Optical applications of transition metal ion doped phosphate glasses

The transition metal ion-doped lithium phosphate glasses are prepared with a novel composition by melt quenching method, XRD patterns revealed their characteristic amorphous nature. The structural and physical properties of the prepared glasses are significantly varying with the increased concentration levels of dopant. Optical absorption and transmission spectra of the glass samples are analyzed. The absorption peaks are observed in ultraviolet, visible and infrared regions.The direct and indirect energy band gap values are decreasing while Urbach's energy values are increasing as the concentration levels of dopants are increasing. The obtained energy band gap values are in the range of semiconductor materials. The optical transmission spectra of these transition metal ion-doped glasses reveal their application as bandpass filters with filtering ability in UV or Visible regions at double and triple wavelengths and hence useful as dual band-pass filters. The glasses with <10 full width half maximum(FWHM) values are useful for narrowband lasers.

Synthesis, Characterization and Magnetic Susceptibility of Novel Transition Metal Ion Complexes with (E)-2-((7H-Purin-6-ylimino)methyl)phenol and Its Antibacterial Efficiency

The novel transition metal ion complexes were synthesized by refluxing the ethanolic solutions of metal acetates with Schiff base in 1:2 ratios. The structure and characterization of synthesized complexes of Mn (II), Co (II), Ni (II), Cu (II) and Zn (II) with Schiff base (E)-2-((7H-purin-6-ylimino)methyl)phenol were elucidated by using 1H NMR, FT-IR and UV-Visible spectroscopic techniques. The synthesized compounds were also been screened against gram positive and gram-negative bacteria. The novel compounds were further carried out for the study of magnetic susceptibility.

An improved fluorescent noncanonical amino acid for measuring conformational distributions using time-resolved transition metal ion FRET

With the recent explosion in high-resolution protein structures, one of the next frontiers in biology is elucidating the mechanisms by which conformational rearrangements in proteins are regulated to meet the needs of cells under changing conditions. Rigorously measuring protein energetics and dynamics requires the development of new methods that can resolve structural heterogeneity and conformational distributions. We have previously developed steady-state transition metal ion fluorescence resonance energy transfer (tmFRET) approaches using a fluorescent noncanonical amino acid donor (Anap) and transition metal ion acceptor to probe conformational rearrangements in soluble and membrane proteins. Here, we show that the fluorescent noncanonical amino acid Acd has superior photophysical properties that extend its utility as a donor for tmFRET. Using maltose-binding protein (MBP) expressed in mammalian cells as a model system, we show that Acd is comparable to Anap in steady-state tmFRET experiments and that its long, single-exponential lifetime is better suited for probing conformational distributions using time-resolved FRET. These experiments reveal differences in heterogeneity in the apo and holo conformational states of MBP and produce accurate quantification of the distributions among apo and holo conformational states at subsaturating maltose concentrations. Our new approach using Acd for time-resolved tmFRET sets the stage for measuring the energetics of conformational rearrangements in soluble and membrane proteins in near-native conditions.