•Porphyrin-peptide conjugates were self-assembled into regular nanostructures.•The photophysical properties of the nanoparicles indicate formation of typical J-aggregates.•The Raman spectra confirm that diprotonation of the porphyrin core contributes to exciton coherence in the nanoparticles.In this report, L-diphenylalanine-decorated tetraphenylporphyrin (TPPtFFC) was synthesized and self-assembled into regular nano-architechtures. The morphology of the assemblies varied with the concentration of TPPtFFC. The absorption spectra of the nanoparticles show the Soret band merges with the Q bands and redistributes with great red-shift, indicative of the formation of J-aggregates of the porphyrin molecules. The fluorescence emission of the nanoparticles is merged and red-shifted to near-infrared region. Studies of absorption and fluorescence spectra reveal an indispensible role of diphenylalanine group in the formation of J-aggregates. The Raman spectra disclose that diprotonation of the porphyrin core contributes to delocalized coherent excited states in the nanoparticles. The positive cotton effect in circular dichroism spectra corresponding to the Soret band of TPPtFFC in solution confirms the formation of J-aggregates with right-handed chirality of the dipole moment. This report will shed light on the rational design of porphyrin-peptide conjugates to mimic naturally light-harvesting complexes.TPPtFFC was synthesized and self-assembled into regular nano-architectures. Photophysical property studies of the nanoparticles indicate the porphyrin molecules form typical J-aggregates. The diprotonation of the porphyrin core and the FF group play an indispensible role in the formation of J-aggregates.Download high-res image (167KB)Download full-size image

•The five triphenylamine derivatives modified by benzoylhydrazone structure were synthesized.•The effects of the electron-withdrawing/donating group were confirmed by density functional study and photophysical properties.•The thermostability and electrochemistry properties of the five compounds were found to be distinctively promoted.A novel of triphenylamine derivatives with more extended π-conjugated systems achieved by benzoylhydrazone architecture were synthesized under mild condition with high yields. The dependence of their photophysical, electrochemistry and thermal properties on their chemical structure is discussed. Compared with the N,N-di(4-methylphenyl)aniline, the thermostability of the five triphenylamine-based hydrozones is dramatically promoted. These compounds are stable up to 345 °C according to thermogravimetric analysis. The energy levels of the four compounds were finely tuned by introducing the electron-donating and -withdrawing groups to the triphenylamine core which are supported by the fluorescence spectra and transit fluorescence spectra of the compounds (–H > –CH3 > –Cl > Pyridine > –NO2). Their multiple cyclic voltammetry study and density functional study suggest these materials to be promising hole-transport properties.

•4-[N, N-di(4-tolyl)amino] benzaldehyde-2-chloro benzoylhydrazone were synthesized and characterized.•The photophysical, thermostability properties of the titled compound were found to be distinctively modified by benzoylhydrazone structure.•DFT calculations and experimental results were coincided on structure, energy gap and electrochemistry.•The hydrogen bonding interactions within sheets and π–π interactions 3D network confirmed the title compound can be used as amorphous material in nonpolar solvents.The title compound 4-[N, N-di(4-tolyl)amino] benzaldehyde-2-chloro benzoylhydrazone (C28H24ClN3O, Mr = 453.96) was synthesized by the reaction of 4-[N, N-di(4-tolyl)amino] benzaldehyde with 2-chlorobenzohydrazide, and its structure was characterized by IR, 1H NMR, 13H NMR, high-resolution mass spectrometry and single-crystal X-ray diffraction. The crystal belongs to Monoclinic, space group P2(1)/n with a = 12.626(3), b = 12.609(3), c = 15.837(3) Å, β = 90.00(3)°, Z = 5, V = 2512.5(9) Å3, Mr = 453.95, Dc = 1.280 g/cm3, μ = 0.183 mm−1, F(0 0 0) = 1024, R = 0.0432 and wR = 0.1087. X-ray analysis revealed that one of the benzene ring and acylhydrazone were essentially planar, the 2-chloro benzene ring and amide were non-planar, the torsion angles C(1)C(6)C(7)O(1) and C(5)C(6)C(7)O(1) are 61.4(5)° and −114.4(4)°. The thermal stability studies indicate that the title compound is stable up to 341.1 °C. The spectral, electrochemistry properties and theoretical studies show that the title compound is a good candidate for the charge-transporting materials.

•The oxidation of tiopronin by cis-[Pt(NH3)2Cl4] and trans-[PtCl2(CN)4]2 − was studied.•Tiopronin was oxidized to tiopronin disulfide exclusively.•A general rate law was established over a wide pH range.•A detailed reaction mechanism is proposed accordingly.Tiopronin, a synthetic thiol-containing drug being used in treatments of cystinuria and certain types of rare arthritis, is also a hepatoprotective and a detoxifying agent. Many analytical methods have been developed based on its redox chemistry with metal ions/complexes, but the kinetic and mechanistic aspects are poorly understood. In this work, the oxidation of tiopronin by cisplatin prodrug and a model compound, cis-[Pt(NH3)2Cl4] and trans-[PtCl2(CN)4]2 −, was investigated. The oxidation kinetics was followed by a stopped-flow spectrophotometer over a wide pH range under the pseudo first-order conditions of [Tiopronin]≫[Pt(IV)]. Time-resolved spectra were also recorded for both Pt(IV) complexes, enabling to establish an overall second-order rate law: − d[Pt(IV)] / dt = k′[Tiopronin][Pt(IV)], where k′ pertains to observed second-order rate constants. Under the kinetic conditions, tiopronin was oxidized to form the tiopronin-disulfide exclusively as identified by mass spectrometry. A reaction mechanism was proposed, involving parallel reductions of the Pt(IV) complexes by the three protolytic tiopronin species as rate-determining steps. The rate constants for the rate-determining steps were derived. The fully deprotonated tiopronin is about 4 × 104 more reactive than its corresponding thiol form for both Pt(IV) complexes; the huge reactivity difference orchestrates closely with the fact that the nucleophilicity of thiolate is much higher than the corresponding thiol. Hence, the attack of the sulfur atom in thiol/thiolate of tiopronin on the axially-coordinated chloride in the Pt(IV) complexes is nucleophilic in nature in the rate-determining steps, resulting in a bridge formation and a subsequent bridged electron-transfer.Second-order rate constants k′ as a function of pH at 25.0 °C and ionic strength of 1.0 M for oxidation of tiopronin by cis-[Pt(NH3)2Cl4] and trans-[PtCl2(CN)4]2 − (data points were obtained). The solid curve was obtained by fitting Eq. (6) the experimental data by use of a weighed nonlinear least-squares method.

Thioredoxins are small redox proteins and have the active sites of Cys-Xaa-Yaa-Cys; they are overexpressed by many different cancer cells. Cisplatin and Pt(II) analogues could bind to the active sites and inhibit the activities of the proteins, as demonstrated by other researchers. Platinum(IV) anticancer drugs are often regarded as prodrugs, but their interactions with thioredoxins have not been studied. In this work, 3,6-dioxa-1,8-octanedithiol (dithiol) was chosen as a model compound for the active sites of thioredoxins, and its reactions with cis-[Pt(NH3)2Cl4] and trans-[PtCl2(CN)4]2– (cisplatin prodrug and a model complex) were studied. The pKa values for the dithiol were characterized to be 8.7 ± 0.2 and 9.6 ± 0.2 at 25.0 °C and an ionic strength of 1.0 M. The reaction kinetics was followed by a stopped-flow spectrophotometer over a wide pH range. An overall second-order rate law was established, −d[Pt(IV)]/dt = k′[Pt(IV)][dithiol], where k′ stands for the observed second-order rate constants. Values of k′ increased several orders of magnitude when the solution pH was increased from 3 to 9. A stoichiometry of Δ[Pt(IV)]/Δ[dithiol] = 1:1 derived for the reduction process and product analysis by mass spectrometry indicated that the dithiol was oxidized to form an intramolecular disulfide, coinciding with the nature of thioredoxin proteins. All of the reaction features are rationalized in terms of a reaction mechanism, involving three parallel rate-determining steps depending on the pH of the reaction medium. Rate constants for the rate-determining steps were evaluated. It can be concluded that Pt(IV) anticancer prodrugs can oxidize the reduced thioredoxins, and the oxidation mechanism is similar to those of the oxidations of biologically important reductants by some reactive oxygen species (ROS) such as hypochlorous acid/hypochlorite and chloramines.

Porphyrins bearing naphthyl group were synthesized to afford expanded π-conjugated systems and were characterized by 1H NMR, IR, FAB-MS and UV–vis spectra. The fluorescence spectra illustrate that the maximal excitation and emission wavelengths of naphthylporphyrins were red shifted with 3–6 nm compared with that of H2TPP. The cyclic voltammetric results of 8 kinds of naphthylporphyrin are firstly reported. Several porphyrin–anthraquinone dyads were synthesized and their molecular energy levels were obtained from the multilevel ionization potential (IP) and electron affinity (EA) according to the redox potential. Photoinduced intramolecular electron transfer occurred from porphyrin ring to anthraquinone moiety, which was confirmed by fluorescence quenching and molecular energy level changing.