Carbon Nitride Quantum Dot-Embedded Poly(vinyl alcohol) Transparent Thin Films for Greenish-Yellow Light-Emitting Diodes

Recently, freestanding polymer thin films encapsulated with nanostructures have attracted the significant attention of the scientific community due to their promising application in portable optoelectronic devices. In this research contribution, we have fabricated a freestanding polymer thin film of poly­(vinyl alcohol) (PVA) encapsulated with carbon nitride quantum dots (CN-QDs) using the casting method, for the first time. The PVA polymer matrix provides mechanical support as well as dispersion of the CN-QDs preventing its solid-state quenching. From UV–visible spectra, it is revealed that optical transparency decreases with an increase in the concentration of CN-QDs within the PVA polymeric thin film. Such kind of decrease in optical transparency is one of the crucial factors for the optical concert of a nanomaterial. Interestingly, we have optimized the synthesis protocol to retain 40% transparency of the thin film by incorporating 10 wt % CN-QDs along with PVA without deteriorating its optical behavior. It is observed that when CN-QDs are embedded in the PVA matrix, emission becomes independent of excitation wavelength and is localized in the 510–530 nm region of the spectrum. Thus, the films exhibit excellent greenish-yellow emission when excited at 420 nm with the Commission Internationale de l’èclairage (CIE) coordinates (0.39, 0.46) and a correlated color temperature (CCT) of 4105 K. These excellent optoelectronic properties make them a promising candidate for practical phosphor applications. In a nutshell, this study demonstrates a promising way to exhibit the luminescence potential of freestanding polymer/CN-QD films in CN-QD-based solid-state lighting systems

Legislative Documents

Also, variously referred to as: House bills; House documents; House legislative documents; legislative documents; General Court documents

Polyamide–Polyamine Cryptand as Dicarboxylate Receptor: Dianion Binding Studies in the Solid State, in Solution, and in the Gas Phase

Polyamide–polyamine hybrid macrobicycle <b>L</b> is explored with respect to its ability to bind α,ω-dicarboxylate anions. Potentiometric studies of protonated <b>L</b> with the series of dianions from succinate (suc^2–) through glutarate (glu^2–), α-ketoglutarate (kglu^2–), adipate (adi^2–), pimelate (pim^2–), suberate (sub^2–), to azelate (aze^2–) have shown adipate preference with association constant value of <i>K</i> = 4900 M^–1 in a H₂O/DMSO (50:50 <i>v/v</i>) binary solvent mixture. The binding constant increases from glu^2– to adi^2– and then continuously decreases with the length of the anion chain. Further, potentiometric studies suggest that hydrogen bonding between the guest anions and the amide/ammonium protons of the receptor also contributes to the stability of the associations along with electrostatic interactions. Negative-mode electrospray ionization of aqueous solutions of host–guest complexes shows clear evidence for the selective formation of 1:1 complexes. Single-crystal X-ray structures of complexes of the receptor with glutaric acid, α-ketoglutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid assist to understand the observed binding preferences. The solid-state structures reveal a size/shape complementarity between the host and the dicarboxylate anions, which is nicely reflected in the solution state binding studies