The Asymptotic Linearity Theorem for the study of additivity problems of the zero-point vibrational energy of hydrocarbons and the total pi-electron energy of alternant hydrocarbons

By using the approach via the aspect of form and general topology, as well as basic notions of abstract algebra, a theoretical framework has been developed which elucidates the mechanism of the additivity relationships between structure and properties in molecules having many identical moieties. The main theorem, the Asymptotic Linearity Theorem (ALT), together with an auxiliary theorem, the a Independence Theorem, implies that the zero-point vibrational energy (or total pi-electron energy for the case of alternant hydrocarbons)E _n of a linearly extended system B-A _n -B having n repeating identical moieties has the asymptotic expansionE _n = n + +o(1) as n , where is independent of the choice of the end moieties B and B. The theorem being formulated in a general context, the actual implication of the ALT is much broader than the above two applications would indicate.On leave from: Institute for Fundamental Chemistry, 34-4 Nishihiraki-cho, Takano, Sakyo-ku, Kyoto 606, Japan.     

Structural analysis of certain linear operators representing chemical network systems via the existence and uniqueness theorems of spectral resolution VII

The present Part VII of this series of articles is a direct extension of Part VI, where (1) fundamental methodology in the repeat space theory (RST) and (2) frontier electron theory of reactivity indices were theoretically linked. This part presents an estimate of the size of the regular index set, which was a central notion in Part VI, and two new theorems that are simpler and more powerful than the main theorem in Part VI. The main theorem in this part enables one to globally contextualize the Generalized Alpha Existence Theorem (a theorem essential in the RST and proved in Part V) and the μ Existence Theorem (derived from the main theorem in Part VI) into the star algebra structure of the generalized repeat space ??_r(q, d). © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Polycyclic N-hetero compounds. XXXIII. Syntheses of 4-substituted 6,7-dihydro-5H-benzo[6,7]-cyclohepta[1,2-d]pyrimidines and their inhibitory activities on platelet aggregation and on reserpine-induced hypothermia

Various 4-substituted 6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-d]pyrimidines were synthesized by the reaction of 4-chloro-6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-d]pyrimidine with amines. Their inhibitory activities against collagen-induced platelet aggregation and also against reserpine-induced hypothermia in mice were investigated.     

Synthesis,crystal structures,and magnetic properties of two cyano-bridged tungstate(V)-manganese(II) bimetallic magnets

The reaction of manganese acetate with octacyanotungastate in an aqueous solution of concentrated acetic acid gives two new three-dimensional cyano-bridged manganese(II)-tungstate(V) bimetallic assemblies, [Mn(II)(2)(H(2)O)(2)(CH(3)COO)][W(V)(CN)(8)].2H(2)O (1) (tetragonal space group I4/mcm, a = b = 11.9628(9) A, c = 13.367(2) A, and Z = 4) and Cs(I)(0.5)Mn(II)(2)[W(V)(CN)(8)](CH(3)CO(2))(1.5).H(2)O (2) (monoclinic space group C2/c, a = 16.274(2) A, b = 22.948(6) A, c = 13.196(1) A, beta = 128.040(6) degrees, and Z = 8). In complex 1, W(V)(CN)(8) adopts a square antiprismatic geometry, and each CN group coordinates to the Mn(II) ions forming W-Mn(4)-W-Mn(4)-...columnar linkages where four sites on the Mn(II) ion with octahedral geometry are occupied by CN groups. The columns are parallel and interlock, yielding a network structure. Complex 2 contains two different coordination geometries for W(V)(CN)(8), namely, square antiprismatic and dodecahedral. The columnar structures appear also in 2, where the Mn(II) ions in two different environments provide three and four coordinated sites to the CN groups. The columns are bridged by both dodecahedral W(V)(CN)(8) groups and acetates. Cs ions were intercalated in the lattice by the formation of short attractive contacts with the acetates. The field-cooled magnetization, ac susceptibility, and the field dependence of magnetization measurements show that both 1 and 2 are ferrimagnets with ordering temperatures 40 and 45 K, respectively. The investigation of the magnetostructural correlation shows that the ferrimagnetic ordering in 1 and 2 are attributed to the dominant antiferromagnetic exchange pathways d(z)2(W)-d(x')(y')(Mn) and d(x)2(-y)2(W) - d(x')(y')(Mn).     

Cationic polymerization of 1-ethoxy-1,3-butadiene

cis- and trans-1-Ethoxy-1,3-butadienes were polymerized by a variety of cationic agents in various solvents at ?78°C. The trans ether, which is the more stable isomer, was found to have greater polymerizability than the cis ether. The trans monomer gave polymers predominantly of the trans-1,4 type, whereas the cis monomer showed a tendency toward the formation of polymers having the microstructure of the 1,2 type. It was concluded that, in the cis ether, the carbon atom which is the most vulnerable to the attack of carbonium ions is the one at the 2-position, whereas, in the case of the trans isomer, the terminal 4-carbon is the most reactive center. The conclusion was confirmed from the results of acetal addition reaction catalyzed by boron trifluoride etherate. The marked contrast in the mode of reaction of the two isomeric ethers toward carbonium ions was interpreted in terms of the difference in the degree of bonding in the transition state.     

Large-Scale Chirality Measures and General Symmetry Deficiency Measures for Functional Group Polyhedra of Proteins

Functional Group Polyhedra provide a simplified representation of the most essential spatial features of macromolecules, especially, of globular proteins. Since the functional group polyhedron model focuses on large scale features, the chirality and other symmetry deficiency measures of these molecules, when adapted to these polyhedra, should also be based on the characterization of large scale shape features. Two new approaches for the evaluation of such symmetry deficiency and chirality measures are presented.     

The conformational features of palytoxin in aqueous solution

Conformational features of palytoxin and acetylated palytoxin were investigated by detailed analyses of NOESY spectra. The conformational differences between palytoxin and acetylated palytoxin may account for the difference in the assembly state of palytoxin, which exists as an associated dimer, and the acetylated derivative, which exists as a monomer in aqueous solution. Two palytoxin units in the dimer may come in contact with each other at the hydrophobic region (C21-40) and the region around two conjugated double bonds (C60-84). The amino group of palytoxin is important for biological activities via Na/K ATPase, but it was not found to be involved in the contact faces of the two palytoxin units. This information should aid in revealing how palytoxin interacts with Na/K ATPase.     

Electroreductive intramolecular coupling of aromatic beta- and gamma-imino esters: a new synthetic method for N-alkoxycarbonyl-2-aryl-3-ones and cis-2-aryl-3-ols of pyrrolidines and piperidines

The electroreduction of aromatic beta- and gamma-imino esters prepared from beta-alanine and GABA in the presence of chlorotrimethylsilane and subsequent N-alkoxycarbonylation of the resulting five- and six-membered cyclized amines gave mixed ketals of N-alkoxycarbonyl-2-arylpyrrolidin-3-ones and 2-arylpiperidin-3-ones, respectively. The best result of the electroreductive intramolecular coupling was achieved using Bu(4)NClO(4) as a supporting electrolyte and a Pb cathode in THF. Acid hydrolysis of the mixed ketals afforded N-alkoxycarbonyl-2-arylpyrrolidin-3-ones and 2-arylpiperidin-3-ones in good yields. The reduction of these ketones with NaBH(4) in methanol afforded the corresponding N-alkoxycarbonyl-cis-2-arylpyrrolidin-3-ols and cis-2-arylpiperidin-3-ols diastereospecifically.