Current Physical Chemistry - Volume 9, Issue 3, 2019

In this review, we discuss the rational design of a new class of lanthanide-doped organometallic nanostructured materials called 'molecular minerals'. Molecular minerals are nanostructured materials with a ceramic core made from chalcogenide groups and other heavy metals. Part of the central core atoms is replaced by suitable lanthanide atoms to impart fluorescent spectral properties. The ceramic core is surrounded by various types of organic networks thus making the structure partly ceramic and organic. The central core has superior optical properties and the surrounding organic ligand makes it easy to dissolve several kinds of organic solvents and fluoropolymers to make several kinds of active and passive photonic devices. This chapter starts with elaborate design strategies of lanthanidebased near-infrared emitting materials followed by the experimental results of selected near-infrared emitting lanthanide clusters. Finally, their potential applications in telecommunication, light-emitting diodes and medical imaging are discussed.

Introduction: Hydroxyapatite, Ca10 (PO4)6(OH)2, a ceramic material is the major inorganic component in bones and teeth of animals and humans. Although erbium is one of the prominent representative elements among the lanthanides, erbium doped hydroxyapatite has not been studied to a greater extent. This study reports the synthesis of erbium doped hydroxyapatite using the simple precipitation method and its structural and optical properties. Objectives: The primary objective of this study was to synthesize erbium doped hydroxyapatite and to study the structural and optical properties. Materials and Methods: Nanocrystalline erbium doped hydroxyapatite was successfully prepared using simple precipitation method. Average particle size of the synthesized particle was around 8-10 nm. Results: The typical absorption spectra of the erbium doped hydroxyapatite sample shows almost well defined peaks of the erbium ions. The absorption bands were observed at 360 nm, 373 nm, 448 nm, 490 nm, 524 nm and at 653 nm. The photoluminescence spectrum showed the presence of a green band at 550 nm and a red band which peaked at 750 nm. Conclusion: Spherical shaped nanocrystalline hydroxyapatite, Ca10 (PO4)6(OH)2 substituted with Erbium(III) were obtained using precipitation method. The synthesized Er3+ doped hydroxyapatite can be used for biophotonic applications, which exploits their exquisite optical properties and infrared imaging and several other therapeutic applications.

Introduction: Rare earth-doped Upconverting Nanoparticles (UCN's) can convert near-infrared photons into visible photons via multiphoton processes, which makes it a good material for generating white light. The production of luminescent materials for technology applications focuses on controlling powder characteristics such as chemical homogeneity and low impurity levels. Objective: In this research study, we synthesized Er3+ (1%) Tm3+ (1%) Yb3+ (at different percentages) by co-doping Y2O3 NPs, using the Controlled-Pressure Hydrothermal Method (CPHM), with nitrogen. The ratio used was chosen to conduct a detailed photolumniscence analysis. Methods: Samples of Y2O3: Er3+ (1%) Tm3+ (1%) Yb3+ (at 1.5%, 2%, and 2.5%) were prepared using the controlled-pressure hydrothermal method (CPHM). Each solution was transferred into a mini-clave drive Büchiglasuster with an inner Teflon vessel. In this case, the mini-clave was heated at 190°C for 3 h, and nitrogen was used to control the pressure. The initial pressure was 20 bars; it was increased during the process to 42 bars. The powders obtained were washed with distilled water using centrifugation at 4000 rpm for 15 min. The washed product was dried to 120°C, followed by subsequent heat treatment at 1000°C for 5 h. Results: The representative XRD patterns for the Y2O3: Er3+ (1%) Tm3+ (1%) and Yb3+ (at 1.5%, 2%, 2.5%) doped samples confirms the presence of a cubic Y2O3 crystal structure. Scanning Electron Microscope (SEM) images show that the morphology of these particles is spherical. Upconversion photoluminescence spectra of Y2O3:Er3+ (1% mol) Tm3+ (1% mol) Yb3+ (1.5% mol), Yb3+ (2.0% mol), and Yb3+ (2.5% mol), after 908-nm excitation. Blue, green, and red bands are centred at 440 nm, 469 nm, 618 nm, and 678 nm, respectively. Conclusion: The controlled-pressure hydrothermal method is a productive method for synthesizing rare earth-doped and codoped Y2O3; when Er3+, Yb3+, and Tm3+ ions are introduced into the host matrix, they do not cause any changes in the cubic structure nor influence the crystal structure. This method can used to synthesize any type of nanoparticle, because it involves low pressure (10-20 bars), low temperatures, and short time reactions.

Background: Phenothiazines and Triphenodithiazines are included in the class of nitrogen and sulphur donating ligands. They have a wide spectrum of biological activities and form important class of heterocyclic compounds. Both drugs are being used as, antitumors, anti-inflammatory, antiviral, anaesthetics, anticancer agents, antimalarials, antimicrobials, anti-cholinergics, growth inhibitors, and many other pharmacological agents. Objective: Present work has been initiated with a view to obtain a profile regarding structural insight of complexes of Cobalt (II), Ni (II) and Zinc (II) soaps derived from substituted phenothiazines 15 and triphenodithiazines using latest technique. It also gives an account of micelle formation in the mixed non aqueous solvents. Methods: The viscosity, specific viscosity, and fluidity of complexes of Co, Ni, and Zn Oleate with substituted phenothiazine and triphenodithiazine in methanol + benzene solvents was determined at a constant temperature of 303.15 K to study the micellar features and critical micelle concentration (CMC). In the present work benzene+ methanol have selected as co solvents due to these interact with complex molecules and thus affected aggregation of complex molecules. Results: The results were used to determine the CMC, soap complex-solvent interactions and the effect of chain length of the surfactant molecule on various parameters. The conclusions concerning solute-solute and solute-solvent interaction were discussed regarding the well-known Moulik’s and Jones-Dole equations. Conclusion: From above results it may be concluded that the micelle formation take place earlier in the case of triphenodithiazine complexes due to larger molecular structure, so a smaller number of molecules are needed to form micelle. Micellization also confirms the existence of complex aggregation in the non-aqueous mixed solvents. To conclude, it can be unveiled on the basis of the result acquired that above study of complexes conforms the presence of complex aggregation in the non - aqueous mixed solvents.