Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• closely related tweezers based on a 2,6-bis(oxazolinyl)pyridine (Pybox) ligand with two 4-nitrophenylurea substituents as anion receptor 24 (Figure 14b) [56]. This ligand presents a “W” to “U”-shaped conformational change upon metal coordination similar to terpyridine but displays additional chirality

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• spherical halides [10]. The key to hydrogen bonding of the halide anion resides in the polarized N–H bonds of these (thio)urea units, which have since served as a benchmark in the design and development of anion receptor catalysts [12][13][14]. Consequently, other synthetic anion receptors have been

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• −223 kJ/mol ([12 + 2Iexo]2−) that show a stronger affinity of 12 towards anions compared to 22. Conclusion In conclusion, we have shown that the pyridine[4]arene dimer, which until recently was considered to be an anion receptor, can bind also cationic guests. The Me4N+ cation was observed to bind to

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• steric restriction for bigger anionic species such as sulfate and acetate and leads their binding to the outside of the cavity. 2.6. Multi-1,2,3-triazolium macrocycles As a matter of fact, a cyclic host framework incorporating multiple charged moieties may create a potent anion receptor that functions in

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• organic chemistry [13][14][15][16][17][18][19][20][21][22][23]. Anion-receptor biomimetics aimed at developing synthetic analogs of the natural compounds that offer a deeper understanding of a number of biological processes. The design of anion receptors is quite a challenge for several reasons. The

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• -tolylurea (33) reported by Swinburne and Steed in 2009 [45]. This compound was found to bind anions individually and as part of a tripodal anion receptor. In contrast to solution synthesis in dichloromethane for 12 hours, the mechanochemical solvent-free coupling of 3-aminopyridine and 4-methylphenyl

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• has enriched the field of anion receptor chemistry with a wide array of design strategies [15][16][17][18][19]. Among the various analytical techniques, colorimetry has drawn significant attention among chemists for its rapid response rate, low cost, easy method and high selectivity [20][21][22][23

Co-solvation effect on the binding mode of the α-mangostin/β-cyclodextrin inclusion complex

• Chompoonut Rungnim,
• Sarunya Phunpee,
• Manaschai Kunaseth,
• Supawadee Namuangruk,
• Kanin Rungsardthong,
• Thanyada Rungrotmongkol and
• Uracha Ruktanonchai

Beilstein J. Org. Chem. 2015, 11, 2306–2317, doi:10.3762/bjoc.11.251

• anion affinity and selectivity of a neutral anion receptor, bis(cyclopeptide) [17]. Molecular dynamics (MD) simulations can give important insights into the energetics of structural interactions. The hydrated structure of β-CD in aqueous solution [18] and those showing host–guest interactions between

Macrocyclic bis(ureas) as ligands for anion complexation

• Claudia Kretschmer,
• Gertrud Dittmann and
• Johannes Beck

Beilstein J. Org. Chem. 2014, 10, 1834–1839, doi:10.3762/bjoc.10.193

• proven to be an excellent anion receptor. The ability to form two directional hydrogen bonds through the highly polarized N−H groups towards different kinds of anions allows for building particular molecular arrangements. Incorporation of two or three urea groups into one molecular entity enables the

NMR studies of anion-induced conformational changes in diindolylureas and diindolylthioureas

• Damjan Makuc,
• Jennifer R. Hiscock,
• Mark E. Light,
• Philip A. Gale and
• Janez Plavec

Beilstein J. Org. Chem. 2011, 7, 1205–1214, doi:10.3762/bjoc.7.140

• along the C7–N7α bonds and the syn–syn conformer was preferred for anion–receptor complexes. The conformational changes upon anion binding are in good agreement with energetic preferences established by ab initio calculations. Keywords: anion recognition; conformation analysis; host–guest systems; NMR

• extensively employed in synthetic anion receptors comprising groups such as amides, pyrroles, indoles, ureas and triazoles, as well as in ammonium, guanidinium and imidazolium moieties used as hydrogen bond donors [16][17][18][19][20][21][22][23]. Amongst neutral anion receptor systems, indole and related

• anion–receptor interaction were found to be H1, H6 and H7α. Only minor ΔδH7α and negligible differences of δH1 and δH6 were observed in the presence of chloride anions (Figure 2a and Figure 2b). The very weak interactions between chloride and 1 could be due to competing interactions of the polar DMSO

Anion receptors containing thiazine-1,1-dioxide heterocycles as hydrogen bond donors

• Hong-Bo Wang,
• James A. Wisner and
• Michael C. Jennings

Beilstein J. Org. Chem. 2010, 6, No. 50, doi:10.3762/bjoc.6.50

• using straightforward synthetic methods and inexpensive materials and reagents. Herein, we describe an illustrative synthesis of two anion hosts incorporating these heterocycles and compare their binding affinities with some common anionic guests to that of an analogous benzene disulfonamide anion

• receptor. Results and Discussion The two receptor structures 1 and 2 (Figure 2) were chosen with the intent of evaluating their efficacy in comparison to the known anion host N,N′-diphenyl-1,3-disulfonamidobenzene 3 (Figure 2) [21]. Originally investigated for anion recognition by Crabtree and coworkers, 3

Synthesis of indolo[3,2-b]carbazole-based new colorimetric receptor for anions: A unique color change for fluoride ions

• Ajit Kumar Mahapatra,
• Giridhari Hazra and
• Prithidipa Sahoo

Beilstein J. Org. Chem. 2010, 6, No. 12, doi:10.3762/bjoc.6.12

• supramolecular chemistry [1][2]. Most of the synthetic chemosensors generally involve covalent linking of an optical-signaling chromophoric fragment to a neutral anion receptor containing urea [3], thiourea [4], amide [5], phenol [6][7], or pyrrole [8] subunits, which can provide one or more H-bond donor sites

Structural studies on encapsulation of tetrahedral and octahedral anions by a protonated octaaminocryptand cage

• I. Ravikumar,
• P. S. Lakshminarayanan,
• E. Suresh and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2009, 5, No. 41, doi:10.3762/bjoc.5.41

• . Keywords: anion receptor; cryptand; molecular recognition; proton cage; Introduction In recent years considerable efforts have been made in elucidating the coordination chemistry of anions because of their vital roles in biological systems [1], medicine [2], catalysis [3], and environmental issues [4