Dinitrophenylhydrazine: β-cyclodextrin inclusion complex as a novel fluorescent chemosensor probe for Ce4+

Research on Chemical Intermediates - An inclusion complex of 2,4-dinitrophenyl hydrazine (DNPH) with β-cyclodextrin (β-CD) was prepared and investigated using UV–visible and...     

A new class of laser dyes from acridinedione derivatives

Synthesis of 10-aryl-3,4,6,7,9,10-hexahydro-1,8(2H,5H)-acridinedione as a new class of laser dyes is reported. These dyes lase around 475–495 nm and are compared to the standard dye coumarin 102.     

Application of Shannon-like diversity measures to cell-based chemistry spaces

The use of multi-dimensional “chemistry spaces” to represent large compound collections has become widespread in pharmaceutical research. In such spaces compounds are treated as points. Points in close proximity represent similar compounds, while distant points represent dissimilar compounds. Assessing the diversity of a compound collection, thus, is tantamount to characterizing the distribution of points in chemistry space. To facilitate many procedures such as selecting subsets of compounds for screening, for compound acquisition and designing combinatorial libraries, chemistry spaces have been partitioned into sets of non-overlapping, multi-dimensional cells, which are generated by dividing each axis into a number of equal-sized bins. This leads to a lattice of (N_bins)^N_dim{(N_{bins})^{N_{\rm dim}}} cells, where N _bins is the number of bins on each axis and N _dim is the dimensionality of the space. One diversity measure that is typically used in cell-based chemistry spaces is identical in form to Shannon entropy, D_Ncpd^cpd{D_{N_{cpd}}^{cpd}} A normalized measure of this Shannon entropy given by, D_rel^cpd{D_{rel}^{cpd}} enables comparison between compound collections that occupy different number of occupied cells. Although D_rel^cpd{D_{rel}^{cpd}} characterizes the uniformity and “spreadout” of the corresponding compound collection, it treats cells as positionally independent. Some of the positional information lost can be recaptured by another diversity measure, which is also related in form to Shannon entropy. This new measure D_Nbin^cell (l){D_{N_{bin}}^{cell} (\lambda)} characterizes the distribution of occupied cells along each axis of chemistry space. The normalized measure á D_rel^cell ñ{\left\langle {D_{rel}^{cell}}\right\rangle} over all axes is given then by the average. Examples illustrating the applicability of these two Shannon-like measures to compound collections are presented.     

Preparation of Co/Pd alloy particles dispersed multiwalled carbon nanotube supported nanocatalysts via gamma irradiation

New multiwalled carbon nanotube/silica supported cobalt-palladium bimetallic nanocatalysts (MWNT@silica/Co–Pd NPs) were prepared by a simple one step gamma irradiation method. The method involves the in-situ surface modification of MWNT with silica (MWNT@silica) and simultaneous formation of Co–Pd bimetallic NPs using gamma irradiation. The bimetallic NPs were stabilized by silica particles formed over the surface of MWNT. Extensive characterization studies have been performed on structural, morphological, and electrochemical, aspects of MWNT@silica/Co–Pd NPs. MWNT@silica/Co–Pd NPs were characterized by field emission scanning microscopy (FESEM), UV–visible spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy. The influence of irradiation dosage levels on the stabilizing effect of silica particles has been studied. The electrolytic activities of the MWNT@silica/Co–Pd NPs were investigated by cyclic voltammetry.     

Synthesis of New C(2)‐Substituted gluco‐Configured Tetrahydroimidazopyridines and Their Evaluation as Glucosidase Inhibitors

The gluco‐configured C(2)‐substituted tetrahydroimidazopyridines 8 – 14 were prepared and tested as inhibitors of the β‐glucosidases from Caldocellum saccharolyticum and from sweet almonds, and of the α‐glucosidase from brewer's yeast. All new imidazopyridines are nanomolar inhibitors of the β‐glucosidases and micromolar inhibitors of the α‐glucosidase. The 3‐phenylpropyl derivative 14 proved the strongest inhibitor of the Caldocellum β‐glucosidase (K_i = 0.9 nM ), only slightly weaker than the known 2‐phenylethyl analogue 7 , and the propyl derivative 13 is the strongest inhibitor of the sweet almond β‐glucosidases (K_i = 3.2 nM ), again slightly weaker than 7 . There is no strong dependence of the inhibition on the nature of the C(2)‐substituent and no clear correlation between the inhibitory strength of the known manno‐configured imidazopyridines 2 – 6 and the gluco‐analogues 8 – 12 . While most manno‐imidazopyridines are competitive inhibitors, the gluco‐analogues proved non‐competitive inhibitors of the Caldocellum β‐glucosidase and mixed‐type or partial mixed‐type inhibitors of the sweet almond β‐glucosidases.     

Simple and mild stereoselective O-glycosidation using 1,2-anhydrosugars under neutral conditions

The ring opening of α-d-1,2-anhydrohexapyranoses with phenols proceeded smoothly in ethyl acetate (neutral conditions) in the absence of metal ion catalysts or additives to stereoselectively furnish 1,2-cis-α-aryl glycosides as the major product and 1,2-trans-β-aryl glycosides as the minor product in good yields. Under similar conditions, this ring opening reaction with alcohols afforded exclusively β-alkyl glycosides in excellent yields.     

Synthesis of spiro[3,4‐diaryl‐4,5‐dihydroisoxazole‐5,2′‐1′,2′,3′,4‐tetrahydro‐1′‐naphthalenone]

Synthesis of a series of novel spiro[3,4‐diaryl‐4,5‐dihydroisoxazole‐5,2′‐1′,2′,3′,4′‐tetrahydro‐1′‐naphthalenone] has been described by the regioselective cycloaddition of nitrile oxides with 2‐arylmethylene‐1,2,3,4‐tetrahydro‐1‐naphthalenone. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:463–467, 2001     

An information-theoretic characterization of partitioned property spaces

A methodology, derived by analogy to Shannon’s information-theoretic theory of communication and utilizing the concept of mutual information, has been developed to characterize partitioned property spaces. A family of non-intersecting subsets that cover the “universe” of objects represents a partitioned property space. Each subset is thus an equivalence class. A partition and it’s associated equivalence classes can be generated using any one of a number of procedures including hierarchical and non-hierarchical clustering, direct approaches using rough set methods, and cell-based partitioning, to name a few. Thus, partitioned property spaces arise in many instances and represent a very large class of problems. The approach is based on set-valued mappings from equivalence classes in one partition to those in another and provides a coarse-grained means for comparing property spaces. From these mappings it is possible to compute a number of Shannon entropies that afford calculation of mutual information, which represents that amount of information shared by two partitions of a set of objects. Taking the ratio of the mutual information with the maximum possible mutual information yields a quantity that measures the similarity of the two partitions. While the focus in this work is directed towards small sets of objects the approach can be extended to many more classes of problems that can be put into a similar form, which includes many types of cheminformatic and biological problems. A number of scenarios are presented that illustrate the concept and indicate the broader class of problems that can be handled by this method.