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Search for "electronic spectra" in Full Text gives 19 result(s) in Beilstein Journal of Organic Chemistry.
Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186
- more intensity) were observed. On the other hand, a strong band with absorption maxima at 337.89 nm along with three more bands at 313.78 nm, 301.47 nm, and 283.77 nm were noticed in tri-DPM based truxene 18. Noticeably, all three DPMs (14, 16, and 18) gave almost similar electronic spectra (Figure 2
Graphical Abstract
Figure 1: Structures of some reported mono-, di- and tri-dipyrromethane derivatives [44-49].
Scheme 1: Synthesis of the mono-DPM-based truxene derivative 14.
Scheme 2: Synthesis of di- and tri-DPM-based truxene derivatives 16 and 18.
Figure 2: UV–vis absorption (left) and fluorescence spectra (right) recorded in chloroform.
Figure 3: Time-resolved fluorescence lifetime.
Synthesis and characterization of water-soluble C60–peptide conjugates
- Yue Ma,
- Lorenzo Persi and
- Yoko Yamakoshi
Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71
- ® water (pH 7.0) and in TRIS buffer (pH 9.0), respectively (Figure 4). The spectrum of C60–oligo-Lys (5a) was in good agreement with that typically observed for C60 monoadduct derivatives [47]. The electronic spectra of the fulleropyrrolidines were characterized by notable π–π* absorption in the UV region
Graphical Abstract
Figure 1: a) Synthesis of C60–oligopeptide conjugates 5a–c and b) synthesis of compound 3. Fulleropyrrolidine...
Figure 2: Structure of C60–oligo-Lys (5a), C60–oligo-Glu (5b), and C60–oligo-Arg (5c) and images of dissolved...
Figure 3: DLS diagrams of C60–peptide conjugates 5a (1 mM, in Milli-Q® water), 5b (1 mM, in Milli-Q® water or...
Figure 4: UV–vis spectra of C60–peptide conjugates 5a and 5b (20 μM in Milli-Q® water for 5a and in pH 9.0 TR...
Figure 5: 1H NMR spectrum of C60–peptide conjugate 5a in D2O (above) and of the precursor monoadduct in CDCl3...
Figure 6: 13C NMR spectrum of C60–peptide conjugate 5a in D2O and of the precursor monoadduct in CDCl3 at 150...
Figure 7: a) X-band ESR spectra of the 4-oxo-TEMP adduct with 1O2 generated by C60–oligo-Lys (5a) and rose be...
Synthesis and characterization of S,N-heterotetracenes
- Astrid Vogt,
- Florian Henne,
- Christoph Wetzel,
- Elena Mena-Osteritz and
- Peter Bäuerle
Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214
- [22][27], organic field-effect transistors [28], or sensors [23]. The interesting structure–property relationships of the S,N-heteroacene series inspired as well theoretical work. In this respect, De Simone et al. computed electronic spectra of the neutral, charged radical cationic, and dicationic
Graphical Abstract
Figure 1: Heteroacenes: tetrathienoacene (TTA), S,N-heteroacenes SN4, SN4', and SN4''.
Scheme 1: Synthesis of fused S,N-heterotetracene SN4 9 starting from thieno[3,2-b]thiophene (1).
Scheme 2: Synthesis of parent H-SN4 13 via the azide route.
Scheme 3: Synthesis of tetracyclic H-SN4 13 via the Cadogan route.
Scheme 4: Synthesis of tetracyclic indole derivative 19 via the Cadogan route.
Scheme 5: Synthesis of hexacyclic heteroacene SN4' 22 via the Cadogan route.
Scheme 6: Synthesis of heterotetracene SN4'' 33 via the azide and Buchwald–Hartwig amination route.
Figure 2: UV–vis absorption spectra of TTA, Hex-SN4 9, Pr-SN4'' 33 and fluorescence spectrum of 33 in THF at ...
Figure 3: Energy diagram of the frontier molecular orbitals of heterotetracenes TTA, 9, 13, 19, 22, and 33, a...
Models of necessity
- Timothy Clark and
- Martin G. Hicks
Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137
- results in terms of the Lewis picture is to provide hard, physically observable properties of molecules [34] such as structures, energies (and energy differences), molecular electrostatic potential in space [35], polarizability [36] electronic spectra [37] or reactivity. Some of these properties may then
Graphical Abstract
Figure 1: Representation of clozapine to emphasize the quantum mechanical characteristics of the molecule. Th...
Figure 2: Jacobus van’t Hoff’s molecular models. The photography was reproduced from: https://rijksmuseumboer...
Figure 3: IUPAC name, canonical SMILES, InChI and InChI key, Lewis structure (2D line diagram) and 3D ball-an...
Figure 4: Conceptual distinction between polarization and charge transfer. The distinction depends entirely o...
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
- the rigid coordination of the imidazole group to the metal ion, which prevents the rotation of the group needed for cyclization. Families of diarylethene-bases ligands with spatial proximity of coordination site (blue) and photoactive framework (red). Electronic spectra of diarylethene 6 upon UV
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...
Extending mechanochemical porphyrin synthesis to bulkier aromatics: tetramesitylporphyrin
- Qiwen Su and
- Tamara D. Hamilton
Beilstein J. Org. Chem. 2019, 15, 1149–1153, doi:10.3762/bjoc.15.111
- and purified by distillation once per week after discoloration appeared. The electronic spectra were recorded on a Perkin Elmer Lambda 850 UV–vis spectrophotometer, measured from 200–800 nm at 1 nm intervals. The samples were placed in quartz cuvettes with a 1 cm path length. 1H NMR spectra were
Graphical Abstract
Figure 1: A) Porphyrin structure and labelling system. B) Substituents in the ortho-position of the group att...
Scheme 1: Steps leading to the formation of a porphyrin.
Scheme 2: Mechanochemical synthesis of tetramesitylporphyrin.
One hundred years of benzotropone chemistry
- Arif Dastan,
- Haydar Kilic and
- Nurullah Saracoglu
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
Graphical Abstract
Scheme 1: Tropone (1), tropolone (2) and their resonance structures.
Figure 1: Natural products containing a tropone nucleus.
Figure 2: Possible isomers 11–13 of benzotropone.
Scheme 2: Synthesis of benzotropones 11 and 12.
Scheme 3: Oxidation products of benzotropylium fluoroborate (16).
Scheme 4: Oxidation of 7-bromo-5H-benzo[7]annulene (22).
Scheme 5: Synthesis of 4,5-benzotropone (11) using o-phthalaldehyde (27).
Scheme 6: Synthesis of 4,5-benzotropone (11) starting from oxobenzonorbornadiene 31.
Scheme 7: Acid-catalyzed cleavage of oxo-bridge of 34.
Scheme 8: Synthesis of 4,5-benzotropone (11) from o-xylylene dibromide (38).
Scheme 9: Synthesis of 4,5-benzotropone (11) via the carbene adduct 41.
Scheme 10: Heck coupling strategy for the synthesis of 11.
Scheme 11: Synthesis of benzofulvalenes via carbonyl group of 4,5-benzotropone (11).
Figure 3: Some cycloheptatrienylium cations.
Scheme 12: Synthesis of condensation product 63 and its subsequent oxidative cyclization products.
Figure 4: A novel series of benzo[7]annulenes prepared from 4,5-benzotropone (11).
Scheme 13: Preparation of substituted benzo[7]annulene 72 using the Mukaiyama-Michael reaction.
Figure 5: Possible benzo[7]annulenylidenes 73–75.
Scheme 14: Thermal and photochemical decomposition of 7-diazo-7H-benzo[7]annulene (76) and the trapping of int...
Scheme 15: Synthesis of benzoheptafulvalene 86.
Scheme 16: Synthesis of 7-(diphenylmethylene)-7H-benzo[7]annulene (89).
Scheme 17: Reaction of 4,5-benzotropone (11) with dimethyl diazomethane.
Scheme 18: Synthesis of dihydrobenzomethoxyazocine 103.
Scheme 19: Synthesis and reducibility of benzo-homo-2-methoxyazocines.
Scheme 20: Synthesis of 4,5-benzohomotropones 104 and 115 from 4,5-benzotropones 11 and 113.
Scheme 21: A catalytic deuterogenation of 4,5-benzotropone (11) and synthesis of 5-monosubstituted benzo[7]ann...
Scheme 22: Synthesis of methyl benzo[7]annulenes 131 and 132.
Scheme 23: Ambident reactivity of halobenzo[7]annulenylium cations 133a/b.
Scheme 24: Preparation of benzo[7]annulenylidene–iron complexes 147.
Scheme 25: Synthesis of 1-ethynylbenzotropone (150) and the etheric compound 152 from 4,5-benzotropone (11) wi...
Scheme 26: Thermal decomposition of 4,5-benzotropone (11).
Scheme 27: Reaction of 4,5-benzotropone (11) with 1,2-ethanediol and 1,2-ethanedithiol.
Scheme 28: Conversions of 1-benzosuberone (162) to 2,3-benzotropone (12).
Scheme 29: Synthesis strategies for 2,3-bezotropone (12) using 1-benzosuberones.
Scheme 30: Oxidation-based synthesis of 2,3-benzotropone (12) via 1-benzosuberone (162).
Scheme 31: Synthesis of 2,3-benzotropone (12) from α-tetralone (171) via ring-expansion.
Scheme 32: Preparation of 2,3-benzotropone (12) by using of benzotropolone 174.
Figure 6: Benzoheptafulvenes as condensation products of 2,3-benzotropone (12).
Scheme 33: Conversion of 2,3-benzotropone (12) to tosylhydrazone salt 182 and gem-dichloride 187.
Figure 7: Benzohomoazocines 191–193 and benzoazocines 194–197.
Scheme 34: From 2,3-benzotropone (12) to carbonium ions 198–201.
Scheme 35: Cycloaddition reactions of 2,3-benzotropone (12).
Scheme 36: Reaction of 2,3-benzotropone (12) with various reagents and compounds.
Figure 8: 3,4-Benzotropone (13) and its resonance structure.
Scheme 37: Synthesis of 6,7-benzobicyclo[3.2.0]hepta-3,6-dien-2-one (230).
Figure 9: Photolysis and thermolysis products of 230.
Figure 10: Benzotropolones and their tautomeric structures.
Scheme 38: Synthesis strategies of 4,5-benzotropolone (238).
Scheme 39: Synthesis protocol for 2-hydroxy-4,5-benzotropone (238) using oxazole-benzo[7]annulene 247.
Figure 11: Some quinoxaline and pyrazine derivatives 254–256 prepared from 4,5-benzotropolone (238).
Scheme 40: Nitration product of 4,5-benzotropolone (238) and its isomerization to 1-nitro-naphthoic acid (259)....
Scheme 41: Synthesis protocol for 6-hydroxy-2,3-benzotropone (239) from benzosuberone (162).
Scheme 42: Various reactions via 6-hydroxy-2,3-benzotropone (239).
Scheme 43: Photoreaction of 6-hydroxy-2,3-benzotropone (239).
Scheme 44: Synthesis of 7-hydroxy-2,3-benzotropone (241) from benzosuberone (162).
Scheme 45: Synthesis strategy for 7-hydroxy-2,3-benzotropone (241) from ketone 276.
Scheme 46: Synthesis of 7-hydroxy-2,3-benzotropone (241) from β-naphthoquinone (280).
Scheme 47: Synthesis of 7-hydroxy-2,3-benzotropone (241) from bicyclic endoperoxide 213.
Scheme 48: Synthesis of 7-hydroxy-2,3-benzotropone (241) by ring-closing metathesis.
Figure 12: Various monosubstitution products 289–291 of 7-hydroxy-2,3-benzotropone (241).
Scheme 49: Reaction of 7-hydroxy-2,3-benzotropone (241) with various reagents.
Scheme 50: Synthesis of 4-hydroxy-2,3-benzotropones 174 and 304 from diketones 300/301.
Scheme 51: Catalytic hydrogenation of diketones 300 and 174.
Scheme 52: Synthesis of halo-benzotropones from alkoxy-naphthalenes 306, 307 and 310.
Figure 13: Unexpected byproducts 313–315 during synthesis of chlorobenzotropone 309.
Figure 14: Some halobenzotropones and their cycloadducts.
Scheme 53: Multisep synthesis of 2-chlorobenzotropone 309.
Scheme 54: A multistep synthesis of 2-bromo-benzotropone 26.
Scheme 55: A multistep synthesis of bromo-2,3-benzotropones 311 and 316.
Scheme 56: Oxidation reactions of 8-bromo-5H-benzo[7]annulene (329) with some oxidants.
Scheme 57: Synthesis of 2-bromo-4,5-benzotropone (26).
Scheme 58: Synthesis of 6-chloro-2,3-benzotropone (335) using LiCl and proposed intermediate 336.
Scheme 59: Reaction of 7-bromo-2,3-benzotropone (316) with methylamine.
Scheme 60: Reactions of bromo-2,3-benzotropones 26 and 311 with dimethylamine.
Scheme 61: Reactions of bromobenzotropones 311 and 26 with NaOMe.
Scheme 62: Reactions of bromobenzotropones 26 and 312 with t-BuOK in the presence of DPIBF.
Scheme 63: Cobalt-catalyzed reductive cross-couplings of 7-bromo-2,3-benzotropone (316) with cyclic α-bromo en...
Figure 15: Cycloadduct 357 and its di-π-methane rearrangement product 358.
Scheme 64: Catalytic hydrogenation of 2-chloro-4,5-benzotropone (311).
Scheme 65: Synthesis of dibromo-benzotropones from benzotropones.
Scheme 66: Bromination/dehydrobromination of benzosuberone (162).
Scheme 67: Some transformations of isomeric dibromo-benzotropones 261A/B.
Scheme 68: Transformations of benzotropolone 239B to halobenzotropolones 369–371.
Figure 16: Bromobenzotropolones 372–376 and 290 prepared via bromination/dehydrobromination strategy.
Scheme 69: Synthesis of some halobenzotropolones 289, 377 and 378.
Figure 17: Bromo-chloro-derivatives 379–381 prepared via chlorination.
Scheme 70: Synthesis of 7-iodo-3,4-benzotropolone (382).
Scheme 71: Hydrogenation of bromobenzotropolones 369 and 370.
Scheme 72: Debromination reactions of mono- and dibromides 290 and 375.
Figure 18: Nitratation and oxidation products of some halobenzotropolenes.
Scheme 73: Azo-coupling reactions of some halobenzotropolones 294, 375 and 378.
Figure 19: Four possible isomers of dibenzotropones 396–399.
Figure 20: Resonance structures of tribenzotropone (400).
Scheme 74: Two synthetic pathways for tribenzotropone (400).
Scheme 75: Synthesis of tribenzotropone (400) from dibenzotropone 399.
Scheme 76: Synthesis of tribenzotropone (400) from 9,10-phenanthraquinone (406).
Scheme 77: Synthesis of tribenzotropone (400) from trifluoromethyl-substituted arene 411.
Figure 21: Dibenzosuberone (414).
Figure 22: Reduction products 415 and 416 of tribenzotropone (400).
Figure 23: Structures of tribenzotropone dimethyl ketal 417 and 4-phenylfluorenone (412) and proposed intermed...
Figure 24: Structures of benzylidene- and methylene-9H-tribenzo[a,c,e][7]annulenes 419 and 420 and chiral phos...
Figure 25: Structures of tetracyclic alcohol 422, p-quinone methide 423 and cation 424.
Figure 26: Structures of host molecules 425–427.
Scheme 78: Synthesis of non-helical overcrowded derivatives syn/anti-431.
Figure 27: Hexabenzooctalene 432.
Figure 28: Structures of possible eight isomers 433–440 of naphthotropone.
Scheme 79: Synthesis of naphthotropone 437 starting from 1-phenylcycloheptene (441).
Scheme 80: Synthesis of 10-hydroxy-11H-cyclohepta[a]naphthalen-11-one (448) from diester 445.
Scheme 81: Synthesis of naphthotropone 433.
Scheme 82: Synthesis of naphthotropones 433 and 434 via cycloaddition reaction.
Scheme 83: Synthesis of naphthotropone 434 starting from 452.
Figure 29: Structures of tricarbonyl(tropone)irons 458, and possible cycloadducts 459.
Scheme 84: Synthesis of naphthotropone 436.
Scheme 85: Synthesis of precursor 465 for naphthotropone 435.
Scheme 86: Generation of naphthotropone 435 from 465.
Figure 30: Structures of tropylium cations 469 and 470.
Figure 31: Structures of tropylium ions 471+.BF4−, 472+.BF4−, and 473+.BF4−.
Scheme 87: Synthesis of tropylium ions 471+.BF4− and 479+.ClO4−.
Scheme 88: Synthesis of 1- and 2-methylanthracene (481 and 482) via carbene–carbene rearrangement.
Figure 32: Trapping products 488–490.
Scheme 89: Generation and chemistry of a naphthoannelated cycloheptatrienylidene-cycloheptatetraene intermedia...
Scheme 90: Proposed intermediates and reaction pathways for adduct 498.
Scheme 91: Exited-state intramolecular proton transfer of 505.
Figure 33: Benzoditropones 506 and 507.
Scheme 92: Synthesis of benzoditropone 506e.
Scheme 93: Synthetic approaches for dibenzotropone 507 via tropone (1).
Scheme 94: Formation mechanisms of benzoditropone 507 and 516 via 515.
Scheme 95: Synthesis of benzoditropones 525 and 526 from pyromellitic dianhydride (527).
Figure 34: Possible three benzocyclobutatropones 534–536.
Scheme 96: Synthesis of benzocyclobutatropones 534 and 539.
Scheme 97: Synthesis attempts for benzocyclobutatropone 545.
Scheme 98: Generation and trapping of symmetric benzocyclobutatropone 536.
Scheme 99: Synthesis of chloro-benzocyclobutatropone 552 and proposed mechanism of fluorenone derivatives.
Scheme 100: Synthesis of tropolone analogue 559.
Scheme 101: Synthesis of tropolones 561 and 562.
Figure 35: o/p-Tropoquinone rings (563 and 564) and benzotropoquinones (565–567).
Scheme 102: Synthesis of benzotropoquinone 566.
Scheme 103: Synthesis of benzotropoquinone 567 via a Diels–Alder reaction.
Figure 36: Products 575–577 through 1,2,3-benzotropoquinone hydrate 569.
Scheme 104: Structures 578–582 prepared from tropoquinone 567.
Figure 37: Two possible structures 583 and 584 for dibenzotropoquinone, and precursor compound 585 for 583.
Scheme 105: Synthesis of saddle-shaped ketone 592 using dibenzotropoquinone 584.
Polysubstituted ferrocenes as tunable redox mediators
- Sven D. Waniek,
- Jan Klett,
- Christoph Förster and
- Katja Heinze
Beilstein J. Org. Chem. 2018, 14, 1004–1015, doi:10.3762/bjoc.14.86
- ). The poor agreement of TD-DFT calculated electronic spectra of metallocenes and derivatives with experimental data has been noted before. Improvements have been achieved by testing different functionals [84][85] and by including vibrational distortions of the ferrocene geometry into the calculations
Graphical Abstract
Scheme 1: Selected transformations with ferrocene/ferrocenium as SET reagents (a) [27], catalyzed (b,c) [29-31] and medi...
Scheme 2: Methyl esters of ferrocene carboxylic acids 1 [45,46], 2 [47-49], 2a [50], 2b [51,52], 3, 4 [54] and pseudo octahedral high-spin...
Figure 1: Normalized cyclic voltammograms for anodic sweeps of 1–4 in CH2Cl2/[n-Bu4N][B(C6F5)4] (scan rate 10...
Figure 2: Electrochemical potentials E1/2 (vs FcH/FcH+) of esters 1–4 versus sum of Hammett values ∑σp/m with...
Figure 3: a) Partial ATR IR spectra (transmission normalized, C=O stretching vibration region) of solids 1–4....
Figure 4: IR spectroelectrochemical oxidation of 3 to 3+ in CH2Cl2/[n-Bu4N][B(C6F5)4] (C=O stretching vibrati...
Figure 5: a) Normalized UV–vis spectra of 1–4 in CH2Cl2. b) Normalized UV–vis absorptions of 1+–4+ in CH2Cl2/[...
Figure 6: Absorption energy E of ferrocene bands of 1–4 (a) and energies of the low energy absorption maxima ...
Figure 7: UV–vis spectroelectrochemical oxidation of 3 in CH2Cl2/[n-Bu4N][B(C6F5)4] (0–1.1 V vs Ag pseudo ref...
Figure 8: 1H NMR oxidation titration of 3 in CD2Cl2 with [N(2,4-C6H3Br2)3]+ as oxidant. a[N(2,4-C6H3Br2)3]. b...
5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines
- Ranjana Aggarwal and
- Suresh Kumar
Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15
- techniques like electronic spectra, viscosity measurement and thermal denaturation. Ahmetaj et al. [105] described a simple and efficient protocol for the synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine-3-carboxamides 166 from the reaction of 5-aminopyrazole 161 with (E)-3-(dimethylamino)-1-(heteroaryl
Graphical Abstract
Figure 1: Selected examples of drugs with fused pyrazole rings.
Figure 2: Typical structures of some fused pyrazoloazines from 5-aminopyrazoles.
Scheme 1: Regiospecific synthesis of 4 and 6-trifluoromethyl-1H-pyrazolo[3,4-b]pyridines.
Scheme 2: Synthesis of pyrazolo[3,4-b]pyridine-6-carboxylates.
Scheme 3: Synthesis of 1,4,6-triaryl-1H-pyrazolo[3,4-b]pyridines with ionic liquid .
Scheme 4: Synthesis of coumarin-based isomeric tetracyclic pyrazolo[3,4-b]pyridines.
Scheme 5: Synthesis of 6-substituted pyrazolo[3,4-b]pyridines under Heck conditions.
Scheme 6: Microwave-assisted palladium-catalyzed synthesis of pyrazolo[3,4-b]pyridines.
Scheme 7: Acid-catalyzed synthesis of pyrazolo[3,4-b]pyridines via enaminones.
Scheme 8: Synthesis of pyrazolo[3,4-b]pyridines via aza-Diels–Alder reaction.
Scheme 9: Synthesis of macrocyclane fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 10: Three-component synthesis of 4,7-dihydro-1H-pyrazolo[3,4-b]pyridine derivatives.
Scheme 11: Ultrasonicated synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-2,6'(1'H)-diones.
Scheme 12: Synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine] derivatives under conventional heating co...
Scheme 13: Nanoparticle-catalyzed synthesis of pyrazolo[3,4-b]pyridine-spiroindolinones.
Scheme 14: Microwave-assisted multicomponent synthesis of spiropyrazolo[3,4-b]pyridines.
Scheme 15: Unexpected synthesis of naphthoic acid-substituted pyrazolo[3,4-b]pyridines.
Scheme 16: Multicomponent synthesis of variously substituted pyrazolo[3,4-b]pyridine derivatives.
Scheme 17: Three-component synthesis of 4,7-dihydropyrazolo[3,4-b]pyridines and pyrazolo[3,4-b]pyridines.
Scheme 18: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanediones.
Scheme 19: Ultrasound-mediated three-component synthesis of pyrazolo[3,4-b]pyridines.
Scheme 20: Multicomponent synthesis of 4-aryl-3-methyl-1-phenyl-4,6,8,9-tetrahydropyrazolo [3,4-b]thiopyrano[4...
Scheme 21: Synthesis of 2,3-dihydrochromeno[4,3-d]pyrazolo[3,4-b]pyridine-1,6-diones.
Scheme 22: FeCl3-catalyzed synthesis of o-hydroxyphenylpyrazolo[3,4-b]pyridine derivatives.
Scheme 23: Ionic liquid-mediated synthesis of pyrazolo[3,4-b]pyridines.
Scheme 24: Microwave-assisted synthesis of pyrazolo[3,4-b]pyridines.
Scheme 25: Multicomponent synthesis of pyrazolo[3,4-b]pyridine-5-carbonitriles.
Scheme 26: Unusual domino synthesis of 4,7-dihydropyrazolo[3,4-b]pyridine-5-nitriles.
Scheme 27: Synthesis of 4,5,6,7-tetrahydro-4H-pyrazolo[3,4-b]pyridines under conventional heating and ultrasou...
Scheme 28: L-Proline-catalyzed synthesis of of pyrazolo[3,4-b]pyridine.
Scheme 29: Microwave-assisted synthesis of 5-aminoarylpyrazolo[3,4-b]pyridines.
Scheme 30: Microwave-assisted multi-component synthesis of pyrazolo[3,4-e]indolizines.
Scheme 31: Synthesis of fluoropropynyl and fluoroalkyl substituted pyrazolo[1,5-a]pyrimidine.
Scheme 32: Acid-catalyzed synthesis of pyrazolo[1,5-a]pyrimidine derivatives.
Scheme 33: Chemoselective and regiospecific synthesis of 2-(3-methylpyrazol-1’-yl)-5-methylpyrazolo[1,5-a]pyri...
Scheme 34: Regioselective synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 35: Microwave-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidine carboxylates.
Scheme 36: Microwave and ultrasound-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 37: Base-catalyzed unprecedented synthesis of pyrazolo[1,5-a]pyrimidines via C–C bond cleavage.
Scheme 38: Synthesis of aminobenzothiazole/piperazine linked pyrazolo[1,5-a]pyrimidines.
Scheme 39: Synthesis of aminoalkylpyrazolo[1,5-a]pyrimidine-7-amines.
Scheme 40: Synthesis of pyrazolo[1,5-a]pyrimidines from condensation of 5-aminopyrazole 126 and ethyl acetoace...
Scheme 41: Synthesis of 7-aminopyrazolo[1,5-a]pyrimidines.
Scheme 42: Unexpected synthesis of 7-aminopyrazolo[1,5-a]pyrimidines under solvent free and solvent-mediated c...
Scheme 43: Synthesis of N-(4-aminophenyl)-7-aryloxypyrazolo[1,5-a]pyrimidin-5-amines.
Scheme 44: Base-catalyzed synthesis of 5,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 45: Synthesis of 6,7-dihydropyrazolo[1,5-a]pyrimidines in PEG-400.
Scheme 46: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine-3-carboxamides.
Scheme 47: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine derivatives under conventional heating and micro...
Scheme 48: Synthesis of N-aroylpyrazolo[1,5-a]pyrimidine-5-amines.
Scheme 49: Regioselective synthesis of ethyl pyrazolo[1,5-a]pyrimidine-7-carboxylate.
Scheme 50: Sodium methoxide-catalyzed synthesis of 3-cyano-6,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 51: Synthesis of various pyrazolo[3,4-d]pyrimidine derivatives.
Scheme 52: Synthesis of hydrazinopyrazolo[3,4-d]pyrimidine derivatives.
Scheme 53: Synthesis of N-arylidinepyrazolo[3,4-d]pyrimidin-5-amines.
Scheme 54: Synthesis of pyrazolo[3,4-d]pyrimidinyl-4-amines.
Scheme 55: Iodine-catalyzed synthesis of pyrazolo[3,4-d]pyrimidinones.
Scheme 56: Synthesis of ethyl 6-amino-2H-pyrazolo[3,4-d]pyrimidine-4-carboxylate.
Scheme 57: Synthesis of 4-substituted-(3,6-dihydropyran-4-yl)-1H-pyrazolo[3,4-d]pyrimidines.
Scheme 58: Synthesis of 1-(2,4-dichlorophenyl)pyrazolo[3,4-d]pyrimidin-4-yl carboxamides.
Scheme 59: Synthesis of 5-(1,3,4-thidiazol-2-yl)pyrazolo[3,4-d]pyrimidine.
Scheme 60: One pot POCl3-catalyzed synthesis of 1-arylpyrazolo[3,4-d]pyrimidin-4-ones.
Scheme 61: Synthesis of 4-amino-N1,C3-dialkylpyrazolo[3,4-d]pyrimidines under Suzuki conditions.
Scheme 62: Microwave-assisted synthesis of pyrazolo[3,4-b]pyrazines.
Scheme 63: Synthesis and derivatization of pyrazolo[3,4-b]pyrazine-5-carbonitriles.
Scheme 64: Synthesis of 2-thioxo-pyrazolo[1,5-a][1,3,5]triazin-4-ones.
Scheme 65: Synthesis of 2,3-dihydropyrazolo[1,5-a][1,3,5]triazin-4(1H)-one.
Scheme 66: Synthesis of pyrazolo[1,5-a][1,3,5]triazine-8-carboxylic acid ethyl ester.
Scheme 67: Microwave-assisted synthesis of 4,7-dihetarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 68: Alternative synthetic route to 4,7-diheteroarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 69: Synthesis of 4-aryl-2-ethylthio-7-methylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 70: Microwave-assisted synthesis of 4-aminopyrazolo[1,5-a][1,3,5]triazine.
Scheme 71: Synthesis of pyrazolo[3,4-d][1,2,3]triazines from pyrazol-5-yl diazonium salts.
Scheme 72: Synthesis of 2,5-dihydropyrazolo[3,4-e][1,2,4]triazines.
Scheme 73: Synthesis of pyrazolo[5,1-c][1,2,4]triazines via diazopyrazolylenaminones.
Scheme 74: Synthesis of pyrazolo[5,1-c][1,2,4]triazines in presence of sodium acetate.
Scheme 75: Synthesis of various 7-diazopyrazolo[5,1-c][1,2,4]triazine derivatives.
Scheme 76: One pot synthesis of pyrazolo[5,1-c][1,2,4]triazines.
Scheme 77: Synthesis of 4-amino-3,7,8-trinitropyrazolo-[5,1-c][1,2,4]triazines.
Scheme 78: Synthesis of tricyclic pyrazolo[5,1-c][1,2,4]triazines by azocoupling reaction.
Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules
- Jan Podlesný,
- Lenka Dokládalová,
- Oldřich Pytela,
- Adam Urbanec,
- Milan Klikar,
- Numan Almonasy,
- Tomáš Mikysek,
- Jaroslav Jedryka,
- Iwan V. Kityk and
- Filip Bureš
Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235
- generation. The experimental data were completed by quantum-chemical calculations and structure–property relationships were elucidated. Keywords: calculations; diketopyrrolopyrrole; electrochemistry; electronic spectra; push–pull; third-harmonic generation; Introduction Known for more than 40 years
Graphical Abstract
Figure 1: General structure of investigated DPP derivatives 1–5.
Scheme 1: Synthesis of target DPP chromophores 1–5. (i) PdCl2(PPh3)2, Na2CO3, THF, H2O; (ii) PdCl2(PPh3)2, TH...
Figure 2: Thermograms of representative chromophores 4a and 4b.
Figure 3: Energy level diagram of the electrochemical (black) and DFT (red) derived energies of the EHOMO/LUMO...
Figure 4: UV–vis absorption spectra of chromophores 1a and 1b in 1,4-dioxane at a concentration of 1 × 10−5 M....
Figure 5: UV–vis absorption spectra of chromophores 1b–5b in 1,4-dioxane at a concentration of 1 × 10−5 M.
Figure 6: Typical THG dependences vs the fundamental energy density.
Figure 7: HOMO (red) and LUMO (blue) localizations in 1a (ethylhexyl chains truncated).
Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides
- Jan Szabo,
- Julian Greiner and
- Gerhard Maas
Beilstein J. Org. Chem. 2017, 13, 579–588, doi:10.3762/bjoc.13.57
- -methylation, the mesoionic system loses its betainic character and a 1,2,4-triazolium ion is formed. This is accompanied by the disappearance of the long-wavelength absorption in the electronic spectra, leaving colorless salts 8. Conclusion We have found that triaminoguanidine, generated from its
Graphical Abstract
Scheme 1: Reactions of aminoguanidines with carboxylic acids and acid chlorides. The structural formulae show...
Scheme 2: Threefold N-acylation of triaminoguanidinium chloride (1) with acyl chloride 2b.
Scheme 3: Reaction of 1,2,3-tris(benzylamino)guanidinium salts 4 and 5 with acyl chlorides to give 1,2,3-tris...
Figure 1: Molecular structure of 6b·2C2H5OH in the solid state, with numbering of atoms (ORTEP plot). Selecte...
Scheme 4: Protonation and methylation of 1,2,4-triazolium-3-aminides 7b,c.
Scheme 5: Catalytic hydrogenation/debenzylation of betaines 7.
Figure 2: Left: molecular structure of 8b in the solid state (OLEX2 plot). Right: crystal structure viewed al...
Figure 3: Left: solid-state structure of 9b·H2O (ORTEP plot). Right: centrosymmetric hydrogen-bonded dimer of...
Figure 4: Solid-state structure of mesoionic compound 7a (ORTEP plot); thermal displacement ellipsoids are dr...
Figure 5: UV–vis spectra of 7a–d in chloroform (c = 0.04 mmol L−1); λmax [nm] (ε [L mol−1 cm−1]): 7a: 350 (47...
Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties
- Dominik Urselmann,
- Konstantin Deilhof,
- Bernhard Mayer and
- Thomas J. J. Müller
Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194
- involved. Electronic spectra and oxidation potentials The electronic properties of the three thienyl-bridged oligophenothiazines 3 were experimentally investigated by absorption and emission spectroscopy and by cyclic voltammetry (Table 1). Cyclic voltammetry discloses the oxidation potential as an
Graphical Abstract
Figure 1: Thienyl-bridged oligophenothiazines as topological hybrids of (oligo)phenothiazines and 2,5-di(hete...
Scheme 1: One-pot bromine-lithium-exchange-borylation-Suzuki (BLEBS) synthesis of 7-bromo-substituted phenoth...
Scheme 2: Pseudo five-component Sonogashira-Glaser-cyclization synthesis of thienyl-bridged oligophenothiazin...
Figure 2: Cyclic voltammograms of compounds 3 (recorded in CH2Cl2, T = 293 K, electrolyte n-Bu4N+PF6−, Pt wor...
Figure 3: UV–vis (solid lines) and fluorescence spectra (dashed lines) of the thienyl-bridged oligophenothiaz...
Figure 4: DFT-calculated minimum conformer of the 2,5-bis(terphenothiazinyl)thiophene 3c (calculated with the...
Figure 5: Relevant Kohn–Sham FMOs contributing to the S1 states that are assigned to the longest wavelengths ...
Indenopyrans – synthesis and photoluminescence properties
- Andreea Petronela Diac,
- Ana-Maria Ţepeş,
- Albert Soran,
- Ion Grosu,
- Anamaria Terec,
- Jean Roncali and
- Elena Bogdan
Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81
- substituents in position 1: C6H4-m-OCH3, C6H4-p-t-Bu and C6H4-p-Br, respectively (Table 2). The use of methylene chloride or acetonitrile as solvents led to a similar trend of the electronic spectra depending on the nature of the substituents (Table 2, Figure 3, Figure S1 in Supporting Information File 1
- , UV–vis and fluorescence spectroscopy as well as mass spectrometry. Column chromatography of the crude product furnished the diastereoisomers as pure samples. The electronic spectra display two intense absorption bands ranging between 275–282 nm and 307–317 nm, while their photoluminescence spectra
Graphical Abstract
Scheme 1: Synthesis of dihydroindeno[1,2-c]pyran-3-ones 2 and 3.
Figure 1: Possible isomers of dihydroindeno[1,2-c]pyran-3-ones 2 and 3.
Figure 2: 1H NMR spectra (600 MHz, CDCl3) of isomers 2'b (top), 2''b (middle) and 3''b (bottom).
Figure 3: Normalized absorption spectra of dihydroindenopyrones 2'a–d, 2''b–d and 3''b, recorded in acetonitr...
Figure 4: Normalized UV–vis (left) spectra at excitation wavelengths and fluorescence (right) spectra of dihy...
Figure 5: Normalized solid-state and solution (acetonitrile) fluorescence spectra of diastereoisomers 2a–d.
Scheme 2: Synthesis of α-pyrones 4–6.
Figure 6: a) View of the asymmetric unit in the crystal of 6a, shown with 40% probability ellipsoids. b) View...
Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly
- Masahiko Iyoda and
- Masashi Hasegawa
Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175
- -TTF 16 showed two one-electron and one two-electron redox waves (Table 1), while other TTF dimers of 17–19 exhibited only two two-electron reversible redox waves corresponding to TTF/TTF•+ and TTF•+/TTF2+ at a normal scan rate (100 mV s-1). As shown in Table 1, however, steady-state electronic spectra
- ) showed a strong self-association, and electronic spectra of 23•+ and 232+ exhibited marked intermolecular charge resonance (CR) bands at λmax 2000 (br, ε 1500) and 2000 (br, ε 1700) owing to the face-to-face mixed valence interaction (Figure 8), and 233+ exhibited a typical Davydov blue shift (λmax 738
Graphical Abstract
Figure 1: Radially expanded TTF oligomers 1 and 2a,b.
Figure 2: TTF-calix[4]pyrrole 3 and its TNT and C60 complexes 4 and 5.
Figure 3: C3-symmetric TTF derivatives 6a,b and 7a–c.
Figure 4: Radially expanded TTF derivatives 8, 9, and 10a,b.
Figure 5: Amphiphilic TTFs 11–14 and 15a,b.
Figure 6: TTF dimers linked by σ-bond (16) and conjugated π-systems (17–19).
Scheme 1: Synthesis of star-shaped TTF trimers 22 and 23.
Figure 7: Projections of the molecular array of 22 in crystal structure (a) along with the c axis and (b) fro...
Figure 8: UV–vis/NIR spectra of 23, 23•+, 233+, and 236+.
Scheme 2: Synthesis of tris(TTF)[12]annulenes 28 and 29 and tris(TTF)[18]annulenes 30 and 31, together with h...
Figure 9: TTF-fused annulene 33 and radiannulenes 34 and 35.
Figure 10: Colors of 30 solutions a–d in toluene (0.025 mM) at various temperatures. (a) λmax: 511 nm, (b) λmax...
Figure 11: Solutions of 33. (a) In CS2, λmax: 608 nm. (b) In CH2Cl2, λmax: 577 nm. Reprinted with permission f...
Figure 12: Optical micrographs (1000× magnified) of fibers, prepared from 30 in THF–H2O 1:1, on a glass plate ...
Scheme 3: Star-shaped TTF oligomers 38–43.
Figure 13: Star-shaped TTF 10-mer 44.
Figure 14: Cyclic voltammograms of 38, 40, and 42 (0.1 mM) in benzonitrile with 0.1 M n-Bu4PF6 as a supporting...
Figure 15: Stepwise oxidation of (a) 38 (0.02 mM), (b) 40 (0.05 mM), and (c) 42 (0.03 mM) with incremental add...
Scheme 4: Pyridazine-3,6-diol-TTF 45 and its trimer 46.
Figure 16: CT-complex of 47 with TCNQF4.
Figure 17: (a) Star-shaped TTF hexamer 48. (b) Optical image of 48 fiber with a hexagonal structure. (c) Optic...
Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis
- Masashi Hasegawa,
- Junta Endo,
- Seiya Iwata,
- Toshiaki Shimasaki and
- Yasuhiro Mazaki
Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109
- –vis absorption spectra of 3 and PTDTA in CH2Cl2. (b) Normalized ECD spectra of (R)-PTDPA, (S)-PTDPA, (R)-3, and (S)-3 in CH2Cl2. CV of 3 (7.8 × 10−4 M) and PTDPA in PhCN. Electronic spectra of (a) 3 and its cationic species, and (b) PTDPA and its cationic states of PTDPA-(+1) and PTDPA-(+2). Synthesis
Graphical Abstract
Figure 1: TTF-substituted allenes 1–3.
Scheme 1: Synthesis of 3.
Figure 2: (a) ECD spectra of (R)-(−)-3 (3.5 × 10−5 M), (S)-(+)-3 (3.8 × 10−5 M), (R)-(−)-9 (3.0 × 10−5 M), an...
Scheme 2: Synthesis of chiral (R)-PTDPA and (S)-PTDPA.
Figure 3: (a) UV–vis absorption spectra of 3 and PTDTA in CH2Cl2. (b) Normalized ECD spectra of (R)-PTDPA, (S...
Figure 4: CV of 3 (7.8 × 10−4 M) and PTDPA in PhCN.
Figure 5: Electronic spectra of (a) 3 and its cationic species, and (b) PTDPA and its cationic states of PTDP...
Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores
- Huixin Jiang,
- Virginia Mazzanti,
- Christian R. Parker,
- Søren Lindbæk Broman,
- Jens Heide Wallberg,
- Karol Lušpai,
- Adam Brincko,
- Henrik G. Kjaergaard,
- Anders Kadziola,
- Peter Rapta,
- Ole Hammerich and
- Mogens Brøndsted Nielsen
Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104
- . However, the electronic spectra of the chemically generated radical cations (TTF-bridge-TTF•+) were reported to show clear intramolecular intervalence charge-transfer (IVCT) absorption bands with broad maxima around 1300–1400 nm [6]. We have previously found that when separating two TTFs by a cross
Graphical Abstract
Figure 1: TTF dimers with linearly or cross-conjugated bridging units, acyclic or cyclic bridging units.
Scheme 1: Synthesis of TTF dimers with alkyne bridges. TMEDA = N,N,N’,N’-tetramethylethylenediamine. MS = mol...
Scheme 2: Synthesis of TTF dimers with TEE and diethynylpyridine bridges.
Scheme 3: Synthesis of TTF dimer with radiaannulene core.
Figure 2: Molecular structure of 8 (top) and packing diagram (bottom). Crystals were grown from CH2Cl2/MeOH. ...
Figure 3: Bond angles for the cyclic core of 8 (X-ray crystal structure data).
Figure 4: Cyclic voltammograms obtained for the oxidation of compounds 1a ([10]), 2a ([10]), and 3b–8 (this work, ca....
Figure 5: Selected bis-TTFs from literature [20-23].
Figure 6: Cyclic voltammograms obtained for the reduction of compounds 1a, 2a, 6, and 8 in CH2Cl2 (0.1 M Bu4N...
Figure 7: One possible resonance form of the radical anion of 8 with a 14 πz aromatic core.
Scheme 4: Spin–spin interactions resulting from oxidation of TTFdimers.
Figure 8: In situ EPR−UV–vis–NIR cyclic voltammetry of 2b (1 mM) (a) potential dependence of difference vis–N...
Figure 9: In situ EPR−UV–vis–NIR cyclic voltammetry of 4 (0.4 mM): (a) potential dependence of difference vis...
Figure 10: Vis–NIR spectral changes observed during anodic oxidation of each TTF unit to cation radical within...
Figure 11: UV–vis–NIR absorptions of 1b (2.4 mM), 4 (3.5 mM), 5 (2.9 mM), and 8 (1.9 mM) in CH2Cl2 + 0.1 M Bu4...
Figure 12: In situ EPR−UV–vis–NIR cyclic voltammetry of 2b (1 mM) in the cathodic region: (a) potential depend...
Synthesis and spectroscopic properties of 4-amino-1,8-naphthalimide derivatives involving the carboxylic group: a new molecular probe for ZnO nanoparticles with unusual fluorescence features
- Laura Bekere,
- David Gachet,
- Vladimir Lokshin,
- Wladimir Marine and
- Vladimir Khodorkovsky
Beilstein J. Org. Chem. 2013, 9, 1311–1318, doi:10.3762/bjoc.9.147
- electron donating and accepting properties of this molecule. The geometry was optimized by using the semiempirical AM1 method and the electronic spectra were calculated by using the TD B3LYP/6-31G(d,p) method. The ionization potential (IP) and electron affinity (EA) were calculated at the B3LYP/6-31G(d,p
Graphical Abstract
Scheme 1: Synthesis and structures of 1,8-naphthalimides.
Figure 1: Normalized absorption (solid curves) and fluorescence (dashed curves) spectra of 4: (1) in cyclohex...
Figure 2: Normalized fluorescence spectra of 4 in ethanol (5 × 10−5 M): (solid line) neutral solution; (dashe...
Figure 3: Normalized fluorescence spectra of 4 in ethanol at different concentrations: (solid line) 10−4 M; (...
Scheme 2: Possible ionization and complexation of 4 in ethanol.
Figure 4: Fluorescence decay profile of 4 from a 10−5 M solution in ethanol (excitation at 450 nm, detection ...
Figure 5: Normalized one- and two-photon spectra of dye 4 in toluene. Solid curves: one-photon absorption and...
Figure 6: (a) HOMO and (b) LUMO of 4.
Figure 7: Fluorescence spectra of 4 ethanol (5 × 10−5 M) (dashed curve) before and after the addition of ZnO ...
Recent advances towards azobenzene-based light-driven real-time information-transmitting materials
- Jaume García-Amorós and
- Dolores Velasco
Beilstein J. Org. Chem. 2012, 8, 1003–1017, doi:10.3762/bjoc.8.113
- the millisecond time scale, based on chromophores with a push–pull configuration The electronic spectra of the stable trans isomer of type-I azoderivatives 1–4, display a high-intensity band peaking at ca. 355 nm, corresponding to the π→π* transition, and a weak broad-band signal at ca. 450 nm
Graphical Abstract
Figure 1: Some important families of photochromic compounds and their photochromic reactions.
Figure 2: Photochromism of azobenzene derivatives and energetic profile for the switching process.
Figure 3: General overview of the different types of azoderivatives presented in this review.
Figure 4: Changes in the electronic spectrum of a 3 cis-to-trans isomerising ethanol solution at 45 °C (Δt = ...
Figure 5: Chemical structure and thermal relaxation time in ethanol at 298 K, τ, for the slow thermally-isome...
Figure 6: Rotation and inversion mechanisms proposed for the thermal cis-to-trans isomerisation processes of ...
Figure 7: Effect of the presence of the electron-withdrawing cyano and nitro groups on the thermal relaxation...
Figure 8: Transient absorption generated by UV irradiation (λ = 355 nm) for azo-dyes 8 (right) and 9 (left) i...
Figure 9: Effect of the presence of a positively charged nitrogen as an electron-withdrawing group on the the...
Figure 10: Mechanism proposed for the thermal cis-to-trans isomerisation process for the push–pull azopyridini...
Figure 11: Comparison between the thermal relaxation time at 298 K, τ, for the azoderivative 4 (type-I) and th...
Figure 12: Solvent effect on the thermal relaxation time at 298 K, τ, for the type-II azophenols 11–13.
Figure 13: Transient generated by irradiation with UV-light (λ = 355 nm) for the type-II azophenol 12 in ethan...
Figure 14: Proposed isomerisation mechanisms for the thermal cis-to-trans isomerisation of the alkoxy-substitu...
Figure 15: Solvent effect on the thermal relaxation time at 298 K, τ, for the type-II ortho-substituted azophe...
Figure 16: Cooperative effect of the para- and ortho-hydroxyl groups in azophenol 17.
Figure 17: Effect of the poly-hydroxylation of the azobenzene core on the thermal relaxation time at 298 K, τ,...
Figure 18: Transients generated by irradiation with UV-light (λ = 355 nm) for the poly-substituted azophenol 18...
Figure 19: Effect of the introduction of electron-withdrawing groups in the position 4’ of the azophenol struc...
Figure 20: Transient absorptions generated by UV irradiation (λ = 355 nm) of azo-dyes 11 (type-II), 19 (type-I...
Figure 21: Effect of the introduction of the hydroxyl group in the position 2’ of the push–pull azo-dye on the...
Figure 22: Effect of the substitution of a benzene ring by a pyridine one on the thermal relaxation time in et...
Figure 23: Influence of the introduction of additional electron-withdrawing nitro groups in the pyridine ring ...
Figure 24: Chemical structure and thermal relaxation time in ethanol at 298 K, τ, for the type-III azoderivati...
Figure 25: Oscillation of the optical density of an ethanol solution of azo-dye 26 generated by UV-light irrad...
Synthesis of 3-(phenylazo)-1,2,4-triazoles by a nucleophilic reaction of primary amines with 5-chloro- 2,3-diphenyltetrazolium salt via mesoionic 2,3-diphenyltetrazolium- 5-aminides
- Shuki Araki,
- Satoshi Hirose,
- Yoshikazu Konishi,
- Masatoshi Nogura and
- Tsunehisa Hirashita
Beilstein J. Org. Chem. 2009, 5, No. 8, doi:10.3762/bjoc.5.8
- a hot-stage apparatus Yanaco MP 50533 and are uncorrected. Elemental analyses were carried out with a Perkin Elmer 2400 II CHNS/O. IR spectra were taken as KBr discs on a JASCO A-102 spectrometer. Electronic spectra were measured on a Hitachi U-3500 or a Shimadzu UV-2450 spectrophotometer. 1H NMR
Graphical Abstract
Scheme 1: Reaction of chlorotetrazolium 2 with benzylamine.
Scheme 2: Reaction of chlorotetrazolium 2 with triethylamine.
Scheme 3: Conversion of benzylaminotetrazolium 4a to 1,2,4-triazole 3a.
Scheme 4: Synthesis of chloroformazan 6 and its reaction with benzylamine and butylamine.
Scheme 5: Plausible reaction mechanism for the formation of 1,2,4-triazole 3.
