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

• absorbance at 440 nm was diminished and that at 330 nm slightly enhanced (Figure 3). An estimated PSS of ca. 60% Z-isomer was calculated as described in the Experimental section. Thermal relaxation from the PSS was monitored by UV–vis spectroscopy, recording a spectrum every minute. As shown in Figure 3, a

• 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

• , 2H), 4.11 (s, 6H), 3.45 (m, 8H), 3.00 (m, 8H); 13C NMR (126 MHz, DCM-d2) δ 158.9, 154.0, 140.2, 123.0, 111.5, 107.2, 66.9, 57.3, 45.1; HRMS (m/z): [M + H]+ calcd for C22H29Br2N6O2, 567.0719; found, 567.0713. UV–vis spectroscopy UV–vis spectra were recorded on a PerkinElmer LAMBDA 35, Shimadzu UV

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• optical bench equipped with a 150 W Hg–Xe lamp and a monochromator [40]. Samples (40 μM) were stirred during the irradiation and the amount of converted material was determined at 2 min intervals by UV–vis spectroscopy following the disappearance of the band at 362 nm. The error in the photoreaction

In search of visible-light photoresponsive peptide nucleic acids (PNAs) for reversible control of DNA hybridization

• Lei Zhang,
• Greta Linden and
• Olalla Vázquez

Beilstein J. Org. Chem. 2019, 15, 2500–2508, doi:10.3762/bjoc.15.243

• the PNAs, UV–vis spectroscopy of 20 μM solutions in phosphate buffer (10 mM NaH2PO4, 150 mM NaCl, pH 7.4) confirmed that PNA incorporation did not significantly affect the photochromism (Figures S24, S20, S30 and S33, Supporting Information File 1). This verifies the integrity of the chromophores

• complementary DNA. For this purpose, we decided to measure thermal melting curves. Beforehand we verified the photostability of cis-PNA12(oF4Azo) (3) in the temperature ramp from 20 °C to 90 °C by UV–vis spectroscopy. We observed that the cis-isomer was always stable during the whole temperature range (Figure

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

• small molecule organic electrochromism [6][7][9]. One example that combines photochromic and electrochromic behavior (the latter of an unusual sort) is the class of perimidinespirohexadienones 1 (PSHDs) whose synthesis, electrochemistry and UV–vis spectroscopy were reported by Minkin and co-workers [10

• peaks was consistent with UV–vis spectroscopy that indicated a significant amount of a LW isomer upon solvation, and repetitive electrochemical scans exhibited the anticipated growth of the LW reduction–oxidation peaks as more of the LW isomer was generated electrochemically (Figure 3b, solid blue

• electrochemical grade and used as received. Photochromes 1a,b were prepared according to the literature [10]. Photochromes 3a,b were prepared as we previously reported [21]. Instrumentation Photochemical irradiations and UV–vis spectroscopy were performed as previously described [21] on 3 mL or 4 mL argon-purged

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• spectroscopy. Photoisomerizations (followed by UV–vis spectroscopy) CHCl3 solutions of products (Z)-1d and stiff stilbene were irradiated after degassing by argon bubbling for 15 min. As reaction vessels, 10 mm quartz UV–vis cuvettes were used. The course of isomerization was assessed by UV–vis spectroscopy

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

• are oxidized to 2- and 4-azaphenantrene (not shown), respectively [50]. Photochemistry of compounds 2b and 2f was investigated via UV–vis spectroscopy, LC–HRMS and NMR spectroscopy. Compound 2b represents the core structure of the azastilbenes investigated, whereas in 2f the influence of ortho

• methylation was intended to be examined. For UV–vis spectroscopy 50 µM solutions in 5% DMSO (v/v) in enzyme assay buffer were used, as this reflects the enzyme assay conditions. However, for LC-HRMS and NMR analysis, a higher concentration of 10 mM in methanol was necessary to receive reliable chromatograms

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• . Upon complexation with a halide, the planar aromatic ring adopted a heavily pinched boat conformation, a result consistent with theoretical prediction [49]. We also examined the host–guest interaction in solution phase employing NMR and UV–vis spectroscopy and fluorescence technology. Unfortunately

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• were computed by density functional theory modelling (DFT) and characterized through UV–vis spectroscopy and cyclic voltammetry (CV) measurements. Finally, we report preliminary results obtained using these functional dyes as photosensitizers in dye-sensitized solar cells (DSSCs). Keywords: boron

• were investigated using UV–vis spectroscopy, and we show that they can absorb light up to 900 nm in solution and 1000 nm in solid state, after grafting on anatase-TiO2 mesoporous films. The cyclic voltammetry (CV) measurements indicate that the compounds have HOMO and LUMO energy levels suitable for an

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• [44]. Furthermore, the ζ-potential is known to be highest in deionized water and highly pH-dependent [45]. The ligand exchange reaction was also analyzed by UV–vis spectroscopy (Figure 1b). The synthesized [CTAB]AuNR show the two expected absorption maxima at λ = 525 nm for the TSPR band and at λ

• light-responsive assembly was further investigated via UV–vis spectroscopy (Figure 2c and d). The spectrum measured after injection of dAAP shows a broadened LSPR maximum with a red shift of λ = 7 nm while the TSPR band remains unchanged. This indicates longitudinal coupling of AuNR as a result of the

• ). Even upon addition of rather high concentrations of mAAP (100 µM) no strong shift can be observed by UV–vis spectroscopy, indicating that supramolecular cross-linking is essential for end-to-end assembly of the AuNR. Conclusion In summary, we reported a supramolecular system based on the reversible

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

• Qichao Zhang,
• Jian Lv and
• Sanzhong Luo

Beilstein J. Org. Chem. 2019, 15, 1304–1312, doi:10.3762/bjoc.15.129

• formation of tritylium ions (Scheme 2a). The stimulated trityl cation generation was probed by UV–vis spectroscopy. As shown in Figure 1a, when treated with different Lewis acids, trityl phosphate TP showed a variable tendency to dissociate into the free tritylium ion pair with InBr3 as the most active

Bambusuril analogs based on alternating glycoluril and xylylene units

• Tomáš Lízal and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2019, 15, 1268–1274, doi:10.3762/bjoc.15.124

• bind inorganic anions with high binding affinity and selectivity in both organic media and water [13][14]. Previously we used bambusurils to recognize and quantify anions in their complex mixtures at sub-micromolar concentrations by means of NMR [15]. However, sensing of anions by less expensive UV–vis

• spectroscopy was not possible due to the low absorption of bambusurils within the UV–vis region. Therefore, we decided to investigate the synthesis of bambusuril derivatives and analogs containing chromophores in their structure. Initially we tested post-macrocyclic functionalization resulting in bambusurils

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

• filtrate. The filtrate was passed through a silica gel column using 1:3 ethyl acetate/hexanes as the mobile phase. Fractions containing porphyrin, as determined by thin-layer chromatography and UV–vis spectroscopy were combined and the solvent was removed using a rotary evaporator. meso-Tetrakis[2,4,6

Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• were proved by NMR spectroscopy, elemental analysis, IR and UV–vis spectroscopy. Photophysical properties Steady-state absorption and emission spectroscopy Next we elucidated the photophysical properties of the chosen compounds and determined their suitability to be used as MOST systems. First, we

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• carboxylate (azo-H), p'-hydroxy-p-azobenzene carboxylate (azo-OH), p'-dimethylamine-p-azobenzene carboxylate (azo-NMe2), and p'-(methoxycarbonyl)azobenzene-p-oxymethylcarboxylic acid (azo-CO2Me) were synthesized (Figure 2). Their preparation and structural characterization by NMR, IR, UV–vis spectroscopy

• = |2.59| cm−1 were determined [13]. UV–vis spectroscopy All new compounds were further investigated by electronic absorption spectroscopy. The electronic absorption spectra were recorded in acetonitrile (1, 2 and 5–9) or dimethyl sulfoxide (3, 4) solution in the 190 to 1200 nm spectral range. Figure 11

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• ) was separated from the unreacted starting materials, and analyzed by UV–vis spectroscopy (Figure 3). Comparison of the UV–vis spectra of 6a and 10a/10a’ showed the successful conjugation of the DAG with the coumarin moiety [47]. Conclusion The implementation of ball milling techniques has provided the

Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials

• Widukind Moormann,
• Daniel Langbehn and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68

• were investigated by NMR and UV–vis spectroscopy and the results are listed in Table 1. Photostationary states (PSS) as well as half-lives (t1/2) were determined in acetonitrile at 300 K and 298.15 K, respectively. The (cis → trans) and (trans → cis) isomerization were achieved by irradiation into the

• ; iii) Zn, Ba(OH)2 H2O/EtOH, and CuCl2/O2, NaOH/MeOH; iv) Ti(Cl)4, DCM; v) ADMP, DBU, THF; vi) PPh3, H2O, THF; viii) TsCl, DMAP, TEA, DCM, and t-BuOK, THF. Photostationary states (300 K), absorption maxima and half-lives (298.15 K), determined by 1H NMR and UV–vis spectroscopy in acetonitrile

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• solution was purified with a syringe filter (0.45 μm) to remove the remaining fullerene solids. The gelatin/γ-CD–C60 solution was prepared by mixing gelatin/HFIP (9.4 w/v %) with γ-CD–C60/HFIP ([γ-CD] = 15 w/v %, [C60] = 1.5 × 10−2 M) at a ratio of 10:1 w/v %. The resulting solution was evaluated by UV–vis

• spectroscopy (V-730, JASCO, Japan), ESI mass spectroscopy (Autoflex III, Bruker), and small sample viscometry (m-VROCTM, RheoSense, USA). γ-CD/HFIP (15 w/v %; 500 μL) and C60/toluene (0, 0.14, 0.29, 0.43, 0.58, 0.72 mM; 25 μL) were mixed and measured by UV–vis spectrometry. The calibration curve was prepared

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• wheel moves to one of the dihydroxybenzene residues as indicated by 1H NMR and UV–vis spectroscopy. Since the axle molecule is symmetric, the wheel moves back and forward between the two dihydroxybenzene stations (green) and the rotaxane can be considered as a degenerate shuttle. Subsequently, the

• , DFT calculations, and UV–vis spectroscopy confirmed five different redox states (TTF/NDI, TTF●+/NDI, TTF2+/NDI, TTF/NDI●−, TTF/NDI2−) and shows interesting optical properties in each of these redox states making this type of mechanically constrained donor–acceptor complex very interesting for

• encircles the TTF unit instead of the dihydroxynaphthalene station in the unswitched state. As shown by 1H NMR and UV–vis spectroscopy as well as cyclic voltammetry, chemical oxidation to the TTF2+ dication triggers an expulsion of the former station and the wheel moves to the alternative

Efficient catenane synthesis by cucurbit[6]uril-mediated azide–alkyne cycloaddition

• Antony Wing Hung Ng,
• Chi-Chung Yee,
• Kai Wang and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2018, 14, 1846–1853, doi:10.3762/bjoc.14.158

• various types of building blocks. Because of the high yields of these [3]catenanes, their isolations were all straightforward. Cat-2–Cat-10 were isolated either by precipitation as the PF6− salts or by preparative HPLC, and were fully characterized by MS, NMR and UV–vis spectroscopy. Similar to Cat-1, the

London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

• Andreas H. Heindl,
• Raffael C. Wende and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

• Discussion To further investigate the prior observations, the thermal Z→E isomerization rates of azobenzenes 4–7 were determined by UV–vis spectroscopy in several solvents at 25 °C and 35 °C, respectively. The lowest thermal isomerization rates were found for the crowded 4,4’-bis[4-(3,5,5

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

• [86]. Nevertheless, the LMCT character of the prominent band I is confirmed by the calculations. The intensity of band I scales with the amount of the corresponding ferrocenium ion present and consequently the actual potential in solution can be estimated by UV–vis spectroscopy. NMR spectroscopy of

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• individually incorporated into the polymersomes and mixed together in solution; in both of the cases the final product formation was monitored by UV–vis spectroscopy. The control over the pH allowed the regulation of the enzymatic cascade (no product was observed at pH 8 in both of the reactive systems), as

Biocatalytic synthesis of the Green Note trans-2-hexenal in a continuous-flow microreactor

• Morten M. C. H. van Schie,
• Tiago Pedroso de Almeida,
• Gabriele Laudadio,
• Florian Tieves,
• Elena Fernández-Fueyo,
• Timothy Noël,
• Isabel W. C. E. Arends and
• Frank Hollmann

Beilstein J. Org. Chem. 2018, 14, 697–703, doi:10.3762/bjoc.14.58

• columns (GE Healthcare) and 10 mM sodium phosphate buffer, pH 5.5. The PeAAOx concentration was calculated based on the absorbance using the molar extinction coefficient of ε463 11,050 M−1 cm−1. Activity assay The activity of PeAAOx was determined by UV–vis spectroscopy, using an Agilent Cary 60 UV–vis

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• investigated using phenylboronic acid (3) in combination with different ortho- and para-substituted bromoarenes in aqueous ethanolic mixtures employing K2CO3 as base [38]. Monitoring of the reaction progress via inline UV–vis spectroscopy as well as offline HPLC analysis [38] led to the result that after an

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

• spectrum of complex B showed one resonance at 2.4 ppm which also demonstrated the tetra-coordination of boron [20]. UV–vis spectroscopy analysis The absorption properties of the air-stable complex B was investigated by UV–vis spectroscopy. As shown in Figure 3, there were three absorption bands at 241 nm

• greatly enhance its practicality. X-ray crystal structure analysis and UV–vis spectroscopy analysis were conducted. The tetra-coordination of the boron atoms and the highly symmetric molecular framework help to stabilize the adduct complex with respect to oxidation or hydrolysis. In addition comparative