Neste trabalho demonstramos a preparação de fluorenos e benzo[b]fluorenos por uma nova rota sintética, baseada na reação de Diels-Alder de derivados benzo[5]radialênicos. Para a preparação destes últimos investigamos diversas estratégias, partindo de p-benzoquinona e três dienos: 1,1-dimetoxiciclopentadieno, 6,6-dimetilfulveno e 6-acetoxifulveno. A partir de cada fulveno obtivemos um benzo[5]radialeno diferente, sendo que o derivado dimetilado se mostrou inerte como dieno em cicloadições. O benzo[5]radialeno derivado do 6-acetoxifulveno, reagiu com diversos dienófilos tais como p-benzoquinona, 2,3-dicloro-p-benzoquinona, 1,4-naftoquinona, N-metilmaleimida, acetilenodicarboxilato de dimetila, acrilato de metila, etc. Notamos uma alta quimiosseletividade entre os sistemas diênicos, pois obtivemos apenas adutos trans. Com alguns dienófilos observamos a formação de compostos aromatizados (formados pela eliminação de ácido acético que, para os casos pertinentes, foi regiosseletiva). Com dienófilos como acrilato de metila ou sulfinil-naftoquinonas, alta regiosseletividade foi observada. Tentamos explorar tais seletividades para a preparação de análogos da eucapsitriona. Os adutos de Diels-Alder obtidos constituem exemplos de derivados fluorênicos e benzo[b]fluorênicos que, ultimamente, têm recebido grande atenção tanto por aspectos estruturais como por apresentarem propriedades biológicas importantes / In this work we demonstrated the preparation of fluorenes and benzo[b]fluorenes by a new synthetic route, based on the Diels-Alder reaction of benzo[5]radialenes derivatives. For the preparation of the last we investigated several strategies starting from p-benzoquinone and three dienes: 1,1-dimethoxycyclopentadiene, 6,6-dimethylfulvene and 6-acetoxyfulvene. From each fulvene we obtained a different benzo[5]radialene, but the dimethylated one showed no reactivity in cycloadditions. The benzo[5]radialene prepared from 6-acetoxyfulvene reacted with several dienophiles such as p-benzoquinone, 2,3-dichloro-p-benzoquinone, 1,4-naphtoquinone, N-methylmaleimide, dimethyl acetylenedicarboxylate, methyl acrylate, etc. We noted a high quimiosselectivity between the dienic sub units since only trans adducts were obtained. With some dienophiles we observed the formation of aromatized compounds (formed by acetic acid elimination which, for suitable cases, was regiosselective). With dienophiles such as methyl acrylate or sulfinyl-naphtoquinones high regiosselectivity was observed. We tried to explore such selectivities to prepare eucapsitrione analogues. These Diels-Alder adducts are examples of fluorenic and benzo[b]fluorenic derivatives, compounds that have gained considerable attention due to structural and biological aspects.

Neste trabalho demonstramos a preparação de fluorenos e benzo[b]fluorenos por uma nova rota sintética, baseada na reação de Diels-Alder de derivados benzo[5]radialênicos. Para a preparação destes últimos investigamos diversas estratégias, partindo de p-benzoquinona e três dienos: 1,1-dimetoxiciclopentadieno, 6,6-dimetilfulveno e 6-acetoxifulveno. A partir de cada fulveno obtivemos um benzo[5]radialeno diferente, sendo que o derivado dimetilado se mostrou inerte como dieno em cicloadições. O benzo[5]radialeno derivado do 6-acetoxifulveno, reagiu com diversos dienófilos tais como p-benzoquinona, 2,3-dicloro-p-benzoquinona, 1,4-naftoquinona, N-metilmaleimida, acetilenodicarboxilato de dimetila, acrilato de metila, etc. Notamos uma alta quimiosseletividade entre os sistemas diênicos, pois obtivemos apenas adutos trans. Com alguns dienófilos observamos a formação de compostos aromatizados (formados pela eliminação de ácido acético que, para os casos pertinentes, foi regiosseletiva). Com dienófilos como acrilato de metila ou sulfinil-naftoquinonas, alta regiosseletividade foi observada. Tentamos explorar tais seletividades para a preparação de análogos da eucapsitriona. Os adutos de Diels-Alder obtidos constituem exemplos de derivados fluorênicos e benzo[b]fluorênicos que, ultimamente, têm recebido grande atenção tanto por aspectos estruturais como por apresentarem propriedades biológicas importantes / In this work we demonstrated the preparation of fluorenes and benzo[b]fluorenes by a new synthetic route, based on the Diels-Alder reaction of benzo[5]radialenes derivatives. For the preparation of the last we investigated several strategies starting from p-benzoquinone and three dienes: 1,1-dimethoxycyclopentadiene, 6,6-dimethylfulvene and 6-acetoxyfulvene. From each fulvene we obtained a different benzo[5]radialene, but the dimethylated one showed no reactivity in cycloadditions. The benzo[5]radialene prepared from 6-acetoxyfulvene reacted with several dienophiles such as p-benzoquinone, 2,3-dichloro-p-benzoquinone, 1,4-naphtoquinone, N-methylmaleimide, dimethyl acetylenedicarboxylate, methyl acrylate, etc. We noted a high quimiosselectivity between the dienic sub units since only trans adducts were obtained. With some dienophiles we observed the formation of aromatized compounds (formed by acetic acid elimination which, for suitable cases, was regiosselective). With dienophiles such as methyl acrylate or sulfinyl-naphtoquinones high regiosselectivity was observed. We tried to explore such selectivities to prepare eucapsitrione analogues. These Diels-Alder adducts are examples of fluorenic and benzo[b]fluorenic derivatives, compounds that have gained considerable attention due to structural and biological aspects.

Le monoxyde d'azote (NO•) est connu pour son rôle dans de nombreux processus biologiques et physiologiques. Il peut cependant avoir des effets antagonistes selon sa concentration dans le milieu. Le développement de sources exogènes capables de relarguer localement et quantitativement NO• est donc nécessaire pour profiter pleinement de son potentiel thérapeutique. La chimiothérapie photoactivée offre une approche intéressante qui consiste en l'irradiation de systèmes photosensibles non toxiques dans l'obscurité, mais capables de déclencher la mort cellulaire sous activation à la lumière. Cette thèse s'articule autour de trois complexes de ruthénium nitrosyle (RuNO) à ligands polypyridines, développés dans la perspective d'étudier leur comportement par excitation mono- et biphotonique. La fonctionnalisation des ligands polypyridines par des groupements riches en électrons permet d'envisager une excitation à 2 photons dans la fenêtre thérapeutique afin de traiter de manière locale des tumeurs plus profondes. Un état de l'art sur ces enjeux et cette thématique est dressé dans le premier chapitre. Dans le deuxième chapitre, une étude théorique comparative de plusieurs complexes RuNO à ligand bipyridine fonctionnalisée par des fluorènes permet de sélectionner le meilleur candidat pour la photolibération de NO•. Dans le troisième chapitre, la synthèse et la caractérisation de [Ru(terpy)(F2bpy)(NO)](PF6)3 (terpy = 2,2':6',2''-terpyridine; F2bpy = 4,4'-bis(9,9'-dibutyl-9H-fluoren-2-yl)-2,2'-bipyridine) sont décrites. Sont ensuite présentées dans le quatrième chapitre la synthèse et la caractérisation de [Ru(terpy)(MP2bpy)(NO)](PF6)3 (T0B2) et [Ru(MPterpy)(MP2bpy)(NO)](PF6)3 (T1B2), avec MP2bpy = 4,4'-bis(4-méthoxyphényl)-2,2'-bipyridine et MPterpy = 4'-(4-méthoxyphényl)-2,2':6',2''-terpyridine. Dans le cinquième chapitre, les propriétés photophysiques de [Ru(terpy)(F2bpy)(NO)](PF6)3 sous excitation à un photon et à deux photons sont étudiées, la libération de NO• est mise en évidence (détermination du rendement quantique фNO et de la section efficace σ) et le photoproduit est caractérisé. Le comportement des complexes T0B2 et T1B2 sous irradiation monophotonique est étudié dans le sixième chapitre, à travers la photolibération de NO•, la caractérisation de leur photoproduit et la détermination de фNO. / Nitric oxide (NO•) is known for its role in many biological and physiological processes. Nonetheless its effects are opposite according to the concentration in the media. The development of exogeneous sources able to release locally and quantitatively NO• is therefore necessary to fully benefit from its therapeutic potential. Photoactivated chemotherapy offers an interesting approach consisting in the irradiation of non toxic photoreactive systems in the dark, but able to trigger cell death when irradiated with light. This thesis is based on three ruthenium nitrosyl complexes (RuNO) with polypyridyl ligands, developed in view of studying their behavior under mono- and biphotonic excitation. The functionalization of polypyridyl ligands by electron-rich groups enables to consider a two-photon excitation in the therapeutic window in order to access deeper tumors locally. A state of art on those stakes and on this theme is addressed in the first chapter. In the second chapter, a comparative theoretical study of several RuNO complexes with a bipyridine ligand functionalized with fluorene enables to select the best candidate for NO• photorelease. In the third chapter, the synthesis and the characterization of [Ru(terpy)(F2bpy)(NO)](PF6)3 (terpy = 2,2':6',2''-terpyridine; F2bpy = 4,4'-bis(9,9'-dibutyl-9H-fluoren-2-yl)-2,2'-bipyridine) are detailed. In the fourth chapter are presented the synthesis and characterization of [Ru(terpy)(MP2bpy)(NO)](PF6)3 (T0B2) and [Ru(MPterpy)(MP2bpy)(NO)](PF6)3 (T1B2), with MP2bpy = 4,4'-bis(4-methoxyphenyl)-2,2'-bipyridine et MPterpy = 4'-(4-methoxyphenyl)-2,2':6',2''-terpyridine. In the fifth chapter, the photophysical properties of [Ru(terpy)(F2bpy)(NO)](PF6)3 under one-photon and two-photon excitation are studied, NO• release is demonstrated (determination of the quantum yield фNO and the cross section σ) and the photoproduct is characterized. The behavior of T0B2 and T1B2 under monophotonic irradiation is described in the sixth chapter, through the photorelease of NO•, the characterization of their photoproduct, and the determination of фNO.

The synthesis and characterization of two donor acceptor type conjugated polymers were investigated. The electrochemical properties were examined using cyclic voltammetry, spectroelectrochemistry and kinetic studies. The increase in the alkyl chain length attached to the fluorene unit was investigated by the corresponding electrochemical characteristics. The synthesis was carried out via Stille coupling of 4,7- dibromo-4&#039 / -(tert-butyl)spiro[benzo[d]imidazole-2,1&#039 / cyclohexane] and 2,5- bis(tributylstannyl)thiophene with 9,9-dihexyl-9H fluorene and 9,9-didodecyl-9H fluorene respectively. Both of the polymers were neutral state green polymers. They had optical band gaps of 2.46 and 2.54 eV respectively. Increasing the chain length resulted in an increase in solubility and processibility of the polymer but also an increase in the band gap. This was due to the increased bulkyness of the alkyl group, leading to a decrease in the effective conjugation and planarity. They both had distinctive &pi / -&pi / * transitions, band structure and backbone that provides oxidative doping. P1, with the shorter alkyl chain had a lower oxidation potential than P2. Neither of the polymers was capable of being n-doped. They were both multichromic, revealing colors from neutral state green to doped state blue.

Depuis deux décennies, la modernisation des techniques d’imagerie de fluorescence a permis decomprendre et d’étudier de nombreux processus biologiques. Ce formidable essor a néanmoins étéralenti par les faibles performances des sondes fluorescentes disponibles pour ce type d’imagerie. Cemanque d’objets luminescents a motivé des recherches intenses dans le but d’optimiser les sondesmoléculaires fluorescentes déjà existantes afin de leur permettre d’être plus fluorescentes, mais aussiplus stables. En parallèle à ces optimisations, l’avancée des nanotechnologies à permis de développerde nouveaux outils pour l’imagerie biologique. Du fait de leurs propriétés optiques, de leur excellentephotostabilité, ainsi que la possibilité de fonctionnaliser leur surface, les nanoparticules semiconductrices(QDs) ont connu un succès phénoménal dans les domaines de l’imagerie. Au fur et àmesure de leur utilisation, de nombreuses questions partiellement élucidées sur la toxicité des QDs ontémergé. Dans le but de proposer une alternative aux QDs, de nombreux groupes de recherche onttravaillé sur la préparation de nanoparticules (ONPs) à base de molécules organiques, ce qui a mis finà l’hégémonie des QDs en imagerie biologique. Parmi ces ONPs, les nanoparticules fluorescentes àbase de molécules organiques (FONs) se sont imposées comme des candidats sérieux pour sonder levivant. Dans cette optique, nous développons de nouveaux chromophores qui, par un designmoléculaire adapté, peuvent former des FONs avec des brillances à un et deux photons comparables àcelle des QDs tout en étant biocompatibles. / Since decades, bioimaging technics increased a lot, thus leading to a better understanding of biologicalprocesses. However, the fluorescence imaging was limited due to the low photostability and brightnessof available organic dyes. In order to improve the lack of photostability and brightness of thecommercially available dyes, lots of effort was done by organic chemists. In the mean time with theincoming of nanotechnologies, new tools such as the semi-conductors QDs raised as promisingluminescent probes for bioimaging. Due to their intrinsic properties, QDs are bright and photostablenano-objects, furthermore, the labeling of the surface of the QDs is of interest for targeting (such asthe detection of cancer cells). Despite their popularity, with time, issues about the clearance and thetoxicity of the QDs have been adressed and are still not fully solved. So the development of safer andbiocompatible tools for bioimaging emerged as evidence for scientists. In that context, the use ofnanoparticles made of organic materials gain in interest and particularly the fluorescent organicnanoparticles (FONs). We aimed to propose biocompatible and safer alternative to QDs, so wedeveloped new nanotools, based on the self aggregation of propeller-shaped fluorophores as FONs.Because of the specific design of the chromophores, these FONs have large one and two-photonbrightness combine with good photostability. These features made these FONs promising tools foreither one-photon and two-photon fluorescence imaging in cells and in vivo.

The literature surrounding organic small-molecule donor-acceptor systems is summarised for a range of optoelectronic applications (OLEDs, OPVs, OFETs etc.). There is a focus on the key building blocks: 1,3,4-oxadiazole (OXD), diphenylamine (DPA), carbazole (Cbz) and fluorene (F). The incorporation of such moieties into various donor-acceptor systems is discussed with further reference to selected alternative organic donor and acceptor systems. The syntheses of novel bipolar molecules based on a donor-spacer-acceptor (DPA/Cbz-F-OXD) structure and the incorporation of these molecules into single-layer OLEDs is presented. It is demonstrated how the emission colour can be tuned from green to deep blue by systematic manipulation of the structure. A significant result is that high efficiency accompanied with pure, deep blue emission in single-layer OLEDs can be achieved with this structural motif. The incorporation of these materials as part of a simple two-component blend to produce white OLEDs is presented and the modification of the materials to improve electron-transport properties is discussed. The synthesis of DPA-bridge-OXD wire systems is presented with the use of oligo-p-phenyleneethynylene units as a bridge of varying length to investigate the effect on charge transfer between the donor and acceptor. Photophysical studies demonstrate the change in absorption, emission and fluorescence lifetimes as the length scale of the molecules is altered. The synthesis of a series of planarised and twisted DPA-bridge-OXD systems based upon phenylene linkers is discussed. Finally, a series of DPA-F-OXD-anchor molecules is presented for incorporation into DSSC devices. The synthesis of these materials is described and the suitability of various anchoring groups for DSSCs is analysed through photophysical and device studies.

No description available.

Neste trabalho estudamos a dinâmica molecular e o empacotamento em semicondutores orgânicos com diferentes tamanhos de cadeias conjugada usando uma estratégia de multi-técnicas, em particular Ressonância Magnética Nuclear (RMN), espalhamento de Raios-X de alto ângulo (WAXS), Calorimetria Exploratória Diferencial (DSC), espectroscopia Raman e espectroscopias Ópticas de absorção UV-Vis e fluorescência. Nestes estudos utilizamos oligômeros de fluorenos, com 3, 5 e 7 unidades repetitivas e copolímeros multibloco conjugados/não-conjugados com as unidades conjugadas constituídas por unidades de fenileno de vinileno (PV) e as não-conjugadas formadas por unidades metilênicas. No estudo com oligômeros, foi mostrado que a capacidade e a forma de ordenamento das cadeias dependem do número de unidades repetitivas, com o Pentâmero possuindo uma tendência muito maior de cristalização. Essa conclusão foi suportada por cálculos teóricos ab-initio, que mostraram que a conformação de menor energia do pentâmero favorece as interações intercadeias e, portanto, o ordenamento de longo alcance. Os resultados referentes aos estudos de dinâmica molecular corroboraram essas características e mostraram que a ativação dos movimentos moleculares nas fases amorfas dos oligômeros são predominantemente dependentes dos comprimentos das cadeias oligoméricas, em concordância com o comportamento encontrado para as suas Tg´s. No estudo referente aos copolímeros multiblocos, foi encontrado que a presença dos grupos espaçadores alifáticos inibem a forte tendência de cristalização das unidades de PV, porém não impedem a agregação dessas unidades. Foi verificado que, a dispersão de tamanhos das unidades agregadas afeta fortemente as características de emissão dos copolímeros, onde a emissão nas cadeias maiores é privilegiada. No que diz respeito a dinâmica molecular, foi observado que a presença de movimentos na região alifática contribui para o aparecimento de processos de relaxação não radiativos o qual inibem a emissão dos copolímeros e provocam alargamento das bandas vibrônicas. Por fim, foi observado que movimentos isotrópicos das cadeias de PV são responsáveis pela transição vítrea dos copolímeros, sendo que as energias necessárias para ativar esses movimentos aumentam com o tamanho da cadeia. Portanto, de forma geral, nossos resultados indicam que mesmo em sistemas com comprimento de cadeias muito bem controlados, as fortes interações intermoleculares presentes em polímeros conjugados, podem tornar a morfologia em estado sólido desses sistemas bastante complexa, sendo que muitas das propriedades ópticas (e provavelmente também elétricas) são afetadas pela forma de empacotamento, desordem conformacional e térmica, além da própria constituição das cadeias. / In this dissertation we present a study of the molecular dynamics and packing in organics semiconductor with different conjugated chains lengths using a of multi-techniques approach, in particular, Nuclear Magnetic Resonance (NMR), Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC), Raman spectroscopy, UV-Vis absorption and fluorescence spectroscopy. The studies were carried-in fluorene oligomers with 3, 5 and 7 repeat units and multi-block conjugated/non-conjugated copolymers with the conjugated part formed by phenylene-vinylene units (PV) and the non-conjugated block formed by methylene units. Concerning the oligomers studies, it was shown that the ability of the chain to form ordered domains as well as the domain structure depend on the number of repeat units, with the pentamer having a higher tendency to crystallization. This conclusion was supported by theoretical ab-initio calculations, which showed that the pentamer conformation favors inter-chain interactions and therefore long-range ordering. The molecular dynamics studies support these characteristics and showed that the activation of molecular motions in oligomers amorphous phase are predominantly dependent on the oligomeric chain lengths, in agreement with the behavior observed for their glass transitions (Tg´s). In the study concerning the multi-block copolymers, it was found that presence of the aliphatic chains inhibit the strong tendency to crystallization of the PV units, but do not prevent their aggregation. It was found that the dispersion in aggregated units sizes strongly affects the copolymers emission, with the emission of larger chains being privileged. Regarding the molecular dynamics, we observed that the presence of motion on aliphatic region contributes to the appearance of non-radiative relaxation processes that inhibit the emission of the copolymers and produce broadening of the vibronic bands. Finally, we observed that isotropic motions of the PV chains are responsible for the copolymers glass transition and the energy required to activate these movements increase with length of the chain. In summary, our results indicate that even in systems with well controlled chains length, the strong intermolecular interactions present in conjugated polymers, can make the solid state morphology of these systems quite complex, which may affect many optical (and probably electric) properties are affected by the packaging structure, thermal and conformational disorder, in addition to the constitution of the chains composition.

Η διφωτονική απορρόφηση (ΔΦΑ) είναι το μη γραμμικό-φαινόμενο κατά το οποίο δύο φωτόνια απορροφούνται ταυτόχρονα σε ένα υλικό μέσο. Τα τελευταία 20 χρόνια το φαινόμενο αυτό έχει προσελκύσει ιδιαίτερα το ενδιαφέρον της επιστημονικής κοινότητας για την ανακάλυψη νέων αποδοτικών ενώσεων λόγω και των εφαρμογών που έχει βρεθεί ότι μπορεί να προσφέρει. Η διφωτονική μικροσκοπία, ο διφωτονικός πολυμερισμός, η τρισδιάστατη αποθήκευση δεδομένων είναι μερικές από τις σημαντικές εφαρμογές που εκμεταλλεύονται τα πλεονεκτήματα της ΔΦΑ. Τη τελευταία δεκαετία η έρευνα επικεντρώνεται στη θεωρητική και πειραματική μελέτη της ΔΦΑ οργανικών ενώσεων με σκοπό την διασύνδεσης των χαρακτηριστικών της δομής των μορίων με την ΔΦΑ που παρέχουν και την εύρεση στρατηγικών σύνθεσης οργανικών ενώσεων υψηλής ΔΦΑ. Επίσης πολλές είναι οι επιστημονικές εργασίες που χρησιμοποιούν τις ενώσεις αυτές στην έρευνα για την ανάπτυξη και βελτίωση των διφωτονικών εφαρμογών. Στη διατριβή αυτή γίνεται μελέτη της ΔΦΑ συζυγιακών οργανικών ενώσεων αποτελούμενες από ένα κεντρικό τμήμα συνδεδεμένο αντιδιαμετρικά με δυο ίδιους υποκαταστάτες. Τα συμμετρικά αυτά μόρια έχουν ως κεντρικό τμήμα φλουορένιο ή αλκόξυ-φαινυλένιο ή καρβοξύλιο και διάφορους υποκαταστάτες στα άκρα. Η τεχνική μέτρησης διφωτονικά διεγερμένου φθορισμού με laser femtosecond χρησιμοποιήθηκε για τον υπολογισμό των τιμών της ενεργούς διατομής ΔΦΑ των μορίων στη φασματική περιοχή 750-840nm. Από τη συγκριτική μελέτη των ενώσεων προκύπτει ότι ο υποκαταστάτης φθαλιμίδιο προσφέρει την μεγαλύτερη ΔΦΑ και για τα τρία διαφορετικά κεντρικά τμήματα, ενώ όταν συνδέεται με το φλουορένιο έχει την υψηλότερη ενεργό διατομή ΔΦΑ φθάνοντας την τιμή των 1650GM στη φασματική περιοχή που μελετήθηκε. Επίσης παρατηρήθηκε ότι ο υποκαταστάτης ναφθαλιμίδιο προκαλεί μετατόπιση του μεγίστου ΔΦΑ σε αρκετά μεγαλύτερα μήκη κύματος. Παρόμοια μετατόπιση παρατηρείται και για τα μόρια με κεντρικό τμήμα το καρβαζόλιο. Η μετατόπιση αυτή του φάσματος ΔΦΑ δεν αντιστοιχεί σε μετατόπιση του φάσματος μονοφωτονικής απορρόφησης. Οφείλεται στην άρση της κεντροσυμμετρίας του μορίου, λόγω της διαμόρφωσης της δομής του, η οποία κάνει επιτρεπτή τη διφωτονική μετάβαση στην πρώτη μονοφωτονικά επιτρεπτή ενεργειακή κατάσταση που ειδάλλως είναι απαγορευμένη. Η επίδραση του διαλύτη στις διφωτονικές ιδιότητες των μορίων μελετάται επίσης στη διατριβή αυτή. Για τις τέσσερις πιο αποδοτικές ενώσεις, ως προς το διφωτονικά διεγερμένο φθορισμό, έγιναν μετρήσεις για τον υπολογισμό των φασμάτων ΔΦΑ τους σε πέντε διαλύτες διαφορετικής πολικότητας (διηλεκτρικής σταθεράς). Από τις μετρήσεις φάνηκε η σημαντική επίδραση του διαλύτη στη ΔΦΑ των τεσσάρων χρωστικών η οποία μεγιστοποιείται σε διαλύτη μεσαίας πολικότητας, ο τρεις στην ακετοφαινόνη και μια στο THF. Η χαμηλή κβαντική απόδοση φθορισμού που παρατηρείται στα διαλύματα με ακετοφαινόνης μειώνει αρκετά το διφωτονικά προκαλούμενο φθορισμό και κατατάσσει τo THF ως τον αποδοτικότερο διαλύτη για διφωτονικές εφαρμογές που εκμεταλλεύονται το φθορισμό. Επίσης και ο μη πολικός διαλύτης τολουόλιο προκαλεί έντονο φθορισμό λόγω της υψηλής κβαντικής απόδοσης παρόλο που επιφέρει δραστική μείωση της ΔΦΑ σε σύγκριση με τους άλλους διαλύτες που μελετήθηκαν. Δύο από τις χρωστικές που μελετήθηκαν ως προς τη ΔΦΑ τους χρησιμοποιήθηκαν ως φωτοεκκινητής πολυμερισμού ενός ακρυλικού μονομερούς και την μελέτη του πολυμερισμού συναρτήσει διαφόρων παραμέτρων ακτινοβόλησης της ρητίνης. Οι χρωστικές αυτές έχουν φλουορένιο ως κεντρικό τμήμα και υποκαταστάτες στα άκρα φθαλιμίδιο ή τριφαινυλαμίνη. Και οι δύο χρωστικές δύναται να προκαλέσουν τον πολυμερισμό του μονομερούς με ακτινοβόληση υπερβραχέων παλμών στα 800nm, αλλά η προσθήκη αμίνης ως συνεκκινητή μειώνει το κατώφλι ισχύος εκκίνησης του. Επίσης, σε υψηλές τιμές ισχύος ακτινοβόλησης στο ίδιο μήκος κύματος παρατηρήθηκε αυτο-πολυμερισμός του μονομερούς γεγονός το οποίο έχει επισημανθεί μία μόνο ακόμη φορά σε μια εργασία με ρητίνη μίξης τριών ακρυλικών μονομερών. Δύο ρητίνες που παρασκευάστηκαν στην παρούσα διατριβή αναμιγνύοντας το μονομερές με τη κάθε χρωστική και με προσθήκη του συνεκκινητή μελετήθηκαν για την εξάρτηση του πολυμερισμού από τον φακό εστίασης και από την ισχύ, την ταχύτητα σάρωσης και τη διάμετρο της δέσμης. Για το σκοπό αυτό κατασκευάστηκαν δοκίμια στα οποία εγγράφονταν πολυμερισμένες γραμμές μεταβάλλοντας κάποια από τις παραπάνω παραμέτρους και μετρώντας το πάχος και το ύψος των γραμμών αυτών από τις εικόνες μικροσκοπίου σάρωσης ηλεκτρονίων. Το γεγονός ότι ο μικρότερης ισχύος φακός παρατηρηθηκε ότι προκαλεί λεπτότερη γραμμή εξηγείται από το φαινόμενο κατωφλίου του πολυμερισμού. Ωστόσο η λεπτότερη γραμμή επιτυγχάνεται με τον ισχυρότερο φακό καθώς μπορεί να μειωθεί περισσότερο η ισχύς της δέσμης λόγω του χαμηλότερου κατωφλίου εκκίνησης του πολυμερισμού για το φακό αυτό. Η αύξηση της ταχύτητας σάρωσης ή η μείωση της ισχύος της δέσμης επιφέρουν μικρότερες διαστάσεις πάχους και ύψους της γραμμής που πολυμερίζεται. Επίσης η κατανομή της ισχύος ακτινοβόλησης σε ολόκληρο το πίσω άνοιγμα του φακού επιφέρει καλύτερη εστίαση και λεπτότερη πολυμερισμένη γραμμή. Ωστόσο η κατάλληλη χωρική διαμόρφωση της δέσμης μπορεί να μειώσει τις διαστάσεις των πολυμερισμένων δομών. / -

Neste trabalho estudamos a dinâmica molecular e o empacotamento em semicondutores orgânicos com diferentes tamanhos de cadeias conjugada usando uma estratégia de multi-técnicas, em particular Ressonância Magnética Nuclear (RMN), espalhamento de Raios-X de alto ângulo (WAXS), Calorimetria Exploratória Diferencial (DSC), espectroscopia Raman e espectroscopias Ópticas de absorção UV-Vis e fluorescência. Nestes estudos utilizamos oligômeros de fluorenos, com 3, 5 e 7 unidades repetitivas e copolímeros multibloco conjugados/não-conjugados com as unidades conjugadas constituídas por unidades de fenileno de vinileno (PV) e as não-conjugadas formadas por unidades metilênicas. No estudo com oligômeros, foi mostrado que a capacidade e a forma de ordenamento das cadeias dependem do número de unidades repetitivas, com o Pentâmero possuindo uma tendência muito maior de cristalização. Essa conclusão foi suportada por cálculos teóricos ab-initio, que mostraram que a conformação de menor energia do pentâmero favorece as interações intercadeias e, portanto, o ordenamento de longo alcance. Os resultados referentes aos estudos de dinâmica molecular corroboraram essas características e mostraram que a ativação dos movimentos moleculares nas fases amorfas dos oligômeros são predominantemente dependentes dos comprimentos das cadeias oligoméricas, em concordância com o comportamento encontrado para as suas Tg´s. No estudo referente aos copolímeros multiblocos, foi encontrado que a presença dos grupos espaçadores alifáticos inibem a forte tendência de cristalização das unidades de PV, porém não impedem a agregação dessas unidades. Foi verificado que, a dispersão de tamanhos das unidades agregadas afeta fortemente as características de emissão dos copolímeros, onde a emissão nas cadeias maiores é privilegiada. No que diz respeito a dinâmica molecular, foi observado que a presença de movimentos na região alifática contribui para o aparecimento de processos de relaxação não radiativos o qual inibem a emissão dos copolímeros e provocam alargamento das bandas vibrônicas. Por fim, foi observado que movimentos isotrópicos das cadeias de PV são responsáveis pela transição vítrea dos copolímeros, sendo que as energias necessárias para ativar esses movimentos aumentam com o tamanho da cadeia. Portanto, de forma geral, nossos resultados indicam que mesmo em sistemas com comprimento de cadeias muito bem controlados, as fortes interações intermoleculares presentes em polímeros conjugados, podem tornar a morfologia em estado sólido desses sistemas bastante complexa, sendo que muitas das propriedades ópticas (e provavelmente também elétricas) são afetadas pela forma de empacotamento, desordem conformacional e térmica, além da própria constituição das cadeias. / In this dissertation we present a study of the molecular dynamics and packing in organics semiconductor with different conjugated chains lengths using a of multi-techniques approach, in particular, Nuclear Magnetic Resonance (NMR), Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC), Raman spectroscopy, UV-Vis absorption and fluorescence spectroscopy. The studies were carried-in fluorene oligomers with 3, 5 and 7 repeat units and multi-block conjugated/non-conjugated copolymers with the conjugated part formed by phenylene-vinylene units (PV) and the non-conjugated block formed by methylene units. Concerning the oligomers studies, it was shown that the ability of the chain to form ordered domains as well as the domain structure depend on the number of repeat units, with the pentamer having a higher tendency to crystallization. This conclusion was supported by theoretical ab-initio calculations, which showed that the pentamer conformation favors inter-chain interactions and therefore long-range ordering. The molecular dynamics studies support these characteristics and showed that the activation of molecular motions in oligomers amorphous phase are predominantly dependent on the oligomeric chain lengths, in agreement with the behavior observed for their glass transitions (Tg´s). In the study concerning the multi-block copolymers, it was found that presence of the aliphatic chains inhibit the strong tendency to crystallization of the PV units, but do not prevent their aggregation. It was found that the dispersion in aggregated units sizes strongly affects the copolymers emission, with the emission of larger chains being privileged. Regarding the molecular dynamics, we observed that the presence of motion on aliphatic region contributes to the appearance of non-radiative relaxation processes that inhibit the emission of the copolymers and produce broadening of the vibronic bands. Finally, we observed that isotropic motions of the PV chains are responsible for the copolymers glass transition and the energy required to activate these movements increase with length of the chain. In summary, our results indicate that even in systems with well controlled chains length, the strong intermolecular interactions present in conjugated polymers, can make the solid state morphology of these systems quite complex, which may affect many optical (and probably electric) properties are affected by the packaging structure, thermal and conformational disorder, in addition to the constitution of the chains composition.