Toshihiko Sakurai

Stabilization of enhanced chirality from pyrene-containing L-glutamide lipid in methyl methacrylate by photo-induced polymerization

Enhanced CD spectra based on chirally-oriented structures of pyrene-containing L-glutamic acid-derived lipid were observed in polymerizable monomers and CD strength was maintained after photo-induced polymerization of the monomer solvents.

Reversible gelation in cyclohexane of pyrene substituted by dialkyl L-glutamide: photophysics of the self-assembled fibrillar network

Abstract l- Glutamic acid-derived compound with pyrenyl group was able to form organic gels in benzene, cyclohexane, and so on. The gels were produced through the formation of highly oriented aggregates and a remarkable development of their fibrous polymer networks. Our scopes of this study are to present the salient features of the photophysics of pyrene in the highly oriented fibrillar network in cyclohexane and to describe spectroscopic measurements used either to detect pyrene association prior to excitation or to confirm the absence of aggregated pyrenes. The concentration and the temperature affected the gel-formation. The sol in the concentration below critical gel concentration includes nanoassemblies with highly oriented aggregates of the compound. Functionalization of l -glutamide derivative with different head groups using electron accepting pyrene and electron-donating N,N-dimethylaniline (DMA) chromophores was also performed to detect the exciplex formation as the mimicry of the photoinduced electron transfer process in the photosynthesis. Upon cooling from 60 to 10 °C, red shifted fluorescence from 446 to 456 nm ascribed to the charge transfer from DMA to pyrene was observed in the mixed system of pyrene- and DMA-containing l -glutamide derivatives in cyclohexane.

Poly(4‐Vinylpyridine) as Novel Organic Phase for RP‐HPLC. Unique Selectivity for Polycyclic Aromatic Hydrocarbons

Abstract Subsidiary weak interaction such as π–π interaction shows us unique separation even in RP‐HPLC. This communication shows the first example that poly(4‐vinylpyridine) on silica provides extremely large selectivity with specificity for polycyclic aromatic hydrocarbons in methanol–water as a mobile phase. It also describes that the selectivity mode does not always obey those in conventional π‐electron‐containing stationary phases.

Novel self-assembling organogelators by combination of a double chain-alkylated L-glutamide and a polymeric head group

This communication introduces a new class of self-assembling organogelators composed of a double chain-alkylated L-glutamide with a polymeric head group.

Controllable shape selectivity based on highly ordered carbonyl and methyl groups in simple β-structural polypeptide on silica

Poly(l-alanine)-grafted porous silica (Sil-Ala(22)) was prepared by polymerization of N-carboxyanhydride of l-alanine initiated by 3-aminopropylated silica. The retention behaviors of the column packed with Sil-Ala(22) were investigated by using alkylbenzenes and polycyclic aromatic hydrocarbons as injection samples in liquid chromatography. The Ala(22) phase was in a rigid beta-form structure and thus provided specific interaction sites, which were derived from the highly ordered carbonyl and methyl groups. These interaction sites bring unique molecular-shape discriminations: molecular-length and non-planarity selectivity, which are controllable by altering organic solvent used as a part of mobile phase.

Synthesis of functional poly(amino acids) on cyclophosphazene templates

With the use of hexakis(p-aminophenoxy)cyclotriphosphazene and tetraphenyltetraaminocyclotetraphosphazene whose primary groups initiated the polymerization of L-α-alanine and γ-esters of L-α-glutamic acid n-carboxyanhydrides, poly(amino acids) containing an inorganic central ring have been prepared. Polypeptide chains of various lengths have been obtained by variation of the monomer-to-initiator molar ratio. The molecular masses of the synthesized samples are in good agreement with the calculated parameters, and the polymers show a narrow molecular-mass distribution (M w /M n < 1.3). The circular dichroism (CD) spectra and IR studies indicate a predominantly helical conformation of poly(amino acid) chains with the central triphosphazene ring and the disordered structure of poly(amino acid) chains bonded to cyclotetraphosphazene.

Facile Enantiomer Analysis by Combination of N‐Dansyl Amino Acid as Diastereomerizer and Molecular‐Shape Recognitive RP‐HPLC Using Comb‐Shaped Polymer‐Immobilized Silica

Abstract Poly(octadecyl acrylate)‐grafted silica has been developed as a special stationary phase showing molecular‐shape recognition in high‐performance liquid chromatography. The bonded polymer phase is characterized by the fact that the polymer forms highly‐ordered structures similar to a solvated crystalline state on silica and multiple π–π interaction between carbonyl groups in the polymer and aromatic solutes is promoted. This paper shows that the selectivity for DL‐amino acids diastereomerized with N‐dansyl L‐proline can be enhanced by using the polymer stationary phase instead of octadecylated silica (ODS).

Dendritic Cyclotriphosphazene Derivative with Hexaxis(alkylazobenzene) Substitution as Photo-sensitive Trigger

A dendritic cyclotriphosphazene derivative was synthesized by substitution with six alkylazobenzenes onto cyclotriphosphazene. Photo-induced trans-to-cis isomerization of the azobenzene moieties was discussed on each substituent. It was also investigated that the dendrimer acted as a photosensitive trigger for microenvironmental modification of chirally self-assembled organogels through the isomerization.

The Impact of Self-Assembly in Medicine and Pharmacology

The concept, molecular self-assembly, especially considering molecule-molecule interaction as an information- processing phenomenon, have a profoundly novel effect on thoughts and efforts related to Medicine and Pharmacology. This new style of thinking is still too novice to be used solely and independently for explanation of disease mechanisms and appropriate treatment strategies. However it calls for a range of new researches based on new predictions about disease mechanisms (especially Autoimmune diseases, Endocrinopathies, and Neoplasms) and relevant treatment strategies (superstructural drugs).