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Solution NMR spectroscopy and solid state X-ray crystallography was employed to understand the structure of the helical aromatic oligoamide foldamer which encapsulates tartaric acid with exceptional affinity, selectivity, and diastereoselectivity. The results provide insight into the role of hydrogen bonds between the hydroxyl and carboxylic acid groups of tartaric acid and the inner wall of the helically folded capsule which completely surrounds the guest and insulates it from the solvent.

The effect of the ortho alkylation of perylene bisimides on the alignment and self-assembly properties has been studied. It was found that the dichroic properties of perylene bisimides in a liquid crystal host can be reversed with a single synthetic step by ortho alkylation. Furthermore, a solvent-induced growth of ultralong organic n-type semiconducting fibrils from non- ortho-alkylated perylene bisimide was observed. Ortho substitution of the perylene bisimide core alters the mode of fibrillar growth, leading to isotropic crystallization. [ABSTRACT FROM AUTHOR]

The synthesis of quinoline-derived helically folded aromatic oligoamides functionalized by various chiral functions at their N-terminus is reported. When a (1S)-(-)-camphanyl moiety was introduced, it was found that helix handedness was completely shifted to right-handed helicity (de > 99%), in both protic and nonprotic solvents. The absolute helical sense and the de values were unambiguously characterized by using 1H NMR, circular dichroism (CD), and X-ray crystallography. The crystal structure of these compounds allowed us to propose a rationale for the efficiency of helix handedness induction based on a combination of steric factors and intramolecular hydrogen bonding. [ABSTRACT FROM AUTHOR]

Materials showing rapid intramolecular energy transfer and polarization switching are of interest for both their fundamental photophysics and potential for use in real-world applications. Here, we report two donor-acceptor-donor triad dyes based on perylene-bisimide subunits, with the long axis of the donors arranged either parallel or perpendicular to that of the central acceptor. We observe rapid energy transfer (<2 ps) and effective polarization control in both dye molecules in solution. A distributed-dipole Förster model predicts the excitation energy transfer rate for the linearly arranged triad but severely underestimates it for the orthogonal case. We show that the rapid energy transfer arises from a combination of through-bond coupling and through-space transfer between donor and acceptor units. As they allow energy cascading to an excited state with controllable polarization, these triad dyes show high potential for use in luminescent solar concentrator devices.

This communication describes the development of conformationally constrained unnatural aromatic amino acids, constructed on rigid backbone wherein the carboxyl and amino groups project in two dimensions (planes) on the aromatic framework. Such a feature offers the possibility of design and development of conformationally ordered synthetic oligomers with intriguing structural architectures distinct from those classically observed. Furthermore, such amino acids will have the potential to extend the conformational space available for foldamer design with diverse backbone conformation and structural architectures.

This communication demonstrates the utility of inherently rigid building blocks such as 1,1'-spirobi(indane) for generating conformationally ordered synthetic oligomers with structural architectures distinct from those classically observed.

In the molecule of the title compound, C(18)H(32)N(2)O(4), the central bicyclo-[3.3.0]octane (octa-hydro-penta-lene) has a rigid ring junction. Both rings of the bicyclo-[3.3.0]octane unit adopt an envelope conformation, and the flexible tert-butyl-carbamoyl side chains each have an extended conformation. Such a constrained bicyclo-[3.3.0]octane aliphatic template is of inter-est with respect to the design of novel self-assembling motifs. Mol-ecules related by c-glide symmetry are linked via inter-molecular N-H⋯O hydrogen bonds, forming a two-dimensional layer structure. Neighboring layers are weakly associated along the a axis due to the close approach of the tert-butyl-carbamoyl groups (2.55 Å).