A modular approach towards functionalized highly stable self-complementary quadruple hydrogen bonded systems

2-Amino-5-methylene-pyrimidine-4,6-dione-based Janus G-C nucleobase as a versatile building block for self-assembly

This communication reports a nature-inspired Janus G-C nucleobase featuring two recognition sites: DDA (G mimic) and DAA (C mimic), which is capable of forming a linear tape-like supramolecular polymer structure. As demonstrated herein, the amino group of this self-assembling system can be further modified to yield a highly stable quadruple H-bonding system as well as a masked self-assembling system cleavable upon exposure to light.

Towards photoswitchable quadruple hydrogen bonds via a reversible "photolocking" strategy for photocontrolled self-assembly

Developing new photoswitchable noncovalent interaction motifs with controllable bonding affinity is crucial for the construction of photoresponsive supramolecular systems and materials. Here we describe a unique "photolocking" strategy for realizing photoswitchable control of quadruple hydrogen-bonding interactions on the basis of modifying the ureidopyrimidinone (UPy) module with an ortho-ester substituted azobenzene unit as the "photo-lock". Upon light irradiation, the obtained Azo-UPy motif is capable of unlocking/locking the partial H-bonding sites of the UPy unit, leading to photoswitching between homo- and heteroquadruple hydrogen-bonded dimers, which has been further applied for the fabrication of novel tunable hydrogen bonded supramolecular systems. This "photolocking" strategy appears to be broadly applicable in the rational design and construction of other H-bonding motifs with sufficiently photoswitchable noncovalent interactions.

Assembly of miscible supramolecular network blends using DDA·AAD hydrogen-bonding interactions of pendent side-chains

Miscible blends of poly(methyl methacrylate) and polystyrene polymers are assembled through triple hydrogen bonding between complementary ureidoimidazole and amidoisocytosine heterodimers.

Supramolecular Self-Sorting Networks using Hydrogen-Bonding Motifs

A current objective in supramolecular chemistry is to mimic the transitions between complex self-sorted systems that represent a hallmark of regulatory function in nature. In this work, a self-sorting network, comprising linear hydrogen motifs, was created. Selecting six hydrogen-bonding motifs capable of both high-fidelity and promiscuous molecular recognition gave rise to a complex self-sorting system, which included motifs capable of both narcissistic and social self-sorting. Examination of the interactions between individual components, experimentally and computationally, provided a rationale for the product distribution during each phase of a cascade. This reasoning holds through up to five sequential additions of six building blocks, resulting in the construction of a biomimetic network in which the presence or absence of different components provides multiple unique pathways to distinct self-sorted configurations.