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Search for "cysteine" in Full Text gives 132 result(s) in Beilstein Journal of Organic Chemistry.
Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes
- Jan-Christoph Kehr,
- Douglas Gatte Picchi and
- Elke Dittmann
Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191
- -type monooxygenases encoded by the cluster, HctG or HctH, to 2,3-dihydroxyisovaleric acid. Two other NRPS modules contain all the required domains for adenylation and heterocyclization of cysteine, and an FMN-dependent oxidase domain, which is likely involved in thiazole ring formation. The cluster
- multidrug resistance [59]. The patellamide gene cluster consists of seven genes, expression of which in E. coli leads to the production of the peptides [59]. Heterocyclization of serine, cysteine and threonine, respectively is catalyzed by the heterocyclase PatD [60]. In contrast to other heterocyclases
- of bacteria. The characteristic feature of the group is lanthionine bridges, which are formed by dehydration of serine or threonine followed by intramolecular addition of cysteine thiols to the resulting dehydro amino acids. Lantipeptides exhibit a variety of bioactivities, in particular
Graphical Abstract
Figure 1: Cyanobacteria proliferate in diverse habitats. A) Bloom-forming freshwater cyanobacteria of the gen...
Figure 2: Schematic representation of enzymatic domains in A) nonribosomal peptide synthetases (NRPS); B) pol...
Figure 3: Structures of NRPS and PKS products in freshwater cyanobacteria.
Figure 4: A) Synthesis of the Adda ((2S,3S,8S,9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic...
Figure 5: Structures of NRPS and PKS products in marine cyanobacteria.
Figure 6: A) Formation of the trichloroleucyl starter unit of barbamide (7) synthesis through the non-heme ir...
Figure 7: Structures of NRPS and PKS products in terrestrial cyanobacteria.
Figure 8: Synthesis of the (2S,4S)-4-methylproline moiety of nostopeptolides A (13).
Figure 9: Structures of cyanobacterial peptides that are synthesized ribosomally and post-translationally mod...
Figure 10: Formation of ester linkages and ω-amide linkage in microviridins 17 by the ATP grasp ligases MvdD a...
Figure 11: Structures of cyanobacterial sunscreen compounds.
Ratiometric fluorescent probe for enantioselective detection of D-cysteine in aqueous solution
- Xiao-bo Zhou,
- Wing-Hong Chan,
- Albert W. M. Lee and
- Chi-Chung Yeung
Beilstein J. Org. Chem. 2011, 7, 1508–1515, doi:10.3762/bjoc.7.176
- enantioselective detection of cysteine in 99:1 buffered HEPES:ACN solutions. Under the measuring conditions, the sensor demonstrates high selectivity toward Cys against Hcy and GSH, and an enantioselectivity of 3.35 can be achieved for antipodal forms of Cys. Keywords: chemosensor; D-cysteine; enantioselectivity
- ; fluorescence; ratiometric; Introduction The rapid, sensitive, and selective sensing of biologically relevant thiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) has attracted significant interest in the sensor community (Figure 1) [1]. All three of these thiols are present in living
- ratiometric fluorescent chemosensors for the detection of thiols have been constructed [29][30][31]. Recently, on the basis of a native chemical-ligation reaction, Lin and coworkers reported a FRET-based probe suitable for ratiometric imaging of cysteine in living cells [31]. Therefore, it is a challenging
Graphical Abstract
Figure 1: Structures of biological active thiols.
Figure 2: The structure of ACAQ.
Figure 3: Emission spectra of (a) Zn2+–ACAQ or (b) Cd2+–ACAQ complex (5 μM) at increasing concentrations of C...
Figure 4: Job’s plot of Cd2+–ACAQ in 10 mM HEPES buffer (pH 7.4) at 298 K. The sum of the concentrations of t...
Figure 5: Fluorescence spectra of Cd2+–ACAQ (10 µm) upon the titration of (a) D-Cys and (b) L-Cys in buffer s...
Figure 6: Fluoresence emission change of Cd2+–ACAQ at 500 nm in response to the addition of 15 equiv amino ac...
Figure 7: Fluorescence spectra of (10 µm) Cd2+–ACAQ upon the titration of various amino acids in buffer solut...
Figure 8: UV spectra of Cd2+–ACAQ (25 µm) upon the titration of (a) D-Cys, (b) L-Cys (0–12 equiv) in buffer s...
Figure 9: Partial 1H NMR spectra (400 MHz) of ACAQ (5 mM) before and after the addition of Cd2+ and then incr...
Figure 10: Proposed binding model of Cd2+–ACAQ with cysteine.
Figure 11: Reversibility study. Emission spectra of Cd2+–ACAQ complex (5 μM) with 10 equiv L-Cys in buffer sol...
A novel high-yield synthesis of aminoacyl p-nitroanilines and aminoacyl 7-amino-4-methylcoumarins: Important synthons for the synthesis of chromogenic/fluorogenic protease substrates
- Xinghua Wu,
- Yu Chen,
- Herve Aloysius and
- Longqin Hu
Beilstein J. Org. Chem. 2011, 7, 1030–1035, doi:10.3762/bjoc.7.117
- removal of the Boc protecting group and oxidation of the free amino group to the nitro group [13]. This method, however, is not applicable to methionine, tyrosine, tryptophan and cysteine, all of which are sensitive to the oxidation conditions used. As an alternative, Nα-protected amino acids were used to
- -phthalaldehyde/Nα-tert-butyloxycarbonyl-L-cysteine and HPLC analysis, and we concluded that the obtained amide product contained a small amount (1.7%) of the D-isomer resulting from the first step of carboxylate activation rather than the last two steps of selenocarboxylate generation and amidation [20]. In
Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine, histidine and tryptophan
- Axel G. Griesbeck,
- Jörg Neudörfl and
- Alan de Kiff
Beilstein J. Org. Chem. 2011, 7, 518–524, doi:10.3762/bjoc.7.60
- cysteine and S-methyl cysteine derivatives [8]. Other proteinogenic amino acids that, in principle, should also be able to show bielectrophoric behavior with aromatic side chains similar to phenylalanine are tyrosine, histidine and tryptophan. The photochemistry of the phthalimide derivatives of these
Graphical Abstract
Scheme 1: Three phthalimide/amino acid model reactions: Norrish II process of 1, PET decarboxylation of 3, PE...
Figure 1: Phthalimides from tyrosine 8, histidine 9 and tryptophan 10.
Scheme 2: PET decarboxylation/photocleavage of 8 and 9.
Figure 2: Structure of the tryptophan derivative 10 in the crystal.
Figure 3: UV–vis absorption spectra of compounds 8–10 (c = 2 × 10−4 in CH3OH).
Scheme 3: Direct, triplet-sensitized and ET-sensitized photochemistry of 10.
Figure 4: Fluorescence spectra of compounds 8–10 (c = 6 × 10−5 in CH3OH).
Scheme 4: Mechanistic scenario.
pH-Responsive chromogenic-sensing molecule based on bis(indolyl)methene for the highly selective recognition of aspartate and glutamate
- Litao Wang,
- Xiaoming He,
- Yong Guo,
- Jian Xu and
- Shijun Shao
Beilstein J. Org. Chem. 2011, 7, 218–221, doi:10.3762/bjoc.7.29
- observed upon addition of cysteine. On the other hand, no noticeable changes in color and absorption spectra were observed in the presence of various neutral amino acids and basic amino acids under the same conditions (even at much higher amino acids concentrations), which means that the receptor 1
- the protonated receptor [H2L]+. For cysteine, due to its slight acidity compared to neutral and basic amino acids, it may also partly protonate 1, however, the spectral change observed does not achieve the same level as the acidic amino acids even in the presence of 100 equiv of cysteine. On the other
Graphical Abstract
Figure 1: Structure of sensor 1.
Figure 2: Changes in UV–vis spectra of 1 (5.0 × 10−5 M) after addition of: (a) 0–0.10 mL H2O; (b) various rat...
Figure 3: pH-dependent changes in UV–vis spectra of 1 (5.0 × 10−5 M) in CH3CN/H2O (1:1, v/v) at (a) pH = 1–7,...
Figure 4: Changes in UV–vis spectra of 1 (5.0 × 10−5 M) in CH3CN/H2O (1:1, v/v) after addition of: (a) 25 equ...
The allylic chalcogen effect in olefin metathesis
- Yuya A. Lin and
- Benjamin G. Davis
Beilstein J. Org. Chem. 2010, 6, 1219–1228, doi:10.3762/bjoc.6.140
- and S-pentenyl cysteine (21b and 21c, respectively), failed to work under identical conditions in aqueous media (Scheme 7a) [17]. In order to compare the relative CM reactivity between other allylic heteroatom derivatives, further studies were carried out on the CM of allyl benzyl ether (23) and allyl
Graphical Abstract
Scheme 1: a) Variation of olefin metathesis: CM = cross-metathesis; RCM = ring-closing metathesis; ROM = ring...
Figure 1: Allylic hydroxy activation in RCM [19].
Figure 2: Possible complexes generated through preassociation of allylic alcohol with ruthenium.
Scheme 2: The influence of different OR groups on ring size-selectivity [21].
Scheme 3: Synthesis of palmerolide A precursors by Nicolaou et al. illustrates enhancement by an allylic hydr...
Scheme 4: a) Acceleration of ring-closing enyne metathesis by the allylic hydroxy group [23]. b) Proposed mode of...
Scheme 5: a) Effect of the hydroxy group on the rate and steroselectivity of ROCM [24]. b) Proposed H-bonded ruth...
Scheme 6: Plausible explanation for chemoselective CM of diene 16 [25].
Scheme 7: a) Efficient cross-metathesis of S-allylcysteine [17]. b) Comparison of relative reactivity between all...
Scheme 8: a) Macrocycle synthesis by carbonyl-relayed RCM. b) Putative complex in carbonyl-relayed RCM [33].
Scheme 9: a) Sulfur assisted cross-metathesis [17]. b) Putative unproductive chelates for larger ring sizes gener...
Scheme 10: Functionalization of Mukaiyama aldol product by CM in aqueous media [37].
Scheme 11: Comparison of reactivity between allyl sulfides and allyl selenides in aqueous cross-metathesis [38].
Scheme 12: Ring-closing metathesis on a protein [18].
Scheme 13: Expanded substrate scope of cross-metathesis on proteins [38].
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...
