Made available in DSpace on 2014-12-17T15:41:55Z (GMT). No. of bitstreams: 1 DanielleOM_DISSERT.pdf: 1963445 bytes, checksum: 143b241474d5026def897c0c4c0d797f (MD5) Previous issue date: 2011-07-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work were synthesized and studied the spectroscopic and electrochemical characteristics of the coordination compounds trans-[Co (cyclam)Cl2]Cl, trans- Na[Co(cyclam)(tios)2], trans-[Co(en)2Cl2]Cl and trans-Na[Co(en)2(tios)2], where tios = thiosulfate and en = ethylenediamine. The compounds were characterized by: Elemental Analysis (CHN), Absorption Spectroscopy in the Infrared (IR), Uv-Visible Absorption Spectroscopy, Luminescence Spectroscopy and Electrochemistry (cyclic voltammetry). Elemental Analysis (CHN) suggests the following structures for the complex: trans- [Co(cyclam)Cl2]Cl.6H2O and trans-Na[Co(cyclam)(tios)2].7H2O. The electrochemical analysis, when compared the cathodic potential (Ec) processes of the complexes trans- [Co(cyclam)Cl2]Cl and trans-[Co(en)2Cl2]Cl, indicated a more negative value (-655 mV) for the second complex, suggesting a greater electron donation to the metal center in this complex which can be attributed to a greater proximity of the nitrogen atoms of ethylenediamine in relation to metal-nitrogen cyclam. Due to the effect of setting macrocyclic ring to the metal center, the metal-nitrogen bound in the cyclam are not as close as the ethylenediamine, this fact became these two ligands different. Similar behavior is also observed for complexes in which the chlorides are replaced by thiosulfate ligand, trans-Na[Co(en)2(tios)2] (-640 mV) and trans-Na[Co(cyclam)(tios)2] (-376 mV). In absorption spectroscopy in the UV-visible, there is the band of charge transfer LMCT (ligand p d* the metal) in the trans-Na[Co(cyclam)(tios)2] (350 nm, p tios  d* Co3+) and in the trans-Na[Co(en)2(tios)2] (333 nm, p tios d* Co3+), that present higher wavelength compared to complex precursor trans- [Co(cyclam)Cl2]Cl (318 nm, pCl  d* Co3+), indicating a facility of electron density transfer for the metal in the complex with the thiosulfate ligand. The infrared analysis showed the coordination of the thiosulfate ligand to the metal by bands in the region (620-635 cm-1), features that prove the monodentate coordination via the sulfur atom. The νN-H bands of the complexes with ethylenediamine are (3283 and 3267 cm-1) and the complex with cyclam bands are (3213 and 3133 cm-1). The luminescence spectrum of the trans-Na[Co(cyclam)(tios)2] present charge transfer band at 397 nm and bands dd at 438, 450, 467, 481 and 492 nm. / Este trabalho teve por objetivo sintetizar e estudar as caracter?sticas espectrosc?picas e eletroqu?micas dos compostos de coordena??o trans- Na[Co(cyclam)(tios)2], trans-[Co(cyclam)Cl2]Cl, trans-[Co(en)2Cl2]Cl e trans- Na[Co(en)2(tios)2], em que tios = tiossulfato e en = etilenodiamina. Os compostos obtidos foram caracterizados por: An?lise elementar (CHN), Espectroscopia de Absor??o na Regi?o do Infravermelho (IV), Espectroscopia de Absor??o na Regi?o do UV-Vis?vel, Espectroscopia de Luminesc?ncia e Eletroqu?mica (voltametria c?clica). A an?lise elementar (CHN) sugere as seguintes estruturas para os complexos: trans- [Co(cyclam)Cl2]Cl.6H2O e trans-Na[Co(cyclam)(tios)2].7H2O. Na an?lise eletroqu?mica, ao se fazer uma compara??o dos potenciais cat?dicos (Ec) referentes aos processos de redu??o dos complexos trans-[Co(cyclam)Cl2]Cl e trans-[Co(en)2Cl2]Cl, observa-se valores mais negativos (-655 mV) no segundo complexo, sugerindo uma maior doa??o eletr?nica ao centro met?lico neste complexo o que pode ser atribu?do a uma maior proximidade dos ?tomos de nitrog?nio da etilenodiamina em rela??o a liga??o metal nitrog?nio do cyclam, devido ao efeito do ajuste do anel macroc?clico ao centro met?lico (efeito macroc?clico), o que faz com que a liga??o metal-nitrog?nio n?o seja t?o pr?xima quanto da etilenodiamina, fato que difere os ligantes em estudo. Comportamento similar ? tamb?m observado para os complexos, em que os cloretos s?o substitu?dos pelo ligante tiossulfato, trans-Na[Co(en)2(tios)2] (-640 mV) e trans- Na[Co(cyclam)(tios)2] (- 376 mV). Na espectroscopia de absor??o na regi?o do UVvis?vel observa-se a banda de transfer?ncia de carga LMCT (pdo ligante d* do metal), como sendo a de maior comprimento de onda para o trans- Na[Co(cyclam)(tios)2] (350 nm, ptios d* Co3+) e trans-Na[Co(en)2(tios)2] (333 nm, ptios d* Co3+) comparativamente ao complexo precursor, trans- [Co(cyclam)Cl2]Cl (318 nm, pCl- d* Co3+) indicando uma maior facilidade de transfer?ncia de densidade eletr?nica para o metal nos complexos com o ligante tiossulfato. Na an?lise de infravermelho observou-se a coordena??o do ligante tiossulfato ao metal nos complexos atrav?s de bandas na regi?o de 620-635 cm-1, caracter?sticas que comprovam a forma monodentada de coordena??o via ?tomo de enxofre e a perman?ncia das bandas νN-H para complexos com etilenodiamina, bandas em 3283 e 3267 cm-1, e complexos com o cyclam, bandas em 3213 e 3133 cm-1. Na an?lise de luminesc?ncia foi observada uma banda de transfer?ncia de carga em 397 nm e bandas d-d no espectro de emiss?o do complexo trans-Na[Co(cyclam)(tios)2] em 438, 450, 467, 481 e 492 nm.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-09T19:05:35Z No. of bitstreams: 1 GenicksonBorgesDeCarvalho_TESE.pdf: 3453614 bytes, checksum: 743ed6733d7ceea514e2575e4ec2eabf (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-10T21:24:30Z (GMT) No. of bitstreams: 1 GenicksonBorgesDeCarvalho_TESE.pdf: 3453614 bytes, checksum: 743ed6733d7ceea514e2575e4ec2eabf (MD5) / Made available in DSpace on 2017-03-10T21:24:30Z (GMT). No. of bitstreams: 1 GenicksonBorgesDeCarvalho_TESE.pdf: 3453614 bytes, checksum: 743ed6733d7ceea514e2575e4ec2eabf (MD5) Previous issue date: 2016-07-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / No presente trabalho ? descrito a s?ntese e a caracteriza??o dos compostos de coordena??o entre os nitratos de lantan?deos (III) e a pirazinacarboxamida (PyZ), visando uma poss?vel aplica??o funcional desses novos compostos como dispositivos moleculares conversores de luz. Os complexos obtidos foram caracterizados por meio de diversas t?cnicas anal?ticas, das quais podemos destacar: an?lise elementar, condutividade eletrol?tica molar, termogravimetria (TG) e an?lise t?rmica diferencial (DTA) simult?nea, calorimetria explorat?ria diferencial (DSC), espectroscopia de absor??o no infravermelho m?dio (FT-IR), espectroscopia por energia dispersiva de raios-X (EDS), difratometria de raios-X (DRX) pelo m?todo do p?, espectroscopia de absor??o eletr?nica (UV-Vis) a 298 K e espectroscopia de luminesc?ncia a 298 K. Atrav?s dos resultados de an?lise elementar, termogravimetria e de condutividade eletrol?tica molar, foi poss?vel propor as seguintes f?rmulas moleculares: [Ln(PyZ)2(NO3)2]NO3.2H2O (Ln3+ = La?Eu) e [Ln(PyZ)2(NO3)2]NO3.H2O (Ln3+ = Gd?Dy). As curvas TG-DTA e DSC forneceram informa??es a respeito da desidrata??o, degrada??o, estabilidade e natureza dos eventos t?rmicos referentes aos processos de decomposi??o. Os dados de condutividade, tanto em nitrometano como em acetonitrila, sugeriram comportamento de eletr?lito 1:1 para todos os compostos, refor?ando os resultados dos espectros de absor??o na regi?o do infravermelho m?dio, que indicaram a presen?a de nitrato n?o coordenado aos ?ons met?licos. Nos espectros eletr?nicos no UV-Vis observou-se o deslocamento das bandas de absor??o dos complexos estudados, quando comparadas ?s bandas do ligante livre, sugerindo a coordena??o do ?on met?lico central com o ligante pirazinacarboxamida. A an?lise dos espectros de absor??o na regi?o do infravermelho (FT-IR) permitiram estabelecer que os s?tios de coordena??o do ligante PyZ com o ?on met?lico s?o o oxig?nio carbon?lico e o nitrog?nio ? do anel piraz?nico. A interpreta??o dos difratogramas de raios-X revelou a exist?ncia de tr?s s?ries isom?rficas: a primeira compreende os compostos de La3+ e Ce3+, a segunda os compostos de Pr3+ ao Tb3+ e a terceira ao composto de Dy3+. O estudo das bandas hipersensitivas do complexo de neod?mio no estado s?lido a 298 K permitiu determinar os par?metros espectrosc?picos, cujos valores num?ricos indicam que a intera??o metal-ligante ? essencialmente eletrost?tica. A partir dos espectros eletr?nicos obtidos em solu??o de acetonitrila e etanol calculou-se a for?a do oscilador (P), cujos valores sugerem uma maior influ?ncia do etanol na esfera de coordena??o do ?on Nd3+. O espectro de emiss?o do complexo de gadol?nio revelou que a energia do estado tripleto excitado do ligante PyZ, encontra-se acima dos n?veis emissores dos ?ons Eu e Tb, o que favorece o processo de transfer?ncia de energia metal-ligante. Baseando-se na an?lise do espectro de emiss?o do composto de eur?pio no estado s?lido a 298 K, foi poss?vel atribuir uma microssimetria aproximadamente D2d, consistente com a geometria de um dodecaedro distorcido para o composto. A an?lise de luminesc?ncia sugere que os complexos de Eu3+, Tb3+, Sm3+ e Dy3+ apresentam emiss?es caracter?sticas na regi?o dos ?ons lantan?deos, por?m, quando em solu??o de acetonitrila, apenas o complexo de sam?rio n?o apresentou emiss?o na regi?o do vis?vel por ter possivelmente sua luminesc?ncia suprimida pela presen?a do solvente. / This present work describes the synthesis and characterization of coordination compounds between lanthanide nitrate (III) and pyrazinecarboxamide (PyZ), intending a possible functional application of these new compounds as molecular light conversion devices. The obtained compounds were characterized by various analytical techniques, of which we highlight: elemental analysis, molar electrolytic conductivity, thermogravimetry (TG) and differential thermal analysis (DTA) simultaneous, differential scanning calorimetry (DSC), absorption spectroscopy in mid infrared (FT-IR) spectroscopy by energy dispersive Xray (EDS), diffraction X-ray (XRD) by the powder method spectroscopy electronic absorption (UV-Vis) at 298 K and luminescence spectroscopy at 298 K. From the results of elemental analysis, thermogravimetry and molar electrolytic conductivity, it was possible to propose the following molecular formulas: [Ln(PyZ)2(NO3)2]NO3.2H2O (Ln3+ = La-Eu) and [Ln(PyZ)2 (NO3)2]NO3.H2O (Ln3+ = Gd-Dy). The TG-DTA and DSC curves provided information about dehydration, degradation, stability and nature of thermal events related to decomposition processes. The conductivity data, both nitromethane and acetonitrile, suggested an electrolyte behavior 1:1 for all compounds, reinforcing the results of the absorption spectra in the middle infrared region, which indicated the presence of nitrate is not coordinated to the metal ions. Regarding the electronic spectra UV-Vis, it was observed displacement of the absorption bands of the studied complexes, when compared to the free ligand bands, suggesting the coordination of the central metal ion with the binder pyrazinecarboxamide. The analysis of absorption spectra in the infrared (FT-IR) leads to stabilish that sites of coordination with the PyZ binder metal ion are carbonyl oxygen and nitrogen ? pyrazine ring. The interpretation of X-ray diffraction revealed the existence of three isomorphic series: the first comprises those compounds of La3+ and Ce3+, the second compounds of the Pr3+, Tb3+ and Dy3+ to the third compound. The study of hipersensitivas bands of neodymium complex in the solid state at 298 K allowed the determination of spectroscopic parameters, numerical values which indicate that metal-ligand interaction is essentially electrostatic. The oscillator strength (P) was calculated from the electronic spectra in acetonitrile solution and ethanol. The P values suggest a greater influence of ethanol in coordination ion Nd3+ ball. The emission spectrum of the gadolinium complex showed that the energy of the excited triplet state PyZ binder is between the emitting level of the Tb ions and I, which favors the process of metal-ligand energy transfer. Based on the analysis of the europium compound emission spectrum in the solid state at 298 K, it was possible to assign a microssimetria approximately D2d, consistent with the geometry of a distorted dodecahedron for the compound. Luminescence analysis suggests that the complexes of Eu3+, Tb3+, Sm3+ and Dy3+ display characteristic emissions in the region of lanthanide ions, however, when in acetonitrile solution, only samarium complex showed no emission in the visible region, probaly because a suppression of luminescence by the presence of the solvent.

Made available in DSpace on 2014-12-17T15:41:42Z (GMT). No. of bitstreams: 1 RoseaneSO.pdf: 1884603 bytes, checksum: 9b9e3631718ab941c6e9125f7deb26e8 (MD5) Previous issue date: 2007-08-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Films of chitosan with trivalent lanthanides ions Eu3+ and Tb3+ were respectively prepared in the ratio of 3:1 m/m (chitosan: lanthanide) and 6:1 m/m (chitosan: lanthanide). There were no formations of films in a ratio of 1:1 m/m (chitosan: lanthanides). The films of chitosan with the Tb3+ ion have the same transparent appearance than the pure chitosan films. The film of chitosan with Eu3+ ion has a muddy appearance. These films present good resistance to tear. The appearance of the compounds prepared in ratio 1:1m/m is a white powder. The films and compounds of chitosan were characterized by Elementary Analysis (CHN), Thermal Analysis (TG/DTG) and Spectroscopy of Luminescence. The CHN analysis was made only for compounds prepared in ratio 1:1m/m, suggesting that these compounds possess the formula QUILn.6H2O, where QUI = Chitosan and Ln = Lanthanide. The results of the curves TG/DTG indicated that there are strong interactions between Eu3+ or Tb3+ and chitosan, causing a lesser lost of mass in the films. The luminescence analysis showed that the films of chitosan with the ions Eu3+ and Tb3+ present emissions in the region of the visible one, with bands of the chitosan and of the Eu3+ ion. The luminescence analysis of the compounds of chitosan with the Eu3+ and Tb3+ ions suggest that the chitosan does not transfer into energy to the ions lanthanides, however the chemical neighborhood around of the ion lanthanides breaks the selection rules and, conseq?ently the 4f-4f transitions of the lanthanide ions are observed / Filmes de quitosana com os ?ons lantan?deos trivalentes Eu3+ e Tb3+ foram preparados na propor??o de 3:1 m/m (quitosana: lantan?deo) e 6:1 m/m (quitosana: lantan?deo), respectivamente. Na propor??o 1:1 m/m (quitosana: lantan?deo) n?o houve forma??o de filmes. Os filmes de quitosana com o ?on Tb3+ t?m uma apar?ncia similar ao filme de quitosana pura, mostrando-se transparente. J? o filme de quitosana com o ?on Eu3+ tem uma apar?ncia um pouco turva. Esses filmes apresentaram boa resist?ncia ao rasgo. Os compostos preparados na propor??o 1:1 formaram um s?lido em p? de cor branca. Tanto os filmes como os compostos de quitosana foram caracterizados por An?lise Elementar (CHN), An?lise T?rmica (TG/DTG) e Espectroscopia de Luminesc?ncia. As an?lise de CHN foram feitas apenas para os compostos de quitosana em p?, sugerindo que esses compostos possuem f?rmula geral QUILn.6H2O, onde QUI = Quitosana e Ln = Lantan?deo. Os resultados das curvas TG/DTG indicam que a introdu??o desses metais na estrutura da quitosana deixa suas liga??es mas fortes, tendo menor perda de massa nos filmes. A an?lise de luminesc?ncia mostrou que os filmes de quitosana com ?on Eu3+ e Tb3+ apresentam emiss?o na regi?o do vis?vel, com bandas referentes ? quitosana e ao ?on Eu3+. Para os compostos de quitosana em p? com os ?ons Eu3+ e Tb3+, a an?lise de luminesc?ncia sugere que a quitosana n?o est? transferindo energia para o ?on lantan?deo, no entanto a vizinhan?a qu?mica onde se encontra o ?on lantan?deo quebra as regras de sele??o e favorecem a emiss?o desses ?ons

Made available in DSpace on 2014-12-17T15:42:28Z (GMT). No. of bitstreams: 1 RoseaneSO_TESE.pdf: 2833413 bytes, checksum: cb4d0597d5a75ea4dc574237866165c1 (MD5) Previous issue date: 2013-07-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This is a work involving fundamental studies of chemistry where the synthesis and structural characterization, as well as a possible future application of these new compounds as luminescent sensors or sunscreen agents, complexes with 4,4 diaminostilbene-2,2-disulfonic (DSD) and trivalent lanthanide ions La3+, Nd3+, Eu3+, Gd3+ and Yb3+, were synthesized in the ratio of 3 mmol: 1 mmol (DSD: lanthanides). The complexes obtained with these ions were present in powder form and were characterized by complexometric titration with EDTA CHN Elemental analysis, molecular absorption spectroscopy in the ultraviolet region, the absorption spectroscopy in the infrared, thermal analysis (TG / DTG), Nuclear Magnetic Resonance - NMR 1H and Luminescence Spectroscopy. The complexometric titration and CHN analysis, confirmed the TG / DTG which suggest that these complexes have the following general chemical formulas: [La2(C14H12S2O6N2)2(H2O)2Cl2].7H2O,[Nd2(C14H12S2O6N2)2(H2O)2Cl2].6H2O,[Eu2(C14 H12S2O6N2)2(H2O)2Cl2].7H2O,[Gd2(C14H12S2O6N2)2(H2O)2Cl2].4H2O e [Yb2(C14H12S2O6N2)2(H2O)2].6H2O. The disappearance of the bands in the infrared spectrum at 2921 cm-1 and 2623 cm-1 and the displacement of the bands in the spectra of the amine complex indicate that the lanthanide ion is coordinated to the oxygen atoms and the sulfonate groups of the nitrogens amines, suggesting the formation of the dimer. The disappearance of the signal and the displacement signal SO3H amines in the 1H NMR spectrum of this complex are also indicative coordination and dimer formation. The Thermogravimetry indicates that the DSD is thermally stable in the range of 40? to 385?C and their complexes with lanthanide ions exhibit weight loss between 4 and 5 stages. The Uv-visible spectra indicated that the DSD and complexes exhibit cis isomers. The analysis of luminescence indicates that the complexes do not exhibit emission in the region of the lanthanides but an intense emission part of the binder. This is related to the triplet states of the ligand, which are in the lowest energy state emitting lanthanide ions, and also the formation of the dimer that suppress the luminescence of ion Eu3+. The formation of dimer was also confirmed by calculating the europium complex structure using the model Hamiltonian PM6 and Sparkle / Visando um trabalho de estudos fundamentais da qu?mica, envolvendo a s?ntese e caracteriza??o estrutural, assim como uma poss?vel aplica??o futura desses novos compostos como sensores luminescentes ou agentes de prote??o solar, foram sintetizados os complexos com o ?cido 4,4-diaminoestilbeno-2,2-disulf?nico (DSD) e os ?ons lantan?deos trivalentes La3+, Nd3+, Eu3+, Gd3+ e Yb3+, preparados na propor??o de 3 mmol: 1mmol (DSD: Lantan?deos). Os complexos obtidos com esses ?ons apresentaram-se na forma de p? e foram caracterizados por: Titula??o Complexom?trica com EDTA, An?lise Elementar de CHN, Espectroscopia de Absor??o Molecular na Regi?o do Ultravioleta, Espectroscopia de Absor??o na Regi?o do Infravermelho, An?lise T?rmica (TG/DTG), Resson?ncia Magn?tica Nuclear RMN-1H e Espectroscopia de Luminesc?ncia. A titula??o complexom?trica e a an?lise de CHN, com confirma??o da TG/DTG, sugerem que esses complexos possuem as seguintes f?rmulas qu?micas gerais: [La2(C14H12S2O6N2)2(H2O)2Cl2].7H2O, [Nd2(C14H12S2O6N2)2(H2O)2Cl2].6H2O, [Eu2(C14H12S2O6N2)2(H2O)2Cl2].7H2O, [Gd2(C14H12S2O6N2)2(H2O)2Cl2].4H2O e [Yb2(C14H12S2O6N2)2(H2O)2].6H2O. O desaparecimento das bandas, no espectro de Infravermelho, em 2921 cm-1 e 2623 cm-1 e o deslocamento das bandas da amina nos espectros dos complexos indicam que a coordena??o ao ?on lantan?deo ocorre atrav?s dos oxig?nios dos grupos sulfonatos e pelos nitrog?nios das aminas, sugerindo a forma??o do d?mero. O desaparecimento do sinal SO2O-H e o deslocamento do sinal das aminas no espectro de RMN-1H dos complexos s?o tamb?m indicativos dessa coordena??o e da forma??o do d?mero. A an?lise t?rmica indica que o DSD ? termicamente est?vel no intervalo de 40?C at? 385?C e que os seus complexos com os ?ons lantan?deos apresentam perda de massa entre 4 e 5 etapas. Os espectros de Uv-Vis?vel indicam que DSD e os complexos apresentam isomeria cis. A an?lise de luminesc?ncia indica que os complexos n?o apresentam emiss?o na regi?o dos ?ons lantan?deos, mas sim uma emiss?o intensa da parte do ligante. Isso est? relacionado com os estados tripletos do ligante, que est?o em energia mais baixa que o estado emissor dos ?ons lantan?deos, e tamb?m com a forma??o do d?mero que suprime a luminesc?ncia do ?on Eu3+. A forma??o do d?mero tamb?m foi confirmada atrav?s do c?lculo da estrutura do complexo de eur?pio, utilizando o modelo Sparkle e hamiltoniano PM6, que mostrou um ponto de m?nimo na superf?cie de energia potencial desta esp?cie

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-02-22T22:19:59Z No. of bitstreams: 1 DavidLinoVasconcelos_DISSERT.pdf: 10972209 bytes, checksum: 92858ff8a60fdac09332f5f0467e6fe3 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-02-25T19:54:57Z (GMT) No. of bitstreams: 1 DavidLinoVasconcelos_DISSERT.pdf: 10972209 bytes, checksum: 92858ff8a60fdac09332f5f0467e6fe3 (MD5) / Made available in DSpace on 2016-02-25T19:54:57Z (GMT). No. of bitstreams: 1 DavidLinoVasconcelos_DISSERT.pdf: 10972209 bytes, checksum: 92858ff8a60fdac09332f5f0467e6fe3 (MD5) Previous issue date: 2014-02-26 / Na regi?o litor?nea do Cear?, entre os munic?pios de Acara? e Itapipoca, foram identificados treze s?tios contendo indicadores do n?vel relativo do mar, sendo seis destes datados por luminesc?ncia opticamente estimulada (LOE) e radiocarbono. As idades obtidas suportam que foram formadas praias progradantes na ?rea de estudo. Na parte oriental, ocorrem praias em dep?sitos de plan?cie costeira, enquanto que um sistema laguna/barreira com paleomanguezais ocorre na parte ocidental da ?rea de estudo. Em ambos os casos os dep?sitos costeiros progradam de leste para oeste. Foram identificados n?veis de mar mais alto que o atual entre: (a) 3.110-2.830 anos cal. AP; (b) 1.830 anos AP (LOE) - 1.490 anos cal. AP; (c) entre 1.240-1.060 anos cal. AP; (d) 845- 715 anos AP (LOE). Desde ent?o o n?vel do mar sofreu um abaixamento at? o n?vel atual. As varia??es do n?vel do mar s?o interpretadas como respostas a altera??es no padr?o de circula??o marinha e n?o exclu?mos poss?veis perturba??es tect?nicas na bacia da margem continental. Os indicadores do n?vel relativo do mar para litoral oeste do Cear? apresentam-se diferente das outras curvas constru?das no litoral do nordeste, sugerindo que os fatores locais citados acima contribu?ram para flutua??es do n?vel do mar. / In the coastal region of Cear?, between the municipalities of Acara? and Itapipoca, thirteen sites were identified containing indicators of relative sea level, six of these being dated by optically stimulated luminescence (OSL) and radiocarbon. Ages obtained supports that were formed prograding beaches in the study area. In the eastern portion, beaches in coastal plain deposits occur while a system lagoon/barrier paleomangrove occurs in the western portion of the study area. In both cases the coastal deposits prograde from east to west. Higher sea levels were identified between the current: (a) 3.110-2.830 cal. yr. BP; (b) 1.830 yr. BP (OSL) - 1.490 cal. yr. BP; (c) between 1.240-1.060 cal. yr. BP; (d) 845-715 yr. BP (OSL). Since then the sea level suffered by lowering the current level. Variations in sea level are interpreted as responses to changes in the pattern of marine circulation and do not exclude possible tectonic disturbances in the basin of the continental margin. The indicators of relative sea level west coast of Cear? present differently from other curves constructed in the coastal northeast, suggesting that local factors mentioned above contributed to sea level fluctuations.