Biomedical subjects
Publications and source records attributed to K A Udachin.
The study of solid p-tert-butylcalix[4]arene and its compounds with a variety of techniques has provided a good understanding of the versatility of this host molecule, how to induce a number of distinct host-guest motifs, its molecular recognition properties, the complex phase relationships and unique properties such as gas adsorption without having obvious channels.
The mixed-metal cluster complexes [Ru(4)(CO)(12)Pt(CO)PPh(3)(mu(4)-PR)] [R = N(i)Pr(2) (1), F (3)] were formed by capping the Ru(3)P face of the nido clusters [Ru(4)(CO)(13)(mu(3)-PR)] with the labile Pt(0) reagent [(eta(2)-C(2)H(4))Pt(PPh(3))(2)]. The aminophosphinidene complex 1 undergoes acid hydrolysis to yield the PO complex [Ru(4)(CO)(12)Pt(CO)PPh(3)(mu(4)-PO)][H(2)N(i)Pr(2)] (4). The fluorophosphinidene cluster 3 reacts with ethanol to form the alkoxyphosphinidene complex [Ru(4)(CO)(12)Pt(CO)PPh(3)(mu(4)-POEt)] (5). Comparison of spectroscopic and structural data for clusters 1, 3, 4, and 5 reveals the remarkable effects of the mu(4)-phosphinidene and phosphorus monoxide ligands on cluster bonding.
Interactions between hydrophobic groups in water, as well as biomolecular hydration more generally, are intimately connected to the structure of liquid water around hydrophobic solutes. Such considerations have focused interest on clathrate hydrates: crystals in which a hydrogen-bonded network of water molecules encages hydrophobic guest molecules with which the water interacts only by non-directional van der Waals forces. Three structural families of clathrate hydrates have hitherto been recognized: cubic structure I (2M(S)-6M(L) x 46H2O), cubic structure II (16M(S) x 8M(L)-136H2O) and hexagonal structure H (M(L) x 3M(S) x 2M(S) x 34H2O) hydrates (here M(L) and M(S) are the hydrophobic guest sites associated with large and small cavities, respectively). Here we report a new hydrate structure: 1.67 choline hydroxide-tetra-n-propylammonium fluoride x 30.33H2O. This structure has a number of unusual features; in particular the choline guest exhibits both hydrophobic and hydrophilic modes of hydration. Formally the structure consists of alternating stacks of structure H and structure II hydrates, and might conceivably be found in those settings (such as seafloor deposits over natural-gas fields) in which clathrate hydrates form naturally.