Continuum interpretation of virial stress in molecular simulations

The equivalence of the virial stress and Cauchy stress is reviewed using both theoretical arguments and numerical simulations. Using thermoelasticity problems as examples, we numerically demonstrate that virial stress is equivalent to the continuum Cauchy stress. Neglecting the velocity terms in the definition of virial stress as many authors have recently suggested, can cause significant errors in interpreting MD simulation results at elevated temperatures (T > 0 K).     

Tilianin: A Potential Natural Lead Molecule for New Drug Design and Development for the Treatment of Cardiovascular Disorders

Cardiovascular disorders (CVDs) are the leading risk factor for death worldwide, and research into the processes and treatment regimens has received a lot of attention. Tilianin is a flavonoid glycoside that can be found in a wide range of medicinal plants and is most commonly obtained from Dracocephalum moldavica. Due to its extensive range of biological actions, it has become a well-known molecule in recent years. In particular, numerous studies have shown that tilianin has cardioprotective properties against CVDs. Hence, this review summarises tilianin’s preclinical research in CVDs, as well as its mechanism of action and opportunities in future drug development. The physicochemical and drug-likeness properties, as well as the toxicity profile, were also highlighted. Tilianin can be a natural lead molecule in the therapy of CVDs such as coronary heart disease, angina pectoris, hypertension, and myocardial ischemia, according to scientific evidence. Free radical scavenging, inflammation control, mitochondrial function regulation, and related signalling pathways are all thought to play a role in tilianin’s cardioprotective actions. Finally, we discuss tilianin-derived compounds, as well as the limitations and opportunities of using tilianin as a lead molecule in drug development for CVDs. Overall, the scientific evidence presented in this review supports that tilianin and its derivatives could be used as a lead molecule in CVD drug development initiatives.     

Schiff’s base phenol-hydrazone derivatives as colorimetric chemosensors for fluoride ions

Two new chromogenic receptors 4-nitro-2-[(phenylhydrazoimino)methyl]phenol (1) and 4-nitro-2-[(4-nitrophenylhydrazoimino)methyl]phenol (2) containing a nitro group as a signalling unit and OH and NH groups as binding sites have been synthesized and characterized by spectroscopic techniques and XRD. Both receptors show colorimetric responses and UV-vis spectral changes in the presence of fluoride ions in organic solvents.     

Synthesis and structural study of thiacyclophanes utilizing dibromides and methane dithiolate

The synthesis of a series of thiacyclophanes and optically active binaphthol-based chiral thiacyclophanes is reported with XRD structure. Two diastereomeric tetrathiacyclophanes are designed and synthesized. The two diastereomers are evidenced by crystal structure; the single-crystal X-ray studies reveal that one of the isomers possesses an inherent property of self-assembling into a vertical stack of tunnel-like structures.     

Nickel‐Catalyzed Borylative Coupling of Alkynes,Enones, and Bis(pinacolato)diboron as a Route to Substituted Alkenyl Boronates

Three‐component coupling reactions of an alkyne, an enone, and a diboron reagent provide access to highly substituted alkenyl boronates in good to excellent yields (see scheme). The coupling is highly regio‐ and stereoselective, and the products are amenable to further functional‐group transformations. R¹,R²=H, alkyl, aryl, CO₂Me; R³=alkyl, Ph; R⁴,R⁵=H, alkyl.

     

Quaternary ammonium hydroxide-functionalized g-C3N4 catalyst for aerobic hydroxylation of arylboronic acids to phenols

A new and efficient metal-free approach toward the synthesis of phenols via an aerobic hydroxylation of arylboronic acids by using a novel quaternary ammonium hydroxide g-C₃N₄ catalyst has been described. The functionalized quaternary ammonium hydroxide (g-C₃N₄-OH) has been prepared from graphitic carbon nitride (g-C₃N₄) scaffold by converting the residual –NH₂ and –NH groups to quaternary methyl ammonium iodide by performing a methylation reaction with methyl iodide followed by ion-exchange with 0.1 N KOH or anion exchange resin Amberlyst A26 (OH- form) by post-synthetic modification. The resultant g-C₃N₄-OH was characterized by XRD, FTIR, field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), N₂ adsorption/desorption isotherms, and acid–base titration. Tested as solid-base catalysts, the g-C₃N₄-OH showed excellent catalytic activity in the aerobic hydroxylation reaction by converting a variety of arylboronic acids to the corresponding phenols in high yields. More importantly, the g-C₃N₄-OH solid-base has been successfully reused four times with the minor loss of initial catalytic activity (10.5%).     

NLO characteristics of D-π-A coumarin-thiophene bridged azo dyes by Z-scan and DFT methods

ABSTRACT

The structural, electronic, intramolecular charge transfer (ICT) and nonlinear optical (NLO) properties of the donor-π-acceptor (D-π-A) azo linked dyes bearing coumarin thiophene bridge with different acceptors were inspected by Z-scan and DFT methods. The dye 3a exhibits bathochromic absorption maxima (649 and 650?nm) in the near IR region in DMF and DMSO. The dye 3a holds low HOMO–LUMO gap elucidated by CV and DFT indicating strong ICT character. The thermal stability is high for 3a and it shows enhanced NLO property by Z-scan and DFT methods as predicted in both global and range-separated hybrid functionals. The molecular geometry was optimised using B3LYP/6-311?+?g(d,p). The ICT characteristics are correlated with NLO properties obtained by Z-scan and DFT techniques.