Bis(phenylethynyl)arene Linkers in Tetracationic Bis-triarylborane Chromophores Control Fluorimetric and Raman Sensing of Various DNAs and RNAs

We report four new luminescent tetracationic bis-triarylborane DNA and RNA sensors that show high binding affinities, in several cases even in the nanomolar range. Three of the compounds contain substituted, highly emissive and structurally flexible bis(2,6-dimethylphenyl-4-ethynyl)arene linkers ( 3 : arene=5,5′-2,2′-bithiophene; 4 : arene=1,4-benzene; 5 : arene=9,10-anthracene) between the two boryl moieties and serve as efficient dual Raman and fluorescence chromophores. The shorter analogue 6 employs 9,10-anthracene as the linker and demonstrates the importance of an adequate linker length with a certain level of flexibility by exhibiting generally lower binding affinities than 3 – 5 . Pronounced aggregation–deaggregation processes are observed in fluorimetric titration experiments with DNA for compounds 3 and 5 . Molecular modelling of complexes of 5 with AT-DNA, suggest the minor groove as the dominant binding site for monomeric 5 , but demonstrate that dimers of 5 can also be accommodated. Strong SERS responses for 3 – 5 versus a very weak response for 6 , particularly the strong signals from anthracene itself observed for 5 but not for 6 , demonstrate the importance of triple bonds for strong Raman activity in molecules of this compound class. The energy of the characteristic stretching vibration of the C≡C bonds is significantly dependent on the aromatic moiety between the triple bonds. The insertion of aromatic moieties between two C≡C bonds thus offers an alternative design for dual Raman and fluorescence chromophores, applicable in multiplex biological Raman imaging.     

Effects of the composition of active carbon electrodes on the impedance performance of the AC/AC supercapacitors

Journal of Solid State Electrochemistry - Considerable diversity in the preparation methodology of active electrode materials for carbon supercapacitors makes direct comparison of the results...     

Degradable Nanomotors Using Platinum Deposited Complex of Calcium Carbonate and Hyaluronate Nanogels for Targeted Drug Delivery

Recently, micro/nanomotor systems have been widely investigated for biomedical applications especially for the active transport and delivery of specific drugs. However, there are few stimuli-responsive micro/nanomotor systems to enhance the drug delivery efficiency and reduce side effects by the spatiotemporal controllability. Here, a degradable nanomotor is first fabricated for targeted drug delivery using a platinum (Pt)-deposited complex of calcium carbonate and cuccurbit[6]uril-conjugated hyaluronate (Pt/CaCO₃@HA-CB[6]). The nanomotors could efficiently deliver model drugs to the cells in reactive oxygen species (ROS) abundant environments such as the tumor site. After reaching the tumor site around pH 6.5, Pt/CaCO₃@HA-CB[6] nanomotors (≈1 µm) are pH-responsively disintegrated by the dissociation of CaCO₃ and the encapsulated HA-CB[6] (≈300 nm) are released for cancer cell uptake. The released HA conjugate are finally uptaken into cancer cells via HA receptor-mediated endocytosis. Moreover, model drugs are modularly loaded into the nanomotors via the host–guest chemistry of CB[6] for stable delivery to cancer cells. Taken together, Pt/CaCO₃@HA-CB[6] nanomotors systems could be successfully harnessed for active drug delivery to cancer cells.     

The Mechanism of Copper-Catalyzed Trifunctionalization of Terminal Allenes

A highly selective copper-catalyzed trifunctionalization of allenes has been established based on diborylation/cyanation with bis(pinacolato)diboron (B₂pin₂) and N-cyano-N-phenyl-p-toluenesulfonamide (NCTS). The Cu-catalyzed trifunctionalization of terminal allenes is composed of three catalytic reactions (first borocupration, electrophilic cyanation, and second borocupration) that provide a densely functionalized product with regio-, chemo- and diastereoselectivity. Allene substrates have multiple reaction-sites, and the selectivities are determined by the suitable interactions (e.g., electronic and steric demands) between the catalyst and substrates. We employed DFT calculations to understand the cascade copper-catalyzed trifunctionalization of terminal allenes, providing densely-functionalized organic molecules with outstanding regio-, chemo- and diastereoselectivity in high yields. The selectivity challenges presented by cumulated π-systems are addressed by systematic computational studies; these give insight to the catalytic multiple-functionalization strategies and explain the high selectivities that we see for these reactions.     

Nanoconfinement of the Low-Temperature Dark Conglomerate: Structural Control from Focal Conics to Helical Nanofilaments

The helical nanofilament (HNF) and low-temperature dark conglomerate (DC) liquid-crystal (LC) phases of bent-core molecules show the same local layer structure but present different bulk morphologies. The DC phase is characterized by the formation of nanoscale toric focal conics, whereas the HNF phase is constructed of bundles of twisted layers. Although the local layer structure is similar in both phases, materials that form these phases tend to form one morphology in preference to the other. Targeted control of the nanostructures would provide pathways to potential applications and insight into how conditions drive a specific phase formation. Here, W624, a compound known to form the DC phase is confined in nanometer scale channels of porous anodized aluminum oxide (AAO) membranes. Within each nanochannel, the DC phase is suppressed forming the HNF structure instead, indicating the nanoscale spatial limitation can control the phase structure of the DC phase.     

DNA binding and antitumor activities of zinc(II) complexes with some S-alkenyl derivatives of thiosalicylic acid

Transition Metal Chemistry - Two zinc(II) complexes with S-alkenyl derivatives of thiosalicylic acid as ligands have been synthesized and characterized by microanalysis, IR, 1H and 13C NMR...     

Novel quantized fuzzy adaptive design for nonlinear systems with sliding mode technique

Nonlinear Dynamics - This article examines the fuzzy adaptive design and the sliding mode control issue for a class of quantized systems subject to input nonlinearities. We establish a new...     

Radioactivity of building materials in Serbia and assessment of radiological hazard of gamma radiation and radon exhalation

Journal of Radioanalytical and Nuclear Chemistry - This paper presents a gamma spectrometric analysis of 47 samples of building materials produced and used in Serbia. Based on the measured activity...