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This dissertation explores the multifaceted roles of rare-earth doped hydroxyapatite in biomedical applications, bridging the gap between luminescence studies and osteogenic potential in the context of bone tissue engineering and regenerative medicine. In the second chapter, we look into the luminescence properties of terbium, cerium, and europium doped hydroxyapatite scaffolds when immersed in simulated body fluid (SBF) over a four-week period. Our comprehensive study reveals a consistent decrease in luminescence emission intensity across all samples, accompanied by a reduction in the concentration of rare-earth ions within the scaffolds, as confirmed by energy dispersive spectroscopy. Furthermore, fluorescence spectroscopy demonstrates the translocation of these ions into the SBF, indicating the scaffolds' partial dissolution over time. The employment of rare-earth ions as luminescence markers offers profound insights into apatite formation mechanisms, presenting significant implications for the development of safer and more durable materials in biomedical applications.Expanding upon the foundational knowledge established in the first and second chapters, the third chapter investigates the osteogenic potential of rare-earth doped hydroxyapatite scaffolds using a murine pre-osteoblastic cell line. This study assesses the effects of ytterbium, terbium, cerium, and europium doping on osteoblast differentiation, gauged by alkaline phosphatase activity and the expression of osteogenic marker genes such as Runx2, OCN, ALP, OPN, and BMP2. Our findings indicate a notable enhancement in differentiation activity with the incorporation of rare-earth elements, with europium and ytterbium doped HAp showing superior performance. Cathodoluminescence spectroscopy further corroborates these results by revealing distinct emission peaks specific to the Eu2+/Eu3+ and Yb2+ ions, underscoring the role of valence state incorporation in augmenting osteoblast differentiation.Collectively, this dissertation contributes expanding the field of biomaterials by elucidating the dual utility of rare-earth doped hydroxyapatite scaffolds in promoting osteogenic differentiation and providing luminescence-based insights into scaffold behavior in physiological environments. By combining the luminescence stability studies with the exploration of osteogenic potential, our research underscores the importance of integrating multifunctional elements into scaffold design to enhance their performance in bone tissue engineering. The insights garnered from both studies not only pave the way for the development of novel biomaterials but also highlight the potential of rare-earth elements as pivotal components in the advancement of regenerative medicine and biomedical engineering.

V sklopu magistrske naloge sem sprva sintetiziral spojini [Zn(I3P)2] in [Zn(I3O)2]. Pri sintezi obeh navedenih spojin sem kot izhodno spojino uporabil ZnCl2 in ustrezno kislino (indol-3-propanojsko (I3P-H) in indol-3-ocetne kislino (I3O-H)). Pripravljeni spojini sem nato uporabil kot izhodni spojini pri sintezah z različnimi nevtralnimi dušikovimi ligandi. Sinteze sem izvajal v dveh množinskih razmerjih med izhodno spojino cinka in ligandom (1:1 in 1:2), ob uporabi različnih topil (metanol, etanol, kloroform, voda, aceton, dimetilformamid) v različnih kombinacijah. Nastale produkte sem okarakteriziral z analizo razultatov nekaterih fizikalno-kemijskih metod (rentgensko praškovna analiza (PXRD), rentgenska analiza monokristala (XRD), jedrska magnetna resonanca (1 H NMR). Posnel sem tudi IR spektre, UV-Vis in luminiscenčne spektre produktov v trdnem. Z uporabo navedenih metod sem predvidel sledeče formule dobljenih spojin: [Zn(I3P)2(2,2'-bipy)] (2,2'-bipy = 2,2'-bipiridin), [Zn(I3O)2(4,4'-bipy)], [Zn(I3P)2(4,4'-bipy)] (4,4'-bipy = 4,4'-bipiridin), [Zn(I3O)2(4-ampy)2]∙H2O (4 ampy = 4-aminopiridin), [Zn(I3P)2(bipyam)] (bipyam = 2,2'-bipiridilamin), [Zn(I3P)2(phen)] (phen = 1,10-fenantrolin), [Zn(I3P)2(neo)], [Zn(I3O)2(neo)] (neo = neokuproin). As a part of my master thesis [Zn(I3P)2] and [Zn(I3O)2] were initially synthesized from ZnCl2 and the corresponding acid (indole-3-propanoic and indole-3-acetic acid). Those two compounds were used as starting compounds in syntheses with various neutral nitrogen ligands. Syntheses were performed in two mass ratios between the initial zinc compound and the ligand (1:1 and 1:2), using different solvents (methanol, ethanol, chloroform, water, acetone, dimethylformamide) in different combinations. The resulting products were characterized by analyzing the results of some methods (X-ray powder analysis (PXRD), single crystal X-ray analysis (XRD), nuclear magnetic resonance (1H NMR). IR spectra, UV-Vis and luminescence spectra of the products were recorded in the solid state. Following formulas of the obtained compounds were predicted: [Zn(I3P)2(2,2'-bipy)] (2,2'-bipy = 2,2'-bipyridine), [Zn(I3O)2(4,4'-bipy)], [Zn(I3P)2(4,4'-bipy)] (4,4'-bipy = 4,4'-bipyridine), [Zn(I3O)2(4-ampy)2]∙H2O (4 ampy = 4-aminopyridine), [Zn(I3P)2(bipyam)] (bipyam = 2,2'-dipyridylamine), [Zn(I3P)2(phen)] (phen = 1,10-phenanthroline), [Zn(I3P)2(neo)], [Zn(I3O)2(neo)] (neo = neocuproine).

346 p. (eng.) 246 p. (eusk.) En esta tesis se desarrollan y estudian materiales híbridos zeotípicos fotoactivos para la obtención de sistemas multifuncionales en estado sólido con interesantes propiedades ópticas aptas para aplicaciones en el campo de la fotónica. Para ello, se atrapan colorantes orgánicos en nanocavidades restringidas de estructuras inorgánicas de aluminofosfato dopadas con metales (con Si o Mg, obteniendo estructuras tipo SAPO y MgAPO, respectivamente) para promover procesos fotofísicos nuevos y/o mejorados en los materiales por efecto sinérgico, en comparación con los fluoróforos aislados.En este trabajo se preparan un gran número de materiales de colorante-AlPO, combinando varias estructuras con diferentes formas y tamaños de poros/canales en el rango de dimensiones moleculares, con una amplia gama de colorantes orgánicos, principalmente de las familias de estirilos y aromáticos fusionados de tres anillos. La inclusión de fluoróforos en las cavidades de los AlPOs realizada "in situ" por el método de inclusión por cristalización permite el desarrollo directo de materiales híbridos fluorescentes con funcionalidades ópticas destacadas y específicas en un solo paso y en cortos periodos de tiempo, describiendo así una síntesis rentable y eficiente para sistemas avanzados.Por un lado, como resultado de la sinergia entre moléculas fotoactivas push-pull con anfitriones de aluminofosfato canalizados en 1D (AFI, ATS y AEL) y una estructura de tipo jaula-3D (CHA), se obtienen sistemas sólidos ópticamente densos con capacidad de fluorescencia mejorada y respuesta altamente anisotrópica a la luz linealmente polarizada. A través de esta estrategia las aplicaciones logradas son diversas, desde emisores NIR hasta generadores de segundo armónico y láseres en estado sólido a nivel de partícula.Por otro lado, la oclusión simultánea de diferentes especies fotoactivas en los aluminofosfatos (IFO y AEL) promueve la probabilidad de procesos de FRET en cascada entre moléculas orgánicas ocluidas en el espacio restringido de los canales zeotípicos. La coencapsulación de especies adecuadas y racionalmente seleccionadas (pares FRET) proporciones idóneas conduce a nuevos sistemas de antenas artificiales, con propiedades como la emisión sintonizable y la emisión de luz blanca.A lo largo de este trabajo, las síntesis de los materiales híbridos dopados con colorantes se optimizan (variando la composición del gel, la temperatura y el tiempo y método de calentamiento) y la morfología y cristalización de todas las fases presentadas se comprueban mediante técnicas de SEM y difracción de rayos-X en polvo. Las propiedades fotofísicas de los materiales híbridos y de los colorantes fotoactivos se analizan en profundidad mediante técnicas de estado estacionario y resueltas en el tiempo (espectroscopias de absorción y emisión), así como mediante microscopía de fluorescencia, que permite el análisis a nivel de partícula. Además, se demuestra la aplicabilidad final de los materiales mediante técnicas sofisticadas como la detección de señales de generación de segundos armónicos y la respuesta de acción del microláser

Mūsdienās fluorescentas metodes ir plaši izmantotas vairākās zinātnes un medicīnas nozarēs: luminiscējošie materiāli ir nozīmīgi imunoķīmijā, in situ hibridizācijas fluorescencē, šūnu pētījumos, citoķīmijā, medicīniskos izmeklējumos un citur. Fluorescentā iekrāsošana ir process, kura gaitā notiek fluorofora kovalentā pievienošana pētāmai molekulai. Tagad ir izpētītas vairākās luminiscentas iezīmes olbaltumvielu, lipīdu un nukleīnskābju vizualizēšanai. Proteīnu vizualizācijai bioķīmiķi un biologi plaši izmanto luminiscentu iezīmi FITC, kura līdzīgi projektā pielietotam marķierim satur izotiocianāta grupējumu, kas spēj reaģēt ar aminogrupām un tādā veidā iezīmēt biomateriālu, kurā ir aminogrupas (amiboskābes, olbaltumvielas u.c.).

В данной работе рассмотрены основные свойства нанокристаллического порошка вольфрамата лютеция, а также особенности люминесценции при легировании порошка ионами редкоземельного металла европия. Были изучены основные методики синтеза Ð½Ð°Ð½Ð¾ÐºÑ€Ð¸ÑÑ‚Ð°Ð»Ð»Ð¸Ñ‡ÐµÑÐºÐ¸Ñ Ð¿Ð¾Ñ€Ð¾ÑˆÐºÐ¾Ð², золь-гель методом (Печини) получена концентрационная серия образцов с 1, 2, 5, 10, 15 и 20 мол. % ионов европия. Синтезированные порошки были исследованы методами рентгенофазового анализа, сканирующей электронной микроскопией и люминесцентного анализа., In the given work the characteristics of the nanocrystalline lutetium tungstate powder, as well as the features of luminescence when the powder is doped with rare-earth metal ions, europium. The main methods for the synthesis of nanocrystalline powders were reviewed, and a concentration series with 1, 2, 5, 10, 15, and 20 mol. % europium ions. Then the resulting powder was examined by X-ray phase analysis, scanning electron microscopy and luminescent analysis.Â

Cietvielu luminoforu molekulārais dizains. Mazarevičs A., zinātniskie vadītāji Mg. chem. Leduskrasts K., Prof., Dr. chem. Sūna E. Maģistra darbs, 72 lapaspuses, 44 attēli, 11 tabulas, 38 literatūrās avoti, 1 pielikums. Latviešu valodā. Literatūras apskatā analizēti organiskie luminofori, luminiscence un fosforescence. Iekļauti organiskās fosforescences iegūšanas metožu piemēri izmantojot starpmolekulāru mijiedarbību veidošanu, smagā atoma efektu, kā arī heteroatomu ievadīšanu molekulā. Rezultātu izvērtējumā aprakstīta sintezēto savienojumu iegūšana un analizētas to luminiscentās īpašības. Eksperimentālajā daļā sintezēti 26 savienojumi, no kuriem luminiscentās īpašības noteiktas 13. No luminiscentajiem savienojumiem, četri satur arilgredzenu piektajā pozīcijā tiofēna ciklā, trīs alkilķēdes tiofēna ciklā ceturtajā un piektajā pozīcijā, trīs satur karbazola grupu tiofēna cikla trešajā pozīcijā un karbonilfragmentu otrajā pozīcijā, bet trīs – benzo[b]tiofēnu, kā arī karbazola un karbonilfragmentu attiecīgi trešajā un otrajā tiofēna cikla pozīcijā. Eksperimentālajā daļā ir apskatītas sintēžu metodes, kā arī doti vielu raksturojumi, izmantojot 1H KMR, 13C KMR, IS un EA analīzes metodes., Molecular design of solid state luminophores. Mazarevics A., supervisors M.Sc. chem. Leduskrasts K., Prof., Dr. chem Suna E. Master’s thesis, 72 pages, 44 figures, 11 tables, 38 references, 1 appendix. In Latvian. In a literature review organic luminophores, luminescence and methodologies that allow to achieve phosphorescence were analysed. Analysis consisted of such methodologies as intermolecular interaction control, heavy atom effect and the introduction of heteroatoms with a lone electron pair for achieving phosphorescence. The results section describes the compound synthesis and their luminescent property analysis. In the experimental part 26 compounds were synthesized and the luminescent properties of 13 were measured. From the studied luminescent compounds four contain an aryl substituent in the 5th position of the thiophene ring, three contain an alkyl substituent in the 4th and 5th position of the thiophene ring, three contain carbazole in the 3rd and carbonyl substituents in the 2nd position of the thiophene ring, and three contain a benzo[b]thiophene heterocycle, where a carbazole moiety is connected in the 3rd position and a carbonyl substituent in the 2nd position. The experimental part describes the methods of synthesis and characterizes the synthesized compounds using 1H and 13C nuclear magnetic resonance, infrared spectroscopy, and elemental analysis.

Luminiscējoši materiāli tiek plaši pielietoti gan ikdienišķiem, gan zinātniskiem mērķiem. Pēdējos gados pieaugusi interese par sarkaniem un infrasarkaniem ilgspīdētājiem īpaši tādēļ, ka tiem ir potenciāli pielietojumi medicīnā. Šajā darbā pētīta sarkanā un infrasarkanā luminiscence MgGeO3:Mn2+, Cr3+ materiālā. Darba gaitā paraugiem uzņemti ierosmes, fotoluminiscences, rentgenluminiscences un pēcspīdēšanas spektri, mērīta dzišanas kinētika un veikti termostimulētās luminiscences mērījumi. MgGeO3:Mn2+, Cr3+ materiālam raksturīga luminiscence platā spektra joslā no 600 līdz 1000 nm un novērojama efektīva pēcspīdēšana, kuru nodrošina ķērājcentri ar dziļumu 1.18 -1.36 eV. Balstoties uz iegūtajiem rezultātiem, veikti secinājumi par MgGeO3:Mn2+, Cr3+ materiāla luminiscences īpašībām un pēcspīdēšanas gaitā notiekošajiem procesiem., Luminescent materials are widely used for domestic and scientifical purposes. In recent years red and infrared persistent luminescence has been studied for applications in medicine. During this research red and infrared luminescence of MgGeO3: Mn2+, Cr3+ material was investigated. During this research the excitation, photoluminescence, x-ray luminescence and afterglow spectra were taken, the decay kinetics and thermal stimulated luminescence were measured. MgGeO3: Mn2+, Cr3+ material shows luminescence in broad spectral range from 600 to 1000 nm and exhibit intense afterglow which is provided by charge traps with depth about 1.18 – 1.36 eV. Based on obtained results conclusions about MgGeO3: Mn2+, Cr3+ material luminescence properties and afterglow mechanisms has been drawn.

Mūsdienās pārejas metālu pētniecība, pielietojot tos kā aktivatorus platzonu materiālos, ir nozīmīga. Tiek atklāti jauni veidi, kā var uzlabot materiālu struktūras vai luminiscences īpašības, neizmantojot retzemju elementus. Kā perspektīvu luminoforu ar maināmu luminiscences krāsu varētu lietot ar Mn2+ un Mn4+ joniem aktivētu CaAl4O7. Tas ir lēts, pieejams un viegli sintezējams. Darbā tiek sintezēti ar mangāna joniem aktivēti kalcija alumināta paraugi pie dažādām Mn koncentrācijām no 0.2 mol% līdz 4 mol%, izmantojot cietfāžu sintēzes metodi. Ir novērotas Mn2+ un Mn4+ jonu emisijas pārejas, ierosinot tās ar 330 nm un 406 nm viļņa garumu, ar luminiscenci diapazonos attiecīgi 500-650 nm un 640-720 nm. Paraugiem tika veikti XRD, EPR, luminiscences un luminiscences dzišanas kinētikas mērījumi. Rezultāti liecina par Mn2+ iebūvēšanos CaAl4O7 struktūrā vienā režģa pozīcijā. Maksimālā Mn2+ jonu luminiscences intensitāte novērota paraugam ar koncentrāciju 1 mol% Mn., Research into transition metals has become highly important in recent times with their increasing use as activators in wide band-gap materials. New ways of improving the structural or luminescent properties of materials without the use of rare-earth elements are being discovered. A perspective phosphor with tuneable luminescence colour is manganese ion (Mn2+ and Mn4+) activated calcium aluminate (CaAl4O7) which is inexpensive and easy to synthesize. In the present work, CaAl4O7:Mn2+/Mn4+ is synthesized for various Mn doping concentrations between 0.2 mol% and 4 mol% using solid-phase synthesis. Mn2+ and Mn4+ emission transitions are observed when excited with 330 nm and 406 nm wavelength light, with luminescence occuring at wavelengths of 500-650 nm and 640-720 nm respectivelly. XRD, EPR, photoluminescence (PL) and PL decay kinetics measurements have been conducted on the samples. The results show the incorporation of Mn2+ in one position of the CaAl4O7 lattice. The maximum luminescence intensity of Mn2+ ions was observed for the sample with dopant concentration of 1 mol% Mn.

Luminiscenti materiāli tiek plaši izmantoti dažādu sensoru un optisko ierīču izgatavošanā. Lai izvērtētu luminoforu piemērotību konkrētiem pielietojumiem, ir nepieciešams apjaust tajos notiekošos luminiscences procesus. Šī maģistra darba ietvaros tika pētīti ar mangānu, eiropiju un hromu aktivētu alumīnija nitrīda (AlN) materiālu luminiscences mehānismi. Tika veikti materiālu rentgendifrakcijas, kā arī luminiscences, tās ierosmes un kinētiku mērījumi. No pētītajām vielām ar visintensīvāko aktivātora luminiscenci izcēlās AlN:Mn. Tam tika novērota arī ilga luminiscence pēc ierosinājuma pārtraukšanas – ilgspīde. Šī darba rezultāti var tikt tālāk izmantoti jaunu luminiscentu materiālu un ierīču izstrādei., Luminescent materials are commonly used in the production of sensors and optical devices. Understanding the luminescence processes that occur in phosphors is required to assess their suitability for specific applications. In the context of this master’s thesis, luminescence mechanisms of manganese, europium, and chromium-doped aluminum nitride (AlN) materials were investigated. The materials were studied using X-ray diffraction, as well as measurements of luminescence, its excitation, and kinetics. AlN:Mn had the most intense luminescence of the activator among the substances studied. It also demonstrated a long-lasting luminescence. The findings of this thesis can be used to create new luminescent materials and devices.

Eiropija jons ir viens no retajiem lantanoīdiem, kurš materiālā vienlaikus spēj atrasties divalentā un trīsvalentā formā. Katram jonam piemīt atšķirīgas luminiscences īpašības, kuras ietekmē arī matricas izvēle un sintēzes process, tādā veidā ir iespējams pagatavot aktivētu materiālu, kura emisija ir specifiski pielāgota vēlamajam mērķim. Eiropijs jau tiek izmantots lāzeros, gaismu emitējošās diodēs, plazmas paneļos, rentgenstaru detektoros, par matricām kalpojot oksifluorīdu un fosfātu stikliem, keramikām un kristalītiem. Pētījuma mērķis ir veiksmīga ar eiropija joniem aktivētu kalcija fluorīda kristalītu sintēze un to luminiscences īpašību novērošana un raksturošana. Tika pagatavoti paraugi ar 7 dažādām Eu koncentrācijām un izkarsēti 6 dažādās temperatūrās. Tika novēroti Eu2+ un Eu3+ raksturīgās pārejas emisijas, ierosmes un absorbcijas spektros un salīdzināta to relatīvā intensitāte, kā arī atkarība no Eu koncentrācijas paraugā un pēcapstrādes temperatūras. Tāpat tika veikti arī XRD un SEM mērījumi paraugu kvalitatīvai raksturošanai. Tika secināts, ka pie augstām temperatūrām notiek Eu3+ reducēšanās un palielinās Eu2+ klātbūtne un līdz ar to izteikta emisijas intensitātes palielināšanās 400−450 nm apgabalā. Darbs rakstīts latviešu valodā un satur 40 lapas un 23 attēlus., Europium ions can be found in host lattice in both its divalent and trivalent forms, each with their own characteristic luminescence that is dependent on the choice of host lattice and synthesis. Hence, a fine tuned emission material can be obtained to suit any specific needs. Europium has already been used and studied wildly for its properties and availability. The aim of this research is a successful synthesis of europium doped calcium fluoride crystallites and to observe and identify its luminescence properties. Samples with 7 different concentrations of Eu were prepared and thermally treated in 6 different temperatures. The characteristic transitions of Eu2+ and Eu3+ were observed in emission, excitation and absorption spectra, and comparisons between their relative intensities were made, as well as investigated dependence on the concentration of Eu and post-processing temperature. Furthermore XRD measurements and SEM imaging were made for qualitative analysis. It was concluded that at high temperatures, Eu3+ reduction takes place and thus increased the presence of Eu2+ and its emission intensity in the 400 − 450 nm region. The thesis is written in Latvian and contains 40 pages and 23 images.

beta-Si6-zAlzOzN8-z is a prominent example of systems suitable as hosts for creating materials for light-emitting diodes (LEDs). In this work, the electronic structure of a series of semiordered and disordered beta-Si6-zAlzOzN8-z systems is investigated by means of ab initio calculations, using the FLAPW and Green function KKR methods. Finite temperature effects are included by averaging over thermodynamic configurations within the alloy analogy model. We found that the dependence of the electronic structure on the (Al,O) concentration z is similar for semiordered and disordered structures. The electronic band gap decreases with increasing z by about 1.5 eV when going from z=0 to z=2. States at the top of the valence band are mostly associated with N atoms whereas the states at the bottom of the conduction band are mostly derived from O atoms. Increasing the temperature leads to a shift of the bottom of the conduction band to lower energies. The amount of this shift increases with increasing z.

Metāla nanodaļiņas var uzlabot organiskā pusvadītāja luminiscenci, tāpēc tas var palīdzēt attīstīt - laboratorijas mikroshēmas, sensorus vai gaismas modulatorus, kas ir balstīti uz organisko pusvadītāju bāzes. Šajā darbā tika veikta sfērisku un prizmatisku “core-shell” sudraba nanodaļiņu sintēze ūdens vidē un ar dažādām metodēm tika īstenota to pārnese organiskajos šķīdinātājos. Tika izmantota ultraskaņas metode un nanodaļiņas pārnese heksānā. Pēc pārneses sudraba nanodaļiņas tika jauktas ar organisko luminoforu DWK-1-TB. Darbā tika pētītas nanodaļiņu-organiskā luminofora sistēmas luminiscences īpašības. Tika apskatīts kā nanodaļiņas ietekmē luminofora kvantu iznākumu, fotonu dzīves laiku, emisijas kartes plānās kārtiņās un šķīdumos., Metal nanoparticles can enhance organic semiconductor luminescence, so it can help to develop laboratory chips, sensors or light modulators based on organic semiconductors. In this work, the synthesis of spherical and prismatic “core-shell” silver nanoparticles was performed in the aquatic environment and their transfer in organic solvents was carried out by various methods. Ultrasound and nanoparticle transfer in hexane were used. After transfer, the silver nanoparticles were mixed with the organic luminophore DWK-1-TB. In this work luminescence property of nanoparticle-organic luminophore system were studied and viewed how nanoparticles affect luminophore quantum yield, photon lifetime, emission maps in thin films and solutions.

[Resumen] Pseudomonas aeruginosa constituye un factor de riesgo para los seres humanos, al considerarse una de las bacterias responsables de gran parte de las infecciones que los enfermos adquieren en los hospitales, provocando en algunos casos efectos muy perjudiciales en la salud del paciente. En este trabajo se ha desarrollado un sensor para detectar y monitorizar el enzima Elastasa B, un enzima que la bacteria Pseudomonas aeruginosa segrega al medio celular, y que por tanto permitiría detectar la bacteria. El sensor está formado por un complejo macrocíclico de Tb(III) luminiscente unido a un péptido que contiene la secuencia consenso que corta el enzima. La síntesis del péptido se ha llevado a cabo mediante síntesis manual en fase sólida, mientras que el macrociclo es un derivado del DO3A. El funcionamiento de la sonda se basa en que la antena necesaria para transferir la energía al Tb(III), y que se produzca la emisión de luminiscencia por parte del metal, se encuentra separada del complejo metálico por la secuencia de reconocimiento del enzima, de tal modo que la ruptura de la secuencia peptídica por parte del enzima conlleva a una disminución de la luminiscencia. [Abstract] Pseudomonas aeruginosa constitutes a risk for humans, as it is considered one of the bacteria responsible for a large part of the hospital infections, in some cases causing very harmful effects on the patient’s health. In this work, a sensor has been developed to detect and monitor the enzyme Elastase B, an enzyme secreted by Pseudomonas aeruginosa into the cellular environment, that would therefore allow the detection of the bacterium. The sensor consists of a luminescent Tb(III) macrocyclic complex linked to a peptide containing the consensus sequence that cleaves the enzyme. The synthesis of the peptide has been carried out by manual solid-phase synthesis, while the macrocycle is a derivative of DO3A. The sensing mechanism of the probe relies on the fact that the antenna necessary to transfer the energy to the Tb (III) ion, and for the luminescence emission of the metal, is separated from the metal complex by the enzyme binding sequence, so that the cleavage of the peptide sequence by the enzyme leads to a decrease in luminescence. [Resumo] Pseudomonas aeruginosa constitue un risco para os seres humanos, ó considerarse unha das bacterias responsables de gran parte das infeccións que os enfermos adquiren nos hospitais, provocando nalgúns casos efectos moi perxudiciais para a saude do paciente. Neste traballo desarrollouse un sensor para detectar e monitorizar o enzima Elastasa B, un enzima que a bacteria Pseudomonas aeruginosa segrega ao medio celular, e que polo tanto permitiría detectar a bacteria. O sensor está formado por un complexo macrocíclico de Tb(III) luminiscente unido a un péptido que contén a secuencia consenso que corta o enzima. A síntesis do péptido levóuse a cabo mediante síntesis manual en fase sólida, mentres que o macrociclo é un derivado do DO3A. O funcionamento da sonda básase en que a antena necesaria para transferir a enerxía ao Tb(III) e que se produza a emisión de luminiscencia por parte do metal, encóntrase separada do complexo metálico pola secuencia de reconoñecento do enzima, de tal modo que a ruptura da secuencia peptídica por parte do enzima provoca unha disminución da luminiscencia. Traballo fin de grao (UDC.CIE). Química. Curso 2021/2022

Six new uranyl hybrid materials have been synthesized solvothermally utilizing the ligands 2,2′-bipyridine-3,3′-dicarboxylic acid (H2L) and 2,2′:6′,2′′-terpyridine (TPY). The six compounds are classified as either molecular complexes (I0O0 connectivity), [(UO2)(L)(TPY)]·H2O (1), [Ni(TPY)2][(UO2)(L)2]·3H2O (2), and [Cu(TPY)2][(UO2)(L)2]·3H2O (3), or 3D metal–organic frameworks (MOFs, I0O3 connectivity), [Cu2(UO2)2(OH)(C2H3O2)(L)3(TPY)2]·6H2O (4), [Zn2(UO2)2(OH)(NO3)(C2H3O2)(L)3(TPY)2]·4H2O (5), and Na[Ni(UO2)3(OH)(O)(L)3]·9H2O (6). A discussion of the influence of transition metal incorporation, chelating effects of the ligand, and synthesis conditions on the formation of uranyl materials is presented. The structure of compound 6 is of particular note due to large channel-like voids with a diameter of approximately 19.6 Å. A topological analysis of 6 reveals a new topology with a 9-nodal 3,3,3,3,3,3,3,4,5-connected network, designated geg1 hereafter. Further, solid state photoluminescence experiments show emission and lifetimes values consistent with related uranyl compounds. Fil: Gomez, Germán Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina Fil: Ridenour, J. August. The George Washington University; Estados Unidos Fil: Byrne, Nicole M.. The George Washington University; Estados Unidos Fil: Shevchenko, Alexander P.. Samara University; Rusia Fil: Cahill, Christopher L.. The George Washington University; Estados Unidos

Down conversion (DC) in rare-earth-doped optical materials is a process of great interest for the possibility of a substantial increase of the efficiency of silicon solar cells. Here we report the structural and photoluminescence properties of co-doped CaF2 phosphors obtained by hydrothermal synthesis. In particular, the DC photoluminescence characteristics for UV (353 nm) excitation of Nd3+/Yb3+ co-doped CaF2 phosphors are discussed, underlining the effects due to the co-doping with Li+. The photoluminescence emission is dominated by the near-infrared (NIR) Yb3+ emission peaked at 975 nm, although the excitation spectrum corresponds to the characteristic peaks associated with Nd3+ excitation at both the UV and visible wavelength ranges. The Nd3+ to Yb3+ energy transfer mechanisms were determined from a detailed analysis of the excitation spectra characteristics of Nd3+ and Nd3+/Yb3+/Li + doped CaF2 phosphors. DC photoluminescence for UV excitation was confirmed by both the analysis of DC quantum yield efficiency and effective quantum yield measurements. In the first case, an efficiency up to 150% was found, while the effective quantum yield measurements, carried out for the UV (DC) and visible (downshift) excitation and NIR photoluminescence emission, give values of 81 ± 10% and 37 ± 5% for excitation with 353 nm and 577 nm light, respectively.

Title: Development of novel photoactive cationic zirconocene complexes Author: Bc. David Dunlop Department: Department of inorganic chemistry Supervisor: RNDr. Martin Lamač Ph.D. Advisor: prof. RNDr. Petr Štěpnička, Ph.D., DSc. Abstract: Environmental concerns have brought about an unprecedented demand for sustainable energy sources among which electromagnetic radiation, light, currently dominates. Development of novel light- harvesting compounds and materials is at the forefront of current science, as it is essential to further our technological progress. This thesis contributes to the field by development of novel photoactive cationic group 4 metallocene complexes stabilized by pendant imine and pyridinyl donor groups, or N,O-donor aromatic ligands, as crystalline [B(C6F5)4]− salts. The complexes are prepared either by protonation of the intramolecularly bound imine moiety by PhNMe2H[B(C6F5)4] or by chloride ligand abstraction, by Li[B(C6F5)4]·2.5Et2O or in situ generated Et3Si[B(C6F5)4]. Prepared compounds were characterized by NMR spectroscopy. Solid state structures of the compounds were determined by X-ray diffraction analysis. The cationic complexes of Zr and Hf exhibited significantly enhanced luminescence which originates from triplet ligand-to-metal (3 LMCT) excited states with lifetimes of up to...

LU Studentu zinātnisko rakstu krājums “Mundus et” ir Latvijas Universitātes Studentu padomes organizētās LU Studentu zinātniskās konferences “Mundus et” jauno pētnieku darbu apkopojums.

V delu smo izvedli meritve in numerično obdelavo nestacionarnega temperaturnega polja na submikronski skali. Električno greto konico smo postavili na dopirano steklo Er:GPF1Yb0.5Er. Zaradi spremembe v temperaturi je prišlo do pojava fluorescence, ki smo jo z mikroskopom zaznali in naredili posnetke nestacionarnih temperaturnih polj. Z namenom zmanjšanja šuma in izostritve slike nestacionarnega temperaturnega polja smo izdelali programsko orodje v programu Matlab. Pridobljene rezultate smo primerjali z originalnimi slikami nestacionarnega temperaturnega polja in jih ovrednotili. S tem smo pomembno izboljšali kakovost slike nestacionarnega temperaturnega polja. Thesis consist of measurements and numerical processing of transient temperature field on submicron scale. Electric heated tip was mounted on doped glass Er:GPF1Yb0.5Er. Due to temperature change, fluorescence phenomena was detected with a microscope. Pictures of temperature field were then taken. In order to decrease noise ratio and increase image sharpening, a software program was created in Matlab. Results were compared with original picture of transient temperature field, further on results were evaluated. This significantly improved quality of pictures of transient temperature field.

Four new thiocyanate-Zn(II) and -Cd(II) complexes with 1-methylimidazole (1-MeIm) and 2-methylimidazole (2-MeIm), namely, Zn(1-MeIm)2(SCN)2 (1), Zn(2-MeIm)2(SCN)2 (2), Cd(1-MeIm)4(SCN)2 (3) and polymeric [Cd(2-MeIm)2(SCN)2]n (4), have been synthesized and characterized by IR, Raman and UV-Vis spectroscopy. The thermal behavior for all complexes was evaluated by thermo-gravimetric analysis and differential thermal analysis. The crystal structures of complexes 1–4 were solved by single-crystal X-ray diffraction methods. A study of intermolecular interactions in the solid state compounds revealed that molecules are linked by weak N–H⋯S and C–H⋯S hydrogen bonds and also by C–H⋯π interaction in the case of structures 2–4, which are responsible for the formation and stability of the molecular assemblies. Hirshfeld surfaces and 2D-fingerprint plots allowed us to visualize the intermolecular contacts and their relative contributions to the total surface for each compound. A comparative analysis against similar halogen-bonded complexes was carried out to investigate the tendency of inter-molecular interactions to form contacts in crystals by using the enrichment ratio descriptor. The emission spectra of the free imidazole derivatives and their Zn(II) and Cd(II) complexes were recorded in acetonitrile solutions. The emissions observed in the spectra of complexes were ascribed to the intra-ligand transitions and ligand-to-metal charge transfer and we have observed an interesting correlation between the fluorescence intensities and C–H⋯π interactions., Instituto de Física La Plata

Ideally, any material used should be nontoxic and produced with safe, inexpensive, and energy‐effective processes. In the case of optically active nanoparticles, this is often not the case, as they are frequently composed of hazardous heavy metals and/or produced with methods far from being environmentally friendly. Herein, the preparation of Ag2S‐based nanoparticles via a simple green synthesis route is explored. Aqueous extracts of roasted coffee are used as sources of coordinating molecules. Optimization of the reaction conditions yields dimeric Ag−Ag2S nanoparticles, whose near‐infrared photoluminescence can be switched on via H2O2‐mediated oxidation. This oxidation transforms suitable photoacoustic contrast agents into fluorescence imaging probes. Theoretical calculations further clarify the role of metallic silver in determining the optical properties of Ag2S. Overall, it is demonstrated that nanomaterials with tangible applicative potential can be prepared via cost‐ and energy‐effective synthesis strategies that entail benign, renewable chemicals.

Eiropija jonu un sudraba nanodaļiņu pētniecība oksifluorīda stikla keramikā ir aktuāla mūsdienu zinātnes joma. Pēdējos gados tiek atklāti jauni veidi, kā var uzlabot luminiscences īpašības vai materiālu struktūras, lai tās varētu pielietot sadzīves elektronikā vai optiskajās ierīcēs. Kā perspektīvu sarkanās gaismas luminoforu varētu lietot ar eiropija joniem aktivētu stikla keramiku. Sudraba nanodaļiņām piemīt īpašība pastiprināt vai samazināt stikla keramikas un retzemju jonu luminiscences intensitāti. Literatūras aprastā tiek apskatīta retzemju jonu, stikla keramikas un sudraba nanodaļiņu luminiscence un tās pamatprincipi, kā arī struktūras un kristalītu veidošanās stiklā un stikla keramikā. Arī tiek apskatīti piemēri, kā veidojas un mainās izmēri sudraba nanodaļiņām oksifluorīdu stikla keramikā. Praktiskajā daļā tiek izgatavoti dažādi stiklu un stikla keramikas paraugi ar Eu3+ un Ag+ joniem. Ir novērotas trīsvērtīgā eiropija emisijas pārejas. Ir nomērīti luminiscences spektri, ierosinot tos ar 275 nm 350 nm un 320 nm viļņa garuma. Atsevišķiem paraugiem tika veiktas absorbcijas, XRD un EPR mērījumi. Tika secināts, ka sudraba nanodaļiņas ir izveidojušās un tās spēcīgi absorbē ierosinošo starojumu 350 nm – 450 nm diapazonā., Studies of europium ions and silver nanoparticles in oxyfluoride glass ceramic materials is an attractive research field recently. In the last years, new methods on how to improve properties of photoluminescence and material structure, are being found in order to apply them in electronic or optical devices. Glass ceramics activated with europium ions could be used as a perspective lighting source. Silver nanoparticles are able to improve or decrease the photoluminescence intensity of rare arth ions in glass ceramics. In the literature review, the luminescence of rare earth ions., glass ceramics and silver nanoparticles and their properties are described. Examples, how size of silver nanoparticles in oxyfluoride glass ceramics changes, are described. In the experimental part, series of glass and glass ceramics with Eu3+ and Ag+ ions were synthesized. The emission bands of Eu3+ ions were observed. The luyminescence spectra were measured with 275 nm. 350 nm, 320 nm excitation. XRD, EPR and absorption spectra of some samples were measured. It was concluded that silver nanoparticles were formed and they stronlgy absorb 350 – 450 nm radiation.

Darbā tika pētītas Gd3Ga3Al2O12:Ce un ar divvērtīgajiem (Mg2+, Ca2+) un četrvērtīgajiem (Zr4+, Ti4+) metālu joniem koaktivēto Gd3Ga3Al2O12:Ce absorbcijas un luminiscences īpašības, ka arī tika izmērītas luminiscences dzišanas kinētikas un to temperatūras atkarības. Darbā tika piedāvāti Gd3Ga3Al2O12:Ce luminiscences mehānismi pētāmajos ierosinājumos., Absorption and luminescence properties of Gd3Ga3Al2O12:Ce and co-doped with divalent (Mg2+, Ca2+) and tetravalent (Zr4+, Ti4+) ions Gd3Ga3Al2O12:Ce crystals have been studied as well as time-resolved luminescence and its temperature dependence. In this study luminescence mechanisms of Gd3Ga3Al2O12:Ce have been proposed.

Darba gaitā tika sintezēti 10 dažādi MgGeO3:Mn2+ paraugi ar atšķirīgām divvērtīga mangāna jonu koncentrācijām: 0 mol%, 0.1 mol%, 0.25mol%, 0.5 mol%, 0.75 mol%, 1 mol%, 1.5 mol%, 2 mol%, 5 mol% un 10 mol%. Paraugiem novērojam luminiscence sarkanajā un infrasarkanajā spektra daļā, un tos iespējams ierosināt ar ultravioleto starojumu un rentgena starojumu. Ierosinot paraugus ar rentgena starojumu, detektējama pēcspīdēšana ilgāk par 10 stundām. Paraugiem mērīta rentgenstaru difrakcija, elektronu paramagnētiskā rezonanse, ierosmes spektri, luminiscences spektri, pēcspīdēšanas spektri, dzišanas kinētikas un termostimulētā luminiscence. Balstoties uz iegūtajiem rezultātiem, tika spriests par MgGeO3:Mn2+ materiālā notiekošajiem luminiscences procesiem un Mn2+ jonu koncentrācijas ietekmi uz tiem., In the course of this study MgGeO3:Mn2+ samples with Mn2+ concentration of 0 mol%, 0.1 mol%, 0.25 mol%, 0.5 mol%, 0.75 mol%, 1 mol%, 1.5 mol%, 2 mol%, 5 mol% and 10 mol% were prepared. Samples excited by UV and X-rays exhibit intense red and infrared luminescence. After excitation by X-ray radiation samples continue to glow longer than 10 hours. During the research the X-ray diffraction, electron paramagnetic resonance, excitation, luminescene emission and the decay kinetics and afterglow were measured and thermally stimulated luminescence spectra were taken. Based on obtained results, conclusions about luminescence process and role of concentration of Mn2+ in the MgGeO3:Mn2+ material has been drawn.

Caurspīdīga stikla keramika ir kompozītmateriāls, kurā amorfā stikla fāzē atrodas izkliedēti nanokristāli. Tā kā caurspīdīgām stikla keramikām ir vairāki iespējamie pielietojumi fotonikā, svarīgi ir novērtēt aktivatoru jonu iebūvēšanos kristāliskajā fāzē nanokristālos, kā arī raksturot optiskās īpašības kvantitatīvi. Darba gaitā sintezēti stikla keramikas paraugi, kas satur CaF2 kristālisko fāzi, ar Eu3+ koncentrāciju 0.5, 1, 1.5, 2, 5 un 10 mol%. Paraugiem veikti rentgendifrakcijas mērījumi, no kuriem iespējams novērtēt aktivatoru jonu iebūvēšanās efektivitāti, izmantojot kristāliskā režģa konstantes izmaiņas atkarībā no Eu3+ koncentrācijas. Veicot luminiscences ierosmes spektru mērījumus spektrālajā apgabalā no 420 nm līdz 530 nm, tika novērotas Eu3+ raksturīgās luminiscences joslas. Noteikts, ka luminiscences intensitāte stikla keramikā pieaug, palielinot trīsvērtīgā eiropija jonu koncentrāciju. Selektīvās ierosmes spektroskopija ļauj noteikt, cik dažādās kristāliskajās pozīcijās stikla keramikā atrodas eiropija joni. Paraugiem ir veikts luminiscences kvantu efektivitātes novērtējums, un noteikta tā atkarība no stikla keramikas karsēšanas temperatūras, kā arī Eu3+ koncentrācijas., Transparent glass ceramics are composite materials in which nanocrystals are distributed in an amorphous glass phase. Since transparent glass ceramics have several potential applications in photonics, it is important to evaluate the incorporation of the activator ions in the crystalline phase and to quantify its optical properties. Glass ceramics containing CaF2 crystalline phase with Eu3+ concentration 0.5, 1, 1.5, 2, 5 and 10 mol% were synthesised. X-ray diffraction measurements were performed on the samples, which allowed to evaluate the efficiency of incorporation of activator ions using the change of the lattice constant as a function of Eu3+ concentration. Luminescence excitation spectra in the spectral region from 420 nm to 530 nm were measured and the characteristic luminescence bands of Eu3+ were observed. The intensity of luminescence increases with the increase of trivalent europium ion concentration. Site selective spectroscopy was used to determine the number of nonequivalent crystallographic positions of europium ions in glass ceramics. Luminescence quantum yield of the samples and its dependence on the annealing temperature of glass ceramics, as well as the Eu3+ concentration was determined.

Bakalaura darba ietvaros ar ierosmes, luminiscences un tās kinētikas spektru palīdzību tika pētīti jauni, ar sarkanu gaismu luminiscējoši, aktivēti platzonu materiāli uz AlN bāzes. Darba ietvaros tika aplūkoti AlN makro- un nanopulveri, ar mangānu aktivēti AlN makro- un nanomateriāli, kā arī ar eiropiju aktivētas keramikas. Apskatītajiem materiāliem tika noteiktas to spektrālās īpašības., New, red-light luminescent, activated wide band-gap materials, based on AlN, were studied using excitation, luminescence and its kinetic spectra. Within the bachelor's thesis, AlN macro- and nanopowders, manganese-activated AlN macro- and nanomaterials, as well as europium-activated ceramics were investigated. The spectral properties of the considered materials were determined.

Literatūras apskatā aplūkota luminiscence, enerģijas pārnese, agregācijas izraisītās dzēšanas (ACQ) un agregācijas inducētās emisijas (AIE) luminiscenci ietekmējošie efekti. Iekļauti ACQ un AIE luminoforu piemēri un emisijas mehānismi. Rezultātu izvērtējumā aplūkotas veiktās sintēzes, analizētas iegūto savienojumu optiskās īpašības, iegūtās rentgenstruktūras un savienojumu optimizēto ģeometriju rezultāti. Darba eksperimentālajā daļā sintezēti 28 savienojumi. 3 no tiem ir benziltipa katjonās daļas saturoši savienojumi, 6 – piridīna atvasinājumi un 17 – piridīnija atvasinājumi, bet 2 ir starpprodukti. Aprakstītas sintēžu metodes, iekļauti vielu raksturojumi, izmantojot 1H–KMR, 13C–KMR, IS un AIMS analīzes metodes., Luminescence, energy transfer, aggregation caused quenching (ACQ) and aggregation induced emission (AIE) effects on luminescence have been discussed in a literature review. ACQ and AIE examples and emission mechanisms are included. Discussion includes an overview of synthesis, analysis of photophysical properties, acquired X–rays and results of optimized geometries of synthesized compounds. The experimental part includes synthesis of 28 compounds. 3 of them are cationic moiety containing benzyl type desired luminophores, 6 – pyridine moiety containing luminophores, 17 – pyridinium moiety containing desired luminophores, and 2 are intermediates. Synthetic procedures and the characterization of obtained compounds using 1H–NMR, 13C–NMR, IR and HRMS methods are included.