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Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis.

ABSTRACT: Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (-COCN₂-) attached to position 5' or 6' of the pendant phenyl rings. For that, the mixture of 5'- or 6'-bromo derivatives of the parent dye was prepared, transformed into 1,2-diarylacetylenes, hydrated to 1,2-diarylethanones, and converted to diazoketones Ar¹COCN₂Ar². The high performance liquid chromatography (HPLC) separation gave four individual regioisomers of Ar¹COCN₂Ar². Photolysis of the model compound─C₆H₅COCN₂C₆H₅─in aqueous acetonitrile at pH 7.3 and under irradiation with 365 nm light provided diphenylacetic acid amide (Wolff rearrangement). However, under the same conditions, Ar¹COCN₂Ar² gave mainly α-diketones Ar¹COCOAr². The migration ability of the very bulky dye residues was low, and the Wolff rearrangement did not occur. We observed only moderate fluorescence increase, which may be explained by the insufficient quenching ability of diazoketone bridge (-COCN₂-) and its transformation into another (weaker) quencher, 1,2-diarylethane-1,2-dione.

SUBMITTER: Shojaei H

PROVIDER: S-EPMC8749961 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature

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Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis.

Shojaei Heydar H Bossi Mariano L ML Belov Vladimir N VN Hell Stefan W SW

The Journal of organic chemistry 20211217 1

Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (-COCN<sub>2</sub>-) attached to position 5' or 6' of the pendant phenyl rings. For that, the mixture of 5'- or 6'-bromo derivatives of the parent dye was prepared, transformed into 1,2-diarylacetylenes, hydrated to 1,2-diarylethanones, and converted to diazoketones Ar<sup>1</su ...[more]

PMID: 34919387

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Project description:Binuclear and multinuclear complexes have attracted much attention due to their unique catalytic performances for olefin polymerization compared with their mononuclear counterparts. In this work, a series of phenyl-bridged bis-β-carbonylenamine [O-NSR] (R = alkyl or phenyl) tridentate ligands and their binuclear titanium complexes (Ti2L1-Ti2L5) were synthesized and characterized by 1H NMR, 13C NMR, FTIR and elemental analysis. The molecular structure of ligand L2 (R = n Pr) and its corresponding Ti complex Ti2L2 were further investigated by single-crystal X-ray diffraction, which showed that each titanium coordinated with six atoms to form a distorted octahedral configuration along with the conversion of the ligand from β-carbonylenamine to β-imino enol form. Under the activation of MMAO, these complexes catalyzed ethylene polymerization and ethylene/α-olefin copolymerization with extremely high activity (over 106 g mol (Ti)-1 h-1 atm-1) to produce high molecular weight polyethylene. At the same time, wider polydispersity as compared with the mononuclear counterpart TiL6 was observed, indicating that two active catalytic centers may be present, consistent with the asymmetrical crystal structure of the binuclear titanium complex. Furthermore, these complexes possessed better thermal stability than their mononuclear analogues. Compared with the complexes bearing alkylthio sidearms, the complex Ti2L5 bearing a phenylthio sidearm exhibited higher catalytic activity towards ethylene polymerization and produced polyethylene with much higher molecular weight, but with an appreciably lower 1-hexene incorporation ratio. Nevertheless, these bis-β-carbonylenamine-derived binuclear titanium complexes showed much higher ethylene/1-hexene copolymerization activity and 1-hexene incorporation ratios as compared with the methylene-bridged bis-salicylaldiminato binuclear titanium complexes, and the molecular weight and 1-hexene incorporation ratio could be flexibly tuned by the initial feed of α-olefin commoners and catalyst structures.

Dataset Information

Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis.

Publications

Bis-Rhodamines Bridged with a Diazoketone Linker: Synthesis, Structure, and Photolysis.

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