Synthesis of isochromene esters utilizing 1,6-addition of nucleophiles to benzopyranylidenetungsten(0) complexes

[reaction: see text] A concise method for the preparation of isochromene carboxylates has been developed by the regioselective 1,6-addition of various nucleophiles such as Grignard reagents, alkoxide, and cyanide onto benzopyranylidenetungsten(0) complexes, followed by iodine oxidation of the addition intermediates.     

Reaction of an Introverted Carboxylic Acid with Carbodiimide

The reaction of carboxylic acids with carbodiimides is reviewed, and an ‘introverted’ carboxylic acid is proposed as a means of trapping reactive intermediates along the reaction pathway. The introverted acid is a cavitand with the carboxylic function directed toward the floor of the cavity. Its reaction with diisopropyl carbodiimide gives a covalent adduct that is either the elusive O-acylisourea or the commonly encountered N-acylurea.     

ACTION SPECTRA FOR INHIBITION OF HYPOCOTYL GROWTH OF WILD-TYPE PLANTS AND OF THE hy2 LONG-HYPOCOTYL MUTANT OF Arabidopsis thaliana L.

Abstract— An analysis was made by action spectroscopy, using the Okazaki Large Spectrograph, of the inhibition of hypocotyl elongation of wild-type plants and the hy2 mutant of Arabidopsis thaliana. Two day old etiolated seedlings were irradiated for 8 h with monochromatic light and left in the dark for 16 h before measurement of hypocotyl length. Spectrophotometric measurement showed that levels of phytochrome in the etiolated tissue of the hy2 mutant were less than 9% of those in the wild type. The action spectra of the wild type looked like those of high irradiance response and showed peaks at 375, 450, 625 and 725 nm, whereas the action spectra of hy2 showed only the peaks at 375 and 450 nm. Monochromatic light of wavelengths longer than 500 nm had no significant inhibitory effects on hy2 plants. Blue and UV-A light were about five times more effective in the wild type than in hy2 plants. Severe inhibitory effects were observed with UV-B light. It is concluded that inhibition of the growth of the hypocotyl involves combined actions of phytochrome and a putative blue/UV-A photoreceptor(s).     

High resolution images of Mo2C(0001)- structure by scanning tunneling microscopy

A C-terminated structure on Mo₂C(0001) was observed by scanning tunneling microscopy. The structure was observed as a honeycomb structure with dark depressions corresponding to C atoms which make up the lattice. High resolution imaging was possible at low tunneling resistance less than 1 MΩ. Each C atom appears as a shallow sombrero protrusion predicted by theoretical calculations of C atoms on a metal substrates. It is concluded that the C atoms occupied threefold hollow sites of the (1×1) Mo layer of the substrate and a model for the structure is proposed.     

Imaging of atomic-scale structure of oxide surfaces and adsorbed molecules by noncontact atomic force microscopy

Atom-resolved images of a TiO₂(110)-(1×1) surface and individual formate and acetate ions adsorbed on the surface were obtained by noncontact atomic force microscopy (NC-AFM) in ultrahigh vacuum. In contrast to previous scanning tunneling microscopic studies imaging five-fold coordinated Ti atoms, outermost atoms of bridge-bound oxygen ridges of the surface were resolved as protruding rows by NC-AFM. High-resolution image of the surface revealed that the bridging oxygen atoms on terraces ordered in a (1×1) periodicity. Randomly distributed point and multiple defects of oxygen atoms were also imaged as dark spots. The (2×1) overlayer of formate and acetate ions were resolved as ordered bright spots. Dispersed formate ions at a low coverage were also observed as bright spots between the bridging oxygen ridges along the [001] direction.