Distinguishing Isomeric Cyclobutane Thymidine Dimers by Ion Mobility and Tandem Mass Spectrometry.

Irradiation of the major conformation of duplex DNA found in cells (B form) produces cyclobutane pyrimidine dimers (CPDs) from adjacent pyrimidines in a head-to-head orientation () with the C5 substituents in a cis stereochemistry. These CPDs have crucial implications in skin cancer. Irradiation of G-quadruplexes and other non-B DNA conformations in vitro produces, however, CPDs between nonadjacent pyrimidines in nearby loops with syn and head-to-tail orientations () with both cis and trans stereochemistry to yield a mixture of six possible isomers of the T=T dimer.

Fast Protein Footprinting by X-ray Mediated Radical Trifluoromethylation.

Synchrotron radiolysis generates hydroxyl radicals (OH) that are successful footprinting reagents. Here, we describe a new reagent for the synchrotron platform, the trifluoromethyl radical (CF). The radical is produced by OH displacement of CF from sodium triflinate (Langlois reagent).

Protonated -Alkyl-2-nitroanilines Undergo Intramolecular Oxidation of the Alkyl Chain upon Collisional Activation.

The collisional activation of protonated -propyl-2-nitroaniline obtained by electrospray ionization shows two major competitive dissociation pathways: the elimination of the elements of propionic acid, [M + H - CHO] to give an 107 ion, and of the elements of ethanol, [M + H - CHO] to give an 135 ion. The mechanistic study reported here addresses these unusual fragmentations to reveal that both occur via a common intermediate formed by the transfer of an oxygen atom from the nitro group to the first carbon atom of the propyl group, allowing elimination of propionic acid and (HO + ethene), respectively. The corresponding loss of CHO does not occur when the propyl group is replaced by an ethyl group, but elimination of the elements of propanol does occur when propyl is replaced by a butyl group.

McLafferty-type rearrangement of protonated N-[nicotinoyl]phenylethyl amines and consequent elimination of styrene.

Rationale: McLafferty rearrangements occur in radical cations of molecules containing a carbonyl group and a γ hydrogen atom but are not common in the [M+H](+) ions of carbonyl compounds. We propose to investigate the collision-induced dissociation (CID) of the [M+H](+) ions of nicotinoyl and picolinoyl amides of 1- and 2-phenylethylamines to explore the possibility of McLafferty-type rearrangement.

Methods: The compounds for study were synthesized by the reaction of methyl nicotinate or methyl picolinate with 1- and 2-phenylethylamines.

Exploring the Catalytic Potential of ZIF-90: Solventless and Co-Catalyst-Free Synthesis of Propylene Carbonate from Propylene Oxide and CO.

Reported is the application of ZIF-90, which is a highly porous zeolitic imidazolate framework, as a novel catalyst for the cycloaddition of propylene oxide (PO) with CO in the absence of co-catalysts and solvents under moderate reaction conditions. The effects of various reaction parameters were investigated. The activity of ZIF-90 was compared with that of various metal-organic-framework (MOF)-based catalysts for the cycloaddition of PO with CO .