UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation

• Tim Holtum,
• Vikas Kumar,
• Daniel Sebena,
• Jens Voskuhl and
• Sebastian Schlücker

Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240

• (GCPs). The use of UV laser excitation enables Raman binding studies of this class of supramolecular ligands at submillimolar concentrations in aqueous solution and provides a selective signal enhancement of the carboxylate binding site (CBS). A current limitation for the extension of this promising

• UVRR approach from peptides to proteins as binding partners for GCPs is the UV-excited autofluorescence from aromatic amino acids observed for laser excitation wavelengths >260 nm. These excitation wavelengths are in the electronic resonance with the GCP for achieving both a signal enhancement and the

• selectivity for monitoring the CBS, but the resulting UVRR spectrum overlaps with the UV-excited autofluorescence from the aromatic binding partners. This necessitates the use of a laser excitation <260 nm for spectrally separating the UVRR spectrum of the supramolecular ligand from the UV-excited

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• spectrofluorometer. Images were taken under a 365 nm UV lamp. DLS and zeta potential measurements were carried out using a Malvern Zetasizer NanoZS. A Horiba Jobin Yvon Fluorocube instrument fitted with a 340 nm diode laser excitation source (with a temporal resolution of 70 ps) was used for the time-resolved

Enzyme-instructed morphological transition of the supramolecular assemblies of branched peptides

• Dongsik Yang,
• Hongjian He and
• Bing Xu

Beilstein J. Org. Chem. 2020, 16, 2709–2718, doi:10.3762/bjoc.16.221

• nanofibers in the HeLa cells. Then, we used confocal laser scanning microscopy (CLSM) to examine whether these compounds deliver RPE into HeLa cells. After mixing R-phycoerythrin (RPE) [49], a red fluorescent protein, with 1 or 2 at different concentrations, we incubated the mixtures with HeLa cells for 2 h

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• -heterotetracenes and -hexacene were clearly identified, fully characterized, and their structures confirmed by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry (HRMS) via matrix-assisted laser desorption/ionization (MALDI) (Supporting Information File 1, Figures S1–S5). In the 1H NMR spectra, the

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• Instruments Co., Ltd, Shanghai, China). Mass spectra were recorded using either electrospray ionization (ESI) on a LCMS-IT-TOF instrument (Shimadzu, Kyoto, Japan) or a matrix-assisted laser desorption/ionization (MALDI) on a RapifleX MALDI Tissuetyper system (Bruker Daltonik GmbH, Bremen, Germany). Raman

Leveraging glycomics data in glycoprotein 3D structure validation with Privateer

• Haroldas Bagdonas,
• Daniel Ungar and
• Jon Agirre

Beilstein J. Org. Chem. 2020, 16, 2523–2533, doi:10.3762/bjoc.16.204

• ]. Typically, these analyses are based on mass spectrometry techniques, such as electrospray ionization mass spectrometry (ESIMS) and matrix-assisted laser desorption ionization MS (MALDIMS) [43]. Mass spectrometry techniques are best suited for the determination of the composition of monosaccharide classes

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

Tools for generating and analyzing glycan microarray data

• Akul Y. Mehta,
• Jamie Heimburg-Molinaro and
• Richard D. Cummings

Beilstein J. Org. Chem. 2020, 16, 2260–2271, doi:10.3762/bjoc.16.187

• wavelength, thus making the surface incompatible with detection reagents which rely on this wavelength. While it is possible to use nitrocellulose slides at 488 nm wavelength with lower detector sensitivity (PMT setting) and lower scan power (laser power), it might be more advisable to check other

• microarray scanner (for example, Genepix 4400A). Microarray scanners are fluorescence scanners which utilize laser technology, such that the excitation wavelength is generated by specific lasers. Commonly used laser wavelengths are 488 nm, 532 nm, 594 nm and 635 nm, which match with usual fluorophore labels

• to PMT type detectors and therefore PMT systems are preferred for more accurate measurements. In addition, newer LED-based excitation systems are being developed, but are still not as sensitive and therefore laser scanners are still used. Microarray scanners scan at pixel resolutions ranging from 2.5

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• ZetasizerNano ZS from Malvern equipped with a 4 mW He-Ne laser (633 nm wavelength) at a fixed detector angle of 173° with an avalanche photodiode detector in sodium cacodylate buffer (I = 0.05 M, pH 5.0) at 25 °C in UV-transparent microcuvettes (1 cm) equipped with a stopper. Mixtures of DNA (50 μM) and

Clustering and curation of electropherograms: an efficient method for analyzing large cohorts of capillary electrophoresis glycomic profiles for bioprocessing operations

• Ian Walsh,
• Matthew S. F. Choo,
• Sim Lyn Chiin,
• Amelia Mak,
• Shi Jie Tay,
• Pauline M. Rudd,
• Yang Yuansheng,
• Andre Choo,
• Ho Ying Swan and
• Terry Nguyen-Khuong

Beilstein J. Org. Chem. 2020, 16, 2087–2099, doi:10.3762/bjoc.16.176

• critical process parameters that control the glycosylation critical quality attributes. The advances made in protocols for capillary electrophoresis-laser-induced fluorescence (CE-LIF) measurements of antibody N-glycans have increased the potential for generating large datasets of N-glycosylation values

• description of the glycans, their relative abundance, and most importantly be high-throughput in terms of quantity, comprehensiveness, and speed of data generation. Capillary electrophoresis-laser-induced fluorescence (CE-LIF) is a glycomic analytical technology that has been adapted for automated and high

• Capillary electrophoresis of the released and APTS-labelled antibody N-glycans was performed on a CESI8000 CE instrument (Sciex) equipped with a solid state laser-induced fluorescent detector (excitation 488 nm, emission 520 nm). Separations were made across a 20 cm effective length (30 cm total length), 50

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• photons [50]. They reported a photocatalytic atom transfer radical polymerisation for the synthesis of cross-linked PMMA using the upconversion photocatalyst system and either a blue laser or a NIR (730 nm) laser. The blue laser would excite the photocatalyst component directly, whilst the NIR laser

• activated the sensitiser component, which sequentially transfers the energy to the photocatalyst to achieve the same excited state indirectly. The polymerisations were performed with a variety of light-blocking media placed between the laser source and the reaction medium. This included bacon strips to

• moulds, which could not be achieved with the blue laser [50]. Heterogeneous upconversion systems are generally crystalline nanomaterials comprising a host matrix of typically NaYF4, doped with a mixture of lanthanide ions, which act as light-absorbing sensitisers (e.g., Yb3+) and energy-combining

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• three possible dissociation pathways that can be followed (Scheme 5). Moreover, Reilly and co-workers observed the decomposition of benzaldehyde (8) into benzene (21) and carbon monoxide (22) (reaction (3) in Scheme 5) after the irradiation at 258.9 nm via laser ionization mass spectrometry and

• been studied and mentioned numerous times. More specifically, Turro and co-workers studied them with time-resolved electron spin resonance and laser flash spectroscopy. The photolysis of 8 showed that the fate of the triplet state of 8 was also dependent on the concentration of 8 and on the type of the

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• -dioxane (5 mL) under Ar at 105 °C for 30 h gave a deep orange solution (Scheme 1). Matrix assisted laser desorption/ionization (MALDI) mass spectrometry of the reaction mixture detected a single parent ion peak at m/z = 880.4687 (calcd for C54H60B4O8 = 880.4660 [M]+), making us expect its selective tetra

• many uses in organic devices. Experimental 1H NMR (500 MHz) and 13C NMR (126 MHz) spectra were recorded with a JEOL JNM-ECX500 spectrometer at 20 °C by using tetramethylsilane as an internal standard. High-resolution mass spectra (HRMS) were measured with the matrix-assisted laser desorption/ionization

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• aprotic matrix takes the function of the matrix with absorber embedded. Typically, digital imaging in Computer to Plate technology (CtP) [10][11][12][13][14], curing of liquid coatings [5][15], powder coatings [16][17], laser drying [18][19][20], laser welding [21][22][23][24][25], or laser marking of

• III. Particularly, an additional substituent at the meso-position introduces more freedoms to functionalize such materials to obtain an absorption being tailor made with respect to the light source applied. This can be a semiconductor laser [14][15][16][18][19][20] or high-power NIR-LED [65] with

• therapy named this phenomenon photothermal treatment [78][79][80] In addition, heat generation on demand also explains the function of laser drying developed for the graphic industry [11][12][13][14] or laser welding [21][22][23][24][25] where the release of heat by a photonic event responsibly patterns a

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• observed that hydroxylation of the fluoro-, chloro-, and bromobenzene derivatives provided low yields. The photocatalytic mechanism for this reaction was inspected by time-resolved transient absorption spectroscopy to detect the triplet–triplet photoredox catalyst spectrum via nanosecond laser flash

• yield the monobrominated products in excellent yields via visible-light photoredox catalysis (Scheme 20) [159]. Earlier literature reports suffered from the use of hazardous compounds (e.g., bromine) and low selectivities [160]. The reactive radical intermediates in their study were detected via laser

• bonds in the presence of photoredox catalyst 8, with a similar mechanism as shown in Figure 22, and the photocatalytic mechanism was elucidated by nanosecond laser flash photolysis (Scheme 24) [168]. Fluorine-18 is an important radioisotope used in the radiopharmaceutical industry (e.g., for drug

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

• absorption spectrum of the all trans-2 in aqueous solution (HEPES, pH 7.4, no organic co-solvent, Figure 2a) is very similar to the parent 4FAB chromophore (Figure 1). Irradiation with a 532 nm laser gave the cis PSS having the expected hypsochromically shifted n–π* band (Figure 2b, full spectra Figure S1

• , Supporting Information File 1) containing 91% of cis-2 (Figure S2, Supporting Information File 1). Irradiation of this mixture with a 405 nm laser generated the trans PSS containing 84% trans-2 (Figure S2, Supporting Information File 1). As already noted, cis-4FAB is remarkably thermodynamically stable, some

• a monofluoro-AB (1FAB) [18]. Spectra in HEPES, pH 7.4 at rt. Photochemistry of 4FABTA (2), and thermodynamic stability in physiological buffer. a) Trans–cis photochemical reaction of 2. b) Absorption spectra of all trans-2 (black), cis-2 PSS (from 532 nm laser), and trans-2 PSS (from 405 nm laser

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• cytometry staining buffer (PBS without Ca2+and Mg2+, 2.5% FBS) and stained with 5 µL of 7-AAD staining solution for 15 minutes at room temperature in the dark. Samples were acquired on a NovoCyteTM 2000 Flow Cytometry System (ACEA) equipped with a 488 nm argon laser. Detection of 7-AAD emission was

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

• . Furthermore, it has the following consequences: (i) the intensity of each line is power-dependent upon the excitation laser power, this latter point being made clear upon plotting each line intensities vs laser power in a log–log plot, (ii) the intensities of the upconversion emission lines are less and less

• cyclohexane. Photolysis experiments The description of the setup is summarized in Figure 2. The sample in a thermostated quartz cuvette was irradiated with a fibered, collimated CW 976 nm-laser beam. The transmitted laser intensity was measured using a calibrated power-meter. This measurement informed us

• ], and that the actinometer was neither sensitive to the spectrophotometer measuring beam (laser off) nor to the NIR laser beam in the absence of UCNPs (see Supporting Information File 1). Upon 976 nm irradiation, a clear-cut decrease of the absorbance in the visible range can be monitored. Typical

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• through time-of-flight matrix assisted laser desorption ionization (MALDI–TOF–MS) mass spectrometry, using sulfur as a matrix. Suzuki–Miyaura coupling to form m,p’-quaterphenyl (13) [35]: 4-Biphenylboronic acid (0.18 g, 0.91 mmol) and 1 M K2CO3 (1.5 mL) were added to a 10 mL Pyrex microwave tube. 3

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

• laser emission and the fluorescence images were acquired at 520–550 nm wavelength range. Triplicated assays could be carried out and the procedure was performed as three repetitions for each experimental condition. Plasma membrane co-staining. The cell membrane staining procedures were performed with

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

• of 0.2–0.4, reaching in some cases values as high as 0.5–0.6. Laser-flash photolysis provided evidence for the existence of excited triplet states. The dyes form fluoroboronate complexes with fluoride anions, leading to the observation of the quenching of the long-wavelength emission band and

• ratiometric response by the build-up of a hypsochromically shifted emission signal. Keywords: anions; dyes; fluorescence; laser-flash photolysis; organoboron; Introduction Boron-containing tri- and tetra-coordinated chromophores have attracted considerable interest due to their often peculiar and highly

• in some cases very close to the resolution limit of our time-correlated single-photon-counting setup. The LW emission showed considerably longer lifetimes in the 3–6 ns range. The photophysical behavior of the dyes is tentatively summarized in Scheme 4. Laser-flash photolysis The photophysical

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• + 2A]− ions were mass-selected and irradiated for 20 to 250 ms with a laser power of 95% of 25 W. At short irradiation times, the main dissociation product was [12 + Me4N − 2H]−, which is produced after elimination of two molecules of HA (HA = H+A−, Schematic presentation of dissociation in Figure S4

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

• fluorescence intensity gradually decreases during the measurement, because of the photoisomerisation process, but the use of a low laser power (0.8 µJ/pulse) and the acquisition of a large number of frames (10000) in photon counting mode allowed the characterization of the emission properties of this form. The

• source a Newport Spectra Physics Solstice-F-1K-230 V laser system, combined with a TOPAS Prime (TPR-TOPAS-F) optical parametric amplifier (pulse width: 100 fs, 1 kHz repetition rate) [35] was used, tuned at 400 nm and 350 nm for predominant excitation of the Z and E-forms of 1, respectively. To reduce

• spectrofluorometer integrated with Deltadiode-375L diode laser (λex = 373 nm, <70 ps pulse width) as the excitation source. The fluorescence decays were detected using a fast PPD-850 detector. In all cases, decays were recorded until peak counts reached 10,000. The decay traces were analyzed by the one-exponential

Excited state dynamics for visible-light sensitization of a photochromic benzil-subsituted phenoxyl-imidazolyl radical complex

• Yoichi Kobayashi,
• Yukie Mamiya,
• Katsuya Mutoh,
• Hikaru Sotome,
• Masafumi Koga,
• Hiroshi Miyasaka and
• Jiro Abe

Beilstein J. Org. Chem. 2019, 15, 2369–2379, doi:10.3762/bjoc.15.229

• difference in the photochromic properties between two isomers of Benzil-PIC, we measured the absorption spectra and nanosecond-to-microsecond transient absorption dynamics of isomer A in benzene upon repeated irradiation of 355 nm nanosecond laser pulses (355 nm, 7 mJ pulse−1, Figure S8a, Supporting

• Information File 1). The absorption band at 357 nm of isomer A gradually decreases upon irradiation of the nanosecond laser pulses and the absorption edge alternatively shifts to the longer wavelength. It indicates that the irradiation of the UV pulse induces the photochromic reactions (breaking of the C–N

• bond) and interconverts between isomer A and isomer B. The system reaches the photostationary state (PPS) within 696 shots of the laser pulses. The ratio of isomer A and isomer B is estimated to be 22:78 by the curve fitting of the absorption spectrum at the PPS with those of pure isomer A and isomer B

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

• -loaded supramolecular self-assemblies Confocal laser scanning microscopy (CLSM) was further utilized to confirm the intracellular uptake of DOX-loaded FSSAs (Figure 6). The PC-3 cells treated with DOX-loaded FSSAs indicated Hoechst 33342 blue fluorescence in their nuclei and DOX red fluorescence in their