Anion templating from a silver(i) dithiophosphate 1D polymer forming discrete cationic and neutral octa- and decanuclear silver(i) clusters.

We report on a Ag5 coordination polymer and discrete Ag8 and Ag10 dithiophosphate clusters. The cluster formation and structures were affected by the stoichiometric control of the M : L molar ratios used. The cluster [Ag5{S2P(O(i)Pr)2}4]n(PF6)n, , is a monomeric unit within a coordination polymer formed through the reaction between [Ag(CH3CN)4]PF6 and the dithiophosphate ligand, [S2P(O(i)Pr)2](-), used in a M : L molar ratio of 5 : 4. All other clusters formed in the study are discrete units with encapsulated anions within the metal framework. The clusters [Ag8(X){S2P(O(i)Pr)2}6](PF6) (X = F, , Cl, , Br, ) are all cationic and contain monoanionic halogens. The related cluster [Ag8(H/D){S2P(O(i)Pr)2}6](PF6) contains either a hydride or a deuteride ion, and , respectively. The cluster [Ag8(S){S2P(O(i)Pr)2}6], , is neutral due to the di-anionic nature of the encapsulated sulfide anion. Clusters were all formed by reacting [Ag(CH3CN)4]PF6 and [S2P(O(i)Pr)2](-) in a M : L molar ratio of 8 : 6 and stirring for 1 h in THF; thereafter the respective anions (one equiv.) were added in situ. The cluster [Ag10(I)4{S2P(O(i)Pr)2}6], , is also neutral due to the charge balancing of the additional metal and halogen. In this case the M : L : X molar ratio was 10 : 6 : 4. All new clusters were characterized by (1)H and (31)P NMR, and elemental analysis, and , , were characterized by single crystal X-ray diffraction.

Influence of fluorocarbon flat-membrane hydrophobicity on carbon dioxide recovery.

The influence of hydrophobicity in flat-plate porous poly(vinylidene fluoride) (PVDF) and expended polytetrafluoroethylene (PTFE) membranes on CO(2) recovery using aqueous solutions of piperazine (PZ) and alkanolamine is examined. Experiments were conducted at various gas flow rates, liquid flow rates, and absorbent concentrations. The CO(2) absorption flux increased with increasing gas flow rates and absorbent concentrations. When using 2-amino-2-methyl-1-propanol (AMP) or AMP+PZ aqueous solution as absorbent, this process was dominantly governed by gas film layer diffusion and membrane diffusion. The diffusion resistance of the membrane phase was only important when using N-methyldiethanolamine as the sole absorbent. The water contact angle increased initially with increasing plasma working power and reached at steady state value of 155 degrees beyond 100 W. The elemental fluorine-to-carbon ratio (F/C) and water contact angle of the PVDF membrane increased with increasing treatment time and reached a plateau after 5min of CH(4) plasma (100 W). Increases in the CO(2) absorption fluxes of 7% and 17% were observed for plasma-treated PVDF membranes in comparison to non-treated PVDF and PTFE, respectively, when using 1M AMP as absorbent. The membrane mass transfer coefficient, k(m), for plasma-treated PVDF membranes increased from 2.1 x 10(-4) to 2.5 x 10(-4)ms(-1). Membrane durability was greatly improved by CF(4) plasma treatment (100 W/5 min) and comparable to that of PTFE membranes.