Monoporfirinatos dipolares basados en iones de tierras raras como prototipos de rotor molecular con respuesta óptica no lineal de segundo orden.
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Date
2024
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Universidad de Concepción
Abstract
La presente investigación se centra en la síntesis, caracterización, y estudio de una nueva clase de entidades de coordinación tecno-miméticas respecto a un rotor tipo hélice. Estos complejos monoporfirínicos se derivan de la combinación de iones de tierras raras, TR(III) donde TR= Yb, Er, Dy y Tb, y ligandos: “ancla” y auxiliares dipolares. Las propiedades estructurales y funcionales de estas arquitecturas moleculares han sido investigadas de manera sistemática para dilucidar sus posibles aplicaciones como rotores moleculares en superficie y cromóforos con respuesta óptica no lineal de segundo orden (ONL-2).
Para construir estas entidades de coordinación se sintetizaron ligandos bidentados basados en 1,3-dicetonas B1-B6, que sirvieron como bloques de construcción. Estos ligandos fueron funcionalizados con grupos electro donadores (D), -OCH3 y -OC12H25, y electro-aceptores (A), -CN y-CF3, terminales; para generar sistemas del tipo D--A o “push-pull”. A partir de estos compuestos, se sintetizaron ligandos tridentados bases de Schiff ONN SB1-SB5, mediante la condensación del grupo carbonilo de B1-B5 con 8 aminoquinolina.
Adicionalmente, se sintetizaron una nueva clase de compuestos de coordinación monoporfirínicos dipolares de TR(III), C1-M, C2-M y C3-M, empleando como ligandos auxiliares B2, B3 y B4, respectivamente. En este contexto, el análisis cristalográfico revelo que los compuestos C1-Yb, C1-Er, C1-Dy y C2-Yb, son isoestructurales caracterizado por un ambiente heptacoordinado. Estos complejos presentan una arquitectura molecular tecno-mimética con respecto a un rotor tipo hélice coincidiendo con la inspiración de diseño propuesto inicialmente. En esta configuración, el ligando -dicetónico o rotator, emula las aspas de la hélice del rotor, mientras que el catión lantánido trivalente TR(III), se asemeja a una bola de rodamiento o eje de rotación, conectando el ligando rotador con el macrociclo porfirínico o stator. Este arreglo estructural único presenta un comportamiento favorable para ser depositadas sobre superficies metálicas, como Au (111), inmovilizadas a través del ligando stator, y ser estudiado a escala molecular por la técnica Scanning Tunneling Microscopy (STM). Por otra parte, estas arquitecturas pueden formar redes moleculares, en estado sólido, organizadas por el momento dipolar del ligando auxiliar, permitiendo una comunicación intermolecular.
Finalmente, los complejos de coordinación C1-M y C2-M, donde M= Yb(III), Er(III), y Dy(III), se estudiaron mediante la técnica Hyper-Rayleigh Scattering o Harmonic Light Sattering (HLS) para determinar su respuesta ONL-2. Estos compuestos presentaron respuesta de hiperpolarizabilidad cuadrática () entre 100-200×10-30 esu. La magnitud de esta respuesta está significativamente influenciada por la naturaleza electrónica de los ligandos orgánicos y, predominantemente, por la configuración electrónica del centro metálico, que aporta contribución octupolar al valor de hiperpolarizabilidad obtenido. Cabe destacar que la actividad óptica varía directamente proporcional al número de electrones en la capa 4f del ion central, siendo los compuestos C1-Yb y C2-Yb (f13), los que presentan una mayor respuesta de Generación del Segundo Armónico (GSA).
El diseño innovador de estas arquitecturas moleculares abre el camino para la síntesis de sistemas de coordinación funcionales basados en monoporfirinatos de TR(III). La adaptabilidad de estos sistemas permite la modulación y mejora de la respuesta ONL-2, mediante la modificación de las propiedades electrónica de los sustituyentes en los ligandos 1,3-diaril-dicetona y meso-A4 porfirina, así como, la selección del ion lantánido (III). Además, al variar la denticidad del ligando auxiliar y la geometría de coordinación, es posible acceder a novedosas arquitecturas moleculares con potenciales aplicaciones ópticas, luminiscentes y magnéticas. Adicionalmente, la capacidad de estos compuestos de depositarse y ordenarse sobre superficies subraya su significativo potencial como componentes activos en dispositivos optoelectrónicos.
The current research focuses on the synthesis, characterization, and comprehensive study of a novel class of techno-mimetic coordination complexes that exhibit a propeller rotor-like architecture. These monoporphyrinate complexes are derived from rare earth ion TR(III), where TR = Yb, Er, Dy, and Tb, in conjunction with auxiliary dipolar ligands. The structural and functional properties of these entities have been systematically investigated to elucidate their potential applications as molecular rotor on surface and as active second-order nonlinear optic chromophore. The construction of these coordination complexes was achieved by synthesizing bidentate 1,3-diketone-based ligands B1-B6, which served as building blocks. These ligands were strategically functionalized with electron-donating (-DoO and -MeO) and electron-accepting groups (-CN and -CF3), to create D--A or "push-pull" systems. From these compounds, the synthesis of tridentate-ONN Schiff base ligands, SB1-SB5, was accomplished through the condensation of the carbonyl group of compounds B1-B5 with 8-aminoquinoline. Additionally, a new class of dipolar monoporphyrinic coordination compounds of TR(III), C1-M, C2-M y C3-M, was synthetized using B2, B3 and B4, as ancillary ligands, respectively. Crystallographic analysis revealed that compounds C1-Yb, C1-Er, C1-Dy, and C2-Yb share an isostructural geometry characterized by an heptacoordinated environment. These compounds exhibit a techno-mimetic molecular architecture that closely resembles a propeller rotor. In this configuration, the β-diketone or rotator ligand functions analogously to the blades of the rotor, while the trivalent lanthanide cation TR(III) serves as a ball bearing or rotational axis, linking the rotator ligand to the porphyrinic macrocycle or stator. This unique structural arrangement facilitates the deposition of these complexes onto metallic surfaces, such as Au (111), where they can be immobilized through the stator ligand. Such deposition allows for molecular-scale investigations using Scanning Tunneling Microscopy (STM). Furthermore, these complexes can form molecular networks, in the solid state, organized by the dipolar moment of the auxiliary ligand, enabling inter-molecular communication. Molecular architectures C1-M and C2-M, where M = Yb(III), Er(III), and Dy(III), were subjected to Hyper-Rayleigh Scattering (HLS) analysis to evaluate their second-order nonlinear optical (ONL-2) response. These complexes demonstrated quadratic hyperpolarizability (β) values ranging from 100 to 200 x 10-30 esu. The magnitude of this response is significantly influenced by the electronic characteristics of the organic ligands and, predominantly, by the electronic configuration of the metal center, which imparts an octupolar contribution to the hyperpolarizability value. Notably, the optical activity is directly proportional to the electron count within the 4f orbital of the central ion, with C1-Yb and C2-Yb (f13) displaying the most pronounced response. The innovative design of these molecular architectures paves the way for the synthesis of functional monoporphyrinic coordination systems of TR(III). The adaptability of these architectures permits the modulation and enhancement of the ONL-2 response through strategic alterations in the electronic properties of the substituents within the 1,3-diaryl-diketone and meso-A4-porphyrin ligands, as well as the selection of the lanthanide (III) ion. Furthermore, by varying the denticity of the ancillary ligand and coordination geometry, it is possible to access novel molecular architectures with potential optical, luminescent, and magnetic properties. In addition, the capacity of these compounds to be deposited and systematically arranged on surfaces underscores their significant potential as active components in advanced optoelectronic devices.
The current research focuses on the synthesis, characterization, and comprehensive study of a novel class of techno-mimetic coordination complexes that exhibit a propeller rotor-like architecture. These monoporphyrinate complexes are derived from rare earth ion TR(III), where TR = Yb, Er, Dy, and Tb, in conjunction with auxiliary dipolar ligands. The structural and functional properties of these entities have been systematically investigated to elucidate their potential applications as molecular rotor on surface and as active second-order nonlinear optic chromophore. The construction of these coordination complexes was achieved by synthesizing bidentate 1,3-diketone-based ligands B1-B6, which served as building blocks. These ligands were strategically functionalized with electron-donating (-DoO and -MeO) and electron-accepting groups (-CN and -CF3), to create D--A or "push-pull" systems. From these compounds, the synthesis of tridentate-ONN Schiff base ligands, SB1-SB5, was accomplished through the condensation of the carbonyl group of compounds B1-B5 with 8-aminoquinoline. Additionally, a new class of dipolar monoporphyrinic coordination compounds of TR(III), C1-M, C2-M y C3-M, was synthetized using B2, B3 and B4, as ancillary ligands, respectively. Crystallographic analysis revealed that compounds C1-Yb, C1-Er, C1-Dy, and C2-Yb share an isostructural geometry characterized by an heptacoordinated environment. These compounds exhibit a techno-mimetic molecular architecture that closely resembles a propeller rotor. In this configuration, the β-diketone or rotator ligand functions analogously to the blades of the rotor, while the trivalent lanthanide cation TR(III) serves as a ball bearing or rotational axis, linking the rotator ligand to the porphyrinic macrocycle or stator. This unique structural arrangement facilitates the deposition of these complexes onto metallic surfaces, such as Au (111), where they can be immobilized through the stator ligand. Such deposition allows for molecular-scale investigations using Scanning Tunneling Microscopy (STM). Furthermore, these complexes can form molecular networks, in the solid state, organized by the dipolar moment of the auxiliary ligand, enabling inter-molecular communication. Molecular architectures C1-M and C2-M, where M = Yb(III), Er(III), and Dy(III), were subjected to Hyper-Rayleigh Scattering (HLS) analysis to evaluate their second-order nonlinear optical (ONL-2) response. These complexes demonstrated quadratic hyperpolarizability (β) values ranging from 100 to 200 x 10-30 esu. The magnitude of this response is significantly influenced by the electronic characteristics of the organic ligands and, predominantly, by the electronic configuration of the metal center, which imparts an octupolar contribution to the hyperpolarizability value. Notably, the optical activity is directly proportional to the electron count within the 4f orbital of the central ion, with C1-Yb and C2-Yb (f13) displaying the most pronounced response. The innovative design of these molecular architectures paves the way for the synthesis of functional monoporphyrinic coordination systems of TR(III). The adaptability of these architectures permits the modulation and enhancement of the ONL-2 response through strategic alterations in the electronic properties of the substituents within the 1,3-diaryl-diketone and meso-A4-porphyrin ligands, as well as the selection of the lanthanide (III) ion. Furthermore, by varying the denticity of the ancillary ligand and coordination geometry, it is possible to access novel molecular architectures with potential optical, luminescent, and magnetic properties. In addition, the capacity of these compounds to be deposited and systematically arranged on surfaces underscores their significant potential as active components in advanced optoelectronic devices.
Description
Tesis presentada para optar al grado académico de Doctor en Ciencias con mención en Química
Keywords
Rotores, Tierras raras, Óptica no lineal