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Search for "bridging ligand" in Full Text gives 12 result(s) in Beilstein Journal of Organic Chemistry.
Recent advances in the electrochemical synthesis of organophosphorus compounds
- Babak Kaboudin,
- Milad Behroozi,
- Sepideh Sadighi and
- Fatemeh Asgharzadeh
Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61
- can lead to lower reaction yields because various reaction pathways, including those involving unstable metal-organic intermediates, may become involved. Cyclic voltammetry analysis in both solution and solid phases, using a carbon paste electrode (CPE), revealed that the nature of the bridging ligand
Graphical Abstract
Scheme 1: Electrosynthesis of phenanthridine phosphine oxides.
Scheme 2: Electrosynthesis of 1-aminoalkylphosphine oxides.
Scheme 3: Various electrochemical C–P coupling reactions.
Scheme 4: Electrochemical C–P coupling reaction of indolines.
Scheme 5: Electrochemical C–P coupling reaction of ferrocene.
Scheme 6: Electrochemical C–P coupling reaction of acridines with phosphites.
Scheme 7: Electrochemical C–P coupling reaction of alkenes.
Scheme 8: Electrochemical C–P coupling reaction of arenes in a flow system.
Scheme 9: Electrochemical C–P coupling reaction of heteroarenes.
Scheme 10: Electrochemical C–P coupling reaction of thiazoles.
Scheme 11: Electrochemical C–P coupling reaction of indole derivatives.
Scheme 12: Electrosynthesis of 1-amino phosphonates.
Scheme 13: Electrochemical C–P coupling reaction of aryl and vinyl bromides.
Scheme 14: Electrochemical C–P coupling reaction of phenylpyridine with dialkyl phosphonates in the presence o...
Scheme 15: Electrochemical P–C bond formation of amides.
Scheme 16: Electrochemical synthesis of α-hydroxy phosphine oxides.
Scheme 17: Electrochemical synthesis of π-conjugated phosphonium salts.
Scheme 18: Electrochemical phosphorylation of indoles.
Scheme 19: Electrochemical synthesis of phosphorylated propargyl alcohols.
Scheme 20: Electrochemical synthesis of phosphoramidates.
Scheme 21: Electrochemical reaction of carbazole with diphenylphosphine.
Scheme 22: Electrochemical P–N coupling of carbazole with phosphine oxides.
Scheme 23: Electrochemical P–N coupling of indoles with a trialkyl phosphite.
Scheme 24: Electrochemical synthesis of iminophosphoranes.
Scheme 25: Electrochemical P–O coupling of phenols with dialkyl phosphonate.
Scheme 26: Electrochemical P–O coupling of alcohols with diphenylphosphine.
Scheme 27: Electrochemical P–S coupling of thiols with dialkylphosphines.
Scheme 28: Electrochemical thiophosphorylation of indolizines.
Scheme 29: Electrosynthesis of S-heteroaryl phosphorothioates.
Scheme 30: Electrochemical phosphorylation reactions.
Scheme 31: Electrochemical P–Se formation.
Scheme 32: Electrochemical selenation/halogenation of alkynyl phosphonates.
Scheme 33: Electrochemical enantioselective aryl C–H bond activation.
Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands
- Sergey V. Norkov,
- Anton V. Cherkasov,
- Andrey S. Shavyrin,
- Maxim V. Arsenyev,
- Viacheslav A. Kuropatov and
- Vladimir K. Cherkasov
Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26
- ring seems promising since β-diketones as well as o-quinones are known as chelating ligands. The combination of two different chelating sites in the same molecule should give a bifunctional bridging ligand. Such species are interesting from the viewpoint of assembling of ordered structures in a crystal
Graphical Abstract
Scheme 1: Synthetic pathways for the preparation of o-quinone derivatives with annulated 1,3-dithiole ring.
Figure 1: Active methylene compounds used for the preparation of gem-dithiolates.
Figure 2: Fragment of coordination polymer chain of adduct 8 in the crystal phase. Hydrogen atoms and CF3 gro...
Scheme 2: The tentative pathway for the formation of o-quinone 7 with annulated thiete ring.
Scheme 3: Reactions of o-quinone 6a.
Scheme 4: Stepwise reduction of o-quinones with metals to semiquinonates and catecholates, respectively.
Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore
- Esteban P. Urriolabeitia,
- Pablo Sánchez,
- Alexandra Pop,
- Cristian Silvestru,
- Eduardo Laga,
- Ana I. Jiménez and
- Carlos Cativiela
Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98
- -chelate bonding mode of the ortho-palladated oxazolone and the ability of the carboxylate group to act as a bridging ligand in related complexes, we propose for complexes 3a–f and 3h–j the ‘open-book’ structure shown in Scheme 1. The dimeric open-book structures of 3 can result in the formation of two
Graphical Abstract
Figure 1: (a) General scheme for truxillic acid derivatives; (b) general scheme for symmetric 1,3-diaminotrux...
Figure 2: (a) (Z)-4-Arylidene-2-aryl-5(4H)-oxazolones used for the synthesis of 1,3-diaminotruxillic derivati...
Figure 3: (Z)-4-Arylidene-2((E)-styryl)-5(4H)-oxazolones 2a–j used in this work and overall reaction scheme.
Figure 4: Molecular drawing of the oxazolone 2c.
Scheme 1: Ortho-palladation of oxazolones 2 by treatment with Pd(OAc)2 and different structures obtained for ...
Scheme 2: [2 + 2] Photocycloaddition of cyclopalladated complexes 3 in solution to give the dinuclear cyclobu...
Figure 5: Molecular drawing of cyclobutane ortho-palladated 4a. Ellipsoids are shown at the 50% probability l...
Scheme 3: Release of the 1,3-diaminotruxillic bis-amino ester derivatives 5 by methoxycarbonylation of the Pd...
Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes
- Andrey G. Lvov,
- Max Mörtel,
- Anton V. Yadykov,
- Frank W. Heinemann,
- Valerii Z. Shirinian and
- Marat M. Khusniyarov
Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235
- . Unexpectedly, dinuclear and tetranuclear iron(II) complexes were obtained, which were thoroughly characterized by X-ray crystallography, magnetic measurements, and Mössbauer spectroscopy. The formation of multinuclear complexes is facilitated by two coordination sites of the diarylethene, acting as a bridging
- ligand. The bridging nature of the diarylethene in the complexes prevents photocyclization. Keywords: diarylethene; 2-(imidazol-2-yl)pyridine; iron(II) complex; photochromism; Introduction Transition metal complexes with photoactive ligands are of great interest for advanced photonic applications [1][2
Graphical Abstract
Figure 1: Families of diarylethene-bases ligands with spatial proximity of coordination site (blue) and photo...
Scheme 1: Synthesis of photochromic ligands.
Figure 2: Electronic spectra of diarylethene 6 upon UV irradiation (313 nm, toluene, c = 3.4 × 10−5 M). Inset...
Scheme 2: Reversible photocyclization of ligand 6.
Figure 3: Molecular structure of complexes 8 (top) and 9 (bottom) at 100 K. The H atoms are omitted for clari...
Figure 4: Variable temperature χT product (blue) and χ (green) of 8 (top) and 9 (bottom) measured at an exter...
Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study
- Nikolay O. Chalkov,
- Vladimir K. Cherkasov,
- Gleb A. Abakumov,
- Andrey G. Starikov and
- Viacheslav A. Kuropatov
Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238
- reaction exists in solution as a solvent-separated ion pair with a copper cation. A character of spin-density distribution in a radical anion species leads to the conclusion that the ligand corresponds to type III of the Robin–Day classification. Keywords: acceptor–donor–acceptor triad; bridging ligand
Graphical Abstract
Figure 1: The structural formula of acceptor–donor–acceptor triad 1.
Figure 2: The EPR spectrum of (1·)H in CHCl3, 293 K: a) experimental and b) experimental + D2O.
Scheme 1: Disproportionation of the protonated semiquinones in solution.
Scheme 2: Paramagnetic reduced protonated derivatives of the quinone 2.
Figure 3: The EPR spectrum of (1·)H3 in CHCl3, 293 K: a) experimental, b) simulated, c) experimental + D2O an...
Figure 4: The EPR spectrum of (1·−)H2 THF, 293 K: a) experimental and b) experimental + D2O). Magnified side ...
Figure 5: The well-resolved EPR spectrum of (1·−)H2 in dimethoxyethane (diluted solution), 273 K: a) experime...
Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs
- Arne Klinkebiel,
- Ole Beyer,
- Barbara Malawko and
- Ulrich Lüning
Beilstein J. Org. Chem. 2016, 12, 2267–2273, doi:10.3762/bjoc.12.219
- heterocycles resulting in a bridging ligand for the metal-containing „edges“ of the porous structures. Linkers with more than two ligating sites (carboxylic acids or heterocycles) have also been used successfully. Tri- to hexatopic linkers are also known. The prototype for a trivalent linker is 1,3,5
Graphical Abstract
Figure 1: Steric repulsion between ortho-hydrogen atoms in benzene-1,3,5-tribenzoic acid (BTB) leads to a non...
Figure 2: Mono-substituted TATB linkers 1b–d were successfully employed in the isoreticular syntheses of PCN-...
Figure 3: Retrosynthetic analysis for extended TATBs 2: triple Suzuki coupling between tribromotriazines 3 an...
Figure 4: Synthesis of unsymmetrically substituted 2,4,6-tris(bromoaryl)-1,3,5-triazines 3 from one equivalen...
Figure 5: Synthesis of 4-bromo-3-nitrobenzoyl chloride (5b). Conditions: a) HNO3/H2SO4, 3 h 0 °C, 2 h, room t...
Figure 6: Syntheses of 4-bromo-3-methoxybenzoyl chloride (5c). Conditions: a) Br2, EtOH/HOAc, 30 min, room te...
Figure 7: Triple Suzuki–Miyaura coupling between tribromotriazines 3 and boronic acid 15 and subsequent hydro...
Figure 8: Triple Suzuki coupling between tribromotriazines 3 and boronate 18. Conditions: a) 19a: Pd(PPh3)4, K...
Bi- and trinuclear copper(I) complexes of 1,2,3-triazole-tethered NHC ligands: synthesis, structure, and catalytic properties
- Shaojin Gu,
- Jiehao Du,
- Jingjing Huang,
- Huan Xia,
- Ling Yang,
- Weilin Xu and
- Chunxin Lu
Beilstein J. Org. Chem. 2016, 12, 863–873, doi:10.3762/bjoc.12.85
- 2.024(6)–2.092(6) Å, respectively, which are slightly longer than in dinuclear complexes 3 and 4. Benzimidazolylidene acts as a bridging ligand in a u2 mode and bonded equally to two Cu(I) ions, which is only observed in a few silver(I) and copper(I) complexes. Catalytic application in CuAAC reactions
Graphical Abstract
Scheme 1: Synthesis of copper complexes 2–6.
Figure 1: X-ray diffraction structure of copper(II) complex 2 with thermal ellipsoids drawn at 30% probabilit...
Figure 2: ORTEP the cationic section of [Cu2(L2)2](PF6)2 (3). Thermal ellipsoids are drawn at the 30% probabi...
Figure 3: ORTEP drawing of [Cu2(L3)2](PF6)2 (4). Thermal ellipsoids are drawn at the 30% probability level. H...
Figure 4: ORTEP drawing of [Cu3(L4)3](PF6)3 (5). Thermal ellipsoids are drawn at the 30% probability level. H...
Figure 5: ORTEP drawing of [Cu3(L5)3](PF6)3 (6). Thermal ellipsoids are drawn at the 30% probability level. H...
Figure 6: Yield vs reaction time of different copper complex. The reaction was carried out in acetonitrile-d3...
Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting
- Christian Benkhäuser and
- Arne Lützen
Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79
- strategy has proven to be very successful for the formation of homoleptic complexes through self-recognition [1][2][3][4]. However, self-assembly processes of metallosupramolecular aggregates that integrate more than one type of bridging ligand and/or one type of metal ion into an assembly are even more
Graphical Abstract
Scheme 1: Schematic representation of self-sorting effects in metallosupramolecular self-assembly processes.
Scheme 2: Schematic representation of our approach to discrete heteroleptic oligonuclear metallosupramolecula...
Figure 1: Tröger’s base-derived bis(phenanthroline) ligand (rac)-1 and bis(bipyridine) ligand 2.
Scheme 3: Synthesis of chiral bis(phenanthroline) ligand (rac)-1 from 3.
Scheme 4: Synthesis of bis(bipyridine) ligand 2 from 2-aminopyridine (4).
Figure 2: NMR spectra (500.1 MHz in DMSO-d6 at 295 K) of free ligands b) (rac)-1 and c) 2; 1:1 mixtures of li...
Figure 3: ESI mass spectrum (positive ion mode) of a 1:1:2 mixture of (rac)-1, 2, and CuBF4 sprayed from a 10...
Scheme 5: Summary of the coordination behavior of the two ligands 1 and 2 and their equimolar mixture towards...
Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition
- Regina Berg and
- Bernd F. Straub
Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308
- reported by Pérez-Castro [139] and Tanaka [140]. It has been proposed that the iodide ion can act as μ2-bridging ligand so that polynuclear copper(I) acetylide complexes are formed, which are less active in the catalytic cycle for the formation of 5H-1,2,3-triazoles. Fokin suggests that under certain
Graphical Abstract
Scheme 1: Exemplary 1,3-dipolar cycloaddition of phenylacetylene with phenyl azide [6].
Scheme 2: CuAAC reaction of benzyl azide with (prop-2-yn-1-yloxy)benzene [12].
Scheme 3: Bioconjugation reaction of capsid-bound azide groups with alkynyl-functionalized dye molecules (cow...
Figure 1: Tris(triazolylmethyl)amine ligands for CuAAC applications in bioorganic chemistry: TBTA = tris[(1-b...
Figure 2: Derivatives of 2,2’-bipyridine and 1,10-phenanthroline, commonly used ligands in CuAAC reactions un...
Scheme 4: CuAAC reaction with copper(II) precursor salt and rate-accelerating monodentate phosphoramidite lig...
Scheme 5: Synthesis of 1-(adamant-1-yl)-1H-1,2,3-triazol-4-ylcarbonyl-Phe-Gly-OH by solid-supported Click cat...
Scheme 6: CuAAC reaction with re-usable copper(I)-tren catalyst [129].
Scheme 7: CuAAC test reaction with chlorido[tris(1-benzyl-1H-1,2,3-triazol-4-yl)methanol-κ3N3]copper(I) and a...
Scheme 8: CuAAC model reaction with [Cu2(μ-TBTA-κ4N2,N3,N3’,N3’’)2][BF4]2 [131].
Scheme 9: Application of a (2-aminoarenethiolato)copper(I) complex as homogeneous catalyst for the CuAAC test...
Scheme 10: Application of [CuBr(PPh3)3] as homogeneous catalyst for the CuAAC test reaction of benzyl azide wi...
Figure 3: Phosphinite and phosphonite copper(I) complexes presented by Díez-González [144].
Scheme 11: Effect of additives on the CuAAC test reaction with [(SIMes)CuCl] [149].
Scheme 12: Initiation of the catalytic cycle by formation of the copper acetylide intermediate from [(ICy)2Cu]...
Scheme 13: Early mechanistic proposal by Sharpless [12,42].
Scheme 14: Chemoselective synthesis of a 5-iodo-1,4-disubstituted 1,2,3-triazole [156].
Scheme 15: Mechanistic proposals for the copper-catalyzed azide–iodoalkyne cycloaddition [156].
Scheme 16: 1,3-Dipolar cycloaddition of 3-hexyne catalyzed by [(SIMes)CuBr] [146].
Scheme 17: Mechanistic picture for the cycloaddition of internal alkynes catalyzed by NHC-copper(I) complexes ...
Scheme 18: Catalytic cycle of the CuAAC reaction on the basis of the proposed mechanistic scheme by Fokin and ...
Figure 4: Schematic representation of the single crystal X-ray structures of copper(I) acetylide complexes [Cu...
Figure 5: Acetylide-bridged dicopper complexes with tris(heteroarylmethyl)amine ligand(s) as key intermediate...
Scheme 19: Off-cycle equilibrium between unreactive polymeric copper(I) acetylide species (right) and reactive...
Figure 6: Categories of tris(heteroarylmethyl)amine ligands regarding their binding ability to copper(I) ions ...
Scheme 20: Mechanistic scheme for ligand-accelerated catalysis with tripodal tris(heteroarylmethyl)amine ligan...
Scheme 21: Synthesis of supposed intermediates in the CuAAC’s catalytic cycle [164,187].
Figure 7: Tetranuclear copper acetylide complexes as reported by Weiss (left) [176] and Tasker (middle) [185] and model...
Figure 8: Gibbs free energy diagram for the computed mechanistic pathway of the CuAAC reaction starting from ...
Figure 9: Energy diagram by Ahlquist and Fokin [125].
Scheme 22: Mechanistic proposal for the CuAAC reaction based on DFT calculations by Fokin [125] and our group [186] ([Cu...
Figure 10: ORTEP plot [202,203] of the X-ray powder diffraction crystal structure of (phenylethynyl)copper(I) [(PhC≡CCu)...
Scheme 23: Synthesis of [(PhC≡CCu)2]n as co-product in the Glaser coupling of phenylacetylene in the presence ...
Scheme 24: Mechanistic explanation for the isotopic enrichment in the product triazolide in the presence of th...
Scheme 25: Homogeneous CuAAC catalysis with a bistriazolylidene dicopper complex (0.5 mol %) and comparison wi...
True and masked three-coordinate T-shaped platinum(II) intermediates
- Manuel A. Ortuño,
- Salvador Conejero and
- Agustí Lledós
Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153
Graphical Abstract
Figure 1: Qualitative orbital diagram for a d8 metal in ML4 square-planar and ML3 T-shaped complexes.
Figure 2: Walsh diagram for the d-block of a d8 ML3 complex upon bending of one L–M–L angle.
Figure 3: Neutral Y-shaped Pt complex Y1 [15]. Angles are given in degrees.
Figure 4: General classification of T-shaped Pt(II) structures according to the fourth coordination site.
Figure 5: Hydride, boryl and borylene true T-shaped Pt(II) complexes.
Figure 6: NHC-based true T-shaped Pt(II) complexes.
Figure 7: Phosphine-based agostic T-shaped Pt(II) complexes. Compounds in brackets correspond with hydrido–al...
Figure 8: Phenylpyridine and NHC-based agostic T-shaped Pt(II) complexes.
Figure 9: Counteranion coordination in T-shaped Pt(II) complexes.
Figure 10: Phosphine-based solvento Pt(II) complexes.
Figure 11: Nitrogen-based solvento Pt(II) complexes.
Figure 12: Pincer-based solvento Pt(II) complexes.
Figure 13: Structure of the QM/MM optimized cisplatin–protein adduct [94].
Figure 14: NMR coupling constants used for the characterization of three-coordinate Pt(II) species.
Figure 15: The chemical formula of the complexes discussed in Table 2.
Scheme 1: Halogen abstraction from 1.
Scheme 2: Halogen abstraction from 2 forming the dicationic complex T3 [22].
Scheme 3: Hydrogenation of complexes A5a and A5b [39].
Scheme 4: Hydrogenation of complexes 3 and A5c [40].
Scheme 5: Intermolecular C–H bond activation from T5a [28].
Scheme 6: Protonation of complexes 4 [35,36].
Scheme 7: Cyclometalation of 5 [43].
Scheme 8: Protonation of 6.
Scheme 9: Reductive elimination of ethane from 7.
Scheme 10: Reductive elimination of methane from six-coordinate Pt(IV) complexes.
Scheme 11: Proposed dissociative mechanism for the fluxional motion of dmphen in [Pt(Me)(dmphen)(PR3)]+ comple...
Figure 16: Feasible interactions for unsaturated intermediates 11b (left) and 12b (right) during fluxional mot...
Scheme 12: Halogen abstraction from 13a,b and subsequent cyclometalation to yield complexes A5a,b [39].
Scheme 13: Proposed mechanism for the acid-catalyzed cyclometalation of 14 via intermediate 15 [41].
Scheme 14: Proposed mechanism for the formation of 19 [102].
Scheme 15: Cyclometalation of 20 via thioether dissociation [117].
Figure 17: Gibbs energy profile (in chloroform solvent) for the cyclometalation of 23 [120].
Scheme 16: Coordination of tmtu to 29 and subsequent C–H bond activation via three-coordinate species 31 and 32...
Scheme 17: Cyclometalation process of NHC-based Pt(II) complexes [28,44].
Scheme 18: Cyclometalation process of complex A9 [43].
Scheme 19: “Rollover” reaction of 38 and subsequent oligomerization [123].
Scheme 20: Proposed mechanism for the formation of cyclometalated species 44 [124].
Scheme 21: Self-assembling process of 45 by “rollover” reaction [126].
Scheme 22: “Rollover” reaction of A9. Energies (solvent) in kcal mol−1 [127].
Scheme 23: Proposed mechanisms for the “rollover” cyclometalation of 52 in gas-phase ion-molecule reactions [128].
Scheme 24: β-H elimination and 1,2-insertion equilibrium involving A1d and the subsequent generation of 57 [35].
Scheme 25: Proposed mechanism for thermolysis of 7b and 7c in benzene-d6 and cyclohexane-d12 solvents [101].
Scheme 26: β-H elimination process of A11a [28].
Scheme 27: Intermolecular C–H bond activation from 62 [95].
Scheme 28: Reductive elimination of methane from 65 followed by CD3CN coordination or C–D bond-activation proc...
Figure 18: DFT-optimized structures describing the κ2 (69, left) and κ3 (69’, right) coordination modes of [Pt...
Scheme 29: Intermolecular arene C–H bond activation from NHC-based complexes [28].
Figure 19: Energy profiles (in benzene solvent) for the benzene C–H bond activation from A11a, A11b, T5a and T...
Scheme 30: Intermolecular arene C–H bond activation from PNP-based complex 71 [12].
Scheme 31: Intermolecular C–H bond-activation by gas-phase ion-molecule reactions of 74 [7,142].
Scheme 32: Dihydrogen activation through complexes A5a, A5b [39], A5c [40] and S1a [54].
Scheme 33: Dihydrogen activation through complexes A7 and 16 [41]. For a: see Scheme 13.
Scheme 34: Br2 and I2 bond activations through complexes A11a and T5a [143].
Scheme 35: Detection and isolation of the Pt(III) complex 81a [143].
Scheme 36: Cl2 bond activation through complexes 82 and 83 [144].
Scheme 37: cis–trans Isomerization mechanism of the solvento Pt(II) complexes S5 [2,61].
Figure 20: Energy profiles for the isomerization of complexes [Pt(R)(PMe3)2(NCMe)]+ where R means Me (85a, red...
Figure 21: DFT-optimized structure of intermediate 86 [62]. Bond distances in angstrom and angles in degrees.
Scheme 38: Proposed dissociative ligand-substitution mechanism of cis-[Pt(R)2S2] complexes (87) [117].
Scheme 39: Proposed mechanisms for the ligand substitution of the dinuclear species 91 [146].
Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties
- Antonio Avellaneda,
- Courtney A. Hollis,
- Xin He and
- Christopher J. Sumby
Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7
- tetradentate bridge [18][19]. Hexa(4-pyridyl)[3]radialene also acts as a bridging ligand in a 3-D coordination polymer with AgClO4 [20], while isomorphous 6,3-connected 2-D coordination polymers were obtained when hexakis(4-cyanophenyl)[3]radialene was reacted with AgPF6 and AgClO4 [21]. Anion–π interactions
Graphical Abstract
Figure 1: The structures of a) the parent [3]-, [4]-, [5]-, and [6]dendralenes and b) the corresponding radia...
Scheme 1: Synthesis of (a) hexakis(3-cyanophenyl)[3]radialene (2) and (b) hexakis(3,4-dicyanophenyl)[3]radial...
Figure 2: A perspective view of the asymmetric unit of 3.
Figure 3: (a) UV–visible (bold line) and fluorescence (dashed line) spectra of 1, 2, hexa(2-pyridyl)[3]radial...
Molecular recognition of organic ammonium ions in solution using synthetic receptors
- Andreas Späth and
- Burkhard König
Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32
Graphical Abstract
Figure 1: Biologically important amines and quaternary ammonium salts: histamine (1), dopamine (2) and acetyl...
Figure 2: Crown ether 18-crown-6.
Figure 3: Conformations of 18-crown-6 (4) in solvents of different polarity.
Figure 4: Binding topologies of the ammonium ion depending on the crown ring size.
Figure 5: A “pseudorotaxane” structure consisting of 24-crown-8 and a secondary ammonium ion (5); R = Ph.
Figure 6: Typical examples of azacrown ethers, cryptands and related aza macrocycles.
Figure 7: Binding of ammonium to azacrown ethers and cryptands [111-113].
Figure 8: A 19-crown-6-ether with decalino blocking groups (11) and a thiazole-dibenzo-18-crown-6-ether (12).
Figure 9: 1,3-Bis(6-oxopyridazin-1-yl)propane derivatives 13 and 14 by Campayo et al.
Figure 10: Fluorescent azacrown-PET-sensors based on coumarin.
Figure 11: Two different pyridino-cryptands (17 and 18) compared to a pyridino-crown (19); chiral ammonium ion...
Figure 12: Pyridino-18-crown-6 ligand (21), a similar acridino-18-crown-6 ligand (22) and a structurally relat...
Figure 13: Ciral pyridine-azacrown ether receptors 24.
Figure 14: Chiral 15-crown-5 receptors 26 and an analogue 18-crown-6 ligand 27 derived from amino alcohols.
Figure 15: C2-symmetric chiral 18-crown-6 amino alcohol derivatives 28 and related macrocycles.
Figure 16: Macrocycles with diamide-diester groups (30).
Figure 17: C2-symmetric chiral aza-18-crown-6 ethers (31) with phenethylamine residues.
Figure 18: Chiral C-pivot p-methoxy-phenoxy-lariat ethers.
Figure 19: Chiral lariat crown ether 34.
Figure 20: Sucrose-based chiral crown ether receptors 36.
Figure 21: Permethylated fructooligosaccharide 37 showing induced-fit chiral recognition.
Figure 22: Biphenanthryl-18-crown-6 derivative 38.
Figure 23: Chiral lariat crown ethers derived from binol by Fuji et al.
Figure 24: Chiral phenolic crown ether 41 with “aryl chiral barriers” and guest amines.
Figure 25: Chiral bis-crown receptor 43 with a meso-ternaphthalene backbone.
Figure 26: Chromogenic pH-dependent bis-crown chemosensor 44 for diamines.
Figure 27: Triamine guests for binding to receptor 44.
Figure 28: Chiral bis-crown phenolphthalein chemosensors 46.
Figure 29: Crown ether amino acid 47.
Figure 30: Luminescent receptor 48 for bis-alkylammonium guests.
Figure 31: Luminescent CEAA (49a), a bis-CEAA receptor for amino acids (49b) and the structure of lysine bindi...
Figure 32: Luminescent CEAA tripeptide for binding small peptides.
Figure 33: Bis crown ether 51a self assembles co-operatively with C60-ammonium ion 51b.
Figure 34: Triptycene-based macrotricyclic dibenzo-[24]-crown-8 ether host 52 and guests.
Figure 35: Copper imido diacetic acid azacrown receptor 53a and the suggested His-Lys binding motif; a copper ...
Figure 36: Urea (54) and thiourea (55) benzo crown receptor for transport and extraction of amino acids.
Figure 37: Crown pyryliums ion receptors 56 for amino acids.
Figure 38: Ditopic sulfonamide bridged crown ether receptor 57.
Figure 39: Luminescent peptide receptor 58.
Figure 40: Luminescent receptor 59 for the detection of D-glucosamine hydrochloride in water/ethanol and lumin...
Figure 41: Guanidinium azacrown receptor 61 for simple amino acids and ditopic receptor 62 with crown ether an...
Figure 42: Chiral bicyclic guanidinium azacrown receptor 63 and similar receptor 64 for the enantioselective t...
Figure 43: Receptors for zwitterionic species based on luminescent CEAAs.
Figure 44: 1,10-Azacrown ethers with sugar podand arms and the anticancer agent busulfan.
Figure 45: Benzo-18-crown-6 modified β-cyclodextrin 69 and β-cyclodextrin functionalized with diaza-18-crown-6...
Figure 46: Receptors for colorimetric detection of primary and secondary ammonium ions.
Figure 47: Porphyrine-crown-receptors 72.
Figure 48: Porphyrin-crown ether conjugate 73 and fullerene-ammonium ion guest 74.
Figure 49: Calix[4]arene (75a), homooxocalix[4]arene (75b) and resorcin[4]arene (75c) compared (R = H, alkyl c...
Figure 50: Calix[4]arene and ammonium ion guest (R = H, alkyl, OAcyl etc.), possible binding sites; A: co-ordi...
Figure 51: Typical guests for studies with calixarenes and related molecules.
Figure 52: Lower rim modified p-tert-butylcalix[5]arenes 82.
Figure 53: The first example of a water soluble calixarene.
Figure 54: Sulfonated water soluble calix[n]arenes that bind ammonium ions.
Figure 55: Displacement assay for acetylcholine (3) with a sulfonato-calix[6]arene (84b).
Figure 56: Amino acid inclusion in p-sulfonatocalix[4]arene (84a).
Figure 57: Calixarene receptor family 86 with upper and lower rim functionalization.
Figure 58: Calix[6]arenes 87 with one carboxylic acid functionality.
Figure 59: Sulfonated calix[n]arenes with mono-substitution at the lower rim systematically studied on their r...
Figure 60: Cyclotetrachromotropylene host (91) and its binding to lysine (81c).
Figure 61: Calixarenes 92 and 93 with phosphonic acids groups.
Figure 62: Calix[4]arene tetraphosphonic acid (94a) and a double bridged analogue (94b).
Figure 63: Calix[4]arene tetraphosphonic acid ester (92c) for surface recognition experiments.
Figure 64: Calixarene receptors 95 with α-aminophosphonate groups.
Figure 65: A bridged homocalix[3]arene 95 and a distally bridged homocalix[4]crown 96.
Figure 66: Homocalix[3]arene ammonium ion receptor 97a and the Reichardt’s dye (97b) for colorimetric assays.
Figure 67: Chromogenic diazo-bridged calix[4]arene 98.
Figure 68: Calixarene receptor 99 by Huang et al.
Figure 69: Calixarenes 100 reported by Parisi et al.
Figure 70: Guest molecules for inclusion in calixarenes 100: DAP × 2 HCl (101a), APA (101b) and Lys-OMe × 2 HC...
Figure 71: Different N-linked peptido-calixarenes open and with glycol chain bridges.
Figure 72: (S)-1,1′-Bi-2-naphthol calixarene derivative 104 published by Kubo et al.
Figure 73: A chiral ammonium-ion receptor 105 based on the calix[4]arene skeleton.
Figure 74: R-/S-phenylalaninol functionalized calix[6]arenes 106a and 106b.
Figure 75: Capped homocalix[3]arene ammonium ion receptor 107.
Figure 76: Two C3 symmetric capped calix[6]arenes 108 and 109.
Figure 77: Phosphorous-containing rigidified calix[6]arene 110.
Figure 78: Calix[6]azacryptand 111.
Figure 79: Further substituted calix[6]azacryptands 112.
Figure 80: Resorcin[4]arene (75c) and the cavitands (113).
Figure 81: Tetrasulfonatomethylcalix[4]resorcinarene (114).
Figure 82: Resorcin[4]arenes (115a/b) and pyrogallo[4]arenes (115c, 116).
Figure 83: Displacement assay for acetylcholine (3) with tetracyanoresorcin[4]arene (117).
Figure 84: Tetramethoxy resorcinarene mono-crown-5 (118).
Figure 85: Components of a resorcinarene based displacement assay for ammonium ions.
Figure 86: Chiral basket resorcin[4]arenas 121.
Figure 87: Resorcinarenes with deeper cavitand structure (122).
Figure 88: Resorcinarene with partially open deeper cavitand structure (123).
Figure 89: Water-stabilized deep cavitands with partially structure (124, 125).
Figure 90: Charged cavitands 126 for tetralkylammonium ions.
Figure 91: Ditopic calix[4]arene receptor 127 capped with glycol chains.
Figure 92: A calix[5]arene dimer for diammonium salt recognition.
Figure 93: Calixarene parts 92c and 129 for the formation molecular capsules.
Figure 94: Encapsulation of a quaternary ammonium cation by two resorcin[4]arene molecules (NMe4+@[75c]2 × Cl−...
Figure 95: Encapsulation of a quaternary ammonium cation by six resorcin[4]arene molecules (NMe3D+@[130]6 × Cl−...
Figure 96: Structure and schematic of cucurbit[6]uril (CB[6], 131a).
Figure 97: Cyclohexanocucurbit[6]uril (CB′[6], 132) and the guest molecule spermine (133).
Figure 98: α,α,δ,δ-Tetramethylcucurbit[6]uril (134).
Figure 99: Structure of the cucurbituril-phthalhydrazide analogue 135.
Figure 100: Organic cavities for the displacement assay for amine differentiation.
Figure 101: Displacement assay methodology for diammonium- and related guests involving cucurbiturils and some ...
Figure 102: Nor-seco-Cucurbituril (±)-bis-ns-CB[6] (140) and guest molecules.
Figure 103: The cucurbit[6]uril based complexes 141 for chiral discrimination.
Figure 104: Cucurbit[7]uril (131c) and its ferrocene guests (142) opposed.
Figure 105: Cucurbit[7]uril (131c) guest inclusion and representative guests.
Figure 106: Cucurbit[7]uril (131c) binding to succinylcholine (145) and different bis-ammonium and bis-phosphon...
Figure 107: Paraquat-cucurbit[8]uril complex 149.
Figure 108: Gluconuril-based ammonium receptors 150.
Figure 109: Examples of clefts (151a), tweezers (151b, 151c, 151d) and clips (151e).
Figure 110: Kemp’s triacid (152a), on example of Rebek’s receptors (152b) and guests.
Figure 111: Amino acid receptor (154) by Rebek et al.
Figure 112: Hexagonal lattice designed hosts by Bell et al.
Figure 113: Bell’s amidinium receptor (156) and the amidinium ion (157).
Figure 114: Aromatic phosphonic acids.
Figure 115: Xylene phosphonates 159 and 160a/b for recognition of amines and amino alcohols.
Figure 116: Bisphosphonate recognition motif 161 for a colorimetric assay with alizarin complexone (163) for ca...
Figure 117: Bisphosphonate/phosphate clip 164 and bisphosphonate cleft 165.
Figure 118: N-Methylpyrazine 166a, N-methylnicotinamide iodide (166b) and NAD+ (166c).
Figure 119: Bisphosphate cavitands.
Figure 120: Bisphosphonate 167 of Schrader and Finocchiaro.
Figure 121: Tweezer 168 for noradrenaline (80b).
Figure 122: Different tripods and heparin (170).
Figure 123: Squaramide based receptors 172.
Figure 124: Cage like NH4+ receptor 173 of Kim et al.
Figure 125: Ammonium receptors 174 of Chin et al.
Figure 126: 2-Oxazolin-based ammonium receptors 175a–d and 176 by Ahn et al.
Figure 127: Racemic guest molecules 177.
Figure 128: Tripods based on a imidazole containing macrocycle (178) and the guest molecules employed in the st...
Figure 129: Ammonium ion receptor 180.
Figure 130: Tetraoxa[3.3.3.3]paracyclophanes 181 and a cyclophanic tetraester (182).
Figure 131: Peptidic bridged paraquat-cyclophane.
Figure 132: Shape-selective noradrenaline host.
Figure 133: Receptor 185 for binding of noradrenaline on surface layers from Schrader et al.
Figure 134: Tetraphosphonate receptor for binding of noradrenaline.
Figure 135: Tetraphosphonate 187 of Schrader and Finocchiaro.
Figure 136: Zinc-Porphyrin ammonium-ion receptors 188 and 189 of Mizutani et al.
Figure 137: Zinc porphyrin receptor 190.
Figure 138: Zinc porphyrin receptors 191 capable of amino acid binding.
Figure 139: Zinc-porphyrins with amino acid side chains for stereoinduction.
Figure 140: Bis-zinc-bis-porphyrin based on Tröger’s base 193.
Figure 141: BINAP-zinc-prophyrin derivative 194 and it’s guests.
Figure 142: Bisaryl-linked-zinc-porphyrin receptors.
Figure 143: Bis-zinc-porphyrin 199 for diamine recognition and guests.
Figure 144: Bis-zinc-porphyrin crown ether 201.
Figure 145: Bis-zinc-porphyrin 202 for stereodiscrimination (L = large substituent; S = small substituent).
Figure 146: Bis-zinc-porphyrin[3]rotaxane and its copper complex and guests.
Figure 147: Dien-bipyridyl ligand 206 for co-ordination of two metal atoms.
Figure 148: The ligand and corresponding tetradentate co-complex 207 serving as enantioselective receptor for a...
Figure 149: Bis(oxazoline)–copper(II) complex 208 for the recognition of amino acids in aqueous solution.
Figure 150: Zinc-salen-complexes 209 for the recognition tertiary amines.
Figure 151: Bis(oxazoline)–copper(II) 211 for the recognition of amino acids in aqueous solution.
Figure 152: Zn(II)-complex of a C2 terpyridine crown ether.
Figure 153: Displacement assay and receptor for aspartate over glutamate.
Figure 154: Chiral complex 214 for a colorimetric displacement assay for amino acids.
Figure 155: Metal complex receptor 215 with tripeptide side arms.
Figure 156: A sandwich complex 216 and its displaceable dye 217.
Figure 157: Lanthanide complexes 218–220 for amino acid recognition.
Figure 158: Nonactin (221), valinomycin (222) and vancomycin (223).
Figure 159: Monesin (224a) and a chiral analogue for enantiodiscrimination of ammonium guests (224b).
Figure 160: Chiral podands (226) compared to pentaglyme-dimethylether (225) and 18-crown-6 (4).
Figure 161: Lasalocid A (228).
Figure 162: Lasalocid derivatives (230) of Sessler et al.
Figure 163: The Coporphyrin I tetraanion (231).
Figure 164: Linear and cyclic peptides for ammonium ion recognition.
Figure 165: Cyclic and bicyclic depsipeptides for ammonium ion recognition.
Figure 166: α-Cyclodextrin (136a) and novocaine (236).
Figure 167: Helical diol receptor 237 by Reetz and Sostmann.
Figure 168: Ammonium binding spherand by Cram et al. (238a) and the cyclic[6]metaphenylacetylene 238b in compar...
Figure 169: Receptor for peptide backbone and ammonium binding (239).
Figure 170: Anion sensor principle with 3-hydroxy-2-naphthanilide of Jiang et al.
Figure 171: 7-bromo-3-hydroxy-N-(2-hydroxyphenyl)naphthalene 2-carboxamide (241) and its amine binding.
Figure 172: Naturally occurring catechins with affinity to quaternary ammonium ions.
Figure 173: Spiropyran (244) and merocyanine form (244a) of the amino acid receptors of Fuji et al.
Figure 174: Coumarin aldehyde (245) and its iminium species with amino acid bound (245a) by Glass et al.
Figure 175: Coumarin aldehyde appended with boronic acid.
Figure 176: Quinolone aldehyde dimers by Glass et al.
Figure 177: Chromogenic ammonium ion receptors with trifluoroacetophenone recognition motifs.
Figure 178: Chromogenic ammonium ion receptor with trifluoroacetophenone recognition motif bound on different m...
