掲載種別：研究論文（学術雑誌）  

Non-covalent interactions offer an alternative way for developing stimulus-responsive materials such as sensors, machines, and drug-delivery systems. We recently reported that a urethane-equipped tetrakis(porphyrin) forms one-handed helical supramolecular polymers in solution in response to chirality of chiral solvents. Conformational changes in helical sense were detected using circular dichroism (CD) spectroscopy, which showed that the tetrakis(porphyrin) can possibly be used as a sensor for determining the enantiomeric excess of a chiral analyte. Hence, we studied the scope and limitations of the chiral-induction behavior of tetrakis(porphyrin) to deepen the understanding of tetrakis(porphyrin)-based chiral sensing systems. Herein, we report the chiral-induction behavior of tetrakis(porphyrin) in various chiral solvents, which was found to be CD-active in many chiral solvents. Notably, the tetrakis(porphyrin) was CD active in a cryptochiral molecular solvent, which is exciting because the chiralities of acyclic saturated hydrocarbons are hard to sense. Consequently, this study highlights the potential advantages of supramolecular chiral sensors capable of targeting a wide range of analytes, including molecules that are absorption-silent in the UV/vis region, ones devoid of anchoring functional groups, and acyclic, saturated hydrocarbons.

DOI： 10.1002/chem.202403569

Open Access

Scopus

PubMed

掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

Abstract

Tetrakisporphyrin monomers with amino acid side chains at each end form intramolecular antiparallel hydrogen‐bonds to adopt chirally twisted pseudo‐macrocyclic structures that result in right‐handed and left‐handed (P)‐ and (M)‐conformations. The pseudo‐macrocyclic tetrakisporphyrin monomers self‐assembled to form supramolecular helical pseudo‐polycatenane polymers via head‐to‐head complementary dimerization of the bisporphyrin cleft units in an isodesmic manner. The formation of one‐handed supramolecular helical pseudo‐polycatenane polymers was confirmed by circular dichroism (CD) spectroscopy. The methyl and iso‐propyl groups at the stereogenic center greatly enhanced the induced circular dichroism in the Soret bands of the supramolecular helical pseudo‐polycatenane polymers. The induced CDs were reduced upon the introduction of large iso‐butyl and tert‐butyl groups. Atomic force microscopy revealed well‐grown and long supramolecular helical pseudo‐polycatenane polymer chains with chain lengths in the range of 361 to 13.6 nm. The right‐handed helical chains were established by the self‐assembly of the right‐handed (P)‐conformation of the pseudo‐macrocyclic monomer.

DOI： 10.1002/anie.202416770

Open Access

Scopus

掲載種別：研究論文（学術雑誌）  

In this report, we describe the self-assembly behavior of neutral platinum complexes in toluene. The platinum complexes were seen to form two different types of assemblies depending on the preparation temperature.

DOI： 10.1039/d2cc02571j

Scopus

PubMed

掲載種別：研究論文（学術雑誌）  

Neutral platinum complexes that possess chiral triethylene glycol (TEG) moieties were synthesized. The platinum complexes formed helically twisted stacked assemblies in chloroform and toluene, which were studied by1H NMR, UV/vis spectroscopy, and emission spectroscopy. On the other hand, emissive micellar aggregates were observed in a THF/water mixed solvent. Dynamic light scattering (DLS) experiments revealed that micellar aggregates with a diameter (d) of ≈100 nm emitted strong light, whereas the monomeric form and large aggregates (d> 500 nm) did not show luminescence efficiently. Furthermore, the micellar aggregates were twisted chirally, where the twisted direction was determined by the chirality of the TEG moieties. The assemblies were observed to be solvent responsive, which allows for the modulation of the nanostructure by changing the solvent polarity.

DOI： 10.1039/d1ob00492a

Scopus

PubMed