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The adsorption of pyrrole, aniline, 3-pyrroline, and pyrrolidine on the Si(001)-(2 × 1) surface has been studied using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Both pyrrole and aniline retain their aromatic character after bonding to the surface. Spectroscopic evidence indicates that each of these aromatic molecules can attach to the Si(001) surface via cleavage of one N-H bond, linking the molecule to the surface through a Si-N tether. Isotopic studies of pyrrole show evidence for additional cleavage of C-H bonds. While strong selectivity favoring bonding through the nitrogen atom is observed for the aromatic molecules, the unsaturated molecule 3-pyrroline shows evidence for at least two bonding configurations. XPS and FTIR data show that 3-pyrroline can bond either through the nitrogen atom with cleavage of an N-H bond, or through the CdC bond via the surface equivalent of a [2 + 2] cycloaddition reaction. Pyrrolidine appears to bond only through the nitrogen atom. Potential factors controlling the selectivity in bonding and the role of aromaticity in controlling reaction pathways on silicon surfaces are discussed. † Part of the special issue "John T. Yates, Jr. Festschrift".

Superhydrophobic surfaces on engineering materials are prepared via a convenient solution‐immersion method. The binary geometric structures at the micro‐ and nanometer scale bestow superhydrophobic properties on the surfaces. The surfaces show stable superhydrophobicity even in many corrosive solutions, such as acidic or basic solutions over a wide pH range, and also in salt solutions. The procedure is time‐saving, inexpensive, and fairly facile to carry out. It is expected that this facile technique will accelerate the large‐scale production of superhydrophobic engineering materials with new industrial applications.

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The interactions of primary, secondary, and tertiary alkylamines with the Si(001) surface have been investigated using x-ray/ultraviolet photoelectron spectroscopy, Fourier transform infrared spectroscopy and scanning tunneling microscopy. Experimental and computational results show that alkylamines bond to the surface through the nitrogen atom. Primary alkylamines such as hexylamine bond to the surface by breaking only one N–H bond. Secondary alkylamines such as dimethylamine and N-methylpentylamine cleave only the N–H bond, leaving the N–C bonds intact. Tertiary alkylamines, such as trimethylamine and N,N-dimethylbutylamine, can form stable dative-bonded adducts on the surface that are characterized by very high N(1s) binding energies of 402.2 eV. The ability to form dative-bonded adducts between tertiary alkylamines and Si(001) stems from the capability of electron transfer from nitrogen to the surface. Our results show that this charge exchange controls the propensity for N–H vs N–C bond cleavage.

Water-soluble DNA cross-linking phenol and biphenol derivatives 3 and 6 have been synthesized by a Mannich reaction. Both of them can cross-link DNA by photoactivation using visible light (wavelength > 400 nm). Compound 6 can cross-link DNA at pH 5.0 and 7.7, whereas no cross-link was observed at pH 10.0. Density functional theory (DFT) calculation indicated that 6 displays a twist structure. Therefore, it could bind to DNA naturally and has potent property to cross-link DNA after photoactivation.

A series of tridentate NˆNˆN iron(II) and cobalt(II) dichloride complexes bearing 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines were synthesized and characterized by elemental and spectroscopic analyses. Single-crystal X-ray diffraction studies of representative examples of the cobalt and iron complexes confirm distorted bipyramidal geometry around the metal center. Upon coordination of a methanol solvent molecule, a geometry change to distorted octahedral was observed. The steric and electronic effects on catalytic activity are evaluated for different substituents in the arylimino part of the ligand: Me, Et, i Pr, Cl, and Br in ortho-and Me and H in para-position. On treatment with methylaluminoxane (MAO) or modified MAO (MMAO), the iron(II) complexes exhibited good activities of up to 10 6 g • mol -1 (Fe) • h -1 for ethylene oligomerization and moderate activities for polymerization, while cobalt(II) complexes showed moderate activities for ethylene dimerization. The best activities were observed with iron complexes with bulky i Pr groups in the aryl moiety. In comparison to the analogues containing the 2-(1-alkyl-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines, the iron complexes bearing 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines showed the best activity toward ethylene reactivity.

a b s t r a c tA series of 2-[1-(2,6-dibenzhydryl-4-chlorophenylimino)ethyl]-6-[1-aryliminoethyl]pyridyl cobalt(II) dichloride complexes (Co1eCo5) were prepared and characterized by elemental and spectroscopic analysis. The molecular structures of the representative cobalt complexes Co1 and Co4 were determined by singlecrystal X-ray diffraction, and revealed a pseudo-square-pyramidal geometry around each cobalt atom. Upon activation with either MMAO or MAO, all cobalt pre-catalysts exhibited high activities toward ethylene polymerization and produced polyethylene products with narrow molecular distributions (1.98e3.61) and molecular weights in the range 72.3e665 kg/mol; the latter is higher than any other molecular weight of polyethylenes obtained by previous cobalt pre-catalysts. Reaction parameters and the nature of the ligands were investigated for their influence on the resultant catalytic activities and properties of the polyethylene products obtained.