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Search for "merocyanine" in Full Text gives 11 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group
- Vladimir P. Rybalkin,
- Sofiya Yu. Zmeeva,
- Lidiya L. Popova,
- Irina V. Dubonosova,
- Olga Yu. Karlutova,
- Oleg P. Demidov,
- Alexander D. Dubonosov and
- Vladimir A. Bren
Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47
- inverse photochromism), such as merocyanine forms of spiropyrans and spirooxazines, azomethine imines, thioindigoid dyes and N→O acylotropic systems [12][13][14][15]. Recently, they have been actively used to create next-generation molecular switches, materials with new properties (in particular, color
Graphical Abstract
Scheme 1: Synthesis of compound 1 and N-acylated compounds 2a–c.
Figure 1: Absorption (1), fluorescence (2, λex = 410 nm) and fluorescence excitation (3, λfl = 465 nm) spectr...
Figure 2: Electronic absorption spectra of compound 2b in acetonitrile before (1) and after 15 s (2), 35 s (3...
Scheme 2: Photoisomerization of N-acylated ketoenamines 2a–c.
Figure 3: Molecular structure of O-acylated isomer 3b. Thermal ellipsoids are drawn at the 50% probability le...
Figure 4: Fragment of the molecular packing of compound 3b, showing π–π interactions in the crystalline state...
Figure 5: Absorption spectra of compound 2a in acetonitrile before (1) and after (2) the addition of Fe2+ (c2a...
Figure 6: Changes in the absorption intensity of compound 2a in acetonitrile at 520 nm after the addition of ...
Scheme 3: Sequential interaction of compounds 2a–c with Fe2+ and AcO−.
Figure 7: Job’s plot at the wavelength 429 nm, reflecting the interaction of compound 2a with Fe2+ in acetoni...
Figure 8: Fluorescence intensity of compound 2a upon alternate addition of Fe2+ and AcO−.
Photochromic derivatives of indigo: historical overview of development, challenges and applications
- Gökhan Kaplan,
- Zeynel Seferoğlu and
- Daria V. Berdnikova
Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23
- involved in the main indigo chromophore comprising a C=C double bond substituted by two acceptors and two donor groups (Figure 4) [18]. Notably, the benzene rings make just a small contribution to the chromophore. In other words, the primary chromophore of indigo consists of two intersecting merocyanine
Graphical Abstract
Figure 1: Precursors used in the synthesis of indigo [4].
Figure 2: a) Intramolecular (a = 2.26 Å) and intermolecular (b = 2.11 Å) hydrogen bonds in indigo, b) crystal...
Figure 3: Bond length in the indigo molecule obtained from the single crystal X-ray analysis [12], the typical bo...
Figure 4: The structure of the indigo chromophore (H-chromophore, highlighted in blue), asterisk indicates th...
Figure 5: Influence of substituents in the benzene rings on the color of indigo derivatives.
Figure 6: a) E–Z photoisomerization of indigo and b) photoinduced proton transfer in the excited state, aster...
Figure 7: Structures of indigo derivatives discussed in this review.
Figure 8: Photoswitching of N,N'-diacetylindigo (9a) in CCl4 (c = 17.1 µM; cell length = 5.0 cm) irradiated w...
Figure 9: Photoisomerization of compound 18c upon irradiation with red light and schematic representation of ...
Figure 10: Schematic representation of indigo-type (left) and amide-type (right) resonances in N,N'-acetylindi...
Figure 11: Suggested intermediates for the double bond cleavage for the thermal relaxation of N,N'-diacylindig...
Figure 12: Zwitterionic resonance structures of Z-indigo.
Figure 13: Photos of crystalline N,N'-di(Boc)indigo 17a its solutions in 1) DMSO, 2) DMF, 3) N-methyl-2-pyrrol...
Figure 14: Structural isomers of indigo.
Figure 15: Photochromism of indirubin derivatives and supramolecular complexation of the E-isomers with Schrei...
Figure 16: Photoisomerization of the protonated isoindigo.
Selected peptide-based fluorescent probes for biological applications
- Debabrata Maity
Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247
- nonfluorescent and colored ring-opened merocyanine (MCH+), fluorescent and colored ring-opened merocyanine (MC) and nonfluorescent and colorless ring-closed SP forms. Tian et al. in collaboration with the Schmuck group developed a bis-SP functionalized peptide 14 for pH monitoring in lysosomes and subsequent
- after incubation with the PDA liposomes. Reprinted with permission from [59]. Copyright (2011) American Chemical Society. a) Molecular structure of peptide 14; b) the coordinate represents the states of sensor at different pH values, purple sphere: protonated merocyanine (McH+), red sphere: normal
- merocyanine (Mc), and gray sphere: spiropyran at a ring-closed state (Sp); colocalization experiments using peptide 14, LysoTracker Green DND-26 (LTG) and Hoechst 33258 in A549 cells. Cells were stained with c) 10 µM peptide 14 (channel 1: excitation: 515 nm, emission collected: 600–650 nm), d) 0.1 µM LTG
Graphical Abstract
Figure 1: Three different type of peptide-based fluorescent probes and their interaction with nucleic acids a...
Figure 2: A) Molecular structure of peptidic probe 1, Inset: HeLa cells incubated with peptide 1 (50 μM), sho...
Figure 3: A) Molecular structure of probe 2; B) fluorescence emission spectra for the titration of a 10 μM so...
Figure 4: A) Molecular structure of 3; B) fluorescence emission spectra for the titration of a 10 μM solution...
Figure 5: A) Molecular structure of 4 and 5; B) fluorescence spectra for the titration of a 0.5 μM solution o...
Figure 6: A) Molecular structure of 6; B) possible binding mode of pyrene termini of 6 to CB[8] according to ...
Figure 7: A) Molecular structure of peptidic probes 7 and 8; B) fluorescence emission spectra of probe 7 (5.0...
Figure 8: Top: Molecular structure of 9; bottom: A) fluorescence response of 9 (500 nM) upon addition of β-tr...
Figure 9: Top: Molecular structures of 10 and 11; bottom: A) fluorescence emission spectra of 10 (1.0 µM, λex...
Figure 10: A) Structure of two peptide amphiphiles 12 and 13; B) fluorescent spectra (λex = 400 nm) from a tit...
Figure 11: a) Molecular structure of peptide 14; b) the coordinate represents the states of sensor at differen...
Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates
- Phil M. Pithan,
- Sören Steup and
- Heiko Ihmels
Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82
- merocyanine formation, and the irradiation with light mainly led to photodegradation of the substrates. However, it was shown by colorimetric and fluorimetric screening assays as well as by detailed NMR spectroscopic and mass spectrometric studies that the addition of particular metal ions (Cu2+, Fe3+, and to
- photoreaction [12][15][16]. The photochromism is based on a reversible electrocyclic reaction that proceeds through the UV light-induced cleavage of the C2’–O bond of the closed, colorless form to give the colored, metastable merocyanine form, whereas the back reaction can be initiated thermally or by the
- irradiation with visible light, as is exemplarily shown for the spiroindolinonaphthoxazine 1a (Scheme 1) [15]. The merocyanine form 1aMC essentially possesses a planar structure, and because of the extended π system, the absorption maximum is significantly red-shifted in comparison to the closed form (e.g
Graphical Abstract
Scheme 1: Photo- or cation-induced ring-opening reaction of spirooxazine 1aSO; Mn+ = Pb2+, La3+, Eu3+, Tb3+ [17].
Scheme 2: Synthesis of the spirooxazine–quinolizinium conjugates 3a and 3b.
Figure 1: Colors of the solutions resulting from the addition of metal ions (c = 50 µM) to derivative 3a (c =...
Figure 2: Spectrophotometric titration of 3a (A) and 3b (B) (c = 20 µM) with Cu(BF4)2 (c = 2.44 mM) in MeCN. ...
Figure 3: Absorption (A) and fluorescence spectrum (B) of 3a in MeCN (c = 5 µM) in the absence (black) and in...
Figure 4: Emission colors of solutions resulting from the addition of metal ions (c = 50 µM) to derivative 3a...
Scheme 3: Cu2+-induced formation of the oxazole derivatives 4a and 4b.
Figure 5: 1H NMR spectra (600 MHz, 6.4–9.4 ppm) of 3a (c = 2.0 mM) in the absence (A) and in the presence (B–...
Figure 6: Spectral changes of 3a (c = 20 µM) upon the addition of Cu2+ (A) and Fe3+ (B) (cM+ = 60 µM) in MeCN...
Scheme 4: Proposed mechanism for the formation of the oxazole derivatives 4a and 4b (cf. Scheme 3); Mn+ = Cu2+, Fe3+,...
Synthesis and metal binding properties of N-alkylcarboxyspiropyrans
- Alexis Perry and
- Christina J. Kousseff
Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154
- for binding divalent metal cations and a modest increase in M2+ binding affinity correlated with increased alkycarboxylate tether length. Keywords: carboxylate ligand; merocyanine; metal binding; photochromism; spiropyran; Introduction Spiropyrans are a class of spiro-fused indolochromene (e.g
- ., C4SP, Scheme 1) which exist in photo-controlled equilibrium with their zwitterionic, fully-conjugated merocyanine isomer [1] (e.g., C4MC, Scheme 1). The controllable nature of this isomerisation and the dramatic differences in physical and chemical properties displayed by the isomeric forms, coupled
- with the facile elaboration of the spiropyran core, have made spiropyran–merocyanine systems a common motif in molecular switch and sensing applications [2]. In this respect, the difference in optical properties between colourless, non-fluorescent spiropyran and coloured, fluorescent merocyanine has
Graphical Abstract
Figure 1: General uses of N-alkylcarboxyspiropyrans.
Scheme 1: C4SP–C4MC spiropyran-merocyanine equilibrium and M2+ binding.
Scheme 2: General synthesis of N-alkylcarboxyspiropyrans.
Scheme 3: Decarboxylation of N-ethanoic acid indolium salt 3a.
Scheme 4: Lactonisation of 4-bromobutyric acid 2c.
Figure 2: N-methyl spiropyran 9.
Figure 3: Example spectra illustrating binding studies of spiropyrans with M2+. (a) 1H NMR spectrum of C10SP ...
Figure 4: ε for MC–M2+ complexes of C2SP–C12SP and 9: (left) with Zn2+; (right) with Mg2+. Values for ε were ...
Figure 5: [MC] for compounds C2SP–C12SP and 9 in the presence of various metal cations. Solutions of spiropyr...
Figure 6: [MC] for spiropyrans C2SP–C12SP, 9 and 10 (0.1 mM) in CH3CN–H2O (99.9% v/v). Samples were kept in d...
Figure 7: C6 ester derivative 10.
Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state
- Jonas Becher,
- Daria V. Berdnikova,
- Darinka Dzubiel,
- Heiko Ihmels and
- Phil M. Pithan
Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23
- ]quinolizinium was synthesized by cyclodehydration route and its optical properties in different media were investigated. The absorption and emission spectra of this compound depend on the pH of the solution. Thus, at higher pH values the deprotonation yields a merocyanine-type dye that exhibits significantly
- in a merocyanine-type conjugation (Scheme 2). A similar effect was postulated for the structurally resembling hydroxystyrylquinolizinium derivatives, such as 6 (Figure 8), that also show a red shift of the absorption upon deprotonation, although to a larger extent (from 405 to 472 nm) [50][51][52
Graphical Abstract
Figure 1: Structures of quinolizinium derivatives 1a–c and 2.
Scheme 1: Synthesis of 3-hydroxynaphtho[1,2-b]quinolizinium bromide (2).
Figure 2: Absorption (A, c = 100 µM) and normalized emission spectra (B, c = 10 µM or Abs. = 0.1 at λex) of d...
Figure 3: Photometric (A) and fluorimetric (B) acid–base titration (λex = 380 nm) of naphthoquinolizinium 2 (c...
Figure 4: Absorption spectra of 2 (c = 100 µM) in MeOH (A) and MeCN (B). Black lines: without additive, red: ...
Figure 5: Normalized emission spectra of 2 (c = 10 µM) in MeOH (A, λex = 400 nm) and MeCN (B, λex = 398 nm). ...
Figure 6: Photometric titration of CB[7] (c = 0.45 mM) to 2 (c = 15 µM) in BPE buffer (with 10% v/v DMSO) at ...
Figure 7: Photometric (A) and fluorimetric (B) acid–base titration (λex = 380 nm) of 2 (c = 15 µM) in the pre...
Scheme 2: Acid–base equilibrium of hydroxynaphthoquinolizinium 2.
Figure 8: Structures of quinolizinium derivatives 6–8.
One-pot three-component synthesis and photophysical characteristics of novel triene merocyanines
- Christian Muschelknautz,
- Robin Visse,
- Jan Nordmann and
- Thomas J. J. Müller
Beilstein J. Org. Chem. 2014, 10, 599–612, doi:10.3762/bjoc.10.51
- are slightly red-shifted and appear between 519 and 532 nm as a result of a J-aggregation [45]. Apparently, the aryl substitution on the triene moiety only affects the absorption bands to a minor extent. The merocyanine character of the 1-styryleth-2-enylideneindolones 8 is additionally supported by
- -aggregation the absorption bands of the films are red-shifted and appear between 599 and 623 nm (Table 4, Figure 6). The benzothiazol-terminated merocyanine 10h displays in dichloromethane solution a hypsochromically shifted absorption band at 563 nm with the highest molar extinction coefficient (Table 4
- , entry 13), yet for the amorphous film the most pronounced bathochromic shift in the series of the merocyanines 10 (Figure 7). In the solid state a merocyanine characteristic metallic green luster can be seen. Again, the aryl substitution on the triene moiety only affects the absorption bands to a minor
Graphical Abstract
Figure 1: Linear push–pull solid-state diene lumophores with conformationally flexible and fixed acceptor moi...
Scheme 1: Three-component synthesis of 1-styryleth-2-enylideneindolones 8.
Figure 2: DFT-computed energy differences of the stereoisomers of 2Z,4Z-8a and 2Z,4E-8a.
Scheme 2: Three-component synthesis of 4-(1,3,3-trimethylindolin-2-ylidene)but-2-en-1-ylideneindolones 10.
Figure 3: DFT-computed energy differences of the stereoisomers of 10a and 10h.
Scheme 3: Mechanistic rationale of the three-component sequence furnishing the 1-styryleth-2-enylideneindolon...
Figure 4: DFT-computed (B3LYP functional, 6-31G* basis set) HOMO (left) and LUMO (right) of merocyanine 8a.
Figure 5: Absorption and emission spectrum of the dropcasted film of compound 8a (recorded at room temperatur...
Figure 6: Absorption spectrum of the dropcasted film of compound 10d (recorded at room temperature, normalize...
Figure 7: Absorption spectra of compound 10h in dichloromethane (right trace) and of the dropcasted film (lef...
Figure 8: DFT-computed (B3LYP functional, 6-311G(d,p) basis set) FMOs (HOMO, bottom; LUMO (center), and LUMO+...
Diarylethene-modified nucleotides for switching optical properties in DNA
- Sebastian Barrois and
- Hans-Achim Wagenknecht
Beilstein J. Org. Chem. 2012, 8, 905–914, doi:10.3762/bjoc.8.103
- only is a structural change observed but a large change in polarity is yielded additionally [10][22]. It is expected that the ring-closed spiropyran form of this molecular switch does not insert into the base stack due to its twisted structure, but the open merocyanine form could intercalate based on
- its planarity and polarity. This assumption was experimentally verified by synthetic spiropyrans as noncovalent DNA and RNA binders [23][24][25]. As expected, ground-state interactions between the noncovalently bound molecular switch and the DNA bases were detected in the case of the merocyanine form
Graphical Abstract
Scheme 1: Spiropyran as DNA base surrogate 1, DNA base modifications 2 and 3, and diarylethene-modified nucle...
Scheme 2: Synthesis of diarylethene-modified 2’-deoxyuridines 4 [30], 5 and 6.
Figure 1: Photoswitching properties of nucleosides 4–6 (each 20 mM in MeCN, rt). Top: Irradiation of 4 at 242...
Scheme 3: Synthesis of DNA building block 17 [30] and sequences of diarylethene-modified DNA1–DNA4.
Figure 2: Irradiation of dsDNA2 at 310 nm (A, left) and plot of kinetic trace of absorption changes at 450 nm...
Figure 3: UV–vis absorption spectra of ssDNA1–ssDNA4 (2.5 μM in 50 mM Na–Pi buffer, pH 7, 250 mM NaCl, rt).
A perfluorocyclopentene based diarylethene bearing two terpyridine moieties – synthesis, photochemical properties and influence of transition metal ions
- Falk Wehmeier and
- Jochen Mattay
Beilstein J. Org. Chem. 2010, 6, No. 53, doi:10.3762/bjoc.6.53
- processes between the ruthenium nuclei. On the other hand the closed isomer 10aC might act as an acceptor; a similar effect has been observed with a spiropyran moiety bridging two terpyridine units, whose (closed) merocyanine form inhibits the energy transfer between metal centres and thus acts as a T
Graphical Abstract
Scheme 1: Synthesis of twofold iodinated bis(benzo[b]thiophenyl)perfluorocyclopentene 4.
Scheme 2: Synthesis of terpyridinyl boronic acids 9a and 9b.
Scheme 3: Synthesis of the bis(terpyridinyl)diarylethenes 10a and 10b.
Scheme 4: Photochromic reaction of the free ligand 10a.
Figure 1: UV–vis-spectra of 10a before (solid), after UV-irradiation (dashed) and after irradiation with vis ...
Scheme 5: Synthesis of the binuclear Ru(II)-complex 12.
Figure 2: UV–vis-spectra of 12 before (solid), after UV-irradiation (dashed) and after irradiation with vis l...
Figure 3: UV–vis-spectra of 12 before (dashed), after UV-irradiation (dotted), the difference (solid) and fre...
Figure 4: UV–vis-spectra of [Fe2+@10a] before (solid), after UV-irradiation (dashed) and after irradiation wi...
Figure 5: UV–vis-spectra of [Zn2+@10a] before (solid), after UV-irradiation (dashed) and after irradiation wi...
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...
Synthesis of novel photochromic pyrans via palladium- mediated reactions
- Christoph Böttcher,
- Gehad Zeyat,
- Saleh A. Ahmed,
- Elisabeth Irran,
- Thorben Cordes,
- Cord Elsner,
- Wolfgang Zinth and
- Karola Rueck-Braun
Beilstein J. Org. Chem. 2009, 5, No. 25, doi:10.3762/bjoc.5.25
- (closed forms), also referred to as chromenes, leads to the formation of interconverting photoisomers of the open merocyanine-type (quinoidal, zwitterionic and hybrid forms and their stereoisomers), depending upon the substitution pattern of the parent pyrans and the conditions employed (Scheme 1
- ). Typically the thermal reversion of the open forms is very fast [17][18][19][20]. Quite recently, the formation of allene intermediates at low temperatures was also reported in the literature. They originate from open merocyanine isomers and are formed via a 1,5-hydrogen shift reaction [21][22]. However
- generates a flexible C3–C4 single bond within the open merocyanine forms in place of the former double bond of the pyran ring (Scheme 1), resulting in a significant structural alteration of the β-turn scaffold. Herein we describe the synthesis of functionalized photochromic pyrans by palladium-catalyzed
Graphical Abstract
Scheme 1: Photochromism of 2H-chromenes.
Scheme 2: Synthesis of functionalized pyrans from 2-bromo-3H-naphtho[2,1-b]pyrans and 3-bromo-2H-1-benzopyran...
Scheme 3: Synthesis of the 2-bromo-3H-naphtho[2,1-b]pyran 1 and the 3-bromo-2H-1-benzopyrans 2a/b.
Scheme 4: Ring contraction observed during the cyanation approach towards the synthesis of 3.
Scheme 5: Palladium-catalyzed Sonogashira-coupling of 2-bromo-3H-naphtho[2,1-b]pyran 1.
Scheme 6: Palladium-catalyzed cyanation and carbonylation of 3-bromo-2H-1-benzopyrans 2a/b.
Figure 1: Data from time-resolved measurements of compound 5a. a) and b): Results from fs-pump-probe-spectros...
