1,3-Bis-aminooxy propane

A density functional theory study of the cleavage of a DNA model [p-nitrophenyl methyl phosphate (2)] and two RNA models [p-nitrophenyl 2-hydroxypropyl phosphate (3) and phenyl 2-hydroxypropyl phosphate (4)] promoted by the dinuclear Zn((II)) complex of 1,3-bis(1,5,9-triazacyclododec-1-yl)propane formulated with a bridging methoxide (1a) was undertaken to determine possible mechanisms for the transesterification processes that are consistent with experimental data. The initial substrate-bound state of 2:1a or 3:1a has the two phosphoryl oxygens bridging Zn((II))1 and Zn((II))2. For each of 2 and 3, four possible mechanisms were investigated, three of which were consistent with the overall free energy for the catalytic cleavage step for each substrate. The computations revealed various roles for the metal ions in the three mechanisms. These encompass concerted or stepwise processes, where the two metal ions with associated alkoxy groups [Zn((II))1:((-)OCH3) and Zn((II))1:((-)O-propyl)] play the role of a direct nucleophile (on 2 and 3, respectively) or where Zn((II))1:((-)OCH3) can act as a general base to deprotonate an attacking solvent molecule in the case of 2 or the attacking 2-hydroxypropyl group in the case of 3. The Zn((II))2 ion can serve as a spectator (after exerting a Lewis acid role in binding one of the phosphates' oxygens) or play active additional roles in providing direct coordination of the departing aryloxy group or positioning a hydrogen-bonding solvent to assist the departure of the leaving group. An important finding revealed by the calculations is the flexibility of the ligand system that allows the Zn-Zn distance to expand from ~3.6 Å in 1a to over 5 Å in the transforming 2:1a and 3:1a complexes during the catalytic event.

1,2,3-Trichloropropane (TCP) is an emerging groundwater pollutant and suspected human carcinogen. TCP, a recalcitrant contaminant, has been detected in the subsurface near TCP manufacture facilities and many superfund sites. Considering the toxicity and the occurence of TCP, there is a need to seek for cost-effective treatment technologies for TCP-contaminated sites. This paper investigated TCP biodegradation by propane-oxidizing bacteria (PrOB) which are known to express propane monooxygenase (PrMO). PrMO can cometabolically degrade many different contaminants. Four PrOB, Rhodococus jostii RHA1, Mycobacterium vaccae JOB5, Rhodococcus rubber ENV425 and one isolate Sphingopyxis sp. AX-A were examined for their ability to degrade TCP. All the four PrOB resting cells were able to degrade TCP. Strain JOB5 exhibited the best TCP degradation ability (vinitial = 9.7 ± 0.7 μg TCP (mg protein)-1h-1). No TCP was degraded in the presence of acetylene (an inhibitor for PrMO), suggesting that PrMO might be responsible for TCP degradation. Furthermore, competitive inhibition was observed between propane and TCP, and between trichloroethylene (TCE) and TCP.

The novel water soluble bidentate phosphine ligand 1,3-bis(di-2-pyridylphosphino)propane (d2pypp) has been synthesized by a convenient route involving treatment of 2-pyridyllithium with Cl(2)P(CH(2))(3)PCl(2) and isolation in crystalline form as the hydrochloride salt. The synthesis of the precursor Cl(2)P(CH(2))(3)PCl(2) has been optimized by the use of triphosgene as the chlorinating agent. The 2 : 1 and 1 : 2 AuCl : d2pypp adducts have been synthesized and characterized by NMR spectroscopy and single crystal X-ray studies, and shown to be of the form (AuCl)(2)(mu-d2pypp-P,P') and [Au(d2pypp-P,P')(2)]Cl(.3.75H(2)O), respectively. The latter is more lipophilic than analogous 1 : 2 adducts of gold(I) chloride with the diphosphine ligands 1,2-bis(di-n-pyridylphosphino)ethane (dnpype) for n = 2, 3 and 4, based on measurement of the n-octanol-water partition coefficient (log P = -0.46). A single crystal structure determination of the 1 : 2 Au(I) complex of the 3-pyridyl ethane ligand shows it to be of the form [Au(d3pype-P,P')(2)]Cl.5H(2)O. The in vitro cytotoxic activity of [Au(d2pypp)(2)]Cl was assessed in human normal and cancer breast cells and selective toxicity to the cancer cells found. The significance of these results to the antitumour properties of chelated 1 : 2 Au(I) diphosphine complexes is discussed.