Synthesis of 1,2,3-Triazole-4-carboxamide-Containing Foldamers for Sulfate Recognition

Taming Molecular Folding: Anion-Templated Foldamers with Tunable Quaternary Structures

Higher-order foldamers represent a unique class of supramolecules at the forefront of molecular design. Herein we control quaternary folding using a novel approach that combines halogen bonding (XBing) and hydrogen bonding (HBing). We present the first anion-templated double helices induced by halogen bonds (XBs) and stabilized by "hydrogen bond enhanced halogen bonds" (HBeXBs). Our findings demonstrate that the number and orientation of hydrogen bond (HB) and XB donors significantly affect the quaternary structure and guest selectivity of two similar oligomers. This research offers new design elements to engineer foldamers and tailor their quaternary structure for specific guest binding.

Anion Templated Supramolecular Structures Assembled using 1,2,3-Triazole and Triazolium motifs

The use of 1,2,3-triazole and triazolium motifs to construct anion templated supramolecular structures has grown rapidly over the past decade and has enabled a range of complex structures to be synthesised. In this Minireview we highlight the significant advances that have been made in areas such as foldamers, polymers and interlocked systems.

Helical Anion Foldamers in Solution

Using anions to induce molecular structure is a rapidly growing area of dynamic and switchable supramolecular chemistry. The emphasis of this review is on helical anion foldamers in solution, and many of the beautiful complexes described herein are accentuated by their crystal structures. Anion foldamers are defined as single- or multistrand complexes-often helical-that incorporate one or more anions. The review begins by discussing foldamer structure and nomenclature and follows with discourse on the anions which are employed. Recent advances in functional foldamers that bind a single anion are examined, including: induced chirality, stimuli-responsive dynamics, fluorescence changes, organocatalysis, anion transport, and halogen bonding. The review then inspects multianion foldamers, and this section is organized by the number of strands within the foldamer-from single- to triple-strand foldamers. Finally, the review is punctuated by recent hydrogen- and halogen-bonding triple-strand anion foldamers.

Indium- and zinc-catalyzed enantioselective amide propargylation of aldehydes with stannylated allenyl amides

The catalytic enantioselective propargylation of aldehydes with newly prepared stannyl allenyl amides is described. The reaction has been accomplished by using catalytic amounts of indium chloride, zinc chloride, and a chiral BINOL derivative, affording amide-functionalized homopropargyl alcohols in excellent yields and enantioselectivities.

The trans/cis photoisomerization in hydrogen bonded complexes with stability controlled by substituent effects: 3-(6-aminopyridin-3-yl)acrylate case study

The association of aminopyridine-based acrylic acid and its salt was studied by NMR titration experiments. The AA (acceptor, acceptor) hydrogen-bonding pattern present in the salt forms a complex readily with a DD (donor, donor) hydrogen-bonding pattern of the substituted ureas even in polar and competitive environment. The double carbon–carbon bond in the acrylic acid derivative is subjected to photoisomerization. This is dependent on the association with substituted urea derivatives. The substituent in ureas influences the trans/cis isomerization kinetics and position of the photostationary state. Two mechanisms that influence the photoisomerization were proposed. To the best of our knowledge, the trans/cis photoisomerization influenced by the substituent in such a hydrogen-bonding pattern has not observed previously. It was shown that interaction with urea derivatives causes lowering of the trans-to-cis photoreaction rates.

The association of aminopyridine-based acrylic acid and its salt was studied by NMR titration experiments.

Oxoanion binding to a cyclic pseudopeptide containing 1,4-disubstituted 1,2,3-triazole moieties

The converging arrangement of hydrogen bond donors from amide NH and 1,2,3-triazole CH groups enables the described cyclic pseudopeptide to interact with oxoanions in water/DMSO mixtures.

Ruthenium(II) Complexes of Aryl Triazole Foldamers as Receptors for Anions

Ruthenium(II) complexes of oligo(bipyridine-phenyl triazole)s were synthesized as receptors for anions. The receptors, which are partially preorganized through metal-ligand interactions, can fold into a helical conformation to bind chloride, bromide, iodide, or nitrate anions in their inner cavities in acetone or competitive H-bonding media such as 5% water in acetone and DMSO. The short oligomer 1 can sandwich the studied anions with high affinity in acetone. Addition of 5% water to acetone results in overall decreases in the binding strength due to the binding competition from water, but does not change the basic binding mode. The highly competitive H-bonding solvent DMSO causes the receptor-anion interactions to become even weaker. However, in DMSO, the short receptor 1 is still able to bind the halide anions with moderate affinities in a 1:1 stoichiometry, whereas the longer oligomer 2 forms double-strand helices with an anion wrapped inside for all anions investigated so far.

2,4-Bis(4-aryl-1,2,3-triazol-1-yl)pyrrolo[2,3-d]pyrimidines: synthesis and tuning of optical properties by polar substituents

Novel D–π–A–π–D type chromophores – 2,4-bis(4-aryl-1,2,3-triazol-1-yl)pyrrolo[2,3-d]pyrimidines were prepared and their photophysical, electrochemical properties in conjunction with quantum chemical calculations were investigated.

BINOL-linked 1,2,3-triazoles: an unexpected fluorescent sensor with anion–π interaction for iodide ions

BINOL-derived triazoles could be used in organocatalytic silylation and unexpectedly as fluorescent sensors for the recognition of I⁻.

Exploring Anion-Induced Conformational Flexibility and Molecular Switching in a Series of Heteroaryl-Urea Receptors

Anion binding studies of 1,10-phenanthroline- and 2-pyridyl-substituted urea-based receptors reveal that guest-dependent conformations exist in structural variants related to a previously investigated bipyridyl-based receptor. Dynamic conformational switching persists in a monofunctional pyridyl-urea receptor, and the preorganization provided by a phenanthroline-based analogue promotes convergence of anion coordinating groups to a single guest. Despite this predisposition for anion coordination, the conformational flexibility of the bipyridyl-based receptor provides the most selective motif for H₂PO₄^- coordination. Furthermore, the two new phenanthrolyl- and pyridyl-receptors serve as models of the bipyridyl-based receptor, elucidating accurate stepwise association constants for 1:2 host/guest binding by this receptor, and suggest that oxoanions prefer the embrace of a "U" conformation in 1:1 complexes.