noncovalent connections can be translated into macroscopic levels in which robust organogels are formed by the furanoside but not the pyranoside. The influences of the sugars are also displayed by the different shaped superstructures of the free nucleosides in solution. The readout of the information in the base moiety is therefore tailored by the sugar configuration, and the interplays exert subtle effects on the structures, from solid to gel and to the solution state. The potential for forming these appealing base pairs and higher structures enables these intriguing nucleosides to serve as unique building blocks in various areas or to construct innovative nucleic acid structures. [ABSTRACT FROM AUTHOR]

Supramolecular assembly: Spherical and stable hybrid assemblies based on a cationic polymer with spermine side chains and an anionic Gd3+‐containing polyoxometalate cluster (GdW) are prepared by electrostatic interaction (see figure). The T1‐weighted MRI performance of GdW is enhanced about three times in the assemblies; meanwhile, the assemblies show good biocompatibility, which enables them to be promising candidates for MRI contrast agents. [ABSTRACT FROM AUTHOR]