(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• phosphate were obtained from NMR titration experiments for both series of glucooligomers. The binding affinity of the thiourea and guanidine oligomers was stronger than in the case of the urea analogues. Stimulated by the interesting supramolecular properties and applications of cyclodextrins (CDs), a range

• expression in living cells has required the development of modified oligonucleotides as potential therapeutic agents. A key goal in the design of such agents include increasing binding affinity while maintaining sequence specificity, resistance to degradation by nucleases and improved membrane permeability

Templated versus non-templated synthesis of benzo-21-crown-7 and the influence of substituents on its complexing properties

• Wei Jiang and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2010, 6, No. 14, doi:10.3762/bjoc.6.14

• more efficient than the intramolecular macrocyclization without template. Pseudorotaxanes form with secondary ammonium ions bearing at least one alkyl chain narrow enough to slip into the crown ether. Substitution on benzo-21-crown-7 or on the secondary ammonium axle alters the binding affinity and

• of guest from secondary dibenzylammonium hexafluorophosphate (360 M−1, 1.0 mM, in acetone-d6) [31] to the anthracenyl methyl-substituted analogue 5-H•PF6 (496 M−1, 1.0 mM, in acetone-d6) [26] increases the binding affinity with DB24C8, which is mainly attributed to stronger π-π stacking interactions

• template during the synthesis of C7 from catechol and 3 results in a much more easily achievable separation of uncomplexed C7. We speculate that the lower solubility of this salt in organic solvent helps to separate the crown ether from the salt during the extraction. The effect of substituents on binding

Size selective recognition of small esters by a negative allosteric hemicarcerand

• Holger Staats and
• Arne Lützen

Beilstein J. Org. Chem. 2010, 6, No. 10, doi:10.3762/bjoc.6.10

• found to have a weak affinity for simple esters in a size selective manner in the absence of an effector whereas it does not show any binding affinity when it is coordinated to a tris(carbonyl)rhenium chloride fragment – thus showing negative cooperative allosteric behaviour. Results and Discussion

• rather observed an averaged signal very close to the one of the free guest due to the large excess of the free substrate. Despite the large excess of the free guest this also hints at a rather low binding affinity of 2 towards the esters as expected for the reasons given above. Addition of the larger

Recognition properties of receptors consisting of imidazole and indole recognition units towards carbohydrates

• Monika Mazik and
• André Hartmann

Beilstein J. Org. Chem. 2010, 6, No. 9, doi:10.3762/bjoc.6.9

• and interesting binding preferences of these acyclic compounds. Compared to the previously described acyclic receptors, compounds 4 and 5 showed significantly increased binding affinity towards β-galactoside. Both receptors display high β- vs. α-anomer binding preferences in the recognition of

• of DMSO-d6 a substantial fall in the binding affinity was observed. Studies that were performed with 4 and 11 in 5% DMSO-d6 in CDCl3 revealed K11 = 12000 M–1 and K21 = 3000 M–1, those performed with 5 and 11 indicated the formation of complexes with 1:1 receptor–sugar stoichiometry with K11 = 42000 M

• powerful monosaccharide receptor than the indole-based compound 5 and the previously described receptors 1–3. Compared to 1 and 2, incorporating only one imidazole or indole recognition unit, receptor 5 showed increased affinity to β-galactoside but decreased affinity to β-glucoside. The binding affinity

Synthesis and binding studies of two new macrocyclic receptors for the stereoselective recognition of dipeptides

• Ana Maria Castilla,
• M. Morgan Conn and
• Pablo Ballester

Beilstein J. Org. Chem. 2010, 6, No. 5, doi:10.3762/bjoc.6.5

• modulation of their binding affinity as a function of the hydrogen-bonding pattern exhibited by the target molecule. We also describe the levels of stereoselectivity displayed by these receptors in the recognition of the diastereoisomers and enantioisomers of Ala-Ala dipeptide. We explain the differences

• structures to examine the molecular recognition properties of receptors 1, 2, 15, and 17 (Figure 8). We selected a series of diamides to evaluate the effect that the hydrogen-bonding pattern produces in the binding affinity. We also investigated the molecular recognition properties of the receptor series

• clashes detected between the dipeptide side chains and the benzophenone linking units should significantly reduce the binding affinity of the cyclic receptors for this substrate or even favor the formation of an alternative complex with exo-geometry. Unexpectedly, the stability constant values that we

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

• 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

8-epi-Salvinorin B: crystal structure and affinity at the κ opioid receptor

• Thomas A. Munro,
• Katharine K. Duncan,
• Richard J. Staples,
• Wei Xu,
• Lee-Yuan Liu-Chen,
• Cécile Béguin,
• William A. Carlezon Jr. and
• Bruce M. Cohen

Beilstein J. Org. Chem. 2007, 3, No. 1, doi:10.1186/1860-5397-3-1

• ) itself, whose binding affinity (Ki = 43 nM) was reportedly greater than that of the natural epimer 2a (111 nM).[8] To explore this anomaly, we submitted a new sample of 2b for in vitro testing at the KOR. Binding affinity, potency and efficacy were determined as previously described (Table 1).[26] The

• binding affinity of 2b (Ki = 304 nM) was lower than those previously reported for salvinorin B (2a) under the same conditions (66, 111 or 155 nM).[7][8][27] An early report that 2a was inactive employed a different radiolabeled ligand, [3H]bremazocine.[28] Subsequent testing with [3H]diprenorphine by the

• ), but the 8-epimer 4b showed high affinity at the KOR (49 nM).[23] In contrast, our current samples of both 4a and 4b showed no affinity at the KOR (Table 1). Given the very high binding affinity of 1a, contamination of an inactive or weakly active compound with even traces of 1a will cause large errors