The structure of the interface generated by a spread layer of beta-casein on an aqueous colloidal poly(silicic) acid subphase is described. The results are compared with data for the protein alone spread at the air/water interface and the silicate solution. Films develop at the air-solution interface and a strong pH dependence of the interaction causing this is demonstrated. Reflectometry with X-rays and neutrons was used to probe the interaction as a function of subphase pH and film compression. Film thickness, tau/A, scattering length density, rho/A(-2), water volume fraction, phi(w), and surface coverage, Gamma/mg m(-2), were used to quantify the interfacial structure. Where possible, the X-ray and neutron data sets were co-refined enabling phi(w) to be evaluated without assumption regarding the protein density. At pH 5-7, strong protein-silicate interaction occurred, the interface comprising three regions: a discrete protein upper layer on top of a 15 +/- 2 A layer of silicated material followed by a diffuse layer that extended into the subphase.
A series of mixed-ligand–titanium complexes is reported which incorporate a tridentate N-methyldiethoxoamine (mdea) ligand in conjunction with chelating diolate ligand. X-ray crystal structures of the complexes [Ti(mdea) (O-O)]2 (where O-O = OC(CH3)2C(CH3)2O (1), OC(C2H5)2C(C2H5)2O (2), OC(CH3)2CH2CH(CH3)O (3), and OC(CH3)2CH2C(CH3)2O (4)) show them to exist as dimers in the solid state, with one arm of the aminodialkoxy ligand μ-bridging two titanium centres. Solution-state 1H and 13C NMR studies concur with the solid-state structures of (1)–(4) at low temperature. The room-temperature spectra of (3) and (4) suggest that bridging bond scission and reformation occurs increasing the apparent symmetry of the complexes. Complexes (3) and (4) dissociate into monomers in the vapour phase. The influence of the diolate ligand on the bridging bond strengths is discussed.
The title compound, bis(2,2'-methyliminodiethanolato)-1kappa(3)O,N,O';3kappa(3)O,N,O'-di-micro(3)-propane-1,3-diolato-1:2:3kappa(8)O:O,O':O'-micro-propane-1,3-diolato-1:3kappa(2)O:O'-propane-1,3-diolato-2kappa(2)O,O'-trititanium(IV), [Ti(3)(C(5)H(11)NO(2))(2)(C(3)H(6)O(2))(4)], has four 1,3-propanediolate ligands binding in three different modes. Two ligands chelate adjacent Ti atoms with normal micro(3)-O bridges, giving typical edge-sharing of the Ti distorted octahedra, one chelating to the central Ti atom with no micro-bridging, and the other spanning the cluster, binding only to the outermost Ti atoms. The two methyliminodiethanolate ligands each coordinate to the outer Ti atoms via their N and two O atoms. The Ti-O bond lengths range, in a self-consistent fashion, from 1.816 (2) to 2.082 (2) A, while the average Ti-N distance is 2.391 (3) A.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.