THE recent synthesis of silica-based mesoporous materials by the cooperative assembly of periodic inorganic and surfactant-based structures has attracted great interest because it extends the range of molecular-sieve materials into the very-large-pore regime. If the synthetic approach can be generalized to transition-metal oxide mesostructures, the resulting nanocomposite materials might find applications in electrochromic or solid-electrolyte devices, as high-surface-area redox catalysts and as substrates for biochemical separations. We have proposed recently6 that the matching of charge density at the surfactant/inorganic interfaces governs the assembly process; such co-organization of organic and inorganic phases is thought to be a key aspect of biomineralization. Here we report a generalized approach to the synthesis of periodic mesophases of metal oxides and cationic or anionic surfactants under a range of pH conditions. We suggest that the assembly process is controlled by electrostatic complementarity between the inorganic ions in solution, the charged surfactant head groups and—when these charges both have the same sign—inorganic counterions. We identify a number of different general strategies for obtaining a variety of ordered composite materials

The organization of cationic or anionic organic and inorganic molecular species to produce three-dimensional periodic biphase arrays is described. The approach uses cooperative nucleation of molecular inorganic solution species with surfactant molecules and their assembly at low temperatures into liquid-crystal-like arrays. The organic/inorganic interface chemistry makes use of four synthesis routes with (S+I-), (S-I+), (S+X-I+), and (S-M+I-) direct and mediated combinations of surfactant (cationic S+, anionic S-) and soluble inorganic (cationic I+, anionic I-) molecular species. The concepts can be widely applied to generate inorganic oxide, phosphate or sulfide framework compositions. Distinct lamellar, cubic silica mesophases were synthesized in a concentrated acidic medium (S+X-I+), with the hexagonal and the cubic phases showing good thermal stability. For the hexagonal mesostructured silica materials high BET surface areas (>1000 m₂/g) are found. Hexagonal tungsten(V1) oxide materials were prepared in the presence of quaternary ammonium surfactants in the pH range 4-8. Cubic (Ia3d) and hexagonal antimony(V) oxides were obtained by acidifying (pH = 6-7) homogeneous solutions of soluble Sb(V) anions and quaternary ammonium surfactants at room temperature (S+I-). Using anionic surfactants, hexagonal and lamellar lead oxide mesostructures were found (S-I+). Crystalline zinc phosphate lamellar phases were obtained at low synthesis temperatures (4°C) and lamellar sulfide phases could be also readily generated at room temperature. The synthesis procedure presented is relevant to the coorganization of organic and inorganic phases in biomineralization processes, and some of the biomimetic implications are discussed

A model that makes use of the cooperative organization of inorganic and organic molecular species into three dimensionally structured arrays is generalized for the synthesis of nanocomposite materials. In this model, the properties and structure of a system are determined by dynamic interplay among ion-pair inorganic and organic species, so that different phases can be readily obtained through small variations of controllable synthesis parameters, including mixture composition and temperature. Nucleation, growth, and phase transitions may be directed by the charge density, coordination, and steric requirements of the inorganic and organic species at the interface and not necessarily by a preformed structure. A specific example is presented in which organic molecules in the presence of multiply charged silicate oligomers self-assemble into silicatropic liquid crystals. The organization of these silicate-surfactant mesophases is investigated with and without interfacial silicate condensation to separate the effects of self-assembly from the kinetics of silicate polymerization.

A new chemical class of potent DPP-4 inhibitors structurally derived from the xanthine scaffold for the treatment of type 2 diabetes has been discovered and evaluated. Systematic structural variations have led to 1 (BI 1356), a highly potent, selective, long-acting, and orally active DPP-4 inhibitor that shows considerable blood glucose lowering in different animal species. 1 is currently undergoing clinical phase IIb trials and holds the potential for once-daily treatment of type 2 diabetics.

The structure of the heme o prosthetic group of Escherichia coli quinol oxidase (cytochrome o oxidase) has been unambiguously determined by preparation and characterization of its iron-free derivative porphyrin o dimethyl ester, or dimethyl 2,7,12,18-tetramethyl-3-[(4£,8£)-l -hydroxy-5,9,13-trimethyltetradeca-4,8,12-trienyl] -8-vinylporphine-13,17-dipropionate. The identity of this natural porphyrin dimethyl ester was established by 'H NMR, MS, IR, and RR spectroscopies as well as by comparisons with model compounds and the closely related porphyrin a dimethyl ester. The reliability of the structure determination was further strengthened by the isolation and characterization of the acetylated and dehydrated derivatives of porphyrin o.