Poly(1-vinylimidazole) with a trimethoxysilyl terminal group (Im n ) was synthesized by telomerization of 1-vinylimidazole. The degree of polymerization (n) was determined by 1H NMR to be 18. The Im18 with reactive silane terminal group was grafted directly onto nanosize magnetic particles (maghemite, γ-Fe2O3) through siloxane bonds to produce polymer-grafted magnetic nanocomposite particles (Mag-Im18). The amount of polymer anchored on the particle was estimated by elemental analysis to be 5 wt %. The surface coverage of imidazolyl groups was estimated to be 0.44 mmol g-1. A stable Mag-Im18 suspension was prepared, and the polymer coatings were chemically stable over a pH range of 3.5−10.0. The Mag-Im18 showed a selective binding of divalent metal ions with a binding strength in the order of Cu2+ ≫ Ni2+ > Co2+. At pH 5.3, the limiting adsorption capacity for Cu2+ ion was 0.11 mmol g-1. Selective separation/recovery of Cu2+ ions from a Cu2+/Co2+ aqueous solution was demonstrated over a pH range of 3−7.

A new strategy is described for generating strong circularly polarized luminescence with highly tunable emission bands through chiral induction in nonchiral, totally organic, low-molecular-weight fluorescent dyes by chiral nanotemplate systems. Our approach allows the first systematic investigation to clarify the correlation between the circular dichroism and circularly polarized luminescence intensities. As a result, a dilute solution system with the highest circularly polarized luminescence intensity achieved to date and a dissymmetry factor of over 0.1 was identified.

A new organogelator based on a salicylideneaniline derivative with cholesterol moieties was synthesized, and it was proposed that it could gelate various organic solvents, such as 1-butanol, 1-octanol, butyl acetate, tetrachloromethane, benzene, toluene through combination with a gelation test. From the results of analysis by UV/Vis absorption, circular dichroism (CD), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies and semiempirical (AM1) calculations, we believed that the gelator molecules could self-assemble into left-handed helical nanofibers through unimolecular layer packing, which further twisted into the thicker fibers and constructed 3D networks in the gel phase. Interestingly, the organogel exhibited strong fluorescence enhancement relative to a solution of the same concentration because of the formation of J aggregations. Meanwhile, photochromism of the organogel could take place under UV-light irradiation. Both strong fluorescence emission and photochromism properties were concurrent in one system based on a salicylideneaniline derivative. It was suggested that the self-assembly of the functional organogelator could lead to unique photophysical properties.

A series of helically folded oligoamides of 8-amino-2-quinoline carboxylic acid possessing 6, 7, 8, 9, 10 or 16 units are prepared following convergent synthetic schemes. The right-handed (P) and the left-handed (M) helical conformers of these oligomers undergo an exchange slow enough to allow their chromatographic separation on a chiral stationary phase. Thus, the M conformer is isolated for each of these oligomers and its slow racemization in hexane/CHCl(3) solutions is monitored at various temperatures using chiral HPLC. The kinetics of racemization at different temperatures in hexane/CHCl(3) (75:25 vol/vol) are fitted to a first order kinetic model to yield the kinetic constant and the Gibbs energy of activation for oligomers having 6, 7, 8, 9, 10 or 16 quinoline units. This energy gives the first quantitative measure of the exceptional stability of the helical conformers of an aromatic amide foldamer with respect to its partly unfolded conformations that occur between an M helix and a P helix. The trend of the Gibbs energy as a function of oligomer length suggests that helix-handedness inversion does not require a complete unfolding of a helical strand and may instead occur through the propagation of a local unfolding separating two segments of opposite handedness.

Double-chain alkyl amphiphiles with oligo-l-glutamic acid-head group were prepared. These compounds were dispersed in water at pH 8 to 9 to form bilayer aggregates, in which helical and hollow structures were contained. New CD bands were observed in the solution.

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A new helical aromatic oligoamide foldamer, bearing triethyleneglycol side chains for solubility in a broad range of media, was prepared. The stability of the helical conformation was assessed in various solvents and shown to vary greatly and unexpectedly. Stability was remarkably enhanced in methanol-water mixtures.

Microfibrous self-aggregation of chromophoric groups of porphyrin and/or pyrene substituted by didodecyl L-glutamic acid in organic media is confirmed by transmission electron microscopic (TEM) observation. Chromophoric probes of porphyrin and pyrene moieties enable evaluation of their assembling behavior photophysically through UV-vis, circular dichroism (CD), and fluorescence spectroscopic characterization. This spectroscopic characterization was able to compensate the lack of TEM observation for the aggregation even at a low concentration below the critical gel concentration. The temperature affects the salient features of the photophysics of porphyrin or pyrene in the microfibrous assemblies. Highly oriented network structures were formed at low temperature since the CD intensities of the porphyrin and pyrene systems increased with lowering the temperature. Fluorescence spectroscopic characterization confirmed the monomer excitation of porphyrin itself, and efficient excimer formation for the pyrene-pyrene charge transfer was detected at low temperature. In particular, we also obtained the preliminary results of fluorescence spectroscopic measurement on singlet-singlet energy migration from pyrene to porphyrin in the mixed assemblies for mimicry of the efficient energy transfer process of the photosynthetic antenna complex.