Scrupulous recognition of biologically important acids by fluorescent “turn off-on” mechanism of thaicalix reduced silver nanoparticles

Water dispersible silver nanoparticles(AgNps) were prepared using thiacalix[4]arene tetrahydrazide(TCTH) as a reducing and stabilizing agent.TCTH-AgNps were characterized by surface plasmon resonance(SPR),transmission electron microscopy(TEM) and energy dispersive X-ray(EDX).Relatively uniform 20 nm spherical particles of TCTH-AgNps were efficiently formed over a pH range of 5-9 and from 10-40 ℃.The interaction behavior of TCTH-AgNps with different amino acids was investigated using spectrophotometry and spectrofluorimetry.Among the amino acids tested,only tryptophan and histidine showed fluorescence quenching and fluorescence enhancement,respectively.The linear detection range by Stern-Volmer plot was 5 nmol/L to 0.48 μmol/L for tryptophan and 4 nmol/L to 0.54 μmol/L for histidine.TCTH-AgNps were able to effectively reduce the levels of gram-positive bacteria,gram-negative bacteria,and fungi.These properties argue for the potential use of TCTH-AgNps as detectors of histidine and tryptophan and as antibiotics.     

Efficient Transition‐Metal‐Free Oxidation of Benzylic and Secondary Alcohols to the Carbonyl Compounds Using an N‐Bromosuccinimide/NH4Cl System

The oxidation of a variety of benzylic and secondary alcohols was achieved in excellent yields using an NBS/NH₄Cl system in aqueous acetonitrile (CH₃CN‐H₂O; 7/3 v/v) at 80°C under very mild conditions.     

Direct synthesis of Poly(Ԑ-Caprolactone)-block-poly (glycidyl methacrylate) copolymer and its usage as a potential nano micelles carrier for hydrophobic drugs

Ring-opening (ROP) and enzymatic copolymerization (ECP) are among the most widely used approaches for synthesizing copolymers of polycaprolactone (PCL). It involves multiple-step reactions and the utilization of enzymes that make the process a lot more complicated, time consuming, and expensive. Atom transfer radical polymerization (ATRP) has been adopted to synthesize a novel amphiphilic copolymer in our study. The study presents a method to eliminate the ROP/ECP multiple steps in monomer polymerization thus making the process simpler and smoother. The synthesis of cationic polymer micelles copolymer of PCL-PGMA (polycaprolactone grafted poly glycidyl methacrylate) was carried out using direct functionalization of hydroxy group in crude PCL to achieve a higher degree of functionalization, i.e., 12.8% for macroinitiator. FTIR and ¹H-NMR confirmed the successful synthesis of the copolymer with better control over the molecular weight with a PDI (1.84). DSC and XRD results showed the reduction of crystallinity by 86.81%, making copolymer more compatible for drug delivery application. The synthesized copolymer was further converted to nano-micelles drug carrier having an average size of 96.08 ± 21.22 nm. The drug encapsulation efficiency achieved was 60.0 ± 1.7%, and nano-micelles rendered a slow and controlled release of naproxen with long-term storage stability.     

Organic-Free Interzeolite Transformation in the Absence of Common Building Units

Zeolite crystals can be used as seeds or aluminosilicate sources in syntheses to control polymorphs and/or reduce the quantity of organics used as structure-directing agents. A frequently invoked hypothesis for interzeolite transformations is that zeolites share some underlying similarity in structure, most notably in cases pertaining to organic-free syntheses. Herein, we show for the first time that ZSM-5 (MFI) can be directly obtained from USY (FAU) through an interzeolite transformation between parent–daughter structures lacking common building units in the absence of a structure-directing agent and seeds. We show that interzeolite transformation leads to a crystalline product with fewer defects. Our findings also reveal that ZSM-5 is a metastable intermediate that undergoes further transformation to mordenite (MOR) and quartz. The MFI-to-MOR transition is counter to reported trends for which transformations lead to structures with reduced molar volume. Herein, we propose mechanistic arguments that suggest the driving force for interzeolite transformation is more complex than guidelines posited in the literature.     

Ni(II) and Cu(II) complexes of bidentate thiosemicarbazone ligand: Synthesis,structural, theoretical,biological studies and molecular modeling

The conventional condensation and refluxing process was employed to synthesize Ni(II) and Cu(II) complexes of Methylcarbamatethiosemicarbazone ligand. Reactions were carried out at the pH of 7. The molar ratio of the ligand and metal salt was 2:1. The structures of the synthesized metal complexes were suggested by different analytical techniques such as magnetic susceptibility, molar conductance, IR, EPR and UV spectroscopy. Experimental studies confirmed the octahedral geometry for all the complexes. The geometry of the ligand and complexes were also confirmed by theoretical studies. The complexes were investigated for biological action against pathogenic fungi (C. krusei, C. albican) and bacteria (S. aureus, E. coli). The antimicrobial results confirmed superior inhibition potential of the metal complexes as compared with the parent ligand. The enhanced antimicrobial activities might be due to the chelation. Molecular-docking assays confirmed the strong interaction of ligand with target antimicrobial protein DNA gyrase-B.     

Ion implantation for semiconductor processing

The potential advantages of ion implantation have been exploited in virtually every kind of semiconductor device. Several commercially important devices owe their existence to this technique.

Ion implantation provides precise control over the amount of dopant, concentration profile and lateral dimensions in device fabrication. The high degree of uniformity and reproducibility have made it possible to produce sophisticated devices and integrated circuits with high yield and tight tolerances. This is a truly planar process. It is possible to achieve high doping concentrations with relatively lower processing temperatures thereby avoiding lifetime degradation. The process is carried out in an inherently clean environment. A wide range of dopants is available and one is not limited by the particular properties of the substrate. There is great flexibility in choice of masking materials and self-alignment of doped regions in MOS devices is facilitated.

The increasing impact of ion implantation on device technology is discussed with reference to some recent developments. Specific commercially manufactured devices are mentioned.

Ion implantation machines continue to undergo development aimed at higher throughputs and cleaner vacuum. There is the need for greater reliability of machines. Effort is also directed at the development of low cost machines for dedicated applications.

Design of implanted devices continues to be an empirical process in some respects. The ability to accurately predict profile shapes in samples implanted (perhaps through a screen oxide) and subject to complicated post-implantation process steps, would cut down development time and costs.     

Novel Fluorinated Spiro [Indole-indazolyl-thiazolidine]-2,4′-diones: Design and Synthesis

The reaction of indol-2,3-diones ( 1a–i ) with 5-aminoindazole ( 2 ) has resulted in the formation of hitherto unknown 3-(indazol-5-yl)iminoindol-2-ones ( 3a–i ) in quantitative yields which, on 1,3-dipolar cyclocondensation with mercaptoacetic acid ( 4 ), has afforded a series of new spiro heterocycles, 3′-(indazol-5-yl) spiro[3H, indol-3, 2′ -thiazolidine]-2,4′-diones* ( 5a–i ).