Metal-nucleic acid cages.

Metal-nucleic acid cages are a promising new class of materials. Like metallo-supramolecular cages, these systems can use their metals for redox, photochemical, magnetic and catalytic control over encapsulated cargo. However, using DNA provides the potential to program pore size, geometry, chemistry and addressability, and the ability to symmetrically and asymmetrically position transition metals within the three-dimensional framework. Here we report the quantitative construction of metal-DNA cages, with the site-specific incorporation of a range of metals within a three-dimensional DNA architecture. Oligonucleotide strands containing specific environments suitable for transition-metal coordination were first organized into two DNA triangles. These triangles were then assembled into a DNA prism with linking strands. Metal centres were subsequently incorporated into the prisms at the pre-programmed locations. This unprecedented ability to position transition metals within a three-dimensional framework could lead to metal-DNA hosts with applications for the encapsulation, sensing, modification and release of biomolecules and nanomaterials.

Rearrangement of molybdocene tetraoxotetrasulfide Cp2MoS4O4 to Give [(Cp2MoS2H)2](HSO4)2: a novel proton-stabilized molybdocene disulfide dimer.

Cp(2)MoS(4), 1, in CH(2)Cl(2) undergoes extensive oxidation by m-CPBA at -78 degrees C to give a 1,1,4,4-tetroxide, 2 (59%). Tetraoxide 2 rearranges at room temperature to give an unusual sulfur-atom protonated molybdocene disulfide dimer [(Cp(2)MoS(2)H)(2)](HSO(4))(2), 3. Crystal data for 3 are P, a = 6.751(2) Angstroms, b = 9.865(4) Angstroms, c = 11.549(5) Angstroms, alpha = 109.95(3) degrees, beta = 96.11(3) degrees, gamma = 108.22(3) degrees, V = 666.9(4) Angstroms(3), and Z = 1. The dimer was also obtained directly when the oxidation was conducted at 0 degree C in DMF. Under basic conditions, the dimer is cleaved to give molybdocene disulfide Cp(2)MoS(2), while treatment of the latter with acid converts it to the dimer 3.

Insertion of SO(2) into the S-S bond of Cp(2)MoS(2) and Cp(2)MoS(2)O to give molybdocene dithiosulfate and bis(O-alkylthiosulfates).

Cp(2)MoS(2), 3, reacts with SO(2) in CH(2)Cl(2)/EtOH mixtures to give Cp(2)MoS(3)O(2), 4, wherein the SO(2) has inserted into the S-S bond to give a dithiosulfate ligand. Crystal data for 4: P2(1)/n, a = 7.6782(6) A, b = 14.580(3) A, c = 10.2730(10) A, beta = 92.04(1) degrees, V = 1149(3) A(3), Z = 4. Cp(2)MoS(2)O, 5, reacts with SO(2) in CH(2)Cl(2) to give low yields of 4 plus other identified products. 5 reacts with SO(2) in MeOH and EtOH to give the corresponding bis(O-alkylthiosulfate), 6a and 6b, respectively. Crystal data for 6a: P 1 macro, a = 8.3226(13) A, b = 8.4736(11) A, c = 12.382(2) A, alpha = 87.803(11) degrees, beta = 77.758(11) degrees, gamma = 86.383(12) degrees, V = 851.4(2) A(3), Z = 2.