Enhanced target cell specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

• Roslyn M. Ray,
• Anders Højgaard Hansen,
• Maria Taskova,
• Bernhard Jandl,
• Jonas Hansen,
• Citra Soemardy,
• Kevin V. Morris and
• Kira Astakhova

Beilstein J. Org. Chem. 2021, 17, 891–907, doi:10.3762/bjoc.17.75

• average sizes of 57.3 nm and 91.9 nm, respectively, as well as a more negative ZP (−11 mV and −9.4 mV, respectively, Table 2). These ZP values indicate that complexation leads from a neutral to anionic LNP product [39], a property that typically confers with low to no cytotoxicity in vivo [40]. Further

• complexation with cluster of differentiation 4 (CD4) and CCR5 or C-X-C motif chemokine receptor 4 (CXCR4) host cell surface receptors [35]. As such, gp160 expression on the host cell surface receptor may not be as adept at facilitating cell entry via receptor-mediated endocytosis. Although in 2009, Zhou et al

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• biologically active molecules that already find practical use. It has been found that complexation improves the transportation of a drug and prolongs its effect, and a synergistic effect is observed in some cases [36]. The situation with covalent binding in fullerene–drug conjugates is different. C60 is an

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• properties of selected aminophthalazinones towards Cu(II) ions were investigated and the participation of the nitrogen atoms in the complexation of the metal ion was shown. A biological screening of the potential cytotoxicity of selected synthesized compounds on HT-29 and PC-3 cell lines, as well as on the L

• observed. Instead, the partial demethylation of the amine occurred. As a result, a mixture of the products 6c and 6d (molar ratio 6c/6d = 1:4) was obtained. With the increase in the amount of palladium (15 mol %) the phthalazin-1(2H)-one derivative 6d was obtained as the main product (70%). Complexation

• . Proposed catalytic cycles for the amination of 4-bromophthalazinones of type 3 (Phthal: phthalazinone, PhthalBr: 4-bromophthalazinone, PhthalNR1R2: 4-aminophthalazinone). The phthalazinone derivatives that were used to test the complexation of Cu(II) ions. Structure of complex 17. Molecular structure of

Metal-free visible-light-enabled vicinal trifluoromethyl dithiolation of unactivated alkenes

• Xiaojuan Li,
• Qiang Zhang,
• Weigang Zhang,
• Jinzhu Ma,
• Yi Wang and
• Yi Pan

Beilstein J. Org. Chem. 2021, 17, 551–557, doi:10.3762/bjoc.17.49

• complexation of the intermediate I with K2HPO4 provides the intermediate II. Then, 4CzIPN* (4CzIPN+/4CzIPN*: E1/2red = −1.04 V vs SCE) [51] reduces the intermediate II to generate a phthalimide anion (Phth− [50]) and a trifluoromethylthio radical under irradiation. The SCF3 radical readily reacts with the

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• -aminide ligand in a manganese complex [29], being the only structurally characterized complex with a neutral 1,3-dialkyltetrazolium-5-aminide. Therefore, it is of interest to compare the structural data for this compound with those obtained for compound 8a to find the influence of the complexation on the

• the exocyclic C5–N5 bond is longer compared to aminide 8a. One can expect that these structural differences are due to the complexation. It should be noted that the bond lengths of the tetrazole ring N11/C15 in compound 11a are usual for 1- and 1,5-substituted tetrazoles. The compounds 8a, 10, and 11a

• their complexation. In salt 9, the bromide ions are held in the crystal structure by hydrogen bonds N15–H15···Br1b [D···A = 3.2774(17) Å, D–H···A = 142°; symmetry code: (b) –x + y + 1/3, −x + 2/3, z + 2/3] and N25–H25···Br2 (D···A = 3.2654(17) Å, D–H···A = 144°). There are also intramolecular hydrogen

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• structural rigidity caused by supramolecular host–guest complexation, ii) that a restricted space, size, and volume could lead to three-dimensional translation (rotation, vibration, and translation) of the guests within the host cavities, and iii) the dynamic properties of the guest within the supramolecular

• , Yagi, et al. reported that the visible-light-driven hydrogen evolution of the supramolecular system could be achieved by the host–guest complexation between the cobaloxime CoPyS and γ-CD (Figure 10) [30]. Upon visible-light irradiation, the CoPyS:γ-CD 1:1 complex exhibited an enhanced photocatalytic H2

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• studies of NO2-C9∙∙∙F4St. The photographs of the solid components as well as the formed complex under UV light irradiation (λex = 365 nm) reveal the change in fluorescent intensity upon complexation (a); fluorescence intensity plot as a function of the temperature upon heating from room temperature to 110

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• -unsaturated enone to afford conidiogenone B (171) in 32% yield upon treatment with RhCl3 in microwave. The reaction mechanism of Danheiser’s [3 + 2] annulation is shown according to the Danheiser’s proposal [74] (Scheme 13C, inset). Initial complexation of the α,β-unsaturated ketone 167 and titanium

Chiral anion recognition using calix[4]arene-based ureido receptors in a 1,3-alternate conformation

• Tereza Horáčková,
• Jan Budka,
• Vaclav Eigner,
• Wen-Sheng Chung,
• Petra Cuřínová and
• Pavel Lhoták

Beilstein J. Org. Chem. 2020, 16, 2999–3007, doi:10.3762/bjoc.16.249

• for N-acetyl-ʟ-phenylalaninate. The structures of some receptors were confirmed by single crystal X-ray analysis. Keywords: anion recognition; calixarene; chiral receptor; complexation; enantiodiscrimination; Introduction The recognition and complexation of anions has become undoubtedly one of the

• highly sophisticated molecules, including anionic receptors [27][28][29][30][31][32][33][34][35][36][37][38][39]. During our ongoing research on anion complexation, we have reported various calix[4]arene receptors based mainly on amide, urea, or thiourea groups [40][41], some of which are available in

• different conformations. Although the overwhelming majority of calixarene-based receptors makes use of the cone conformer A (Figure 1), the corresponding diureidocalix[4]arenes in the 1,3-alternate conformation B showed [42][43] surprisingly good complexation abilities towards selected anions. Especially

Construction of pillar[4]arene[1]quinone–1,10-dibromodecane pseudorotaxanes in solution and in the solid state

• Xinru Sheng,
• Errui Li and
• Feihe Huang

Beilstein J. Org. Chem. 2020, 16, 2954–2959, doi:10.3762/bjoc.16.245

• 450001, P. R. China 10.3762/bjoc.16.245 Abstract We report novel pseudorotaxanes based on the complexation between pillar[4]arene[1]quinone and 1,10-dibromodecane. The complexation is found to have a 1:1 host–guest complexation stoichiometry in chloroform but a 2:1 host–guest complexation stoichiometry

• reports [44][45]. We found that H and G can be used to build a [3]pseudorotaxane in the solid state but a [2]pseudorotaxane in solution. Results and Discussion Host–guest complexation in the solid state Cocrystals of H and G were obtained by slow evaporation of the solution in methanol. The X-ray

• the hydrogen atoms on the ethoxy groups. It is worth mentioning that we did not find any interaction of the benzoquinone subunit of the host with the guest molecule. Host–guest complexation in solution In order to further study the host–guest binding properties of H and G, we explored the complexation

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• -benzoxazole [13] or different other acetohydrazines [14], complexation of phenothiazinyl-chalcone using diiron nonacarbonyl [15], and regioselective oxidation [16]. α-Aminonitriles are versatile synthetic intermediates that are readily obtainable by a Strecker reaction involving the addition of a cyanide

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

• (CBS) [6][7][8][9]. The GCP takes part selectively and efficiently in the complexation of carboxylates based on the electrostatic interaction between the positively charged CBS and the negatively charged carboxylate in the combination with hydrogen bonding, enabling molecular recognition even in the

• strengths. Various spectroscopic techniques can be employed for monitoring these changes. For example, electronic absorption or fluorescence spectroscopy can probe the spectral differences due to the complexation of the supramolecular ligand with a peptide or protein. However, electronic spectroscopies

• receptor. The vibrational assignment of these modes is important for the binding study of GCI receptors because we hypothesize that they are all involved in the complexation with carboxylates. Finally, we employed UVRR spectroscopy at 244 nm excitation to observe the binding events of GCI-based receptors

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• hexacyclene, a strong complexation agent for zinc(II) ions, the communication was reversed and the supramolecular assemblies were disassembled to regain the initial state of the system (SelfSORT-I). The use of multiple chemical inputs in combination with translocation is the key to remotely control the

• ), the silver(I) ions were tightly captured within the cavity of the triangular nanoswitch 35 (“catch”) while the luminophore 36 was left uncoordinated exhibiting emission at 554 nm (Figure 13). Due to the firm complexation of the silver(I) ions in [Ag(35)]+ any catalysis was switched OFF. Upon the

• hydrogen-bonded octameric and tetrameric tubes. (c) A representation of the complex mixture after combining the monomers 5 and 6 in CDCl3. (d) The partial separation of the mixture upon the selective C60 complexation by monomer 5. The guest-induced rearrangement results in an incomplete self-sorted mixture

Synthesis and investigation of quadruplex-DNA-binding, 9-O-substituted berberine derivatives

• Jonas Becher,
• Daria V. Berdnikova,
• Heiko Ihmels and
• Christopher Stremmel

Beilstein J. Org. Chem. 2020, 16, 2795–2806, doi:10.3762/bjoc.16.230

• the two dyes. With this assay, the thermodynamic stabilization or destabilization of the quadruplex structure upon the complexation of the ligand is indicated by the shift of the melting temperature ΔTm. The analysis revealed an increasing stabilization of the quadruplex F21T toward dissociation with

• the ligands 4a–e on the addition of G4-DNA is the result of a sufficiently tight complexation. As this fluorescence light-up effect depends significantly on the length of the linker chain n, it is also concluded that the ligands with the strongest effect, i.e., 4c and 4d (n = 4 and 5), have a more

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• converting the free DPA residues on the nanoparticle surface into the corresponding zinc(II) complexes. To ensure the successful metal complexation and to determine the minimum amount of zinc(II) nitrate required for a complete conversion, we followed the 1H NMR spectroscopic effects of the addition of a 0.1

• , this signal became smaller and two doublets appeared at lower ppm values. Once the concentration of the zinc salt exceeded a certain value, only these doublets were still visible. In addition, zinc complexation also affected the aromatic signals of the DPA ligands. The spectral changes observed in the

• spectra confirmed that zinc complexation had occurred under the chosen conditions. The change of the multiplicity of the methylene signal accounted for the rigidification of the DPA moiety during metal binding, which rendered the corresponding protons diastereotopic. The rate of metal exchange was

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• , maximized π–π-interactions with the axle because of the 84° torsional angle between the resorcinol and the NDI unit. Consequently, the complexation of NDIC8 is less enthalpically favored than that of TTFC8. However, the more rigid structure of NDIC8 also leads to a lower degree of conformational fixation in

• hand, additional π–π-interactions of the phenyl ring in A1·PF6 to the crown ether aromatic rings favor the complex formation. On the other hand, the flexibility of the alkyl substituent in A2·PF6 is diminished upon complexation, inducing a larger entropic penalty visible in the overall more negative

• ). These results suggest that both ammonium axles form a similar type of equilibrium with NDIC7, where the protonation of the tertiary amine and the complexation in a nonthreaded complex might contribute. When using BArF24− as the counterion for A1, the binding energies increase by 6–8 kJ/mol, which

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

• Ka = (2.20 ± 0.16) × 105 M−1, respectively. The binding affinity between TBTQ-(OG)6 and C60 was further verified by Raman spectroscopy. The geometry of the complex of TBTQ-(OG)6 with C60 deduced from DFT calculations indicates that the driving force of the complexation is mainly due to the

• C60 and C70 [1][2][3][4][5]. It is generally accepted that good complexation of fullerenes requires host molecules with bowl or basket-like shapes, such as calixarenes [6], corannulenes [7][8][9][10], cyclodextrins [11][12][13], cyclotriveratrylenes [14][15][16], and similar macrocycles [17][18][19

• attention for potential applications in host–guest recognition, such as gas storage and cationic complexation [31][32][33]. In the past years, the recognition of the biological and pharmaceutical relevance of fullerenes, such as their photodynamic activity, phototoxicity, HIV-1 protease inhibitor ability

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• indicating the presence of Pd(II) (Figure 3a). In contrast, Pd primarily exists as Pd(II) on PdNP@ChsNC (Figure 3b), which could be attributed to three possible reasons: 1) the presence of PdCl2, 2) the oxidation of Pd NPs into PdO, and 3) the complexation of Pd(II) by ChsNCs. To address the first point, a

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• complexation to the Lewis acid in RCA reactions, an auxiliary (Z) is required; this auxiliary can be easily removed and recovered. Shibasaki and Kumagai very recently developed a similar reaction using a copper Lewis acid catalyst and a different auxiliary containing amide 282 with α-silyl amines 277 to

Hierarchically assembled helicates as reaction platform – from stoichiometric Diels–Alder reactions to enamine catalysis

• David Van Craen,
• Jenny Begall,
• Johannes Großkurth,
• Leonard Himmel,
• Oliver Linnenberg,
• Elisabeth Isaak and
• Markus Albrecht

Beilstein J. Org. Chem. 2020, 16, 2338–2345, doi:10.3762/bjoc.16.195

• ]. Catechol ligands L-H2 with an ester functionality in the 3-position were prepared via conversion of the acid chloride of 2,3-dihydroxybenzoic acid to the corresponding esters. These ligands underwent a complexation with titanoyl(IV) bisacetylacetonate and lithium carbonate initially forming a mononuclear

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• transfer systems, cation–π complexation, electron conductivity, optical properties and so on. Keeping the importance of this beautiful scaffold in mind, we compiled all the synthetic routes available for the construction of sumanene and its heteroatom derivatives including Mehta’s first unsuccessful effort

• /H2O solution, but they received unsuccessful results may be due to its unstable behavior. Pleasingly, they got the fruitful result by converting 120 into phenylboronate ester 121 as can be noted from an inspection of Scheme 29. 2.3 Complexation of sumanene and its derivatives Since coordination is one

• , Yakiyama, Hasegawa, and Sakurai reported two sumanene-based porous coordination networks 127 (spherical tetramer units) and 128 (belt-like trimer units) through complexation of the hexapyridylsumanene 95d with Cd(NO3)2·4H2O as well as Zn(NO3)2·6H2O, (Scheme 33) [65]. The C3-symmetric sumanene derivative

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• complexation of the PSCat with Selectfluor® and TTET. The practicality of this photosensitized monofluorination was demonstrated using ethylbenzene on gram scale (Scheme 8) [135]. Ethylbenzene (2.12 g) was monofluorinated to give the desired fluorinated product (2.11 g) in 85% isolated yield, almost identical

• ® radical cation is regenerated here upon FAT, the authors considered the candidacy of the Selectfluor® radical cation as a chain carrier. However, the quantum yield of the reaction was found to be only Φ = 0.13, strongly evidencing against a radical chain mechanism. The complexation of Selectfluor® with

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• enthalpy (ΔH [kcal/mol]) and positive entropy (ΔS [cal/mol/K]) values, pointing out that the complexation processes are enthalpy-driven and characterised by the same type of binding mode, i.e., intercalation [17][44]. The relatively large entropy contribution might be attributed to the displacement of

• arrangement of the NDI dye to the base pairs (red arrow in Figure 8, for 3b). The complexation with poly(dA-dT)2 (Supporting Information File 1, Figure S27) resulted in a negative ICD band (505 nm) only for compound 5, whereas 3a and 3b did not show any measurable ICD signal, likely due to the intercalation

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• aqueous conditions to prevent complexation of the reagent and the starting material. Of the Lewis acids used, stannic chloride proved to be the most effective oxidant for dimerization (Table 1). However, the hypervalent iodine reagents PIFA and PIDA gave better results overall, affording dimer 18 in 63