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Search for "polarity" in Full Text gives 410 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
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
- blue-shifted by 38 nm, and the shorter-wavelength emission peak (408 nm) was blue-shifted by 19 nm. These blue shifts are attributed to the hydrophobic environment in the PMMA matrix. In such low‐polarity surroundings, the excited state is less stabilized, resulting in a higher excited‐state energy and
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
- feature symmetrical alkylaminophenyl donor groups and a strong electron-withdrawing dicyanovinylene as an acceptor connected through vinyl groups as a π-bridge. These strongly π-conjugated organic dyes can absorb in the NIR region, and they showed sensitivity towards the polarity of solvents with
- planar structure, causing more delocalization of the π-electrons between donors and the acceptor (dicyanovinylene) group. The effect of solvent media was investigated with solvents of varying polarities, which showed a bathochromic shift in the absorption maxima with increasing solvent polarity. Dyes
- also showed significant color changes with increasing polarity. Color changes of 2a; from purple to blue, 2b; blue to green, and 2c; pale orange to pale pink (Figure 2d). Dyes do not show any significant emission. Chemosensor properties Cyanide selectivity study The dyes 2a–c could have the ability to
Reactivity umpolung of the cycloheptatriene core in hexa(methoxycarbonyl)cycloheptatriene
Beilstein J. Org. Chem. 2026, 22, 64–70, doi:10.3762/bjoc.22.2
- contraposes the expected and the unexpected in terms of polarity in either reactions or synthetic strategies (Figure 1). Most effective reactions within this concept involve the in situ generation of a species exhibiting reversed polarity and the original group is reestablished at later reaction stages [2
Tandem hydrothiocyanation/cyclization of CF3-iminopropargyl alcohols with NaSCN in the presence of AcOH
Beilstein J. Org. Chem. 2025, 21, 2694–2702, doi:10.3762/bjoc.21.207
- are easily separable by column chromatography due to their different polarity. Next, we investigated the substrate scope and limitations of the reaction using differently substituted iminopropargyl alcohols (Table 2). The presence of alkyl substituents in the hydroxy fragment was well tolerated
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
- available drugs [1]. These structures exhibit unique properties that influence pharmacokinetic and pharmacodynamic parameters, including lipophilicity, polarity, hydrogen-bonding capacity, and toxicological profiles [2][3][4]. Among them, five-membered multi-heterocyclic (FMMH) rings are privileged
- to 573 nm for compound 3n and from 479 to 524 nm for compound 4n. Therefore, the fluorescence emission spectra demonstrated a clear dependence on solvent polarity and the maximum emission wavelength λem. Thus, a red shift in the emission bands was observed in solvents with higher polarity, indicating
- solvents (MeOH, H2O) whereas lower values were recorded for chlorinated solvents (CH2Cl2, CHCl3). This trend matches with the Lippert–Mataga plots generated for these compounds to verify the relationship between the large values of Stokes shifts and the Reichardt polarity parameters. The graphs shown in
Efficient solid-phase synthesis and structural characterization of segetalins A–H, J and K
Beilstein J. Org. Chem. 2025, 21, 2612–2617, doi:10.3762/bjoc.21.202
- , demonstrating unequivocal structural identity with the natural isolates. Analytical HPLC confirmed the high purity (>95%) of all synthetic segetalins. However, experimental data for segetalin C revealed the existence of a multi-state conformational equilibrium in solution, which is dependent on solvent polarity
- –220 nm and a maximum below 200 nm. CD spectroscopy revealed that cyclic topology shifts characteristic peaks and stabilizes secondary structures through cooperative ring size/sequence/solvent effects [30]. TFE disrupts the hydrogen-bonding network of water, reduces solvent polarity, and enhances the
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
- simulations also suggest that the macrocycle of rotaxane 1-E tends to reside closer to the lipid–water interface, promoting more water accumulation than 1-Z, whose macrocycle positions deeper within the bilayer. This difference in localization likely arises from the substantial change in size and polarity of
The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions
Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184
- solvent polarity results in a decrease in rate constants. This phenomenon is attributed to the lower polarity of the transition state in comparison to that of the initial compounds [61]. Furthermore, these methods often require harsh reaction conditions, prolonged reaction times, and laborious
- space is shown in Figure 8a. The distribution of these selected solvents with other organic solvents in the 3D Hansen solubility space is determined by three Hansen solubility parameters (HSPs): dispersion (δD), polarity (δP), and hydrogen bonding (δH). As is well established, information about their
- potential hazard associated with their utilization as a solvent in the aforementioned reactions. For the solute component C,N-diphenylnitrone, the dispersion, polarity, and hydrogen bonding values for nitrone were determined as δD = 16.6, δP = 7.6 and δH = 8.7. Figure 8b clearly shows the position of the
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
- of the C–O bond “opens” the molecule, generating the corresponding merocyanine (Figure 2). The reverse photocyclization can occur upon exposure to visible light. Remarkably, the two isomers differ in their chemical and physical properties such as polarity, molecular volume, dipole moment
- photoisomerization to the merocyanine (open) form, FRET is activated – even when the macrocycle is relatively distant from the merocyanine – and becomes more pronounced as the donor approaches the acceptor. Moreover, this rotaxane exhibited tunable photoluminescence properties in response to solvent polarity, pH
Enantioselective radical chemistry: a bright future ahead
Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174
- polycyclic products in a highly diastereo- and enantioselective manner [45]. The polyene substrates were designed to facilitate a radical cyclization process, with alternating electron-poor and electron-rich olefins so as to enable polarity matching of the olefins and radical intermediates. With this design
- the type of radicals used can be overcome using photoredox catalysis. Synergistic photoredox and other forms of catalysis (using chiral Lewis acids, chiral Brønsted acids, H-bonding compounds, polarity reversal catalysts, etc.) expanded the scope of radical traps used and introduced alternate ways of
Pathway economy in cyclization of 1,n-enynes
Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173
- and co-workers achieved an innovative gold-catalyzed cascade cycloisomerization of 3-allyloxy-1,6-diynes to access cyclopropane- and cyclobutane-fused benzofurans/chromanols (Scheme 5) [12]. In this study, solvent polarity and trace water were identified as key parameters governing the reaction
- modulating reaction parameters – including solvent polarity, catalyst architecture, ligand electronic effects, and substrate strain effects – chemists can achieve unprecedented control over reaction pathways. This approach enables divergent access to complex molecular architectures from a unified substrate
Bioinspired total syntheses of natural products: a personal adventure
Beilstein J. Org. Chem. 2025, 21, 2048–2061, doi:10.3762/bjoc.21.160
- was then treated with AcOH to afford the putative iminium cation to be chemoselectively reduced with NaBH3CN to ultimately reach the amine functionality. Through this protocol, the amine product was obtained, but it could not be isolated from silica gel for its high polarity. Thus, the extracted crude
Photoswitches beyond azobenzene: a beginner’s guide
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
- tautomerism is an intermolecular process that depends not only on the choice of aryl rings and substituents but also on concentration, solvent polarity, and the presence of proton sources [5][15]. In conclusion, the choice of aryl rings, substituents, and substitution position are all crucial to determine the
- soluble in water. For C- and S-diazocine, the absorption band separation of the two isomers is lower in polar solvents, resulting in worse PSS. In particular, for the S-diazocine it was found that the E-chair conformer was bathochromically shifted with increasing polarity of the solvent until completely
- side and electron-donating substituents on the other side giving the best performance (Figure 16, left). These peculiar compounds also showed increased stability and red-shift with increasing solvent polarity [87]. Oxidation of the sulphur atom to sulphoxide 69 introduces a sulphur-based stereocentre
Thermodynamics and polarity-driven properties of fluorinated cyclopropanes
Beilstein J. Org. Chem. 2025, 21, 1742–1747, doi:10.3762/bjoc.21.137
- electrostatically complementary negative and positive faces. These interactions are mediated through electrostatic hydrogen bonds. This "Janus-like" polarity also facilitates interactions with ions, particularly sodium and chloride. These findings contribute valuable insights for the rational design of drugs and
- advanced materials, particularly those whose properties rely on the polarity and spatial arrangement of C–F bonds within a cyclopropane framework. Keywords: cyclopropane; fluorination; polarity; theoretical calculations; Introduction Cyclopropane, the smallest cycloalkane, has a rigid structure that
- polarity, with these effects varying based on the amount, position, and orientation of the fluorine substituents [7][8]. Mondal and colleagues have extensively reviewed additional properties of fluorinated cyclopropanes, including the conformational behavior of substituents attached to a fluorinated
Approaches to stereoselective 1,1'-glycosylation
Beilstein J. Org. Chem. 2025, 21, 1700–1718, doi:10.3762/bjoc.21.133
- of similar polarity (Scheme 10). Replacing the 2N-Troc protecting group with a 2N-Fmoc group in the imidate donor 121 led to formation of fully desymmetrized βGlcN(1↔1′)βGlcN disaccharide 122 with an improved isolated yield of 65% [95]. While the “armed” donors 79 and 121 were sufficiently reactive
Thermodynamic equilibrium between locally excited and charge transfer states in perylene–phenothiazine dyads
Beilstein J. Org. Chem. 2025, 21, 1577–1586, doi:10.3762/bjoc.21.121
- -carborane exhibit such behavior, where LE and CT states dynamically interconvert depending on solvent polarity and temperature [10][11][12]. When the interconversion is faster than radiative decay, the two states can reach thermodynamic equilibrium, and their relative populations are determined by the
- intensity as the solvent polarity increased, which are typical features of CT states (Figure S22 in Supporting Information File 1). The emission intensity of the CT band was almost comparable to that of the LE band of the Pe moiety in Pe–Ph–PTZ(TPA)2, whereas the emission intensity of the CT band is larger
Azobenzene protonation as a tool for temperature sensing
Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115
- and solvent polarity, we demonstrate that the degree of protonation, and thus solution color, is highly temperature-dependent, changing from pale yellow to deep red as temperature decreases. We also present mechanistic insights and compare our experimental findings with computational results. Results
- strong acidity of MSA, moderate polarity of DCE, and the electron-donating substituents of 3, only 76 equivalents of acid (3.08 mM) is needed for nearly full protonation as indicated by the almost complete disappearance of the absorption peak at 360 nm. Similar data for compounds 1 and 2 in MSA/DCE
Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
Beilstein J. Org. Chem. 2025, 21, 1496–1507, doi:10.3762/bjoc.21.112
- as electron or hole-induced switching. Depending on the polarity of the bias, either an electron is injected (at positive sample bias) or a hole (at negative sample bias). This may be directly compared to the electron or hole-catalyzed isomerization of molecules in solution [40][41][42]. Generally
Wittig reaction of cyclobisbiphenylenecarbonyl
Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107
- byproduct and exhibited similar polarity as compound 5. The obtained compounds 3, 4, and 5 were identified using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) (see Supporting Information File 1) as well as single crystal X-ray diffraction analysis (vide infra). Furthermore, the
Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications
Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106
- displays red-shifted emission and prolonged fluorescence lifetimes as solvent polarity increases, indicating enhanced excited-state stabilization. Collectively, these studies offer valuable strategies for stabilizing long π-extended helicenes and finely tuning their chiroptical and emissive properties
- across the visible spectrum, with both emission intensity and chiroptical properties varying in response to solvent polarity. Concurrently, Würthner’s group developed two naphthalimide-annulated [n]helicenes, compounds 56a and 56b (n = 5, 6), via a concise two-step synthetic route that afforded excellent
Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds
Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105
- reasons are different. While in acetonitrile this is the effect of the increased polarity of the solvent, leading to stabilization of the more polar keto tautomers, in the non-polar chloroform it is caused by its proton-donative nature (formation of a stabilizing intermolecular hydrogen bonding with the C
- =O group of the keto tautomers [51][56]). The effects of acetone, methanol and DMSO, as seen, are based only on the increased (comparing to toluene) dielectric constant of the solvent, stabilizing in different extent the more polar KE and KK. The further increase of the polarity of the environment by
Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles
Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104
- , the atom N(2) deviates from the RMS plane S(1)C(3)C(4)C(5) by 0.461 Å. The atom of the N(1) morpholine fragment has a planar configuration with significant asymmetry in the lengths of C–N bonds. Due to the electron-acceptor effects of substituents, the C(3)‒H bond exhibits significant polarity and is
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- (Figure 2) [10][11][12]. As for the analogy to carbonyls, oxetanes display comparable polarity, spatial arrangement of the oxygen lone pairs and hydrogen-bond-accepting ability. In addition, they possess one major advantage and that is greater metabolic stability: while carbonyl groups are susceptible to
- methyls with an oxygen atom effectively eliminates its lipophilic character and reduces susceptibility to metabolic attack, while practically maintaining the molar volume. Because controlling polarity and metabolic stability is a major issue in medicinal chemistry, 3-substituted oxetanes have eventually
Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer
Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100
- positive and negative charges of two species can be stabilized by the electronic effects, these species are considered to be polarity matched during the HAT process. Conversely, when there is a polarity mismatch, the HAT process is likely to be impeded (Figure 2a). C–H bonds predominantly prefer to be
- nucleophilic, which smoothly facilitates the HAT process with amidyl radical. This effect is also called a polarity match [31][32][33][34][35][36][37][38][39]. 3) Considering the electronic effect, modifying the substituent of the N atom could tune the property of HAT capability (Figure 2b) [40][41][42][43
- structurally diversified target molecules 65–68 under optimized reaction conditions. In these cases, the high polarity of the radical intermediates of CF3CH2OH and 4-methylbenzonitrile, combined with the poor solubility of adamantane, may explain the possible reasons behind the reaction process [91]. Amidyl
Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers
Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95
- chromatography on silica gel because of their low polarity and poor solubility in n-hexane. On the other hand, nitration of [3.3.3] gave solely the six-fold nitrated product due to low solubility of the starting material [46]. The current reaction is the first practical method for the selective
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