Helical foldamers as hosts for rod-like guests

How many guests, what sort of hosts?

To the Editor: Lansing et al. (1) offer an intriguing approach to the prehistory of the island of Sumba. There is at least one critical f law in the reasoning used, the assumption that the languages of Sumba form a subgroup, being all derived from a single ancestral language, Proto-Sumba. The comparative method used by the authors allows us to subgroup languages together if two criteria are met...

Partially-methylated amyloses as effective hosts for inclusion complex formation with polymeric guests.

Partially 2,3-O-methylated amyloses efficiently form inclusion complexes with polytetrahydrofuran and poly(epsilon-caprolactone) by simply mixing them in DMSO-H(2)O (1 : 9) solution, in contrast to the case of the parent amylose in which the corresponding inclusion complexes are only slightly formed.

Diastereotopic fluorine substituents as 19F NMR probes of screw-sense preference in helical foldamers.

Ligating simple amino alcohol or amino ester monomers containing enantiotopic fluorine substituents to the C-terminus of a helical peptide places the fluorine atoms in diastereotopic environments, and gives two distinct and easily identifiable signals in the (19)F NMR spectrum. In the case of a dynamically inverting helix built from achiral monomers, the chemical shift separation between the (1...

The design of molecular hosts, guests, and their complexes.

The origins, definitions, tools, and guiding principles of host-guest chemistry are developed. Perching, nesting, and capsular complexes are exemplified through molecular model and crystal structure comparisons. The degree of preorganization of a host for binding is a central determinant of its binding power. Complementarity of binding site placement in host and guest is a central determinant o...

Poly(iminomethylenes): Rigid Rod Helical Polymers