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An asymmetric Pt(IV) prodrug fac-[Pt (dach)Cl3(OC(=O)CH3)] (dach = 1,2-diaminocyclohexane) was synthesized, and the reduction of the Pt(IV) prodrug by three biological thiols glutathione (GSH), cysteine (Cys) and homocysteine (Hcy) was investigated by a stopped-flow spectrometer. All the reductions were followed by an overall second-order reaction with first-order in both [Pt(IV)] and [thiol]. The reduction of the Pt(IV) prodrug occurred through a chloride bridge (Pt-Cl-S) mediated two electron transfer process. Therefore, the coordinated chloride possesses a better bridging effect than the oxygen atom from the coordinated –CH3COO− of the Pt(IV) prodrug. A reactivity trend of k′Cys > k′GSH > k′Hcy is found, illustrating that the reactivity is followed by the trend of Cys > GSH > Hcy in pH 7.4 buffer. Transition state is formed between the axially coordinated chloride of the platinum(IV) complex and the sulfur atom from the thiol/thiolate group of Cys/Hcy/GSH.

In this study, l-methionine selenoxide (MetSeO) was used as an oxidant for the construction of peptide disulfide bonds. Excellent yields for various disulfide-containing peptides were achieved via the MetSeO oxidation method in different solvents and on a resin. Most importantly, the construction of disulfide bonds can be performed in the trifluoroacetic acid cocktail used for the cleavage of peptides from the resin, which obviates the steps of peptide purification and lyophilization. This facilitates and simplifies the synthesis of disulfide-containing peptides. Kinetic and mechanistic studies of the reaction between MetSeO and dithiothreitol (DTT, a model compound of dicysteine-containing peptide) show that the reaction is first order in both [MetSeO] and [DTT], and a reaction mechanism is proposed that can help us gain insights into the reaction of the oxidative synthesis of disulfide bonds via MetSeO oxidation.

We present a flexible silica-polymer composite optical fiber (SPCOF) inspired by fish lateral lines for underwater perception. The unique movement status of robotic fish and hydroacoustic signal with frequency of 100 Hz are detected.

A wearable device based on an alignment-free photonic chip (AFPC) which consists of optical microfiber and flexible liquid chip for precise human health monitoring was developed. High-fidelity physiological signals and vital signs were detected and extracted for cardiovascular health accessment.

In this study, l-methionine selenoxide (MetSeO) was used as an oxidant for the construction of peptide disulfide bonds. Excellent yields for various disulfide-containing peptides were achieved

Platinum(iv) complexes with a heterocyclic ligand and an ancillary ligand have been investigated and applied for treating various tumour cell lines. Another application of the Pt(iv) complexes in forming peptide disulfide bonds was investigated in this work. For development of Pt(iv) complex chemistry for disulfide bond formation in peptides, two Pt(iv) complexes, [PtCl2(phen)(en)]Cl2 and [PtCl2(bpy)(en)]Cl2, were synthesized and characterized using elemental analysis, ESI-MS and NMR. Subsequently, they were investigated as oxidants for the formation of disulfide bonds in various peptides. Excellent purities and yields of disulfide-containing peptides were achieved when the reactions were carried out in aqueous solution. The reactions were completed rapidly in a wide range of pH values even in acidic medium at room temperature. An intramolecular disulfide bond was formed in each of the peptides in a solution containing two dithiol-containing peptides, making the Pt(iv) complexes useful for generating disulfide-containing peptide libraries. In addition, the two Pt(iv) complexes can be used as oxidants for the synthesis of disulfide bonds on a resin, which is a more convenient method to synthesize disulfide-containing peptides through automation.

Ormaplatin ([Pt(dach)Cl4]) represents one of the three primary structural prototypes of Pt(iv) anticancer-active prodrugs. The reduction of ormaplatin by an extended series of thiols has been studied kinetically in a broad pH range. A novel and remarkable correlation between log kRS- and the thiol dissociation constants pKRSH is disclosed: log kRS- = (0.50 ± 0.02)pKRSH + (0.68 ± 0.13), where kRS- denotes the second-order rate constant of each thiolate towards the reduction of ormaplatin.

A trans-dibromido-Pt(IV) complex [PtBr2(en)2]Br2 was synthesized and evaluated for the synthesis of peptide disulfide bonds in this work. The reactions between the Pt(IV) complex and dicysteine-containing peptides were carried out in various aqueous solutions. As a result, excellent yields with fast reaction rates were achieved. Methionine residue was intact when the Pt(IV) complex reacted with a dicysteine and methionine-containing peptide. 3,6-Dioxa-1,8-octanedithiol (DODT) was selected as a model compound of the dicysteine-containing peptide. Kinetic studies for the reaction between the Pt(IV) complex and DODT were performed in different pH solutions. It is first-order both in [Pt(IV)] and in [DODT]. A reaction mechanism was proposed accordingly. The kinetic and mechanistic results demonstrated that the reaction rate for the formation of peptide disulfide bond via the Pt(IV) oxidation is increased with the increase of pH of the reaction medium. The protolytic constants of the two thiol groups in peptide also play a critical role in reaction rate. On the other hand, kinetic studies demonstrated that the Pt(IV) complex trans-[PtBr2(en)2]2+ can be used in an acidic medium for the purpose of synthesis of disulfide bonds.

Reported here is a new Ni(II) compound, namely {Ni2(L)(bipy)2(H2O)2}n (1 H4L = 6-(3′,4′-dicarboxyl-phenoxy)isophthalic acid, bipy = 4,4′-bipyridine), which has been synthesized via the solvothermal...

Solvothermal reactions of Zn(NO 3 ) 2 , H 2 tdc and bib in the presence of different solvents (DMF = N,N’- dimethylformamide or DMA = N,N’- dimethylacetamide) have given rise to two new coordination polymers, namely [Zn 2 (tdc) 2 (bib) 2 ] n ·2n(H 2 O) ( 1 ) and [Zn(tdc)(bib) 0.5 (H 2 O)] n ( 2 ) (H 2 tdc = 2,5-thiophenedicarboxylic acid, bib = 1, 4-bis(imidazolyl)butane). The structures were determined by single crystal X-ray diffraction and characterized by elemental analysis, powder X-ray diffraction and infrared spectroscopy. Compound 1 exhibits a 4-fold interpenetrated dia topological network, and compound 2 features a 8-fold interpenetrated ths topological network. In addition, thermal stabilities and solid state luminescent properties of these two compounds were also investigated.

Uniform BaWO4:Eu3+ hierarchical submicrospheres have been prepared via a simple hydrothermal route. The as-synthesized BaWO4:Eu3+ particles are well-dispersed with narrow size distribution and are assembled by many tiny nanoparticles. During the synthesis process, the trisodium citrate additive plays a crucial role for the formation of BaWO4:Eu3+ submicrospheres. Under ultraviolet light excitation, the spherical BaWO4:Eu3+ phosphor exhibits much stronger luminescence than that shuttle-like BaWO4:Eu3+ sample prepared without adding trisodium citrate as additive. The spherical luminescent material may find potential applications in fields of lighting, displays, and nanodevices. This simple synthesis route may be extended to prepare other tungstate functional materials with well-defined morphologies.

BaGdF 5 :Ce 3+ , Ln 3+ (Ln=Eu and Tb) nanoparticles with tunable multicolor emission and magnetic property were fabricated by a facile hydrothermal process. The citrate ions as ligand and shape modifier was introduced into the reaction system to modulate the crystal phase and shape of the products. By simply adjusting the relative concentrations of co-doped Eu 3+ /Tb 3+ ions, the multicolor luminescence in BaGdF 5 host lattice is realized successfully. In addition, the BaGdF 5 :Ce 3+ ,Tb 3+ sample shows paramagnetic property at room temperature with mass magnetic susceptibility value of 0.71×10 −4 emu/g Oe. The as-prepared multifunctional nanomaterials may find potential applications in displays and multiple biolabels.

Uniform and well-dispersed barium molybdate (BaMoO 4 ) hierarchical microspheres and microflowers have been successfully synthesized via a hydrothermal route by using sodium dodecyl benzenesulfonate (SDBS) as surfactant. The reaction conditions, including SDBS additive, pH value of the initial solution, as well as reaction temperature, have great effect on the size and morphology of the BaMoO 4 products. The possible formation process of the BaMoO 4 microspheres has been investigated by time-dependent experiments. The as-synthesized BaMoO 4 :Ln 3+ (Ln = Eu, Tb, Dy, and Sm) phosphors show intense characteristic red, green, green–yellow, and orange–red emissions under ultraviolet light excitation, which might find potential applications in the fields of light emitting phosphors, advanced flat panel displays, and light-emitting diodes (LEDs).

Sodium thiosulfate has been utilized as a rescuing agent for relief of the toxic effects of cisplatin and carboplatin. In this work, we characterized the kinetics of reactions of the trans-dichloro-platinum(IV) complexes cis-[Pt(NH3)2Cl4], ormaplatin [Pt(dach)Cl4] and trans-[PtCl2(CN)4]2− (anticancer prodrugs and a model compound) with thiosulfate at biologically important pH. An overall second-order rate law was established for the reduction of trans-[PtCl2(CN)4]2− by thiosulfate, and varying the pH from 4.45 to 7.90 had virtually no influence on the reaction rate. In the reactions of thiosulfate with cis-[Pt(NH3)2Cl4] and with [Pt(dach)Cl4], the kinetic traces displayed a fast reduction step followed by a slow substitution involving the intermediate Pt(II) complexes. The reduction step also followed second-order kinetics. Reductions of cis-[Pt(NH3)2Cl4] and [Pt(dach)Cl4] by thiosulfate proceeded with similar rates, presumably due to their similar configurations, whereas the reduction of trans-[PtCl2(CN)4]2− was about 1,000 times faster. A common reduction mechanism is suggested, and the transition state for the rate-determining step has been delineated. The activation parameters are consistent with transfer of Cl+ from the platinum(IV) center to the attacking thiosulfate in the rate-determining step.

Three new isomeric lanthanide-organic frameworks, namely [Nd(mbdc)(NO3)(H2O)2]n (1), [Sm(mbdc)(NO3)(H2O)2]n (2), and [Tb(mbdc)(NO3)(H2O)2]n (3) (H2mbdc = isophthalic acid), were synthesized through the hydrothermal reactions of Ln(NO3)3 (Ln = Nd, Sm, or Tb) and H2mbdc. Single-crystal X-ray structural analyses reveal that compounds 1–3 have a three-dimensional framework with (3,6)-connected rtl topology. Furthermore, the luminescent properties of 1 and 3 were also investigated at room temperature.

The oxidation of glycine and alanine by bis(dihydrogen-tellurto)argentite(III) ion was studied by stopped-flow spectrophotometery. The reaction is of first order in Ag(III) complex and has less than unit order in glycine and alanine. A plausible mechanism was proposed form the kinetic studies. The rate equations derived from mechanism found to explain all experimental phenomena. The activation parameters with respect to the rate determining step of the mechanism were calculated.

The kinetics and mechanism of the reduction of chromium(VI) by lactic acid (Lac) in aqueous acidic medium was studied with spectrophotometry in a temperature range of 298.15 K~313.15 K. Under the conditions of the pseudo-first order , the observed rate constant increased with the increase in [Lac] and . There is no salt effect. Based on the experimental results, a probable reaction mechanism of oxidation was proposed. The rate equation derived from the mechanism could explain all the experimental phenomena. Activation parameters along with rate constant of the rate-determining step have been evaluated.

Kinetics and mechanism of oxidation of leucine and alanine by Ag(III) complex were studied spectrophotometrically in alkaline medium at constant ion strength. The reaction was in first order with respect to Ag(III) complex and amino acids (leucine, alanine). The second-order rate constant, k−, decreased with the increasing in [OH−] and [IO4−]. A plausible mechanism was proposed from the kinetics study, and the rate equations derived from mechanism can explain all experimental phenomena. The activation parameters were calculated at 298.2 K.

The kinetics and mechanism of oxidation of aspartic acid by the bis(hydrogen periodato) complex of Cu(III), [Cu(HIO6)2]5−, is studied in an alkaline medium. The reaction rate is first order with respect to Cu(III) and fractional order with respect to aspartic acid. The value of the observed rate constant is found to decrease with the increase in concentrations of either OH− or IO4 −. There is a positive salt effect, and the free radical has been determined. In view of these kinetics phenomena, a plausible mechanism is proposed and the rate equations derived from the mechanism can explain all experimental results. The activation parameters along with the rate constants of the rate-determining step are calculated.

L-Selenomethionine (SeMet), the predominant form of selenium acquired from the diet by humans, has been used as a supplement, and exhibit some important functions like cancer prevention and antioxidative defense. Its interactions with Pt(II) anticancer drugs have been characterized, but its redox reactions with platinum(IV) anticancer prodrugs have not been exploited. In this work, the oxidation of SeMet by Pt(IV) anticancer model compounds trans-[PtX2(CN)4](2-) (X = Cl, Br) was characterized. A stopped-flow spectrometer was used to record the rapid scan spectra and to follow the reaction kinetics over a wide pH range. An overall second-order rate law was derived: -d[Pt(IV)]/dt = k'[Pt(IV)][SeMet], where k' pertains to the observed second-order rate constants. The k'-pH profiles showed that k' increased only about 6 times even though the solution pH was varied from 0.25 to 10.5. The redox stoichiometry was determined as Δ[Pt(IV)]/Δ[SeMet] = 1 : (1.07 ± 0.07), suggesting that SeMet was oxidized to selenomethionine selenoxide. The selenoxide together with its hydrated form was identified explicitly by high resolution mass spectral analysis. A reaction mechanism was proposed which encompassed three parallel rate-determining steps relying on the protolytic species of SeMet. Rate constants of the rate-determining steps were obtained from the simulations of the k'-pH profiles. Activation parameters were determined for the reactions of the zwitterionic form of SeMet with the Pt(IV) complexes. A bridged electron transfer process is delineated in the rate-determining steps and several lines of evidence support the bridged electron transfer mode. Strikingly, reduction of [PtX2(CN)4](2-) by SeMet is 3.7 × 10(3)-5.7 × 10(4) times faster than that by L-methionine. Some potential biological consequences resulting from the strikingly fast reduction are discussed.

Kinetics and mechanism of oxidation of 1,4-butanediamine by a Ag(III) complex were studied spectrophotometrically in alkaline medium at constant ion strength. The reaction shows first order with respect to the Ag(III) complex and 1,4-butanediamine respectively. The second order rate constant, k′, increased with the increasing in [OH−], and decreased with the increasing in [IO4−]. A plausible mechanism was proposed from the kinetics study. The rate equations derived from the mechanism can explain all experimental phenomena. The activation parameters were calculated.

The oxidation of leucine, isoleucine and valine by bis(dihydrogen tellurate)argentate(III) ion was studied by stopped-flow technique. It was both first order with respect to Ag(III) complex and amino acids. A plausible mechanism was proposed form the kinetics study. And the rate equations derived from mechanism can explain all experimental phenomena. The activation parameters along with the second order rate constants were calculated.

The oxidation of 6-Aminocaproic acid by Ag(III) complex, dihydroxydiperiodatoargentate(III) (DPA), was studied in alkaline medium. The reaction was first order with respect to Ag(III) complex, and the order with respect to 6-aminocaproic acid was from one to two. A plausible mechanism involving a pre-equilibrium of adduct formation between the complex and reductant was proposed form the kinetics study. The rate equations derived from mechanism can explain all experimental phenomena, and the activation parameters along with rate constants of the rate-determining step were calculated

Captopril, the first pharmaceutical drug designed, synthesized, and used primarily for the treatment of hypertension and congestive heart failure, is an angiotensin-converting-enzyme inhibitor and is also an antioxidant. On the other hand, the kinetic and mechanistic aspects for the oxidation of captopril are not well understood. The oxidation of captopril by cisplatin prodrug and a model compound, cis-[Pt(NH3)2Cl4] and trans-[PtCl2(CN)4]2−, was thus investigated in this work. A stopped-flow spectrometer was employed to follow the oxidation kinetics over a wide pH-range under the pseudo first-order conditions of [captopril] ≫ [Pt(IV)]. The oxidation by the Pt(IV) complexes displayed a second-order character, first-order each in [Pt(IV)] and in [captopril], whereas the metal-ion-catalyzed autooxidation made a very minor contribution to the overall kinetics in acidic media and was negligible in neutral media. Captopril was oxidized to form the captopril-disulfide as identified by ESI mass spectrometry under the conditions of the kinetic measurements. In the proposed reaction mechanism, the Pt(IV) complexes are reduced by the three protolytic captopril species in parallel as rate-determining steps, generating reactive species of chlorothiol and/or sulfenylchloride. The reactive species will be rapidly trapped, either directly or indirectly, by another molecule of captopril to form captopril-disulfide. The rate constants for the rate-determining steps have been derived, demonstrating that the fully deprotonated captopril is about 105 to 106 times more reactive than its corresponding thiol form toward the Pt(IV) complexes.