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Search for "UV–vis spectra" in Full Text gives 250 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules
Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190
- macroscopic as well as on the molecular level, even the most efficient switch is useless, if no observable output is generated which helps to detect the switching process [30]. A simple “read out” is provided by the optical properties of TTF in its different switching states. For example, UV–vis spectra of
- changes. UV–vis spectra and photographs of TTF 2 in its three stable oxidation states (black line = 2, orange line = 2●+, blue line = 22+). Structure and conformations of two TTF dimers in solution, the mixed-valence and the radical-cation dimer. (a) The isomerism problem of TTF. (b)–(d) Major synthetic
Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates
Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173
- solutions dried on the surface of the KBr disc. Melting points were measured using a Stuart SMP10 apparatus. UV–vis absorbance spectra The UV–vis-spectra were recorded on a Lambda 35 UV/VIS spectrophotometer (Perkin Elmer Instruments) in an optical cell with 1.0 cm light pass at 298 K. Dynamic light
Efficient catenane synthesis by cucurbit[6]uril-mediated azide–alkyne cycloaddition
Beilstein J. Org. Chem. 2018, 14, 1846–1853, doi:10.3762/bjoc.14.158
- ; bisolated yield by preparative HPLC. Supporting Information Supporting Information File 290: Detailed experimental procedures and characterization data (MS, MS2, 1H and 13C NMR and UV–vis spectra). Acknowledgements The work described in this paper was supported by the Croucher Foundation and a grant from
First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones
Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156
- spectra were registered with a FTIR NEXUS spectrometer (as film or KBr pellets). UV–vis spectra were recorded using a UV–vis JASCO V-630 spectrophotometer. Melting points were determined in capillaries with a Stuart SMP30 apparatus with automatic temperature monitoring. Starting materials: 1,4
Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials
Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127
- -); ESIMS 189.0878 (calcd for C8H8N6 + H+, 189.0883). UV–vis spectra were recorded on a Bruker DU 800 spectrophotometer, equipped with a Peltier thermostatic apparatus. FTIR spectra (nujol) were recorded on an Agilent Technologies Cary 630 FTIR spectrometer. NMR spectra were acquired on a Bruker Avance II
Polysubstituted ferrocenes as tunable redox mediators
Beilstein J. Org. Chem. 2018, 14, 1004–1015, doi:10.3762/bjoc.14.86
- IR-SEC experiments, the esters 1–4 were also probed by UV–vis-SEC investigations. The UV–vis spectra of 1–4 recorded in dichloromethane show the ferrocene ligand field absorption band at λmax = 444, 449, 455 and 457 nm, which is typically around λmax ≈ 440–490 nm [66][70][79][80] (Figure 5a). The
- Information File 1). Probably, precipitation of the poorly soluble tetraester 4+ could be responsible for this effect, as already suggested for the IR-SEC experiments of 4/4+. On the other hand, isosbestic points are observed in the UV–vis spectra upon re-reduction of 4+ to 4 (Figure S31, Supporting
- dependency of the energy on the number n of methoxycarbonyl substituents can be found than for the ligand field band of the ferrocenes 1–4 (Figure 6b). The lowest energy band (band I) in the UV–vis spectra of 1+–4+ is assigned to ligand-to-metal charge transfer (LMCT) transitions [79][81][82][83]. The bands
An air-stable bisboron complex: a practical bidentate Lewis acid catalyst
Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48
- experimental procedures, copies of 1H and 13C NMR spectra, UV–vis spectra as well as the X-ray crystallography. Supporting Information File 32: CIF of bisborane complex B. Acknowledgements Funding by the BMEL (Federal Ministry of Food and Agriculture) within the project FOREST (22403116) and by the CMBlu AG
Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial
Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5
- mechanism between the various π→π* transitions of regularly arranged chromophores [14] (Figure 3, top). Chiroptical properties and ECD spectra of particular DNA or RNA sequences are therefore strongly dependent on the polynucleotide secondary structure [15], at variance to the common UV–vis spectra of the
- richer in bands than a typical ECD spectrum (just like IR spectra vs UV–vis spectra) [1][4][36]. Nowadays, density functional theory (DFT) allows a calculation of the VCD spectrum of a chiral molecule, which then can be compared with the measured VCD spectrum and by this the absolute configuration (AC
Halogen-containing thiazole orange analogues – new fluorogenic DNA stains
Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283
- . Interactions of the new derivatives of TO with dsDNA have been investigated by absorption and fluorescence spectroscopy. The longest wavelength absorption bands in the UV–vis spectra of the target compounds are in the range of 509–519 nm and these are characterized by high molar absorptivities (63000–91480
- , 3a, and 3b were commercially available and were used as supplied. Melting points were determined on a Kofler apparatus and are uncorrected. NMR spectra were obtained on a Bruker Avance III 500 DRX 600 MHz spectrometer in DMSO-d6. UV–vis spectra were measured on a Unicam 530 UV–vis spectrophotometer
Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics
Beilstein J. Org. Chem. 2017, 13, 2428–2441, doi:10.3762/bjoc.13.240
- (conversion of 11i to 12i). Or LiOH (3 equiv), MeOH/H2O (2:1), 0 °C, 30 min. B) UV–vis spectra of propargylamines 11 and α,β-unsaturated imines 12. C) X-ray crystal structure analysis of propargylamine 11i and α,β-unsaturated imine 12i. Preparation of N-sulfinyl propargylamines 7 with aliphatic side chains.a
Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines
Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224
- mononuclear phthalocyanine does not show any aggregation effect [74]. The aggregation behavior can be estimated from the UV–vis spectra. Phthalocyanine, which is free from aggregation, exhibits a sharp Q band, but the Q band of aggregated phthalocyanine is broadened and shifts to the shorter wavelength region
- and H-subPc heterodimer. Since the UV–vis spectra of a heterodimer are the sum of the absorption spectra of the respective units, it is suggested that each unit has an independent π-conjugate system. On the other hand, the fluorescence quantum yield decreased as a whole and the fluorescence derived
- of axial ligand substituted subphthalocyanine hybrid dyes. Energy transfer between subphthalocyanine units. Structure of phthalocyanine and subphthalocyanine benzene-fused homodimers. X-ray crystallography of Pc-subPc (left) and UV–vis spectra of benzene-fused dimers. Synthesis of trifluoroethoxy
Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives
Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203
- analysis of UV–vis spectra could also provide qualitative information on the formation of inclusion complexes in solution. The addition of guests 7–10 to a solution of clips 1–5 turns the colourless solution to yellow, and a new wide absorption band (370–560 nm) appears. The new band was assigned to a
- , Supporting Information File 1). Typical changes in the UV–vis spectra during the titration of clip 2 with paraquat (7) are presented in Figure 4. The data obtained for molecular clips 1–3 are best described by titration curves corresponding to 1:1, and for clips 4 and 5 – to 1:1 and 1:2 complexes. Stability
- , v/v) of (a) free host 3, (b) 3 and 1.0 equiv of 7, and (c) free guest 7. The changes observed in the UV–vis spectra during the titration of clip 2 with paraquat (7) in acetonitrile at 20 °C. The labels near each plot correspond to the equivalents of paraquat (7) added. Stability constant dependence
β-Cyclodextrin- and adamantyl-substituted poly(acrylate) self-assembling aqueous networks designed for controlled complexation and release of small molecules
Beilstein J. Org. Chem. 2017, 13, 1879–1892, doi:10.3762/bjoc.13.183
- spectroscopy The UV–vis spectra were recorded with a Cary-Varian 5000 UV–vis spectrophotometer using 1 cm path length matched quartz cells. All UV–vis titrations were performed in aqueous Na2HPO4/KH2PO4 buffer at pH 7.0 and I = 0.10 mol dm−3 at 298.2 K. For the β-CD/dye titrations, 50 mm3 aliquots of a β-CD
Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins
Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152
- tatraarylated derivatives. The investigation of the UV–vis spectra of the arylated monophenylporphyrins 3–9 disclosed that they possess almost identical absorption maxima but somewhat differ in extinction values primarily due to the different sharpness of the bands (Table 4). The Soret band at 406 nm is
- bromophenylporphyrinate. The UV–vis spectra of diphenylporphyrins 13–15 (Table 4) possess absorption bands in the same region as their monophenyl analogues 3–9, but all maxima are slightly red-shifted. It fully corresponds with the absorption bands of the bis(4-bromophenyl)porphyrin 11 (λmax 575 (lgε 3.16), 540 (lgε 3.38
Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates
Beilstein J. Org. Chem. 2017, 13, 1350–1360, doi:10.3762/bjoc.13.132
- )-one system. The keto–enamine arrangement in 3 is capable of specific binding of Cu(II) ions like in 4, which was proved by red shifts in the UV–vis spectra [6][7][8]. The pseudo ring can also accommodate BF2 moiety, yielding compounds like 5 with interesting fluorescent properties [9][10]. Compounds 3
Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications
Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87
- . The UV–vis spectra of annealed films of the polymers at 130 °C show an apparent red shift in the onset absorption because of an increased aggregation of the polymer chains upon heating. The optical band gaps of P1, P2, and P3 were calculated from the onset of the absorption as 1.95 eV, 1.93 eV and
Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides
Beilstein J. Org. Chem. 2017, 13, 579–588, doi:10.3762/bjoc.13.57
- , the δ(C-5) value in 7d corresponds to the deshielding α-effect of a methyl group, if one takes the δ-value of the unsubstituted C-5 carbon nucleus in II as a reference. The UV–vis spectra of 7a–d are presented in Figure 5. One notes an increasingly bathochromic shift of the long-wavelength absorption
- , N4H···N11 2.061(1) Å; <(N4–H···N11) 168.7(2)°. UV–vis spectra of 7a–d in chloroform (c = 0.04 mmol L−1); λmax [nm] (ε [L mol−1 cm−1]): 7a: 350 (4710); 7b: 350 (5080); 7c: 430 (3510); 7d: 300 (2670). Reactions of aminoguanidines with carboxylic acids and acid chlorides. The structural formulae shown
Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands
Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55
- jellyfish resembling receptors (b) [11][16]. UV–vis spectra of 5c (50 μM solution in MeCN) before and after the addition of 5 equiv of metal perchlorates. Example of Pd-catalyzed amination for modification of bile acid derivatives. Synthesis of 24-aminocholanols. Synthesis of 24-arylaminocholanols by Cu
Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications
Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25
- corresponding UV–vis spectra are shown in Supporting Information File 1, Figures S19 and S20. There was no remarkable colorimetric response in the presence of the other cations tested in the current study. In case of receptor R2 no color change was observed in the presence of the cations implying its role as an
Efficient access to β-vinylporphyrin derivatives via palladium cross coupling of β-bromoporphyrins with N-tosylhydrazones
Beilstein J. Org. Chem. 2017, 13, 195–202, doi:10.3762/bjoc.13.22
- -brominated porphyrin 1 and N-tosylhydrazones 2a–c. Results obtained in the palladium-catalyzed cross-coupling reactions between β-brominated porphyrin 1 with N-tosylhydrazones 2a–c. Supporting Information Supporting Information File 46: Copies of NMR, HRMS(ESI) and UV–vis spectra of the new derivatives
- ) using CHCl3 as solvent. For the reactions under MW irradiation a CEM Microwave Synthesis System Discover SP was used, under constant magnetic stirring (controlled by the microwave equipment) by employing an irradiation power of 200 W till the reaction temperature (120 °C) was achieved. The UV–vis
- spectra were recorded on an UV-2501 PC Shimadzu spectrophotometer using CHCl3 as solvent. Flash chromatography was carried out using silica gel (230–400 mesh) and preparative thin-layer chromatography was carried out on 20 × 20 cm glass plates coated with silica gel (1 mm thick). The reactions were
3D printed fluidics with embedded analytic functionality for automated reaction optimisation
Beilstein J. Org. Chem. 2017, 13, 111–119, doi:10.3762/bjoc.13.14
- selected because it would run smoothly at room temperature, and a mild solvent mixture such as methanol and water (MeOH/water) could be used with the less solvent-compatible parts. Differences between the UV–vis spectra of the starting material and the product can be used to follow the reaction
Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases
Beilstein J. Org. Chem. 2016, 12, 2588–2601, doi:10.3762/bjoc.12.254
- obtained from commercial suppliers and were used without further purification. The NMR and UV–vis spectra were recorded on Brucker Avance 500-DRX (Bruker, Germany) and Carry 100 spectrometers (Varian, USA), respectively. TLC was performed on TLC aluminium sheets covered with silica gel 60 F254. Low
Methylenelactide: vinyl polymerization and spatial reactivity effects
Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232
- ) with AIBN (A) and without initiator (B). UV–vis spectra of the reaction mixture with DPPH radical at the beginning (violet line, 0.23 mM) of the self-initiated polymerization of MLA and after 15 h (yellow line) in a range from 380–800 nm (cMLA = 1.8 mol L−1, 70 °C). Copolymer composition curves for the
High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension
Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223
- at around 570 nm, therefore indicating that the underlying packing structures are not significantly altered through side-chain substitution. To better understand the annealing process UV–vis spectra have been replotted for each material, see Figure 6 (and Supporting Information File 1, Figures S9.1
- those used to collect the UV–vis spectra above, with selected graphs shown in Figure 7, and extracted data in Table 2. The full spectra are presented in Supporting Information File 1, Figure S9.3. The as-cast films do not contain simple symmetric emission bands, indicating a significant level of
- obtain the UV–vis spectra, were heated to above the NLC phase change temperature, and collected fluorescence emission spectra are shown in Figure 10. It is clear that when the thin films are heated to 220 °C, i.e., above the NLC phase change temperature, a second blue shifted peak appears at 730 nm
Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties
Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194
- S4). In addition this behavior underlines that no aggregation of the molecules has to be taken into account at the concentration level of absorption and emission spectroscopy. In the UV–vis spectra, most characteristically, four absorption bands are found, three at shorter wavelengths arising from
- match of experimentally and computationally determined absorption bands cannot be expected for conformationally flexible complex molecules with extended π-conjugation, the trend of the longest wavelength absorption bands from the UV–vis spectra is correctly reproduced. Furthermore, for all three methods
- oligophenothiazines 3a, 3b, and 3c, computed UV–vis spectra of ZINDO-CI and TD-DFT (B3LYP, CAM-B3LYP) calculated structures of 3a, 3b, and 3c, computed FMOs (frontier molecular orbitals) of the calculated structures 3a, 3b, and 3c. Supporting Information File 272: Experimental and analytical data. Acknowledgements
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