This manuscript describes a single-crystal-tosingle-crystal polymerization of the dihydrate of diacetylene 1 (1•2H 2 O) to give an unusual polydiacetylene (PDA) structure that consists of aligned nanotubes, with each covalently bonded nanotube having two parallel PDA chains that run parallel down opposite sides of a channel defined by the macrocycle. Each PDA nanotube is connected with four other columns via amide hydrogen bonds with an N-(H)•••O distance of 2.888(4) Å. Such well-ordered polymers should display quasi-one-dimensional electronic structures and may be of interest for the formation of highly conductive organic materials. We obtained the 1•2H 2 O form in bulk, which was polymerized by heating. Powder X-ray diffraction suggests that bulk PDA powder is single phase and displays a similar structure as the PDA single crystals. Furthermore, we showed that PDA crystals absorbed I 2 vapor. We believe that this unique PDA structure, which is amenable to property control via adsorbed guests, will be an attractive one for investigating charge-transfer doping in PDA-based organic electronic materials. We also observed two additional crystal forms, including 1•MeOH, which also shows a columnar assembly, and a tetrahydrate 1•4H 2 O that shows water tetramers that link four cycles into a 2D sheet structure.

Single crystals of five new uranyl oxychlorides exhibiting novel layer topology, CCIs, chain structures, and/or luminescence were grown from molten chlorides. A comprehensive CCI classification is presented.

Single crystals of MnUO 4 , FeUO 4 , and NiU 2 O 6 were grown for the first time. The use of chloride fluxes facilitated the crystal growth. MnUO 4 , a hexavalent uranium compound, crystallizes in the orthorhombic space group, Imma, with a = 6.6421(19) Å, b = 6.978 (2) Å, and c = 6.748 (2) Å, and exhibits typical uranyl, UO 2 2+ , coordination. FeUO 4 and NiU 2 O 6 contain pentavalent uranium and are structurally related, exhibiting threedimensional connectivity. FeUO 4 crystallizes in the orthorhombic space group, Pbcn, with a = 4.8844(2) Å, b = 11.9328(5) Å, c = 5.1070(2) Å. NiU 2 O 6 crystallizes in the trigonal space group, P321, with a = 9.0148(3) Å, c = 5.0144(3) Å.

Single crystals of two uranium silicates, Cs2USiO6 and Rb2USiO6, have been grown from molten fluoride fluxes and structurally characterized by single-crystal X-ray diffraction. Cs2USiO6 crystallizes in the body-centered orthorhombic space group, Immm, with a = 8.5812(4) Å, b = 13.0011(6) Å, and c = 13.8811(7) Å. The size of Rb is slightly too small to fit into this structural framework without effecting slight structural changes that result in a 6-fold superstructure. Sharp satellite peaks were observed in the single-crystal X-ray diffraction data, indicating the existing of a superstructure. The crystals were examined by electron diffraction, the results of which suggest that the structure can be thought of as the Immm isotype (a = 8.4916(6) Å, b = 12.6678(9) Å, and c = 13.5077(9) Å) on average, with an approximately 6-fold superstructure along the c axis. The materials were further characterized by UV-vis reflectance spectroscopy.

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