in this paper,the molecular geometry for three tautomers of uracil and four tautomers of cytosine has been analyzed. vibrational ir spectra of the tautomers were   investigated at hf and b3lyp level using the ab initio 6-31g* and lanl2dz basis sets from the program package gaussian 98 (a.7 public domain version). the physico-chemical and biochemical properties of uracil and cytosine are one of...

The conformations of a series of benziporphyrins, naphthiporphyrins, oxybenziporphyrins, and related structures were minimized using DFT-B3LYP/6-311++G(d,p). The relative stabilities of the tautomers for each series were calculated using M06-2X and B3LYP-D functionals, and bond lengths were obtained. The diatropic properties of each species were assessed by calculating nucleus independent chemi...

The title compound, C13H22N2O, crystallized as a pyrazolol tautomer. The 12-membered macrocycle has a distorted chair conformation. In the crystal, mol-ecules are linked via pairs of O-H⋯N hydrogen bonds, forming inversion dimers. The dimers are linked via N-H⋯π and C-H⋯π inter-actions, forming slabs parallel to the bc plane.

The title compound, also known as 7-nitro-tropolone, C7H5NO4, exists in the crystalline state as the 2-hy-droxy-7-nitro-cyclo-hepta-2,4,6-trien-1-one tautomer and not as 2-hy-droxy-3-nitro-cyclo-hepta-2,4,6-trien-1-one. The dihedral angle between the ring and the nitro group is 70.3 (2)°. In the crystal, neighbouring mol-ecules are linked into dimers by a pair of O-H⋯O hydrogen bonds. In additi...

An efficient sensor for Zn(2+) and Cu(2+) was designed based on different binding modes. The sensor displays ratiometric signals for Zn(2+), due to the Zn(2+)-triggered amide tautomerization; while dual-mode selective behaviors for Cu(2+) result from the deprotonation of the amide tautomer.

We demonstrate in this joint experimental and theoretical study how one can alter electron transport behavior of a single melamine molecule adsorbed on a Cu (100) surface by performing a sequence of elegantly devised and well-controlled single molecular chemical processes. It is found that with a dehydrogenation reaction, the melamine molecule becomes firmly bonded onto the Cu surface and acts ...

We have recorded NOESY spectra of two non-selfcomplementary undecanucleotide duplexes. From the observed NOEs we do not detect any significant distortion of the helix when a G-C pair is replaced by a G-T pair and the normal interresidue connectivities can be followed through the mismatch site. We conclude that the 2D spectra of the non-exchangeable protons do not allow differentiation between a...

The pharmacokinetics and safety of cefotetan (YM09330) were examined after intravenous administration of single and multiple doses to normal volunteers. Cefotetan was well tolerated in single doses of 500 to 3,000 mg and in multiple doses of 500 and 1,000 mg at 12-h intervals for 1 and 3 days. These doses produced high plasma levels. The half-life (3 h) of cefotetan was longer than that of cefa...