Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

Fluorometric and colorimetric sensor for selective detection of cyanide anion by dibenzosuberenone-based dihydropyridazine in aqueous solution

A new chemosensory based on deprotonation and intramolecular charge transfer (ICT) was developed to detect cyanide in food samples. Deprotonation was facilitated by increasing the acidity of the NH proton in the dibenzosuberenone-based dihydropyridazine chemosensor Pz3 with -CN substituents. Addition of cyanide to acetonitrile and aqueous acetonitrile solution (1/9) of Pz3 resulted in their significant color change from colorless to purple in visible light, accompanied by a strong red shift in the absorption spectrum. Meanwhile, the near-infrared (NIR) emission (ex. 525 nm, em. 670 nm) of Pz3- resulting from deprotonation showed fluorescence switching behavior to detect the cyanide anion. While the acidic NH protons interact with basic anions as F-, CN-, OAc- and H2PO4- in organic solution (MeCN), just CN ions interact with in aqueous organic solutions (H2O-MeCN 1/9 HEPES pH 7.4). The limit of detection of cyanide from the fluorescence spectrum is 80 nM, which is well below the value determined for drinking water by World Health Organization (WHO). The interference effect of cations and anions showed that Pz3 could play an important role in the determination of waste NaCN. In addition, Pz3 successfully carried out the selective detection of cyanide in food samples such as bitter almonds and sprouting potatoes.

Synthesis and Properties of Azahomocorannulenyl Cations and Radicals

Cycloheptatrienyl (tropyl) molecules are representative non-alternant hydrocarbons that offer interesting chemistry because of their unique structures and properties. However, there have been a limited number of polycyclic aromatic tropyl cations and radicals reported in the literature. Herein, we report the synthesis of a series of azahomocorannulene derivatives, where the key reactions are a 1,3-dipolar cycloaddition of polycyclic aromatic azomethine ylides with dibenzotropone and a subsequent palladium-catalyzed cyclization. X-ray diffraction analysis revealed that the obtained azahomocorannulenyl cation and radical adopt planar structures and exhibit unique packing structures. Their electronic and optical properties were investigated experimentally and theoretically to reveal their aromatic character.

One-Pot Synthesis of Polycyclic 4,5-Dihydropyridazine-3(2H)-ones by Inverse Electron-Demand Diels-Alder (IEDDA) Reactions from Alkenes

In the classical Inverse Electron-Demand Diels-Alder (IEDDA) reactions between alkenes and tetrazines, 4,5-dihydropyridazines are formed. 4,5-Dihydropyridazines are rapidly converted to the more energetically stable 1,4-dihydropyridazines by 1,3-prototropic isomerization. In this study, instead of 1,4-dihydropyridazines, 4,5-dihydropyridazine-3(2H)-ones were obtained as a result of IEDDA reactions between tetrazines with leaving groups at the 3,6-positions, and norbornene and barrelene-derived polycyclic alkenes in the presence of moisture in air or solvent. To show that this new method works not only on strained polycyclic alkenes but also on monocyclic and linear alkenes, the corresponding 4,5-dihydropyridazine-3(2H)-ones were obtained in high yields from the reactions performed with styrene and cyclopentene as well. The chemical structures of the polycyclic 4,5-dihydropyridazine-3(2H)-ones were determined by NMR and HRMS analyses. In addition, the exact structures of the polycyclic 4,5-dihydropyridazine-3(2H)-ones were also experimentally proven by converting them to pyridazine-3(2H)-ones known in the literature.

A New Reversible Colorimetric Chemosensor Based on Julolidine Moiety for Detecting F. J Fluoresc 2021;31:1675-1682. [PMID: 34387807 DOI: 10.1007/s10895-021-02801-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

We synthesized an original reversible colorimetric chemosensor PDJ ((E)-9-((2-(6-chloropyridazin-3-yl)hydrazono)methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol) for the detection of F^-. PDJ displayed a selective colorimetric detection to F^- with a variation of color from colorless to yellow. Limit of detection of PDJ for F^- was calculated as 12.1 µM. The binding mode of PDJ and F^- turned out to be a 1:1 ratio using Job plot. Sensing process of F^- by PDJ was demonstrated by ¹H NMR titration and DFT calculation studies that suggested hydrogen bond interactions followed by deprotonation. Moreover, the practicality of PDJ was demonstrated via a reversible test with TFA (trifluoroacetic acid).

Dibenzosuberenone-Based Photo- and Thermochromic Switches, a Transformation: Rearrangement of Dibenzosuberenones to Spiro Anthrones

In this study, a new class of photo- and thermochromic compounds was discovered. Fluorescent dihydropyridazine-appended dibenzosuberenone derivatives with central seven-membered rings were converted to colorless spiro anthrones with central six-membered rings by thermal isomerization or visible-light (420 nm) irradiation. Under UV light (350 nm), the spiro anthrones converted back to benzosuberenones. The chemical structures of the spiro anthrones were determined by NMR, UV-vis spectroscopy, and HRMS analyses. It was also observed that the dibenzosuberenone derivatives were oxidized on exposure to UV irradiation for a long time.