Publicação
Synthesis and characterization of heterocyclic compounds and modified amino acids with application in nonlinear optics and/or as fluorimetric and colorimetric sensors for anions and cations
| Resumo: | For the last two decades donor-acceptor substituted heterocyclic compounds have attracted widespread interest due to their exceptional optical properties, high thermal and chemical stability, and good transparency, as well as easy synthesis. Earlier studies demonstrated that they are strong candidates for use in several optoelectronic applications such as data storage communication, solvatochromic and fluorescent probes, nonlinear optical (NLO) materials and organic light emitting diodes (OLEDs). These technological applications motivated the present investigation, leading to the design and synthesis of new materials. The development of artificial receptors for the sensing and recognition of environmentally and biologically important ionic species is also currently of great interest. Highly selective anion or cation sensing is imperative for many areas, including environmental, biological, clinical, and waste management applications. Chemical sensors based on heterocyclic units are unique and useful for abiotic or biological recognition because, being generally highly fluorescent and having a very high capacity for electronic transfer, with the possibility of acting both as the recognition and signaling unit. Such heterocyclic moieties were combined with amino acid cores, resulting in unnatural amino acids that were reported as fluorescent biomarkers and colorimetric and/or fluorometric sensors of anions and cations. The work presented in this thesis reports the synthesis and characterization of heterocyclic compounds and heterocycle-based amino acid derivatives as well as the evaluation of their photophysical and thermal properties having in mind their potential application as nonlinear optical compounds, OLEDs, fluorescent probes and colorimetric or fluorimetric chemosensors for anions and cations. Several series of novel thermally stable second-order nonlinear optical (NLO) heterocyclic systems have been designed and synthesized from easily available precursors and low cost commercially available reagents, using simple and convenient synthetic and purification procedures. Different combinations of donor groups (alkoxyl, N,N-dialkylamino, etc.), -conjugated bridges (arylthiophene, oligothiophene and thienylpyrrole), and acceptor moieties (thiobarbituric acid, indanonedicyanovinyl, anthraquinone, benzimidazole, benzothiazole, phenanthroline) were studied in order to obtain more efficient NLO systems. The novel compounds were completely characterized by the usual characterization techniques (mass spectrometry, proton and carbon nuclear magnetic resonance spectroscopy, infrared spectroscopy and elemental analysis). The photophysical properties of the novel derivatives (absorption in the ultraviolet-visible and fluorescence) were also studied, while hyper-Rayleigh scattering (HRS) and thermogravimetric analysis (TGA) were employed to evaluate their nonlinear optical properties (determination of ), and their thermal stability, respectively. For some compounds the theoretical investigation by Density Functional Theory (DFT), of the ground- and singlet excited state optimized geometries were also studied. This multidisciplinary study showed that these heterocyclic systems have good second-order molecular NLO activity, good thermal stabilities and interesting fluorescent properties making them interesting candidates as prospective second-order NLO and OLEDs materials. Secondly, several series of heterocyclic systems (imidazo-anthraquinones, imidazophenanthrolines, bis-indolylmethanes and crown ethers) bearing arylthienyl, oligothienyl, arylfuryl and thienylfuryl -bridges were synthesized and fully characterized. The interaction studies of these novel systems with a large diversity of anions and cations with analytical, environmental or medicinal relevance was performed by absorption and emission spectroscopy showing that they could be used as selective colorimetric and/or fluorimetric chemosensors with high selectivity for some anions (OH-, F-, CN-, AcO-) and cations (Ni2+,Ca2+, Cu2+, Hg2+, Zn2+, Pd2+). Unnatural amino acids (alanines and phenylalanines), bearing heterocyclic moieties (benzoxazole and benzimidazole) were also synthesized and fully characterized. The evaluation of the chemosensory properties of these novel amino acids revealed that they could be used as fluorimetric or colorimetric chemosensors for OH-, F- and Pd2+. Moreover, the evaluation of the photophysical properties of alanine derivatives revealed that they display exceptionally high fluorescence quantum yields, making them good candidates for application as fluorescent probes. Finally, thienyl- and furyl-imidazo-phenanthrolines were used as ligands for the synthesis of Ru2+ polypiridyl complexes. Studies of their interaction with DNA have suggested a partial intercalation of the probes into the nucleic acid double strand. |
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| Autores principais: | Batista, Rosa Maria Ferreira |
| Ano: | 2011 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | For the last two decades donor-acceptor substituted heterocyclic compounds have attracted widespread interest due to their exceptional optical properties, high thermal and chemical stability, and good transparency, as well as easy synthesis. Earlier studies demonstrated that they are strong candidates for use in several optoelectronic applications such as data storage communication, solvatochromic and fluorescent probes, nonlinear optical (NLO) materials and organic light emitting diodes (OLEDs). These technological applications motivated the present investigation, leading to the design and synthesis of new materials. The development of artificial receptors for the sensing and recognition of environmentally and biologically important ionic species is also currently of great interest. Highly selective anion or cation sensing is imperative for many areas, including environmental, biological, clinical, and waste management applications. Chemical sensors based on heterocyclic units are unique and useful for abiotic or biological recognition because, being generally highly fluorescent and having a very high capacity for electronic transfer, with the possibility of acting both as the recognition and signaling unit. Such heterocyclic moieties were combined with amino acid cores, resulting in unnatural amino acids that were reported as fluorescent biomarkers and colorimetric and/or fluorometric sensors of anions and cations. The work presented in this thesis reports the synthesis and characterization of heterocyclic compounds and heterocycle-based amino acid derivatives as well as the evaluation of their photophysical and thermal properties having in mind their potential application as nonlinear optical compounds, OLEDs, fluorescent probes and colorimetric or fluorimetric chemosensors for anions and cations. Several series of novel thermally stable second-order nonlinear optical (NLO) heterocyclic systems have been designed and synthesized from easily available precursors and low cost commercially available reagents, using simple and convenient synthetic and purification procedures. Different combinations of donor groups (alkoxyl, N,N-dialkylamino, etc.), -conjugated bridges (arylthiophene, oligothiophene and thienylpyrrole), and acceptor moieties (thiobarbituric acid, indanonedicyanovinyl, anthraquinone, benzimidazole, benzothiazole, phenanthroline) were studied in order to obtain more efficient NLO systems. The novel compounds were completely characterized by the usual characterization techniques (mass spectrometry, proton and carbon nuclear magnetic resonance spectroscopy, infrared spectroscopy and elemental analysis). The photophysical properties of the novel derivatives (absorption in the ultraviolet-visible and fluorescence) were also studied, while hyper-Rayleigh scattering (HRS) and thermogravimetric analysis (TGA) were employed to evaluate their nonlinear optical properties (determination of ), and their thermal stability, respectively. For some compounds the theoretical investigation by Density Functional Theory (DFT), of the ground- and singlet excited state optimized geometries were also studied. This multidisciplinary study showed that these heterocyclic systems have good second-order molecular NLO activity, good thermal stabilities and interesting fluorescent properties making them interesting candidates as prospective second-order NLO and OLEDs materials. Secondly, several series of heterocyclic systems (imidazo-anthraquinones, imidazophenanthrolines, bis-indolylmethanes and crown ethers) bearing arylthienyl, oligothienyl, arylfuryl and thienylfuryl -bridges were synthesized and fully characterized. The interaction studies of these novel systems with a large diversity of anions and cations with analytical, environmental or medicinal relevance was performed by absorption and emission spectroscopy showing that they could be used as selective colorimetric and/or fluorimetric chemosensors with high selectivity for some anions (OH-, F-, CN-, AcO-) and cations (Ni2+,Ca2+, Cu2+, Hg2+, Zn2+, Pd2+). Unnatural amino acids (alanines and phenylalanines), bearing heterocyclic moieties (benzoxazole and benzimidazole) were also synthesized and fully characterized. The evaluation of the chemosensory properties of these novel amino acids revealed that they could be used as fluorimetric or colorimetric chemosensors for OH-, F- and Pd2+. Moreover, the evaluation of the photophysical properties of alanine derivatives revealed that they display exceptionally high fluorescence quantum yields, making them good candidates for application as fluorescent probes. Finally, thienyl- and furyl-imidazo-phenanthrolines were used as ligands for the synthesis of Ru2+ polypiridyl complexes. Studies of their interaction with DNA have suggested a partial intercalation of the probes into the nucleic acid double strand. |
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