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Search for "chromophore" in Full Text gives 163 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions
Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195
- ions at submicromolar concentrations always by means of NMR spectroscopy [33]. Nevertheless, sensing by UV–vis or fluorescence spectra was hard to realize, for there is no chromophore in the frameworks. While hemicucurbit[n]urils with improvement in solubility, they still remain poor in derivatization
- . These adverse properties have impeded the development of hemicucurbit[n]urils to some extent. Introducing aromatic fragments into macrocycles which have no chromophore is a viable strategy to expand the scope of their application. Ganin et al. [34] reported the synthesis and formation of several
- as reactive sites for derivatization, at the same time allowing for formation of coordination or hydrogen bonds with guests, and the aminobenzene unit as a chromophore could improve the optical properties. With this novel macrocycle in hand, the interactions with some metal cations have been
Progress and challenges in the synthesis of sequence controlled polysaccharides
Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129
Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications
Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116
Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties
Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81
- compounds 4a–f and 5a–e were identified and fully characterized by NMR-spectroscopic analysis (1H, 13C, COSY, HSQC, HMBC), mass spectrometric data and elemental analyses. Absorption and emission properties The absorption properties of the derivatives 5a–e resemble the ones of the berberine chromophore with
- -aryl substituent to the berberine chromophore. The latter has been shown to operate also in resembling cationic, biaryl-type dyes [42][43]. Along the same lines, the low intrinsic emission quantum yield of the parent berberine (1a) has been suggested to result from an internal charge transfer (ICT
Insight into functionalized-macrocycles-guided supramolecular photocatalysis
Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15
- quantum yield of 3.8 × 10−2 and 0.4, respectively. In contrast, for flavins without the zinc(II)–cyclen unit, only small amounts of product were observed, and the quantum yield was 30 times lower compared to that of the assembly with the flavin chromophore possessing a binding site. The mechanism may be
- rim of the CDs could also be optimized, leading to the conformational fixation of both the sensitizer and the guest within the chiral cavity and producing the high ee values. For 8c and 8d, the self-inclusion of the aromatic chromophore might be interrupted, resulting in the long distance from the
UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation
Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240
- probe the entire chromophore and are sensitive only to changes in the electronic structure of the molecule. In contrast, vibrational spectroscopic techniques such as infrared (IR) and Raman spectroscopy provide a much more detailed picture at the level of chemical bonds since they probe the intrinsic
- and 215 nm. Both absorption bands can be attributed to π→π* transitions within the GCP chromophore. On the other hand, GCI ethyl amide exhibits a slightly red-shifted absorption band covering the entire region below 370 nm with two peaks at 320 and 244 nm which are also assigned to π→π* transitions of
- the GCI chromophore. The red-shift in the spectral positions of the GCI peaks with respect to those of the GCP peaks is due to the extended conjugation induced by the indole ring of GCI. We chose 266 nm and 244 nm as laser excitation wavelengths for UVRR spectroscopy. The 266 nm excitation was chosen
Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes
Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219
- sensing [1][2][3][4][5][6]. The analyte can be detected by relying on the enhancement of the Raman scattering intensity, if it is bound close to the gold surface (surface enhanced Raman scattering, SERS), for example, or by the release from the metal surface of a chromophore the fluorescence of which is
- quenched in the absence of the analyte by Förster resonance energy transfer (FRET). In the latter case, the analyte binding either causes the chromophore to dissociate from the nanoparticle, if it is bound noncovalently (indicator displacement), or to move away from the metal surface as a consequence of a
- conformational reorganization of the linker connecting the chromophore with the surface. The likely most frequently used strategy of analyte detection relies on the color change of AuNP solutions resulting from analyte-induced nanoparticle crosslinking. Depending on whether soluble or insoluble aggregates are
Recent developments in enantioselective photocatalysis
Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197
- different approaches have been developed that use a single catalyst. Alemán et al.’s approach combines the two catalytic motifs into a single bifunctional catalyst 38, using thioxanthone as the chromophore (Scheme 5) [31]. The catalyst 38 was then applied to known reactions such as the α-functionalization
- by Bach to the deracemisation of allenes rac-194 (Scheme 29) [85]. The proposed mechanism proceeds through configurationally isomeric hydrogen bonding complexes 195 and 195’, with subsequent photoexcitation of the thioxanthone chromophore leading to racemisation of the allene through a triplet state
- intermediate 196. In 195 there is additional steric repulsion between the large R group and the thioxanthone that is not present in 195’, which results in a smaller association constant and a larger calculated separation between the allene and the chromophore in 195 (r = 510 pm) relative to 195’ (r = 363 pm
Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties
Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189
- organic NLO chromophore is related to the presence of donor (D) and acceptor (A) groups linked through a π-conjugation path and is characterized by a large first-order hyperpolarizability value (β). However, a small energy gap between the HOMO and the LUMO (Egap) is an important indicator for high NLO
Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator
Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185
- for reaching thermodynamic equilibrium. It should be stressed that all changes in the 330–400 nm range could be attributed dominantly to the NDI chromophore, since absorbance of GCPs in this range is negligible. Absorbance changes of large aromatic chromophores upon DNA or RNA addition can happen for
- many reasons, the most common ones being solvatochromic effects or aromatic stacking interactions. In this particular case, the NDI chromophore in threading intercalation has to be stacked with two base pairs, causing typical hypochromic and bathochromic effects. However, the positioning of the NDI
- chromophore in the DNA/RNA grooves aside expulsion of water solvating the NDI, also allows for aromatic interactions, either edge-to-face with base pairs or even with another NDI molecule (aggregation within groove). Both events strongly affect the UV–vis spectrum of the NDI chromophore. In any case, strong
Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis
Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183
- transformation. There are four prerequisites for TTET to be effective: i) The PS must have a chromophore that can absorb light, 2) the energy gap between S1{PS} and T1{PS} must be higher in energy than the energy gap between S1{Sub} and T1{Sub}, iii) ISC between S1{PS} and T1{PS} must be rapid to ensure a high
Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA
Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170
- access to large libraries of close analogues. Further, in such peptide-based chromophore systems, a multitude of different chromophores/fluorophores [10] could allow fine tuning of spectroscopic responses to various DNA/RNA sequences. With this concept in mind, Piantanida and co-workers recently
- ][13][14][15][16]. These inspiring results encouraged us to broaden the palette of available amino acid (AA)–chromophore conjugates. Therefore, in this work we have chosen a naphthalene diimide (NDI) chromophore [17][18][19][20], a well-known DNA/RNA binding moiety, which differs from previously used
- both, the minor and major groove of the polynucleotide. Such bulky groups positioning requires the DNA double helix to shortly open at a binding site and close upon threading intercalator insertion. Also, the chosen NDI chromophore is characterised by easily tuneable emission wavelengths [23], and
Heterogeneous photocatalysis in flow chemical reactors
Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125
[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin
Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110
- reactions [8]. Azomethine ylides can be formed by several photochemical or thermal catalytic methods [5][6][7], including photodecarboxylation of phthalimide derivatives of α-amino acids such as N-phthaloylglycine (1) [9][10]. Phthalimide is a versatile chromophore that has been used in the synthesis of
- the macrocyclic host affected the stereochemistry of the reaction. Moreover, we studied photodecarboxylation reactions initiated by the phthalimide chromophore [17][18][19] and applied them in cyclizations with memory of chirality [20] and diastereoselective peptide cyclizations [21
Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore
Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98
- precursors of the photoconvertible chromophore of the Kaede protein, an imidazolone with outstanding photophysical properties [31][32][33][34][35][36][37][38]. It is clear from Figure 2b that the molecular skeleton contains different reactive functional groups, which offer a variety of structural
- findings were also confirmed by analysis of the 13C NMR spectra. Conclusion The synthesis of cyclobutane 1,3-diaminotruxillic bis-amino acids has been achieved with full stereoselectivity (ε-isomer) starting from polyfunctional oxazolones 2 derived from the chromophore of the Kaede protein in three steps
Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates
Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82
- quinolizinium or the coralyne chromophore, respectively, with maxima at 386 nm (3a) or 437 nm (3b) in MeCN (Figure S1A, Supporting Information File 1) [60][61]. Notably, the photoinduced electrocyclic ring-opening reaction of these substrates to give the respective merocyanine forms could not be accomplished
Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties
Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81
- up to 67%, while their bandgaps and chiroptical responses could be tuned by twisting the bipyrrole chromophore. The solvatochromism and apparent superradiance of these chromophores indicated a potential involvement of solvent-induced symmetry-breaking charge transfer in the excited state [34]. Here
- DFT calculations (Figure 1 and Supporting Information File 1). The length of the linker (n) in cNDAnX and cNMInX controls the in- and out-of-plane geometry of the chromophore. The observed changes can be expressed in terms of two parameters: α, the angle between the monopyrrole axis and the N–N vector
p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies
Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33
- functional on the optimized (B3PW91/6-31G(d)) ground state geometries. It is shown, that 11 has lower excitation energies than 12 and this must be reflected in the difference between the two substituents (Cl and NO2). Although the two molecules have essentially the same basic chromophore groups when we
Two new aromatic polyketides from a sponge-derived Fusarium
Beilstein J. Org. Chem. 2019, 15, 2941–2947, doi:10.3762/bjoc.15.289
- with the absorption bands at 234, 266, 313, 499, and 533 nm was closely similar to that for 1-acetyl-2,4,5,7,8-pentahydroxyanthraquinone from a fungus Geosmithia [24], suggesting the presence of a common chromophore in 1. Two highly substituted benzene rings were assembled by analysing the HMBC
Influence of the cis/trans configuration on the supramolecular aggregation of aryltriazoles
Beilstein J. Org. Chem. 2019, 15, 2881–2888, doi:10.3762/bjoc.15.282
- from 0° or 180°, since this interaction is governed by an equation with a vectorial product. The lack of exciton pairwise interactions between the two chromophores in positions 1 and 2 of each molecule could be due to the intercalation of a third chromophore between the two former in a parallel
Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission
Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274
- groups to control a wide variety of biological process photoreversibly [8][9]. Furthermore, chemists have paid attention to spectral tuning of the AB chromophore [10][11]. Recently, an improved set of fluorine-substituted AB photochromes was developed by Hecht and co-workers [12][13]. ABs with two or
- four fluorines and electron-withdrawing groups at the para substituents all maintained the superb chemical properties of the parent tetrafluoro-(4F)AB chromophore [12]. Mild electron donation effectively destroys the beautiful separation of absorption bands of the n–π* transitions, and with it the
- in Figure 1). Our data is similar to that recently reported by Gorostiza and co-workers for a monofluorinated AB photochrome [18] (core structure shown in Figure 1 as "1FAB"). This monofluoro-(1)FAB chromophore is much less electron rich than MeO-2FAB, so it is perhaps not surprising that 2FAB cannot
Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences
Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262
- effects of base and temperature on Michael addition–cyclocondensation sequences in the formation of α-pyrones and/or 1H-pyridines starting from diversely substituted alkynones and cyanoethylacetate. This bifurcating domino process furnishes small chromophore libraries which were characterized by
- shift to 673 nm (Table 8, entry 7). Most remarkably, the regioisomers 6c and 6e differ quite significantly with respect to their fluorescence quantum yields Φf. While chromophore 6e only emits with an efficiency of 1%, the regioisomer 6c accounts for an extraordinarily high relative quantum yield of 99
Plasma membrane imaging with a fluorescent benzothiadiazole derivative
Beilstein J. Org. Chem. 2019, 15, 2644–2654, doi:10.3762/bjoc.15.257
- the BTD-4APTEG molecule, which is the net result of its electron density withdrawal character. The HOMO orbital distributes over the BTD basic scaffold and the vicinal ring but does not involve participation of the side chain of the chromophore. The electron density difference between the ground S0
- and first excited state S1 (∆ρ = ρS1 − ρS0), as shown in Figure 4D, highlights the directionality of the electron density transfer with a great deal of ICT between the cationic heterocycle and the BTD core, which stabilizes the excited state of the synthesized chromophore. These theoretical results
Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence
Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254
- * transition bands in the wavelength range of 330–400 nm with characteristic vibronic fine structure were observed. Further, the dyes have a sharp peak at 322 nm that is assigned to the isoquinoline chromophore. The only exception is dye 18 where this peak is hidden under a strong absorption band corresponding
Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses
Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221
- dendrimers have been designed to study this possibility. All multichromophoric compounds performed better than the model chromophore. An amplification factor of up to 2.5 per chromophoric subunit was obtained for the σ2max/εmax response (Figure 4). Interestingly, the response of the dimers increases from the
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