Isolation and Crystallographic Characterization of Two,Nonisolated Pentagon Endohedral Fullerenes: Ho3N@C2(22010)-C78 and Tb3N@C2(22010)-C78

Purified samples of Ho₃N@C₂(22010)-C₇₈ and Tb₃N@C₂(22010)-C₇₈ have been isolated by two distinct processes from the rich array of fullerenes and endohedral fullerenes present in carbon soot from graphite rods doped with Ho₂O₃ or Tb₄O₇. Crystallographic analysis of the endohedral fullerenes as cocrystals with Ni(OEP) (in which OEP is the dianion of octaethylporphyrin) shows that both molecules contain the chiral C₂(22010)-C₇₈ cage. This cage does not obey the isolated pentagon rule (IPR) but has two sites where two pentagons share a common C−C bond. These pentalene units bind two of the metal ions, whereas the third metal resides near a hexagon of the cage. Inside the cages, the Ho₃N or Tb₃N unit is planar. Ho₃N@C₂(22010)-C₇₈ and Tb₃N@C₂(22010)-C₇₈ use the same cage previously found for Gd₃N@C₂(22010)-C₇₈ rather than the IPR-obeying cage found in Sc₃N@D_3h-C₇₈.     

One-pot synthesis of 3-arylaminomaleimides from terminal alkynes and isocyanates

The reaction of aryl acetylide anions with phenyl isocyanate and subsequent addition of a protonating agent such as ethanol affords good yields of 3-aminomaleimides, formed by the cyclization of one molecule of alkyne with two isocyanates. When the reaction is quenched with water instead, cyclopentadienone imines are formed as the major products.     

A numerical algorithm for pricing electricity derivatives for jump-diffusion processes based on continuous time lattices

We present a numerical algorithm for pricing derivatives on electricity prices. The algorithm is based on approximating the generator of the underlying price process on a lattice of prices, resulting in an approximation of the stochastic process by a continuous time Markov chain. We numerically study the rate of convergence of the algorithm for the case of the Merton jump-diffusion model and apply the algorithm to calculate prices and sensitivities of both European and Bermudan electricity derivatives when the underlying price follows a stochastic process which exhibits both fast mean-reversion and jumps of large magnitude.     

Optical image asymmetric cryptosystem using fingerprint based on iterative fraction Fourier transform

A novel asymmetric cryptosystem for optical image is proposed using fingerprint based on iterative fractional Fourier transform. To enhance the security, a hyperchaotic phase generated by a 4D Lorenz system is considered as the public key in the proposed encryption system, while the private key is emerged by the retrieved phase and fingerprint. In the encryption process, the secret information is hid into the hyperchaotic phase. Subsequently, the private key can be obtained by a reversible operation. To decrypt the original image, the ciphertext and private key are imported into the input plane of fractional Fourier system. This system is also applicable for information authentication because the fingerprint is used both in encryption and decryption approach. Some numerical simulations have been done to test the validity and capability of the encryption system.     

Remarkably large remote-stereocenter-induced chromatographic differences: azulenyl 1,5-diols

A series of four new azulene-1,5-diol diastereomers were prepared and found to exhibit large differences (ΔR_f 0.22–0.46) in silica TLC mobilities despite having stereocenters four bonds apart. The stereoisomers were identified by X-ray crystallography, and in all cases the RR/SS diastereomers were less strongly retained than the RS/SR diastereomers. The crystal structures suggested that this is due to a conformational preference for the CF₃ groups to be nearly perpendicular to the plane of the azulene ring, which caused the dihedral angle between the OH groups to be larger (in the RR/SS diastereomers) or smaller (in the RS/SR diastereomers). The smaller dihedral angles allow the RS/SR diastereomers to simultaneously bind to a silica surface and thus be more strongly retained. Two similar benzene derivatives and several cycloalkanediols with more proximate stereocenters showed little or no difference in mobilities between diastereomers, though the NMR differences were greater. Thus, the azulene ring is an important factor in enforcing the conformational preferences, either through steric interactions with the 4/8 substituents (H or methyl) or its significant dipole moment, or both.     

1-AMINO-1-ARYL- AND 1-AMINO-1-HETEROARYL-METHANEPHOSPHONIC ACIDS AND THEIR N-BENZHYDRYL–PROTECTED DIETHYL ESTERS: PREPARATION AND CHARACTERIZATION

n-Benzhydryl-protected diethyl[3.3pc] esters of 1-amino-1-aryl- (phenyl, cumyl, p-dimethylaminophenyl, piperonyl, 1′-naphthyl, 9′-anthryl, 1′-pyrenyl) and 1-amino-1-heteroaryl- (furyl, 2′-thienyl, 3′-thienyl, 2′-pyrrolyl)-methanephosphonic acids, prepared by the addition of diethyl phosphite to the corresponding benzhydryl imines, have been isolated, purified, and characterized. The presence of chiral α -carbon and prochiral phosphorus in these esters gives rise to complicated features in their NMR spectra, which are discussed. Hydrolysis of the crude 1-aryl compounds in situ gave modest yields of the corresponding aminophosphonic acids (except for 1′-pyrenyl). Of the 1-heteroaryl derivatives, only the 2′-thienyl compound gave the expected aminophosphonic acid; in other cases, alternative[-18pc] modes of decomposition may occur under hydrolytic conditions. NMR and mass spectral data are given for all products.     

THE CRUCIAL ROLE OF INORGANIC RING CHEMISTRY IN THE DEVELOPMENT OF NEW POLYMERS

The field of phosphazene high polymers has developed into a large area of more than 700 different types of macromolecules with novel combinations of properties and diverse applications. Small-molecule phosphazene rings have played a major role in these developments, first as starting materials for polymer synthesis, second as synthetic and structural models for the high polymers, and third as components of hybrid inorganic-organic macromolecules. These three aspects are reviewed, with examples taken from our recent work, together with some thoughts on the development of this and related fields in the future.     

ORGANOPHOSPHORUS COMPOUNDS AS POTENTIAL FUNGICIDES. PART I. N-(ω-GUANI-DINOALKYL)AMINOALKANEPHOSPHONIC ACIDS AND THEIR AMINOPHOSPHONIC PRECURSORS: PREPARATION,NMR SPECTROSCOPY,AND FAST ATOM BOMBARDMENT MASS SPECTROMETRY

Abstract

N-(ω-Aminoalkyl)- and N-(ω-guanidinoalkyl)-aminoalkanephosphonic acids have been prepared from α, ω-diaminoalkanes by reaction with chloromethanephosphonic acid (or an ester of a halogeno-alkanephosphonic acid), followed by treatment with S-methylisothiouronium chloride. Ethylene diamine yielded 1-phosphonomethyl-2-iminoimidazolidine. A number of 1:1 salts of the α, ω-diamines and chloromethanephosphonic acid are also reported. Doubly charged zwitterionic structures are assigned to both ω-amino and ω-guanidino compounds on the basis of ³¹P and ¹³C nmr data. Thus the addition of an excess of acid (D₂SO₄) causes the ³¹P chemical shift to move to higher field, from ca. 8 to 14 ppm, whilst ¹ Jpc increases from ca. 130 to 150 Hz. The ¹H and ¹³C chemical shifts of the terminal methylene groups in the polymethylene chain are unaffected by acidification.

Fast atom bombardment mass spectrometry gives rise to characteristic [M + H]⁺ ions, frequently as the base peak, and to fragmentations involving the loss of phosphorous acid, or the formation of ions resulting from carbon-nitrogen or carbon-carbon cleavage. The compounds show activity against a number of fungal pathogens and other microbial organisms.