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Search for "absorption" in Full Text gives 943 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Configuration–packing synergy enabling integrated crystalline-state RTP and amorphous-state TADF
Beilstein J. Org. Chem. 2026, 22, 224–236, doi:10.3762/bjoc.22.16
- , making it a suitable candidate for use in advanced optoelectronic devices, such as organic light-emitting diodes (OLEDs), where efficient triplet-state management and delayed fluorescence are highly desired. In different solvents, the UV–vis absorption maxima and band profiles of the compound remain
- essentially unchanged, whereas its fluorescence emission undergoes a monotonic red shift with increasing solvent polarity (or polarizability), accompanied by an enlarged Stokes shift – a typical solvatochromic behavior. The weak solvent dependence of the absorption spectra indicates that the difference in
- emission energy. Consistent with these trends (Figure 2), compound 1 exhibits nearly identical UV–vis absorption across solvents, while its emission shifts bathochromically with increasing polarity, indicating that the luminescence of 1 arises predominantly from intramolecular charge transfer. In a dilute
Synthesis of diaryl phosphates using phytic acid as a phosphorus source
Beilstein J. Org. Chem. 2026, 22, 213–223, doi:10.3762/bjoc.22.15
- total P concentration was measured via absorption spectrophotometry. The coloring agent (2 mL) was added to the diluted samples (25 mL), thoroughly mixed, and left for 15 min. After 15 min, the absorbance of each sample was measured at 880 nm using a V-650 spectrophotometer (JASCO, Tokyo, Japan). A
Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation
Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13
- and Scheme 6). The analysis also suggests the formation of product 2a before water and acid were added. This also indicates that the reaction proceeded through an oxidation/reduction step. UV absorption measurements of the same reaction mixture (a) and pure product 2a (b) dissolved in methanol are
- presented in Figure 2. The formation of product 2a before water and acid were added also follows from the comparison of UV–vis spectra of crude mixture (a) and product 2a (b). According to the previously reported data [51], the absorption maximum in spectrum (a) at 220 nm is caused by the presence of
Streptoquinolines A and B, new antibacterial meroterpenoids produced by Streptomyces sp. TMPU-A0679
Beilstein J. Org. Chem. 2026, 22, 185–191, doi:10.3762/bjoc.22.12
- preparative HPLC, yielding streptoquinolines A (1, 7.50 mg) and B (2, 8.05 mg). The physicochemical properties of 1 and 2 are summarized in Table 1. Compounds 1 and 2 showed characteristic absorption maxima at 200–202, 214, 231–234, 312, and 349–350 nm in UV spectra. Common IR absorption bands at 3414–3427
Improved synthesis and physicochemical characterization of the selective serotonin 2A receptor agonist 25CN-NBOH
Beilstein J. Org. Chem. 2026, 22, 175–184, doi:10.3762/bjoc.22.11
- . Data processing (reduction, merging, and integration) using SAINT and multiscan correction for absorption using SADABS-2016-2 were performed within the Apex4 Suite [25][26][27]. Mercury 4.0 was used to prepare Figure 2a [28]. The crystal data, data collection, and data processing results are given in
- and organic phase, respectively. Each experiment was conducted in triplicate. Molar absorption coefficient and pKa The molar absorption coefficients and apparent pKa values of 1 were determined by spectrophotometry using an inForm instrument from Sirius Analytical (Forest Row, UK). Molar absorption
A new synthesis of Tyrian purple (6,6’-dibromoindigo) and its corresponding sulfonate salts
Beilstein J. Org. Chem. 2026, 22, 167–174, doi:10.3762/bjoc.22.10
- ) [26]. The UV–vis spectra of both 9 and 10 are similar to those of 5,5’-indigodisulfonic acid disodium salt (indigo carmine) and 5,5’,7-indigotrisulfonic acid trisodium salt, as shown in Table 1 [27][28]. When compared to the absorption maximum of 6,6’-dibromoindigo (1), di- and trisulfonation causes a
Design and synthesis of an axially chiral platinum(II) complex and its CPL properties in PMMA matrix
Beilstein J. Org. Chem. 2026, 22, 143–150, doi:10.3762/bjoc.22.7
- chiral platinum(II) complex was synthesized via Sonogashira coupling and subsequent coordination of a pincer ligand to a precursor. The complex exhibited a broad absorption band ranging from 250 to 550 nm in the UV–vis spectrum, with TD-DFT calculations indicating mixed ligand-to-ligand charge transfer
- spectroscopy, as well as high-resolution mass spectrometry (HRMS). Due to its low solubility, single crystals suitable for X-ray crystallographic analysis could not be obtained. Spectroscopic analysis and DFT calculations To elucidate the electronic structure of the platinum(II) complex, UV–vis absorption
- spectroscopy was performed in dilute solution of dichloromethane (1.0 × 10−5 M) (Figure 2a). The absorption spectrum displayed wide range absorption character from 250 to 700 nm with maxima at 430, 331, and 276 nm. To gain deeper insight into the nature of these electronic transitions, density functional
Symmetrical D–π–A–π–D indanone dyes: a new design for nonlinear optics and cyanide detection
Beilstein J. Org. Chem. 2026, 22, 131–142, doi:10.3762/bjoc.22.6
- ) efficiency [14][15][16]. Indanones are highly conjugated with a planar structure, which favors overlap between the molecules. They are building blocks for many compounds, such as organic materials for optoelectronic and NLO applications [17][18]. Research shows that the absorption wavelength of the region
- the absorption bands towards the NIR region. Syntheses of dyes were carried out using the conventional method and the microwave irradiation (MWI) method, and the results were compared with yields and reaction times. Absorption spectra in solvents of different polarities were examined to determine the
- photophysical properties of the dyes. The sensitivity/selectivity properties of the dyes to anions were investigated in DMSO and aqueous media, revealing that the dyes were selectively responsive only to cyanide anions. Changes after interactions were determined through absorption spectra and color changes
Competitive cyclization of ethyl trifluoroacetoacetate and methyl ketones with 1,3-diamino-2-propanol into hydrogenated oxazolo- and pyrimido-condensed pyridones
Beilstein J. Org. Chem. 2025, 21, 2716–2729, doi:10.3762/bjoc.21.209
- frequencies of the carbonyl function (ν 1633–1593 cm−1) and N–H, O–H groups (ν 3435–3126 cm−1), which indicates their participation in the hydrogen bond formation [67]. On the other hand, the IR spectra of hexahydrooxazolo[3,2-a]pyridones 5a–c contain intense absorption bands of the C=O function at ν 1652
Chemoenzymatic synthesis of the cardenolide rhodexin A and its aglycone sarmentogenin
Beilstein J. Org. Chem. 2025, 21, 2637–2644, doi:10.3762/bjoc.21.204
- absorption and metabolism, and specific moieties like rhamnose can enhance CG potency markedly by more than 25 times [1][7]. In addition, the -OH groups on the steroids’ structure also play an important role on their activity. However, these compounds are mainly isolated from plants or animals, which not
Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids
Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203
- = 0.546), with an excitation wavelength of 366 nm [83][84][85]. Nevertheless, no measurable quantum yield was observed for the fluorescence process. A solvatochromic study was conducted by measuring the UV–vis absorption and fluorescence spectra of compounds 3n (Figure 7) and 4n (Supporting Information
- from rhodanine (3n) exhibited an intense absorption band in the range of 462–481 nm, related to the π→π*-type transitions. Additionally, weaker, broad absorption bands were observed below 350 nm. In contrast, the thiazolidine-2,4-dione derivative 4n displayed a blue shift, with maximum absorption band
- (Scheme 8) [92]. Finally, an investigation of the influence of pH on the absorption and fluorescence spectra in aqueous solution was carried out under various pH values for compounds 3n (Figure 8) and 4n (Figure S252 in Supporting Information File 1), as changes in pH are known to significantly affect
Silica gel with covalently attached bambusuril macrocycle for dicyanoaurate sorption from water
Beilstein J. Org. Chem. 2025, 21, 2604–2611, doi:10.3762/bjoc.21.201
- . Additionally, a new absorption band at 1558 cm−1 was observed in the spectra of SG-NHCO-BU1 further confirming covalent attachment of BU1 through an amide bond. In the case of SG-BU1, a C=O vibrational band is observed at 1705 cm−1, which corresponds to the vibration of the C=O of BU1 carboxylic acid groups
- 1 M KOH, followed by addition of dicyanoaurate ([Au(CN)2]−) to the supernatant. It was shown previously that the absorption spectrum of dicyanoaurate in aqueous solution changes upon formation of an inclusion complex between the anion and a bambusuril macrocycle [17]. A solution of dicyanoaurate in
- 1 M KOH was titrated by BU1 and the changes in the absorption spectra of the anion were in agreement with those previously reported in pure water (Figure 1B). Dicyanoaurate absorption bands with maxima at 239 and 229 nm decreased in their intensity in the presence of BU1, while a new band appeared
Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition
Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196
- position. Therefore, dihydroxylation [37] readily converted alkene 11 to diol 12 as a mixture of inseparable isomers. Without purification, oxidative cleavage with NaIO4 resulted in a compound with strong UV absorption, which was eventually identified as enone 14 (Scheme 3). It is assumed that the
Pentacyclic aromatic heterocycles from Pd-catalyzed annulation of 1,5-diaryl-1,2,3-triazoles
Beilstein J. Org. Chem. 2025, 21, 2524–2534, doi:10.3762/bjoc.21.194
- the NMR timescale. These trends were observed similarly for the other analogs of this study (see Supporting Information File 1). Optoelectronic properties of each annulated product and its respective control compound were examined via UV–visible absorption and emission spectroscopy. Figure 6 shows the
- Information File 1). Table 3 summarizes the observed λmax values for absorption and emission bands for each compound in this study. Due to their structural rigidity, annulated compounds comprised of quinoline or isoquinoline subunits generated emission signals with greater intensity and smaller Stokes shifts
- isoquinoline subunits. Heterocycle subunit identity and triazole C/N connectivity influenced the annulation reaction efficiency. Aromatic π-system expansion resulting from annulation was characterized by NMR, absorption and emission spectroscopy. Five benzotriazolophenanthroline regioisomers sharing structural
Effect of a photoswitchable rotaxane on membrane permeabilization across lipid compositions
Beilstein J. Org. Chem. 2025, 21, 2498–2512, doi:10.3762/bjoc.21.192
- the LUVs at 10 mol % relative to the total lipid content. UV–vis spectra recorded before irradiation showed an absorption band around 372 nm, corresponding to the π→π* transition of the E isomer (Figure 3, left column, black trace). Upon irradiation at 370 nm for 1 minute, two new peaks appeared at
- conversion is typical for this type of photoswitches, owing to the spectral overlap between the π→π* and n→π* transitions. Importantly, these spectral signatures were consistent across all lipid compositions, indicating that the different membrane phases did not induce measurable shifts in the absorption of
- rotaxane 1. LUVs containing rotaxane 1 were subjected to ten cycles of alternating irradiation at 370 nm and 467 nm, with UV–vis spectra recorded after each exposure. Figure 3 (right column) shows the changes in absorption at 365 nm, reflecting the photoswitching and photoreversibility of rotaxane 1 across
Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate
Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191
- , the use of TT frameworks for semiconductors has led to significant progress in organic field-effect transistors (OFETs), organic photovoltaics, organic light-emitting diodes, and chemical sensors [1][2][3]. For instance, TT-containing copolymers have shown high hole mobility, strong absorption in the
Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds
Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185
- simple building blocks [72]. The main feature of light-induced transformations is the involvement of electronically excited states that occur during photon absorption, leading to the formation of reactive intermediates causing significant changes in chemical compound reactivity. As a result, light energy
Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs
Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181
- ) and WDG (rigid fluorene backbone), were synthesized via Friedel–Crafts reactions. Their iodide (I−) recognition properties were systematically explored using 1H NMR, UV–vis absorption, and fluorescence spectroscopy. Quantitative analysis via the Benesi–Hildebrand equation and nonlinear fitting
- rotationally restricted, all its accessible conformations constitute a subset of PBG's conformations. The binding constants and conformational change mechanisms of the two analogs were quantitatively evaluated by proton nuclear magnetic resonance spectroscopy (1H NMR), ultraviolet–visible absorption
- by the two structural analogs, we added a commercially available tetrabutylammonium salt (TBAI) to the body dissolved in CDCl3 (TBAI has a good solubility in CDCl3) and studied the interaction between the receptor and iodide ion by 1H NMR titration, UV–vis absorption spectroscopy and fluorescence
Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications
Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179
- 2007 by Zhou and co-workers [74]. The spiropyran was positioned on the axle and served a dual purpose: as a recognition site and stopper. Photoisomerization led to the reversible shuttling of the macrocycle, which produced a visible absorption output signal that can be seen with the naked eye. Later
Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis
Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177
- , 108d) underwent the desired photochemical reaction (Scheme 13b), yielding spiroacetals 109a, 109b, and 109d following CAN (cerium(IV) ammonium nitrate) oxidation. In contrast, C7-methoxy-substituted analogs (108c, 108e) remained unreactive. Reactivity correlated with UV–vis absorption profiles
A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines
Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168
- bond. Therefore, the π-electron conjugation is widespread almost over the chromophores. However, the UV spectrum of 1–ʟ-alaninol conjugate (S)-2a shows an intense absorption, maintaining the nature of methoxybiphenyl chromophore. The absorption band at 259 nm is attributed to the π–π* transition
Understanding the origin of stereoselectivity in the photochemical denitrogenation of 2,3-diazabicyclo[2.2.1]heptene and its derivatives with non-adiabatic molecular dynamics
Beilstein J. Org. Chem. 2025, 21, 2007–2020, doi:10.3762/bjoc.21.156
- , experimentally, there is an ensemble of non-equilibrium geometries. To get a more realistic understanding of the absorption, we generated 500 geometries using the Wigner-sampling method to generate an ensemble of energetically accessible non-equilibrium geometries. We computed the gas-phase vertical excitation
- energies (S0 → Sn, n = 1, 2, 3) and corresponding oscillator strengths of the Wigner-sampled structures of 1, 3 and 5 to explore the nature of electronic excitations to the FC regions. This allowed us to predict an absorption spectrum with normalized oscillator strengths (S0 → S3). Figure 2 shows the
- computed absorption spectra of 1, 3, and 5. Figure 2 shows the 1, 3, and 5 computed absorption spectra with three λmax peaks. The S0 to S3 has a peak centered from 179 to 181 nm and corresponds to a majority nNN(σCN) → Ryd, the peak centered from 190 to 194 nm corresponds to a majority nNN → π* from S0 to
Aryl iodane-induced cascade arylation–1,2-silyl shift–heterocyclization of propargylsilanes under copper catalysis
Beilstein J. Org. Chem. 2025, 21, 1984–1994, doi:10.3762/bjoc.21.154
- it improves lipophilicity, oral absorption and biological activity [25]. Results and Discussion Arylation of aliphatic chain-containing propargylsilanes We started our investigation with the arylation of aliphatic chain-containing propargylsilanes. The starting material – tert-butyl(hept-1-yn-3-yl
Photochemical reduction of acylimidazolium salts
Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153
- catalytic photoenolization/Diels–Alder (PEDA) reaction [14][15]. In this process, the NHC fragment present in the acylazolium species influences the absorption wavelength and fundamental photochemical reactivity of the C=O bond, enabling a “ketone-like” photoreaction from otherwise unsuitable carboxylic
- identity of the active light-absorbing species in the reaction mixture. UV–vis spectra of the benzoylazolium starting material 1 at different concentrations in the acetonitrile reaction solvent were accordingly measured. Although exhibiting maximum absorption at wavelengths significantly shorter than that
- emitted by the light sources used (latest λabs,max = 271 nm), a significant absorption tail up to ca. λ = 400 nm was observed at higher concentrations, indicating that the starting material could potentially absorb the incident light directly. This rationale is consistent with the increase in reduction
Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation
Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149
- absorption maximum of MC1 is more redshifted by 42 nm compared to MC2, which is attributed to the extended conjugation after the fusion of one pyrene unit. Similarly, both MC1 and MC2 have higher ΦF values of 0.45 and 0.69 than compound MC3 (ΦF = 0.13). The optical energy bandgaps were determined to be 2.48
- well as four negative Cotton effects at 288, 317, 331, and 432 nm, respectively. (−)-MC1 exhibits a mirror image with the opposite signals to that of (+)-MC1. The maximum absorption dissymmetry factor (gabs) value of 1.1 × 10−3 at 453 nm is observed (Figure 5b), which is derived from the S0→S1
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