DNAzyme based electrochemical sensors for trace uranium

We have developed a uranyl-specific DNAzyme that was immobilized on the surface of a gold electrode to give a highly sensitive and selective biosensor for uranyl ion. The typical DNAzyme system consisted of the RNA (rA) as the substrate (ADNA), and the other strand is the enzyme (TDNA) with a ferrocene (Fc). The presence of uranyl ion induces the cleavage of the DNA substrate strand at the rA position to form two fragments. The Fc unit thereby is released from the surface of the electrode, and this results in a decreased peak current. This electrochemical biosensor has a dynamic range from 2 nM to 14 nM of uranyl ion, with a detection limit at 1 nM. It exhibits high sensitivity and excellent selectivity over other metal ions, and thus represents a promising technique for simple, fast, on-site, and real-time electrochemical sensing of UO₂(II) ion. It also serves as a guide in choosing different methods for designing electrochemical sensors for other metal ions.

Computational design and structure-property relationship studies on (I2GaN3) n (n = 1–4) clusters

To look for the single-source precursors, density functional theory calculations were performed to study structures, IR spectra, and stabilities of the possible isomers for the clusters (I₂GaN₃) _n (n = 1–4). It is found that the optimized (I₂GaN₃) _n (n = 2–4) clusters all possess cyclic structure containing Ga-N_α-Ga linkages, and azido group in azides has linear structure. Trends in geometrical parameters with the oligomerization degree n are discussed. The IR spectra are obtained and assigned by vibrational analysis. Thermodynamic properties are linearly correlated with the oligomerization degree n as well as the temperature. Mean-while, the oligomerizations can occur spontaneously at 298.2 K.     

Ferric(III) Nitrate Supported on Kieselguhr: A New Reagent for Selective Oxidation of Alcohols

A selective and effective oxidation of alcohols into the corresponding aldehydes and ketones, respectively, with a new reagent, ferric(III) nitrate supported on kieselguhr, under heterogeneous conditions is reported.     

Facile Synthesis of 5‐Benzylidene Rhodamine Derivatives under Microwave Irradiation

A series of 5‐benzylidenerhodamine derivatives were synthesized by the cross‐aldol condensation of an aromatic aldehyde with rhodamine or rhodamine acetic acid in sodium acetate/acetic acid under microwave irradiation. The reaction was completed in 8–20 min with 63–94% yields and was environmentally benign with easy workup.     

Self-assembly of 5,11,17,23-tetranitro-25,26,27,28-tetramethoxythiacalix[4]arene with neutral molecules and its use for anion recognition

Methylation of 5,11,17,23-tetranitrothiacalix[4]arene with diazomethane leads to the tetramethoxy derivative, which was studied using single-crystal X-ray crystallography. It revealed that this compound, albeit in the 1,3-alternate conformation, can form the inclusion complexes with various solvent molecules possessing acidic methyl groups (ethyl acetate, nitromethane, acetone, acetonitrile) and creates interesting infinite channels filled with solvent molecules. The subsequent transformation of nitro groups into the ureido moieties gave receptors capable of anion recognition even in a highly HB-competitive solvent like DMSO.     

Oxidation of Benzoins to Benzils with Chromium Trioxide Under Viscous Conditions

Reaction of chiral allylic cyclic carbonates with Grignards reagent in the presence of NiCl₂(dppe) as a catalyst afforded the alkylated (E)-allylic alcohols with high regio- and diastereoselectivity.     

A novel kind of dimmer (excimer)-induced-AIE compound 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one as high selective bisulfite anion probe

An interesting dimmer (excimer)-induced-AIE characteristic of 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one was observed. By using a ring-opening reaction, we developed a novel fluorescent probe based on sub-micron particles of 2-phenylisothiazolo[5,4-b]pyridin-3(2H)-one in water.     

Supramolecular organogelators based on Janus type AT nucleosides

J-AT nucleoside-based organogelators 1a and 1b were designed and synthesized. They were endowed with unparalleled superiority to natural nucleobase analogues 2–6 to gelate aromatic solvents due to their excellent self-assembly properties. The J-AT nucleoside-based organogelators showed a specific self-complementary base pair recognition characteristic. The gel stabilities of 1a and 1b were drastically influenced by adenine analogue 2, hardly affected by thymine analogue 3, uracil analogue 4, cytosine analogue 5, and mildly interrupted by guanine analogue 6.     

A new organic far-red mechanofluorochromic compound derived from cyano-substituted diarylethene

A new cyano-substituted diarylethene derivative (R-NH₂) with reversible far-red mechanofluorochromic property was synthesized and confirmed by standard spectroscopic methods. To the best of our knowledge, the 684 nm red-shifted wavelength of the ground R-NH₂ is the longest wavelength that has appeared in the literature. The mechanofluorochromic mechanism was investigated by small and wide-angle X-ray scattering and was ascribed to the destruction of crystalline structure. More in-depth study by infrared spectra and time-resolved emission-decay behaviors showed that the changes of C–H out-of-plane bending vibrations in aryl group of the compound and the obvious increase of fluorescence lifetime might be the fundamental reasons. The synthetic strategy reported here can be extended to prepare more and more long-wavelength emission mechanofluorochromic materials, which can broaden the scope of application of such materials and for thoroughly understanding the mechanofluorochromic mechanism.     

Macrocycles consisting of flexible and rigid segments: enforced folding and host-guest inclusion exciplex formation

Macrocycles consisting of two tris(phenylene ethynylene) (or tri-PE) units connected via two flexible linkers adopt an ‘unfolded’ conformation that is converted into a folded conformation upon introducing intramolecular hydrogen bonding interaction. These foldable macrocycles are capable of forming inclusion charge transfer (CT) complex with electron-deficient small aromatics.