Ag(I)大環状化合物による非ウェルナー型配位結合を用いた多点分子認識

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 塩谷 光彦, 東京大学教授 西原 寛, 東京大学教授 佃 達哉, 東京大学准教授 ILIES LAUREAN, 東京大学准教授 山野井 慶徳University of Tokyo(東京大学

Effects of Substituents on the Blue Luminescence of Disilane-Linked Donor‒Acceptor‒Donor Triads

A series of disilane-linked donor‒acceptor‒donor triads (D‒Si‒Si‒A‒Si‒Si‒D) was synthesized to investigate the effects of substituents on the photophysical properties. The triads were prepared by metal-catalyzed diiodosilylation of aryl iodides using a Pd(P(t-Bu)3)2/(i-Pr)2EtN/toluene system that we previously developed. Optical measurements, X-ray diffraction analysis, and density functional theory calculations revealed relationships between the photophysical properties and molecular structures of these triads in solution and in the solid state. The compounds emitted blue to green fluorescence in CH2Cl2 solution and in the solid state. Notably, compound 2 showed fluorescence with an absolute quantum yield of 0.17 in the solid state but showed no fluorescence in CH2Cl2. Our findings confirmed that the substituent adjacent to the disilane moiety affects the conformations and emission efficiencies of compounds in solution and in the solid state

Regulation of Lithospermic Acid B and Shikonin Production in Lithospermum erythrorhizon Cell Suspension Cultures

Cell suspension cultures of Lithospermum erythrorhizon produced a large amount of lithospermic acid B, a caffeic acid tetramer, as well as shikonin derivatives (each ca. 10% of dry wt.) when cultured in shikonin production medium M-9. Various culture factors for increasing the production of lithospermic acid B were investigated. Lithospermic acid B production was inhibited by 2, 4-D or NH4+, whereas it was stimulated by Cu2+. These regulatory patterns were similar to those for the production of shikonin derivatives in these cell cultures, suggestive of close relations and similar metabolic regulation between the production of these compounds. Cultivation under light illumination, however, showed that these metabolisms were independently regulated. In particular, blue light showed a stimulatory effect on lithospermic acid B production, while shikonin production was strongly inhibited, indicative of an effective condition for lithospermic acid B production

Airway obstruction caused by achalasia: A case report

We report a rare case of airway obstruction caused by megaesophagus associated with achalasia. A 78-year-old man was admitted with post meal dyspnea, decreased consciousness, expiratory and inspiratory wheezing, and respiratory distress. Arterial blood gas analysis showed findings of marked acute respiratory acidosis (pH 7.18, PaCO2 75 mmHg, PaO2 225 mm Hg, HCO3− 22 mmol/L). An emergency laryngoscopy was performed because of a suspected airway obstruction, but no abnormalities were observed from the airway to the glottis. Noninvasive positive pressure ventilation (NPPV) was immediately introduced, and the respiratory rate and breathing pattern was normalized. A chest X-ray showed an enlarged upper mediastinal outline and an ill-defined border of the trachea. A computed tomography (CT) scan showed an enlarged esophagus with a maximum diameter of 9.90 cm, compressing the trachea to the back of the sternal notch. Following removal of the esophageal contents using a nasogastric tube, NPPV was discontinued with no respiratory episodes. After he was stabilized, he was transferred to another hospital for endoscopic myotomy. In a review of the literature, we identified 66 cases of airway obstruction due to achalasia, mainly in older women. None of the patients received NPPV. As a differential diagnosis for acute airway obstruction, achalasia-related airway obstruction should be considered, particularly in older women. Furthermore, since this condition is suspected to involve tracheomalacia, NPPV may be a useful respiratory support therapy

Extended Tripodal Hydrotris(indazol‐1‐yl)borate Ligands as Ruthenium‐Supported Cogwheels for On‐Surface Gearing Motions

International audienceThis paper reports the synthesis of ruthenium‐based molecular gear prototypes composed of a brominated or non‐brominated pentaphenylcyclopentadienyl ligand as an anchoring unit and a tripodal ligand with aryl‐functionalized indazoles as a rotating cogwheel. Single crystal structures of the ruthenium complexes revealed that the appended aryl groups increase the apparent diameter of the cogwheel rendering them larger than the diameter of the anchoring units and consequently making them suitable for intermolecular gearing motions once the complexes will be adsorbed on a surface

Extension of Pt–Ag cluster units by incorporating silver salts

A sterically controlled Z-shaped Pt2Ag2 complex showed a metalation reaction with a Ag ion via the formation of the thermodynamically unfavorable Pt2Ag2 complex with U-shaped configuration. Multiple dative bond formation between Pt and an additional Ag ion endowed enough thermodynamic stability on the Pt2Ag3 cluster to overcome the unfavorable steric effect from bulky substituents on the ligands in the U-shaped structure. A single crystal X-ray structural analysis revealed dimerized structure of the cationic Pt2Ag3 complex units bridged by [Ag2(OTf)4] 2− (OTf− = triflate anion) via strong Ag–π coordination with pyrazole moiety in the solid state. The heteropolynuclear complexes showed photoluminescence properties depending on the structure of the Pt–Ag clusters.Chemistry Letters, 53(1), art. no. upad004; 202

Multipoint Recognition of Ditopic Aromatic Guest Molecules via Ag−π Interactions within a Dimetal Macrocycle

A macrocyclic host molecule possessing a nanocavity with two Ag^I centers for guest binding and four anthracene walls has been developed. This dimetal-macrocycle forms stable inclusion complexes with ditopic aromatic guest molecules, [2.2]­paracyclophane, and ferrocene, in solution and/or in the solid state through Ag−π interactions within the nanocavity. The binding constants for the inclusion complexes were found to range roughly from 10⁴ to 10⁹ M^–1. Electrochemical measurement revealed that the oxidized form of the included cationic ferrocene was less stabilized due to the direct binding to the cationic two Ag^I centers

Procrystalline Self-Assembly of Desymmetrized Pentaphenylcyclopentadiene

International audienceThe interplay between the molecular shape and the intermolecular interaction plays a decisive role in self-assembled structures. Recently, inherent randomness of low ordered assemblies, resulting from lack of short- and long-range periodicities, has attracted significant attention due to the unique structural, electronic, and mechanical properties. Here, we present procrystalline self-assemblies of pentaphenyl cyclopentadienyl derivatives on Ag(111) and Au(111) with scanning tunneling microscopy, operating at 4.3 K under ultrahigh vacuum conditions. Two examples, using 5-fold symmetric molecules substituted with methyl or fluorine groups, show that weak interactions, such as π–π stacking, CH−π interactions, and CH···F hydrogen bonding, play a pivotal role in formation of the procrystalline assembly. Our results may give insights into the intricate relationship between the molecular shape and the intermolecular interaction in the formation of non-crystalline assemblies