Структурні особливості комплексоутворення на поверхні : автореферат дисертації на здобуття наукового ступеня доктора хімічних наук
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Date
2002
Authors
Голуб, О. А.
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Abstract
Дисертація присвячена дослідженню впливу прищеплення до поверхні, структури поверхні та лігандного шару на протолітичні і координаційні рівноваги, а також на будову утворюваних координаційних сполук. На прикладі великого числа вперше синтезованих координаційних сполук перехідних металів з іммобілізованими на поверхні аеросилу фосфатними, тіофосфатними, бі- та амнолідентатними азометиновими лігандами демонструються можливості застосування молекулярного моделювання (методи молекулярної механіки, квантової хімії, математичної статистики) для прогнозування складу та будови
прищеплених комплексів, а також сорбційних властивостей адсорбентів. Розглядаються можливості застосування синтезованих сполук як каталізаторів та селективних сенсорів.
The thesis is devoted to investigation of anchoring to surface, ligands layer and surface structure influence on protolytic and complex formation equilibrium so as on formed coordination compounds structure. By means of formal thermodynamics it is shown that the reactions of the complex formation, which proceed on a silica surface have a number of distinctive features in comparison with similar reactions in solutions. Among them we can mention (i) the simultaneous formation of several kinds of superficial compounds, (ii) the lowering of basicity of immobilised ligands in comparing with free ones, (iii) the dependence of the stability of complexes on the degree of completeness of the reaction, as well as on the topology of immobilized ligands, (iv) the influence of excess of free electrostatic energy of a surface as a result of electric double layer formation and so on. One of the main factors, influencing complex formation is the structure of ligand cover, namely, arrangement and donor centers structural features. It is shown that major and frequently unique information may give molecular modeling (MM) of superficial ligands and their complexes. In difference from similar systems in solutions the application of theoretical methods for studying of coordination compounds at the solid surface seems to be especially attractive because of the rigidity of the support for this reduce the number of freedom degrees of the molecules and the number of spatial configurations to be analyzed. In thesis by meens of MM is shown an impossibility of hydrogen bonding formation between amino groups themselves and amino groups and silanols at plane regular aminopropylaerosil surface. In frames of simple geometrical model the peculiarities of hemosorbed molecules concentration dependence from their size, specific surface area and spacer length have been determined. Obtained analytical correlation permit to forecast a nonlinearity in the dependence between adsorbed molecules concentration and specific surface area which can exceed 20% at 1.7 times surface area changing, and allow ligands effective size to be estimated from experimental data for similar molecules at adsorbent surfaces of different surface area. In thesis the possibilities of athematical statistic methods for prediction of adsorption properties of complexing sorbents is discussed. As shown by the computational methods at the surface of nonporous silica metal-ions can bind only one structural silanol group. The complexes are bond with isolated silanols irrespective of the way of synthesis, - as in the case of ion exchange, by reaction of impregnation with salt solutions and the subsequent thermal decomposition. The formation regularity of metal oxide surface layer at aerosil is analysed. For silica, containing anchored phosphate or tiophosphate groups connected with a surface through silanols, molecular mechanic and the quantum chemistry predict primary stability of complexes of a structure 1:1 in the case of bidentate linkage with a metal. This linkage is the most characteristic for hard acids like RE metals. Such forecast is confirmed by NMR "P and 'll data. The linkage with two phosphate groups is possible for metals, which coordinate phosphate-ions monodentatly. Flexible hydrocarbon skeleton permits for small mono and bidentate ligands to form complexes with coordination up to three surface groups, though more often, because of steric restrictions only two immobilized ligands are coordinated. In case of large bidentate ligands, at their close filling, specific cavities selectively bonding metal-ions can be formed. So immobilized Shiff bases like salyciial derivative azomethines as shown by calculated and spectroscopic data, predominantly form tetrahedral complexes with metal ions, which prefer tetrahedral surroundings and trigonal bipyramid for vanadyl ion. In the case of large steric hindered ampoiydentate ligands with several centers of coordination it is possible to coordinate only one metal ion to one ligand. And, in the case of different metals, each of them chooses the most suitable position, or donor center. Especially it is interesting for luminescent ligands with considerably distinguished donor centers. In such case the luminescence spectra depend on a place of coordination, and on a chemical nature of a metal. For the biscrown azomethine it is found high selective fluorescent sensor properties to lantanum. In thesis the catalytic activity of some immobilised azomethine complexes in ozone cjecomposition reaction is discovered and investigated.
Диссертация посвящена исследованию влияния прививки к поверхности, структуры поверхности и лигандного слоя на протолитические и координационные равновесия, а также на строение, образующихся координационных соединений. На примере большого числа впервые синтезированных координационных соединений переходных металлов с иммобилизованными на поверхности аэросила фосфатными, тиофосфатными, би- и амполидентатными азометиновыми лигандами демонстрируются возможности применения молекулярного моделирования (методы молекулярной механики, квантовой химии, математической статистики) для прогнозирования состава и строения привитых комплексов, а также сорбционных свойств адсорбентов. Рассматриваются возможности использования синтезированных соединений как катализаторов и селективных сенсоров.
The thesis is devoted to investigation of anchoring to surface, ligands layer and surface structure influence on protolytic and complex formation equilibrium so as on formed coordination compounds structure. By means of formal thermodynamics it is shown that the reactions of the complex formation, which proceed on a silica surface have a number of distinctive features in comparison with similar reactions in solutions. Among them we can mention (i) the simultaneous formation of several kinds of superficial compounds, (ii) the lowering of basicity of immobilised ligands in comparing with free ones, (iii) the dependence of the stability of complexes on the degree of completeness of the reaction, as well as on the topology of immobilized ligands, (iv) the influence of excess of free electrostatic energy of a surface as a result of electric double layer formation and so on. One of the main factors, influencing complex formation is the structure of ligand cover, namely, arrangement and donor centers structural features. It is shown that major and frequently unique information may give molecular modeling (MM) of superficial ligands and their complexes. In difference from similar systems in solutions the application of theoretical methods for studying of coordination compounds at the solid surface seems to be especially attractive because of the rigidity of the support for this reduce the number of freedom degrees of the molecules and the number of spatial configurations to be analyzed. In thesis by meens of MM is shown an impossibility of hydrogen bonding formation between amino groups themselves and amino groups and silanols at plane regular aminopropylaerosil surface. In frames of simple geometrical model the peculiarities of hemosorbed molecules concentration dependence from their size, specific surface area and spacer length have been determined. Obtained analytical correlation permit to forecast a nonlinearity in the dependence between adsorbed molecules concentration and specific surface area which can exceed 20% at 1.7 times surface area changing, and allow ligands effective size to be estimated from experimental data for similar molecules at adsorbent surfaces of different surface area. In thesis the possibilities of athematical statistic methods for prediction of adsorption properties of complexing sorbents is discussed. As shown by the computational methods at the surface of nonporous silica metal-ions can bind only one structural silanol group. The complexes are bond with isolated silanols irrespective of the way of synthesis, - as in the case of ion exchange, by reaction of impregnation with salt solutions and the subsequent thermal decomposition. The formation regularity of metal oxide surface layer at aerosil is analysed. For silica, containing anchored phosphate or tiophosphate groups connected with a surface through silanols, molecular mechanic and the quantum chemistry predict primary stability of complexes of a structure 1:1 in the case of bidentate linkage with a metal. This linkage is the most characteristic for hard acids like RE metals. Such forecast is confirmed by NMR "P and 'll data. The linkage with two phosphate groups is possible for metals, which coordinate phosphate-ions monodentatly. Flexible hydrocarbon skeleton permits for small mono and bidentate ligands to form complexes with coordination up to three surface groups, though more often, because of steric restrictions only two immobilized ligands are coordinated. In case of large bidentate ligands, at their close filling, specific cavities selectively bonding metal-ions can be formed. So immobilized Shiff bases like salyciial derivative azomethines as shown by calculated and spectroscopic data, predominantly form tetrahedral complexes with metal ions, which prefer tetrahedral surroundings and trigonal bipyramid for vanadyl ion. In the case of large steric hindered ampoiydentate ligands with several centers of coordination it is possible to coordinate only one metal ion to one ligand. And, in the case of different metals, each of them chooses the most suitable position, or donor center. Especially it is interesting for luminescent ligands with considerably distinguished donor centers. In such case the luminescence spectra depend on a place of coordination, and on a chemical nature of a metal. For the biscrown azomethine it is found high selective fluorescent sensor properties to lantanum. In thesis the catalytic activity of some immobilised azomethine complexes in ozone cjecomposition reaction is discovered and investigated.
Диссертация посвящена исследованию влияния прививки к поверхности, структуры поверхности и лигандного слоя на протолитические и координационные равновесия, а также на строение, образующихся координационных соединений. На примере большого числа впервые синтезированных координационных соединений переходных металлов с иммобилизованными на поверхности аэросила фосфатными, тиофосфатными, би- и амполидентатными азометиновыми лигандами демонстрируются возможности применения молекулярного моделирования (методы молекулярной механики, квантовой химии, математической статистики) для прогнозирования состава и строения привитых комплексов, а также сорбционных свойств адсорбентов. Рассматриваются возможности использования синтезированных соединений как катализаторов и селективных сенсоров.
Description
Keywords
комплексоутворення на поверхні, координаційні сполуки, іммобілізовані ліганди, поверхня, аеросил, молекулярне моделювання, каталізатори, сенсори, автореферат дисертації, complex formation, coordination compounds, immobilized ligands, surface, aerosil, molecular modeling, catalysts, sensors, комплексообразование на поверхности, координационные соединения, иммобилизованные лиганды, поверхность, аэросил, молекулярное моделирование, катализаторы, сенсоры
Citation
Голуб О., Структурні особливості комплексоутворення на поверхні : автореферат дисертації на здобуття наукового ступеня доктора хімічних наук / Голуб Олександр Андрійович ; Київський національний університет ім. Тараса Шевченка. - Київ : [б. в.], 2002. - 33 с. : іл., табл.