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Transformación estructural dependiente de la quiralidad en perovskitas quirales 2D bajo alta presión

Meng-En Sun¹, Yonggang Wang², Fei Wang³

¹Henan Key Laboratory of Crystalline Molecular Functional Materials, Henan International Joint Laboratory of Tumor Theranostical Cluster Materials, Green Catalysis Center, and College of Chemistry, Zhengzhou University, Zhengzhou 450001, P. R. China.

Journal of the American Chemical Society

|April 14, 2023

Resumen

Las perovskitas quirales exhiben cambios estructurales inducidos por la presión y compresibilidad lineal negativa (NLC) debido a enlaces de hidrógeno asimétricos. Las perovskitas achirales carecen de estos efectos dependientes de la quiralidad bajo presión.

Área de la Ciencia:

Ciencias de los materiales
Química del estado sólido
La cristalografía

Sus antecedentes:

Las perovskitas quirales son prometedoras para la optoelectrónica basada en la espintrónica y la polarización.
El mecanismo de transferencia de quiralidad y su impacto en condiciones extremas siguen sin estar claros.
Los estudios sistemáticos que comparan las perovskitas quirales y aquirales bajo presión son escasos.

Objetivo del estudio:

Sintetizar e investigar las perovskitas quirales y aquirales enantioméricas.
Explorar las diferencias estructurales y ópticas dependientes de la presión entre las perovskitas quirales y aquirales.
Para aclarar el papel de la quiralidad estructural en el comportamiento del material bajo presión hidrostática.

Principales métodos:

Síntesis de las perovskitas enantioméricas (S/R-3PYEA) PbI4 y aquirales (rac-3PYEA) PbI4.
Caracterización estructural de alta presión utilizando técnicas como la difracción de rayos X.
Cálculos basados en los primeros principios para analizar la evolución estructural y los enlaces.

Principales resultados:

Chiral (S/R-3PYEA) PbI4 muestra una transición de fase inducida por presión alrededor de 7,0 GPa con un salto rojo de banda y piezocromismo.
Se observa una compresibilidad lineal negativa (NLC) en las perovskitas quirales tras una mayor compresión.
Achiral (rac-3PYEA) PbI4 carece de estas transiciones dependientes de la quiralidad y NLC debido al enlace de hidrógeno equilibrado.

Conclusiones:

La inclinación impulsada por la presión de cationes orgánicos quirales induce enlaces de hidrógeno asimétricos, impulsando transiciones estructurales y NLC en perovskitas quirales.
La asimetría aumentada en las perovskitas quirales conduce a distorsiones significativas de los octaedros [PbI6]4-.
Las perovskitas aquirales no exhiben estos fenómenos debido a las fuerzas contrarrestantes de los enlaces de hidrógeno equilibrados.

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