Synthesis and Characterization of Zinc (II) Phthalocyanine for Screening Potential Solar Cell Dye Application

Phthalocyanine molecules have the potential to be used in select Dye Sensitized Solar Cells (DSSCs) and Luminescent Solar Concentrators (LSCs), due to UV-Vis absorbance in the 300-450 (nm) Soret Band, corresponding to π HOMO-1 to π* LUMO transition and 550-690 (nm) Q-band, corresponding to π HOMO to π* LUMO transitions. In this study Tetranitro Zinc (II) Phthalocyanine is synthesized via base catalysis before the product is characterized via IR, 1H NMR & UV-Vis analysis. Assessing the desirability of the Tetranitro Zinc (II) Phthalocyanine as a solar organic semiconducting dye in DSSCs and LSCs. The desirability is assessed by novel computational DFT calculations, of the aggregation binding mode to deduce if Aggregation-Caused Quenching (ACQ) is occurring in the aggregated sample. ACQ is known to reduce DSSCs and LSCs generation of useful photo-active current. Aggregation-Caused Quenching (ACQ) is mathematically indicated in Phthalocyanine aggregation and Tetranitro Zinc (II) Phthalocyanine’s desirability is assessed for further use in DSSCs and LSCs.

Stereoselective Michael Additions of Arylacetic Acid Derivatives by Asymmetric Organocatalysis

Because of the versatility of chiral 1,5-dicarbonyl structural motifs, the development of stereoselective Michael additions of arylacetic acid derivatives to electron-deficient alkenes is an important challenge. Over recent decades, an array of enantio- and diastereoselective methods of this type have been developed through the use of chiral organocatalysts. In this article, three distinct strategies in this research area are highlighted. Catalytic generation of either a chiral iminium electrophile (iminium catalysis) or a chiral enolate nucleophile (Lewis­ base catalysis) has allowed the efficient construction of stereogenic C–C bonds. We also introduce a synergistic catalytic approach involving the merger of these two catalytic cycles that provides selective access to all four stereoisomers of products with vicinal stereocenters.1 Introduction2 Iminium Catalysis3 Lewis Base Catalysis4 Synergistic Organocatalysis5 Summary

Potentiality of Yellow Oleander (Thevetia Peruviana) Seed Oil as an Alternative Diesel Fuel in Compression Ignition Engines

Biodiesel has been accepted as a clean and an eco-friendly green diesel fuel by the entire world. In India, various non-edible oils have been tested for exploring their suitability as a fuel in diesel engines. In the north eastern states of India, many oil bearing seeds such as Koroch (a variety of Pongamia glabra), Nahar (Mesua ferrea), Terminalia (Terminalia belerica Robx), Kutkura (Meyna spinosa Roxb), Amari (Amoora Wallichii King), Yellow oleander (Thevetia peruviana) and others are found in abundance. In this article, the Yellow oleander seed oil (YOSO) has been investigated for biodiesel production and characterization. The oil content in Yellow oleander seed is found to be 63.87%. The free fatty acid (FFA) content in YOSO is measured, and is found to be 32.0%; hence the two-step acid-base catalysis transesterification process has been adopted for producing biodiesel from the YOSO. YOSO contains 5.03% palmitic, 6.92% stearic, 48.14% oleic and 31.37% linoleic acid. The density, calorific value and kinematic viscosity of Yellow oleander fatty acid methyl ester (YO-FAME) are 879.7 kg/m3, 40.159 MJ/kg and 4.63 mm2/s respectively. Most of the fuel properties of YO-FAME meet ASTM D6751 and EN 14214 biodiesel standards. The YO-FAME exhibits a low sulphur content of 13.0 ppm and a high cetane number of 58.3. Fire point and pour point of YO-FAME were found to be 158°C and 5°C respectively. The physio-chemical properties of YO-FAME has been compared with FAME of Yellow oleander, Ratanjot (Jatropha curcus), Terminalia (Terminalia belerica Robx.) and Nahar (Mesua ferrea).

Spatiotemporal coordination of the RSF1-PLK1-Aurora B cascade establishes mitotic signaling platforms

The chromatin remodeler RSF1 enriched at mitotic centromeres is essential for proper chromosome alignment and segregation and underlying mechanisms remain to be disclosed. We here show that PLK1 recruitment by RSF1 at centromeres creates an activating phosphorylation on Thr236 in the activation loop of Aurora B and this is indispensable for the Aurora B activation. In structural modeling the phosphorylated Thr236 enhances the base catalysis by Asp200 nearby, facilitating the Thr232 autophosphorylation. Accordingly, RSF1-PLK1 is central for Aurora B-mediated microtubule destabilization in error correction. However, under full microtubule-kinetochore attachment RSF1-PLK1 positions at kinetochores, halts activating Aurora B and phosphorylates BubR1, regardless of tension. Spatial movement of RSF1-PLK1 to kinetochores is triggered by Aurora B-mediated phosphorylation of centromeric histone H3 on Ser28. We propose a regulatory RSF1-PLK1 axis that spatiotemporally controls on/off switch on Aurora B. This feedback circuit among RSF1-PLK1-Aurora B may coordinate dynamic microtubule-kinetochore attachment in early mitosis when full tension yet to be generated.

Remote-controlled exchange rates by photoswitchable internal catalysis of dynamic covalent bonds

The transesterification of boronate esters with diols is tunable over at least 14 orders of magnitude. Rate acceleration is achieved by internal base catalysis, which lowers the barrier for the proton transfer step. Here we report a photoswitchable internal catalyst that tunes the rate of boronic ester/diol exchange over at least 4 orders of magnitude. We employed an acylhydrazone molecular photoswitch, which forms a thermally stable but photoreversible intramolecular H-bond, to gate the activity of the internal base catalyst in 8-quinoline boronic esters. The photoswitch can be cycled repeatedly, with high photostationary states. The intramolecular H-bond is found to be essential to the design of this photoswitchable internal catalyst, as protonating the quinoline with external sources of acid has little effect on the exchange rate.