Contents

12 March 1993
Vol 259, Issue 5101

About The Cover

Representation of chiral, intertwined double helices in a portion of the vanadium phosphate [(CH3)2NH2-K4[V10O10(H2O)2(OH)4(PO4)7]·4H2O, a complicated inorganic solid that self-assembles from structurally simpler reactants. The two different colors represent the two types of intertwined, crystallographically independent spirals that are composed of vanadium oxo pentamers bonded together with P5+ cations. See page 1596. New developments in chemistry are featured in a special section of this issue beginning on page 1552. [Image: Yoko Ozawa and Brad Gianulis, generated by CAChe software, Tektronix]