Analysis of recognition of fructose by imprinted polymers

Binding of fructose to the fructose imprinted polymer (MIP(Frc)) and pinacol imprinted polymer (control) were studied both in batch and a flow through mode. The influence of the cross-linkers ethylene glycol dimethacrylate (EDMA) and trimethylolpropane trimethacrylate (TRIM) on the binding characteristics was analysed. TRIM cross-linked MIPs showed a lower (unspecific) binding for the control polymer (pinacol imprinted) and higher binding of fructose as compared with the EDMA-MIPs. Furthermore interactions of a TRIM cross-linked molecularly imprinted polymer against fructose and its corresponding template were studied using a thermistor. Label-free detection of fructose was realised in the range of 0.5-10mM. The difference in enthalpy changes between specific binding of fructose to boronic acid moieties of the MIP and non-specific binding to the matrix leads to an 18-fold higher apparent imprinting factor than batch binding studies. Cross-reactivity studies using MIP sensor indicate that the interaction of fructose to MIP generates higher signal than disaccharides. The studies described in this paper demonstrate the potential of direct characterisation of molecular binding events.     

Carba-closo-dodecaborates with one or two alkynyl substituents bonded to boron

Salts of the carba-closo-dodecaborate anion with one or two phenyl- or trimethylsilylalkynyl substituents were synthesized by Pd-catalyzed Kumada-type cross-coupling reactions of the corresponding iodinated clusters with alkynyl Grignard reagents. Selective monofunctionalization in the 7- and 12-position of the {closo-CB(11)} cluster was achieved, resulting in salts of the anions: [1-R-12-R'C[triple bond]C-closo-CB(11)H(10)](-) (R = H, Ph; R' = Ph, Me(3)Si (1-4)), [12-Hal-7-PhC[triple bond]C-closo-CB(11)H(10)](-) (Hal = F (5), Cl (6), Br (7)), and [12-F-7-Me(3)SiC[triple bond]C-closo-CB(11)H(10)](-) (8). Furthermore, the disubstituted derivatives [7,12-(RC[triple bond]C)(2)-closo-CB(11)H(10)](-) (R = Ph (9), Me(3)Si (10)) are described. All salts were characterized by multi-NMR, IR, and Raman spectroscopy as well as by mass spectrometry (MALDI). The crystal structures of Cs(+)1 and [Et(4)N](+)6 were determined by single-crystal X-ray diffraction. The spectroscopic and structural properties are compared to values derived from DFT calculations and to data of related boron species with alkynyl groups.     

Pyridine Adducts of Tricyano- and Dicyanoboranes

Cyanoborane adducts of the Lewis acids B(CN)₃, BF(CN)₂, and BH(CN)₂ with pyridine and 4-cyanopyridine have been obtained in high yields. The syntheses were accomplished by oxidation of the readily available potassium salts of the cyano(hydrido)borate anions [BH(CN)₃]⁻ ( MHB ), [BFH(CN)₂]⁻ ( FHB ), and [BH₂(CN)₂]⁻ ( DHB ) with bromine in the presence of the respective pyridine derivative C₅H₅N or 4-CN-C₅H₄N as starting material. All six cyanoborane adducts have been characterized by NMR and vibrational spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The reduction of the cyanoborane adducts has been investigated by cyclic voltammetry and the Lewis acidity of the different cyanoboranes has been assessed using the Gutmann-Beckett method. Selected experimental data and trends are compared to theoretical ones, for example fluoride ion affinities (FIAs).     

Unprecedented Efficient Structure Controlled Phosphorescence of Silver(I) Clusters Stabilized by Carba‐closo‐dodecaboranylethynyl Ligands

{Ag₂(12‐C≡C‐closo‐1‐CB₁₁H₁₁)}_n and selected pyridine ligands have been used for the synthesis of photostable Ag^I clusters that, with one exception, exhibit for Ag^I compounds unusual room‐temperature phosphorescence. Extraordinarily intense phosphorescence was observed for a distorted pentagonal bipyramidal Ag^I₇ cluster that shows an unprecedented quantum yield of Φ=0.76 for Ag^I clusters. The luminescence properties correlate with the structures of the central Ag^I_n motifs as shown by comparison of the emission properties of the clusters with different numbers of Ag^I ions, different charges, and electronically different pyridine ligands.     

Finite Element Analysis of Eigendynamics of Rolling Tires

The eigenvalue analysis of rolling tires is one part of the simulation of tire rolling noise radiation for the reduction of traffic noise. In this paper the general strategies of numerical eigenvalue analysis for nonsymmetric matrices are shown. The special effects observed on rotating bodies are discussed in details. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)