Two Different Clar's Sextets: Clar's Rule Does Not Necessarily Contradict the Global Pathway of Conjugated Macrocycles.

Two contradictory theories, Clar's sextet and resonance theory, explain the stability of conjugated macrocycles using localized and delocalized models, respectively. To reconcile these theories and gain better insights, PAH-containing porphyrinoids were chosen as a representative class of conjugated macrocycles. Two types of Clar's sextets were identified and proposed for the first time based on their interaction with global conjugated pathways: (i) shared sextets that integrate with and perturb the global resonance pathway, and (ii) independent sextets that are separate from the pathway and potentially stabilize or do not perturb it.

Effects of Electron-Withdrawing and Electron-Donating Groups on Aromaticity in Cyclic Conjugated Polyenes.

Determining the aromaticity of various fluorinated benzenes is challenging as easily obtained experimental aromaticity [Δδ( - )] necessitates the chemical shifts of inner and outer protons. This issue was addressed in porphyrinoids by replacing the electron-withdrawing (E.W.

Neuroprotective Effects of Roots and Its Active Constituents on Scopolamine-Induced Memory Impairment in In Vivo and In Vitro Studies.

Beta-amyloid (Aβ) proteins, major contributors to Alzheimer's disease (AD), are overproduced and accumulate as oligomers and fibrils. These protein accumulations lead to significant changes in neuronal structure and function, ultimately resulting in the neuronal cell death observed in AD. Consequently, substances that can inhibit Aβ production and/or accumulation are of great interest for AD prevention and treatment.

Anti-Amyloidogenic Effects of Fruits and Its Active Constituents.

Alzheimer's disease (AD) is a serious neurodegenerative brain disease that interferes with daily life. The accumulation of beta-amyloid (Aβ), along with oxidative stress-inducing neurocellular apoptosis, has been considered one of the causes of AD. Thus, the purpose of this study is to find natural products that can reduce Aβ accumulation.

Synthesis of Dioxa-1,7-naphthicorrole and Its Oxidized Porphyrinoid as a Potential Built-In Linker for Biomolecules.

The first aromatic benzicorrole termed naphthicorrole was synthesized with a carbon donor containing more than six members. Its oxidized (enedione-embedded) porphyrinoid was also obtained using different meso-aryl substitutions under sequential oxidation conditions. The resulting enedione motif of the nonaromatic porphyrinoid was regioselective to the C2 position for S or N nucleophiles.

-(2-Thienyl)vinylarene as an Alternative Synthetic Motif for Porphyrinoids: -Arene-Connected Porphyrinoids.

-Arene-connected porphyrinoids were synthesized with -(2-thienyl)vinylarene motif as a new building block for porphyrinoids. This motif can replace meso-aryl-substituted dipyrromethene and serve as a command key arranging -connectivity of porphyrinoid. While (benzene version) is very weak, (pyridine version) shows a substantial amount of diatropic ring current due to reduced steric hindrance (without H23) and rigidified became more aromatic than .

Carbaporphyrin Dimers That Bear a Rigid Naphthalene Motif as an Internal Strap.

The first fully connected aromatic carbaporphyrin dimer () and its bis-Pd complex () that bear a rigid naphthalene motif as an internal strap were synthesized. These dimers consisted of two aromatic carbaporphyrins that shared a naphthalene motif. The π-electron conjugation of the obtained macrocycles was proposed to have two separated local 22 π-electron pathways and a 34 π-electron pathway.

Tuned Cd Selectivity: Showcase of Electronic and Regio-Effect of π-Extended Di-2-Picolylamine-Substituted Quinoline-Based Tolans.

π-Extended di-2-picolylamine (DPA)-substituted 8-hydroxyquinoline (8-HQ) tolans () were synthesized for testing electronic and regio-effects. The electron-poor CN-tolan () showed clear selectivity for Cd (>>Zn) over other metal ions via turn-on fluorescence, while the electron-rich MeO-tolan () displayed no clear metal selectivity. Furthermore, considering that there was no significant energy difference between the Cd complexes of and , the intended regio-effect (7- vs.

Systematic Modifications of a Simple Tolan: Another Category of Viscosity Sensor.

The first tolan derivative-based viscosity sensor () has been synthesized, and its fluorescence intensity and lifetime increase when the viscosity of the solvent increases in methanol-glycerol mixtures. Phthalide () was selected among structurally diverse tolan derivatives through systematic modifications of a simple tolan. To test as a viscosity sensor, fluorescence lifetime imaging (FLIM) images of HeLa cells were obtained upon treatment with 5 μM of to map the viscosity of the HeLa cells.

Bond Rotation in an Aromatic Carbaporphyrin: Allyliporphyrin.

Allyliporphyrin is a carbaporphyrin that has replaced one pyrrole with an allyl group. Dynamic behavior (bond rotation) was observed by variable temperature H NMR and 2D-NOESY NMR spectroscopy and theoretically examined by DFT calculations. These studies revealed that well-defined bond rotation was first observed in the limited space of the carbaporphyrin from 2 through cis-2 and the calculated rotational barrier was low enough, with the relative energy level of cis-2 only 0.

Fluorescent and cooperative ion pair receptor based on tolan for Na (or Li) and HSO: logic AND gate.

A tolan derivative was synthesized as a fluorescent and cooperative ion pair receptor. As both Na and HSO ions were complexed to the receptor, only substantial fluorescence was quenched. Thus, it also acts as a logic AND gate.