2 research outputs found
Meglumine: A Novel and Efficient Catalyst for One-Pot, Three-Component Combinatorial Synthesis of Functionalized 2‑Amino‑4<i>H</i>‑pyrans
An
efficient one-pot synthesis of functionalized 2-amino-4<i>H</i>-pyrans by a meglumine-catalyzed three-component reaction has been
developed. A broad range of substrates including aromatic and heteroaromatic
aldehydes, isatin derivatives, and acenaphthenequinone are condensed
with enolizable C–H activated compounds and alkylmalonates
to give the desired products in high to excellent yields. This methodology
provides an alternative approach for rapid access to construct a diversity-oriented
library of 4<i>H</i>-pyrans
Thickness-Dependent Optical Constants and Annealed Phase Transitions of Ultrathin ZnO Films
The thickness-dependent optical constants
and annealed phase transitions
of atomic-layer-deposited ZnO ultrathin films with a thickness of
less than 50 nm have been demonstrated by spectroscopic ellipsometry.
The thickness dependence of refractive index and extinction coefficient
was
discussed, and the mechanisms were given in the molecule level based
on previous reports. Furthermore, the optical properties of ZnO ultrathin
films varied with annealing temperatures, and the phase transition
was found at high annealing temperature. The thickness of the ultrathin
films decreased obviously, and the refractive index of the ultrathin
films changed a lot after annealing at high temperature while Zn<sub>2</sub>SiO<sub>4</sub> formed at a temperature above 800 °C.
The low phase transition temperature of Zn<sub>2</sub>SiO<sub>4</sub> may be due to the ultrathin scale effect. What’s more, photoluminescence
spectra showed the annealing effect on ultrathin films and the enhanced
defects luminescence were observed. We believe that these investigations
will help improved understanding of essential physical chemistry and
optoelectronic devices based on ultrathin oxide films for optical
and photoelectric applications