Atomic level analysis of biomolecules by the scanning atom probe

Utilizing the unique features of the scanning atom probe (SAP) the binding states of the biomolecules, leucine and methionine, are investigated at atomic level. The molecules are mass analyzed by detecting a single atom and/or clustering atoms field evaporated from a specimen surface. Since the field evaporation is a static process, the evaporated clustering atoms are closely related with the binding between atoms forming the molecules. For example, many thiophene radicals are detected when polythiophene is mass analyzed by the SAP. In the present study the specimens are prepared by immersing a micro cotton ball of single walled carbon nanotubes (SWCNT) in the leucine or methionine solution. The mass spectra obtained by analyzing the cotton balls exhibit singly and doubly ionized carbon ions of SWCNT and the characteristic fragments of the molecules, CH₃, CHCH₃, C₄H₇, CHNH₂ and COOH for leucine and CH₃, SCH₃, C₂H₄, C₄H₇, CHNH₂ and COOH for methionine.     

Tetrachloroferrate (III) Salts of BDH-TTP [2,5-Bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] and BDA-TTP [2,5-Bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene]: Crystal Structures and Physical Properties

Three FeCl₄ salts based on non-tetrathiafulvalene (TTF) donors, 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP) and 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP), have been prepared and characterized as κ-(BDH-TTP)₂FeCl₄, β-(BDA-TTP)₂FeCl₄, and (BDA-TTP)₃FeCl₄ · PhCl. The κ-(BDH-TTP)₂FeCl₄ salt, with a room-temperature conductivity (σ_rt) of 39 S cm⁻¹, is metallic down to 1.5 K, and its magnetic susceptibility obeys the Curie-Weiss law with a Curie constant (C) of 4.25 emu K mol⁻¹ and a Weiss constant (θ) of 0.041 K. β-(BDA-TTP)₂FeCl₄ exhibits metallic behavior (σ_rt=9.4 S cm⁻¹) with a sharp metal-to-insulator (MI) transition (T_MI=113 K) and antiferromagnetic ordering with the Néel temperature of near 8.5 K, whereas the solvated (BDA-TTP)₃FeCl₄ · PhCl salt is a semiconductor with a thermal activation energy of 0.11 eV (σ_rt=2.0× 10⁻² S cm⁻¹) and exhibits Curie-Weiss behavior (C=4.42 emu K mol⁻¹, θ=−0.35 K).     

Stereocontrolled synthesis of 8,11-dideoxytetrodotoxin,unnatural analogue of puffer fish toxin

[structure: see text] 8,11-Dideoxytetrodotoxin, an unnatural tetrodotoxin analogue, was synthesized in a highly stereoselective manner from a common intermediate in our synthetic studies on tetrodotoxin. The synthesis features neighboring group participation of trichloroacetamide for stereoselective hydroxylation, protection of ortho ester, and guanidine installation with Boc-protected isothiourea.     

Cyclization of 1,6-enynes with allylic chromate species

[reaction: see text] Treatment of 1,6-enynes with tetramethallylchromate induces a cyclization reaction with concurrent introduction of a methallyl group. A catalytic amount of CrCl(3) combined with methallylmagnesium chloride also achieves this cyclization process. The resultant cyclic organometallic species undergo further functionalization upon reaction with electrophiles.     

Self-oscillation of polymer chains with rhythmical soluble-insoluble changes

Self-oscillation of polymer chains in an aqueous solution has been achieved. The ruthenium catalyst for the Belousov-Zhabotinsky reaction was polymerized by using N-isopropylacrylamide and dissolved into the solution containing the BZ substrates. Periodical soluble-insoluble changes of the polymer chain were spontaneously induced by the BZ reaction. The conformational oscillations of the polymer were measured as the optical transmittance changes of the solution. This is the first report that rhythmical and reversible soluble-insoluble changes of polymer chains are realized under constant and homogeneous conditions. The transducing system from chemical energy of the BZ reaction to optical information has been constructed.