Single crystals of the orthorhombie form of hexatriacontane C3sH~4 have been shown to have space group Pca21 with unit-cell dimensions a ----7.42, b ----4.96, c ----95.14 /~. The crystal structure has been determined from Fourier syntheses of the electron density projected down the three principal crystallographic axes and from observations of the agreement between observed and calculated structure factors. The molecular chains are regular and periodic within experimental error, with a C-C bond length of 1.533 A and a zigzag bond angle of 112 °. The side-by-side packing of chains is identical with that found in the monoclinie form and in polythene. Intermolecular distances are given and discussed briefly in relation to the polymorphism, the stability and the anisotropic thermal vibrations and expansion coefficients of long chain hydrocarbons.

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a Herein the first example of a bimetallic coiled coil featuring a lanthanide binding site is reported, opening opportunities to exploit the attractive NMR and photophysical properties of the lanthanides in multi metallo protein design. In our efforts to fully characterise the system we identified for the first time that lanthanide binding to such sites is pH dependent, with optimal binding at neutral pH, and that the double AsnAsp site is more versatile in this regard than the single Asp site. Our second site featured the structural HgCys 3 site, the chemistry of which was essentially unaltered by the presence of the lanthanide site. In fact, both metal binding sites within the hetero bimetallic coiled coil displayed the same properties as their mononuclear single binding site controls, and operated independently of each other. Finally, pH can be used as an external trigger to control the binding of Hg(II) and Tb(III) to the two distinct sites within this coiled coil, and offers the opportunity to "activate" metal binding sites within complex multi metallo and multi-functional designs.

The hydration state of designed metal binding sites in coiled coils can be tuned by terminal second sphere residues.