Can terdentate 2,6-bis(1,2,3-triazol-4-yl)pyridines form stable coordination compounds?
TL;DR: The first structurally characterized examples of the 1,2,3-triazole motif employed in a terdentate ligand display enhanced steric freedom and a facile receptivity towards a reversible aquation in the case of an electrogenerated Fe(III) state.
About: This article is published in Chemical Communications.The article was published on 2007-06-26. It has received 237 citations till now. The article focuses on the topics: Aquation & Ligand.
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TL;DR: The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier.
Abstract: The Huisgen 1,3-dipolar cycloaddition reaction of organic azides and alkynes has gained considerable attention in recent years due to the introduction in 2001 of Cu(1) catalysis by Tornoe and Meldal, leading to a major improvement in both rate and regioselectivity of the reaction, as realized independently by the Meldal and the Sharpless laboratories. The great success of the Cu(1) catalyzed reaction is rooted in the fact that it is a virtually quantitative, very robust, insensitive, general, and orthogonal ligation reaction, suitable for even biomolecular ligation and in vivo tagging or as a polymerization reaction for synthesis of long linear polymers. The triazole formed is essentially chemically inert to reactive conditions, e.g. oxidation, reduction, and hydrolysis, and has an intermediate polarity with a dipolar moment of ∼5 D. The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier. In order to understand the reaction in detail, it therefore seems important to spend a moment to consider the structural and mechanistic aspects of the catalysis. The reaction is quite insensitive to reaction conditions as long as Cu(1) is present and may be performed in an aqueous or organic environment both in solution and on solid support.
3,855 citations
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TL;DR: The intention of this review is to provide a detailed analysis of the various supramolecular interactions of triazoles in comparison to established functional units, which may serve as guidelines for further applications.
Abstract: The research on 1,2,3-triazoles has been lively and ever-growing since its stimulation by the advent of click chemistry The attractiveness of 1H-1,2,3-triazoles and their derivatives originates from their unique combination of facile accessibility via click chemistry and truly diverse supramolecular interactions, which enabled myriads of applications in supramolecular and coordination chemistry The nitrogen-rich triazole features a highly polarized carbon atom allowing the complexation of anions by hydrogen and halogen bonding or, in the case of the triazolium salts, via charge-assisted hydrogen and halogen bonds On the other hand, the triazole offers several N-coordination modes including coordination via anionic and cationic nitrogen donors of triazolate and triazolium ions, respectively After CH-deprotonation of the triazole and the triazolium, powerful carbanionic and mesoionic carbene donors, respectively, are available The latter coordination mode even features non-innocent ligand behavior Moreover, these supramolecular interactions can be combined, eg, in ion-pair recognition, preorganization by intramolecular hydrogen bond donation and acceptance, and in bimetallic complexes Ultimately, by clicking two building blocks into place, the triazole emerges as a most versatile functional unit allowing very successful applications, eg, in anion recognition, catalysis, and photochemistry, thus going far beyond the original purpose of click chemistry It is the intention of this review to provide a detailed analysis of the various supramolecular interactions of triazoles in comparison to established functional units, which may serve as guidelines for further applications
626 citations
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TL;DR: This tutorial review will focus on the privileged C-H hydrogen bond donor of the 1,2,3-triazole ring systems as elucidated from anion-binding studies with macrocyclic triazolophanes and other receptors.
Abstract: The supramolecular chemistry of anions provides a means to sense and manipulate anions in their many chemical and biological roles. For this purpose, Click chemistry facilitated the synthetic creation of new receptors and thus, an opportunity to aid in the recent re-examination of CH⋯anion hydrogen bonding. This tutorial review will focus on the privileged C–H hydrogen bond donor of the 1,2,3-triazole ring systems as elucidated from anion-binding studies with macrocyclic triazolophanes and other receptors. Triazolophanes are shape-persistent and planar macrocycles that direct four triazole and four phenylene CH groups into a 3.7 A cavity. They display strong (log K(Cl−) = 7), size-dependent halide binding (Cl− > Br− ≫ F− ≫ I−) and a rich set of binding equilibria. For instance, the too large iodide (4.4 A) can be sandwiched between two pyridyl-based triazolophanes with extreme positive cooperativity. Computational studies verify the triazole's hydrogen bond strength indicating it approaches the traditional NH donors from pyrrole. These examples, those of transport, sensing (e.g., ion-selective electrodes), templation, and versatile synthesis herald the use of triazoles in anion-receptor chemistry.
554 citations
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TL;DR: In this article, the authors present reversible switching between linear and cross-linked supramolecular polymers, where the desired motifs can be conveniently introduced into the low molecular weight monomers, thus avoiding the problems commonly associated with covalently linked polymer backbones, and thus leading to more effective method for switching between different architectures.
Abstract: The topology of a polymer has a significant influence on its properties and functions, both in bulk and in solution. Therefore, the discovery of efficient methods to control polymer topology is very important. [1] The introduction of non-covalent interactions into traditional covalent polymers represents a novel approach for the control of polymer topologies, and has allowed the incorporation of reversible and switchable functionality into different macromolecular architectures. [2] However, this strategy usually requires the integration of specific molecular recognition motifs into polymer chains; such an approach suffers from problems such as the availability of suitable monomers and the poor efficiency of polymerization techniques that are tolerant to functional groups on the polymer. Conversely, supramolecular polymers that are assembled from low molecular weight monomers by non-covalent interactions, such as hydrogen bonding, [3] metal coordination, [4] and host–guest interactions, [5] have demonstrated traditional polymeric properties and are an important resource in the development of stimuliresponsive dynamic materials. [6] Until now, efforts to control the topology of supramolecular polymers have mainly been concerned with the conversion between the large-sized species and their corresponding monomers/oligomers; comparatively little effort has been devoted to the transformation between supramolecular polymers of different topologies. The desired recognition motifs can be conveniently introduced into the low-molecular-weight-monomers, thus avoiding the problems commonly associated with covalently linked polymer backbones, and thus leading to a more effective method for switching between different architectures. Herein, we present reversible switching between linear and cross-linked supramolecular polymers. That biological systems utilize multiple-interaction selfassembly to afford hierarchical and multifunctional systems [7]
389 citations
References
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TL;DR: A least-squares procedure is described for modeling an empirical transmission surface as sampled by multiple symmetry-equivalent and/or azimuth rotation-equ equivalent intensity measurements.
Abstract: A least-squares procedure is described for modeling an empirical transmission surface as sampled by multiple symmetry-equivalent and/or azimuth rotation-equivalent intensity measurements. The fitting functions are sums of real spherical harmonic functions of even order, ylm(− u0) + ylm(u1), 2 ≤ l = 2n ≤ 8. The arguments of the functions are the components of unit direction vectors, −u0 for the reverse incident beam and u1 for the scattered beam, referred to crystal-fixed Cartesian axes. The procedure has been checked by calculations against standard absorption test data.
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TL;DR: In this paper, the authors discuss the properties of strong and moderate hydrogen bonds in biological molecules and include inclusion of inclusion compounds in the graph set theory of graph set theories, which is used in this paper.
Abstract: 1. Brief History 2. Nature and Properties 3. Strong Hydrogen Bonds 4. Moderate Hydrogen Bonds 5. Weak Hydrogen Bonds 6. Cooperativity, Patterns, Graph Set Theory, Liquid Crystals 7. Disorder, Proton Transfer, Isotope Effect, Ferroelectrics, Transitions 8. Water, Water Dimers, Ices, Hydrates 9. Inclusion Compounds 10. Hydrogen Bonding in Biological Molecules 11. Methods
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TL;DR: The C3-symmetric derivative of polytriazolylamines, TBTA, was shown to be a powerful stabilizing ligand for copper(I), protecting it from oxidation and disproportionation, while enhancing its catalytic activity.
1,344 citations
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TL;DR: Polymer synthesis methods now being developed will yield well-defined synthetic macromolecules that are capable of mimicking many of the features of proteins and other natural materials.
Abstract: Several recent conceptual advances, which take advantage of the design criteria and practical techniques of molecular-level control in organic chemistry, allow preparation of well-defined polymers and nanostructured materials Two trends are clear: the realization that synthesis of complex macromolecules poses major challenges and opportunities and the expectation that such materials will exhibit distinctive properties and functions Polymer synthesis methods now being developed will yield well-defined synthetic macromolecules that are capable of mimicking many of the features of proteins (for example, three-dimensional folded structure) and other natural materials These macromolecules have far-reaching potential for the study of molecular-level behavior at interfaces, in thin films, and in solution, while also enabling the development of encapsulation, drug-delivery, and nanoscale-patterning technologies
1,212 citations