Exploring the Correlation between Azido-Tetrazolo Tautomerizations and Isomer Structures: Electron Density of Bonding N Atoms and N-N Bond Polarity.

Azido-tetrazolo tautomerizations between azido N-heteroaromatic compounds and tetrazole-fused energetic materials can produce a new generation of high-energy density compounds. Density functional theory (DFT) computations are performed to explore the relationship between reaction barriers and electron densities of bonding N atoms, i.e.

Exploring the thermal decomposition and detonation mechanisms of 2,4-dinitroanisole by TG-FTIR-MS and molecular simulations.

2,4-dinitroanisole (DNAN), an insensitive explosive, has replaced trinitrotoluene (TNT) in many melt-cast explosives to improve the safety of ammunition and becomes a promising material to desensitize novel explosives of high sensitivity. Here, we combine thermogravimetric-Fourier transform infrared spectrometry-Mass spectrometry (TG-FTIR-MS), density functional theory (DFT), and ReaxFF molecular dynamics (MD) to investigate its thermal decomposition and detonation mechanisms. As revealed by TG-FTIR-MS, the thermal decomposition of DNAN starts at 453 K when highly active NO is produced and quickly converted to NO resulting in the formation of a large amount of Ph(OH)(OH)OCH.

How are -methylcarbamates encapsulated by β-cyclodextrin: insight into the binding mechanism.

Guest molecules containing chromophore groups encapsulated by β-cyclodextrin (β-CD) generate circular dichroism (CD) signals, which enables a preliminary prediction of their binding modes. However, the accurate determination of the representative binding conformation (RC) remains a challenging task due to the complex conformational space of these host-guest systems. Here, we combine a molecular dynamics/quantum mechanics/continuum solvent model (MD/QM/CSM) with induced circular dichroism (ICD) data (N.

A single-wavelength excited NIR fluorescence probe for distinguishing GSH/HS and Cys/Hcy in living cells and zebrafish through separated dual-channels.

Biothiols and hydrogen sulfide, as critical sulfur-containing reactive substances, serve essential functions in various human pathological processes, making it challenging to simultaneously distinguish them due to their similar reactivity and structures (-SH). Here, we rationalized the development of a single-wavelength excitation near-infrared (NIR) fluorescence probe, FC-NBD, for distinguishing GSH/HS and Cys/Hcy by separated fluorescence dual channels. In this probe, FC-NBD, composed of coumarin-benzopyrylium derivatives linked with nitro benzoxadiazole (NBD) via ether bonds, could quantitatively and selectively distinguish GSH/HS and Cys/Hcy with a low limit of detection (LOD) of 0.

Evaluating the impact of Hartree-Fock exact exchange on the performance of global hybrid functionals for the vertical excited-state energies of fused-ring electron acceptors using TD-DFT.

The acceptor-donor-acceptor structured fused-ring electron acceptors (FREAs) have piqued interest for organic solar cells. We herein employ time-dependent density functional theory to evaluate the effect of Hartree-Fock exact exchange (HFX) on the performance of 16 global hybrid functionals for computing the maximum absorption wavelengths () and the vertical excitation energies () of 34 molecules. We customize the HFX ratio in the functionals used to perform an in-depth analysis of its impact on the values.

Synthesis, in Vitro Cholinesterase Inhibition, Molecular Docking, DFT, and ADME Studies of Novel 1,3,4-Oxadiazole-2-Thiol Derivatives.

A series of 1,3,4-oxadiazole-2-thiol derivatives bearing various alkyl or aryl moieties were designed, synthesized, and characterized using modern spectroscopic methods to yield 17 compounds (6a-6q) that were screened for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes in the search for 'lead' compounds for Alzheimer's disease treatment (AD). The compounds 6q, 6p, 6k, 6o, and 6l showed inhibitory capability against AChE and BChE, with IC values ranging from 11.73±0.

Enhanced mechanical properties and biocompatibility on BC/HAp composite through calcium gluconate fortified bacterial.

Bacterial cellulose/hydroxyapatite (BC/HAp) composite is an outstanding candidate for bone tissue engineering. The conventional biomimetic mineralization method takes a long time with unsatisfactory mechanical properties and biocompatibility. Herein, we modified the BC by changing the carbon source to calcium gluconate during the biosynthesis process of BC by bacteria, providing nucleation sites for further mineralization in simulated body fluid.

Tandem CuAAC/Ring Cleavage/[4 + 2] Annulation Reaction to Synthesize Dihydrooxazines and Conversion to 2-Aminopyrimidines.

A tandem CuAAC/ring cleavage/[4 + 2] annulation reaction of terminal ynones, sulfonyl azides, and oximes has been developed to synthesize functionalized dihydrooxazines under mild conditions. In particular, intermediate -sulfonyl acylketenimines are the first example of a 4π-system participating in [4 + 2] cycloadditions, and dihydrooxazines can convert to 2-aminopyridines through ring cleavage under basic conditions.

Evaluating the nature of the vertical excited states of fused-ring electron acceptors using TD-DFT and density-based charge transfer.

Acceptor-donor-acceptor structured fused-ring electron acceptors (FREAs) are the most efficient electron acceptors used in organic solar cells. We use density functional theory (DFT), its time-dependent version (TD-DFT), and an intra-molecular charge transfer index to evaluate the nature of the excited states of FREAs. Typically, several efficient electronic transitions contribute to the absorption spectra of FREAs.

Oxygen vacancy mediated single unit cell BiWO by Ti doping for ameliorated photocatalytic performance.

Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host BiWO crystal lattice via varying content of Ti dopant to fabricate single-unit-cell layered structure, resulting in enhanced visible-light-driven photocatalytic efficiency.

TD-DFT benchmark for UV-visible spectra of fused-ring electron acceptors using global and range-separated hybrids.

Non-fullerene acceptors, especially acceptor-donor-acceptor structured fused-ring electron acceptors (FREAs), have attracted widespread attention in organic solar cells because of their versatile molecular design in fine-tuning light absorption and energy levels. We report the accuracy of Time-Dependent Density Functional Theory (TD-DFT) for FREAs by comparing their theoretically predicted vertical absorption wavelength (λver-abso) with the experimental maximum absorption (λmax). The λver-abso values of 50 molecules obtained from major types of FREAs have been investigated using TD-DFT by considering the solvent effects.

Organocatalyzed Solvent Free and Efficient Synthesis of 2,4,5-Trisubstituted Imidazoles as Potential Acetylcholinesterase Inhibitors for Alzheimer's Disease.

The catalytic potential of pyridine-2-carboxlic acid has been evaluated for efficient, green and solvent free synthesis of 2,4,5-trisubstituted imidazole derivatives 3a-3m. The compounds 3a-3m were synthesized by one pot condensation reaction of substituted aromatic aldehydes, benzil, and ammonium acetate in good to excellent yields (74-96 %). To explore the potential of these compounds against Alzheimer's disease, their inhibitory activities against acetylcholinesterase (AChE) were evaluated.

A combined experimental and DFT mechanistic study for the unexpected nitrosolysis of -hydroxymethyldialkylamines in fuming nitric acid.

The reaction of dimorpholinomethane in fuming HNO was investigated. Interestingly, the major product was identified as -nitrosomorpholine and a key intermediate -hydroxymethylmorpholine was detected during the reaction by H-NMR tracking which indicates that the reaction proceeds an unexpected nitrosolysis process. A plausible nitrosolysis mechanism for -hydroxymethyldialkylamine in fuming nitric acid involving a HNO redox reaction is proposed, which is supported by both experimental results and density functional theory (DFT) calculations.

Metal-to-Ligand Charge-Transfer-based Visual Detection of Alkaline Phosphatase Activity.

The ability to directly detect alkaline phosphatase (ALP) activity in undiluted serum samples is of great importance for clinical diagnosis. In this work, we report the use of the distinctive metal-to-ligand charge-transfer (MLCT) absorption properties of the Cu(BCA) (BCA = bicinchoninic acid) reporter for the visual detection of ALP activity. In the presence of ALP, the substrate ascorbic acid 2-phosphate (AAP) can be enzymatically hydrolyzed to release ascorbic acid (AA), which in turn reduces Cu to Cu.

Synthesis and evaluation of a novel 'off-on' chemical sensor based on rhodamine B and the 2,5-pyrrolidinedione moiety for selective discrimination of glutathione and its bioimaging in living cells.

A new "turn-on" fluorescent probe, RDMBM, based on the rhodamine B dye and the 2,5-pyrrolidinedione moiety was synthesized and characterized. Its sensing behavior toward various amino acids was evaluated via UV-vis and fluorescence spectroscopic techniques. The observed spectral changes showed that RDMBM displays high selectivity and sensitivity toward GSH in MeOH/HO (1:2, v/v, pH 7.

Fluorescence quenching based alkaline phosphatase activity detection.

Simple and fast detection of alkaline phosphatase (ALP) activity is of great importance for diagnostic and analytical applications. In this work, we report a turn-off approach for the real-time detection of ALP activity on the basis of the charge transfer induced fluorescence quenching of the Cu(BCDS) (BCDS = bathocuproine disulfonate) probe. Initially, ALP can enzymatically hydrolyze the substrate ascorbic acid 2-phosphate to release ascorbic acid (AA).

Organocatalyzed and mechanochemical solvent-free synthesis of novel and functionalized bis-biphenyl substituted thiazolidinones as potent tyrosinase inhibitors: SAR and molecular modeling studies.

Eluding the involvement of solvents in organic synthesis and introducing environment friendly procedures can control environmental problems. A facile and an efficient solvent free mechanochemical method (grinding) is achieved to synthesize novel bis-biphenyl substituted thiazolidinones using non-toxic and cheap N-acetyl glycine (NAG). Organocatalytic condensation of a series of Schiff's bases bearing different substituents with thioglycolic acid produces a variety of thiazolidinones derivatives in good to excellent yield.

Facile colorimetric assay of alkaline phosphatase activity using Fe(II)-phenanthroline reporter.

We report a versatile approach for the colorimetric assay of alkaline phosphatase (ALP) activity based on the distinctive metal-to-ligand charge-transfer (MLCT) absorption properties of Fe(II)-phenanthroline reporter. In the presence of ALP, the applied substrate ascorbic acid 2-phosphate is enzymatically hydrolyzed to produce ascorbic acid, which then reduces Fe to Fe. The complexation of Fe with the bathophenanthroline disulfonate (BPS) ligand generates a blood-red Fe(BPS) reporter, which is characterized by an intense MLCT absorption band at 535 nm in the visible range.

Turn-On Colorimetric Platform for Dual Activity Detection of Acid and Alkaline Phosphatase in Human Whole Blood.

The activity detection of acid phosphatase (ACP) and alkaline phosphatase (ALP) is of great importance to the diagnosis and prognosis of related diseases. In this work, we report for the first time a turn-on colorimetric platform for the activity detection of ACP and ALP, by exploiting Cu(BCDS) (BCDS=bathocuproinedisulfonate) as the probe. The presence of ACP or ALP dephosphorylates the substrate ascorbic acid 2-phosphate to produce ascorbic acid, which then reduces Cu(BCDS) into Cu(BCDS) , leading to a turn-on spectral absorption at 484 nm and a dramatic color change of the solution from colorless to orange-red.

Dual pH-Mediated Mechanized Hollow Zirconia Nanospheres.

We demonstrate for the first time how to assemble mechanized hollow zirconia nanospheres (MHzNs), consisting of hollow mesoporous zirconia nanospheres (HMZNs) as nanoscaffolds and supramolecular switches anchored on the exterior surface of HMZNs. The remarkable advantage of substitution of HMZNs for conventional mesoporous silica nanoscaffolds is that HMZNs can suffer the hot alkaline reaction environment, which provides a novel strategy for functionalization and thus achieve dual pH-mediated controlled release functions by simple and practicable assembly procedure. Under neutral solution, cucurbituril[7] (CB[7]) macrocycles complexed with propanone bis(2-aminoethyl)ketal (PBAEK) to form [2]pseudorotaxanes as supramolecular switches, blocking the pore orifices and preventing the undesirable leakage of cargoes.

Side-chain Engineering of Benzo[1,2-b:4,5-b']dithiophene Core-structured Small Molecules for High-Performance Organic Solar Cells.

Three novel small molecules have been developed by side-chain engineering on benzo[1,2-b:4,5-b']dithiophene (BDT) core. The typical acceptor-donor-acceptor (A-D-A) structure is adopted with 4,8-functionalized BDT moieties as core, dioctylterthiophene as π bridge and 3-ethylrhodanine as electron-withdrawing end group. Side-chain engineering on BDT core exhibits small but measurable effect on the optoelectronic properties of small molecules.

Visible-light-initiated difluoromethylation of arene diazonium tetrafluoroborates.

A mild and efficient method for the radical addition of α-aryl-β,β-difluoroenol silyl with arene diazonium tetrafluoroborates at room temperature has been disclosed, which involves an innate radical long chain cycle, so only a small amount (0.05 mol%) of photocatalyst and a short light exposure time are required as radical initiators. A proposed mechanism for the transformation is also illustrated based on the results of control experiments and quantum calculations.

Selenium-substituted polymers for improved photovoltaic performance.

Four isostructural donor-acceptor alternating polymers of benzodithiophene (BDT)/naphthodifuran (NDF) and benzoselenadiazole (BSe)/benzothiadiazole (BT) have been developed and evaluated for organic photovoltaics. The substitution of one-atom (Se for S) in the accepting units exerts remarkable impact on the optoelectronic properties of polymers. Extended absorption, narrowed bandgap and higher HOMO energy levels were observed for Se-containing polymers in comparison to their S-containing counterparts.

Voltage/pH-Driven Mechanized Silica Nanoparticles for the Multimodal Controlled Release of Drugs.

The major challenges of current drug delivery systems for combination chemotherapy focus on how to efficiently transport drugs to target sites and release multiple drugs in a programmed manner. Herein, we report a novel multidrug delivery system, MSNPs 1, based on mechanized silica nanoparticles, which were constructed through functionalization of mesoporous silica nanoparticles with the acid-cleavable intermediate linkages and the monoferrocene functionalized β-cyclodextrin (Fc-β-CD) as supramolecular nanovalves. MSNPs 1 achieved zero premature release in the physiological pH solution and realized two different release modalities.

Engineering Cyclodextrin Clicked Chiral Stationary Phase for High-Efficiency Enantiomer Separation.

The separation of racemic molecules is of crucial significance not only for fundamental research but also for technical application. Enantiomers remain challenging to be separated owing to their identical physical and chemical properties in achiral environments. Chromatographic techniques employing chiral stationary phases (CSPs) have been developed as powerful tools for the chiral analysis and preparation of pure enantiomers, most of which are of biological and pharmaceutical interests.