Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes

• Koki Ikemoto and
• Hiroyuki Isobe

Beilstein J. Org. Chem. 2024, 20, 1207–1212, doi:10.3762/bjoc.20.103

• appearing at 250 nm (Figure 2). As shown with the reference spectra of [6]CMP and [8]CMP, the absorption at 280 nm was absent for the corresponding hydrocarbon congeners. These results showed that the nitrogen-dopants induced novel transitions for photoexcitation. Crystallographic analyses revealed the

• acid was necessary for this effect to be observed with a maximum equivalent of TFA at 2 × 105, and the absorption band at the longest wavelength gradually shifted as shown in Figure 5a. When we added TFA to a solution of a reference compound 6 having inward-focused nitrogen atoms with a maximum

• equivalent of TFA at 2 × 105 [13], bathochromic shifts were also observed. However, unlike the case with 3a, gradual absorption shifts were not observed, and the absorption changed from 299 nm to 320 nm with an isosbestic point at 303 nm as shown in Figure 5b. This observation indicated that the protonation

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

• Jinmin Gao,
• Liyuan Li,
• Shijie Shen,
• Guomin Ai,
• Bin Wang,
• Fang Guo,
• Tongjian Yang,
• Hui Han,
• Zhengren Xu,
• Guohui Pan and
• Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

• + AlpJ; (d) 8 + AlpJ + SOD (5,000 U/mL); (e) 8 + Flu17 + SOD (5,000 U/mL). UV absorption at 266 nm (black line) and 313 nm (red line) are displayed for each reaction. Ring cleavage and ring rearrangement reactions in the biosynthesis of atypical angucyclines. Proposed catalytic mechanism of cofactor

Two-fold addition reaction of silylene to C₆₀: structural and electronic properties of a bis-adduct

• Masahiro Kako,
• Masato Kai,
• Masanori Yasui,
• Michio Yamada,
• Yutaka Maeda and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

• ) spectrum. Fullerene derivatives are well-known to show characteristic absorption spectra depending on the addition pattern. As shown in Figure 2, the spectrum of 3 exhibited an absorption maximum at 515 nm, which is similar to those of the e′ and e′′ isomers of C60[C(C6H4OMe)2]2 and C60[C(C6H4OMe)2][NCOOEt

• . Reagents were used as purchased unless otherwise specified. The 1H and 13C NMR measurements were conducted on a JEOL ECA-500 spectrometer (JEOL Ltd.). Absorption spectra were measured using a UV-3150 spectrophotometer (Shimadzu Corp.). Cyclic voltammograms and differential pulse voltammograms were recorded

• ) Å3, T = 99.9(2) K, Z = 4, 67750 reflections measured, 19176 unique (Rint = 0.0321), which were used for all calculations, 2θmax = 63.262; min/max transmission = 0.921/1.000 (absorption correction was applied by multi-scan method); The structure was solved using a direct method using olex2.solve 1.5

Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• isobenzofurans 2, 3 and 23 were studied by UV–vis and fluorescence spectroscopies (Figure 5). Compound 2 is devoid of ortho groups on its 1,3-diphenyl substituents and shows the longest wavelengths of absorption (λmax = 415 nm) and emission (emission λmax = 484 nm) in this series, consistent with a more highly

• conjugated π-system in which the 1,3-diphenyl substituents lie flat or nearly flat relative to the isobenzofuran backbone. Likewise, compound 2 is yellow while compounds 3 and 23 are colorless. Compounds 3 and 23 show similar absorption (λmax = 364 and 360 nm for 3 and 23, respectively) and emission (λmax

• Center using a peak-matching protocol to determine the mass and error range of the molecular ion, and employing electrospray as the ionization technique. UV–vis absorption spectra were measured with a Varian Cary 50 Scan UV–visible spectrophotometer and corrected for background signal with a solvent

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

• Akanksha Ashok Sangolkar,
• Rama Krishna Kadiyam and
• Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

• barriers were accounted using the DLPNO-CCSD(T) and (8,8)-CASPT2 methods, respectively. The photophysical properties including the absorption onset, excitation wavelengths, and the absorption intensities were extensively investigated with the time-dependent calculations. The result provides information on

• modification, the storage energy of 158.57 kJ/mol, energy storage density of 1.48 MJ/kg, TBR barrier of 136.36 kJ/mol, and the absorption onset of 305.00 nm is achieved in acetonitrile. These values are substantially higher when compared with the storage energy (96.06 kJ/mol), energy storage density (1.04 MJ

• photoswitching is depicted in Figure 1a. The NBD/QC couple is capable to chemically store huge amounts of solar energy due to the incorporation of large strain during the photoconversion and is thus recognized as a potential MOST candidate [8][9][10][13]. However, the optical absorption of unsubstituted NBD in

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• and its high thermal stability. Optical properties The electronic properties of the DCPQs 1a–6a and DPQDs 1b–7b were explored by UV–vis absorption spectroscopy in dimethyl sulfoxide (DMSO) at 25 °C (Figure 3). The electronic absorption spectra of DCPQs exhibited structureless bands with λmax values

• 40 μM solutions of the DCPQs and DPQDs on a Cary 100 Bio spectrophotometer using 1 cm quartz cells. All solvents were HPLC grade (purchased from Fisher) and stored over 4 Å molecular sieves. The absorption intensity at λmax was then plotted against the concentration in all cases to confirm, by

• of electron-accepting azaacene derivatives as liquid-crystalline materials by Takeda et al. (b) [24]. Transformation of Yamashita’s DCPQs to H-bonding capable DPQD derivatives discussed in this work (c) [25]. TGA of 1a–6a (a) and 1b–7b (b) obtained at 10 °C/min under nitrogen. Absorption spectra (20

Spin and charge interactions between nanographene host and ferrocene

• Akira Suzuki,
• Yuya Miyake,
• Ryoga Shibata and
• Kazuyuki Takai

Beilstein J. Org. Chem. 2024, 20, 1011–1019, doi:10.3762/bjoc.20.89

• ). Here, it should be noted that the vibrational spectra are more distorted due to electromagnetic shielding effects by the conductive nature of graphene-based materials upon IR excitation. Thus, the “apparent” negative absorption peak in the spectrum of FeCp2-ACFs-55 is caused by the phase shift of the

Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• synthesized by other methods and the single Suzuki reaction on uracil is well studied [42][69][70][71]. Physical properties The photophysical properties of selected derivatives were investigated by steady-state absorption and photoluminescence spectroscopy. The influence of the substitution pattern on the

• photophysical properties is displayed in Figure 4. Corresponding photophysical data and quantum yields are described in Table 2. The analysis of the absorption spectra revealed that the spectra can be divided into a short-wave and long-wave region. In the long wavelength region (350–500 nm) all measured

• compounds show a very similar absorption band, indicating that the first transition state (S0 → S1) does not seem to be affected by the substitution pattern. Furthermore, all compounds show broadened absorption bands and no major differences in the first absorption band were observed. The greatest

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• these homologs exist mostly as dimers in solution. Next, the heme incorporation of the isolated homologs was measured. UV–vis absorption spectra showed that each NnlA homolog exhibited characteristic Soret absorption features consistent with heme binding to the protein (Figure 3). In addition, the A412

• buffer is 100 mM tricine 100 mM NaCl buffer at pH 7.5. Dashed grey lines represent elution volumes of molecular mass standards. Theoretical molecular weights are as follows Vs NnlA: 21,869 Da; Mr NnlA: 20638 Da; Pd NnlA: 18,473 Da; Ms NnlA : 18,239 Da; and Ps NnlA: 19,042 Da. UV–vis absorption spectra of

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• generally enhanced in polar environments [44][45][46]. The list of the solvents used to solubilize the molecules is summarized in Table S1, Supporting Information File 1. Spectral characterizations of 5a and 5b The absorption spectra of C60–oligo-Lys (5a) and C60–oligo-Glu (5b) were recorded in Milli-Q

• ® water (pH 7.0) and in TRIS buffer (pH 9.0), respectively (Figure 4). The spectrum of C60–oligo-Lys (5a) was in good agreement with that typically observed for C60 monoadduct derivatives [47]. The electronic spectra of the fulleropyrrolidines were characterized by notable π–π* absorption in the UV region

• . Additionally, 5a exhibited broad absorption in the visible region with relatively low intensity as well as a distinctive sharp peak at around 430 nm [48]. However, those features were not observed in the spectrum of C60–oligo-Glu (5b), presumably due to the aggregation [32]. The 1H NMR spectrum of C60–oligo

Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• spectra of porphyrins 2 and 3 exhibit the absorption band at 3321 cm−1 corresponded to NН stretching vibrations. Bands at 2127 cm−1 confirmed the presence of the N3 group in porphyrins 2 and 7. The IR spectra of porphyrins 5–7, 11, 12, 14, 18–20, 23, 24, and 26 exhibit absorption bands at 2605–2609 cm−1

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• ) Radical trapping experiments with TEMPO. b) Exclusion of possible intermediate. c) Subjecting the product Z-6i to the standard conditions. d) The control reaction with HPd(PPh3)2Cl. e) UV–visible absorption analysis. Proposed mechanisms for the carboamination of 1,3-dienes or allenes with diazo esters and

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• absorption spectra showed broad absorption in the visible region with an absorption maximum at 711 nm, which was known to show a characteristic pattern of functionalized fullerene having an addend on a [6,6] bond [26]. As mentioned above, a distinctive feature of this reaction is the significantly lower

• , external standard), and carbon of the solvent for 13C (53.84 ppm, CD2Cl2). High-resolution matrix-assisted laser desorption ionization (HR-MALDI) mass spectra were obtained on a Bruker solariX 12T mass spectrometer with dithranol as a matrix. UV–vis absorption spectra were measured on a JASCO V-670 and a

• values of Li+@C60 are also listed as a reference. Supporting Information Supporting Information File 50: HPLC profiles, NMR, HRMS, UV–vis absorption spectra, and computational details. Acknowledgements We thank to Dr. N. Ikuma for a fruitful discussion. Generous support from the FRIS CoRE, Tohoku

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• characteristic UV absorption around 270 nm. The molecular formula of 1 was determined to be C44H66O15 based on the HRESIMS data. The NMR data for 1 are summarized in Table 1. The 1H NMR spectrum of compound 1 was similar to those of known polycavernosides but matched none of them, suggesting that 1 was a new

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Irina V. Dubonosova,
• Olga Yu. Karlutova,
• Oleg P. Demidov,
• Alexander D. Dubonosov and
• Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

• change of the solutions from yellow to dark orange. Subsequent selective interaction with AcO− led to the restoration of the initial absorption and emission properties. Thus, the obtained compounds represent dual-mode “on–off–on” switches of optical and fluorescent properties under sequential exposure to

• absorption spectra, induced in one or both directions by absorption of electromagnetic radiation [1][2][3][4]. Due to the different structures and the different optical and emission properties of these forms, photochromic compounds are used in 3D optical memory devices, photoswitches of different types

• -wavelength absorption at 458 nm, while acylation led to a hypsochromic shift of the maximum in compounds 2a–c to 423–426 nm (Table 1). The intensity of this absorption band decreased with increasing steric hindrance in the order R = acetyl (i.e., 2a) > propionyl (i.e., 2b) > phenylacetyl (i.e., 2c). N

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• arms with planar Pt complexes are parallel and the distance between them allows for the intercalation of another terpy-Pt complex. The guest intercalation coupled with the induction of short-range Pt–Pt interactions was followed by UV–vis absorption and emission spectroscopies with characteristic MMLCT

• chiroptical properties with a large change in the absorption spectra and a bathochromic shift in the emission maximum. This system represents a rare example of a multi-output readout system, showing responses in ECD, fluorescence, and CPL activity. The authors later reported a similar system with a bipyridine

• bearing this time alkynylplatinum(II)–terpyridine arms 21 [53]. The intercalation of an alkynylplatinum(II)–terpyridine complex system results in a large absorption band in the visible domain (λmax,abs = 515 nm) and an enhanced emission band in the infrared (λmax,emission = 780 nm) attributed to the

A new analog of dihydroxybenzoic acid from Saccharopolyspora sp. KR21-0001

• Rattiya Janthanom,
• Yuta Kikuchi,
• Hiroki Kanto,
• Tomoyasu Hirose,
• Arisu Tahara,
• Takahiro Ishii,
• Arinthip Thamchaipenet and
• Yuki Inahashi

Beilstein J. Org. Chem. 2024, 20, 497–503, doi:10.3762/bjoc.20.44

• preparative HPLC of the crude extract, 7.9 mg of 1 was obtained (Scheme 1). Table S1 (Supporting Information File 1) shows the physicochemical properties of 1, which is a yellow oil soluble in MeOH and DMSO. The UV absorption maximum of 1 was at 286 nm (ε = 10238 M−1·cm−1). The molecular formula of 1 was

Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793

• Zhen Ying,
• Xiao-Ming Li,
• Sui-Qun Yang,
• Hong-Lei Li,
• Xin Li,
• Bin-Gui Wang and
• Ling-Hong Meng

Beilstein J. Org. Chem. 2024, 20, 470–478, doi:10.3762/bjoc.20.42

• crystallographic analysis of compounds 1–3 [16]. Compounds 1–3 were crystallized in MeOH. All crystallographic data were collected on a Bruker Smart-1000 or Bruker D8 Venture CCD diffractometer using Cu Kα radiation (λ = 1.54178 Å). The data were corrected for absorption by using the program SADABS [17]. The

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• [10]CPP and [5]CPP2+ decreased and increased, respectively, upon complex formation and clearly indicate the partial electron transfer from [10]CPP to [5]CPP2+ in the complex. The involvement of a CT in the complex was further supported by the UV–vis–NIR absorption spectra. The complex showed several

• absorption bands in the visible region and characteristic broad absorption bands extending to the NIR region (≈2000 nm) (Figure 4, black line). According to time-dependent density functional theory (DFT) calculations at the ωB97-XD/6-31G* level of theory, the NIR absorption of the most thermodynamically

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• absorption of light, an excited photocatalyst (*PC) engages in single-electron transfer (SET) with either donor (D) or acceptor (A) molecules (Scheme 3) [8][36]. Accordingly, a reductive quenching mechanism (path a) will operate when an excited photocatalyst effects the one-electron oxidation of a

• (B2cat2) [63] (Scheme 15A). UV–vis absorption measurements showed that a mixture of a model NHPI ester with B2cat2 in dimethylacetamide (DMA) formed a new charge-transfer band in the visible region (>390 nm), which was attributed to the formation of EDA complex 74 (Scheme 15B). Under blue light

• absorption spectra of PTH1 was observed, suggesting the formation of a charge transfer complex of the type 88 [68] (Scheme 17A). tert-Butyl radical (64), along with additional 2° and 3° alkyl radicals, resulting from these EDA complexes were harnessed in C(sp3)-heteroatom bond forming reactions [69], and in

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• fragment gave rise to the appearance of an additional long-wavelength absorption band with λmax = 520 nm and ε = 9200 M−1⋅сm−1. Subjecting o-phenylenediamines 2с to the reaction with 3H-phenoxazin-3-one makes the simultaneous activation of two principle reaction pathways (SNH and Schiff base formation

• successfully under the conditions applied to the preparation of 14H-quinoxaline[2,3-b]phenoxazines 5. The reaction proceeds readily with o-mercaptoaniline to produce the benzo[5,6][1,4]oxazino[2,3-b]phenothiazine derivative 10c (Scheme 6). Electronic absorption spectra of the prepared 14Н-quinoxaline[2,3-b

• ]phenoxazines 5 and 6 (Table 2, Figures 5–7, and Figures S7–S11, Supporting Information File 1) exhibit broad and high-intensity absorption maxima in the range of 450–550 nm, which encompass the strongest emissive part of the solar spectrum. In contrast to nonfluorescent 6,8-di-tert-butyl-2-(arylamino)-3H

Discovery of unguisin J, a new cyclic peptide from Aspergillus heteromorphus CBS 117.55, and phylogeny-based bioinformatic analysis of UngA NRPS domains

• Sharmila Neupane,
• Marcelo Rodrigues de Amorim and
• Elizabeth Skellam

Beilstein J. Org. Chem. 2024, 20, 321–330, doi:10.3762/bjoc.20.32

• ]+ at m/z 773.4338, calculated for C41H57N8O7+, m/z 773.4345, Δ 0.9 ppm; [M + Na]+ at m/z 795.4162, calculated for C41H56N8O7Na+, m/z 795.4164, Δ 0.3 ppm) and NMR data analysis, corresponding to eighteen indices of hydrogen deficiency. Its UV spectrum exhibited absorption maxima at λmax 219 and 279 nm

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• stability. Conversely, selenepine 28c and selenepine Se-oxide 29c were quantitatively converted into the seco-HBC 31 by thermal activation at 200 °C for 5 min, as evidenced by UV–visible absorption and HPLC monitoring. SO-extrusion from thiepine S-oxide 29b was also successfully triggered in the solid state

• dinaphthooxanorcaradiene bisimide valence isomer obtained upon electron injection and not its neutral form, as shown by UV–vis absorption and DFT studies. The mechanism of the final release of oxygen still remains unclear. This example shows that a careful molecular design allows endowing chalcogen heteropines with

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• we analyzed by UV–vis spectroscopy. This peak was assigned as a bis(fulleroid) compound by comparing the spectra with the UV–vis absorption pattern exhibited by previously characterized C70 bis(fulleroids) reported by Murata et al. [43][48]. In addition, a minor peak at a retention time of 20 minutes