Multiple-color aggregation-induced emission-based Schiff base sensors for ultrafast dual recognition of Hg2+ and pH integrating Boolean logic operations

Seven Schiff base fluorescent sensors (L¹?L⁷) with multiple-color aggregation-induced emission (AIE) properties for detection of Hg²⁺ ions and pH integrating Boolean logic operations were reported. With appropriate ligand-to-metal coordination (L?HgCl₂) and AIE characteristic, L?HgCl₂ can aggregate into nanoparticles, followed by activation of strong emission, therefore, the “turn-on” assay for detection of Hg²⁺ can be established. Sensing mechanism was calculated through single-crystal X-ray diffraction, Job’s Plot, Benesi?Hildebrand equation, dynamic light scattering, scanning electron microscopy, and elemental mapping analysis. Density functional theory calculations revealed that L?HgCl₂ can avoid one-electron transfer and retain bright luminescence compared with that of L. Different (highest unoccupied orbit) HOMO and (Lowest empty orbit) LUMO energy gaps enable the different electron transitions, resulting in the multiple-color fluorescence properties. Especially, L¹?L⁷ exhibit pH-dependent fluorescent characteristics: different electron-donating ability of the substituent groups for L¹?L⁷ show different titration jump of pH. Advanced level molecular logic gates have been constructed integrating the sensing of Hg²⁺ and pH. More importantly, the L-coated test paper applied in Hg²⁺ sensing makes tracing possible, which is convenient for confidential purposes.     

Spirobifluorene Metallaaromatics

Spirobifluorene derivatives find use in many end-user applications. Therefore, further expansion of their scope is the focus of many research studies. However, although the optical properties of spirobifluorenes can be greatly tuned through incorporation of metal complexes, to date, spirobifluorene metallaaromatics remain unknown. Taking advantage of the versatility of our methodology for the synthesis of metallaaromatic systems, this work reports the first metallaaromatic spirobifluorene compound. The presence of an Ir atom was found to redshift the absorption maximum by ca. 1.1 eV compared to bare spirobifluorene. Additionally, X-ray analysis as well as anisotropy of the current-induced density calculations revealed this compound to be of aromatic nature. The high stability in solution, solid state, under air, and at high temperature, as well as distinct optical properties of this new class of compounds are expected to open new frontiers for chiroptical and optoelectronic applications.     

Distinct Helical Molecular Orbitals through Conformational Lock**

Several theoretical studies have proposed strategies to generate helical molecular orbitals (Hel-MOs) in [n]cumulenes and oligoynes. While chiral even-[n] cumulenes feature Hel-MOs, odd-[n] cumulenes may also present them if the terminal groups lie in different planes. However, the proposed systems have been either experimentally unfeasible or resulted in opposite pseudo-degenerated Hel-MOs. We hereby demonstrate the introduction of a remarkable energy difference between helical orbitals of opposite twist by fixing the torsion angle between the terminal groups in butadiyne fragments. To experimentally lock the conformation of the terminal groups, we designed and synthesized cyclic architectures by combining acetylenes with chiral spirobifluorenes. The high stability of these systems with distinct helical orbitals allowed their isolation and full characterization. In our view, these results constitute a step further in the development of real systems presenting helical molecular orbitals.     

Optimal harvesting for periodic age-dependent population dynamics with logistic term

We prove an asymptotic behavior result for an age-dependent population dynamics with logistic term and periodic vital rates. We investigate next an optimal harvesting problem related to a periodic age-structured model with logistic term. Existence of an optimal control and necessary optimality conditions are established. A conceptual algorithm to approximate the optimal pair is derived and some numerical experiments are presented.     

On the spin assignment to the 268 keV state in Au197

It is shown that the recent internal conversion data favour theI=1/2 value if the penetration effects inM1 conversion are fully taken into account. The 191 keV transition is found to be anM1 +E0 mixture with 41 (2)%E0, although the measuredK conversion coefficient is smaller than the theoreticalβ _k(M1) value.     

An Unprecedented Synthesis of 3,3‐Disubstituted Isochroman‐1,4‐diones Using Nitrones as Oxygen Atom Donors

A one‐pot reaction of ninhydrin, N‐methyl‐C‐phenyl nitrone, and secondary amine leading to the unprecedented synthesis of 3,3‐disubstituted isochroman‐1,4‐diones is described here. In this reaction, nitrone acts as an oxygen atom donor producing an imine as a side product. The mild reaction conditions, the flexibility of the secondary amines that can be used, the novelty of the product, and the good yields are the highlights of this reaction.     

Reaction of dimethoxycarbene-DMAD zwitterion with 1,2-diones and anhydrides: a novel synthesis of highly substituted dihydrofurans and spirodihydrofurans

The zwitterion formed by the reaction of dimethoxycarbene and DMAD adds efficiently to one of the carbonyl groups of 1,2-dicarbonyl compounds and anhydrides to generate dihydrofurans and spirodihydrofurans in good yields. In many cases, the carbene inserts into the C-C bond of the dione to yield masked vicinal tricarbonyl systems.     

Zhurnal Neorganicheskoi Khimii (Inorganic Chemistry) is 50

Chronicle

Zhurnal Neorganicheskoi Khimii (Inorganic Chemistry) is 50     

Development of a microfluidic‐based assay on a novel nitrocellulose platform

A novel microfluidic paper‐based analytical device (μPAD) utilizing a nitrocellulose (NC) membrane to detect IgG antibodies through a colorimetric analysis is described. The μPAD was constructed using layered polyethylene terephthalate (PET) and pressure‐sensitive adhesives (PSA). The biotin labeled Goat Anti‐Mouse IgG antibody was spotted and dried on the NC channel prior to subjecting it to a series of wash solutions (Tris‐tween), increasing concentrations of alkaline phosphatase conjugated to streptavidin (Strep‐ALP), and para‐nitrophenyl phosphate (p‐NPP) realizing a vibrant yellow color. The reaction proceeds for 10 min before applying the p‐NPP stop solution. The device was then dried, scanned, and analyzed yielding a linear range of inverse yellow color intensities versus Strep‐ALP concentrations. The development of this simple μPAD should further facilitate the use of NC in colorimetric assays to detect and quantitate antibodies.