23302-83-2Relevant articles and documents
Complexes of carboxylato pillar[6]arene with Brooker-type merocyanines: Spectral properties, pKa shifts and the design of a displacement assay for trimethyl lysine
Hessz, Dóra,Bádogos, Stella,Bojtár, Márton,Bitter, István,Drahos, László,Kubinyi, Miklós
, (2021/02/02)
The supramolecular complexes of three strongly solvatochromic dyes, Brooker's merocyanine (M1) and its two derivatives (M2, M3) with carboxylato pillar[6]arene (WP6) were studied in aqueous solutions. The dye-WP6 mixtures were described in terms of four equilibrium reactions: the acidic dissociations of the pyridinium phenols into the zwitterionic phenolates, the acidic dissociations of the complexed phenols, the bindings of the phenol form dyes to WP6 and the bindings of the phenolates to WP6. The equilibrium constants were determined by an analysis of the absorption spectra. It was found that the acidity of the phenol form merocyanines were largely reduced on complexation, pKa shifts of 1.1–1.6 units were observed. In neutral solutions, the complexes of the phenol forms of M1 and M2 were dominant, in contrast to the more acidic M3 (a dibromo derivative), of which the phenolate complex was more stable. Comparing the spectral properties, the binding constants and the pKa-s of the dye-WP6 complexes, the complex M3?WP6 was chosen to be tested as a displacement assay. It was demonstrated that this complex functioned as a colorimetric indicator displacement assay which discriminated trimethyl lysine from other lysine derivatives.
Isomerizable N-Alkylmerocyanine Dyes as Probes of Micellar Solubilization Sites
Dennis, K. Jason,Luong, Thiem,Reshwan, Mary L.,Minch, Michael J.
, p. 8328 - 8335 (2007/10/02)
The thermal cis to trans isomerization of N-alkylmerocyanine dyes is catalyzed by both cationic and anionic micelles.The catalysis by cationic micelles of hexadecyltrimethylammonium bromide (CTABr) increases markedly with substrate N-alkyl group length and is exceptionally pronounced for N-alkyl groups larger than pentyl.Rate data fit the pseudophase model of micellar catalysis for CTABr concentrations between 0.005 and 0.1 M and binding constants (KS) and micellar rate constants (km) were evaluated.Both KS and kmincreased dramatically as the N-alkyl group was varied from N-methyl to N-pentyl so that the increase in catalysis with substrate hydrophobicity is due not only to increased substrate binding to the micelle but also to enhanced reactivity within the micelle.At CTABr concentrations greater than 0.1 M, km is not constant but increases, reflecting changes in micelle structure at bigh surfactant concentration.Eyring activation parameters were determined for the overall rate constant.The increase in reactivity as a function of N-alkyl group hydrophobicity was shown to be due primarily to an increase in ΔS.
Thermal Cis-Trans Isomerization of Solvatochromic Merocyanines: Linear Correlations between Solvent Polarity and Adiabatic and Diabatic Transition Energies
Abdel-Halim, Shakir T.,Abdel-Kader, Mahmoud H.,Steiner, Ulrich E.
, p. 4324 - 4328 (2007/10/02)
The correlation between solvatochromy and the sovent-polarity-dependent rate constant kct of thermal cis-trans isomerization (solvatokinetic behavior) has been investigated for a stilbazolium-type merocyanine and an amphiphilic analogue in a polarity series of eight neat solvents (protic and aprotic).At room temperature kct varies over 7 orders of magnitude, decreasing with increasing solvent polarity.It has been demonstrated that the first transition energy ΔEmax and the free activation enthalpy ΔG(excit.)ct of thermal cis-trans isomerization are linearly correlated with each other and with Dimroth's solvent polarity parameter ET.These observations and the sovent-polarity-dependent increase of absorption band width are explained in terms of a model emphasizing the strong coupling between molecular conformation, electronic charge distribution, and solvent polarization.
