Binding of group 15 and group 16 oxides by a concave host containing an isophthalamide unit

• Jens Eckelmann,
• Vittorio Saggiomo,
• Svenja Fischmann and
• Ulrich Lüning

Beilstein J. Org. Chem. 2012, 8, 11–17, doi:10.3762/bjoc.8.2

• . The syn/syn conformation can be stabilized by using isophthalamide derivatives capable of intramolecular hydrogen bonding to the CO part of the amide groups [10][11], or by other means of bridging [12]. Due to the preorganization of such molecules, the binding constant for chloride is impressively

Supramolecular FRET photocyclodimerization of anthracenecarboxylate with naphthalene-capped γ-cyclodextrin

• Qian Wang,
• Cheng Yang,
• Gaku Fukuhara,
• Tadashi Mori,
• Yu Liu and
• Yoshihisa Inoue

Beilstein J. Org. Chem. 2011, 7, 290–297, doi:10.3762/bjoc.7.38

• = 182 M−1 and K2 = 56700 M−1) [12], the first binding constant was enhanced by a factor of 3.5–5.8 by introducing the naphthalene moiety, whilst the second binding constant was reduced by a factor of 2.5–3.0, thus making the overall binding constant (K1K2) approximately twice as high. It is known that

Fluorometric recognition of both dihydrogen phosphate and iodide by a new flexible anthracene linked benzimidazolium-based receptor

• Kumaresh Ghosh and
• Debasis Kar

Beilstein J. Org. Chem. 2011, 7, 254–264, doi:10.3762/bjoc.7.34

• showed 1:1 binding (Supporting Information File 1). However, the selectivity of 1 towards the anions studied was established by determining the binding constant values from fluorescence titration data (Table 1) [39]. As can be seen from Table 1, the receptor 1 shows a marginal selectivity for H2PO4−. The

• the polar C+–H bond of benzimidazolium motif and reduces the possibility of host–guest interactions [46]. This is clearly reflected in the binding constant values in Table 1. Due to the presence of a minimum amount of CH3CN in CHCl3 the binding constant values for the selected anions are greater in

• of the study due to insolubility in the NMR concentration range and this was one reason for not determining the binding constant values by the NMR method. However, both the amide and benzimidazolium protons (0.51 ppm) were found to move downfield and thereby supported our binding proposition as

Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt

• Kumaresh Ghosh,
• Tanmay Sarkar and
• Asoke P. Chattopadhyay

Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139

• and guest used at which the titration experiments are monitored. Analysis of the emission data provided the association constants (Ka), reported in Table 2 [33]. For determining binding constant values for L-N-acetylvaline and L-N-acetylalanine salts, we considered the emission data up to the addition

• of 13 equivalents of the guests added, since in the presence of large excess of such guests complex stoichiometries were noted. From Table 2 it can be seen that receptor 1 exhibits higher binding constant values for L-N-acetylvaline in the series. At this moment, we believe that it is due to

• structural aspects as well as to the hydrogen bonding capacity of the valine salt. Furthermore, to establish the hydrogen bonding influence of the acylamino and hydroxy groups of the amino and hydroxy acids respectively, we determined the binding constant for the acetate anion. This was found to be slightly

Anion receptors containing thiazine-1,1-dioxide heterocycles as hydrogen bond donors

• Hong-Bo Wang,
• James A. Wisner and
• Michael C. Jennings

Beilstein J. Org. Chem. 2010, 6, No. 50, doi:10.3762/bjoc.6.50

• 3 with acetate had a binding constant that was too large to be reliably fit by this method. The titration results are summarized in Table 1. Receptor 1 exhibits a clear preference for a chloride anion guest over the other anions tested. Chloride is likely an excellent steric match to the cleft

• acetate and dihydrogen phosphate over all of the other anions investigated in this solvent. The binding constant for chloride is reduced by an order of magnitude but is still preferred over bromide even though the affinity of 3 for the latter guest has approximately doubled in comparison to receptor 1. No

Anthracene coupled adenine for the selective sensing of copper ions

• Kumaresh Ghosh and
• Tanushree Sen

Beilstein J. Org. Chem. 2010, 6, No. 44, doi:10.3762/bjoc.6.44

• group on the amine functionality. The binding constant curves are given in Figure 8 and the linear nature of the curves establishes 1:1 binding model during the interaction process. The ground state interaction properties of 1 and 2 were also investigated with the same metal ions in CH3CN containing 0.1

• ) Binding constant curve for 1 with Cu2+ ion; b) binding constant curve for 2 with Cu2+ ion. a) Absorption spectra of receptor 1 (c = 5.09 × 10−5 M) upon gradual addition of Cu2+ ion (c = 1.4 × 10−3 M) in CH3CN containing 0.02% DMSO; b) absorption spectra of receptor 2 (c = 1.48 × 10−5 M) upon gradual

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• crown ethers size and constitution on the binding constant in methanol. The data were determined using an ion-selective electrode. Depending on the ratio of the crown ether ring size [103] and the diameter of the cation complex, different 1:1 topologies are observed reflecting differently strong co

• ). Enantiomeric recognition of chiral primary ammonium perchlorate salts was investigated with analogous chiral mono aza-18-crown-6 derivatives such as 27 [159]. For the isobutyl compound (27, R = iBu), the host exhibited the highest binding constant and the best enantiomeric selectivity ability towards 1

• binding constant of 7.8 × 103 M−1 was found for the complex of phenyl substituted (R,R)-30 with the R-enantiomer of the guest. Chiral side arms derived from phenethylamine attached to diaza-18-crown-6 ethers 31 (Figure 17) effectively enable the molecular recognition of aromatic amino acid potassium and

Synthesis of indolo[3,2-b]carbazole-based new colorimetric receptor for anions: A unique color change for fluoride ions

• Ajit Kumar Mahapatra,
• Giridhari Hazra and
• Prithidipa Sahoo

Beilstein J. Org. Chem. 2010, 6, No. 12, doi:10.3762/bjoc.6.12

• anions were dissolved in UV-grade acetonitrile and water (4:1 v/v). The corresponding absorbance values for receptor 1 were noted during titration and used for the determination of binding constant values. Binding constants were determined by using the expression A0/A − A0 = [εM/(εM − εC)](Ka−1 Cg−1 + 1

• − anions). The measured absorbance A0/A − A0 as a function of the inverse of the guest anion concentration fits a linear relationship, indicating a 1:2 complexation of the receptor and anions. The ratio of the intercepts to the slope was used to determine the binding constant Ka. Geometric optimization of

• ). Fluorescence change of receptor 1 (c = 4.475 × 10−5 M) upon gradual addition of [Bu4N]+F− (left side) and [Bu4N]+AcO− (right side) in CH3CN/H2O (4:1 v/v) (c = 4.475 × 10−5 M) (λmax = 443 nm). Binding constant calculation curves for receptor 1 vs F−, Cl−, Br−, I−, AcO−, HSO4−, and H2PO4− (left side

Self-association of an indole based guanidinium-carboxylate-zwitterion: formation of stable dimers in solution and the solid state

• Carolin Rether,
• Wilhelm Sicking,
• Roland Boese and
• Carsten Schmuck

Beilstein J. Org. Chem. 2010, 6, No. 3, doi:10.3762/bjoc.6.3

• stability of these dimers was determined by an NMR dilution experiment. To obtain the binding constant for the dimerisation, we studied the concentration dependence of the 1H NMR spectrum of 2 in a concentration range from 0.25 to 100 mM in [D6]DMSO. The 1H NMR shifts are concentration-dependent as expected

Quinoline based receptor in fluorometric discrimination of carboxylic acids

• Kumaresh Ghosh,
• Suman Adhikari,
• Asoke P. Chattopadhyay and
• Purnendu Roy Chowdhury

Beilstein J. Org. Chem. 2008, 4, No. 52, doi:10.3762/bjoc.4.52

• dicarboxylic acids from aliphatic dicarboxylic acids and even long chain aliphatic dicarboxylic acids from short chain aliphatic dicarboxylic acids. The receptor 1 is found to be selective for citric acid with a strong excimer emission in CHCl3. On the contrary, the receptor 2 exhibited less binding constant

• lower concentration led to a more accurate determination of the values of the association constants for the acids (Table 1) [19]. Citric acid, a tricarboxylic acid with more hydrogen bonding groups, shows a higher binding constant than D-(−)-gluconic and D-(−)-tartaric acids. D-(−)-Gluconic acid with

• change in absorption of the receptor was noted after each addition. The binding constant values determined by this method are found to be less (Table 1) due to the presence of DMSO, a competitive hydrogen-bonding partner which reduces the binding affinity. Interestingly, as we move from receptor 1 to