Acid Blue 129 and Salicylate Cointercalated Layered Double Hydroxides: Assembly, Characterization, and Photostability

Advancing Chlorophyll Photostability: Dual Physicochemical Protection via Ce-Doped Hydrotalcite Organic-Inorganic Hybrid Pigments

In pursuit of enhancing the photostability of chlorophyll, a novel organic-inorganic hybrid pigment has been synthesized via a supramolecular intercalation assembly method, incorporating cerium-ion-doped hydrotalcite as the host matrix and chlorophyll as the intercalated guest molecule. This innovative pigment amalgamates the vivid coloration properties of organic dyes with the robust stability characteristic of inorganic substances. Determined from the detailed investigation of the structural evolution of chlorophyll during photodegradation, the dual physicochemical protection mechanism is critical to the advancement of chlorophyll photostability. It leverages the oxygen barrier attributes of the hydrotalcite's laminate structure and the ultraviolet light absorption and scattering capabilities of CeO2 nanoparticles formed in situ. Furthermore, Ce-doping introduces a redox cycle between Ce4+ and Ce3+ ions, which serves as a chemical defense by neutralizing reactive oxygen species that emerge during chlorophyll degradation. This multifaceted approach results in a substantial enhancement of photostability, with the hybrid pigment containing 0.3 Ce doped content, demonstrating a mere 5.90% alteration in reflectance at the 635 nm peak after 250 h of UV-accelerated aging. This breakthrough provides a dual physicochemical protective strategy that not only significantly prolongs the lifespan of chlorophyll pigments but also holds potential for broadening their application scope in various industries, including plastics and coatings, where color fastness and durability are paramount.

Construction of High Energy Nanoscale Lead Azide Composite with Improved Flame Sensibility from Intercalated Hydroxide

It is of great significance to develop efficient methods for preparing high-content modified nanoscale lead azide (LA) composites used in microinitiating devices. In this work, a structurally controllable salicylate-intercalated lead hydroxide with a nanoscale mesoporous structure is designed. Using it as a precursor, carbon-based lead azide (LA/C) and salicylate-based lead azide (LA/SA) are fabricated by the gas-solid azidation of the framework (GAF) method within 3 h, greatly reducing the preparation time of nano-LA composites. The characterizations of the composites demonstrate that the Pb in the precursors is transformed into nanoscale LA attached to the salicylate radical or its carbonized skeleton. Due to the unique embedded nanostructures and excellent electrical and thermal conductivity of salicylate-derived carbon materials, LA/C exhibits excellent electrostatic safety (E50 = 0.25 J) and flame sensitivity (H50 = 28 cm). The adjustable organic-inorganic ratio of intercalated hydroxides allows the LA content in LA/C to reach as high as 92.5%, enabling 6.50 mg of LA/C to successfully detonate secondary explosive CL-20 in a microinitiating device, demonstrating an amazing detonation ability superior to other reported LA complexes. The research provides a new perspective for the development of nanoscale LA composites with high LA content and appropriate sensitivity.

Exploring the Inclusion Complex of a Drug (Umbelliferone) with α-Cyclodextrin Optimized by Molecular Docking and Increasing Bioavailability with Minimizing the Doses in Human Body

In this study, umbelliferone and α-cyclodextrin host molecules have been mixed up through a coprecipitation method to prepare a supramolecular complex to provide physical insights into the formation and stability of the inclusion complex (IC). The prepared hybrid was characterized by ¹H nuclear magnetic resonance (¹H NMR), Fourier transform infrared (FTIR) spectroscopy, electrospray ionization (ESI) mass spectrometry, DSC, and fluorescence spectroscopic studies. Job's plot provides a stoichiometric ratio of 1:1 and the Benesi-Hildebrand double reciprocal plot gives binding constant values using fluorescence spectroscopic titrations and the ESI mass data support the experimental observations. The results of molecular modeling were systematically analyzed to validate the inclusion complexation. In preliminary computational screening, α-cyclodextrin IC of umbelliferone was found to be quite stable based on the docking score, binding free energies, and dynamic simulations. In addition, the results obtained from ¹H NMR and FTIR spectroscopy studies supported the inclusion complexation phenomenon. The results obtained from computational studies were found to be consistent with the experimental data to ascertain the encapsulation of umbelliferone into α-cyclodextrin.

Luminescent Carrier, Tb3+-Doped Layered Yttrium Hydroxide, for Delivery Systems

Layered rare-earth hydroxides (LRHs) with high anion exchangeability between the hydroxocation layers, where a large variety of organic anions can be sheltered, are employed to construct hybrid systems that slowly release active organic ingredients. More importantly, it is possible to endow LRHs with a photoluminescence capability by doping activator ions such as Ce³⁺, Eu³⁺, and Tb³⁺ into matrices. In the present work, we explored Tb³⁺-doped layered yttrium hydroxide Y_1.80Tb_0.20(OH)₅Cl· nH₂O (LYH:Tb) nanosheets as a luminescent carrier for sustained release of salicylic acid (2-hydroxybenzoic acid), an example of nonsteroidal anti-inflammatory drugs and antimicrobial agents. Salicylate (sal) was intercalated into the interlayer gallery of LYH:Tb via a direct ion-exchange reaction. An observed variation in basal spacing suggested that salicylate anions are arranged in an interdigitated bilayer manner in the interlayer space of LYH:Tb. As generally observed in organic/inorganic hybrid systems, the thermal and photostabilities of salicylate were significantly improved after intercalation compared to its free state. The release kinetics of salicylate from sal-LYH:Tb hybrids in a saline solution at pH = 7.4 showed a highly sustained release of salicylate. Among various examined mathematical models, the parabolic diffusion equation best described the cumulative salicylate release. In particular, the salicylate intercalation led to the characteristic ⁵D₄ → ⁷F _J ( J = 6, 5, and 4) green emission of Tb³⁺ by its sensitization followed by the energy transfer to sal-LYH:Tb, whereas typical blue emission of salicylate was recovered after its release from the interlayer gallery of the LYH:Tb carrier. This green/blue luminescence change behavior provides a useful technique for in situ monitoring of the delivery and release of salicylate at target sites. The sal-LYH:Tb hybrid, with antimicrobial properties, was readily dispersed into a biodegradable polymer, polyvinyl alcohol, to prepare a transparent, UV-shielding, and luminescent composite that is applicable as an antimicrobial polymer to retard or prevent microbial growth.