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Comportamiento magnético dependiente de los sustituyentes de los benzo[e][1,2,4]triazinilos
Marcin Jasiński1, Jacek Szczytko2, Damian Pociecha3
1Faculty of Chemistry, University of Łódź , Tamka 12, 91-403 Łódź, Poland.
Journal of the American Chemical Society
|July 21, 2016
Resumen
Los nuevos mesógenos discóticos con un núcleo benzo[e][1,2,4]triazinyl muestran propiedades térmicas y magnéticas únicas. Estos materiales exhiben el transporte por agujero fotoinducido, destacando su potencial en aplicaciones electrónicas avanzadas.
Área de la Ciencia:
- Ciencias de los materiales
- Química orgánica
- Física de la materia condensada
Sus antecedentes:
- Los cristales líquidos discóticos son conocidos por su autoensamblaje en estructuras columnares.
- Los radicales benzo[e][1,2,4]triazinyl ofrecen un núcleo único para el diseño de mesógenos funcionales.
- La adaptación de sustituyentes en núcleos mesogénicos puede influir significativamente en su comportamiento de fase y propiedades electrónicas.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos mesógenos discóticos basados en el radical benzo[e][1,2,4]triazinyl.
- Investigar la influencia de los sustituyentes N sobre la fase columnar hexagonal (Colh), la expansión térmica y las interacciones magnéticas.
- Evaluar las propiedades de transporte de carga fotoinducidas de estos mesógenos en la fase Colh.
Principales métodos:
- Síntesis de mesógenos discóticos basados en benzo[e][1,2,4]triazinyl con diferentes sustituyentes N.
- Calorimetría de barrido diferencial (DSC) y microscopía óptica polarizada (POM) para estudiar las transiciones de fase y la expansión térmica.
- Mediciones de la susceptibilidad magnética para sondear las interacciones magnéticas.
- Mediciones del transporte por agujero inducido por la luz utilizando el tiempo de vuelo (TOF) o técnicas similares.
Principales resultados:
- Los mesógenos discóticos exhiben una fase Colh por debajo de 80 °C.
- Los derivados de N(1)-fenilo (1a) y 1-PhF-m (1b) muestran una expansión térmica positiva y interacciones antiferromagnéticas.
- Los derivados 1c (X=O) y 1d (X=S) muestran una expansión térmica negativa.
- Interacciones ferromagnéticas débiles observadas en 1c (J/kB = +4,76 K).
- Los compuestos 1a y 1c demuestran el transporte por agujero fotoinducido (μ ≈ 1.3 × 10(-3) cm(2) V(-1) s(-1)) en la fase Colh.
Conclusiones:
- El sustituyente N(1) controla críticamente la organización molecular, la expansión térmica y el comportamiento magnético en los mesógenos benzo[e][1,2,4]triazinyl discóticos.
- Se observa una expansión térmica negativa en los derivados con cadenas laterales alcóxicas/tioalcóxicas voluminosas.
- La presencia de transporte por agujero fotoinducido en la fase Colh sugiere aplicaciones potenciales en electrónica orgánica.
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