p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• functional on the optimized (B3PW91/6-31G(d)) ground state geometries. It is shown, that 11 has lower excitation energies than 12 and this must be reflected in the difference between the two substituents (Cl and NO2). Although the two molecules have essentially the same basic chromophore groups when we

Two new aromatic polyketides from a sponge-derived Fusarium

• Mada Triandala Sibero,
• Tao Zhou,
• Keisuke Fukaya,
• Daisuke Urabe,
• Ocky K. Karna Radjasa,
• Agus Sabdono,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2941–2947, doi:10.3762/bjoc.15.289

• with the absorption bands at 234, 266, 313, 499, and 533 nm was closely similar to that for 1-acetyl-2,4,5,7,8-pentahydroxyanthraquinone from a fungus Geosmithia [24], suggesting the presence of a common chromophore in 1. Two highly substituted benzene rings were assembled by analysing the HMBC

Influence of the cis/trans configuration on the supramolecular aggregation of aryltriazoles

• Sara Tejera,
• Giada Caniglia,
• Rosa L. Dorta,
• Andrea Favero,
• Javier González-Platas and
• Jesús T. Vázquez

Beilstein J. Org. Chem. 2019, 15, 2881–2888, doi:10.3762/bjoc.15.282

• from 0° or 180°, since this interaction is governed by an equation with a vectorial product. The lack of exciton pairwise interactions between the two chromophores in positions 1 and 2 of each molecule could be due to the intercalation of a third chromophore between the two former in a parallel

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• groups to control a wide variety of biological process photoreversibly [8][9]. Furthermore, chemists have paid attention to spectral tuning of the AB chromophore [10][11]. Recently, an improved set of fluorine-substituted AB photochromes was developed by Hecht and co-workers [12][13]. ABs with two or

• four fluorines and electron-withdrawing groups at the para substituents all maintained the superb chemical properties of the parent tetrafluoro-(4F)AB chromophore [12]. Mild electron donation effectively destroys the beautiful separation of absorption bands of the n–π* transitions, and with it the

• in Figure 1). Our data is similar to that recently reported by Gorostiza and co-workers for a monofluorinated AB photochrome [18] (core structure shown in Figure 1 as "1FAB"). This monofluoro-(1)FAB chromophore is much less electron rich than MeO-2FAB, so it is perhaps not surprising that 2FAB cannot

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• effects of base and temperature on Michael addition–cyclocondensation sequences in the formation of α-pyrones and/or 1H-pyridines starting from diversely substituted alkynones and cyanoethylacetate. This bifurcating domino process furnishes small chromophore libraries which were characterized by

• shift to 673 nm (Table 8, entry 7). Most remarkably, the regioisomers 6c and 6e differ quite significantly with respect to their fluorescence quantum yields Φf. While chromophore 6e only emits with an efficiency of 1%, the regioisomer 6c accounts for an extraordinarily high relative quantum yield of 99

Plasma membrane imaging with a fluorescent benzothiadiazole derivative

• Pedro H. P. R. Carvalho,
• Jose R. Correa,
• Karen L. R. Paiva,
• Daniel F. S. Machado,
• Jackson D. Scholten and
• Brenno A. D. Neto

Beilstein J. Org. Chem. 2019, 15, 2644–2654, doi:10.3762/bjoc.15.257

• the BTD-4APTEG molecule, which is the net result of its electron density withdrawal character. The HOMO orbital distributes over the BTD basic scaffold and the vicinal ring but does not involve participation of the side chain of the chromophore. The electron density difference between the ground S0

• and first excited state S1 (∆ρ = ρS1 − ρS0), as shown in Figure 4D, highlights the directionality of the electron density transfer with a great deal of ICT between the cationic heterocycle and the BTD core, which stabilizes the excited state of the synthesized chromophore. These theoretical results

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• * transition bands in the wavelength range of 330–400 nm with characteristic vibronic fine structure were observed. Further, the dyes have a sharp peak at 322 nm that is assigned to the isoquinoline chromophore. The only exception is dye 18 where this peak is hidden under a strong absorption band corresponding

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• dendrimers have been designed to study this possibility. All multichromophoric compounds performed better than the model chromophore. An amplification factor of up to 2.5 per chromophoric subunit was obtained for the σ2max/εmax response (Figure 4). Interestingly, the response of the dimers increases from the

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• highest affinity of this receptor was for acetate (Ka = 1.5 × 105 M−1) and dihydrogen phosphate (Ka = 4.5 × 104 M−1). Because of the excellent properties of perylene diimide (PDI) as a chromophore, fluorophore, or redox center, this unit has become increasingly popular in the construction of

Synthesis and properties of sulfur-functionalized triarylmethylium, acridinium and triangulenium dyes

• Marco Santella,
• Eduardo Della Pia,
• Jakob Kryger Sørensen and
• Bo W. Laursen

Beilstein J. Org. Chem. 2019, 15, 2133–2141, doi:10.3762/bjoc.15.210

• chromophore, now part of the triangulenium ring system. The S0 → S1 transition in 5a is found at 507 nm, where the open form only had a very weak shoulder in its absorption spectrum (Figure 4). The ring closure of 4a into the fully planar triangulenium system 5a leads to a significant increase in the orbital

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• light range between 520 nm and 640 nm. The irradiation by visible light together with the use of an organic dye instead of a transition metal complex as photoredox catalyst improve the sustainability and make photoredox catalysis “greener”. Keywords: chromophore; dyes; electrochemistry; photochemistry

• herein the synthesis and characterization of NDI 1 as unsubstituted chromophore reference and cNDIs 2–6 as potential visible light photoredox catalysts. The cNDIs 2–6 differ by the alkyl groups at the imide nitrogens and at the nitrogens of the two core substituents at the core in order to enhance their

Tautomerism as primary signaling mechanism in metal sensing: the case of amide group

• Vera Deneva,
• Georgi Dobrikov,
• Aurelien Crochet,
• Daniela Nedeltcheva,
• Katharina M. Fromm and
• Liudmil Antonov

Beilstein J. Org. Chem. 2019, 15, 1898–1906, doi:10.3762/bjoc.15.185

• of the development of coordination chemistry [1]. Particularly chromophore ligands have been successfully utilized for colorimetric detection of the majority of metal ions as complex [2]. Some of them are used as standard tools in chelatometric titrations [3]. The design of specific ligands for

• can be seen that a hydrogen bond is formed between the nitrogen proton of one keto tautomer and the carbonyl group of another neighboring molecule. Probably, the process of associate formation is facilitated by the position of the chromophore part in the isolated K form (Figure 3, left). Obviously

Application of chiral 2-isoxazoline for the synthesis of syn-1,3-diol analogs

• Juanjuan Feng,
• Tianyu Li,
• Jiaxin Zhang and
• Peng Jiao

Beilstein J. Org. Chem. 2019, 15, 1840–1847, doi:10.3762/bjoc.15.179

• chromophore facilitating HPLC analysis. Afterwards, we tried oxidations once again. After removal of THP from 6, the resulting compound 6' was subjected to oxidation with various reagents (Scheme 4) [53][54][55]. The expected carboxylic acid or aldehyde was not observed, which further verified the intolerance

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

• due to the bulky chromophore introduced, and the resolution of the enantiomers was achieved due to the bulky size of the fluorophores. The absolute configuration of the enantiomers was determined by circular dichroism (CD) spectra. The solvent-induced aggregation behavior was investigated with the

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

• with chromophore groups on their portals. However, the changes in the absorption spectra of these receptors upon anion binding were negligible since the groups on the portals were too distant from the anion binding site in the center of macrocycle. A different approach for the preparation of UV–vis

Insertion of [1.1.1]propellane into aromatic disulfides

• Robin M. Bär,
• Gregor Heinrich,
• Martin Nieger,
• Olaf Fuhr and
• Stefan Bräse

Beilstein J. Org. Chem. 2019, 15, 1172–1180, doi:10.3762/bjoc.15.114

• can lead to improved properties, e.g., increased water-solubility of drug candidates [2] or the electronical separation of a photoswitch and a chromophore [6]. Often used moieties for these kinds of applications are triptycenes, cubanes, bicyclo[2.2.2]octanes (BCOs) and bicyclo[1.1.1]pentanes (BCPs

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

• . First of all, the azacrown nitrogen atom is linked directly to the dye and it is part of the chromophore system, responsible for the “push–pull” effect and the photophysical properties of the dye. This provides control over the “push–pull” effect in the chromophore by switching on and off states (i.e

• the vis region (Δλ = 400–600 nm) with long wavelength maxima at λmax = 520 nm indicating that their spectral properties are determined principally by the core chromophore structure. The addition of Ba2+ ions to the ACN solution of all dyes induced a decrease in the absorption maximum intensity (at

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• indicated that trifluoromethylation is an excellent tool for the detection of surface-bound materials by XPS. Keywords: chromophore; diaminoterephthalate; fluorine surface marker; fluorescence dye; lipoic acid; self-assembled monolayers; Introduction Diaminoterephthalates (DATs) are powerful fluorescence

• dyes [1][2] with outstanding properties such as high quantum yields and pronounced stability against photobleaching [3][4][5]. Although being structurally relatively simple, this class of dyes is so far underrated in the literature. The chromophore, which is accessed from succinyl succinates and

• the first title compound 3 in 71% yield. Due to the electron-withdrawing amide group, the chromophore is relatively electron deficient (absorption at 420 nm and emission at 495 nm). In order to achieve a bathochromic shift of absorption and emission bands, the DAT and ALA moieties should be

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• new caged nitroxides (nitroxide donors) 2a and 2b having the TP-responsive NPBF chromophore and the NIR TP-triggered generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical under atmospheric conditions using these species (Scheme 1). Because free radicals are cytotoxic due to their

• 2a induced cancer cell death in vitro, although no in vivo study was performed because of the low water solubility of 2a. At this point, we cannot rule out generate of ROS by photosensitization of the chromophore in the presence of O2 for the cytotoxicity. Conclusion In the present study, novel caged

• nitroxides 2a and 2b having a TP-responsive chromophore were synthesized, and OP- and TP-induced generation of the TEMPO radical with these species was examined. The quantum yields for generation of the TEMPO radical from 2a and 2b were determined to be 2.5% and 0.8% in benzene, respectively. The quantum

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

• * transitions of the trans-configured azobenzene chromophore, consistent with literature reports [24][25]. The absorptions below 310 nm (λ = 260 and 300 nm) are attributable to the π–π* transitions within the thiophenolate units of the [Cd2L]2+ fragment, which may be further differentiated as p- and α-bands of

• the parent benzene chromophore utilizing Clar’s notation [26], assuming that the electron-donating alkyl and thiol substituents exert a bathochromic effect. The spectral properties of the nickel complexes differ from those of the zinc and cadmium counterparts in that they exhibit two additional

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• by Cole-Hamilton [11]. Procedures allowing the syntheses of POSS derivatives with synthetically useful functional groups in multigram quantities have been proposed (Scheme 5). A similar procedure permits the synthesis of a series of vinylbiphenyl chromophore-decorated cubic oligosilsesquioxanes [12

• isolated yields exceeding 60%. Chromophore-functionalized silsesquioxane-core dendrimers were obtained to investigate their photophysical properties [12][14]. In the synthesized compounds chromophore properties were only slightly influenced by the core. The possibility of fine-tuning of the photophysical

• properties of the POSS-based dendritic molecule not only by changing the chromophore but also by providing tailored steric interactions between bridges and/or chromophores was proved [14]. Interestingly, the 4’-vinylbiphenyl-3,5-dicarbaldehyde group modified macromolecule (Figure 5d) displayed the ability to

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• multiple click reactions of the diazido-telechelic PBD with a dialkynyl-containing azobenzene chromophore. The newly formed triazole moieties can tune and improve the photoresponsive properties of PBD. α,ω-Functional telechelic polymers also can be synthesized by acyclic diene metathesis (ADMET

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• -dipyrromethene (BODIPY) dyes as a new class of fluorophores for the design of reporter dyes for supramolecular host–guest complex formation with cucurbit[7]uril (CB7). The BODIPYs contain a protonatable aniline nitrogen in the meso-position of the BODIPY chromophore, which was functionalized with known binding

• state of the amine lone pair with the BODIPY chromophore. In accordance with this hypothesis, a positive solvatochromism with varying contents of ACN was observed (Figure S18, Supporting Information File 1). The fluorescence quantum yields of the unprotonated BODIPY dyes were determined in 30% (v/v) ACN

• previously noted for water/DMSO mixtures [56]. The attachment of the BODIPY chromophore to the anchor groups thus reduces the binding constant by an additional factor of 10 for the aniline meso-group and by a factor of 1000 for the tetrafluoroaniline group in 4. We ascribe this to steric hindrance between

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• < OMe < NMe2) corresponds well with the strength of the donor–acceptor interplay between the electron-donating aryl substituent and the benzo[b]quinolizinium chromophore. The absorption properties depend only slightly on the solvent properties indicating that the corresponding ground state and vertical

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

• Jie Gao,
• Zhe Zheng,
• Lin Shi,
• Si-Qi Wu,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157

• molecules [9]. However, this method will greatly reduce the life of the column [10]. Moreover, the absence of a chromophore in most BPs lead to the employment of derivatization by an UV–vis light-absorbing or fluorescence label for detection [11][12]. However, directly labeling BPs in biological media is