Norcaradiene intermediates in mass spectral fragmentations of tropone and tropothioneElectronic supplementary information (ESI) available: reaction paths supporting Figs. 3â€“6. See http://www.rsc.org/suppdata/p2/b1/b102127n/

Ishiwata, Akihiro; Yamabe, Shinichi; Minato, Taketoshi; Machiguchi, Takahisa

doi:10.1039/b102127n

Cited by 4 publications

(2 citation statements)

References 25 publications

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“…A suggestion for how the ligand has undergone fragmentation involves the decomposition of the phenyl moiety. This has been seen in the literature where tropone first loses CO to yield a phenyl cation radical, which then leads to the decomposition of the phenyl moiety [61]. Table 4.…”

Section: Mass Spectrometrymentioning

confidence: 69%

Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine

et al. 2022

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Copper(II) complexes of glycyl-L-leucyl-L-histidine (GLH), sarcosyl-L-leucyl-L-histidine (Sar-LH), glycyl-L-phenylalanyl-L-histidine (GFH) and sarcosyl-L-phenylalanyl-L-histidine (Sar-FH) have potential anti-inflammatory activity, which can help to alleviate the symptoms associated with rheumatoid arthritis (RA). From pH 2–11, the MLH, ML, MLH-1 and MLH-2 species formed. The combination of species for each ligand was different, except at the physiological pH, where CuLH-2 predominated for all ligands. The prevalence of this species was supported by EPR, ultraviolet-visible spectrophotometry, and mass spectrometry, which suggested a square planar CuN4 coordination. All ligands have the same basicity for the amine and imidazole-N, but the methyl group of sarcosine decreased the stability of MLH and MLH-2 by 0.1–0.34 and 0.46–0.48 log units, respectively. Phenylalanine increased the stability of MLH and MLH-2 by 0.05–0.29 and 1.19–1.21 log units, respectively. For all ligands, 1H NMR identified two coordination modes for MLH, where copper(II) coordinates via the amine-N and neighboring carbonyl-O, as well as via the imidazole-N and carboxyl-O. EPR spectroscopy identified the MLH, ML and MLH-2 species for Cu-Sar-LH and suggested a CuN2O2 chromophore for ML. DFT calculations with water as a solvent confirmed the proposed coordination modes of each species at the B3LYP level combined with 6-31++G**.

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Section: Mass Spectrometrymentioning

confidence: 69%

Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine

et al. 2022

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“…We strategically used a long-chain ketone (nonadecan-10-one) to ensure the solubility of the resulting compounds and their polymers, but we found the same efficiency with short-chain ketones as well (e.g., pentan-3-one, data not shown). This one-step method is quite simple and high yielding when compared to other methods (such as selenium dioxide oxidation of cycloheptatriene and Hofmann degradation of tropinone) and enables the synthesis of many derivatives of different side chains. Next, in order for cross-coupling polymerization, we attempted halogenation at the thiophene moiety of 2 , but bromination either with N -bromosuccinimide or bromine was unsuccessful, probably due to the electron-poor character of tropone-fused thiophene 2 .…”

Section: Results and Discussionmentioning

confidence: 99%

Torsionally Responsive Tropone-Fused Conjugated Polymers

et al. 2015

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Torsionally responsive molecular systems can change their electronic properties according to the dihedral angles and can be utilized as sensory materials. We have designed and synthesized novel tropone-fused conjugated polymers PBTr, PBTr-T, and PBTr-Tz that showed interesting dihedral-angledependent variations in UV−vis absorptions. Tropone-fused thiophene derivatives were prepared from one-step condensation of thiophene-3,4-dialdehyde and aliphatic ketones via a modular, facile, and high-yielding method. Subsequent halogenation and Stille cross-coupling polymerization with a bis(stannyl)benzodithiophene resulted in a tropone-fused conjugated polymer PBTr. We were also able to prepare thiophene-and thiazolebridged polymers, PBTr-T and PBTr-Tz, respectively, using similar synthetic methods. Electronic absorptions of the newly synthesized PBTrs were measured in solutions and in films states. Substantial red-shifts occurred in the case of thiophene-bridged PBTr-T, whereas almost no shift was observed for thiazolebridged PBTr-Tz. We attributed this to the substantial change in the torsional angle between the tropone-fused thiophene moiety and thiophene, which was further supported by density functional theory (DFT) calculations. Similar spectral changes of UV−vis absorptions were observed when a poor solvent (methanol) was introduced to a chloroform solution of PBTr-T. Reverse torsional angle variations were realized with initially planar PBTr-Tz by introducing steric hindrance through protonation on the thiazole rings. We believe that torsionally responsive tropone-fused conjugated polymers are promising as novel platforms for sensory applications.

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