RSC Advances

Chew, Shin Thung; Lo, Kong Mun; Sinniah, Saravana Kumar; Sim, Kae Shin; Tan, Kong Wai

doi: 10.1039/c4ra11716fpmid: N/A

Four new copper(ii) complexes containing triphenylphosphonium conjugated salicylaldehyde-(4-fluorobenzhydrazone), (L) with the formulation [CuL]Cl(1), [Cu(phen)L]Cl(2), [Cu(bpy)L]Cl(3), [Cu(dmbpy)L]Cl(4), (where L = doubly deprotonated hydrazone; phen = 1,10′-phenanthroline; bpy = 2,2′-bipyridine; dmbpy = 5,5′-dimethyl-2,2′-bipyridine) have been synthesized. The compounds were characterized by spectroscopic methods and, in the case of crystalline products, by X-ray crystallography. The topoisomerase I (topo I) inhibition, DNA binding and cleavage activities and cytotoxicity of the compounds were studied. A DNA relaxation study demonstrated that all the copper complexes successfully inhibit topo I enzyme by binding to topo I as the preferred pathway. Complex 1 is the most active with starting inhibitory concentration ≈20 μM. The planarity of the tridentate hydrazone Schiff base ligand and the diimine co-ligands increase the binding affinity to DNA. The presence of the 1,10′-phenanthroline co-ligand in complex 2 induces plasmid DNA (pBR322) cleavage without exogenous agents. It is noteworthy that the addition of diimine co-ligands to the copper(ii) complex enhanced the cytotoxicity of the compounds, especially against the human prostate adenocarcinoma cell line (PC-3). Complex 2 exhibits the highest activity against PC-3 with the IC50 value of 2.47 ± 0.37 μM. Annexin V/propidium iodide analysis showed that compound 1 induces apoptotic and necrotic cell death, whereas compound 2–4 work mainly through apoptosis.

Park, Ji Young; Jang, Bo Youn; Lee, Chi Hwan; Yun, Hyeong Jin; Kim, Jae Hong

doi: 10.1039/c4ra08271kpmid: N/A

The development of high performance p-type dye sensitized solar cells (DSSCs) is essential for producing tandem configurations that can overcome the theoretical limitations of single-junction DSSCs. This study evaluates a suitable organic dye for producing high performance p-type DSSCs. The photovoltaic properties of the carbazole monomer (MCBZ) and dimer (DCBZ) were examined to determine the effects of the molecular structure of the photosensitizer on the photovoltaic performance. MCBZ absorbs a larger amount of visible light photons with wavelengths between 400 and 600 nm, and provides better p-type DSSCs than conventional coumarin 343-sensitized solar cells. Furthermore, DCBZ exhibits better photovoltaic performance under standard global AM 1.5 solar conditions than the MCBZ-sensitized solar cells because of the synergistic effects of the enhanced electron injection efficiency and reduced charge recombination probability.

Wu, Yunhai; Zhang, Meili; Zhao, Huaiyang; Yang, Shengxin; Arkin, Aynigar

doi: 10.1039/c4ra11737apmid: N/A

Adsorption of two representative anionic dyes (Acid Fuchsine (AF) and Acid Orange II (AO)) using MCM-41 functionalized with amine groups in a mesoporous silica framework (NH2–MCM-41) as the adsorbent was investigated. Characterization of the modified adsorbent was studied by BET, FTIR, XRD and SEM. Various parameters including solution pH, adsorbent dosage, contact time, initial dye concentration and temperature were systematically studied. The results showed that the adsorption process was pH dependent, and the maximum adsorption capacity for AF was approximately 140.60 mg g−1 at pH 2.0 and 25 °C with a NH2–MCM-41 dosage of 2.0 g L−1, and 278.38 mg g−1 for AO at pH 3.0. In single component systems, equilibrium data fitted well the Langmuir and D–R models, suggesting the adsorption to be monolayer and physical in nature. Kinetic studies showed that the adsorption process could be better described by both the Lagergren pseudo-second-order and the Spahn and Schlunder models. Moreover, it was found that the adsorption was governed by film diffusion followed by intraparticle diffusion. Thermodynamic constant values (ΔGo < 0, ΔHo < 0 and ΔSo < 0) demonstrated that the adsorption reactions of AF and AO onto NH2–MCM-41 were feasible, spontaneous and exothermic under the examined conditions. For binary component systems, AF and AO exhibited competitive adsorption onto NH2–MCM-41, and adsorption capacity values of AF and AO were reduced compared to those of the corresponding single component systems. Furthermore, both in single and binary component systems, the experimental data could be better described by the Langmuir isotherm and the pseudo-second-order kinetic models.

Glenneberg, J.; Zenkner, M.; Wagner, G.; Lemm, S.; Ehrhardt, C.; Münchgesang, W.; Buchsteiner, A.; Diestelhorst, M.; Beige, H.; Ebbinghaus, S. G.; Leipner, H. S.

doi: 10.1039/c4ra07354apmid: N/A

We investigated structural and dielectric properties of novel capacitors based on 0–3 composite dielectrics. For this purpose various BaTiO3/Ba(Ti,Ge)O3 nano scaled powders were synthesized via four different routes, namely via the sol–gel procedure, the oxalate method, the Pechini method and the mixed oxide method. As the best-suited method with respect to the formation of spherical and equally sized particles without agglomeration, a sol–gel synthesized powder was chosen for further experiments. The nanoparticles were coated with E glass (CaO, MgO, Al2O3, B2O3, SiO2), BBS glass (BaO, SiO2, B2O3) or an Al2O3/MgO mixture. The resulting composites were annealed, sintered and afterwards covered with electrodes to fabricate ceramic composite capacitors. To identify the system best suited for energy storage applications, different matrices and BaTiO3/matrix ratios were investigated. The morphology and the phase content were analyzed by electron microscopy and X-ray diffraction. An optimum grain size and distribution was obtained for a 15 wt% BBS glass mixed with a Ba(Ti,Ge)O3 powder. The mixture sintered at 925 °C resulted in the best composite dielectrics not only concerning the morphology but also the dielectric data. Additionally, the BBS matrix showed no tendency to form secondary phases, while preserving a homogenous distribution of matrix element components.

Malakhov, Mikhail V.; Dubinnyi, Maxim A.; Vlasova, Natalia V.; Zgoda, Victor G.; Efremov, Roman G.; Boldyrev, Ivan A.

doi: 10.1039/c4ra08106dpmid: N/A

Ozonolysis of furocoumarins followed by reductive work-up yields not only common symmetrical dialdehydes, but also o-formylumbelliferones with moderate-to-high yields. Simultaneous formation of both products accounts for the transformation of carbonyl oxides – products of primary ozonide ring opening.

Wang, Xiao Xiao; Yu, Baoyi; Van Hecke, Kristof; Cui, Guang Hua

doi: 10.1039/c4ra08138bpmid: N/A

Four mixed ligand coordination polymers based on the flexible bis(5,6-dimethybenzimidazole) and aromatic dicarboxylic acids, namely, [Co(L1)(bpdc)]n (1), {[Co(L1)(npht)]·0.5H2O}n (2), [Co(L2)(bpdc)]n (3), and [Co(L3)(bpdc)(H2O)]n (4) (L1 = 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H2bpdc = 4,4′-biphenyldicarboxylic acid, L2 = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H2npht = 3-nitrophthalic acid, L3 = 1,1′-bis(5,6-dimethylbenzimidazole)methane) have been hydrothermally synthesized and structurally characterized. Polymer 1 features a 3D three-fold interpenetrating dia array with a 4-connected 66 network, while 2 exhibits a 3D noninterpenetrated 3-connected framework with a 103-ThSi2 architecture. 3 and 4 have two-dimensional 3-connected (63) and 4-connected (44.62) topologies, respectively. Complex 4 ultimately is extended into an unusual 3D (3,5)-connected seh-3,5-P21/c supramolecular network via O–H⋯O hydrogen bonding interactions. The fluorescence and catalytic properties of the complexes for the degradation of the Congo red azo dye in a Fenton-like process are reported.

Özdemir, Abdil; Lin, Jung-Lee; Wang, Yi Sheng; Chen, Chung-Hsuan

doi: 10.1039/c4ra06409gpmid: N/A

Sonic spray ionization (SSI) has been explored as an ambient ionization method for mass spectrometric analysis of different compounds. It has been applied to the analysis of different groups of compounds, mostly small molecules. The work reported in this paper extends the ionization efficiency of SSI and application of SSI to different groups of compounds, mostly biomolecules, in an ion trap mass spectrometer. SSI does not use any power supply and produces both positive and negative ions simultaneously. The most important parameters in SSI are gas pressure, solvent flow rate and physical dimensions of the spray device. Although the first two parameters have been investigated by different groups, the effect of physical dimensions has not been reported in the literature. Silica capillary inner diameter (ID) and outer diameter (OD) and ID of the cone play important roles in a spray. The best explored dimensions for the silica capillary are 150–200 μm OD and 40–75 μm ID and 350 μm ID for the cone. These physical dimensions provide the best ionization efficiency and spectra of large proteins such as albumin can be obtained. The spectra of the samples can also be collected in water without adding any acid into the solution.

Choi, Jong Seob; Bae, Sunwoong; Kim, Kyung Hoon; Kim, Jaoon Y. H.; Sim, Sang Jun; Seo, Tae Seok

doi: 10.1039/c4ra09730kpmid: N/A

A perforated hemispherical microwell structure is shown to efficiently capture single Chlamydomonas reinhardtii (C. reinhardtii) cells, culture them to form colonies, and retrieve these colonies to serve as seeds for large-scale cultivation. This solution-phase formation and recovery of colonies could overcome the tedious and time-consuming process of selecting colonies from a solid-phase agar plate. The fabricated microdevice was composed of three layers: a top layer consisting of a cell solution for injection and recovery of a microalgal solution, a hemispherical perforated microwell array in the middle, and a bottom layer in which the solution is manipulated by controlling the hydrodynamic force. The microalgal (wild type and hygromycin B-resistant mutant) cells loaded in the top layer rapidly diffused into the microwell holes, and individual such cells were captured with high efficiency (>90%) and within 1 min by applying a withdraw mode in the bottom layer. Single-cell-based cultivation in a medium containing hygromycin B was then performed to generate colonies in the hemispherical microwell. While the wild type cells died, mutant cells resistant to hygromycin B survived well and grew into a colony within 2 days. The produced colonies in the microwells were recovered by applying a release mode in the bottom layer, so that a hydrodynamic force was exerted vertically to push out the colonies through the outlet in 10 s. The recovered cells were cultured on a large scale in medium by using a flask. The recovered C. reinhardtii was confirmed as a hygromycin B-resistant mutant by identifying the hygromycin gene in the polymerase chain reaction (PCR). The microdevice described here could in solution perform single-cell capture, colony formation, and retrieval of colonies for further large-scale cultivation, which could replace tedious and time-consuming solid-phase agar plate processes with a 7-fold reduction in the duration of the process.

Tricot, F.; Vocanson, F.; Chaussy, D.; Beneventi, D.; Reynaud, S.; Lefkir, Y.; Destouches, N.

doi: 10.1039/c4ra08804bpmid: N/A

TiO2:Ag nanocomposite thin films were prepared on plastic PET substrate in two steps. First, a sol–gel route and evaporation induced self-assembly (EISA) method were used to fabricate the TiO2 matrix. The use of thermal treatment being discordant with the plastic substrate, the mesoporosity was realized by chemical extraction or infrared annealing. Silver was then introduced in the film porosity in the form of ions by soaking the films into a silver salt. A reversible photochromic behavior was successfully demonstrated after successive cycles of UV and visible laser exposures without degrading the PET substrate. This laser-induced colour changes are based on the reversible growth and dissociation of silver nanoparticles within the titania matrix.

Qiu, Dan; Gu, Ling; Sun, Xiao-Li; Ren, Dong-Hong; Gu, Zhi-Guo; Li, Zaijun

doi: 10.1039/c4ra10774hpmid: N/A

We report here an effective synthetic route to gold coated spin-crossover core–shell nanocomposites (SCO@SiO2@Au) in which [Fe(Htrz)2(trz)](BF4)@SiO2 (SCO@SiO2) served as a support to the Au nanoparticles. The obtained core–shell nanocomposites were studied using numerous characterization techniques to define the structure, morphology, composition and especially the spin-crossover properties. The transmission electron micrographs illustrated that Au nanoparticles with an average diameter around 2.5 nm were decorated uniformly on the surface of SCO@SiO2. X-ray photoelectron spectroscopy measurements further confirmed the successful incorporation of gold nanoparticles on spin-crossover core. The Raman spectrum indicated that the plasmonic Au nanoparticles caused an efficient photo-thermal heating in the SCO@SiO2@Au nanocomposites, leading to a ∼100 times reduction of laser energy needed for spin state switching compared with SCO@SiO2. The magnetic study demonstrated that the embedded Au nanoparticles not only influenced the spin transition temperatures but also changed the widths of hysteresis loops. SCO@SiO2@Au nanocomposites may be applied to various areas where the fascinating spin-crossover core and the functional gold shell can be beneficial.