Ultrasound-assisted fabrication of a new nanocomposite electrode of samaria and borazon for high performance supercapacitors.

The fabrication of hetero structured materials with supercapacitor applications for industrial use remains a key challenge. This work reports a new supercapacitor material with high capacitance, comprising samaria and borazon (O3Sm2/BN) synthesized ultrasonically (40 ±â€¯3 kHz, 200 W). The successful synthesis, probable interfaces between O3Sm2 and BN and thermal stability of the nanocomposite were studied by UV-Vis. and FT-IR spectroscopies, X-ray diffraction (XRD) and thermo gravimetric analyses (TGA). The morphology of nanocomposite was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Elemental mapping analysis and energy dispersive X-ray analysis (EDAX) confirmed the elements present in the material. This supercapacitor material shows a maximum discharge capacitance of 414 Fg-1 at 0.25 Ag-1 and an exceptional retention of specific capacitance (92.5%) in 5000 cycles. Such nanocomposite with better specific capacitance and charge/discharge rates makes it a right candidate as next generation supercapacitor, which certainly finds applications in various unconventional energy storage devices.

Time-Dependent Density Functional Theoretical Investigation of Photoinduced Excited-State Intramolecular Dual Proton Transfer in Diformyl Dipyrromethanes.

In recent research [ Chem. Commun. 2014 , 50 , 8667 ], it was found that photoinduced enolization occurred in 1,9-diformyl-5,5-diaryldipyrromethane (DAKK) by excited-state dual proton transfer resulting in a red-shifted absorption, a phenomena not observed in 1,9-diformyl-5,5-dimethyldipyrromethane (DMKK) and 1,9-diformyl-5-aryldipyrromethane (MAKK). The observation was supported by preliminary density functional theoretical (DFT) calculations. In the work reported here, a detailed and systematic study was undertaken considering four molecules, 1,9-diformyldipyrromethane (DHKK), DMKK, MAKK, and DAKK and their rotational isomers using DFT methods. Different processes, namely, cis-trans isomerization and single and double proton transfer processes, and their mechanistic details were investigated in the ground and excited states. From the simulation studies, it was seen that the presence of different substituents at the meso carbon does not affect the λabs values during cis → trans isomerization. However, enolization by proton transfer processes were found to be influenced by the substituents, as seen in the experiments. Enolization was observed to follow a stepwise mechanism, that is, diketo → monoenol → dienol. While monoenols showed negligible substituent effects on the λabs values, a large red shift in λabs was seen only in DAKK, in agreement with the experimental findings. This observation can be attributed to the lowering of the keto → enol activation barrier, stabilization of DAEE in the S1 state, and the charge transfer nature of the transitions involved in DAEE.

Photophysical properties of bridged core-modified hexaphyrins: conjugational perturbation of thiophene bridges.

The role of thiophene bridges in determining the photophysical properties of bridged core-modified hexaphyrins is investigated. Depending on the substituted chalcogen atoms and conjugational perturbation across the thiophene bridges, the bridged core-modified hexaphyrins reveal unique photophysical properties.

In vitro demonstration of apoptosis mediated photodynamic activity and NIR nucleus imaging through a novel porphyrin.

We synthesized a novel water-soluble porphyrin THPP and its metalated derivative Zn-THPP having excellent triplet excited state quantum yields and singlet oxygen generation efficiency. When compared to U.S. Food and Drug Administration approved and clinically used sensitizer Photofrin, THPP showed ca. 2-3-fold higher in vitro photodynamic activity in different cell lines under identical conditions. The mechanism of the biological activity of these porphyrin systems has been evaluated through a variety of techniques: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, comet assay, poly(ADP-ribose)polymerase (PARP) cleavage, CM-H(2)DCFDA assay, DNA fragmentation, flow cytometric analysis, fluorescence, and confocal microscopy, which confirm the apoptotic cell death through predominantly reactive oxygen species (ROS). Moreover, THPP showed rapid cellular uptake and are localized in the nucleus of the cells as compared to Hoechst dye and Photofrin, thereby demonstrating its use as an efficient sensitizer in photodynamic therapy and live cell NIR nucleus imaging applications.

9,10,19,20-Tetraarylporphycenes.

meso-Tetraarylporphycenes, structural isomers of meso-tetraarylporphyrins, were synthesized by the acid-catalyzed oxidative coupling reaction for the first time which is an alternative synthetic methodology to the traditional McMurry coupling reaction. The structure of the macrocycle and Ni(II) complex are characterized by single-crystal X-ray diffraction analyses where both form 1-D supramolecular assembly.

Synthesis of N-confused tetraphenylporphyrin rhodium complexes having versatile metal oxidation states.

A variety of N-confused tetraphenylporphyrin rhodium complexes were synthesized, and their structures and physical properties were investigated. Depending on the reaction conditions, the rhodium(I), -(III), and -(IV) complexes were produced, which exemplified the versatile coordination mode of N-confused porphyrin ligands.

ansa-Metallocene-based cyclic[2]pyrroles.

Syntheses and X-ray structural analyses of ansa-metallocene-based cyclic[2]pyrroles are described. The pyrrole units in the macrocycles adopt partial 1,2-alternate conformation in the solid state.

A lipophilic hexaporphyrin assembly supported on a stannoxane core.

Lipophilic hexaporphyrin free-base and copper-metalated assemblies supported on a Sn6O6 core have been synthesized and characterized. The nuclease activity of the copper derivative has been studied.

Confusion approach to porphyrinoid chemistry.

N-confused porphyrin (NCP) is a porphyrin isomer that is different largely from the parent porphyrin, particularly in the physical, chemical, structural, and coordination properties. Introduction of the confused pyrrole into the normal and expanded porphyrins leads to generation of the confused porphyrinoids having rich structural diversity. In this Account, we introduce a series of N-confused porphyrinoids recently synthesized and highlight their properties such as fusion, peripheral N coordination, supramolecular assemblies, anion binding, and singlet-oxygen sensitization.

Doubly N-confused hexaphyrin: a novel aromatic expanded porphyrin that complexes bis-metals in the core.

Meso-hexakis(pentafluorophenyl)-substituted doubly N-confused hexaphyrins and their metal complexes were synthesized for the first time, and the structures were elucidated by X-ray single-crystal analyses. The free base form of oxidized hexaphyrin (5) had two preorganized N3O pockets in the macrocyclic core, where a hydrogen-bonding network was formed to keep the molecule planar (the mean plane deviation is 0.054 A). The formation of a planar bis-Cu(II) complex was confirmed by UV/vis, magnetic susceptibility measurements, and X-ray crystallography. The bis-Ni(II) complex (7), on the other hand, was distored from planarity, but it changed to the planar structure upon solvent (acetonitrile) coordination as judged by the observation of a sharp Soret-like band in absorption spectra and the X-ray structures of the complexes.