Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• at ca. 390 nm (a and b) are Raman bands of the solvent. Fatigue resistances of compounds SyOTh1 (A and B) and SyTh1 (C). Parts A and C show the absorbance at certain wavelengths after cyclization (top values) and cycloreversion (bottom values). Part B shows the change in absorbance at 478 nm for each

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• studied by in situ Raman and ex situ IR spectroscopy. Keywords: ball milling; Friedel–Crafts reaction; mechanochemistry; Introduction The Friedel–Crafts reaction (FCR) is a very powerful tool in organic chemistry for the synthesis of aromatic ketones. It is of great industrial importance and widely used

• demonstrate that quinones could be prepared by simple one-pot FC protocols in the case of reactive aromatics. In situ Raman spectroscopy [60] was applied to study mechanistic aspects of the solid state reaction of phthalic anhydride with p-xylene. Raman spectra were simulated and positions of signals for

• transient reactive intermediates were predicted by density functional theory method B3LYP/6-31G* (Supporting Information File 1) [61]. The stretching of the +C≡O bond of the acylium ion was predicted to be at about 2300 cm−1. Raman spectroscopy revealed that the complexation of phthalic anhydride with AlCl3

Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation

• Sebastian Haferkamp,
• Andrea Paul,
• Adam A. L. Michalchuk and
• Franziska Emmerling

Beilstein J. Org. Chem. 2019, 15, 1141–1148, doi:10.3762/bjoc.15.110

• triclinic product. Inclusion of catalyst in the final product, as evidenced by mass spectrometric analysis, suggests this complex polymorphic pathway may be due to seeding effects. Multivariate analysis for the in situ Raman spectra supports this complex formation pathway, and offers a new approach to

• reaction environment. It was subsequently demonstrated how a combination of different in situ methods can provide more thorough investigation of mechanochemical reaction mechanisms [14][15][16]. Of particular benefit to synthetic reactions, such as C–C bond formation [17][18], the use of Raman spectroscopy

• is of great interest. The characteristic bands are usually well separated, and the course of the reaction can be followed easily. The advantage of Raman spectroscopy was recently demonstrated [19], where its combination with XRPD allowed monitoring of the mechanochemically catalyzed Knoevenagel

DABCO- and DBU-promoted one-pot reaction of N-sulfonyl ketimines with Morita–Baylis–Hillman carbonates: a sequential approach to (2-hydroxyaryl)nicotinate derivatives

• Soumitra Guin,
• Raman Gupta,
• Debashis Majee and
• Sampak Samanta

Beilstein J. Org. Chem. 2018, 14, 2771–2778, doi:10.3762/bjoc.14.254

• Soumitra Guin Raman Gupta Debashis Majee Sampak Samanta Discipline of Chemistry, Indian Institute of Technology Indore, Simrol, Indore, 453552, Madhya Pradesh, India 10.3762/bjoc.14.254 Abstract An intriguing DABCO-catalyzed and DBU-promoted one-pot synthesis of an important class of (2

Synergistic electrodeposition of bilayer films and analysis by Raman spectroscopy

• Saadeldin E. T. Elmasly,
• Luca Guerrini,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Neil J. Findlay,
• Karen Faulds and
• Peter J. Skabara

Beilstein J. Org. Chem. 2018, 14, 2186–2189, doi:10.3762/bjoc.14.191

• successfully demonstrated. Moreover, careful control of the electrochemical conditions allows the degree of doping to be effectively altered for one of the polymer layers. Raman spectroscopy confirmed the formation and doped states of the PEDOT/PEDTT bilayer. The electrochemical deposition of a bilayer

• ) raises the possibility of depositing a subsequent layer via solution-processing. Keywords: bilayer; electropolymerisation; PEDOT; PEDTT; Raman; Findings Fabrication of multilayer organic electronic devices has been extensively researched in the past 20 years, resulting in numerous processes and

• PEDOT layer remains predominantly doped. In order to support the formation of a PEDOT/PEDTT bilayer using this technique and to clarify the nature of doping in the two layers, freshly fabricated bilayers (using 10−4 M monomer solution) were grown on ITO and analysed by Raman spectroscopy, alongside

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• the reaction and generation of highly luminescent compounds which hindered in situ monitoring by Raman spectroscopy. However, in situ monitoring of the milling processes was enabled by using Cu(0) catalysts in the form of brass milling media which offered a direct insight into the reaction pathway of

• spin resonance (ESR) spectroscopy; in situ Raman monitoring; mechanochemistry; quinoline; solid-state click chemistry; Introduction The copper-catalyzed azide–alkyne cycloaddition (CuAAC) represents a prime example of click chemistry. Click chemistry describes “a set of near-perfect” reactions [1] for

• states for the mechanochemical CuAAC reaction of target quinoline derivatives and p-substituted phenyl azides. We have also investigated the effect of the p-substituent in the azide on the reaction progress and yields. Direct monitoring by in situ Raman spectroscopy was used to gain an insight into the

Structural diversity in the host–guest complexes of the antifolate pemetrexed with native cyclodextrins: gas phase, solution and solid state studies

• Magdalena Ceborska,
• Magdalena Zimnicka,
• Aneta Aniela Kowalska,
• Kajetan Dąbrowa and
• Barbara Repeć

Beilstein J. Org. Chem. 2017, 13, 2252–2263, doi:10.3762/bjoc.13.222

• equivalent – methyl α-D-glucopyranoside – was investigated for a deeper understanding of the type of host–guest interactions. Solid state studies of PTX/CDs were performed using FTIR–ATR and Raman spectroscopy techniques. Keywords: antifolate; cyclodextrin; hydrophobic interactions; inclusion complexes

• ; pemetrexed; supramolecular chemistry; Introduction Herein, supramolecular host–guest complexes of the potent folic acid inhibitor pemetrexed (PTX, Figure 1a) with native cyclodextrins (α-, β- and γ-CDs, Figure 1b) in the gas phase (MS), in solution (NMR, UV–vis) and in the solid state (Raman, FTIR–ATR) were

• methods – FTIR–ATR and Raman were used for describing the way of PTX-CD interactions. The IR spectroscopy in the region characteristic for δ-HOH bending of water molecules attached to CDs (1600–1700 cm−1) is usually employed for tracking of the inclusion complex formation, however, Raman spectra of this

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

• Patrick A. Julien,
• Ivani Malvestiti and
• Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

• milling frequency on the course of a mechanochemical organic reaction conducted using a vibratory shaker (mixer) ball mill. The use of in situ Raman spectroscopy for real-time monitoring of the mechanochemical synthesis of a 2,3-diphenylquinoxaline derivative revealed a pronounced dependence of chemical

• : green chemistry; mechanism; mechanochemistry; milling; monitoring; Raman spectroscopy; Introduction Over the past decade, mechanochemical reactions [1][2][3][4], i.e., chemical transformations induced or sustained through the application of mechanical force in the form of grinding, milling and shearing

• mechanochemical reactions. A significant recent advance in mechanistic studies of mechanochemical reaction mechanisms was the introduction of techniques for in situ, real-time monitoring of ball milling processes [27], first through synchrotron X-ray powder diffraction (XRPD) [28][29], and later by Raman

Solid-state studies and antioxidant properties of the γ-cyclodextrin·fisetin inclusion compound

• Joana M. Pais,
• Maria João Barroca,
• Maria Paula M. Marques,
• Filipe A. Almeida Paz and
• Susana S. Braga

Beilstein J. Org. Chem. 2017, 13, 2138–2145, doi:10.3762/bjoc.13.212

• using elemental analysis, powder X-ray diffraction (PXRD), Raman, infrared and 13C{1H} CP-MAS NMR spectroscopies, and thermal analysis (TGA) to verify fisetin inclusion and to present a hypothetical structural arrangement for the host–guest units. The antioxidant activity of the γ-CD·fisetin inclusion

Mechanochemical Knoevenagel condensation investigated in situ

• Sebastian Haferkamp,
• Franziska Fischer,
• Werner Kraus and
• Franziska Emmerling

Beilstein J. Org. Chem. 2017, 13, 2010–2014, doi:10.3762/bjoc.13.197

• .13.197 Abstract The mechanochemical Knoevenagel condensation of malononitrile with p-nitrobenzaldehyde was studied in situ using a tandem approach. X-ray diffraction and Raman spectroscopy were combined to yield time-resolved information on the milling process. Under solvent-free conditions, the reaction

• combined X-ray diffraction and Raman spectroscopy measurements in a tandem approach. Our investigations reveal that the formation of the crystalline product begins after 36 min and is completed after 50 min. The reaction can be described as a melt-mediated reaction since malononitrile melts during the

• of the reactants reveal a complete and quantitative reaction (see Figure 1). For the in situ investigations, time-resolved X-ray diffraction patterns and Raman spectra were recorded during the milling reaction. The Raman laser and the X-ray beam were focused on the same spot at the inner wall of a

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• Raman spectroscopy was devised [27]. Finally, these two in situ techniques have been successfully merged to allow simultaneous monitoring of mechanochemical reactions by PXRD and Raman spectroscopy [28][29]. Review Mechanochemical synthesis of (thio)ureas Thioureas In a paper by Kaupp et al. a study on

• nucleophilic aromatic substrates with bis(1-benzotriazolyl)methanethione (26) under ball-milling conditions (Scheme 9) [41]. The application of in situ Raman spectroscopy monitoring of mechanochemical reactions, in combination with solid-state characterization through FTIR-ATR, PXRD and ssNMR analyses

• almost quantitative yields. The in situ Raman monitoring of a 1:2 mixture of 26 and 4-bromoaniline, which results in the formation of symmetrical bis(4-bromophenyl)thiourea 28d revealed thiocarbamoyl benzotriazole 27d as the reactive intermediate (Figure 4). Starting from 27a or 29, bis-thiourea 22a can

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• times for the same reaction examined consecutively without any significant drop in catalytic activity. Figure 1 shows the results of consecutive recycle runs. Characterization of the recovered catalyst To establish the reaction mechanism, we characterized the recovered catalyst by Raman, XRD, XPS and

• TEM studies. The Raman and XRD results of fresh Ni/RGO-40 were reported in our previous publication [48]. However, for comparison, Raman and XRD of a fresh Ni/RGO-40 sample were again recorded and presented along with that of the recovered sample. The Raman spectrum of the Ni/RGO-40 composite (Figure

•  2a) exhibits a characteristic D band at 1344 cm−1 (A1g vibrations of six-membered sp2 carbon rings) and the G band at 1580 cm−1 (first-order scattering of the E2g mode of sp2 domains). After the first run, the Raman spectrum of the recovered Ni/RGO-40 catalyst (Figure 2b), however, did not reveal any

Theoretical simulation of the infrared signature of mechanically stressed polymer solids

• Matthew S. Sammon,
• Milan Ončák and
• Martin K. Beyer

Beilstein J. Org. Chem. 2017, 13, 1710–1716, doi:10.3762/bjoc.13.165

• potential energy surface, closely resembling FMPES. With EFEI, standard quantum chemical tasks like geometry optimization, reaction path following [54][56][68] and frequency calculations can be performed with minor modifications of standard packages. UV–vis, Raman and IR spectra of small model molecules

Block copolymers from ionic liquids for the preparation of thin carbonaceous shells

• Sadaf Hanif,
• Bernd Oschmann,
• Dmitri Spetter,
• Muhammad Nawaz Tahir,
• Wolfgang Tremel and
• Rudolf Zentel

Beilstein J. Org. Chem. 2017, 13, 1693–1701, doi:10.3762/bjoc.13.163

• Raman spectroscopy revealing typical carbonaceous bands, such as the G-band at 1584 cm−1 and the D-band at 1355 cm−1, which is shown in Figure 4c. Furthermore, the residual carbonaceous content was determined by TGA, where the weight loss decreases from 20% (for the block copolymer coated particles) to

• lattices which might also help to provide longer paths for electrons to travel within the electrode. Summarizing, the Raman spectrum, the TGA measurements and the TEM images proves the success of the formation of a thin coating around the TiO2 particles. Currently, we are investigating the application of

• simultaneously introducing an anchor group. Afterwards, we showed the successful in situ synthesis of TiO2 particles with the block copolymer as a ligand on the surface. Raman spectroscopy and TEM images show that PILs are suitable carbon precursors and the herein introduced materials can be further applied as

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• translucent milling vessels made of poly(methyl methacrylate) (PMMA) with powder X-ray diffraction (PXRD) [6][7], Raman spectroscopy [8], or a combination of both techniques [9]. On the other hand, attempts to combine photo- and mechanical activation to favor chemical processes have been mainly explored in

Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

• Qing Yin,
• Qi Chen,
• Li-Can Lu and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 1212–1221, doi:10.3762/bjoc.13.120

• functionalization of the materials. Silver nanoparticles (AgNPs) have received extensive attention because of their unique properties and applications in catalysis [18], antibacterial use [19], phase separation [20], surface-enhanced Raman scattering (SERS) [21], etc. Compared with bulk silver, AgNPs have a more

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• because they can be employed to enhance the intensity of Raman signals close to the NP surface, widely explored in biomedical diagnostics (surface enhanced Raman spectroscopy, SERS). This effect is even more intense when the nanoparticles possess an irregular shape, generating an anisotropic distribution

• efforts, the GAuNPs showed an incremented lectin identification power, at low protein concentrations, enabling an easy tool for sugar–lectin recognition. The glycan–protein interaction has been studied as well employing surface-enhanced Raman spectroscopy (SERS) exploiting AuNP ability in amplifying Raman

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• (like UV, IR or Raman spectroscopy) which may be coupled with the reactor jacket flow rate to maintain the desired conversion. The azide and amide streams can be mixed and preheated at 110 °C. The preheated stream can then flow through a copper tubing reactor or a packed bed reactor with copper packings

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• ). In the absence of KH2PO4, irregular black carbon aggregates were obtained. Raman and TEM analysis showed both types of FCDs had graphitic crystallinity. This example highlights that an inorganic-based dehydrating agent could be used instead of a traditional diamine SPA to induce CD dehydration and

• burst of nucleation takes place and the carbon nuclei grow to partially nanocrystalline CDs with certain hydrophilic functional groups in the surface. Raman, FTIR and XPS data confirmed the presence of aromatic amines, hydroxy and carboxy groups on the CD surface. Subsequently, Liu et al. reported the

• reported syntheses afford CDs with sp2 crystalline or amorphous cores, the team showed that the resultant nanoparticles had an sp3 nanocrystalline core, as determined by HRTEM and Raman spectroscopy. The authors attributed this observation to the relatively mild conditions used. They also showed that the

NMR reaction monitoring in flow synthesis

• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

• the production scale for quality control, the coupling of flow and microreactor technology with a good analytical method is a prerequisite. Several analytical methods have been used and these include fluorescence, ultraviolet–visible (UV–vis), RAMAN, infrared (IR) and nuclear magnetic resonance (NMR

Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

• Monica Ferro,
• Franca Castiglione,
• Nadia Pastori,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2017, 13, 182–194, doi:10.3762/bjoc.13.21

• condensation reaction of the OH groups of the glucopyranose units of cyclodextrins (CD) with a poly-functional cross-linking agent [3]. CDNS have been characterized, in the solid state, by a repertoire of physical methods such as solid-state 13C CP-MAS NMR, FTIR and Raman spectroscopy [4][5][6]. Moreover, in

A postsynthetically 2’-“clickable” uridine with arabino configuration and its application for fluorescent labeling and imaging of DNA

• Heidi-Kristin Walter,
• Bettina Olshausen,
• Ute Schepers and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2017, 13, 127–137, doi:10.3762/bjoc.13.16

• with a Varian Cary 100 spectrometer equipped with a 6 × 6 cell changer unit at 20 °C. Fluorescence was measured with a Jobin–Yvon Fluoromax 3 fluorimeter with a step width of 1 nm and an integration time of 0.2 s. All spectra were recorded at 20 °C and are corrected for Raman emission from the buffer

Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties

• Pierre Boufflet,
• Sebastian Wood,
• Jessica Wade,
• Zhuping Fei,
• Ji-Seon Kim and
• Martin Heeney

Beilstein J. Org. Chem. 2016, 12, 2150–2163, doi:10.3762/bjoc.12.205

• block copolymer case, non-fluorinated segments appear to slightly frustrate the aggregation of the more fluorinated block. However, in situ temperature dependent Raman spectroscopy shows that the intramolecular order is more thermally stable in the block copolymer than in the corresponding blend

• , suggesting that such materials may be interesting for enhanced thermal stability of organic photovoltaic active layers based on similar systems. Keywords: conjugated block-copolymer synthesis; fluorination; microphase stabilization; polythiophene; temperature-dependent Raman spectroscopy; Introduction With

• polymers’ UV–visible absorption and Raman scattering spectra are compared with those of the corresponding blends of P3OT and F-P3OT, as well as the homopolymers. The results of this study suggest that the tethering of P3OT and F-P3OT blocks may not lead to spontaneous large-scale phase separation behavior

Synthesis of a deuterated probe for the confocal Raman microscopy imaging of squalenoyl nanomedicines

• Eric Buchy,
• Branko Vukosavljevic,
• Maike Windbergs,
• Dunja Sobot,
• Camille Dejean,
• Simona Mura,
• Patrick Couvreur and
• Didier Desmaële

Beilstein J. Org. Chem. 2016, 12, 1127–1135, doi:10.3762/bjoc.12.109

• implement the terminal isopropylidene-d6 moiety. The obtained squalenic acid-d6 has been coupled to gemcitabine to provide the deuterated analogue of squalenoyl gemcitabine, a powerful anticancer agent endowed with self-assembling properties. The Raman spectra of both deuterated and non-deuterated

• squalenoyl gemcitabine nanoparticles displayed significant Raman scattering signals. They revealed no differences except from the deuterium peak patterns in the silent spectral region of cells. This paves the way for label-free intracellular trafficking studies of squalenoyl nanomedicines. Keywords

• : deuterium labelling; nanomedicine; Raman spectroscopy; Shapiro reaction; squalene; Introduction Application of nanotechnology to medicine holds promises to profoundly impact healthcare especially to treat severe diseases such as cancer, intracellular infections, neurodegenerative diseases, etc. Indeed, the

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• density variation of functional groups on the PEG scaffold using unsaturated carboxylic acids (crotonic acid, acrylic acid, methacrylic acid) as grafting units for mannose conjugation. We showed by a range of analytic techniques (ATR–FTIR, Raman microscopy, zeta potential and titration) that this

• whole bulk of the particles. This was confirmed via confocal Raman microscopy indicating a homogeneous distribution of functional groups (Supporting Information File 1, S2). The observed increase in grafting density of MA over AA is well established in the literature [13][17][18]. For example, Yang et

• . Acknowledgements The authors thank A. Laschewsky and T. Pompe for support and helpful discussions and A. Masic for RAMAN spectroscopy. Financial support was granted by the German Research Foundation (DFG) through the Emmy Noether program HA5950/1-1, through Research Grant SCHM 2748/3-1 as well as the collaborative