Norbornadiene-functionalized triazatriangulenium and trioxatriangulenium platforms

• Roland Löw,
• Talina Rusch,
• Tobias Moje,
• Fynn Röhricht,
• Olaf M. Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1815–1821, doi:10.3762/bjoc.15.175

• platform 2 (44%). The photophysical properties and the switching behaviour of 1, 2 and 3 were determined in solution (THF). The UV–vis spectra of the norbornadienes (NBD, black, 1a, 2a, 3a) and quadricylanes (QC, red, 1b, 2b, 3b) and the spectra of the QCs after irradiation with 311 nm for 1b and 2b or 254

• geometry coordinates and further details see Supporting Information File 1). The norbornadiene isomerizes upon irradiation with 385 nm to the quadricyclane 1b. Back-isomerization to the norbornadiene 1a is achieved upon irradiation with 311 nm or thermochemically with a half-life of 31 days. UV–vis spectra

Host–guest interactions in nor-seco-cucurbit[10]uril: novel guest-dependent molecular recognition and stereoisomerism

• Xiaodong Zhang,
• Wei Wu,
• Zhu Tao and
• Xin-Long Ni

Beilstein J. Org. Chem. 2019, 15, 1705–1711, doi:10.3762/bjoc.15.166

• ad host-2 were further studied by UV–vis spectra (Supporting Information File 1, Figure S3) and Job plot (Supporting Information File 1, Figure S4). In order to obtain detailed information on the mechanism of the complexation of G2 with host-1 and -2, 1H NMR titration experiments in acidic aqueous

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

• ). These results demonstrated that the bulky substituents DPA or perylene effectively prevent the ring rotations, and therefore making the separation of Rp and Sp conformers possible. Figure 3d and e show the circular dichroism (CD) and UV–vis spectra of each fraction for P5A-DPA. The CD signals of both

• DPA is responsible for the red-shift of the absorption. For P5A-Py, however, adding water to the THF solution led to a continuous red-shifting of the UV–vis spectra and increasing of CD signal, which is reasonable, as the planar structure of Py tends more to get aggregated in water by π–π stacking

• ) apparatus. UV–vis spectra were obtained on a JASCO v-650 spectrometer. Fluorescence spectra and fluorescence lifetime decay measurements were recorded on a HORIBA FluoroMax–4 (TCSPC) spectrofluorimeter. Circular dichroism spectra were measured on a JASCO J-1500 spectrometer using a quartz cuvette of 1 cm

Diazocine-functionalized TATA platforms

• Roland Löw,
• Talina Rusch,
• Fynn Röhricht,
• Olaf Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1485–1490, doi:10.3762/bjoc.15.150

• ). The UV–vis spectra of 1 and 2 are shown before and after irradiation with 405 nm and 525 nm. Both diazocine-TATAs 1 and 2 exhibit similar UV spectra. The n→π* transition of cis-1 appears at 403 nm and at 494 nm in the trans-isomer. The corresponding absorption maxima in diazocine-TATA 2 are 409 nm

• -diazocines (1b, 2b) and with 525 nm or thermally back to the cis-diazocines (1a, 2a). UV–vis spectra of 1 (left) and 2 (right) in THF at room temperature. Black: as synthesized, red: after irradiation with 405 nm, and blue: after irradiation with 525 nm. STM images (30 × 30 nm², Ubias = 0.3 V, It = 40 pA) of

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• the silyl ethers. Unlike in the solution reaction, the HEBM isolated reaction products of β-CD were almost completely insoluble in water, while the γ-CD derivative was somehow soluble or solubilised, as seen in the UV–vis spectra. Both the β- and γ-CD derivatives showed high complexation affinity

• with the front, and they were found to be very poorly charrable. While it is not clear whether the product itself was dissolved or whether the particle size was smaller than <0.22 µm, the UV–vis spectra clearly show the hypsochromic shift that was caused by complexation with increasing amounts of added

• (Table 3, entry 9) and γ-CDP (Table 3, entry 12) prepared in a ball mill on 2 mmol scale. Normalised particle-size distribution of insoluble CD polymers (entries 9, 10, and 12 of Table 3). UV–vis spectra and adsorption isotherm of the insoluble β-CDP polymer in 10 ml 0.050 mM MO solution (entry 10 of

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

• by changes of the ionic strength. Shortly after the addition of dAAP to the AuNR solution, UV–vis spectra were recorded (Figure 2a) indicating a strong LSPR shift of λ = 36 nm to λ = 757 nm while the TSPR band change is negligible. This indicates selective end-to-end assembly, whereas side-to-side or

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• measured in HEPES buffer (10 mM, pH 7.4) at 25 °C. Instruments Steady-state fluorescence measurements were recorded in a conventional quartz cuvette (light path 10 mm) on a Cary Eclipse equipped with a Cary single-cuvette peltier accessory. UV–vis spectra were recorded in a quartz cuvette (light path 10 mm

Selective detection of DABCO using a supramolecular interconversion as fluorescence reporter

• Indrajit Paul,
• Debabrata Samanta,
• Sudhakar Gaikwad and
• Michael Schmittel

Beilstein J. Org. Chem. 2019, 15, 1371–1378, doi:10.3762/bjoc.15.137

• were established through 1H NMR (Figure 4) and UV–vis spectra (Figure 3b). DFT (B3LYP/6-31G(d)) calculations on rectangle 5 and sandwich complex 6 allow the modeling of the supramolecular architecture and provide some structural insights. The DFT computations demonstrate that the sandwich complex is

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

• cation. Also, FeBr3, a chiral Fe(III) monophosphate (M = FeBr2) 1c or even the bulky Fe(III) bisphosphate 2a promoted the dissociation of trityl bromide. In the latter case, the dissociation was estimated to be 54% by in-situ IR spectroscopy (UV–vis spectra were not applicable due to absorption overlap

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• –vis absorption peak at 295 nm. As expected, the UV–vis spectra of CCDs show two absorption peaks, one at 295 nm and the other at 340 nm, indicating that CP[5] has been linked on the surface of C-dots. The Fourier transform infrared spectra (FTIR) of C-dots, CN-dots, and CP[5] are shown in Figure 1d

• Fe3+ ions with high selectivity. TEM images of a) CCDs and b) CN-dots. c) UV–vis spectra of CP5, CN-dots, and CCDs. d) FTIR spectra of CP5, CN-dots, and CCDs. e) PXRD patterns of CP5, CN-dots, and CCDs. f) TGA curves of CN-dots and CCDs. a) Photographs of CN-dots and CCDs in aqueous media in natural

• fluorescence intensity versus the concentrations of Fe3+ ions. Experimental conditions: Slit widths: Ex. 5 nm, Em. 5 nm; λex = 340 nm. e) Spectral overlap of the UV–vis absorption spectrum of Fe3+ (red line) and fluorescence spectrum of CCDs (black line). f) UV–vis spectra of CCDs, Fe3+, and CCDs after the

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

• are given in Supporting Information File 1. 4-(Aza-15-crown-5)benzocarbaldehyde (3) was synthesized using a slightly modified procedure [16][17]. UV–vis spectra were measured on a Unicam 530 UV–vis spectrophotometer in conventional quartz cells of 1 cm path length. The spectral bandwidth and the scan

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

• spectrometer equipped with a diamond ATR unit. UV–vis spectra were recorded with a Shimadzu UV-1800, fluorescence spectra with a Shimadzu RF-5301PC spectrometer. Compounds 1 [41] and 5 [44] were prepared according to literature procedures. All other starting materials were commercially available. XPS of SAMs

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

• using CDCl3. IR spectra were recorded with a FTIR spectrometer. UV–vis spectra were taken by a SHIMADZU UV-3600 Plus spectrophotometer. Mass spectra were measured by a Mass Spectrometric Thermo Fisher Scientific LTQ Orbitrap XL, performed by the Natural Science Center for Basic Research and Development

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

• chamber of a UV–vis spectrometer. Figure 13 shows the corresponding UV–vis spectra, which were recorded directly after sample preparation. As can be seen, the intensity of the π→π* band at 325 nm for the trans-azobenzene carboxylate decreases with increasing irradiation time, while the intensity of the n

• Tensor 27 FTIR spectrometer. UV–vis spectra were recorded on a Jasco V-670 UV–vis/near-IR spectrophotometer. Elemental analyses were carried out with a Vario EL – elemental analyzer. NMR spectra were recorded on a Bruker Fourier 300 spectrometer or Avance DRX 400 at 298 K. 1H and 13C chemical shifts

• ) and 1.0 T (4). The solid lines represent the best theoretical fit to Equation 1 (see text). Experimental and calculated values are provided as Supporting Information File 1. UV–vis spectra of Hazo-H (red line), [Cd2L(μ-Cl)](ClO4) (black line) and [Cd2L(μ-azo-H)]ClO4 (1, blue line) in acetonitrile

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

• level. Biologically relevant molecules made, used or derivatized by mechanochemistry. Isomeric diacyl-sn-glycerols (DAGs). UV−vis spectra of DAG 6a (dotted line) and conjugated DAGs 10a and 10a’ as a mixture (10a/10a’ 72:28) in toluene at a concentration of 0.5 μM. Synthetic route to access protected

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• Uniwise International Co., Ltd., 99% pure) was purified from stabilizers by distillation under reduced pressure (≈6,6 kPa). All operations with monomer and catalyst were carried out in a glove box MBraun Labstar provided with an argon atmosphere. UV–vis spectra of catalyst system solutions were registered

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

• mechanoresponsive polymers such as polyurethanes, polyesters, polyamides, polyureas and polyolefines. (a) Isomerization of parent diazocine 1. Distances of carbon atoms para to the ethylene bridge were determined at the B3LYP/6-31g* level of DFT [23]. (b) UV–vis spectra of parent diazocine 1 (left), 3,3

• ’-diaminodiazocine 2 (center) and 4,4’-diaminodiazocine 3 (right). Continuous lines: 100% cis and dashed lines: PSS (385 nm) at 298.15 K in acetonitrile. Synthesized target diazocines 4–7 for applications in responsive materials. UV–vis spectra of 3,3’-diaminodiazocine 2 (left), 3,3’-di(aminomethyl)diazocine 6a

• . Supporting Information Supporting Information File 346: Analytical equipment, experimental procedures, NMR and UV–vis spectra. Acknowledgements The authors gratefully acknowledge financial support by the Deutsche Forschungsgesellschaft (DFG) within the Sonderforschungsbereich 677, “Function by Switching”.

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• according to the procedures reported in literature. Instrumentation. UV–vis spectra were recorded on a Beckmann Coulter DU 800 spectrophotometer, equipped with a Peltier thermostatic apparatus. FTIR spectra on powders were acquired on a Bruker VERTEX70 instrumentation. NMR spectra were recorded on a Bruker

Silanediol versus chlorosilanol: hydrolyses and hydrogen-bonding catalyses with fenchole-based silanes

• Falco Fox,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2019, 15, 167–186, doi:10.3762/bjoc.15.17

• otherwise specified. NMR spectra were recorded on a Bruker Avance II 300 instrument. UV–vis spectra were recorded by using a Perkin Elmer Lambda35 spectrometer. The samples were placed in quartz cells of 1 cm path length. NMR spectra, UV–vis spectra, crystal data and the coordinates of computed stationary

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• ] scale. UV–vis spectra were measured on a Lambda 18 instrument from Perkin Elmer and fluorescence spectra were measured on a LS50B instrument from Perkin Elmer. All EI spectra were measured on a MAT 95 XL instrument from Thermo Finnigan and ESI spectra of synthesized compounds were measured with either

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• different analytical methods [56]. Structural integrity of the β-barrel fold was confirmed by CD spectroscopy. ICP–OES was used to determine the metal content. A little less than one metal center per protein molecule was found to be present. Additional absorption bands in the UV–vis spectra around λ = 380

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• nπ* absorption maxima are in a range between 508 nm to 516 nm (for UV–vis spectra measured in acetone see Supporting Information File 1). The half-lives vary from 24.8 h to 6.7 d. For the carboxylic acid functionalized S-diazocine 4 the two isomers generated after irradiation with 405 nm could be

• separated by chromatography and the UV–vis spectra of the pure cis and trans isomers could be measured in an acetonitrile/water mixture. Figure 2 shows the UV spectra of the pure cis and trans isomers of 4. The nπ* band of the cis isomer displays an absorption maxima at λmax = 392 nm. Upon irradiation with

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• under 355 nm irradiation, a broad transient absorption from 300 nm to 390 nm that did not decline over the measurement time (up to 10 µs, see Supporting Information File 1). In the UV–vis spectra recorded after the LFP experiment a significant change in absorption in the 300–370 nm region was observed

Bioinspired cobalt cubanes with tunable redox potentials for photocatalytic water oxidation and CO₂ reduction

• Zhishan Luo,
• Yidong Hou,
• Jinshui Zhang,
• Sibo Wang and
• Xinchen Wang

Beilstein J. Org. Chem. 2018, 14, 2331–2339, doi:10.3762/bjoc.14.208

• properties of the 1-R complexes, UV–vis absorption measurements were conducted. As shown in Figure 2, three absorption bands are observed in the UV–vis spectra. The lowest energy absorption appearing as a shoulder at 645 to 660 nm, is associated with the d–d transitions involving 1A1 → 1T1 and 1A1 → 1T2 for

Coordination-driven self-assembly of discrete Ru₆–Pt₆ prismatic cages

• Aderonke Ajibola Adeyemo and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2018, 14, 2242–2249, doi:10.3762/bjoc.14.199

• form a single framework architecture through a one-pot self-assembly strategy. 1H NMR of 3b in CD3OD. UV–vis spectra of the metalloligand 2 and heterometallic prismatic cages 3a and 3b in methanol (1.0 × 10−5 M) at 298 K. ESIMS spectrum of 3a in methanol. Inset: experimentally observed isotopic