QSAR models for the ozonation of diverse volatile organic compounds at different temperatures.

In order to assess the fate and persistence of volatile organic compounds (VOCs) in the atmosphere, it is necessary to determine their oxidation rate constants for their reaction with ozone (kO3). However, given that experimental values of kO3 are only available for a few hundred compounds and their determination is expensive and time-consuming, developing predictive models for kO3 is of great importance. Thus, this study aimed to develop reliable quantitative structure-activity relationship (QSAR) models for 302 values of 149 VOCs across a broad temperature range (178-409 K). The model was constructed based on the combination of a simplified molecular-input line-entry system (SMILES) and temperature as an experimental condition, namely quasi-SMILES. In this study, temperature was incorporated in the models as an independent feature. The hybrid optimal descriptor generated from the combination of quasi-SMILES and HFG (hydrogen-filled graph) was used to develop reliable, accurate, and predictive QSAR models employing the CORAL software. The balance between the correlation method and four different target functions (target function without considering IIC or CII, target function using each IIC or CII, and target function based on the combination of IIC and CII) was used to improve the predictability of the QSAR models. The performance of the developed models based on different target functions was compared. The correlation intensity index (CII) significantly enhanced the predictability of the model. The best model was selected based on the numerical value of Rm2 of the calibration set (split #1, Rtrain2 = 0.9834, Rcalibration2 = 0.9276, Rvalidation2 = 0.9136, and calibration = 0.8770). The promoters of increase/decrease for log kO3 were also computed based on the best model. The presence of a double bond (BOND10000000 and $10 000 000 000), absence of halogen (HALO00000000), and the nearest neighbor codes for carbon equal to 321 (NNC-C⋯321) are some significant promoters of endpoint increase.

A stage-structured population model for activity-dependent dendritic spines.

Here we present a novel application of stage-structured population modelling to explore the properties of neuronal dendrites with spines. Dendritic spines are small protrusions that emanate from the dendritic shaft of several functionally important neurons in the cerebral cortex. They are the postsynaptic sites of over 90% of excitatory synapses in the mammalian brain. Here, we formulate a stage-structured population model of a passive dendrite with activity-dependent spines using a continuum approach. This computational study models three dynamic populations of activity-dependent spine types, corresponding to the anatomical categories of stubby, mushroom, and thin spines. In this stage-structured population model, transitions between spine type populations are driven by calcium levels that depend on local electrical activity. We explore the influence of the changing spine populations and spine types on the development of electrical propagation pathways in response to repetitive synaptic input, and which input frequencies are best for facilitating these pathways.

A detailed computational investigation on the structural and spectroscopic properties of propolisbenzofuran B.

This investigation deals with some structural and spectroscopic aspects of propolisbenzofuran B molecule as one of the most important bioactive molecules which exists in the bee propolis composition. FT-IR vibrational analysis carried-out at B3LYP/6-311++G(d,p) level of the theory. 1H and 13C NMR chemical shift have been predicted with GIAO method. TD- DFT calculations have been established to predict the UV- Vis spectral analysis for propolisbenzofuran B molecule. The detailed structural analysis such as electronic characterization, HOMO and LUMO, DOS plot, Molecular Electronic Potential (MEP), Natural Bond Orbital (NBO) are performed and discussed for studied molecule.

Molecular Investigations of the Newly Synthesized Azomethines as Antioxidants: Theoretical and Experimental Studies.

BACKGROUND: In this study, the antioxidant property of new synthesized azomethins has been investigated as theoretical and experimental. METHODS AND RESULTS: Density functional theory (DFT) was employed to investigate the Bond Dissociation Enthalpy (BDE), Mulliken Charges, NBO analysis, Ionization Potential (IP), Electron Affinities (EA), HOMO and LUMO energies, Hardness (η), Softness (S), Electronegativity (µ), Electrophilic Index (ω), Electron Donating Power (ω-), Electron Accepting Power (ω+) and Energy Gap (Eg) in order to deduce scavenging action of the two new synthesized azomethines (FD-1 and FD-2). Spin density calculations and NBO analysis were also carried out to understand the antioxidant activity mechanism. Comparison of BDE of FD-1 and FD-2 indicate the weal antioxidant potential of these structures. CONCLUSION: FD-1 and FD-2 have very high antioxidant potential due to the planarity and formation of intramolecular hydrogen bonds.

Cu-MOF: an efficient heterogeneous catalyst for the synthesis of symmetric anhydrides via the C-H bond activation of aldehydes.

In this paper, an efficient and straightforward synthetic approach for the preparation of a number of symmetric carboxylic anhydrides was reported using Cu2(BDC)2(DABCO) as an efficient heterogeneous catalyst via the C-H bond activation of aldehydes with excellent yields and simple work up. This C-H bond activation reaction appears simple and convenient, has a wide substrate scope and makes use of cheap, abundant, and easily available reagents. The Cu-MOF catalyst was recycled and reused four times without any loss of catalytic activity.

Catalyst-free sonosynthesis of highly substituted propanamide derivatives in water.

A clean, rapid and energy-efficient approach to catalyst-free one-pot synthesis of highly substituted propanamide derivatives in water was developed utilizing of the ultrasonic irradiation. The method has been successful in achieving the green chemistry objective. A catalyst-free operation, an energy efficient protocol using ultrasound irradiation instead of conventional heating or stirring and use of water as a non-hazardous, inexpensive and readily available solvent in the one-step reaction against sequential reaction steps thus combining the features of both economic and environmental advantages.

Ultrasonics in isocyanide-based multicomponent reactions: a new, efficient and fast method for the synthesis of fully substituted 1,3,4-oxadiazole derivatives under ultrasound irradiation.

A fast and convenient approach to the synthesis of fully substituted 1,3,4-oxadiazoles via three-component reaction of aromatic carboxylic acids, acenaphthoquinone, and (N-isocyanimino)triphenylphosphorane under ultrasound irradiation is described. Furthermore, a series of compounds were synthesized and characterized by melting point, IR, NMR and MS. Utilization of easy reaction conditions, very high to excellent yields, and short reaction times makes this manipulation potentially very useful.

Novel, fast and efficient one-pot sonochemical synthesis of 2-aryl-1,3,4-oxadiazoles.

Ultrasound promoted synthesis of 2-aryl-1,3,4-oxadiazoles at ambient temperature is reported. The remarkable features of the new procedure are shorter reaction time, excellent yields, cleaner reaction profile and simple experimental and workup procedure.