New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• 14% using the complex alone. The efficiency of the combination of catalysts/H2O2 for the degradation of the studied azo dye is so confirmed and catalyst 9 is able to decompose the reaction products completely by the cleavage of the azo linkage (chromophore structure: –N=N–, responsible for the color

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• direct conjugation with the tetrathiafulvalene chromophore. The crystal packing of the arylated monopyrrolotetrathiafulvalenes is primarily defined by networks of C–H···X weak hydrogen bonds and short S···S contacts involving the tetrathiafulvalene moieties. Keywords: cyclic voltammetry; N-arylation

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• to exploit the concept of complementary multivalent binding to program the increasingly complex self-assembly of multiple different chromophore components into functional supramolecular architectures. Mono-, di-, and tetravalent axles A1, A2 and A4 and mono-, di-, and tetravalent hosts C1, C2 and C4

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• of the two different routes (to the Markovnikov or anti-Markovnikov addition products of styrene derivatives) results from the two types of photoinduced charge transfer initiated by the photoexcited catalyst (Scheme 1). If an electron-poor chromophore is applied, the first step that follows

• photocatalytic process. Back charge transfer to the photocatalyst closes the photocatalytic cycle and subsequent protonation yields the anti-Markovnikov-type addition product. In contrast, an electron-rich chromophore photoinduces an electron transfer onto the substrate. The corresponding radical anion is

• photoirradiation by both sunlight and green light-emitting diodes. Furthermore, based on Ered(PDI/PDI●−) = −0.28 V (measured by cyclic voltammetry, vs SCE, see Supporting Information File 1) and E00 = 2.35 eV (see Supporting Information File 1), PDI is an electron deficient chromophore with an excited state

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

• transfer interaction between the assembly of binding sites with F− to the chromophore [1]. With further addition of F−, intermolecular hydrogen bond formation disturbed the intramolecular hydrogen bonding and destroyed the geometrically restricted conformation [2], at the same time, the new geometrically

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• systems that have no internal chromophore. Second, the reactions illustrate how simple sustainable electrochemical methods can be employed. This is particularly important since the larger synthetic community is often hesitant to adopt electrochemical reactions. This hesitation frequently has its origins

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• charge at the heterocyclic nitrogen N-5, and strong electron affinity and polar groups at the 3 and/or 8 position of the phenanthridine can efficiently and predictably regulate the spectroscopic response (UV–vis and fluorescence) of the chromophore [48]. The understanding of the intercalation process

• be attributed to the ethidium exocyclic amines enabling by electron donation a non-radiative decay of phenanthridinium excited state, rather more likely than the previously proposed mechanism of water-induced deprotonation of phenanthridinium exocyclic amines, causing excited chromophore fluorescence

• fluorescence change in the complex with DNA, while two amino groups in 3,8-position result in a weak fluorescence with strong emission increase upon DNA binding [52][53][56]. A pronounced influence of the substituent at phenanthridine position 6 on the optical properties of the chromophore also had significant

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

• Clara Orofino-Pena,
• Diego Cortizo-Lacalle,
• Joseph Cameron,
• Muhammad T. Sajjad,
• Pavlos P. Manousiadis,
• Neil J. Findlay,
• Alexander L. Kanibolotsky,
• Dimali Amarasinghe,
• Peter J. Skabara,
• Tell Tuttle,
• Graham A. Turnbull and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2704–2714, doi:10.3762/bjoc.10.285

• lasing applications. Previously, we have designed star-shaped systems featuring energy transfer by incorporating acceptor chromophore units either within the arms [23], or in the core [24], of parent blue-emissive star-shaped oligofluorene systems. This strategy provides the ability to tune emission and

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

• Marijana Radić Stojković,
• Marko Škugor,
• Łukasz Dudek,
• Jarosław Grolik,
• Julita Eilmes and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

• affinity determination Titration of the AP series with any studied polynucleotide resulted in a pronounced decrease of the UV–vis absorbance of the DBTAA chromophore at >300 nm (Figure 1, Table 2). However, no measurable shifts of the UV–vis absorption maxima for any of the AP series were observed. In

• chromophore, whereby the ICD spectrum range >300 nm (at which DNA/RNA do not absorb) is highly informative about the orientation of the chromophore with respect to DNA/RNA chiral axis [19][20]. For instance, the intercalation of an aromatic moiety inside DNA/RNA should result in a weak negative ICD, groove

• appearance of ICD bands >300 nm upon DNA/RNA binding could be used to estimate the orientation of the DBTAA chromophore in the DNA/RNA binding site. The addition of APH, AP3, AP3am, AP5 and AP6 resulted in a decrease of the ds-DNA/RNA CD bands (range from 220 to 300 nm, Supporting Information File 1

Synthesis and optical properties of pyrrolidinyl peptide nucleic acid carrying a clicked Nile red label

• Nattawut Yotapan,
• Chayan Charoenpakdee,
• Pawinee Wathanathavorn,
• Boonsong Ditmangklo,
• Hans-Achim Wagenknecht and
• Tirayut Vilaivan

Beilstein J. Org. Chem. 2014, 10, 2166–2174, doi:10.3762/bjoc.10.224

• maxima (647 nm) compared to the single-stranded PNA (656 nm) as well as a small fluorescence increase (1.36 fold at 643 nm) (Figure 3a,b). The blue-shifted fluorescence maxima and increased quantum yields of Nile red suggest that the Nile red chromophore in complementary PNA–DNA duplexes was placed in a

• chromophore and gives rise to the observed blue shifts and the fluorescence increase. In addition, a larger increase in fluorescence was also observed with DNA targets that can form a bulge in the vicinity of the Nile red label. We propose that the Nile red label is buried within the looped out structure of

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• application in both organic chemistry and biochemistry. The reagents are generally described as “caged” compounds or photoremovable protecting groups (PPGs) in which the attached chromophore masks the biological activity of a substrate. Irradiation releases the substrate, allowing it to return to its normal

• organic chemistry and biochemistry, but they are particularly important for mechanistic studies in biochemistry and biophysics [6][8][9][10][11]. Most PPG candidates require sufficiently high energy excited states for heterolysis of a carbon–oxygen or carbon–heteroatom bond that binds the chromophore to a

• photo-Favorskii rearrangement concomitant with ligand release. The combination of these features shifts and extends the chromophore, exhibiting a more intense, broader absorption band closer to the visible region, making the PPG more accessible for photodeprotection. Thus, elaborating the two motifs by

Bis(β-lactosyl)-[60]fullerene as novel class of glycolipids useful for the detection and the decontamination of biological toxins of the Ricinus communis family

• Hirofumi Dohi,
• Takeru Kanazawa,
• Akihiro Saito,
• Keita Sato,
• Hirotaka Uzawa,
• Yasuo Seto and
• Yoshihiro Nishida

Beilstein J. Org. Chem. 2014, 10, 1504–1512, doi:10.3762/bjoc.10.155

• protein band in SDS-PAGE. The amounts were calibrated with standard samples with known concentrations. Though Bradford and Lowry methods might be useful for this kind of protein assays, the strong UV–vis absorbance of the C60 chromophore interfered with these established methodologies. Therefore, we

Homochiral BINOL-based macrocycles with π-electron-rich, electron-withdrawing or extended spacing units as receptors for C₆₀

• Marco Caricato,
• Silvia Díez González,
• Idoia Arandia Ariño and
• Dario Pasini

Beilstein J. Org. Chem. 2014, 10, 1308–1316, doi:10.3762/bjoc.10.132

• , Supporting Information File 1) show the major absorption band centered around 230 nm, typical of the binaphthyl chromophore [41]. Circular dichroism spectroscopy of the same macrocycles show the exciton couplet typical of binaphthyl moieties (Figure 3), corresponding to the maximum absorption band in the UV

• ], 3a [28], 4a [28] and p-toluenesulfonic acid 4-dimethylaminopyridinium salt (PTSA-DMAP) [45] were prepared according to literature procedures. THF (Na, benzophenone) and CH2Cl2 (CaH2) were dried before use. Analytical thin-layer chromatography was performed on silica gel, chromophore loaded, and with

Synthesis of a sucrose dimer with enone tether; a study on its functionalization

• Zbigniew Pakulski,
• Norbert Gajda,
• Magdalena Jawiczuk,
• Jadwiga Frelek,
• Piotr Cmoch and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2014, 10, 1246–1254, doi:10.3762/bjoc.10.124

• dimolybdenum methodology offers the hard proof of the absolute configuration of the vic-diols [27][28][29]. In this methodology, dimolybdenum tetraacetate acts as auxiliary chromophore allowing the application of electronic circular dichroism (ECD) to (otherwise in ECD non-observable) vic-diols. Mo2(OAc)4 when

Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery

• Jens Schmidt,
• Zeinab Khalil,
• Robert J. Capon and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2014, 10, 1228–1232, doi:10.3762/bjoc.10.121

• (2-nitropyrrole) chromophore. HPLC–HRMS–ESI(+) analysis established a molecular formula (C19H30N2NaO5, Δmmu −0.2) for this unidentified heronapyrrole, consistent with that predicted for heronapyrrole D. Although semi-preparative HPLC fractionation returned a pure sample of this new heronapyrrole, the

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

• the carbazole dyads 8e and 8f. Eventually, the absorption characteristics of phenothiazine dyads can be more easily red-shifted and, therefore, charge separation by PET should be accessible with visible light by fine-tuning the donor chromophore towards lower HOMO–LUMO gaps. Conclusion The Ugi four

First synthesis of meso-substituted pyrrolo[1,2-a]quinoxalinoporphyrins

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2014, 10, 808–813, doi:10.3762/bjoc.10.76

• demonstrated the features of both porphyrin and pyrene or fluorene subunits and suggest that there is no significant interaction between the attached chromophore and the porphyrin ring in the ground state. The fluorescence spectra of porphyrins 4f, 4g, 4h, 5 and 6 were recorded in CHCl3 at the excitation

One-pot three-component synthesis and photophysical characteristics of novel triene merocyanines

• Christian Muschelknautz,
• Robin Visse,
• Jan Nordmann and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 599–612, doi:10.3762/bjoc.10.51

• spectrometry and by combustion analysis. The appearance of only a single set of signals in the NMR spectra indicates that the process is highly stereoselective. The occurrence of deep-colored products indicates the presence of a chromophore with extended π-electron conjugation where the terminal acceptor and

• triene chromophore largely contribute to shorter wavelength absorption bands, the tosyl moiety does not display any coefficient density in the FMOs and, therefore, qualifies as a favorable electronic innocent bridge for ligating other chromophores to this novel class of merocyanines. Conclusion In

• display broad absorption bands and computations suggest, that novel types of panchromatic absorbing bichromophores should be readily available by ligating the second chromophore via the electronically nonperturbing N-sulfonyl moiety. Synthetic, photophysical, and computational studies addressing

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• driven not only by its green characteristics (i.e. using visible light), but also more importantly by its unique ability to achieve unconventional bond formation. Like most organic compounds, amines do not absorb visible light efficiently, unless they have a chromophore (e.g., conjugated π-bond systems

Self-assembly of 2,3-dihydroxycholestane steroids into supramolecular organogels as a soft template for the in-situ generation of silicate nanomaterials

• Valeria C. Edelsztein,
• Andrea S. Mac Cormack,
• Matías Ciarlantini and
• Pablo H. Di Chenna

Beilstein J. Org. Chem. 2013, 9, 1826–1836, doi:10.3762/bjoc.9.213

• to n-hexane and dichloromethane xerogels. This is indicative of a more compact assembly in this polar solvent. Due to the lack of a chromophore in 1, it was not possible to use circular dichroism to prove the helicoidal nature of the fibrillar network, but images suggest that, at least in

Zinc–gold cooperative catalysis for the direct alkynylation of benzofurans

• Yifan Li and
• Jérôme Waser

Beilstein J. Org. Chem. 2013, 9, 1763–1767, doi:10.3762/bjoc.9.204

• ) [32]. Although the yield was still moderate, this was one of the first examples of direct alkynylation of a marketed drug. It also gave access in a single step to an interesting furocoumarin derivative with an extended chromophore, which could be important for phototherapy. Mechanistically, the

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

• Sofia Telitel,
• Frédéric Dumur,
• Thomas Faury,
• Bernadette Graff,
• Mohamad-Ali Tehfe,
• Didier Gigmes,
• Jean-Pierre Fouassier and
• Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

• than the starting structure Py_1 (Figure 7, curve b). This highlights the interest of the present approach associated with the modification of the Py chromophore. CP can also be initiated in the presence of the sulfonium salt TH, e.g., with Py_3, Py_8, Py_9, Py_10 and Py_11 (Figure 6B). The conversions

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

• absorption maxima (416, 636 and 684 nm), which can be found in the violet and red color ranges. A combination of these two colors appears purple, the complementary color to green. Methacrylation of 1 does not change the chromophore and therefore the absorption maxima. The change in the absorption behavior of

• )phenylamino)anthraquinone (5). In order to introduce polymerizable functionalities, 5 was treated with methacrylic chloride to give 1,4-bis(4-((2-methacryloxyethyl)oxy)phenylamino)anthraquinone (6) (Scheme 1, step c). The obtained blue chromophore 6 shows absorption maxima at 408, 600 and 644 nm in the UV–vis

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• site, which was obtained by removal of the tetrahydropyran (THP) protecting group after coupling to the solid support. A terephthalic chromophore was incorporated into the linker to facilitate the UV detection during HPLC analysis or purification. The linker was directly attached to chloro

• -functionalized resins, which resulted in an amide bond that is stable under Zemplén conditions. Linker 1 was prepared starting from chromophore fragment 7 and masked amine 12 (Scheme 3, Supporting Information File 1). Fragment 7 was synthesized starting from aminopentanol 3 and acyl chloride 4. Following the

• in the automated solid-phase oligosaccharide synthesis. A linker that can be cleaved by hydrogenolysis and incorporates a chromophore to facilitate LC–MS analysis and purification was developed and served as example for glycosylation studies involving different solid supports. Cleavage of this linker

An improved synthesis of a fluorophosphonate–polyethylene glycol–biotin probe and its use against competitive substrates

• Hao Xu,
• Hairat Sabit,
• Gordon L. Amidon and
• H. D. Hollis Showalter

Beilstein J. Org. Chem. 2013, 9, 89–96, doi:10.3762/bjoc.9.12

• an alternative and more expeditious synthesis. This was driven by several concerns of the original route including (a) a poor overall yield, (b) challenges in the chromatographic purification of some intermediates due to their hydrophilicity and lack of a UV chromophore, and (c) generating and then

• studies. Due to the absence of a UV chromophore, the purity of FP–PEG–biotin 1 could not be determined by HPLC. TLC analysis was also problematic due to its reactivity with the highly polar solvent mixture required to move it up a plate. Nevertheless, we deem 1 to be of high purity due to the cleanliness

• group (in place of the TBS of the original synthesis) onto the PEG moiety to facilitate the early stages of the synthesis by providing a UV-active chromophore for easy detection; (b) introduction of a high yielding two-step iodination process, which avoids chromatography; and (c) reversing the sequence