A new binding motif in molecular clips: 1-D polymeric self-inclusion in a phenol complex of a bis(methoxyphenyl)glycoluril

Chemoresponsive polymer systems for selective molecular recognition of organic molecules in biological systems

Smart polymer materials that respond to a chemical stimulus are applied for the construction of biomedical devices and purification/separation systems. Small organic molecules are a particular type of stimulus. Their abnormal concentration indisputably indicates certain diseases. They are also hazardous environment contaminants. Polymer materials, which structure is selectively changed in the presence of a defined organic compound are promising in view of regulation of certain biomedical functions, as well as in view of chemical detectors construction. This review summarizes the state of the art in the self-assemblies of amphiphilic copolymers and polymer networks sensitive toward organic species, with an emphasis on the reports from the last decade. We focus on the relationship between the selectivity of introduced receptor moieties responsible for the change of material structure, the overall structure of material and its functionality.

Synthesis of a monofunctional glycoluril molecular clip via cyclic imide formation on the convex site

We present a simple synthesis of a monohydroxylated glycoluril clip derivative prone to homodimerization from diester or diethanolamide clip derivatives.

Synthesis of glycolurils and their analogues

Glycolurils — tetrahydroimidazo[4,5-d]imidazole-2,5(1H,3H)-diones — have found widespread applications in various fields of science and technology. Among them, there are pharmacologically active compounds (antibacterial, nootropic, neurotropic agents, etc.), explosives, gelators, etc. They are used as building blocks in supramolecular chemistry. Therefore, the development of new methods for the synthesis of glycolurils and their analogues has constantly attracted the attention of researchers. In this review, we analyze various approaches to the synthesis of glycolurils and their analogues. The review covers both classical reactions of ureas and related compounds with α-dicarbonyl compounds or with 4,5-dihydroxyimida-zolidin-2-ones (-thiones) and their imino analogues and new original reactions of 4,5-dihydroxyimidazolidin-2-ones (-thiones), imidazolinones and their bicyclic analogues with ureas and KNCS in the presence of acids, condensations of 1,4-disubstituted 1,4-diaza-1,3-dienes with isocyanic and/or isothiocyanic acids or isocyanates, triazine ring contraction in imidazotriazines to give the imidazolidine ring, and transformations of urazoles.

The bibliography includes 129 references.

Glycoluril-tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

Glycoluril-based molecular clips incorporating tetrathiafulvalene (TTF) sidewalls have been synthesized through different strategies with the aim of investigating the effect of electrochemical and spatial properties for binding neutral accepting guests. We have in particular focused our study on the spacer extension in order to tune the intramolecular TTF···TTF distance within the clip and, consequently, the redox behavior of the receptor. Carried out at different concentrations in solution, electrochemical and spectroelectrochemical experiments provide evidence of mixed-valence and/or π-dimer intermolecular interactions between TTF units from two closed clips. The stepwise oxidation of each molecular clip involves an electrochemical mechanism with three one-electron processes and two charge-coupled chemical reactions, a scheme which is supported by electrochemical simulations. The fine-tunable π-donating ability of the TTF units and the cavity size allow to control binding interaction towards a strong electron acceptor such as tetrafluorotetracyanoquinodimethane (F4-TCNQ) or a weaker electron acceptor such as 1,3-dinitrobenzene (m-DNB).

Fused glycoluril-tetrathiafulvalene molecular clips as receptors for neutral electron acceptor guests

Glycoluril-based molecular clips incorporating tetrathiafulvalene (TTF) sidewalls have been synthesized, and the efficient binding ability in solution of this host architecture toward m-dinitrobenzene through donor-acceptor interaction has been demonstrated.

Glycoluril-derived crown clips as new ditopic receptors

Several new ditopic receptors have been synthesized from 4,4′-bis(methoxyphenyl)glycoluril (1). The first receptor site is a cleft composed of two fused 2-imidazolone rings, which are flanked by two aromatic side walls, and the second site is a crown ether moiety.Key words: receptors, crown compounds, glycoluril, molecular clips.

The First Immobilisation of Glycoluril-Based Molecular Clips on Silica Gel and Alumina

The first example of immobilisation of some glycoluril-based molecular clips, which are good receptors for dihydroxybenzenes, on silica gel and alumina is described. 4,4′-Bis(methoxyphenyl)glycoluril was used as the base scaffold for the synthesis of molecular clips. After demethylation of the methoxy groups, the clip compounds were attached to silica gel and alumina using the linker (3-chloropropyl)trimethoxysilane. The resulting clip-functionalised silica gel and alumina could be applied as a stationary phase in an affinity chromatography technique for the separation and purification of dihydroxybenzenes and the more important biologically active catecholamines.

X-Ray structures and binding properties of molecular clips based on diethoxycarbonyl glycoluril

The crystal structures of two molecular clips derived from diethoxycarbonyl glycoluril were reported. Their unique binding behavior towards hydroquinone, which is different from Nolte's clips (high affinity for resorcinol), has been characterized through 1H NMR and IR. Job-plot analyses provide good evidence of a 1:1 stoichiometry for the complexes.Key words: crystal structure, molecular clips, binding properties