A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• 4pzMe-F2 (left), 4pzH-F2 (middle) and 4pzMe-OMe2 (right). Experimental UV–vis spectra of 4pzMe-F2, 4pzMe-Cl2, 4pzMe-OMe2 and 4pzH-F2 in MeCN at 25 µM. Theoretical half-lives (t1/2, theor in hours and days) calculated at the PBE0-D3/6-31G** level of theory for ortho-substituted arylazopyrazoles 4pzH-X

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• length L of 9 cm, most of the light escapes the cuvette and no simplification can be done. Thus, privileging the spectral information (clear UV–vis spectra are indeed monitored) lead to a loss of information; another photoreactor design would then be necessary. Conclusion We have demonstrated that the

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

• geometry of BTD-4APTEG (implicit DMSO). (B) TD-DFT UV–vis spectra of BTD-4APTEG calculated at the PBE1PBE/6-311+G(2d,p) level of theory. Solvent effects were estimated under the IEF-PCM formalism. (C) PBE1PBE/6-311+G(2d,p)//CAM-B3LYP/6-311+G(d) HOMO and LUMO orbitals of BTD-4APTEG in DMSO involved in the

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

• Heather J. Lacey,
• Cameron L. M. Gilchrist,
• Andrew Crombie,
• John A. Kalaitzis,
• Daniel Vuong,
• Peter J. Rutledge,
• Peter Turner,
• John I. Pitt,
• Ernest Lacey,
• Yit-Heng Chooi and
• Andrew M. Piggott

Beilstein J. Org. Chem. 2019, 15, 2631–2643, doi:10.3762/bjoc.15.256

• General experimental details Optical rotations were acquired in MeOH on a Perkin-Elmer Model 341 polarimeter in a 50 × 5 mm cell or on a Jasco P-1010 polarimeter in a 100 × 3.5 mm cell. UV–vis spectra were acquired in MeCN on a Varian Cary 4000 spectrophotometer or a Jasco V-760 spectrophotometer in a 10

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• which was followed by methylation to afford 6f–h as orange solids with ≥98% trans-isomer. The synthetic strategies for the synthesis of compound 6i were reported in our previous communication [7]. In the subseries depicted in Table 3, several notable differences in both the UV–vis spectra (Figure S1

In search of visible-light photoresponsive peptide nucleic acids (PNAs) for reversible control of DNA hybridization

• Lei Zhang,
• Greta Linden and
• Olalla Vázquez

Beilstein J. Org. Chem. 2019, 15, 2500–2508, doi:10.3762/bjoc.15.243

• irradiated to obtain maximal cis (oF4Azo, 520 nm, 10 min) or trans (HTI, 405 nm, 2 min) and stored in the dark. PNA12(oF4Azo) (3) was also measured with continuous heating at 90 °C (gray squares). UV–vis spectra were collected at different time points during 10 h. Curves derived were calculate from two

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

• Eric W. Webb,
• Jonathan P. Moerdyk,
• Kyndra B. Sluiter,
• Benjamin J. Pollock,
• Amy L. Speelman,
• Eugene J. Lynch,
• William F. Polik and
• Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

• assignment. UV–vis spectra taken of eLW solutions generated by bulk electrolysis in acetonitrile and acetonitrile-d3 were compared against photoirradiated (pLW) solutions. No difference was observed in the UV–vis spectrum of the LW isomer prepared from either photolysis or electrolysis of solutions of 1b (as

Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

• Alessandro Iagatti,
• Baihao Shao,
• Alberto Credi,
• Barbara Ventura,
• Ivan Aprahamian and
• Mariangela Di Donato

Beilstein J. Org. Chem. 2019, 15, 2438–2446, doi:10.3762/bjoc.15.236

• a previously reported procedure [29]. Its UV–vis spectra were recorded on a Shimadzu UV-1800 UV–vis spectrophotometer. A Photon Technology International QuantaMaster 4 spectrofluorometer outfitted with a LPS-100 lamp power supply and Xenon arc lamp housing, ASOC-10 electronics interface, MD-4 motor

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• determined and from it the distance rAB calculated assuming rAB = rref(σref/σAB)1/6. Mass spectra were obtained on an Advion Expression-L CMS with APCI+ interface. High-resolution mass spectra were obtained on a Thermo Scientific Q-Exactive instrument in APCI positive mode. UV–vis spectra were recorded on a

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• and spectra. Upon exposure of 2b to radiation of 365 nm, changes in the UV–vis spectra proceeded slowly, due to the low absorbance of 2b in this wavelength region. However, shorter wavelengths, i.e. 254 nm, revealed fast and dramatic changes (Figure 2). After an initial decline and blue shift of the

• provided deeper insights and clarified the differential behaviour observed in the UV–vis spectra of 2b and 2f after UV irradiation. As anticipated, UV irradiation lead to E→Z isomerization of the C=C double bond in both compounds. The (Z)-isomers were found to be slightly more polar than the respective (E

• )-isomers and their absorption maxima appeared blue shifted as demonstrated by the UV–vis spectra extracted from the LC runs. Unfortunately, the amount of photoisomerization was only moderate, since after 100 minutes of continuous irradiation still substantial amounts of the (E)-isomers were present in the

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

• replacement of methoxy groups by hydroxy groups formed under ether-cleavage conditions. UV–vis spectra in MeCN: S3-(DMP)3C+ (1, red), S2-(DMP)3C+ (2, green), and S1-(DMP)3C+ (3, blue). UV–vis spectra in MeCN: S3-acridinium (4a, black) and S3-xanthenium (7, red). Inset: The 3D structure of 4a with indication

• of the principle axes of the electronic transitions. UV–vis spectra in CH2Cl2: S1-TOTA+ (9, blue line), S2-TOTA+ (8, red line), and S3-TOTA+ (6, black line). UV–vis absorption and fluorescence spectra (λex = 485 nm) of 5a in CH2Cl2 solution. Calculated molecular orbital contour plots (semi-empirical

Friedel–Crafts approach to the one-pot synthesis of methoxy-substituted thioxanthylium salts

• Kenta Tanaka,
• Yuta Tanaka,
• Mami Kishimoto,
• Yujiro Hoshino and
• Kiyoshi Honda

Beilstein J. Org. Chem. 2019, 15, 2105–2112, doi:10.3762/bjoc.15.208

• salts has been developed. The reaction of diaryl sulfides with benzoyl chlorides in the presence of TfOH smoothly proceeded to give the desired thioxanthylium salts in good yields. In their UV–vis spectra, the maximum absorption wavelengths of methoxy-functionalized thioxanthylium salts were observed at

• -withdrawing groups. Subsequently, we measured the UV–vis spectra of thioxanthylium salts. As shown in Figure 2, almost all measured UV–vis spectra are nearly identical in spite of different substituents on the benzene ring at the 9-position of the thioxanthylium core. Moreover, when the solvent effects were

• electron-withdrawing groups can be applied to the reaction. It was found that the main absorption of thioxanthylium salts around 460 nm in UV–vis spectra would be due to π–π* transitions, which was supported by DFT calculations. The present reaction provides a versatile access to functionalized

Bipolenins K–N: New sesquiterpenoids from the fungal plant pathogen Bipolaris sorokiniana

• Chin-Soon Phan,
• Hang Li,
• Simon Kessler,
• Peter S. Solomon,
• Andrew M. Piggott and
• Yit-Heng Chooi

Beilstein J. Org. Chem. 2019, 15, 2020–2028, doi:10.3762/bjoc.15.198

• coupling constants (Table 1), NOESY correlations (Figure 3) and ECD spectra (Figure 4). Bipolenin N (4) was acquired as a colourless oil. Its molecular formula was determined to be C15H28O4 from the HRESIMS [M + H − 2H2O]+ ion at m/z 237.1859 (calcd for C15H25O2+, 237.1849). The UV–vis spectra of 1–3

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• . 1H NMR spectra of β-CD-BM2-based supramolecular self-assemblies in DMSO-d6 (a), D2O (b) and DCl/D2O (c), respectively. 2D NMR NOESY spectra in D2O (a) and D2O/DCl (b), UV–vis spectra (c) and fluorescence spectra (d) of β-CD-BM2-based supramolecular self-assemblies at pH 7.4 and 5.0. Cumulative

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