Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• charges, while at pH 5 both GCP moieties are also protonated, yielding 4 with four positive charges [18]. The concentration dependence of 4 according to its UV–vis spectrum at both, pH 5 and 7, was linear up to 2 × 10−5 M (Supporting Information File 1), supporting the presence of single, non-aggregated 4

• molecules in water. The absorption maxima and corresponding molar extinction coefficients (ε) are given in Table S1 (Supporting Information File 1). Heating of the aqueous solution of 4 up to 90 °C did not yield any significant changes in its UV–vis spectrum, suggesting that the chromophores are not

• involved in intra- or intermolecular stacking interactions. The excellent reproducibility of the UV–vis spectrum upon cooling back to room temperature (Figure S2, Supporting Information File 1) verified the chemical stability of the compound. The aqueous solution of the studied compound 4 was non

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• -difluoroanthracene. This strategy could be applicable for the synthesis of differently substituted 6,13-difluoropentacenes as well. Structures of pentacene and fluorinated pentacenes. UV–vis spectrum of F2PEN 5 in CH2Cl2. Retrosynthetic analysis of F2PEN 5. Synthesis of F2PEN 5. Decomposition of diol 13 in solution

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• -membered ring B. The large difference between the LUMO and HOMO leads to an intramolecular charge transfer, resulting in broad absorption bands in the UV–vis spectrum (Figure 3a) [36]. In addition, the LUMO energy of 1 (−2.98 eV) is significantly lower than that of 6 (−2.38 eV), which is responsible for

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• dialkoxides (Figure 6b). In contrast, 5c exhibited different features in both UV–vis and emission spectra from the other two. In the UV–vis spectrum of 5c, the splitted sharp absorptions at 266 and 287 nm and a broad band at 320 nm together with a relatively strong broad band at 409 nm are visible. The

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• be insoluble in water. We therefore dissolved 4 in DCM to obtain the UV–vis spectrum of the neutral form. Addition of TFA to this solution produced the corresponding azonium ion, and the spectra of the neutral and azonium forms of 4 are shown as solid lines in Figure 2. Observed absorption maxima

• neutral pH, creating a doubly charged species. As anticipated, compound 5 was found to be much more water-soluble than 4. The UV–vis spectrum of 5 at a neutral pH value is shown in Figure 4. Irradiation with blue light at 440 nm produced the PSS (dotted line). Thermal reversion from the cis isomer was

• monitored by UV–vis spectroscopy, recording a UV–vis spectrum every 3 minutes, and a half-life of 12.6 minutes was obtained. The formation of the azonium ion of 5 in aqueous solution was explored thereafter. Addition of hydrochloric acid to a neutral solution of 5 was carried out. Spectra at different pH

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

• Heather J. Lacey,
• Cameron L. M. Gilchrist,
• Andrew Crombie,
• John A. Kalaitzis,
• Daniel Vuong,
• Peter J. Rutledge,
• Peter Turner,
• John I. Pitt,
• Ernest Lacey,
• Yit-Heng Chooi and
• Andrew M. Piggott

Beilstein J. Org. Chem. 2019, 15, 2631–2643, doi:10.3762/bjoc.15.256

• -resolution positive electrospray ionisation mass spectrometry (HRESI(+)MS) analysis of nanangenine A (1) revealed an adduct ion ([M + Na]+ m/z 305.1363) indicative of a molecular formula C15H22O5 requiring five double bond equivalents (DBE). No distinguishing absorption maxima were observed in the UV–vis

• spectrum, while absorptions at 3354 and 1738 cm−1 in the IR spectrum were indicative of hydroxy and carbonyl groups, respectively. The 13C NMR data for 1 (Table 1) indicated the presence of one carbonyl carbon (δC 179.3, C-11) and two olefinic carbons (δC 128.2, C-7 and δC 131.1, C-8), accounting for two

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• of Stefan Hell, MPI for Medical Research Heidelberg) for measurement of the UV–vis spectrum of 30c.

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

• Eric W. Webb,
• Jonathan P. Moerdyk,
• Kyndra B. Sluiter,
• Benjamin J. Pollock,
• Amy L. Speelman,
• Eugene J. Lynch,
• William F. Polik and
• Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

• assignment. UV–vis spectra taken of eLW solutions generated by bulk electrolysis in acetonitrile and acetonitrile-d3 were compared against photoirradiated (pLW) solutions. No difference was observed in the UV–vis spectrum of the LW isomer prepared from either photolysis or electrolysis of solutions of 1b (as

• photolyzed solution (4a) versus 529 nm for the electrolyzed (5a). Similarly, for 4b and 5b, the photolyzed λmax in acetonitrile was 558 nm versus 549 nm for the electrogenerated and was 564 nm versus the electrogenerated 550 nm in acetonitrile-d3. The differences in the UV–vis spectrum of about 10 nm between

• would be expected to be noticeable but not large. Observation of no difference in the UV–vis spectrum of the LW isomer prepared from either photolysis or electrolysis of solutions of 1b (able to only form one LW isomer, 2b) supports the formation of two different LW isomers for 3a,b rather than

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• absorption maximum, the UV–vis spectrum of 2b developed a more complex structure with further illumination. The initial spectrum did not restore, neither thermally by standing in the dark nor photochemically when exposed to daylight. Regarding 2f, 254 nm radiation was obligatory to obtain changes in the UV

• hit compound GW435821X (2a). (Left) UV–vis spectrum of 2b 50 µM in 5% DMSO (v/v) in assay buffer after varying durations of irradiation with 254 nm and 365 nm, respectively. (Right) UV–vis spectrum of 2f 50 µM in 5% DMSO (v/v) in assay buffer after varying durations of UV radiation. (Left) LC

• –HRMS analysis of 2f after varying durations of irradiation with 254 nm. Calculated and experimental absorption spectra of compounds (E)-2b-B (A), (Z)-2b-A (B), and products 8a (C) and 8b (D). Oscillator strengths (green sticks) correspond to the ADC(2)/COSMO calculation. (Left) UV–vis spectrum of 11

A golden opportunity: benzofuranone modifications of aurones and their influence on optical properties, toxicity, and potential as dyes

• Joza Schmitt and
• Scott T. Handy

Beilstein J. Org. Chem. 2019, 15, 1781–1785, doi:10.3762/bjoc.15.171

• . In this study, the influence of substitution in the benzofuranone ring on the UV–vis spectrum is explored, as well as an initial screening of their toxicity and a qualitative preliminary study of their potential to act as fabric dyes. Keywords: aurone; dyeing; dyes; substitution effect; toxicity; UV

• –vis spectrum; Introduction Aurones are a fascinating minor sub-family of the flavonoid natural products [1][2]. While they feature the same C15 composition as other flavonoids, the skeleton is quite different, featuring a benzofuranone connected to an aromatic ring via an exocyclic alkene. This

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• -resolution mass spectrometry (HRMS, Supporting Information File 1, Figures S19–S21). Photophysical properties The photophysical properties were investigted by UV–vis absorption and fluorescence spectroscopy, as well as through fluorescence decay measurements. As shown in Figure 1a, the UV–vis spectrum of P5A

Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• be followed by a decrease of the trans-absorption maximum at around 350–400 nm and an increase in absorption at around 450–500 nm in the UV–vis spectrum representing the cis-isomer (Figure 1, black arrows). The absorption bands of the trans and cis-isomers of compounds 12a, 16c, and 16d overlap to

• indicated wavelength or by thermal relaxation (5a, 5b, 12a, 16a–d, 23, and 28). The irradiation times were determined by following the UV–vis spectrum upon isomerization until no more changes in absorption were observed and the photostationary state (PSS) was reached. The points of intersection in the

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• charge, and the carbon atom has a negative charge [23]. It is assumed that after the formation of such complexes, they initiate the metathesis polymerization of dicyclopentadiene. In the UV–vis spectrum of Cp2TiCl2, two maxima are observed at 388 and 516 nm. It is known that when a solution of AlEt2Cl is

Oxidative and reductive cyclization in stiff dithienylethenes

• Michael Kleinwächter,
• Ellen Teichmann,
• Lutz Grubert,
• Martin Herder and
• Stefan Hecht

Beilstein J. Org. Chem. 2018, 14, 2812–2821, doi:10.3762/bjoc.14.259

• (Epc = −0.530 V) during the return scan (Figure 2d). At the same time the reduction waves corresponding to the closed isomer, as observed in the CV experiment with high scan rates (Figure 1), disappear. Furthermore, the UV–vis spectrum recorded in the SEC after reduction is an overlay of that of the

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• : UV–vis spectrum of the degassed [Ir] + 1,3,5-TMB mixture (solution A) in ACN. Blue and red lines: Absorption spectra averaged over 10–30 ns after 355 nm laser-pulse with red being derived from the [Ir] solution I and representing the emission spectrum of the catalyst. Whereas, the blue line was

Graphitic carbon nitride prepared from urea as a photocatalyst for visible-light carbon dioxide reduction with the aid of a mononuclear ruthenium(II) complex

• Kazuhiko Maeda,
• Daehyeon An,
• Ryo Kuriki,
• Daling Lu and
• Osamu Ishitani

Beilstein J. Org. Chem. 2018, 14, 1806–1812, doi:10.3762/bjoc.14.153

• filtrates were collected and concentrated to a volume of 30 mL. The amount of the ruthenium complex absorbed was calculated based on the UV–vis spectrum of the filtrate, using Equation 1: where Abefore and Aafter are the absorbance of the solution before and after the adsorption procedure, respectively, and

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• distilled off from the resulting mixture in vacuo. The residue was purified by column chromatography over SiO2 (ethyl acetate/cyclohexane 1:1) to obtain the product. Time-dependent 1H NMR spectra of the air-exposed complex B. ORTEP drawing (50% probability) of complex B. UV–vis spectrum of complex B was

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• for. However, even at this small ratio mentioned above, DMSO significantly absorbs light at <240 nm, hampering an accurate collection of data in the short-wavelength region. It is essential to check the dependence of the ligand’s UV–vis spectrum on its concentration in the experimental conditions

• UV–vis spectrum and if applicable, ECD spectrum at various temperatures, can give useful information about intra- or intermolecular interactions of a ligand. However, an ECD spectrum depends on the temperature in several ways other than affecting aggregation, for example by changing conformational

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

• Vivek Poonthiyil,
• Thisbe K. Lindhorst,
• Vladimir B. Golovko and
• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2

• peak in the UV–vis spectrum are typically unchanged. However, in this case, when the water-insoluble ligand 33 was used, the solution turned purple (Supporting Information File 1, Figure S4), and the SPR peak shifted to a higher wavelength (523 nm to 541 nm) and became broader (Supporting Information

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• –vis spectrum, do not aggregate in solution. These dyes are expected to be developed into medical imaging probes. Phthalocyanine is expected to be used not only as a biological imaging agent but also in cancer treatment. Photodynamic therapy (PDT) is a laser cancer therapy that introduces organic dyes

• ][91] or a peptide [92]. For example, TFEO-Pcs conjugated with peptides (15) have been reported [93]. A3B type TFEO-Pc was successfully condensed with peptides by palladium-catalyzed cross-coupling reactions in good yield (Scheme 5). These TFEO-Pc-peptide conjugates, which show a sharp Q band in the UV

β-Cyclodextrin- and adamantyl-substituted poly(acrylate) self-assembling aqueous networks designed for controlled complexation and release of small molecules

• Liang Yan,
• Duc-Truc Pham,
• Philip Clements,
• Stephen F. Lincoln,
• Jie Wang,
• Xuhong Guo and
• Christopher J. Easton

Beilstein J. Org. Chem. 2017, 13, 1879–1892, doi:10.3762/bjoc.13.183

• withdrawn, its UV–vis spectrum was measured and the sample was then returned to the receiving solution. The dye concentration in the receiving solution was calculated by reference to its molar absorbance spectrum determined under the same conditions. Each dye solution composition is given in Table S1

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• ] versus 1/[AcO−]2 confirming a 1:2 binding ratio between R1 and AcO− ion as represented in Figure 6. The necessity of two AcO― ions in the binding process could be justified by the fact that a formation of the dimer [(CH3COO)2H]− is more favored than the formation of CH3COOH alone. The UV–vis spectrum of

• circuit constituting “INHIBIT” functions at the molecular level using F− and Hg2+ ions as chemical input. The UV–vis spectrum of receptor R1 (4.5 × 10−5 M in DMSO) in the presence of fluoride as anion resulted in an output at 477 nm exhibiting a simple “YES” response. In the presence of Hg2+ as third

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• present in the as-cast films of BQR or the thermally annealed films (measured at room temperature). The BQR thin films were annealed up to 220 °C to probe the effect on the UV–vis spectrum (spectrum collected at room temperature after cooling) of cycling the BQR thin film up to the NLC phase change

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• bathochromically by only 3 nm. The UV–vis spectrum of the 4′-azulenyl-substituted terpyridine 4a resembles the absorption maximum of the terpyridine core found below 300 nm, but the longest-wavelength absorption maximum is shifted to 377 nm. The absorption bands of the azulene-containing terpyridines are

• + structural motif. A similar visible-change profile was observed in the case of CdCl2 titration, but here the analysis of the titration curve showed a different profile (Figure 9). First, a closer look at the resulting UV–vis spectrum after cadmium(II) complex formation shows that the absorption maximum is

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• constant indicating the stability of the Fc units. Isosbestic points are observed at 337 and 500 nm corroborating the clean conversion of W(CO)5(E-2) to E-3 without long-lived soluble intermediates (Supporting Information File 1, Figure S28). The final UV–vis spectrum after 6 h closely resembles that of

• isomer in accordance with the IR data of W(CO)5(E/Z-8) [46]. The carbonyl region of IR spectra of W(CO)5(E-2) are in accordance with those of Cr(CO)5(E-2) [27] and related amino(ferrocenyl)carbene(pentacarbonyl)tungsten complexes W(CO)5(E-14R) (R = Me, Et, n-Pr [23], n-Bu [25], n-Pent [21]). The UV–vis

• spectrum of W(CO)5(E-2) (Supporting Information File 1) is similar to that of Cr(CO)5(E-2) [27] and to those of carbene(pentacarbonyl)metal complexes (Cr, W) [60][61]. Thermolysis of W(CO)5(E-2) in refluxing toluene gives imine E-3 [43] after ca. 24 h in almost quantitative yield, as monitored by 1H NMR