Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• properties of the monomers were investigated by NMR and UV–vis spectroscopy as well as density functional theory (DFT) calculations. Results and Discussion Synthesis Methyl linker: Synthesis of 3-(2,5-dimethoxybenzyl)-1H-pyrrole (3a) For our target compound 3-(2,5-dimethoxybenzyl)-1H-pyrrole (3a), we

• during the hydrogenation reaction, since unprotected pyrrole is known to be far less stable [25]. After desilylation by TBAF, 3-(2,5-dimethoxyphenethyl)-1H-pyrrole (3b) was obtained in a total yield of 36% over five steps from 8. Electronic properties: Evidence from NMR spectroscopy, UV–vis spectroscopy

Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time ¹³C CP-MAS solid-state NMR characterization

• Isabelle Mallard,
• Davy Baudelet,
• Franca Castiglione,
• Monica Ferro,
• Walter Panzeri,
• Enzio Ragg and
• Andrea Mele

Beilstein J. Org. Chem. 2015, 11, 2785–2794, doi:10.3762/bjoc.11.299

• aqueous phase was analyzed by UV–vis spectroscopy (Perkin-Elmer lambda 2S spectrophotometer). X-ray powder diffraction in the 2θ range of 4.7–40° (step size 0.02°; time per step 0.04 s, slits 0.6–8 mm, 30 KV × 10 mA, PSD 3) were collected on a Bruker AXS D2 Phaser diffractometer equipped with LinxEye

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• shown by UV–vis spectroscopy (Figure 2). This rate is comparable to that observed previously with the analogous complex 2, for which a photoreduction quantum yield close to unity has been determined in THF [14]. Because of such a high efficiency, the photoreduction proceeded well under direct sunlight

• (Scheme 3), precluded the use of UV–vis spectroscopy to quantitatively analyze the reductive process. For such an analysis, EPR spectroscopy was thus employed to assess the extent of copper reduction. In Figure 3, the EPR spectra of solutions of 1 (d9, S = 1/2) recorded by irradiating the samples directly

• in the probe at room temperature are presented. Control experiments conducted in THF and aqueous solutions of 1 (Figure 3a and b, respectively), confirmed the results gathered by UV–vis spectroscopy, i.e., fast reduction in THF and essentially no reduction in water. In water solution, the EPR spectra

Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2015, 11, 1434–1440, doi:10.3762/bjoc.11.155

• fluorescence spectra of these porphyrin–xanthone dyads. Keywords: 1,3-dipolar cycloaddition; fluorescence; synthesis; triazoloporphyrin-xanthone dyads; UV–vis spectroscopy; Introduction In the past few decades, porphyrin macrocycles have emerged as a unique class of heterocyclic compounds and as most

Thiazole-induced rigidification in substituted dithieno-tetrathiafulvalene: the effect of planarisation on charge transport properties

• Rupert G. D. Taylor,
• Joseph Cameron,
• Iain A. Wright,
• Neil Thomson,
• Olena Avramchenko,
• Alexander L. Kanibolotsky,
• Anto R. Inigo,
• Tell Tuttle and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1148–1154, doi:10.3762/bjoc.11.129

• and electrochemical properties of compounds 1 and 2 have been measured by UV–vis spectroscopy and cyclic voltammetry and the results compared with density functional theory (DFT) calculations to confirm the observed properties. Organic field effect transistor (OFET) devices fabricated from 1 and 2

• the synthesis of a half-unit and a final triethyl phosphite mediated homo-coupling. The resultant compounds, 1 and 2, were fully characterised and their optical and electrochemical properties elucidated via UV–vis spectroscopy and cyclic voltammetry, and explained in conjunction with DFT level

• –vis spectroscopy using dichloromethane (DCM) as the solvent (Figure 2). The obtained spectrum of compound 1 shows a maximum absorption at 380 nm and two less intense peaks at 308 nm and 274 nm. The most intensive absorption peak of 2 shows a 7 nm bathochromic shift compared to 1 and this main peak

Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

• Yuchun Ren,
• Bin Wang and
• Xiuqing Zhang

Beilstein J. Org. Chem. 2015, 11, 1089–1095, doi:10.3762/bjoc.11.122

• designed and synthesized. The molecular structures were confirmed by 1H NMR and 13C NMR spectroscopy. The rapid and reversible photoresponsive properties of the compounds were investigated by UV–vis spectroscopy. Their thermal phase behaviors were studied by DSC. The length of the spacer plays a crucial

Synthesis of carbohydrate-scaffolded thymine glycoconjugates to organize multivalency

• Anna K. Ciuk and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2015, 11, 668–674, doi:10.3762/bjoc.11.75

• photocycloaddition leading to two isomeric cis–syn- and two trans–syn-[2 + 2] photocycloaddition products. In addition, also an anti product seems to form as five (not four) H-1 signals are seen in the 1H NMR spectrum. The photocycloaddition of 7 can also be observed by UV–vis spectroscopy. Upon irradiation, the

• glycothymine branches in 13 and 14 are sterically more hindered than the thymine branches in 7 and 8. Again UV–vis spectroscopy further underlines the dimerization success as the absorption maximum at 270 nm disappears and mass spectrometry supports intramolecular photocycloaddition only (cf. Supporting

Fluoride-driven ‘turn on’ ESPT in the binding with a novel benzimidazole-based sensor

• Kai Liu,
• Xiaojun Zhao,
• Qingxiang Liu,
• Jianzhong Huo,
• Bolin Zhu and
• Shihua Diao

Beilstein J. Org. Chem. 2015, 11, 563–567, doi:10.3762/bjoc.11.61

• was 8.79 × 105 M−1, which was bigger than that obtained from UV–vis spectroscopy. This suggested the enhancement of the phenolic OH acidity by the photoexcitation [2][11][12][13][14][15]. Moreover, fluoride-dependent fluorescent intensity at 376 nm displayed an excellent linearity (R = 0.9880) in the

Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives – their stability, complexation ability in solution or when deposited on solid anionic surface

• Martin Popr,
• Sergey K. Filippov,
• Nikolai Matushkin,
• Juraj Dian and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2015, 11, 192–199, doi:10.3762/bjoc.11.20

• methods were also tested, but their usability was found to be lower than ITC. For example 1H NMR spectroscopy [34] requires relatively high concentrations of the guest and host molecules, which are often impossible to achieve due to the poor solubility in aqueous media. Conventional UV–vis spectroscopy

• extracted from cavities by MeOH (1 × 3 mL). The amount of complexed guest was quantified by UV–vis spectroscopy of the MeOH extracts against the blank sample which consisted of Nafion® 117 with no deposited PEMPDA-β-CD. This method proved to be very useful and simple tool for determination of the amount of

• surface of polymeric Nafion® 117 membrane via electrostatic interactions. Deposition kinetics and coverage of the surface were determined by ELSD. Finally, the ability of the CD derivatives bound to the solid surface to encapsulate aromatic compounds from aqueous solution was measured by UV–vis

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

• Francesco Trotta,
• Fabrizio Caldera,
• Roberta Cavalli,
• Andrea Mele,
• Carlo Punta,
• Lucio Melone,
• Franca Castiglione,
• Barbara Rossi,
• Monica Ferro,
• Vincenza Crupi,
• Domenico Majolino,
• Valentina Venuti and
• Dominique Scalarone

Beilstein J. Org. Chem. 2014, 10, 2586–2593, doi:10.3762/bjoc.10.271

• between SF and the branched β-CD polymer was further supported by UV–vis spectroscopy. The UV spectra of SF in the absence and presence of increasing amounts of polymer are shown in Figure 7. A decrease of absorbance was observed for the UV band of FS (490 nm) and an increase of absorbance of a new band

Host–guest-driven color change in water: influence of cyclodextrin on the structure of a copper complex of poly((4-hydroxy-3-(pyridin-3-yldiazenyl)phenethyl)methacrylamide-co-dimethylacrylamide)

• Nils Retzmann,
• Gero Maatz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2480–2483, doi:10.3762/bjoc.10.259

• -yldiazenyl)phenethyl)methacrylamide-co-dimethylacrylamide) and its reversible optical and complex-forming properties due to copper and cyclodextrin (CD) interactions. Color changing effects are characterized by UV–vis spectroscopy and the supramolecular behavior is investigated by dynamic light scattering

• by the addition of γ-CD [12]. Subsequent UV–vis spectroscopy allowed us to characterize the above mentioned color changes in the diluted state (Figure 2). Hereby a bathocromic shift of the peak maximum at 380 nm to 475 nm of 7 was observed due to complexation with CuSO4 which is reversible after γ-CD

End group functionalization of poly(ethylene glycol) with phenolphthalein: towards star-shaped polymers based on supramolecular interactions

• Carolin Fleischmann,
• Hendrik Wöhlk and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2263–2269, doi:10.3762/bjoc.10.235

• spectroscopy and even the naked eye. Keywords: cyclodextrin; phenolphthalein; poly(ethylene glycol); supramolecular assembly; UV–vis spectroscopy; Introduction Over the past decades, polymers with well-defined and complex architectures gained increasing attention due to a broad variety of applications

• of stable inclusion complexes was observed, representing an interesting approach towards the formation of star shaped polymers. The decolorization of a basic polymer solution caused by the complexation was of great advantage since this behavior enabled following the complex formation by UV–vis

Aryl substitution of pentacenes

• Andreas R. Waterloo,
• Anna-Chiara Sale,
• Dan Lehnherr,
• Frank Hampel and
• Rik R. Tykwinski

Beilstein J. Org. Chem. 2014, 10, 1692–1705, doi:10.3762/bjoc.10.178

• properties of the new pentacene chromophores have been analyzed by UV–vis spectroscopy (solution and thin films), thermoanalytical methods (DSC and TGA), cyclic voltammetry, as well as X-ray crystallography (for 8 derivatives). X-ray crystallography has been specifically used to study the influence of

• acetone. UV–vis spectroscopy Aryl pentacenes 3a–k have been studied by UV–vis absorption spectroscopy in CH2Cl2 solutions and as thin films cast from CH2Cl2 onto quartz. Solution-state UV–vis spectra show characteristic absorptions in the high-energy region with a maximum intensity absorption centered at

• from solid-state films. Pentacene samples 3a–k were drop-cast from a concentrated CH2Cl2 solution onto a quartz surface, and after air-drying, the absorption spectra were measured by UV–vis spectroscopy (Figure 3 and Table 1). While this method sometimes results in rather significant scattering versus

Improving the reactivity of phenylacetylene macrocycles toward topochemical polymerization by side chains modification

• Simon Rondeau-Gagné,
• Jules Roméo Néabo,
• Maxime Daigle,
• Katy Cantin and
• Jean-François Morin

Beilstein J. Org. Chem. 2014, 10, 1613–1619, doi:10.3762/bjoc.10.167

• better solubility of the PDA obtained from PAM2 compared to that obtained from PAM1, although quantitative measurements of the solubility have not been conducted because of the small quantity of materials prepared. Given the observed polymerization of diyne units, UV–vis spectroscopy was performed to

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

• Sarah Bay,
• Gamall Makhloufi,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 1006–1016, doi:10.3762/bjoc.10.100

• . These novel donor–acceptor dyads are electronically decoupled in the electronic ground state according to UV–vis spectroscopy and cyclic voltammetry. However, in the excited state the inherent donor luminescence is efficiently quenched. Previously performed femtosecond spectroscopic measurements account

• -component reaction represents a rapid and excellent modular and diversity-oriented synthesis of donor-anthraquinone dyads with various phenothiazine and carbazole model donors. Cyclic voltammetry and UV–vis spectroscopy clearly indicate an electronic decoupling of the donor and the acceptor substituents in

Molecular recognition of isomeric protonated amino acid esters monitored by ESI-mass spectrometry

• Andrea Liesenfeld and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 825–831, doi:10.3762/bjoc.10.78

• target compounds 1 and 2 in moderate yields (Scheme 2). Molecular recognition studies With our crown ether derivatives 1 and 2 in hands we studied their recognition behaviour towards the L-leucine isomers. Usually, spectroscopic techniques like NMR or UV–vis spectroscopy are used for this purpose

Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

• Jun Hu,
• Jindan Wu,
• Qian Wang and
• Yong Ju

Beilstein J. Org. Chem. 2013, 9, 2877–2885, doi:10.3762/bjoc.9.324

• and 4 (1:1, molar ratio) in DMSO/water (3:1, v/v) was studied by UV–vis spectroscopy (Figure 7a). The absorbance at 547 nm (CT absorption band) decreased with increasing temperature (35 °C to 75 °C), and the colour changed from dark red to light yellow (inset of Figure 7b), indicating the dissociation

Synthesis, characterization and luminescence studies of gold(I)–NHC amide complexes

• Adrián Gómez-Suárez,
• David J. Nelson,
• David G. Thompson,
• David B. Cordes,
• Duncan Graham,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2013, 9, 2216–2223, doi:10.3762/bjoc.9.260

• yellow. The excitation and emission maxima were then determined. These measurements were conducted on more concentrated (ca. 4 mmol/L) CH2Cl2 solutions, compared to those used for UV–vis spectroscopy. In each case, the relevant maxima could be identified. An example dataset is presented in Figure 3

Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

• Rajesh Munirathinam,
• Roberto Ricciardi,
• Richard J. M. Egberink,
• Jurriaan Huskens,
• Michael Holtkamp,
• Herbert Wormeester,
• Uwe Karst and
• Willem Verboom

Beilstein J. Org. Chem. 2013, 9, 1698–1704, doi:10.3762/bjoc.9.194

• of 13 min. A substrate concentration of 25 µM was used for all the substrates. The conversions were determined using online UV–vis spectroscopy by following the change in the extinction of a substrate specific wavelength. In case of 2-hydroxy-1-naphthaldehyde oxime (6, Table 2, entry 4) and

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• –vis spectroscopy. The analytical UV–vis peaks of p-nitrophenol and p-aminophenol are sufficiently separated both under acidic and basic conditions (Supporting Information File 1). The spectral difference between acidic and basic solutions is responsible for the association and dissociation of phenolic

• the pressure drop and plugging. The evolution of gas bubbles was observed during the reaction forming an alternate gas–liquid slug flow. GC analysis of the gas phase evidenced the evolution of CO2 as a sole product and H2 was not found. The hydrogenation reaction of p-nitrophenol was followed by UV

Synthesis, photophysical and electrochemical characterization of terpyridine-functionalized dendritic oligothiophenes and their Ru(II) complexes

• Amaresh Mishra,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2013, 9, 866–876, doi:10.3762/bjoc.9.100

• , MALDI–TOF-mass spectrometry and elemental analysis as well as by cyclic voltammetry and UV–vis spectroscopy. Electronic absorption and emission properties. One of our goals was to study electronic communication between the core metal complex and the attached oligothiophene dendron as a function of

Superstructures of fluorescent cyclodextrin via click-reaction

• Arkadius Maciollek,
• Helmut Ritter and
• Rainer Beckert

Beilstein J. Org. Chem. 2013, 9, 827–831, doi:10.3762/bjoc.9.94

• )-interactions. The supramolecular structures were characterized by 1H NMR-ROESY spectroscopy, dynamic light scattering, UV–vis spectroscopy, fluorescence spectroscopy, and asymmetric flow field-flow fractionation. By adding potassium adamantane-1-carboxylate, the thiazol dye is displaced from the CD-cavity and

• NOE interaction between protons of the methyl group of the thiazole and the triazole proton itself with CD is noticed. This indicates that only the inclusion of the pyridine moiety in the hydrophobic cavity of the CD takes place. The formation of supramolecular structures was also proven by UV–vis

• spectroscopy and fluorescence spectroscopy. Figure 2 shows the UV–vis absorption spectra of 3 in water with the characteristic band at λmax= 340 nm. The addition of a 10-fold excess of potassium adamantane-1-carboxylate, as competitive guest for CD leads to a hypsochromic shift with λmax = 336 nm, through the

End-labeled amino terminated monotelechelic glycopolymers generated by ROMP and Cu(I)-catalyzed azide–alkyne cycloaddition

• Ronald Okoth and
• Amit Basu

Beilstein J. Org. Chem. 2013, 9, 608–612, doi:10.3762/bjoc.9.66

• from the NHS ester of pyrene butyric acid 13 via intermediate 14, afforded the pyrene-end-labeled glycopolymers 16. The extent of pyrene labeling was determined by UV–vis spectroscopy and found to be essentially quantitative for the galactosyl and mannosyl polymers. The SGal polymer 12c only underwent

Polymerization of novel methacrylated anthraquinone dyes

• Christian Dollendorf,
• Susanne Katharina Kreth,
• Soo Whan Choi and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 453–459, doi:10.3762/bjoc.9.48

• of monomeric dyes out of the network was observed, as examined by UV–vis spectroscopy. This proves the covalent emplacement of the monomeric dyes in the polymer network. Figure 3 shows polymers containing 9 and 10 after sharpening for further application as iris implants. For use in medical

Synthesis and testing of the first azobenzene mannobioside as photoswitchable ligand for the bacterial lectin FimH

• Vijayanand Chandrasekaran,
• Katharina Kolbe,
• Femke Beiroth and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2013, 9, 223–233, doi:10.3762/bjoc.9.26

• . Photoirradiation was carried out in the dark at room temperature by employing a 365 nm LED. Photostationary states (PSS) were reached after 10 minutes of irradiation for both compounds. E→Z isomerisation was observed by both 1H NMR and UV–vis spectroscopy. The E/Z ratios of the ground state (GS) as well as of the