Molecule-based photonically switched half and full adder

A single molecule logic gate using electronically excited states and ionization/fragmentation can take advantage of the differences in cross-sections for one and two photon absorption. Fault tolerant optically pumped half adder and full adder are discussed as applications. A full adder requires two separate additions, and the logic concatenation that is required to implement this is physically achieved by an intramolecular transfer along the side chain of 2-phenylethyl-N,N-dimethylamine (PENNA). Solutions of the kinetic equations for the temporal evolution of the concentration of different states in the presence of time-varying laser fields are used to illustrate the high contrast ratios that are potentially possible for such devices.     

Ionic liquid functionalized cellulose as an efficient heterogeneous catalyst for the facile and green synthesis of benzoxazine,pyrazine and quinoxaline derivatives in aqueous media

Immobilization of acidic ionic liquid, 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium hydrogen sulfate on cellulose (Cell-[pmim]HSO₄) as an efficient heterogenous catalyst for the simple and environmentally benign synthesis of benzoxazine, pyrazine and quinoxaline derivatives in aqueous media at room temperature is described. The catalyst was characterized by FTIR spectroscopy and X-ray diffraction pattern. This method provides several advantages such as mild reaction conditions, environmentally friendly catalyst, good to excellent yields and simple work-up procedure.     

Diterpenoids from Salvia ceratophylla

Salvia ceratophylla L. has yielded four known and two new diterpenoids together with two triterpenic acids, a steroid and a flavone. The structures of the compounds were established by spectroscopic analyses. One of the known compounds candidissiol exhibited a high antibacterial activity against Staphylococcus epidermidis and Proteus mirabilis.     

Synthesis and Biological Activity of Novel (E,E)-vic-dioximes

A novel vic-dioxime ligand containing the thiourea group, (4E,5E)-1,3-bis{4-[(4-methylphenylamino)methyl] phenyl}- 2-thiooxaimidazoline-4,5-dione dioxime, (4) mmdH₂ has been prepared from N,N′-bis{4-[(4-methylphenylamino)methyl]phenyl}thiourea, (3) mft and cyanogen di-N-oxide. Mononuclear [M(mmdH)₂], where M = Ni^II, Co^II and Cu^II complexes of the (4) mmdH₂ bidentate ligand have been obtained with a 1:2 metal:ligand ratio, as do most the vic-dioximes. The complexes are formed by coordination of N, N atoms of the ligand. The vic-dioxime ligand and its some transition metal complexes have been characterized by elemental analyses, molar conductance data, magnetic susceptibility, i.r., ¹H-n.m.r and u.v.–vis. spectroscopy. Conductivity measurements have shown that mononuclear complexes are non-electrolytes. In addition, the ligands and metal complexes were screened for antibacterial and antifungal activities by agar well diffusion techniques using DMF as solvent.     

Effect of hexafluoropropylene oxide plasma polymer particle coatings on the rheological properties of boron nitride/poly(dimethylsiloxane) composites

This work explores the use of conformal nanoscale plasma coatings on the surface of boron nitride (BN) powders to control the rheological properties of BN/poly(dimethylsiloxane) (PDMS) composites. BN particles are conformally coated with hexafluoropropylene oxide (HFPO) in a tumbling RF-plasma reactor. Following the HFPO plasma treatment, XPS evidence indicates the presence of thin coating on the surface of the particles having a F:C ratio of 1.77. Filled BN/PDMS composites are investigated using oscillatory shear rheometry in the concentration range of 0.09-0.41 vol% (varphi). The addition of the plasma treated BN particles to the PDMS matrix reduces the complex viscosity by 40-60% when compared with equally loaded control samples across a broad concentration range. The frequency dependence of the maximum packing fraction (varphi(m)=0.38-0.42) is also observed for both treated and untreated particles. The maximum packing fraction does not appear to be significantly affected by the conformal plasma polymer treatment. The investigation has shown that the relative dynamic viscosity of the BN/PDMS can be described by the modified Mooney equation.     

Molecular physics of building blocks of life under isolated or defined conditions

In this paper we motivate the study of biomolecular building blocks under isolated or well defined conditions. We explain why we believe that especially gas phase investigations in combination with quantum chemical calculations can provide new insights into molecular properties, such as structure, molecular recognition, reactivity and photostability. Although the gas phase represents far from in situ conditions, these findings are important for a detailed understanding of biology. We give a short historic overview of gas phase studies of biomolecular building blocks under isolated conditions, present some examples and report the current status of this field. We explain the new quality of synergy between experiment and quantum theory and the unique opportunities therein to discover new pathways for reactivity and to understand biological processes on an atomic level. We sketch the content of this special issue and give a further perspective of the research field of “Spectroscopy of biomolecular building blocks under isolated or defined conditions” and explain the possible connectivity to biology. Received 29 August 2002 Published online 13 September 2002