Modeling the Properties of Curcumin Derivatives in Relation to the Architecture of the Siloxane Host Matrices

Research in the field of natural dyes has constantly focused on methods of conditioning curcumin and diversifying their fields of use. In this study, hybrid materials were obtained from modified silica structures, as host matrices, in which curcumin dyes were embedded. The influence of the silica network structure on the optical properties and the antimicrobial activity of the hybrid materials was monitored. By modifying the ratio between phenyltriethoxysilane:diphenyldimethoxysilane (PTES:DPDMES), it was possible to evaluate the influence the organosilane network modifiers had on the morphostructural characteristics of nanocomposites. The nanosols were obtained by the sol–gel method, in acid catalysis. The nanocomposites obtained were deposited as films on a glass support and showed a transmittance value (T measured at 550 nm) of around 90% and reflectance of about 11%, comparable to the properties of the uncovered support. For the coatings deposited on PET (polyethylene terephthalate) films, these properties remained at average values of T550 = 85% and R550 = 11% without significantly modifying the optical properties of the support. The sequestration of the dye in silica networks reduced the antimicrobial activity of the nanocomposites obtained, by comparison to native dyes. Tests performed on Candida albicans fungi showed good results for the two curcumin derivatives embedded in silica networks (11–18 mm) by using the spot inoculation method; in comparison, the alcoholic dye solution has a spot diameter of 20–23 mm. In addition, hybrids with the CA derivative were the most effective (halo diameter of 17–18 mm) in inhibiting the growth of Gram-positive bacteria, compared to the curcumin derivative in alcoholic solution (halo diameter of 21 mm). The results of the study showed that the presence of 20–40% by weight DPDMES in the composition of nanosols is the optimal range for obtaining hybrid films that host curcumin derivatives, with potential uses in the field of optical films or bioactive coatings.

Wide-range lifetime-tunable and responsive ultralong organic phosphorescent multi-host/guest system

The rational lifetime-tuning strategy of ultralong organic phosphorescence is extraordinarily important but seldom reported. Herein, a series of multi-host/guest ultralong organic phosphorescence materials with dynamic lifetime-tuning properties were reported. By doping a non-room-temperature phosphorescence emitter into various solid host matrices with continuously reduced triplet energy levels, a wide-range lifetime (from 3.9 ms gradually to 376.9 ms) phosphorescence with unchangeable afterglow colors were realized. Further studies revealed that the host matrices were employed to afford rigid environment and proper energy levels to generate and stabilize the long-live triplet excitons. Meanwhile, these multi-host/guest ultralong organic phosphorescence materials also exhibited excitation-dependent phosphorescence and temperature-controlled afterglow on/off switching properties, according to the virtue of various photophysical and thermal properties of the host matrices. This work provides a guiding strategy to realize lifetime-tuning ultralong organic phosphorescence with lifetime-order encoding characteristic towards widespread applications in time-resolved information displaying, higher-level security protection, and dynamic multi-dimensional anti-counterfeiting.

Slow and Fast Lights in Metal/Dielectric Composite of Cylindrical Nanoinclusions in Passive and Active Linear Dielectric Host Matrices

This paper presents theoretical discussions and computational numerical results obtained from the study of extreme values of the speed of light in metal/dielectric composite, where the cylindrical nanoinclusions are uniformly distributed in the linear dielectric host matrix. The results testify that, within our approach, at the region of anomalous dispersion, light can travel with a group velocity greater than the speed of light in vacuum. In a composite with passive host matrix, the light pulse is absorbed within a very small distance. The problem of absorption can be reduced considerably by using an active host matrix.

Immobilization of TiO2 Nanoparticles in Hydrogels Based on Poly(Methyl Acrylate) and Succinamide Acid for the Photodegradation of Organic Dyes

Hydrogels have excellent properties that make them ideally suited as host matrices for the immobilization of photoreactive materials such as TiO2 nanoparticles that serve as catalysts in the photodegradation of organic dyes, which is of great importance in practical water pollution treatment applications. However, the application of hydrogels for this purpose remains poorly studied. The present study addresses this issue by developing two types of hydrogels based on poly(methyl acrylate) and succinamide acid with embedded TiO2 nanoparticles for use as photocatalysts in the photodegradation of organic dyes. The results of the analysis demonstrate that the TiO2 nanoparticles are distributed uniformly in the hydrogel matrices, and the hydrogels maintain their original structures after use. The photodegradation efficiencies of the developed TiO2-hydrogels are demonstrated to be reasonably close to that of freely distributed TiO2 nanoparticles in solution for four different organic dyes. In addition, the results of degradation-regeneration cycling tests demonstrate that immobilizing the TiO2 nanoparticles into the hydrogels greatly reduces their loss during utilization, and the photocatalysts can be easily reused. In fact, the two TiO2-hydrogels retain reasonably high photocatalytic degradation performance after four degradation-regeneration cycles.

Poly(vinylidenefluoride) polymers and copolymers as versatile hosts for luminescent solar concentrators: compositional tuning for enhanced performance

Novel fluoropolymer–polymethylmethacrylate blends used as host matrices in luminescent solar concentrators (LSCs) are presented. Fluoropolymer/PMMA-based LSC efficiency is comparable to that of PMMA-based LSCs and is stable over 1000 h of aging test.