Sydnone Photochemistry: Formation of Nitrenes.

Photolysis of 3-phenyl- and 3-(3-pyridyl)-sydnones in Ar matrices is known to furnish Earl's bicyclic lactone (bicyclo[2.1.0]oxadiazolone) followed by the elimination of CO and the formation of carbodiimides .

Domino-like turn-on chemiluminescence amplification: Opening a gateway through proximal-imidazole species formation and metal-ligand complexation.

Due to their extremely low background signal and high sensitivity, the chemiluminescence (CL) probes have received a great attention in various chemical and biological applications. However, the lack of selectivity is still a challenging task. As an innovative topic of research, in this work we developed a domino-like turn-on CL reaction through proximal-imidazole species for the first time.

Nitrile Imine Cyclizations and Rearrangements: -Phenyl--styrylnitrile Imine and -Phenyl--phenylethynylnitrile Imine.

The formation and rearrangements of nitrile imines are of ongoing synthetic and theoretical interest. In this paper, we report a computational investigation at the M06/6-311 + G(d,p) level of the formation and rearrangement of propargylic phenylstyrylnitrile imine from 2-phenyl-5-styryltetrazole by flash vacuum pyrolysis (FVP). Nitrile imine cyclizes to 3a-3-styrylindazole , which is also generated by H-shifts in the FVP of 3-styrylindazole .

Molecular modelling of fullerene C functionalized by nitric oxide for use in biological environment.

The unique potential of fullerene C for various biological applications has ignited significant interest. However, its inherent non-polarity poses a critical challenge for its effective integration within biological systems. This study delves into the intricate physicochemical characteristics of the innovative [C + NO] complex using density functional theory and time-dependent density functional theory.

Retraction: Experimental and theoretical studies of the nanostructured {FeO@SiO@(CH)Im}C(CN) catalyst for 2-amino-3-cyanopyridine preparation an anomeric based oxidation.

[This retracts the article DOI: 10.1039/C6RA12299J.].

Azulene-Naphthalene, Naphthalene-Naphthalene, and Azulene-Azulene Rearrangements.

The mechanism(s) of thermal rearrangement of azulenes have been enigmatic for several decades. Herein, we have employed density functional theory (DFT) calculations at the M06-2X/6-311+G(d,p) level together with single-point calculations at the CCSD(T) level to assess possible mechanisms of the experimentally observed azulene and naphthalene automerizations. Of the two mechanisms proposed for naphthalene automerization, it is found that the benzofulvene (BF) route is favored over the naphthvalene mechanism by ∼6 kcal/mol and is energetically lower than the norcaradiene-vinylidene mechanism (NVM) for the azulene-naphthalene rearrangement ( ∼ 76.

Thermal Rearrangement of Azulenes to Naphthalenes: A Deeper Insight into the Mechanisms.

The thermal rearrangement of azulene to naphthalene has been the subject of several experimental and computational studies. Here, we reexamine the proposed mechanisms at the DFT level. The use of different functionals showed that the HF-exchange contribution significantly affects reaction energies and barrier heights.

When a "Dimroth Rearrangement" Is Not a Dimroth Rearrangement.

In the Dimroth rearrangement of heterocycles, often pyrimidines, an exocyclic and a ring substituent are interchanged. However, the term Dimroth rearrangement is frequently used even when there is no knowledge of the reaction mechanism and alternatives are likely. Here, we have employed density functional theory (DFT) calculations at the M06-2X/6-311+G(d,p) level to determine the most plausible rearrangement pathways of 3-aminothiocarbonylquinazoline , tetrahydrofuranylpyrimidine , and 5-allyltriazocine .

Recovered fluorescence of the Cd-nanocluster-Hg(II) system based on experimental results and computational methods.

Human Serum Albumin, a plasma protein existing in abundance, was selected as a template and reducing agent for the formation of CdNCs due to two factors: its stability and low cost. In the presence of human serum albumin (HSA), a selective and sensitive, low-cost, environmental friendly, and label-free off-on fluorescent sensor was synthesized and characterized for a bioaccumulating and toxic heavy metal, Hg and biothiols. HSA - CdNCs can specifically recognize Hg through aggregating NCs and causing fluorescence quenching.

Mechanism-Based Inactivation of Cytochrome P450 Enzymes: Computational Insights.

Mechanism-based inactivation (MBI) refers to the metabolic bioactivation of a xenobiotic by cytochrome P450s to a highly reactive intermediate which subsequently binds to the enzyme and leads to the quasi-irreversible or irreversible inhibition. Xenobiotics, mainly drugs with specific functional units, are the major sources of MBI. Two possible consequences of MBI by medicinal compounds are drug-drug interaction and severe toxicity that are observed and highlighted by clinical experiments.

Catalytic application of sulfamic acid-functionalized magnetic FeO nanoparticles (SA-MNPs) for protection of aromatic carbonyl compounds and alcohols: experimental and theoretical studies.

Protection techniques of functional groups within the structure of organic compounds are important synthetic methods against unwanted attacks from various reagents during synthetic sequences. Acetal and thioacetal groups are well known as protective functional groups in organic reactions. In this study, acetalization of carbonyl compounds with diols and dithiols and methoxymethylation of alcohols with formaldehyde dimethyl acetal (FDMA) have been carried out using sulfamic acid-functionalized magnetic FeO nanoparticles (SA-MNPs) as a heterogeneous solid acid catalyst.

Fabrication of Template-Less Self-Propelled Micromotors Based on A Metal-Sandwiched Polytryptophan Body: An Experimental and DFT Study.

The diverse capabilities of self-propelled micro/nanomotors open up significant opportunities for various environmental and biomedical applications. Here, a synchronized two-lobed bubble exhaust drives micromotor comprising a metal (cobalt and gold) sandwiched polytryptophan body (Au/poly-Trp/Co) in a non-curved direction. The autonomous motion is achieved through the decomposition of chemical fuel to result in a kayak-like system.

Structural Assessment of Hydrogen Bonds on Methylpentynol-Azide Clusters To Achieve Regiochemical Outcome of 1,3-Dipolar Cycloaddition Reactions Using Density Functional Theory.

This study was focused on the geometries and properties of the structural isomers obtained from a random walk of methylpentynol-HN clusters. The theoretical aspects of hydrogen bonding effects on the discussed 1,3-dipolar cycloaddition (1,3-DC) reactions [between methylpentynol () as a dipolarophile and azide () as a 1,3-dipole] have shown regioselective output concepts. The dipolarophile methylpentynol () was applied for the treatment of insomnia.

Ionically Tagged Magnetic Nanoparticles with Urea Linkers: Application for Preparation of 2-Aryl-quinoline-4-carboxylic Acids via an Anomeric-Based Oxidation Mechanism.

In this exploration, we reported the design and synthesis of a novel ionically tagged magnetic nanoparticles bearing urea linkers, namely, FeO@SiO@(CH)-urea-thiazole sulfonic acid chloride. The structure of the mentioned compound was fully characterized by using several techniques including Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, elemental mapping analysis, thermogravimetric analysis/differential thermal analysis, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometer. In the presence of the novel reusable catalyst, applied starting materials including aryl aldehydes, pyruvic acid, and 1-naphthylamine condensed to afford the desired 2-aryl-quinoline-4-carboxylic acid derivatives via an anomeric-based oxidation pathway under solvent-free conditions.

Electrochemical sensing of 2-methyl-4, 6-dinitrophenol by nanomagnetic core shell linked to carbon nanotube modified glassy carbon electrode.

Electrochemical behavior and sensing of 2-methyl-4, 6-dinitrophenol as an herbicide has been investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). We have synthesized a cefazolin (CEF) immobilized nanomagnetic core-shell (FeO@SiO-(CH)-CEF) and attached it on the modified glassy carbon electrode (GCE/MWCNT) through electrostatic adsorption (GCE/MWCNT/CEF-SiO@FeO). 2-Methyl-4, 6-dinitrophenol has an oxidation peak that is related to the formation of nitrosamine from hydroxylamine species.

Sub-femtomolar detection of HIV-1 gene using DNA immobilized on composite platform reinforced by a conductive polymer sandwiched between two nanostructured layers: A solid signal-amplification strategy.

This study introduces a signal amplification strategy rely on incorporating a specific polymer film between two typical nanostructured layers, aiming to improve the electrical properties of the platform to be able to transduce small binding event through sub-femtomolar detection of HIV-1 gene at the surface of the constructed biosensing device. The proposed composite was arrayed based on a conductive layer consist of p-aminobenzoic acid (PABA) sandwiched between the electrochemically reduced graphene oxide (ERGO) as the sub-layer, and the gold nanoparticles (AuNPs) as the interfacial layer. We computationally explored that how the use of such design enables the platform to transduce small changes in the interfacial properties of the biosensor, caused by low concentrations of HIV-1 gene, without needing any amplification strategy.

Determination of Hg and Cu ions by dual-emissive Ag/Au nanocluster/carbon dots nanohybrids: Switching the selectivity by pH adjustment.

An innovative dual-emissive ratiometric nanohybrid probe comprised of red-emitting a (Ag/Au)@insulin nanoclusters (NCs) and blue-emitting carbon dots (CDs) was designed for sensitive and selective ratiometric determination of Hg and Cu ions.The fluorescence intensity of CDs (λ = 340 nm; λ = 420 nm) was unaffected in the presence of the metal ions tested, whereas the red emitting NCs (λ = 340 nm; λ = 640 nm) was strongly quenched by both Cu and Hg ions. Interestingly, the selectivity of the probe toward these two ions was simply switched by controlling the pH of probe solution without using any chelating agent.

Transduction of interaction between trace tryptophan and surface-confined chromium salen using impedance spectroscopy. A sensing device that works based on highly selective inhibition of mediator's Faradaic process.

It is known that tryptophan (Trp) tends to be electropolymerized over a potential window that is mostly applied for voltammetric determination of Trp. Furthermore, over the applied potential range, most of Trp-sensors suffer from some possible interferences. Knowing these challenges motivated us to establish a novel sensing device able to monitor Trp before approaching the mentioned potential range, decreasing memory-effects and some sources of non-linearity during electrochemical measurements.

Resolving the Multiple Emission Centers in Carbon Dots: From Fluorophore Molecular States to Aromatic Domain States and Carbon-Core States.

Despite many efforts focused on the emission origin of carbon dots (CDs), it is still a topic of debate. This is mainly due to the complex structure of these nanomaterials. Here, we developed an innovative method to evaluate the number and spectral characterizations of various emission centers in CDs.

Experimental and Computational Evidence on the Interaction of Cycloalkyl α-Aminobisphosphonates with Calf Thymus DNA.

Fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, circular dichroism spectroscopy, viscometry, cyclic voltammetry, and differential pulse voltammetry were applied to investigate the competitive interaction of DNA with the three new cycloalkyl α-aminobisphosphonates (D-D) and spectroscopic probe, neutral red dye, and Hoechst (HO), in a Tris-hydrogen chloride buffer (pH 7.4). The spectroscopic and voltammetric studies showed that the groove binding mode of interaction is predominant in the solution containing DNA and α-aminobisphosphonates.

DFT and TD-DFT theoretical studies on photo-induced electron transfer process on [Cefamandole].C60 nano-complex.

The C fullerene displays a considerable electronegativity. It has a unique photophysical and electrochemical behavior that can be used as a suitable drug carrier. In the present study, the interaction of C fullerene as an electron recipient with the Cefamandole antibiotic was investigated in both ground and excited states using DFT and TD-DFT methods.

Introduction of a carbon paste electrode based on nickel carbide for investigation of interaction between warfarin and vitamin K1.

In this paper a novel electrochemical sensor based on nickel carbide (NiC) nanoparticles as a new modifier was constructed. NiC nanoparticle was synthesized and characterized by scanning electron microscopy, X-ray diffraction and first-principles study. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies confirmed the electrode modification.

Hydrophobic amino acids grafted onto chitosan: a novel amphiphilic chitosan nanocarrier for hydrophobic drugs.

Objective: The objective of this study is to develop a novel biocompatible amphiphilic drug delivery for hydrophobic drugs, chitosan (CS) was grafted to a series of hydrophobic amino acids including l-alanine (A), l-proline (P), and l-tryptophan (W) by carbodiimide mediated coupling reaction.

Materials And Methods: Chemical characteristics of the modified polymers were determined and confirmed by FT-IR, H NMR, and UV-vis spectroscopy and the degree of substitution was quantified by elemental analysis. The modified polymers were used to form amphiphilic chitosan nanocarriers (ACNs) by the conventional self-assembly method using ultrasound technique.

The simulation of UV spectroscopy and electronic analysis of temozolomide and dacarbazine chemical decomposition to their metabolites.

The electronic features of anti-tumor agent, temozolomide, and its degradation products (MTIC and metabolite AIC) have been traced by means of UV absorption spectroscopy in vacuo and aqueous media. For comparison, electronic spectra of related structures and drugs (e.g.

Interrupting the flux of delocalized electrons on a dibenzo-18-crown-6-embedded graphite sheet and its relative counteraction in the presence of potassium ions.

Delocalized electrons are free to move throughout a graphite sheet. Based on the interruption of this flux, a new strategy has been developed to establish a highly sensitive impedimetric sensing device for K(+) ions. Here, we report on the successful application of a simple graphite paste incorporated into dibenzo-18-crown-6 (DB18C6), which effectively impedes the electron flux on the graphite sheet.