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

• , thanks to through-space interactions. Modelling suggested that changing the relative orientation/distance of the chromophores would allow cooperative TPA enhancement to be achieved [51]. Thus, multistilbazole molecular structures of different topologies and number of dipolar chromophores, including small

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• Information File 1). When the electrolysis is performed at E1/22 + 0.15 V, the first band deriving from the π–π* transition of the NAr3•+ moiety increased in intensity (Supporting Information File 1, Figure S10), reflecting the presence of two chromophores in the generated two-electron-oxidized species 1b2

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

• efficiency was observed by Kotaskova et al. for fluorescein derivatives with one alkylthio group in the 3 position replacing an -OH/-O− group [51]. The origin of reduced fluorescence quantum yields in dyes with alkylthio donor groups in their chromophores is not clear at this point. It may result from

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• anti’-6 obtained from the reaction with diarylprolinol silyl ether (R)-18 (Table 1, entry 5) were analyzed using electronic circular dichroism spectroscopy (ECD) and TD-DFT methods. So-called in situ methodology with dimolybdenum tetraacetate (19) acting as auxiliary chromophores which proved a very

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

• solubility. In general, NDIs are electron-poor chromophores. The diamino substituents of cNDIs 2–6 are expected to increase the charge-transfer character of their photoexcited states in order to shift their absorption into the visible light and to improve their photoredox catalytic power. The photoredox

Multicomponent reactions III

• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1974–1975, doi:10.3762/bjoc.15.192

• of synthetic efficiency. Biologically and pharmaceutically relevant scaffolds are likewise tackled as chromophores, methodology development and conceptual design of macro(hetero)cycles go hand in hand with MCR-based heterocyclic chemistry. As in the previous thematic issues also this issue opens the

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

• chemical introduction of chromophores onto the rims of pillar[5]arene has been applied to allow its use as receptors for molecular sensing or biological applications [30][31][32][33]. It occurred to us that connecting fluorophores with strong absorptions in the visible range and with a high fluorescence

• quantum yield are beneficial for the application of pillar[5]arene in these fields. Perylene (Py) and 9,10-diphenylanthracene (DPA) are well known for their desirable absorption and high fluorescence quantum yield. These chromophores possess unique photophysical properties and have been widely used as

• . Aggregates with an average diameter of 531 nm are formed in 60% water (Figure S23, Supporting Information File 1) [52]. Exciton coupling CD (ECCD) signals were not observed for both compounds, even when adding more than 90% water, demonstrating that the chromophores DPA or Py units were not asymmetrically

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• ingredients [8][9][10][11], as ligands [12][13], and as chromophores [14][15][16], the partially unsaturated 2H-pyrazolines have particularly attracted attention for instance as antibacterial [17], anti-inflammatory [18], antidiabetic [19], and antidepressive [20] agents. Especially, 1-acylpyrazolines have

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

• 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

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• with their linear glycol chain counterparts, B21C7 shows great potential to be an easy-to-accessed building block to probe the non-covalent interactions and chemical transformations influenced by water molecules. Perylene diimide (PDI) and naphthalene diimide (NDI) are polycyclic aromatic chromophores

• state [93][94]. When more polar solvent MeCN or MeOH were used, merely a broad and very weak absorption band was observed. All the weak and disappearing bands indicate the overlapping of PDI chromophores to form J-type aggregates in polar solvents [84]. The intensities of the characteristic absorption

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

• ). However, in general, chromophores do not absorb at such long wavelengths and the photon energy is too low for bond-cleavage reactions to generate (i.e., uncage) functional molecules. For example, the bond-dissociation energy of the weak PhCH2–OPh, linkage is reported to be 52.1 kcal mol−1 [43]. These

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• purines and 7-deazapurines. Results and Discussion We have recently observed significant fluorescence in the triazolylpurine and triazolyl-7-deazapurine series [25][29][40][41]. Therefore, we developed synthetic methods that can provide structurally related chromophores of the purine and 7-deazapurine

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

• 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

N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes

• Fabienne Speck,
• David Rombach and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 52–59, doi:10.3762/bjoc.15.5

• processes. Conclusion One of the major current challenges in photoredox catalysis is the design of chromophores suitable for the most reductive chemical reactions, like for instance reductions by alkaline metals, affording reaction conditions that are easier to handle. While solid sodium comes up with a

Degenerative xanthate transfer to olefins under visible-light photocatalysis

• Atsushi Kaga,
• Xiangyang Wu,
• Joel Yi Jie Lim,
• Hirohito Hayashi,
• Yunpeng Lu,
• Edwin K. L. Yeow and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2018, 14, 3047–3058, doi:10.3762/bjoc.14.283

• of the iridium-based photocatalyst that triggers the radical chain process [27]. Results and Discussion Over the last decade, there has been a remarkable advance in synthetic chemistry that takes advantage of various chromophores (either metallic or organic) having visible-light charge transfer

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• described in this reference. By their broad absorptions extending from 350 to 450 nm, theses complexes are excellent candidates for photoinitiation in the visible range. Moreover, the reactivity of the chromophores can be tuned by the counter anion, PF6− being less nucleophilic than BF4−. In this context

• ][52]. Thanks to the ability of some chromophores to transfer electrons when irradiated, they can participate in catalytic processes. These later catalytic processes can be widely applied to organic synthesis or photopolymerization [17]. More than just a “metal-free” alternative, some chromophores

Microfluidic light-driven synthesis of tetracyclic molecular architectures

• Javier Mateos,
• Nicholas Meneghini,
• Marcella Bonchio,
• Nadia Marino,
• Tommaso Carofiglio,
• Xavier Companyó and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2018, 14, 2418–2424, doi:10.3762/bjoc.14.219

• different reaction partners, allowing the light-promoted construction of biologically active natural products [8]. With this aim, electron-deficient chromophores, such as 3-coumarincarboxylates D, have been used as competent reaction partners of 2-MBPs A, furnishing 3-benzylated chromanones E through a

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• process through which energy is transferred between chromophores via non-radiative dipole–dipole coupling. It is generally assumed that the non-radiative processes occur at a much slower rate than radiative processes. As such, the lifetime of S1 (τs1) is roughly equal to the lifetime of fluorescence (τf

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

• particularly suitable for the detection of analytes lacking chromophores. The key factor in IDA is the rational design of artificial receptors that are capable of binding analytes strongly and specifically. Calixarenes are the third generation of macrocyclic receptors after crown ethers and cyclodextrins. Due

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• , dehydration and aromatization reactions. The use of ionic liquids (non-volatile solvents) over toxic organic solvents makes it an environmentally benign process [45][46]. The synthesis of isomeric tetracyclic pyrazolo[3,4-b]pyridine-based coumarin chromophores 27 and 28 was reported by Chen et al. [47

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• using tCO and tCnitro [14]. Nitro groups introduce an increased charge-transfer character to chromophores, which generally results in absorption at lower energies [38][45]. Hence, tCnitro was envisioned to be able to accept the energy transferred from tC or tCO, and, thus serve as a FRET acceptor. The

• base analogue FRET pairs inside DNA When using FRET theory on fluorophores/chromophores that replace nucleobases of a normal but static DNA, estimated energy-transfer efficiencies can be simulated using the structure parameters of the B-form duplex together with photophysical parameters of the

• fluorophores/chromophores. In this way we used the photophysical parameters we already had obtained for our two FRET pairs, tCO–tCnitro and qAN1–qAnitro, to design the best combination of donor and complementary acceptor-containing DNA oligonucleotides [14][25]. We found that eight DNA strands were sufficient

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

• addition, we will discuss the newest possibilities of computational analyses of the results as an outreach from the currently used empirical rules [6] for the determination of the ligand binding mode. 2. General aspects ECD and LD are based on the phenomenon of light absorption by one or more chromophores

• chromophore also absorbs in this range, the deconvolution of all contributions is not trivial (see interpretation of results in the chapters of the corresponding methods); b) monitoring changes in polarization spectra at λ > 300 nm for ligands that have corresponding chromophores. This is the most common used

• mechanism between the various π→π* transitions of regularly arranged chromophores [14] (Figure 3, top). Chiroptical properties and ECD spectra of particular DNA or RNA sequences are therefore strongly dependent on the polynucleotide secondary structure [15], at variance to the common UV–vis spectra of the

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• L·mol−1·cm−1). All investigated dyes from the series are either not fluorescent or their fluorescence is quite low, but they become strongly fluorescent after binding to dsDNA. The influence of the substituents attached to the chromophores was investigated by combination of spectroscopic (UV–vis and

• been conjugated to a variety of molecules, including peptides [29], proteins [30], DNA [17], and DNA analogues such as peptide nucleic acid (PNA) [16][31]. TO-based chromophores assembled as a structural scaffold inside nucleic acids (TO-tethered nucleic acids) have attracted considerable attention [32

• chromophores have been studied by Armitage and co-workers [42][43]. According to these studies the fluorination of the symmetrical [42] and unsymmetrical [43] cyanine dyes results in reduced aggregation and significantly improved the photostability and photophysical properties of the dyes. The authors [43

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• chromophores [19][20][21]. This helical twist was evidenced by circular dichroism, in particular a strong bisignate Cotton effect for the DNA-templated pyrene assemblies [19][20]. Figure 1 shows selected examples of pyrene-modified nucleic acids and nucleosides. On the other hand, pyrene–nucleobase conjugates

• investigate the interactions between the compounds 2–5 when they bind specifically to a given DNA template. The titration experiments were performed with single and double-stranded oligonucleotides. The interactions between the chromophores and a 10-mer of the single-stranded oligo-2’-deoxyadenosine, (dA)10

• volume of the aliquots is small (μL range) that the DMSO concentration in the final samples never exceeded 5%. According to our previous studies, a low concentration of DMSO is tolerated by the helical DNA conformation [16]. After centrifugation, the unbound chromophores precipitated due to their