In the present work, the quantum theoretical calculations of the molecular structure of the 2-aryl-1, 3, 4-oxadiazole derivatives (A-G) has been investigated and are evaluated using Density Functional Theory (DFT) in gas phase. The geometry of the title compounds was optimized by B3LYP method and 6-311+G** basis set. The theoretical 1H and 13C NMR chemical shift (GIAO method) values of the title compounds are calculated and compared with the experimental results. The computed data of the chemical shift are in good agreement with the experimental data. Frontier molecular orbitals (FMOs) such as HOMO orbital, LUMO orbital and HOMO-LUMO energy gap, molecular electrostatic potential (MEP), electronic properties such as ionization potential (I), electron affinity (A), global hardness, global hardness (h), electronegativity (c), electronic chemical potential (m), electrophilicity ( w) and chemical softness (S) of the title compounds were investigated discussed by theoretical calculations. The FMO analysis suggests that charge transfer is taking place within the molecules. The thermodynamic parameters of the compounds were calculated and it it was found that the compounds B and C are more stable than other molecules. Also the electronic structure of the compound B were studied by using Natural Bond Orbital (NBO) analysis in order to understand hyper conjugative interactions and charge delocalization.

Currently, carbon quantum dots have attracted considerable attention due to their unique properties and desirable advantages. High crystallinity, water solubility, good dispersibility, small size, low toxicity, inexpensive raw materials, high chemical stability, environmental compatibility, low cost, stability under light, desirable charge transfer with advanced electronic conductivity, as well as specific thermal and mechanical properties are some of these features. Carbon quantum dots have various applications in different fields. Fabrication of precise chemical and biological sensors, bioimaging, solar cells, drug tracking, nanomedicine, light-emitting diodes (LEDs), and electrocatalysts are some of these applications. Biological sensors based on carbon quantum dots are capable of detecting various metal ions, acids, proteins, biotin, polypeptides, DNA and miRNA, water pollutants, hematin, drugs, vitamins, and other chemicals. In the present study, the properties of carbon quantum dots and some of their fabrication and applications methods have been addressed. In continuation of the paper, the effect of carbon quantum dots on important factors in plants such as growth and development, photosynthesis, absorption and transportation of substances, resistance to biotic and abiotic stresses, as well as their application in agriculture has been investigated.

The structural and energetic characteristics of O3-H2O complexes have been investigated by means of B3LYP, MP2, MP4 (SDTQ), CCSD (T) and QCISD (T) methods in conjunction with AUG-cc-pVDZ and AUG-cc-pVTZ basis sets. Six conformers were found for the O3- H2O complex. Two different intermolecular interactions were expected to participate in the formation of complexes, namely conventional O¼H hydrogen bonding and O¼O interaction. The most stable structure is non-hydrogen bonded one with double O¼O interactions. The binding energies of the most stable complex, corrected with BSSE and ZPE, range from -5.99 to -12.20 kJ mol-1 at CCSD (T) /AUG-cc-pVTZ, QCISD (T) /AUG-cc-pVTZ and MP4 (SDTQ) /AUG-cc-pVTZ high levels of theory. The equilibrium distance between centers of monomers (O3¼OH2) in the most stable complex at the CCSD (T) /AUG-cc-pVDZ and CCSD (T) /AUG-cc-pVTZ levels is 2.9451 and 2.9448 Ao, respectively, in good agreement with the experimental value of 2.957 Ao. The AIM calculations predict that the O¼O and O¼H interactions in O3-H2O complexes are electrostatic in nature.

In this study, the adsorption efficiency of a low-cost biodegradable adsorbent, poly (AAC-co-AM)/AC biocomposite hydrogel prepared by a green method using free radical copolymerization was studied to remove heavy metals such as copper ions. Several analyses of the hydrogel were performed, such as field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The effect of some optimal conditions, such as copper ion concentration, equilibrium time, hydrogel weight, and solution temperature, was studied in the batch model. The adsorption of copper ion increased from 73.25% to 92.91% with a rising weight of hydrogel (0.01-0.1 g/50 mL) but with the increase in weight of the hydrogel, degrease the adsorption efficiency from 27.14 to 219.14 mg/g at a fixed concentration of copper ion 30 mg/L, equilibrium time of 1 h, temperature 25 °C, and agitation speed 150 rpm. Finally, as the temperature increases, the adsorption efficiency and removal percentage increase. Adsorption equilibrium studies were investigated by Langmuir and Freundlich isotherm models. The Freundlich model provided the result with better efficiency (Qe=84.567 mg/g). Calculations of non-covalent interaction, RDG, and Quantum chemical parameters are used in this study to confirm the real binding between metal ions and surfaces.

[Pd (FLU)2X2].yH2O.zCH3OH (FLU = flubendazole; X = Cl (1), y = 0, z = 0; X = Br (2), NO3(3), y = 2, z = 0; X = SCN (4), y = 2, z = 3) were synthesized as potential anticancer complexes, and their structures were elucidated using elemental analysis, TG/DTA, IR, 1H NMR, UV–vis., and conductivity measurements. FLU interacts with Pd (II) ions as a neutral unidentate ligand via the pyridine-type nitrogen of the benzimidazole ring. Geometry optimization, molecular electrostatic potential maps and natural bond orbital analysis were performed by DFT/B3LYP method. FLU, in comparison to its complexes, was screened for its antibacterial and cytotoxic activity. Complexes 1–4 possess strong anticancer activity with IC50 values (4.13–3.68 mg ml-1) compared with 3.57 mg ml-1 reported for cis-platin. The cytotoxicity was shown to be affected by the nature of the anion, where the sequence is 3 > 2 > 4 > 1 in case of MCF7 cell line. Structural-activity relationships suggested that EHOMO, energy gap and dipole moment were the most significant descriptors for the correlation with the antitumor activity.