A Convenient Procedure for the Preparation of Alkyl Nitriles from Alkyl Halides. Acetone Cyanohydrin as an In Situ Source of Cyanide Ion

A convenient preparation of alkyl nitriles from alkyl halides is described. Acetone cyanohydrin is employed as the source of cyanide ion.     

A turn on ESIPT probe for rapid and ratiometric fluorogenic detection of homocysteine and cysteine in water with live cell-imaging

5(Benzothiazol-2-yl)-4-hydroxyisophthalaldehyde (BHI), an intense ESIPT containing molecule in mixed media loses its properties due to resonance-assisted H-bond (RAHB) in absolute water. Due to resonance-assisted H-bond the o-aldehyde is more reactive than the other one. With addition of cysteine/homocysteine into this solution the o-aldehyde group gets transformed into thiazolidine/thiazine ring, respectively, and the phenolic proton becomes free enough for transfer to nitrogen of the benzothiazole ring in excited state, that is, the ESIPT of BHI is turned on. Thus we can detect cysteine/homocysteine in water as well as in live cells.     

Bipartite Q-polynomial distance-regular graphs and uniform posets

Let Γ denote a bipartite distance-regular graph with vertex set X and diameter D≥3. Fix x∈X and let L (resp., R) denote the corresponding lowering (resp., raising) matrix. We show that each Q-polynomial structure for Γ yields a certain linear dependency among RL ², LRL, L ² R, L. Define a partial order ≤ on X as follows. For y,z∈X let y≤z whenever ?(x,y)+?(y,z)=?(x,z), where ? denotes path-length distance. We determine whether the above linear dependency gives this poset a uniform or strongly uniform structure. We show that except for one special case a uniform structure is attained, and except for three special cases a strongly uniform structure is attained.