Thermodynamics and Biological Properties of The Aqueous Solutions of New Gluco-Cationic Surfactants

Thermodynamic properties of aqueous solutions of newly synthesized compounds, namely, N-[2-(ƒÒ-D-glucopyranosyl) ethyl]-N,N-dimethyl-N-alkylammonium bromides with hydrophobic tails of 12 (C12DGCB) and 16 (C16DGCB) carbon atoms, determined as a function of concentration by means of direct methods, are reported here. Dilution enthalpies, densities, and sound velocities were measured at 298 K, allowing for the determination of apparent and partial molar enthalpies, volumes, and compressibilities. Changes in thermodynamic quantities upon micellization were derived using a pseudophase-transition approach. From a comparison with the corresponding acetylated compounds N-[2-(2,3,4,6-tetra-O-acetyl-ƒÒ-D-glucopyranosyl)- ethyl]-N,N-dimethyl-N-dodecylammonium bromide (C12AGCB) and N-[2-(2,3,4,6-tetra-O-acetyl-ƒÒ-D-glucopyranosyl) ethyl]-N,N-dimethyl-N-hexadecylammonium bromide (C16AGCB), the role played in the micellization process by the acetylated glycosyl moiety was inferred: it enhances the hydrophobic character of the molecule and lowers the change in enthalpy of micelle formation by about 1.5 kJ mol-1. By comparing the volume of C12DGCB with those of DEDAB and DTAB, the volumes taken up by the (ƒÒ-D-glucopyranosyl)ethyl and ƒÒ-D-glucopyranosyl groups were found to be 133 and 99 cm3 mol-1, respectively. Regarding the interaction with DPPC membranes, it seems that the sugar moiety of the hexadecyl deacetylated compound gives rise to hydrogen bonds with the oxygen atoms of the lipid phosphates, shifting the phase transition of DPPC from a bilayer gel to a bilayer liquid crystal to lower temperatures. C16AGCB induces significantly greater changes than C16DGCB in the structure of liposomes, suggesting the formation of domains. The interaction is strongly enhanced by the presence of water. Neither compound interacts strongly with DNA or compacts it, as shown by EMSA assays and AFM images. Only C16AGCB is able to deliver little DNA inside cells when coformulated with DOPE, as shown by the transient transfection assay. This might be related to the ability of C16AGCB to form surfactant-rich domains in the lipid structure

Sensitive and selective chromogenic sensing of carbon monoxide via reversible axial CO coordination in binuclear rhodium complexes

The study of probes for CO sensing of a family of binuclear rhodium(II) compounds of general formula [Rh 2{(XC 6H 3)P(XC 6H 4)} n(O 2CR) 4-n]·L 2 containing one or two metalated phosphines (in a head-to-tail arrangement) and different axial ligands has been conducted. Chloroform solutions of these complexes underwent rapid color change, from purple to yellow, when air samples containing CO were bubbled through them. The binuclear rhodium complexes were also adsorbed on silica and used as colorimetric probes for "naked ey" CO detection in the gas phase. When the gray-purple colored silica solids containing the rhodium probes were exposed to air containing increasing concentrations of CO, two colors were observed, in agreement with the formation of two different products. The results are consistent with an axial coordination of the CO molecule in one axial position (pink-orange) or in both (yellow). The crystal structure of 3·(CO) ([Rh 2{(C 6H 4)P(C 6H 5) 2} 2(O 2CCF 3) 2]·CO) was solved by single X-ray diffraction techniques. In all cases, the binuclear rhodium complexes studied showed a high selective response to CO with a remarkable low detection limit. For instance, compound 5· (CH 3CO 2H) 2 ([Rh 2{(m- CH 3C 6H 3)P(m-CH 3C 6H 4) 2} 2(O 2CCH 3) 2]· (CH 3CO 2H) 2) is capable of detection of CO to the "naked ey" at concentrations as low as 0.2 ppm in air. Furthermore, the binding of CO in these rhodium complexes was found to be fully reversible, and release studies of carbon monoxide via thermogravimetric measurements have also been carried out. The importance of the silica support for the maintenance of the CO-displaced L ligands in the vicinity of the probes in a noninnocent manner has been also proved. © 2011 American Chemical Society.The authors wish to express their gratitude to the Spanish Ministerio de Ciencia y e Innovacion (projects MAT2009-14564-C04-01 and CTQ2009-14443-C02-02) and Generalitat Valenciana (project PROMETEO/2009/016) for their support. MEM is grateful to the Spanish Ministerio de Ciencia e Innovacion for an FPU grant.Moragues Pons, ME.; Esteban Moreno, J.; Ros-Lis, JV.; Martínez Mañez, R.; Marcos Martínez, MD.; Martínez, M.; Soto Camino, J.... (2011). Sensitive and selective chromogenic sensing of carbon monoxide via reversible axial CO coordination in binuclear rhodium complexes. Journal of the American Chemical Society. 133:15762-15772. https://doi.org/10.1021/ja206251rS157621577213