ABSTRACT A kinetic study of the cobalt electrodeposition onto a carbon fiber ultramicroelectrode of 11 μm of diameter was conducted in overpotential conditions from an aqueous solution containing 0.01 M CoCl2 + 0.1 M NH4Cl. From the voltamperometric and chronoamperometric studies, it was found that the value of the diffusion coefficient is 1.2x10−5 cm2 s−1. The analysis of the current density transients suggests that cobalt electrodeposition onto a carbon fiber electrode follows an instantaneous nucleation process controlled by spherical diffusion mass transport. Also, the number of active nucleation sites increases as the applied potential decreases.

ABSTRACT A new amlodipine-chitosan nanocomposite was built using amlodipine nanoparticles as primary scaffolds by spontaneous emulsification, and its complete elucidation was performed by using several spectrometric techniques. Our results indicate that the amlodipine-chitosan nanocomposite has better solubility than amlodipine at pH 7.4 with a nearly all the drug substance dissolved (97%) by the final time-point measured. The docking study support the existence of intermolecular interactions are established between amlodipine and chitosan.

Abstract: Dye-sensitized solar cells (DSSCs) based on triphenylamine (TPA) as a donor group linked with the acceptor cyanoacrylic acid electron acceptor by 2,2’-bithiophene as π-bridged (D-π-A) has been investigated by Density Functional Theory (DFT) at the B3LYP/6-311G(d,p) level of theory, to establish the conformational orientation of cyanoacrylic acid group as well as evaluate the effect of planarizing the 2,2’-bithiophene unit in position 3 and 3’ by electron withdrawing or donor groups on the electronic structure properties of ground and doping(n,p) states. Also, the Time Dependent Density Functional Theory (TD-DFT) at the CPCM-TD-CAM-B3LYP//CAM-B3LYP/6-311G(d,p) level of theory were selected to modulate the electronic absorption spectra and charge-transfer capabilities of the molecules analyzed in the present work. The results indicate that adding an auxiliary donor or withdrawing group to the 2,2’-bithiophene in the (D-π-A) arrangement allow to modify the LUMO’s energy of the dyes, while the HOMO's energy is slightly affected.

ABSTRACT Four acceptor-donor organic conjugated molecules based on thieno[3,4-b]pyrazine-terthienyls were analyzed in order to explore the effect of the donor substituent on their molecular structures, electronic and optical properties. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD/DFT) calculations were carried out employing the B3LYP hybrid functional in combination with the 6-31G(d,p) basis set. The results suggests that the addition of electron-donating substituents to the conjugated molecules can diminish their energy gap value, which is beneficial to the photon harvesting. The lowest-lying absorption spectra of compounds substituted with electron donor groups exhibited a red-shift and a high oscillation factor compared with the unsubstituted molecule. Additionally, the ionization potential (IP), electron affinity (EA), reorganization energy (λ) and open-circuit voltage (Voc) of the molecules were evaluated. According to these values, the molecules show good photovoltaic properties, and efficient charge transfer for hole and electron and balanced charges.

In this work, we studied the reactivity of picloram in the aqueous phase at the B3LYP/6-311++G(2d,2p) and MP2/6-311++G(2d,2p) levels of theory through global and local reactivity descriptors. The results obtained at the MP2 level indicate that the cationic form of picloram exhibits the highest hardness while the anionic form is the most nucleophilic. From the Fukui function values, the most reactive site for electrophilic and free radical attacks are on the nitrogen in the pyridine ring. The more reactive sites for nucleophilic attacks are located on the nitrogen atom of the amide group and on the carbon atoms located at positions 2 and 3 in the pyridine ring.