General approach for fabricating nanoparticle arrays via patterned block copolymer nanoreactors

A general approach to fabricate nanoparticle arrays of different kinds of materials is demonstrated in this paper. It was found that the center-to-center distance of the nanoparticles or the nanoclusters can be controlled using patterned block copolymer nanoreactors by adding polystyrene (PS) homopolymer to poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) diblock copolymer thin film. The number of the nanoparticles formed in the P4VP nanodomains can also be adjusted by addition of polystyrene (PS) homopolymer to poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) diblock copolymer. In fabrication of Au nanoparticle arrays, HAuCl₄ precursor was directly loaded into P4VP nanodomains of the diblock copolymer thin film by using a methanol solvent, which is a good solvent for P4VP but non-solvent for PS. The Au nanoparticle arrays were then obtained by reducing HAuCl₄ with sodium citrate dihydrate, and then in situ transferred to silicon substrate by a two-step calcination method. ZnO and Fe _x O _y nanoparticle arrays were also synthesized by this approach with thermal decomposition and double decomposition reactions, respectively. Additionally, the advantage of using two-step calcination method over the air plasma method was discussed.     

Formation of Sn@C Yolk–Shell Nanospheres and Core–Sheath Nanowires for Highly Reversible Lithium Storage

As one promising anode material with high theoretical capacity, metallic tin has attracted much research interest in the field of lithium‐ion batteries. Here, two types of tin/carbon (Sn@C) core–shell nanostructures with inner buffering voids are fabricated from SnO₂ hollow nanospheres via a facile chemical vapor deposition (CVD) method. The crystallinity and surface topography of SnO₂ hollow nanospheres are found to affect the morphology of resultant Sn@C materials. Sn@C yolk–shell nanospheres and core–sheath nanowires are obtained from the as‐prepared SnO₂ and high‐temperature annealed SnO₂ nanospheres, respectively. The unique Sn@C nanostructures can mitigate the agglomeration/pulverization of Sn nanoparticles and electrical disconnection from the current collector caused by the large volume change during the lithium alloying/dealloying process. Both Sn@C yolk–shell and core–sheath nanostructures show stable cycling performance up to 500 cycles with specific capacities of ca. 430 and 520 mA h g^?1, respectively.     

α-Fe2O3 and Fe3O4 hollow nanospheres as high-capacity anode materials for rechargeable Li-ion batteries

α-Fe₂O₃ and Fe₃O₄ hollow nanospheres of size 30?±?2 nm were synthesized by using polymeric micelles as a soft template for the first time. The hollow nanospheres were thoroughly characterized by transmission electron microscope, superconducting quantum interference device, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, cyclic voltammogram, and nitrogen sorption analyses. The α-Fe₂O₃ and Fe₃O₄ hollow nanospheres were used as anode materials in lithium-ion rechargeable batteries to investigate their electrochemical properties. The hollow particle-based electrodes exhibit high capacity, stable cycling performance, and good rate capability at different current densities. The α-Fe₂O₃ and Fe₃O₄ hollow nanospheres with nanosized shell domain favors fast lithium insertion/extraction processes during the repeated charge/discharges.     

Controlled synthesis of cuprous oxide nanospheres and copper sulfide hollow nanospheres

Uniform Cu₂O nanospheres have been successfully synthesized by reducing CuSO₄ with ascorbic acid in sucrose solution at room temperature. The diameter of the Cu₂O nanospheres can be tuned from 90 to 280 nm by adding different amounts of sucrose in the solution. Furthermore, CuS hollow nanospheres with different diameters have been obtained based on the Kirkendall effect using the as-prepared Cu₂O nanospheres as sacrificial templates. Cu₂O/Cu_7.2S₄ core/shell nanospheres and Cu_7.2S₄ hollow nanospheres are obtained as the intermediate products at different stages of the conversion process. Through the post-treatment of sodium citrate solution, Cu_7.2S₄ hollow nanospheres can be changed into CuS hollow nanospheres. The products are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM). Optical properties of the products have also been studied.     

Reduced Graphene Oxide decorated with Manganese Cobalt Oxide as Multifunctional Material for Mechanically Rechargeable and Hybrid Zinc–Air Batteries

Spinel MnCo₂O₄ nanoparticles on nitrogen‐doped reduced graphene oxide (MnCo₂O₄/NGr) are synthesized for advanced zinc–air batteries with remarkable cyclic efficiency and stability. The synthesized MnCo₂O₄/NGr exhibits good oxygen‐reduction reaction (ORR) activity with half‐wave potential E _1/2 of 0.85 V (vs reversible hydrogen electrode (RHE)), comparable to commercial Pt/C with E _1/2 of 0.88 V (vs RHE) along with superior oxygen electrode activity ΔE = 0.91 V for the ORR/OER (oxygen‐evolution reaction) in alkaline media. Durability tests confirm that MnCo₂O₄/NGr is more stable than Pt/C in alkaline environment. MnCo₂O₄/NGr functions with stable discharge profile of 1.2 V at 20 mA cm^?2, large discharge capacity of 707 mAh g^?1_Zn at 40 mA cm^?2 and a high energy density of 813 Wh kg^?1_Zn in a mechanically rechargeable zinc–air battery. The electrically rechargeable MnCo₂O₄/NGr zinc–air battery displays hybrid behavior with both Faradaic and oxygen redox charge–discharge characteristics, operating at higher voltage and providing higher power density and excellent cyclic efficiency of 86% for over 100 cycles compared to Pt/C with efficiency of around 60%. Moreover, hybrid zinc–air battery operates with a stable and energy efficient profile at different current densities.     

The attachment of amino fragment to purine: inner‐shell structures and spectra

The impact of the amino fragment (–NH₂) attachment on the inner‐shell structures and spectra of unsubstituted purine and the purine ring of adenine are studied. Density functional theory calculations, using the LB94/TZ2P//B3LYP/TZVP model, reveal significant site‐dependent electronic structural changes in the inner shell of the species. A condensed Fukui function indicates that all of the N and C sites, except for N₍₁₎ and C₍₅₎, demonstrate significant electrophilic reactivity (f^? > 0.5 in |e|) in the unsubstituted purine. Once the amino fragment binds to the C₍₆₎ position of purine to form adenine, the electrophilic reactivity of these N and C sites is greatly reduced. As expected, the C₍₆₎ position experiences substantial changes in energy and charge transfer, owing to the formation of the C—NH₂ bond in adenine. The present study reveals that the N1s spectra of adenine inherit the N1s spectra of the unsubstituted purine, whereas the C1s spectra experience significant changes although purine and adenine have geometrically similar carbon frames. The findings also indicate that the attachment of the NH₂ fragment to purine exhibits deeply rooted influences to the inner‐shell structures of DNA/RNA bases. The present study suggests that some fragment‐based methods may not be applicable to spectral analyses in the inner shell.     

Micelles of poly(isoprene-b-2-vinylpyridine-b-ethylene oxide) terpolymers in aqueous media and their interaction with surfactants

Well-defined poly(isoprene-b-2-vinylpyridine-b-ethylene oxide) (PI-P2VP-PEO) triblock terpolymers were synthesized by anionic polymerization high-vacuum techniques. The terpolymers formed spherical three-layer (onion-type) micelles in neutral and acidic pH aqueous media as evidenced by static and dynamic light scattering. In pure water, kinetically frozen micelles with a core composed of a soft PI inner part and a hard P2VP outer shell and protected by a neutral PEO corona were formed. In acidic media the core was formed by the soft PI hydrophobic segment, whereas the corona consisted of an inner cationic polyelectrolyte P2VPH⁺ part and an outer PEO shell. The aggregation numbers were found to be high in all cases, due to the high hydrophobicity of the core-forming blocks. In the latter case an increase in size was observed due to the electrostatic repulsions between the P2VPH⁺ chains in the inner part of the corona, which is also responsible for the lower aggregation numbers observed in the acidic solutions. The interaction of these onion-type micelles with cationic (DTMAB) and anionic (SDS) surfactants led to the formation of mixed polymer/surfactant aggregates. Their structural characteristics could be varied by combining changes in surfactant type and concentration, solution pH and type of electrostatic interaction, leading to interesting, block-copolymer-based, environmentally responsive colloidal systems.     

Application of Inverse Laplace Transformation Method for Analysis of Plasma Emission Formed by Laser Ablation of Pb‐Bi‐Sr‐Ca‐Cu‐O

The inverse Laplace transformation method was used to interpret the time‐resolved emission spectra of Sr* and describe the dynamics of the laser plume formed in the laser ablation of Pb‐Bi‐Sr‐Ca‐Cu‐O. Three kinds of processes characterized by rate constants b₁, b₂ and b₃ were found in the laser plume. The rate constant of the slowest process b₃ increases with the pressure and can be assigned to deexcitation of Sr*. The next two rate constants b₁ and b₂ describe processes occurring during the laser pulse and immediately after it.     

Uniform Fe3O4–PANi/PS composite spheres with conductive and magnetic properties and their hollow spheres

Core–shell multifunctional composite spheres consisting of Fe₃O₄–polyaniline (PANi) shell and polystyrene (PS) core were fabricated using core–shell-structured sulfonated PS spheres (with uniform diameter of 250 nm) as templates. PANi was doped in situ by sulfonic acid resulting the composite spheres are well conductive. Dissolved with solvent, PS cores were removed from the core–shell composite spheres and hollow Fe₃O₄–PANi spheres were obtained. Removing the PANi and PS components by calcinations produced hollow Fe₃O₄ spheres. The cavity size of the hollow spheres was uniformly approximate to 190 nm and the shell thickness was 30 nm. The cavity size and the shell thickness can be synchronously controlled by varying the sulfonation time of the PS templates. The shell thickness in size range was of 20–86 nm when the sulfonation time was changed from 1 to 4 h. These resulting spheres could be arranged in order by self-assembly of the templates. Both the Fe₃O₄–PANi/PS composite spheres and the hollow Fe₃O₄ spheres exhibit a super-paramagnetic behavior. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder scattering were used to characterize these as-prepared spheres. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

One-pot synthesis of hybrid nanospheres with multistructure for selective adsorption of Hg<Superscript>2+</Superscript>

Novel complex nanospheres with core/shell structure for selective adsorption of Hg²⁺ have been prepared by a simple one-pot method. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images showed the nanospheres had perpendicularly thiol-functionalized mesoporous SiO₂ hybrid shell and Fe₃O₄@SiO₂ core (Fe₃O₄@nSiO₂@mSiO₂–SH). XRD patterns of as-synthesized nanospheres confirmed the observation of the SEM and TEM. The size of the nanospheres is about 100 nm. Based on the analysis of N₂ sorption–desorption isotherm, the surface area and pore volume of the adsorbent are 861 m²/g and 0.48 cm³/g, respectively. The saturation magnetization value for Fe₃O₄@nSiO₂@mSiO₂–SH is as high as 6.87 emu g⁻¹. The nanospheres showed more accessible active sites and high dispersibility in water, exhibited excellent performance for selective Hg²⁺ adsorption, had a stable structure, and could be recycled easily with magnet.     

EPMA mapping method for small particles of Al3Fe,Al6Fe, α‐AlFeSi and β‐AlFeSi in 1050‐H18 aluminum sheets

We developed an EPMA mapping method for small Al_aFe_bSi_c particles in 1050‐H18 aluminum sheet, which is one of the base materials coated by photoresist in advance called PS plate (pre‐sensitized printing plate). In this method, we used the ratios of relative x‐ray intensities, I_Fe/I_Al and I_Fe/I_Si instead of the mass ratios, Fe/Al and Fe/Si, of the main elements which constitute the particles and tried to determine the ratios of relative x‐ray intensities using Monte Carlo calculations. Furthermore, using this developed mapping method, we performed the mapping of small Al_aFe_bSi_c particles such as Al₃Fe (0–3%Si as impurities), Al₆Fe (0–1%Si as impurities), α‐AlFeSi(Al_8.3Fe₂Si) and β‐AlFeSi(Al_8.9Fe₂Si₂) in 1050‐H18 aluminum sheets. We found that the discrimination of these particles was achieved with this mapping method. We confirmed that this method is useful for the mapping of Al_aFe_bSi_c particles in 1050‐H18 aluminum sheets. Copyright © 2004 John Wiley & Sons, Ltd.     

Piperidine‐appended imidazolium ionic liquids as task‐specific catalysts: computational study,synthesis, and multinuclear NMR

Imidazolium ionic liquids (IMILs) with a piperidine moiety appended via variable length methylene spacers (with n = 1–4) were studied computationally to assess their potential to act as internal base for N‐heterocyclic carbene (NHC) generation. Proton transfer energies computed by B3LYP/6‐311+G(2d,p) were least endothermic for the basic‐IL with n = 3, whose optimized structure showed the shortest C₂‐H‐‐‐‐N(piperidine) distance. Inclusion of counter anion (Cl or NTf₂) caused dramatic conformational changes to enable close contact between the acidic C₂‐H and the anions. To examine the prospect for internal C₂‐H‐‐‐‐N coordination, multinuclear NMR data (¹H, ¹⁵N, and ¹³C) were computed by gauge independent atomic orbitals–density functional theory (GIAO‐DFT) in the gas phase and in several solvents by the PCM method for comparison with the experimental NMR data for the basic ILs (with n = 2–4) synthesized in the laboratory. These studies indicate that interactions with solvent and counter ion are dominant forces that could disrupt internal C₂‐H‐‐‐‐N coordination/proton transfer, making carbene generation from these basic‐ILs unlikely without an added external base. Therefore, the piperidine‐appended IMILs appear suitable for application as dual solvent/base in organic/organometallic transformations that require the use of mild base, without the necessity to alkylate at C‐2 to prevent N‐heterocyclic carbene formation. Copyright © 2016 John Wiley & Sons, Ltd.     

Hartree–Fock and density functional theory study of remote substituent effects on heterolytic Fe–N bond energies of p‐G‐C6H4NHFe(CO)2(η5‐C5H5) and p‐G‐C6H4N(COMe)Fe(CO)2(η5‐C5H5)

The nature and strength of metal–ligand bonds in organotransition‐metal complexes are crucial to the understanding of organometallic reactions and catalysis. Quantum chemical calculations at different levels of theory have been used to investigate heterolytic Fe–N bond energies of para‐substituted anilinyldicarbonyl(η⁵‐cyclopentadienyl)iron [p‐G‐C₆H₄NH(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄NHFp (1), where G = NO₂, CN, COMe, CO₂Me, CF₃, Br, Cl, F, H, Me, MeO, and NMe₂] and para‐substituted α‐acetylanilinyldicarbonyl(η⁵‐cyclopentadienyl)iron [p‐G‐C₆H₄N(COMe)(η⁵‐C₅H₅)Fe(CO)₂, abbreviated as p‐G‐C₆H₄N(COMe)Fp (2)] complexes. The results show that BP86 and TPSSTPSS can provide the best price/performance ratio and more accurate predictions in the study of ΔH_het(Fe–N)'s. The linear correlations [r = 0.98 (g, 1a), 0.93 (g, 2b)] between the substituent effects of heterolytic Fe–N bond energies [ΔΔH_het(Fe–N)'s] of series 1 and 2 and the differences of acidic dissociation constants (ΔpK_a) of N–H bonds of p‐G‐C₆H₄NH₂ and p‐G‐C₆H₄NH(COMe) imply that the governing structural factors for these bond scissions are similar. And the linear correlations [r = ?0.99 (g, 1c), ?0.92 (g, 2d)] between ΔΔH_het(Fe–N)'s and the substituent σ_p^? constants show that these correlations are in accordance with Hammett linear free energy relationships. The polar effects of these substituents and the basis set effects influence the accuracy of ΔH_het(Fe–N)'s. ΔΔH_het(Fe–N)'s(1, 2) follow the captodative principle. ME_{α‐COMe, para‐G}s include the influences of the whole molecules. The correlation of ME_{α‐COMe, para‐G}s with σ_p^? is excellent. ME_{α‐COMe, para‐G}s rather than ΔΔH_het(Fe–N)'s in series 2 are more suitable indexes for the overall substituent effects on ΔH_het(Fe–N)'s(2). Insight from this work may help the design of more effective catalytic processes. Copyright © 2012 John Wiley & Sons, Ltd.     

Polymeric Micelles Employing Platinum(II) Linker for the Delivery of the Kinase Inhibitor Dactolisib

Polymeric micelles are attractive nanocarriers for hydrophobic drug molecules such as the kinase inhibitor dactolisib. Two different poly(ethylene glycol)–poly(acrylic acid) (PEG‐b‐PAA) block‐copolymers are synthesized, PEG(5400)‐b‐PAA(2000) and PEG(10000)‐b‐PAA(3700), respectively. Polymeric micelles are formed by self‐assembly once dactolisib is conjugated via the ethylenediamine platinum(II) linker (Lx) to the PAA block of the block copolymers. Dactolisib micelles with dactolisib loading content of 17% w/w show good colloidal stability and display sustained release of Lx‐dactolisib over 96 h in PBS at 37 °C, while media containing reagents that compete for platinum coordination (e.g., glutathione (GSH) or dithiothreitol (DTT)) effectuate release of the parent inhibitor dactolisib at similar release rates. Dactolisib/lissamine‐loaded micelles are internalized by human breast adenocarcinoma cells (MCF‐7) in a dose and time‐dependent manner as demonstrated by confocal microscopy. Dactolisib‐loaded micelles inhibit the PI3K/mTOR signaling pathway at low concentrations (400 × 10^?9 m ) and exhibit potent cytotoxicity against MCF‐7 cells with IC₅₀ values of 462 ± 46 and 755 ± 75 × 10^?9 m for micelles with either short or longer PEG‐b‐PAA block lengths. In conclusion, dactolisib loaded PEG‐b‐PAA micelles are successfully prepared and hold potential for nanomedicine‐based tumor delivery of dactolisib.     

High‐temperature stability of Au/p‐type diamond Schottky diode

Rectification properties of Au Schottky diodes were investigated in high‐temperature operation. These diodes were fabricated on a p‐type diamond single crystal using the vacuum‐ultraviolet light/ozone treatment. The ideality factor n of the Schottky diodes decreased monotonically with increasing measurement temperature whereas the Schottky barrier height ?_b increased, and ?_b reached 2.6 eV at 550 K with n of 1.1. Through high temperature heating at 870 K, the mean value of ?_b at 300 K changed permanently from 2.2 eV to 1.1 eV. Decrease of ?_b might originate from a dissolution of oxygen termination at the Au/diamond interface. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Co3O4@Co Nanoparticles Embedded Porous N‐Rich Carbon Matrix for Efficient Oxygen Reduction

Oxygen reduction reaction (ORR) is an important reaction in many energy conversion systems, but it is severely restricted by its slow kinetics. Developing efficient non‐noble‐metal catalysts for ORR has attracted extended interests, but still remains a great challenge. Herein, an efficient catalysts consisting of Co₃O₄@Co nanoparticles embedded in N‐rich mesoporous carbon matrix is developed by the carbonization of Co‐containing zeolitic imidazolate framework precursor. The derived matrix exhibits outstanding catalytic activity with onset potential of 0.97 V vs. RHE, half‐wave potential of 0.88 V vs. RHE, and good catalytic durability when tested with the rotation speed of 1600 rpm. Carbinization under NH₃ introduces extra elemental N, which subsequently enhances the limiting current densities. This study provides insight into the rational design of highly active ORR catalysts.     

Surface‐enhanced Raman scattering of 4‐aminobenzenethiol on silver: confirmation of the origin of b2‐type bands

In order to resolve the dispute on the origin of the b₂‐type bands in the surface‐enhanced Raman scattering (SERS) of 4‐aminobenzenethiol (4‐ABT), we have measured its SERS spectra under a variety of conditions, including variable temperature and rotation, electrochemistry, and pH, as well as in the presence of a reducing agent. For comparison, the SERS spectra of 4‐nitrobenzenethiol (4‐NBT) and methyl orange (MO), a prototype azo compound, were also measured. First, we found that 4‐ABT on Ag is not subjected to photoreaction, although 4‐NBT is highly photoreactive on a silver surface. In the electrochemical environment, b₂‐type bands of 4‐ABT lost their intensity at very negative potentials, but the intensity recovered immediately upon raising the potential. In addition, b₂‐type bands were observed under rotation even after lowering the potential. The disappearance and reappearance of the b₂‐type bands could also be observed by bringing the sample of 4‐ABT on Ag into contact consecutively with a borohydride solution and water. This is because the surface potential of Ag is lowered by contact with a borohydride solution. Besides, we found that not only the normal Raman but also the SERS spectral features of 4‐ABT are hardly affected by pH variation, while the spectral features of MO are greatly affected, especially in the region of the NN stretching vibration, suggesting that the possibility of a photoconversion of 4‐ABT to an azo compound is low. Altogether, the b₂‐type bands were attributed to 4‐ABT, appearing in conjunction with the chemical enhancement mechanism in SERS. Copyright © 2011 John Wiley & Sons, Ltd.     

Substituent effects on the 13C NMR chemical shifts of the imine carbon in N‐(4‐X–benzylidene)‐4‐(4‐Y–styryl) anilines

Long‐range electronic substituent effects were targeted using the substituent dependence of δ_C(C═N), and specific cross‐interactions were explored extendedly. A wide set of N‐(4‐X–benzylidene)‐4‐(4‐Y–styryl) anilines, p‐X–C₆H₄CH═NC₆H₄CH═CHC₆H₄–p‐Y (X = NMe₂, OMe, Me, H, Cl, F, CN, or NO₂; Y = NMe₂, OMe, Me, H, Cl, or CN) were prepared for this study, and their ¹³C NMR chemical shifts δ_C(C═N) of C═N bonds were measured. The results show that both the inductive and resonance effects of the substituents Y on the δ_C(C═N) of p‐X–C₆H₄CH═NC₆H₄CH═CHC₆H₄–p‐Y are less than those of the substituents Y in p‐X–C₆H₄CH═NC₆H₄–p‐Y. Moreover, the sensitivity of the electronic character of the C═N function to electron donation/electron withdrawal by the substituent X or Y attenuates as the length of the conjugated chain is elongated. It was confirmed that the substituent cross‐interaction is an important factor influencing δ_C(C═N), not only when both X and Y are varied but also when either X or Y is fixed. The long‐range transmission of the specific cross‐interaction effects on δ_C(C═N) decreases with increasing conjugated distance between X and Y. The results of this study suggest that there is a long‐range transmission of the substituent effects in p‐X–C₆H₄CH═NC₆H₄CH═CHC₆H₄–p‐Y. Copyright © 2012 John Wiley & Sons, Ltd.     

A novel probe for determination of electrical surface potential of surfactant micelles: N,N'‐di‐n‐octadecylrhodamine

The peculiarities of the structure of the fluorescent dye N,N'‐di‐n‐octadecylrhodamine advantage its using as an interfacial acid–base probe in aqueous micellar solution of colloidal surfactants. Two long hydrocarbon tails of the dye provide similar orientation of both cation and zwitterion on the micelle/water interface, with the ionizing group COOH exposed to the Stern region in all the systems studied. Further, the charge type of the acid–base couple, A⁺B^±, ensures similar values of the ‘intrinsic’ contribution, pK, to the ‘apparent’ pK value in micelles of different surfactants. This makes the indicator suitable for determination of electrical surface potentials, Ψ. The pKs have been obtained in cationic, anionic, zwitterionic, and nonionic surfactant systems, at various salt background. In total 17 systems were studied. At bulk counterion concentration of ca. 0.05 M, the pK values vary from 2.14 ± 0.07 in n–C₁₈H₃₇N(CH₃)Cl^– micelles to 5.48 ± 0.06 in n–C₁₆H₃₃OSONa⁺ micelles. The Ψ values, corresponding to the Stern region of micelles, have been evaluated as Ψ = 59.16 pK–pK for T = 298.15 K. The pK parameter was equated to the average value of 4.23 in nonionic surfactants (4.12–4.32, depending on the surfactant type). For cetyltrimethylammonium bromide and sodium n‐dodecylsulfate micelles, the Ψ values (±(7–11) mV) appeared to be +118 mV and at bulk Br^? concentration 0.019 M and ?76 mV at bulk Na⁺ concentration 0.020 M, respectively. This satisfactorily agrees with the theoretical values +111 and ?84 mV, estimated using the Oshima, Healy, and White equation for these well‐defined colloidal systems. Finally, not only absorption, but also fluorescence spectra display the same response to changes in bulk pH. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,properties, and solvatochromism of 1,3‐dimethyl‐5‐{(thien‐2‐yl)‐[4‐(1‐piperidyl) phenyl]methylidene}‐(1H,3H)‐pyrimidine‐2,4,6‐trione

A new merocyanine dye, 1,3‐Dimethyl‐5‐{(thien‐2‐yl)‐[4‐(1‐piperidyl)phenyl]methylidene}‐ (1H, 3H)‐pyrimidine‐2,4,6‐trione 3 , has been synthesized by condensation of 2‐[4‐(piperidyl)benzoyl]thiophene 1 with N,N′‐dimethyl barbituric acid 2 . The solvatochromic response of 3 dissolved in 26 solvents of different polarity has been measured. The solvent‐dependent long‐wavelength UV/Vis spectroscopic absorption maxima, v_max, are analyzed using the empirical Kamlet–Taft solvent parameters π* (dipolarity/polarizability), α (hydrogen‐bond donating capacity), and β (hydrogen‐bond accepting ability) in terms of the well‐established linear solvation energy relationship (LSER): (1) The solvent independent coefficients s , a , and b and (v_max)₀ have been determined. The McRae equation and the empirical solvent polarity index, E_T(30) have been also used to study the solvatochromism of 3 . Copyright © 2007 John Wiley & Sons, Ltd.