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Abstract: A ditopic receptor 1 bearing silanol groups as anion recognition sites and a 2,2′-bipyridine moiety as a metal-coordination site was synthesized. The X-ray crystallographic analysis revealed that the receptor 1 simultaneously associated Ag+ at the bipyridine site and at the anion recognition site surrounded by two silanol groups and one C–H proton of the bipyridine. The titration experiments suggested the large affinity of the receptor with AgNO3, caused by the cooperative cation and anion binding. The cooperative effect of metal cation could enhance anion recognition property of silanol-based receptor. [Copyright &y& Elsevier]

Abstract: Anion recognition properties of d-ribose-based receptors α- and β-1 were measured by 1H NMR in CDCl3 and MeCN-d 3. Receptor β-1 showed effective binding with anions by cooperative hydrogen bonds of cis-diol. The anomeric isomer α-1 is a less effective anion receptor which has similar cis-diol as a recognition site, indicating that the stereo configuration of the anomeric position is of significant influence on the anion recognition ability. [Copyright &y& Elsevier]

Siloxane-based materials have a wide range of applications. Cage-type oligosiloxanes have attracted significant attention as molecular building blocks to construct novel siloxane-based nanoporous materials with promising applications such as in catalysis and adsorption. This paper reviews recent progress in the preparation of siloxane-based nanoporous materials using alkoxy- and silanol-functionalized cage siloxanes. The arrangement of cage siloxanes units is controlled by various methods, including amphiphilic self-assembly, hydrogen bonding of silanol groups, and regioselective functionalization, toward the preparation of ordered nanoporous siloxane-based materials. [ABSTRACT FROM AUTHOR]

Abstract: Synthesis and anion recognition properties of 2,2′-binaphthalene derivatives bearing two thiourea (1) and urea (2) groups at 8- and 8′-positions were studied. The structure of receptor 1 was determined by X-ray crystallography. UV–vis spectra of the receptors showed characteristic changes around 300–400nm through isosbestic points upon the addition of biologically relevant anions such as acetate, dihydrogenphosphate, and chloride in MeCN and DMSO due to restriction of the rotation around the single bond connecting two naphthyl moieties by cooperative guest binding of two recognition sites. Job’s plots showed 1:1 complexation for guest anions. The fluorescence quantum yields of free form of 1 and 2 in MeCN were determined to be 0.021 and 0.57, respectively. The fluorescence intensities of the receptors diminished upon the addition of anions in MeCN. The association constants of receptors 1 and 2 were one or two orders of magnitude greater than the corresponding monothiourea and urea receptors 3 and 4 indicating cooperative hydrogen bonding with guest anions. The selectivity trends of association of anions were F−>AcO−>H2PO4 −>Cl−>>HSO4 −≈NO3 −≈Br−≈I− for 1, and F−>AcO−≈Cl−>H2PO4 −>Br−>HSO4 −>I−≈NO3 − for 2. Receptor 2 showed remarkable Cl− selectivity presumably owing to suitable orientation for effective hydrogen bond formation with Cl−. [ABSTRACT FROM AUTHOR]

Abstract: 1H NMR dilution experiment and FTIR were used to investigate the hydrogen bonded interaction in three different types of incompletely condensed silsesquioxanes (POSS-mono-ol, POSS-diol and POSS-triol). For POSS-triol, there existed a dynamic equilibrium between single molecule and hydrogen-bonded dimer, and the dimerization constants (K dim) of POSS-triol in different solvents were determined by 1H NMR dilution experiment. In addition, based on hydroxy group which acted as hydrogen bond donors, the possibility of three POSS silanols as anion receptors to form host–guest complexes was also explored in this paper. [Copyright &y& Elsevier]

Abstract: To explore the anion recognition ability of silanol derivatives, ESI-MS and 1H NMR titrations of a 1,3-disiloxanediol 1 with anions were studied in CDCl3 and MeCN-d 3. The results indicate that 1 showed strong binding to anions such as AcO− and halides. [Copyright &y& Elsevier]