The title compound, C(14)H(12)FNO, crystallizes as the trans phenol-imine tautomer. The two benzene rings are essentially coplanar, being inclined to one another by 9.28 (7)°. This is at least in part due to the intra-molecular O-H⋯N hydrogen bond between the hy-droxy O atom and the imine N atom. The crystal structure is stabilized by an array of weak C-H⋯O and C-H⋯F inter-actions, which link t...

We present calculations for the mechanism and the barrier heights of tautomerization of adenine. We find various pathways for the 9(H) <--> 7(H) and 9(H) <--> 3(H) tautomerization. One mechanism for the 9(H) --> 7(H) tautomerization involves an sp(3)- or carbene-type intermediate, whereas the other proceeds via imine intermediates. Tautomerization from the 9(H) tautomer to 7(H) or 3(H) is predi...

The structure of the Asn102 mutant of trypsin was determined in order to distinguish whether the reduced activity of the mutant at neutral pH results from an altered active site conformation or from an inability to stabilize a positive charge on the active site histidine. The active site structure of the Asn102 mutant of trypsin is identical to the native enzyme with respect to the specificity ...

In the title compound, C14H15N5OS, the tautomer present in the solid state is that in which the immediately exocyclic N atom bears the H atom. The central five-membered ring is almost planar (r.m.s. deviation = 0.025 Å), but both its N atoms are significantly pyramidalized. A classical hydrogen bond from the N-H group to the cyanide N atom forms inversion-symmetric dimers, which are further lin...

The title compound, C16H12N2O, exists in the crystalline state as the 5-imino-3,4-di-phenyl--1H-pyrrol-2-one tautomer. The dihedral angles between the pyrrole and phenyl rings are 35.3 (2) and 55.3 (2)°. In the crystal, inversion dimers linked by pairs of N-H⋯N hydrogen bonds generate a graph-set motif of R 2 (2)(8) via N-H⋯N hydrogen bonds.

The title compound, C(14)H(14)N(2)O, exists as the enol-imine tautomer. A strong intra-molecular hydrogen bond between O and N atoms forms a six-membered ring with an S(6) graph-set motif, which is approximately coplanar with the phenol ring, the inter-planar angle being 3.4 (3)°. In the crystal, inter-molecular C-H⋯O hydrogen bonds and N-H⋯π inter-actions link the mol-ecules into infinite chai...

(RS)-(±)-2-Methoxy-carbonyl-3-tropinone is an important inter-mediate for the preparation of cocaine and its derivatives. The molecule in the title compound, C(10)H(16)NO(3) (+)·C(4)H(5)O(6) (-), is present as the enol tautomer. The six-membered ring adopts a half boat conformation, and the five-membered ring a slightly distorted envelope conformation. There are intra- and inter-molecular hydro...

Dihydropteridine reductase has been obtained from sheep liver in essentially homogeneous form. The enzyme exists as a dimer of molecular weight 41,000 to 42,800. The subunit molecular weight has been determined to be 21,300. In the presence of the quinonoid tautomer of either dihydrobiopterin or dihydro-6,7-dimethylpterin, DPNH is a better substrate than TPNH. Evidence indicates that the activi...

We demonstrate, for what we believe is the first time, recording of a femtosecond image hologram by illumination with a single pair of high-intensity femtosecond pulses in a broad inhomogeneous bandwidth spectral hole-burning material consisting of a polymer film doped with anthraceno-phthalocyanine dye molecules. High efficiency of spectral hole burning is achieved by preillumination of the sa...

The title mol-ecule, C(32)H(24)N(2)O(2), has a crystallographically imposed inversion centre and exists in the crystal as an enol-imine tautomer. The mol-ecular structure is stabilized by two strong intra-molecular O-H⋯N hydrogen bonds. The dihedral angles between the central benzene ring and the mean planes of the phenyl substituents are 59.99 (1) and 62.79 (2)°. In the crystal, the mol-ecules...