A MOLECULAR VERNIER

The spontaneous organization of individual molecules into complex asse mblies with precise dimension is essential to biological systems. The ''vernier'' mechanism is one of only a very few ways (Figure 1) propos ed for regulating the size of the resulting aggregate, but no instance of a vernier's operation has yet been demonstrated in either a biolog ical or nonbiological setting. The first example of a molecular vernie r is now described (Figures 2 and 3): Three molecules of a dicarboxyla te combine with two molecules of a triguanidinium to give a pentamer o f predetermined dimension. (C) 1998 Elsevier Science Ltd. All rights r eserved.