Interlocking viologen-based lanthanide complexes for multifunctionality: Photochromism, electrochromism, photoluminescence, photomagnetism, and inkless printing and UV shielding applications.

The construction of molecular crystal materials with physical properties that can be dynamically controllable through various stimuli such as light and electricity is of extraordinary significance, while this remains a tremendous challenge. In this context, we demonstrate two novel 2-D multi-function viologen complexes, {[Ln(bcbp)(BDC)(CH 3 OH)(H 2 O) 2 ]·Cl·CH 3 OH·H 2 O} n (1-Eu , and 2-Dy ; H 2 bcbp·2Cl = 1,1′-bis(4-carboxyphenyl)-(4,4′-bipyridinium) dichloride; BDC = p -phthalic acid, and Ln = Eu, Dy). Due to the strong π-π interaction between viologen and BDC in the interlocked structure, both compounds exhibit rapid and reversible responses under the stimuli of UV light and electricity. Furthermore, accompanying the photochromic process, photo-modulated luminescent and photomagnetic behavior have been observed. Considering the excellent photochromic performance, the function filter paper and smart organic glass were successfully prepared and used for ink-free printing and UV light filtering. [Display omitted] • Two interlocking viologen-based lanthanide frameworks with strong π-π interactions were designed and synthesized. • The obtained compounds exhibited fast and reversible chromic under the stimuli of UV light and electricity. • Accompanied by the photochromic process, controllable photoluminescent and photomagnetic behavior have been observed. • The function filter paper and smart organic glass were successfully fabricated and their applications were explored. [ABSTRACT FROM AUTHOR]